Layered MgxV2O5·nH2O as Cathode Material for High-Performance Aqueous Zinc Ion Batteries
King Abdullah University of Science and Technology, Saudi Arabia
The performance of chemically intercalated V2O5 was found to strongly depend on the interlayer spacing, which is related to the radius of hydrated metal ion, which can be readily tuned by using different intercalated metals. We report a layered Mg2+-intercalated V2O5 as the cathode material for aqueous ZIBs. The large radius of hydrated Mg2+ (∼4.3 Å, compared with 3.8 Å of commonly used Li+) results in an interlayer spacing as large as 13.4 Å (against 11.07 Å for Li+-intercalated V2O5), which allows efficient Zn2+ (de)insertion. As a result, the obtained porous Mg0.34V2O5·0.84H2O cathodes work in a wide potential window of 0.1 to 1.8 V versus Zn2+/Zn, and can deliver high capacities of 353 and 264 mA h g–1 at current densities of 100 and 1000 mA g–1, respectively, along with long-term durability. Furthermore, the reversible Zn2+ (de)intercalation reaction mechanism is confirmed by multiple characterizations methods.
The Effect of Polymeric Binders in the Sulfur Cathode on the Cycling Performance for Lithium-Sulfur Batteries
Korea Automotive Technology Institute, South Korea
Recently, great advance of the Li-S battery technology enables its penetration to the power source of the mid- and large-sized devices, which require high energy and power density that cannot be achieved in the Li-ion battery. While the most successful sulfur cathode could be designed by the optimization of the composite structure with carbonaceous materials, the binder system has been recently considered another important factor because the electrode structure of the sulfur cathode suffers huge structural change during the repeated electrochemical cycles. We studied the structural and electrochemical performance of the sulfur cathodes prepared by two different binders, the water-soluble SBR/CMC mixture binder and the traditional PVdF binder. The enhanced battery performance was observed in the SBR/CMC-based electrode and its origin was investigated by post mortem analysis about the electrodes, which confirmed the better mechanical integrity in the electrode compared with the PVdF-based electrode.
Scalable Synthesis of Si-SiOx-C Composite Anode Materials by High-Energy Mechanical Milling and Oxidation Process for Li-Ion Rechargeable Batteries
Kongju National University, South Korea
Silicon has attracted a great deal of attention as the most promising anode for the advanced lithium-ion rechargeable batteries (LIBs) due to the high theoretical capacity of 3579 mAh/g. However, the Si electrode undergoes considerable volume expansion of about ~300% during lithiation/delithiation, which is leading to rapid and severe capacity loss. In this work, we present a scalable synthesis for preparing the cost-effective Si-SiOx-C composite anode material composed of SiOx and carbon matrix phases via high-energy mechanical milling (HEMM) and oxidation process. The formation of the SiOx layer and the carbon phase can act as a buffer layer to mitigate the volume expansion changes during the lithiation/delithiation. The Crystallinity of the milled nanocomposite powders was investigated by the X-ray diffraction technique. Field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HRTEM) were utilized to study the structure and microstructure of the nanocomposite powders. The effect of milling time on changes in crystallite size, and distribution of the nanocomposite powders, and their electrochemical properties were investigated. And the Electrochemical Impedance Spectroscopy (EIS) was used to characterize the anode electrodes on cycling. The results revealed that the nanocomposite delivered a higher charge capacity, prolonged cycle performance along with high coulombic efficiency, due to the enhancement of the electrical conductivity by the carbon layer and the SiOx buffer phase. Consequently, in this work, we report a scalable and cost-effective method for preparing Si-SiOx-C composite anode provides the promising application potentials in the lithium-ion rechargeable batteries.
First-Principles Study of Thiophosphate and Thioantimonate Na-Ion Conductors
National University of Singapore, Singapore
In the search for sodium analogues of the record Li-ion conducting Li10GeP2S12 (SG: P42/nmc), recently a new class of quaternary sodium-ion conductors Na9+xSnxP3−xS12 have been found by various groups. The phases crystallize in a unique structure type (SG: I41/acd) that is characterized by multiple three-dimensionally interconnected pathways for the mobile Na+ ion that contain a large number of intrinsic Na-vacancies. Among them the highest Na+ ion conductivity has been reported for Na11Sn2PS12 (3.7 mS/cm) in spite of a moderate activation barrier. The isostructural Na9+xSnxSb3−xS12 was also reported as possessing excellent air stability. As softening the lattice by a transition from S to Se should diminish the activation barrier for ion migration, the Se analogue has also been synthesized as slightly off-stoichiometric Na11.1Sn2.1P0.9Se12  and its suitability for use in solid state Na-Se batteries was demonstrated by our group.
Here, we employ density functional theory to comprehensively study the stability and homogeneity range of these Na+ conductors: For Na9+xSnxP3−xS12 we explored the range 1.75≤x≤2.25, x=0 (Na3PS4), x=1 (Li10GeP2S12 in LGPS structure type), x=3 (Na4SnS4). Compositions from Na10.875Sn1.875P2.125S12 to Na11Sn2PS12 are thermodynamically stable and the lowest energy configurations at x=1.75 and x=2.25 might also be accessible due to their minute instability (ca. 0.7 meV/atom above convex hull). Stoichiometry variability and the hundreds of identified local minima explain why samples prepared by different groups exhibit slightly different activation energies. The density of states (DOS) was calculated to obtain the band gap of the materials. We further explored the substitution of P by Sb and S by Se. In both cases the formation energies from the ternary sulfides are negative confirming the stability of the quaternary I41/acd phase.
 M. Duchardt et al.; Angew. Chem. Int.Ed. 57 (2018) 1351−1355.
 M. Duchardt et al.; Chem. Mater. 30 (2018) 4134−4139.
Mesoporous Solid Electrolytes for All-Solid-State Batteries by Spark Plasma Sintering
National University of Singapore, Singapore
One of the critical challenges in the development of all solid-state batteries is the high charge transfer impedance at the solid-solid interface between electrolyte and electrode, which severely restricts the power density and energy density at a given cycling rate. The quality of solid-solid interfaces is strongly affected by the sintering technique. The common sintering technique such as cold and hot pressing have certain limitations for industrial uptake as they are time-consuming and hardly scalable. Spark plasma sintering (SPS) is emerging as promising sintering technique for the ultrarapid preparation of dense electrolyte pellets. It utilizes a pulsed direct electrical current to generate heat while pressing. Heating rates as high as 300 K/min can be achieved, and correspondingly fast cooling can be reached by a suitable cooling system. Close to theoretical density is reachable with orders of magnitude shorter holding time. All these merits make spark plasma sintering technique promising to enhance the solid-solid interfaces and improving the performance of all solid-state battery.
Here we demonstrate the use of SPS to both prepare dense membranes and structured membranes with a dense core and porous outer regions that are suitable for the infiltration of active battery materials to prepare all-solid-state batteries with close contact between composite electrode and electrolyte components. Commercial Li1.5Al0.5Ge1.5(PO4)3 (LAGP) as well as LAGP prepared by melt-quenching is converted by spark plasma sintering for just 5 min at 700 ºC into either dense solid electrolyte pellets or – via the inclusion of sacrificial pore formers – into membranes that contain a dense central region and an outer region that can take up active material to form a monolithic all-solid state battery.
All-Solid-State Sodium-ion Batteries Realized by Solution Processable Thioantimonate Solid Electrolyte
National University of Singapore, Singapore
The high cost of electrode materials and stringent heat dissipation requirement of flammable liquid organic electrolytes impede a wider application of current lithium-ion batteries especially in large scale energy storage systems. All-solid-state sodium-ion batteries have become promising alternative with a strong potential to overcome these bottlenecks. The higher abundance and more even geographical distribution of sodium-based raw materials along with the possibility to eliminate costly copper as current collector allow for a significant cost reduction. The intrinsically non-flammable ceramic sodium electrolytes, also reduce the need for heat dissipation and enable a much wider working temperature range.
Among the solid electrolytes studied so far, sulfides have attracted much research interest due to their high ionic conductivity and capability of being directly cold pressed onto electrodes. However, most of these (including the widely studied thiophosphates) are vulnerable to environmental moisture and oxygen, leading to irreversible side reactions. Recently, a group of dry-air-stable thioantimonate electrolytes were proposed. Due to the stronger binding of soft Sb to soft sulfur than to comparatively hard oxygen, these electrolytes maintain Sb-S binding in contact with oxygen and various polar solvents including water, thus making some of them solution-processable.
Solution-processable solid electrolytes greatly facilitate the fabrication of high performance composite electrodes as well as electrode:electrolyte interfaces, as the electrolyte can be conformally coated onto small particles of active battery materials or infiltrated into porous frameworks ensuring close electrode:electrolyte contact and thereby a smooth charge transfer across the interfaces.
In this work, the solution processable solid electrolytes Na3SbS4 and Na11Sn2SbS12 were synthesized and characterized. Various dopants and their compatibility with common solvents were explored. Eventually, by identifying a favorable electrode-electrolyte-solvent combination, all solid state sodium batteries have been assembled. The configuration and fabrication was also optimized to reach a high rate capability and relatively stable cyclability.
Free-Standing Vertically Aligned Carbon Nanotubes-Graphene Foam Composite Electrode for High Power Rechargeable Zn-Air Battery
1Nanyang Technological University, Singapore; 2Nanjing Tech University, China
We report a VACNT-GF composite with Fe and Co-based single atom catalytical active centers as free-standing electrodes for ZABs. The NPFeCo-VACNT-GF samples consists of single atom Fe and Co sites anchored on the outer walls of N and P doped CNTs, and electrochemical measurements show that the N and P co-doping and co-existence of Fe and Co atoms are crucial to the good performance of NPFeCo-VACNT-GF samples. The NPFeCo900-VACNT-GF shows significantly higher peak power density and stability than commercial materials in assembled Zn-air cells due to its high conductivity, high surface area and favorable mass transfer properties, being able to stably operate for over 200 hours.
Origin of Extra Capacity in Advanced Li–Rich Cathode Materials for Rechargeable Li−Ion Batteries
AGH University of Science and Technology, Poland
Among the cathode materials, lithium layered oxides provides high energy density solution. Additionally, lithium manganese oxides are intensively explored due to the Mn abundance, low toxicity and safety. Recently, manganese-based Li-rich oxides are recognized as promising candidates for lithium ion batteries. Li2MnO3 combined with LiMnO2 oxides creates new group that offers access to much higher energy densities than commercial layered oxide electrodes . However, mixed metal oxides exhibit voltage and capacity loss during first activation charge-discharge cycle involving irreversible structural unstable and oxygen removal from the cathode which is a significant limitation for commercialization . The capacity decay can be partially reduce by substitution of Mn by another transition metal in LiMnO2 structure. Therefore, current research aims to find the optimal combination of xLi2MnO3·(1-x)LiMO2, also formulated as Li[LiyMn1-y-zMz]O2 (M = transition metal) resulting in significantly increased theoretical capacity (>250 mAh g-1) and structural stability.
In this work, the origin of extra capacity in Li–rich layered cathode materials are investigated by means of structural, transport and electrochemical measurements. xLi2MnO3•(1-x)LiMO2 also recordedas Li[LiyMn1-y-zMz]O2 (M= Mn, Ni) were synthesized via sol-gel process and the results of the structural determination of X-ray diffraction measurements and the refinement by the Rietveld technique are presented. SEM images and EIS measurements were also performed. To analyze the electrochemical properties, the Li/Li+/xLi2MnO3•(1-x)LiMO2 (M= Mn, Ni) charge/discharge tests were used.
This work was supported by the Polish Ministry of Science and Higher Education (MNiSW) on the basis of the decision number 0197/DIA/2016/45.
Work was realized by using the infrastructure of the Laboratory of Conversion and Energy Storage Materials in the Centre of Energy AGH.
 A. Iturrondobeitia et al. , Electrochim. Acta. 247 (2017) 420–425.
 B. Strehle, et al., J. Electrochem. Soc. 164 (2017) A400–A406.
Structural Properties Evaluation of NASICON-Na3Fe2-yMny(PO4)3 as a Cathode Material for Na-ion Batteries
1AGH University of Science and Technology, Poland; 2AGH University of Science and Technology, Poland; 3Institute of Low Temperature and Structural Research, Polish Academy of Science, Poland
Recently it is observed that Na-ion batteries (NiBs) are of great intererest in terms of their potential application as partial replacement for Li-ion technology, escpecially in large-scale energy storage systems. According to the above, the chemical and thermal stable, safe and harmless for environment cathode and anode materials for NiBs are still being searched. Herein, we concentrated mostly on cathode materials for abovemetioned batteries.
Among the polyanionic phosphate-based compounds, the NASICON structures with general formula Na3Fe2-xMnx(PO4)3 seem to be one of the most interesting potential cathode materials for NiBs. Due to strong covalent bonds in PO43- anions, these structures are thermal and chemical stable, which contributes to the safety of usage [1-2].
Na3Fe2(PO4)3 was intensively investigated in ‘80s, mostly in terms of two polymorphic types of structure, which occurrence is strongly depended on temperature (monoclinic phase under 95oC and rhombohedral phase above 145oC). Herein, we report deep analysis of structural properties of Na3Fe2(PO4)3 and Na3Fe2-yMny(PO4)3 (y = 0.1; 0.2, 0.3, 0.4). Based on HT-XRD, DSC and TGA curves, the influence on structure stability of Mn doping in Fe sublattice is provided. Owing the possible application of these compounds in NiBs, the investigation of redox processes (based on Fe/Mn oxidation state) was highly required. For this purpose the XPS and Mössbauer analysis was employed. Additionaly the powders morphology analysis (SEM/BSE images and EDS mapping) was conducted, that allowed to confirm successful Mn substitution in Fe sublattice.
 I. Lyubutin et. al, Solid State Ionics 31 (1988) 197–201.
 C. Masquelier, et. al, Chem. Mater. 12 (2000) 525–532.
This work was supported by the Polish Ministry of Science and Higher Education (MNiSW) based on the decision number 0020/DIA/2016/45. Work was realized by using the infrastructure of the Laboratory of Conversion and Energy Storage Materials in the Centre of Energy AGH.
Polypyrrole Intercalated VOPO4 for Zinc-Ion Batteries
Nanyang Technological University, Singapore
The scarcity of lithium resources and the rising price of lithium-ion batteries call for novel and cost-effective energy storage systems. In this regard, zinc-ion batteries are promising, as unlike lithium, zinc is inexpensive and can render higher battery capacities via two-electron reaction per cation. However, designing a cathode to host Zn2+ cations still remains a challenge. Although few investigations with layered manganese and vanadium based oxides have shown benefits of higher interlayered distance, and crystal water in the structure, many of these materials exhibit a low discharge voltage, thus limiting the energy density.
Inorganic phosphates could serve as suitable hosts for zinc-ions, aiding the development of high voltage aqueous zinc-ion batteries. Among others, Vopo4.2H2O is an attractive candidate due to its layered structure with high interlayer spacing, the presence of crystal water and a high theoretical capacity of 125 mAh/g and a high discharge voltage. Our investigations have revealed good discharge voltage and capacity for Vopo4.2H2O cathode in aqueous zinc-ion battery. However, rapid capacity fading of the cathode was observed, which is attributed to the collapse of the layered Vopo4.2H2O structure. To address this challenge, the Vopo4.2H2O structure was intercalated with polypyrrole, which improved the structural integrity during the charge/discharge cycles. A significant improvement in the capacity retention of the cathode was observed with a slightly reduced capacity. This idea could be extended to investigate other layered cathode materials with large interlayer spacing as hosts for other divalent and even trivalent cations.
 Huang, Jianhang, et al. "Polyaniline-intercalated manganese dioxide nanolayers as a high-performance cathode material for an aqueous zinc-ion battery." Nature communications 9 (2018).
 Kundu, Dipan, et al. "A high-capacity and long-life aqueous rechargeable zinc battery using a metal oxide intercalation cathode." Nature Energy 1.10 (2016): 16119.
Organic-Inorganic Halide with Perovskite Structure as Active Materials for Sulfide-Based All-Solid-State Lithium Secondary Batteries
1Hokkaido University, Japan; 2Universidad de Antioquia, Colombia
In bulk-type all-solid-state lithium secondary batteries with sulfide-based solid electrolytes, large amounts of solid electrolytes have been mixed in the electrodes to enhance lithium-ion diffusion. However, the addition of the solid electrolytes decreases the ratio of the active material in the batteries, resulting in the decrease of the total energy density of the batteries. To solve this issue, we focused on the use of active material with high lithium-ion diffusion. This property can form sufficient lithium-ion path in the electrodes without the addition of the solid electrolytes. Organic-inorganic halide with perovskite structure have been investigated as materials for light emitting diodes, solar cells, and lithium-ion batteries using liquid electrolytes.1,2 The organic-inorganic halide perovskite (OIHP) has the coefficient of Li+ diffusion reaching as high as ~10-7 cm2 s-1.2 This property makes the OIHPs a potential alternative to be used as the electrodes for the all-solid-state batteries without the addition of solid electrolytes. Here, two-dimensional (2D) OIHP with a structure (CH3(CH2)2NH3)2(CH3NH3)2Pb3Br10 was evaluated as an active material for a sulfide-based all-solid-state battery. To enhance the lithium-ion diffusion in the electrode, the battery operating temperature was set to 100 °C. The battery operated at 100 ºC showed a reversible capacity of more than 242 mAh g-1 for 30 cycles even though the electrode did not contain solid electrolyte, keeping a low resistance between electrode/electrolyte interface after 30 cycles. This result suggests that the OIHP has a potential as an active material for a sulfide-based all-solid-state battery.
(1) D. Ramirez, et al., Inorg. Chem. 57, 4181 (2018).
(2) N. Vicente, et al., Adv. Energy Mater. 7, 1700710 (2017).
High Energy All-Solid-State Lithium Battery Material with Homogeneous Interfacial Chemistry
Ulsan National Institute of Science and Technology, South Korea
All-solid-state lithium batteries (ASSLBs) have received great attention for substituting conventional lithium-ion batteries (LIBs). However, several significant challenges, such as the high interfacial resistance, side reactions and poor contact area between active materials and sulfide solid electrolytes (SEs), which gives rise to the decrease of utilization fractions of active material. Furthermore, the structural transformations and decompositions of the cathode and SE create the by-products with low ionic conductivity at the interface.
To resolve such problems in the ASSLBs, many researchers have mainly concentrated on the size and morphological controls of the cathode particle with incorporation of the surface coating layer on the cathode particle. However, surface treatment methods accompanied a multi-step sol-gel process of active materials which can cause the increase of the process time and capital cost. In addition, sol-gel coating method can make the cathode materials aggregated when it is applied into large-scale.
Herein we report a high performance nickel-rich LiNi0.8Co0.1Mn0.01O2 (NCM811) cathode with a coating layer. The prepared cathode demonstrated extremely high electrochemical performance at room temperature with high structural and morphological integrity. When tested in a full-cell with high loading level of ~20 mg cm-2, this cathode outperforms in any nickel-rich cathodes in the ASSLBs. This work suggests that our strategy can simultaneously address the surface stability with the sulfide SEs and practical perspectives by the newly developed surface engineering method.
"MnCo2O4.5 Nanoparticles with Spinel Structure as Bifunctional Catalyst for Rechargeable Zinc-air Batteries"
Kongju National University, South Korea
The quality of progressing in the development of safety and highly efficient energy density
power sources has attracted during decades. Nowadays, Li-ion batteries are used as the most
prominent power source because they have high energy density, long cycle life, and absence of
memory effect. However, lithium ion batteries still do not offer enough energy density for new
applications, such as new portable electronic devices, robot, electric vehicle, and stationary
storage applications, although broad research has been worked out to increase energy storage
capability. In this view, many researchers are intensively studying on metal-air batteries with the
advantages of high energy density, long term use and safety issues. In order to commercialize
metal-air batteries, various issues need to be addressed. In particular, air cathode is a key factor
in determining the capacity and cycle performance of metal-air batteries. The air cathode still
suffers from the slow rate of the oxygen reduction reaction (ORR) and the oxygen generation
reaction (OER), which causes the charge/discharge over-potential and finally makes poor cycle
performance. To reduce over-potentials for both ORR and OER, recently, the mixed valence
transition metal oxides with spinel structures are becoming potential air cathode catalyst
candidates because they behave as bifunctional catalysts.
In this work, we will present MnCo 2 O 4.5 nanoparticles as bifunctional catalyst for air cathode.
The MnCo 2 O 4.5 nanoparticles were synthesized by solvothermal reaction without any surfactant
assistance and examined their electrochemical performance.
Transition Metal Oxide Nanoparticles with Perovskite Structure as Bifunctional Catalyst for Rechargeable Aluminum-air Batteries
Kongju National University, South Korea
Electronic devices have been developing rapidly, which results in increasing demand for high energy/power density sources. There has also been a strong incentive to develop electric vehicles by the introduction of batteries to reduce the dependence on petroleum oil and mitigate the tailpipe emissions. In this point, lithium-ion batteries have dominated the electric vehicles market due to their high capacity and energy efficiency. However, the insufficient energy density of lithium-ion batteries is still a big problem for the development of electric vehicles. In this regards, many researchers have studied rechargeable metal-air battery has been considered as one of the most promising power sources for electric vehicles due to some attractive advantages, such as the high energy density, low cost and environment-friendliness, and open battery configuration that uses air as the reactant. However, one of the most important problems in the practical use of metal-air batteries is the slow rate of oxygen reduction reaction (ORR) and oxygen generation reaction (OER), which causes a large discharge-discharge transient voltage. To reduce over-potentials for both oxygen reduction reaction and oxygen evolution reaction, recently, the mixed valence transition metal oxides are emerging potential candidates for bifunctional catalysts due to their high abundance, ease of preparation and good redox stability in alkaline solutions.
In this study, we will present hydrothermal synthesis without any surfactant assistance to obtain perovskite structure metal oxide nanoparticles. The as-synthesized samples were explored as bifunctional catalyst for rechargeable aluminum-air batteries that exhibits enhanced electrochemical properties.
Separator Design to Effectively Trap Lithium-Polysulfides for High Performance Li–S Batteries
Kongju National University, South Korea
lithium–sulfur (Li–S) battery has attracted as potential next-generation rechargeable batteries since elemental sulfur (S8) as cathode material exhibits a high theoretical capacity of 1672 mAh g-1 and can provide a high theoretical gravimetric energy density of 2600 Wh kg-1. In addition, sulfur has the favorable advantages of being inexpensive due to a common by-product of petroleum refining and an environmentally friendly element. However, the fast capacity fading of Li–S battery has so far hindered their commercial application, e.g., the low intrinsic conductivities of sulfur (5 × 10-30 S cm-1 at 25 °C) and formation of intermediate products (lithium-polysulfides, Li2Sm, 3 ≤ m ≤ 8) result in unstable electrochemical contact at the sulfur cathode, affecting the cycle lifetime and efficiency of Li–S battery. In order to solve these drawback issues, several strategies have been proposed and improve the overall electrochemical performance of the Li–S battery. Among them, the preparation of sulfur–carbon composites by confining sulfur into the carbon framework, allowing intimate contact between the active material and the conductive matrix is the frequently used approach. In addition, the protected lithium anode by using additives or conductive polymers has also shown a favorable advance on the performance of Li–S battery. Particularly, the reconfiguration of Li–S cells has been proposed such as involving insertion of carbon interlayer between the separator and the sulfur cathode to reduce the internal resistance in the cell and capture the soluble lithium-polysulfides intermediate.
In this presentation, we proposed a porous ceramic coated separator to suppress the migration of soluble lithium-polysulfide, and improved the overall electrochemical performance of Li–S batteries.
Li(I)–Purine Based Solid Electrolyte: Role of Equivalents of Li(I) on Conductivity
Indian Institute of Technology Kanpur, India
Solid state lithium ion batteries (LIBs) utilize solid electrolytes which act as promising candidates for the replacement of conventional liquid electrolytes thereby successfully addressing the safety concerns.1 A large number of different types of solid electrolytes such as inorganic, organic and hybrid/composite polymer electrolytes have been productively developed to achieve efficient and high-performance batteries.2 With an increasing demand for biodegradable and environment-friendly alternatives in the fields of energy and electronics, we designed a bioinspired Li(I)-purine crystalline complex. Its crystallographic structure was determined using X-ray and it was screened for its conductive properties. Notably, it displayed a considerably good conductivity of the order of 10-4 S cm-1 at 323 K. Further, the role of equivalents of Li(I) on conductivity was established using a series of experiments by varying the concentrations of Li(I) salt. Such robust and easily synthesized biomaterials can effortlessly be processed and fine-tuned further to enhance their electrical characteristics, thereby leading to increased cell-performance.3
- A. Manthiram, X. Yu and S. Wang, Nat. Rev. Mater., 2017, 2, 1–16.
- L. Fan, S. Wei, S. Li, Q. Li and Y. Lu, Adv. Energy Mater., 2018, 8, 1–31.
- L. Wang, D. Chen, K. Jiang and G. Shen, Chem. Soc. Rev., 2017, 46, 6764–6815.
LiSc0.06Mn1.94O4 as Prospective Cathode for Lithium Ion Batteries for Mobility Application
International Advanced Research Centre for Powder Metallurgy and New Materials, India
LiMn2O4 is a promising cathode material for lithium-ion batteries due to good structural stability at high rate charge/discharge process. However, it suffers from capacity fade due to Mn-dissolution and Jahn-Teller distortion. In order to overcome these problems, numerous efforts have been focused on doping/coating on the spinel structure by metal ions/oxides. Herein, we report the synthesis of Sc-doped LiScxMn2-xO4 (x=0.0-0.1) spinel by solid-state method. The XRD data confirmed the formation of single-phase (Fd-3m) spinel structure. The lattice parameter ‘a’ decreases upon Sc-doping is due to the change in the interatomic distance of the metal oxide bonds (increased Li-O and decreased Mn-O bond-length by ~0.01Å). SEM images of the doped spinels revealed that rod like morphology with a narrow aspect ratio of 1-1.5. The appearance of Sc2p3/2 and Sc2p1/2 peaks at 402.5 and 407.2 eV (compared to 401.71 and 406.46 eV for Sc2O3) in XPS spectrum confirms the presence of scandium ion in the crystal lattice. The symmetric stretching of Mn(Sc-O) in LiSc0.06Mn1.94O4 shifts lower value than Mn-O in LiMn2O4 indicating the occupancy of Sc3+ ion in the octahedral site. The obtained diffusion coefficient value (from GITT titration) of LiSc0.06Mn1.94O4 is one-order of magnitude higher than that of undoped LiMn2O4. Whereas, the charge transfer resistance value of the doped spinel five times lower than the pristine compound. LiMn2O4 delivers a discharge capacity of 117mAhg-1 with a capacity retention of 74% and LiSc0.06Mn1.94O4 delivers 114mAhg-1 with a capacity retention of >90% at 1C after 500 cycles. LiSc0.06Mn1.94O4 exhibits excellent rate capability which is due to enhanced Li ion diffusion kinetics and reduced charge transfer resistance. The structure and morphology of Sc-doped electrode after 500 cycles remains undamaged without any cracks and Mn-rich agglomeration. These results suggest that LiSc0.06Mn1.94O4 can be a potential cathode material for lithium ion batteries for mobility applications.
Mechanochemical Synthesis and Characterization of Li4GeO4-Li2WO4 Glass-Ceramic Electrolytes
Osaka Prefecture University, Japan
Oxide-type all-solid-state batteries have attracted significant attention owing to their safety. For the construction of the electrode/electrolyte interface with favorable charge transfer, it is required to develop oxide electrolytes with high conductivity and ductility. We have reported that the addition of Li2SO4 is effective in improving the ductility of oxide glass . Further improvement in ductility is expected by the incorporation of Li2WO4 because it has a lower melting point than Li2SO4. Moreover, highly ion-conducting metastable crystals which cannot be obtained by the conventional solid state reactions are often precipitated by crystallization of mother glasses. The Li4GeO4-based crystals with LISICON structure were reported to show the conductivity of approximately 10-5 S cm-1 at 25°C .
In this study, glass-ceramic electrolytes of xLi4GeO4·(100-x)Li2WO4 (x = 25, 50, 60, 70, 80, 90 mol%) were prepared by mechanochemical treatment and subsequent heat treatment, and their ductility and conductivity were evaluated.
X-ray diffraction patterns revealed that obtained samples at x = 70-90 mol% were amorphous after mechanochemical treatment. Relative densities for green compacts prepared by cold pressing the prepared samples at 720 MPa were 78-79%. A metastable phase similar to hexagonal Li4SnS4  was precipitated by heating the glasses (x = 70-90 mol%) at 250°C. Cations in the samples randomly occupy the tetrahedral sites in the structure with hexagonal close-packed oxygen lattice. By heating at 700°C, the cations became ordered and the LISICON-phase was formed. The 90Li4GeO4·10Li2WO4 (mol%) with the LISICON structure showed the high conductivity of 3.0×10-5 S cm-1 at 25°C.
 M. Tatsumisago et al., J. Power Sources, 270 (2014) 603-607.
 E.I. Burmakin et al., Russian J. Electrochem., 30 (2003) 1124-1129.
 K. Kanazawa et al., Inorg. Chem., 57 (2018) 9925-9930.
Characterization of Na3Zr2Si2PO12-Na3SbS4 Composite Electrolytes with Sodium Ion Conductivity
Osaka Prefecture University, Japan
All-solid-state sodium batteries are expected as one of next generation batteries with high safety, high energy density and low material cost. Formation of close interfacial contacts between electrode active materials and solid electrolytes is a critical issue for developing bulk-type all-solid-state sodium batteries with high capacity. Na3Zr2Si2PO12 (NASICON) is a promising solid electrolyte material with high Na+ ion conductivity and atmospheric stability. The dense NASICON ceramics show high room temperature conductivities of about 10-3 S cm-1. However, NASICON solid electrolytes for the battery application are prepared by high sintering temperature at above 1000oC. Undesirable side reactions with electrode active materials occur at high temperatures when batteries are fabricated using a co-sintering process to form close solid-solid interfaces.
Recently, we reported NASICON-based composite electrolytes combined with the Na3PS4 sulfide electrolyte having interfacial formation ability. The pelletized composite with 70 wt% NASICON, which prepared by cold-pressing without high-temperature sintering, exhibited the conductivity of 1.1×10-3 S cm-1 at 100oC.
In this study, we focus on Na3SbS4 witha higher conductivity than Na3PS4 as an alternative sulfide component, which will contribute to increasing conductivity and decreasing the sulfide for oxide-based electrolytes. The composite electrolyte powders in the system Na3Zr2Si2PO12-Na3SbS4 were prepared by ball-mill mixing with NASICON and Na3SbS4. The composite powders at the NASICON rich compositions (70-80 vol%) were prepared and pelletized by uniaxially cold-pressing, followed by heat-treatment to enhance their crystallinity. The composite green compact (unfired molded bodies) with 70 vol% NASICON exhibited high total conductivity of 2.1×10-3 S cm-1 at 100oCand low activation energy of 24.5 kJ mol-1. Cross-sectional SEM-EDX analyses of composite reveled that NASICON core particles were coated with Na3SbS4. The use of Na3SbS4 is thus favorable to increase the conductivity of oxide-based composite electrolytes.
A Mechanistic Insight into Na2FePO4F as a Cathode Material for Secondary Batteries
1Indian Institute of Science, India; 2ICMPE, UMR 7182, CNRS, Universite-Paris East, France
Na-ion batteries have emerged as an economical and viable alternative to Li-ion batteries owing to their high abundance, low cost and operational similarity. Due to versatile nature in terms of anion substitution coupled with high thermal and structural stability, polyanionic materials are now extensively studied as cathode materials for secondary batteries. Major advantage in using polyanions as cathode is the enhanced voltage due to high electronegativity of the central metal atom. Fluorine being the most electronegative element in the periodic table can be combined with other anions resulting in further increase of the cell voltage. Na2Fe(II)PO4F is one such example where F-ion is combined with PO4-group making it a 3-V cathode material. The present work involves an economic solution-combustion synthesis starting from Fe(III) precursor yielding phase-pure carbon-coated material in one-minute. The material was studied as cathode for both Li-ion and Na-ion batteries. Different (dis)charge profiles were observed in both configuration. While the operating mechanism of the material in Li-configuration has been well explained by some groups, the redox mechanism of (de)intercalation is still under debate for Na-configuration. An effort was made to study the mechanism by the help of in-operando XRD combined with some theory calculations. The structural, electrochemical and mechanistic analysis will be presented in detail.
Polymer Coating Effect on Deposition and Dissolution Reactions of Lithium Metal Anode
Mie University, Japan
Electric vehicles are considered to play a important role in reducing fossil fuel consumption and carbon dioxide emissions. Vehicles driving range per one charge is largely determined by the limitation of electric energy stored in batteries. In this regard, there is a strong demand for developing a new battery system with higher energy density than conventional lithium ion battery. Lithium-air secondary batteries are attracting attention as next generation secondary batteries capable of achieving high energy density. However, the lithium metal anode in the battery has a problem in low cycle performance due to its dendritic growth and side reactions with impurities. In this study, the polymer is directly coated on the lithium anode surface, and the effect of coating on electrodeposition/dissolution reaction of lithium metal anode in organic electrolyte solution cell are investigated.
Crosslinked polymer composed of poly (ethylene glycol) diacrylate (PEGDA) and poly (ethylene glycol) methyl ether acrylate (PEGMA) with various molecular ratios were used as the coating layer. For fabrication of the test electrode, a mixture of appropriate amount of PEGDA and PEGMAsolution was directly applied to lithium metal sheet and then irradiated with ultraviolet light to obtain a polymer-coated lithium electrode. Electrochemical lithium electrodeposition/dissolution reactions were examined using two electrode test cell assembled with copper as cathode, polymer coated lithium anode, and 1 mol dm-3LiN(SO2F)2in 1,2-dimethoxyethane as electrolyte.
The charge-discharge measurements confirmed the better cyclability of electrodeposition/dissolution reactions for the crosslinked PEGDA-PEGMA coated lithium anode than the uncoated, 100%-PEGDA and 100%-PEGMA coated ones. Lithium electrodeposition/dissolution performance of the polymer coated lithium anode will be discussed based on the electrochemical and surface structural characterizations.
This work was financially supported by the Advanced Low Carbon Technology Research and Development Program of the Japan Science and Technology Agency for Specially Promoted Research for Innovative Next Generation Batteries (JSTALCA SPRING).
Layered Na2Mn3O7 as a Versatile Cathode Material
Indian Institute of Science, India
Battery world, particularly the portable battery market, is mostly dominated by the Li-Co mixture based cathodes like LiCoO2. The resource constraints of Li and Co has increasing paved away for alternate chemistry. In this senario, manganese-based layered materials are promising owing to their low-cost, resource-friendly, non-toxic nature with high operational safety. Already some of the Li-Mn based systems like LiMn2O4 (LMO) and LiNi1/3Mn1/3Co1/3O2 (NMC) have been commercialized. Inspired by this potential advantages and polymorphism associated with Mn-based systems, here, ternary layered Na-Mn-O based metal oxide (Na2Mn3O7) was synthesized using different synthetic routes to tune the size and morphology of Na2Mn3O7 particles. The phase pure Na2Mn3O7 crystallizes in triclinic layered structure (s.g. P-1). It consists of Mn in +IV oxidation state with electrochemically active Mn4+/Mn3+ redox center. The as-synthesized black powder worked as a versatile cathode for the Li-ion, Na-ion, K-ion and Zn-ion batteries. The systematic electrochemical studies were carried in both the aqueous and non-aqueous electrolytes. It delivered a reversible capacity of ~160, ~140, ~134 and ~330 mA h g-1 respectively with Li, Na, K and Zn metal as anode in half-cell architectures. Interestingly, Li-ion battery exhibited solid-solution type (de)intercalation upon the variation of Li-ion (A) concentration in Na2AxMn3O7, whereas Na-ion, K-ion and Zn-ion (de)intercalation involve two-phase redox reaction. The detailed (de)intercalation mechanism along with diffusional studies of the various alkali-ions (Li/Na/K) along with Zn-ion will be described to present Na2Mn3O7 as a versatile cathode material.
Novel Titanium Based Anodes for Rechargeable Batteries
Indian Institute of Science, India
SONY in 1990s introduced rechargeable lithium-ion batteries (LiBs) as reliable power source for portable electronics. While cathodes are extensively improved, graphite anode (0.2V, 372 mAh/g) used in LiBs is unsafe. Following work on high rate safe Li4Ti5O12 (LTO) anode, titanium based anodes with Ti(IV)/Ti(III) redox is targeted. Orthorhombic Cmca MLi2Ti6O14 (M = Sr, Ba, Pb) LiB anodes prepared rapidly (1 min – 2 hours) at low temperatures (800 - 900 oC) showed electrochemical performance (1.3-1.45 V, 100-160 mAh/g) comparable to LTO [1-3]. Further, lithium (de)insertion (0.58V, 70 mAh/g) was observed for first time in Narsarsukite Na2TiOSi4O10 (tetragonal, I4/m) having empty tunnels of SiO4 tetrahedra .
Research efforts on sodium ion batteries (SiBs) debuted much before LiBs following research diversions in energy post 1973’s oil crisis. Overwhelming use of LiBs to satisfy wireless revolution steered away focus from SiBs. However, SiBs are more suitable for MWh stationary grid energy storage with lower costs due to sodium abundancy and preventing use of expensive copper current collector. With graphite inoperative in SiBs (large Na+ size), hard carbon and Na2Ti3O7 are promising low voltage anodes for SiBs.
We explored PbTi3O7 (monoclinic, P21/m) a polymorph of (Ti3O7)2- anion. Reversible Na+/Li+ storage (~300/~400 mAh/g) occurs in a complex conversion-alloying-intercalation mechanism triggerring Pb(IV)/Pb(II)/Pb(0) redox in addition to Ti(IV)/Ti(III) redox like PX-PbTiO3. With similar sodium/lithium (de)insertion in monoclinic C2/m Freudenbergite Na2A2Ti6O16 (A = Fe/Al), an overview of titanate based anodes for rechargeable batteries will be summarised.
 A. Dayamani, G. Shinde, A. Chaupatnaik, et al, J. Power Sources, 2018, 385: 122-129.
 A. Chaupatnaik, P. Barpanda, J. Mater. Res., 2019, 34: 158-168, .
 A. Chaupatnaik, P. Barpanda, J. Electrochem. Soc., 2019, 166: A5122-A5130.
 A. Chaupatnaik, M. Srinivasan, P. Barpanda, ACS Appl. Energy Mater. (Provisionally accepted).
 A. Chaupatnaik, A. Rambabu, P. Barpanda, ECS Meeting Abstract, 2018, MA2018-02, 286.
Phase Stability Analysis of the NASICON-Na3Fe2-yMny(PO4)3 Cathode Material for Na-ion Batteries
AGH University of Science And Technology, Poland
Polyanionic phosphate-based compounds are widely recognised as suitable electrode materials for modern battery technologies, namely Li-ion (LiBs) and Na-ion (NiBs). They usually exhibit significant chemical and structural stability that is crucial for safety of usage and allows for maintaining desired properties along the batteries lifetime. Within this group NASICON-Na3Fe2-yMny(PO4)3 compounds are noticeable candidates for cathode materials for NiBs. They are formed of environmentally friendly and relatively inexpensive elements what allows for application in large-scale energy storage systems that will serve important role in future energy networks based on renewable energy sources.
It was documented in ‘80s  that NASICON-Na3Fe2(PO4)3 undergoes two phase transitions: from monoclinic α phase to intermediate β under 95oC and then to rhombohedral γ phase above 145oC. To our best knowledge, up to now there was no data considering presence of the phase transitions in manganese containing compounds. In this work we focus on the analysis of the structural stability of the Na3Fe2-yMny(PO4)3 materials with composition x=0, 0.1, 0.2, 0.3 and 0.4.
The analysis of the phase transitions in the studied group of materials was performed with use of the HT-XRD technique. We provide comprehensive analysis of characteristic reflection evolution as well as detailed insight of geometric changes of the materials unit cell. We show that manganese content stabilises the higher symmetry rombohedral phase that is known of improving ion diffusion in NASICON type structures.
This work was supported by the Polish Ministry of Science and Higher Education (MNiSW) on the basis of the decision number 0020/DIA/2016/45. Work was realized by using the infrastructure of the Laboratory of Conversion and Energy Storage Materials in the Centre of Energy AGH.
 I.S. Lyubutin, O.K. Melnikov, S.E. Sigaryov, V.G. Terziev, Solid State Ionics 31 (1988) 197–201.
Ionic Conductivity and Chemical Stability of Li7P3S11 Thionitride Electrolytes Prepared via a Mechanochemical Process
Osaka Prefecture University, Japan
In conventional lithium-ion batteries, organic liquid electrolytes are used between positive and negative electrodes. For next generation batteries, all-solid-state batteries using solid electrolytes without leakage and flammability are attracting. The solid electrolytes are needed to have a high ionic conductivity, good formability, and chemical stability. Although sulfide solid electrolytes show the high conductivity (> 10-4 S cm-1) without high temperature sintering, they tend to react with moisture in air and generate H2S gas.
Improving the chemical stability of sulfide electrolytes to H2O molecules is a major problem to be overcome in the application to all-solid-state batteries. We reported the glass at the composition of 75Li2S·25P2S5 (mol%) is the most stable in air in the Li2S-P2S5 binary system . For further reducing the amounts of H2S gas generated from sulfides, anion-substitution in sulfides is useful. By replacing a part of sulfide ions with oxide ions in the 75Li2S·25P2S5 glass, the amount of H2S decreased, but the ionic conductivity decreased . On the other hand, a partial use of Li3N instead of Li2S in the 75Li2S·25P2S5 glass and glass-ceramic suppressed H2S generation with maintaining high ionic conductivity .
In this study, we focused on the nitrogen doping to the glass-ceramic at the composition 70Li2S·30P2S5 (Li7P3S11), which has the highest ionic conductivity in the binary system. The thionitride (70-1.5x)Li2S·30P2S5·xLi3N glass-based electrolytes were prepared by a mechanochemical process. The effects of the Li3N substitution to structure and ionic conductivity of the electrolytes were investigated. The glass-ceramic with x = 5 showed the highest conductivity of 3.2×10-3 S cm-1 at 25°C. The addition of Li3N suppressed the H2S generation from Li7P3S11 exposed to air.
 H. Muramatsu et al., Solid State Ionics, 182 (2011) 116.
 T. Ohtomo et al., J. Solid State Electrochem., 17 (2013) 2551.
 A. Fukushima et al., Solid State Ionics, 304 (2017) 85.
Surface Modification of LiMO2 for All-Solid-State Lithium-ion Batteries Using Sulfide Solid Electrolytes
1Hanyang University, South Korea; 2Seoul National University, South Korea
Li+ conductivities of the state-of-the-art sulfide solid electroytes have reached ~10-2 S cm-1 at room temperature, which is comparable to that of organic liquid electrlyte. Moreover, softness of sulfide materials allows for mechanical sintering, which could minimize undesirable chemical reaction with electroacitve materials during fabrication of all-solid-state batteries. The application of layered oxide cathode materials used in conventional lithium-ion batteries is the key to achieving high energy density of practical all-solid-state lithium or lithium-ion batteries (ASLBs). However, serious side reactions at interfaces between oxide cathode materials and sulfide solid electrolytes result in poor rate capabilities of ASLBs. In this regard, interfacial engineering is required. Unfortunately, interfacial phenomena in ASLBs has not been well understood. Moreover, only a few materials have been investigated to enhance the interfacial stability. Herein, our results on Li3BO3-based coatings on LiCoO2 for ASLBs are presented. The Li3BO3-based surface modification shows improvement in power density and cyclablity. The underlying enhancement mechanism will be also discussed.
Promising Electrochemical Properties of Sugarcane Bagasse Derived Hard Carbon for Sodium-ion Batteries
1National Chiao Tung University, Taiwan; 2National Central University, Taiwan; 3National Cheng Kung University, Taiwan
In realizing the future aspects of sodium-ion batteries, a resource-abundant and cost-effective anode material is highly indispensable for large-scale energy storage applications. In this study, sugarcane bagasse, one of the most abundant biowaste is chosen as the primary carbon source. Sugarcane bagasse has a great balance of cellulose, hemicellulose, and lignin, which prevents full graphitization of the pyrolyzed carbon but ensures a sufficiently ordered carbon structure for Na+ transport. Sugarcane bagasse carbonized at 950 °C results in a superior crystallinity and demonstrates exceptional electrochemical behavior. Eventually, a comprehensive comparison based on apple biowaste derived hard carbon demonstrates that electrochemical performance is substantially affected by the oxygen content and cellulose content. The comparative electrochemical performance obtained from carbonized sugarcane bagasse and apple biowaste unravels the structural impact of biomass source in interlinking and understanding the sodium storage properties. It also validates biowaste materials have great potential for wide application in sustainable energy storage.
Enhanced Electrochemical Stability of Sulfide Solid Electrolytes by Oxide Substitution for all Solid-State Lithium Ion Batteries
Hanyang University, South Korea
Lithium ion batteries (LIBs) are used in various devices due to their high energy density and long cycle life. Recently, as the electric vehicle (EV) and energy storage system (ESS) market grow, large-scaled lithium ion batteries have been highly attracted. Although liquid electrolyte based battery system has been used for many years, there was still a problem of safety by its flammability.
In the other hand, all solid-state lithium ion batteries (ASSLIBs) have been attracted a lot of attention as a next generation power source because of their enhanced safety, high energy density and wide electrochemical window. Among the solid electrolytes, sulfide based solid electrolytes are expected to suitable electrochemical performance, making favorable contact and high lithium ion conductivity. However, sulfide based solid electrolytes have inferior chemical stability against lithium metal and moisture in the air because of the high reactivity with sulfur. Also, sulfide solid electrolytes react with active cathode material on interface.
Argyrodite structure, Li6PS5X (X = Cl, Br, I), is one of remarkable sulfides electrolytes, it has reported high lithium ion conductivity (> 10-3 S/cm) at room temperature. In order to improve electrochemical performance of the all solid state batteries, solid electrolytes with high electrochemical stability required.
In this study, we focused on improving electrochemical stability of Li6PS5Cl solid electrolyte by oxygen substitution to sulfur. The strong correlation of O incorporation prevents decomposition in interface between electrolyte and cathode active material. X-ray diffraction (XRD) and Raman spectroscopy were performed for structural analysis of electrolyte. To measure the electrochemical stability of each cell, electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) were conducted. As a result, Li6PS(5-x)OxCl solid electrolytes achieved the electrochemical stability in composite cathode.
Application and Its Electrochemical Performances of Li6PS5Cl Solid Electrolyte Coated on the Li[Ni0.6Mn0.2Co0.2]O2 via Liquid Phase Process for All-Solid-State Lithium-Ion Batteries
Division of Materials Science & Engineering, Hanyang University, South Korea
In recent years, with growing environmental concerns, demands for lithium ion batteries (LIBs) as a power source for hydride electric vehicles (HEVs), electric vehicles (EVs) and stationary energy storage systems (ESS) are also rapidly growing. All-solid-state lithium ion batteries (ASSBs) have advantages compared with LIBs using liquid electrolyte such as non-flammability and high energy density.
However, to obtain superior energy density as well as electrochemical performance, ASSBs with poor contact area between active materials and solid electrolyte (SE) need to improve its solid-solid interfacial contact areas. Especially up to 90 % or higher of the active material content, which requires the reduction of solid electrolyte content. it is difficult to prepare a cathode composite with a large contact area between the solid electrolyte and the active materials by a solid process of mixing the two powders. The intimate contact area between solid electrolyte and active materials can be achieved by forming coating layer of the solid electrolyte on the active materials through the liquid phase process since liquids easily cover the surface of a solid powder, which has a big ripple effect in case of high active material content.
Herein, we fabricated the homogeneous composite cathode using the Li6PS5Cl solid electrolyte coated on the NCM 622 via liquid phase process compared with the non-coated NCM 622. Especially, we developed technique for the formation of the homogeneous coating layer on the NCM 622 and evaluated the electrochemical performances.
Aqueous Rechargeable Mixed Ion Batteries
Indian Institute of Science Bengaluru, India
Aqueous rechargeable batteries are potential future alternative energy storage systems due to their higher safety, cost effectiveness and ease of handle. Conventional aqueous metal ion batteries work on the principal of rocking chair mechanism that includes shuttle of one type of ions between anode and the cathode during charge and discharge. Recent developments have been made to merge conventional aqueous batteries into a new class of battery system viz. the mixed ion batteries. The mixed ion batteries involve the shuttle of two types of ions between the anode and cathode materials. The mechanism of operation of these new battery systems is not yet clear. Herein, we discuss this new kind of battery system in a few specific configurations. In the battery configuration dealt here, NaTi2(PO4)3 (NTP) and LiFePO4 (LFP) are employed as anodes and cathodes respectively in combination with mixed ion electrolytes – x-M Li2SO4 : y-M Na2SO4. NaTi2(PO4)3, a NASICON structured material which is widely used as anode in aqueous rechargeable sodium ion batteries, has been synthesized by simple and scalable sol gel method. The structure and morphology of the material has been characterized in detail. The half cell study of NTP in the above mentioned electrolytes are studied by cyclic voltammetry and galvanostatic charge – discharge measurements. The mechanism of Li+ and Na+ insertion into NTP in all the electrolytes have been studied by XPS at different stages of discharge and charge in detail. Further, the full cells are assembled using NTP anode and LFP cathode with all the electrolytes. Initial studies reflect excellent initial discharge capacities, stable cyclability with excellent columbic efficiency. The presentation will also discuss mechanistic and performance studies of mixed ion batteries with other combinations of cathode and anode materials.
Polysulphide Confined Free-Standing Gel Polymer Electrolyte for Shuttle Control in Lithium Sulphur Battery
Indian Institute of Science Bangalore, India
In metal sulphur batteries effective management of polysulphide shuttle is a pressing problem and is responsible for rapid capacity fading and metal-anode poisoning. Majority of the remedies suggested so far involves cathode modifications by providing anchoring sites for the dissolved polysulphides. The main cause of shuttling of polysulphides is its easy dissolution in the liquid electrolyte and a concentration gradient driven migration through the liquid electrolyte to the anode. We propose here a free-standing gel polymer electrolyte which also comprises of a higher order polysulphide in measured amounts. The polysulphide entrapped in the gel during its synthesis provides a buffering effect which should expectedly reduce dissolution of polysulphides from the cathode. Additionally, the gel state of the electrolyte acts as a slower diffusion medium for the polysulphides. Stable battery cyclability depends on the compatibility of the electrolyte with the electrodes in terms of voltage stability window, interface stability as well as other electrochemical properties. Thus, we first demonstrate the favourable properties of the gel matrix without the polysulphides in a lithium symmetric cell. The gel is obtained via in-situ free radical polymerisation of acrylonitrile in the presence of the polymer PEGMEMA and the liquid lithium-salt electrolyte. The stable interpenetrating network showed a high conductivity of 2.4 mS cm-1 and lithium transference number of 0.6. The matrix formed shows a remarkably stable interface and facile dendrite free stripping and plating of lithium over 100 cycles with varied current rates, wide electrochemical stability window making it a promising gel electrolyte for lithium-sulphur system. Incorporation of polysulphide did not drastically degrade the physical properties. Li-S cells were configured with and without polysulfides and charge and discharge characteristics were studied over several cycles.
Effect of Surface Coating on Cathode Active Material by Electrostatic Slurry Spray Deposition for All-solid-state Batteries
Hanyang University, South Korea
Safety matters have been continuously addressed in rechargeable lithium battery industry as more cases with combustion of batteries are being reported. It is attributable to flammable liquid organic electrolytes. All-solid-state batteries(ASSBs), however, have high physical and thermal stability compared to conventional lithium ion batteries by replacing established liquid electrolytes with non-flammable inorganic solid electrolytes. It can also effectively increase specific energy in terms of both gravimetric and volumetric aspects since all parts are compressible into compact size. Although the performance of all-solid-state batteries is yet to be on a par with that of liquid lithium ion batteries, ASSBs have shown considerable potential to be next-generation battery system.
Accordingly, many efforts have been made to combine the advantages of conventional batteries and ASSBs, and some difficulties have remained yet to be solved. One of them is high interfacial resistance between oxide cathode active materials and fast ionic-conductive sulfide electrolytes, which can lead to critical degradation in electrochemical performance. In order to prevent such side reactions, surface modification can be carried out by a variety of methods, such as artificial coatings on electrodes or electrolytes.
In this study, electrostatic slurry spray deposition (ESSD) technique was used in an attempt to apply it as a new coating method. Uniform distribution of coating material is obtained through fine droplets by electrostatic potential. A few kinds of oxides including LiNbO3 were sprayed in the form of slurry with the particles of LiCoO2, a cathode active material. The morphology of the coated particles was investigated using field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) analysis. After fabricating all-solid-state cells with sulfide electrolyte, the electrochemical performance of the cells was evaluated. Also, impedance spectra were measured to identify the expected suppressive effect of coating by ESSD on degradation within cathode layer.
PANI/PEDOT:PSS/MWCNT Composite as Electrode Materials for Supercapacitor Applications
1Cochin University of Science and Technology, India; 2Centre of Excellence in Advanced Materials, Cochin University of Science and Technology, India.; 3Inter-university Centre for Nanomaterials and Devices, Cochin University of Science and Technology, India
Development of clean and sustainable energy sources are essential to reduce the extensive usage of conventional energy sources such as fossil fuels which cause environmental damage. Batteries and supercapacitors are effective energy storage systems which are mandatory for efficient utilization of the generated power from clean energy sources. Supercapacitors (SCs) have got great attention due to its long cycle life and high power density and can be useful for electric power vehicles. Conducting polymers such as polyaniline (PANI) are widely used for energy storage applications due to high conductivity, its chemical stability, cost-effectiveness and ease of synthesis. Here polyaniline poly (3, 4- ethylenedioxythiophene): polystyreneslufonate/multiwalled carbon nanotube (PANI/PEDOT:PSS/MWCNT) composite electrode materials were synthesized by an in-situ polymerization method. Structural, morphological and electrochemical characterization was carried out. PANI/PEDOT:PSS/MWCNT composite shows a specific capacitance of 100 F/g at a current density of 0.5 A/g within 0 to 1 V potential range in 1M lithium perchlorate electrolyte The charge storage in PANI/PEDOT:PSS/MWCNT composite supercapacitor is a combination of pseudocapacitance and electrical double layer capacitance. The composite electrode shows favorable cycling stability after 1000 cycles. The observed results displays that the synthesized ternary composite is an efficient electrode material for supercapacitor applications.
A New Cross-Linked Polymeric Binder as a High-Performance Binder for Si Anodes in Lithium-ion Batteries
National Sun Yat-Sen University, Taiwan
Silicon (Si) with its unprecedented theoretical capacity (4200 mAh g-1) and low working potential (0.5 V vs. Li/Li+) has been extensively explored for future energy storage. A large volume change during the charge–discharge process is a hurdle that needs to be overcome before utilizing its interesting electrochemical properties. Binder, a key component in the electrode structure, plays a key role in maintaining the integrity of electrode components during cycling. Herein, a new polymeric binder was explored as a cross-linkable binder for the Si anode of lithium-ion batteries. This binder was thermally cross-linked to form an elastic material which could relieve the stress incurred during the lithiation and delithiation process. The cross-linked material displayed a high initial charge capacity of ~3300 mAh g-1 and could retain more than 60% of its capacity over 200 cycles at 0.5 C rate. This stable cycle life could be attributed to the three-dimensional polymeric network derived from the cross-linked material. Considering the low cost of the starting materials used and the ease of making the binder, the demonstrated approach in this work could be a viable and cost-effective solution for industrial applications.
A Stable Cathode–Electrolyte Interphase Forming Additive for 5 V-class Material for High-Voltage Lithium-Ion Battery Applications
National Sun Yat-Sen University, Taiwan
Herein, we investigated (pentafluorophenyl)diphenylphosphine (PFPDPP) as a novel, effective, and stable cathode–electrolyte interface-forming additive for high-voltage cathode material. The electrochemical performance was significantly improved with 0.2 wt% PFPDPP-containing electrolyte. The capacity retention with the additive was 71% after 300 cycles of prolonged cycling at the C-rate of 2C with a coulombic efficiency of over 99%, whereas the respective values were 53.4% and 97% for the cell without additive. The effect of PFPDPP on the surface of cathode was investigated via charge–discharge tests, transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy (EIS). EIS measurements showed that PFPDPP forms a low impedance layer on the surface of cathode. Cyclic voltammetry and theoretical density functional theory calculations revealed that PFPDPP undergoes preferential oxidation. The significant improvement in the results can be attributed to the protective cathode–electrolyte interphase formed on cathode surface by PFPDPP.
Evaluation of Mn-Ti-O Framework Based Sodium Ion Battery Electrode Response
Indian Institute of Technology Patna, India
Transition metal oxide framework is well known for its layered structure. Such structures are well accepted as electrode material with established commercial success in the case of lithium ion batteries. However, most of the layered structures have not been studied for application in sodium ion batteries. In fact, larger size of Na+ vis-à-vis Li+ ion makes many layered structure unsuitable for Na+ ion intercalation. Titanates are always favorite candidates for energy storage application due to their wide robust framework which provides easy pathway for ion intercalation without distorting their structure. Hence these structure may be suitable for long term application in storage device. Despite this fact, these materials suffers from very low electronic and ionic conductivity. These issues can be addressed basically in three ways; (i) transition metal (e.g.; Fe, Mn, Ni, Cr) substitution in titanates (ii) surface modification and nanomaterial synthesis for increasing ion intercalation rate (iii) composite formation with high electronic conductors (e.g.; carbonaceous compounds like graphene, activated carbon etc.).
In this report, a new poly-morph based on Mn-Ti-O framework have been prepared and evaluated for its suitability for energy storage applications. Rietveld refinement of x-ray diffraction pattern suggests that the materials belongs to orthorhombic symmetry and can be indexed with space group Pbam(55). Surface morphology was recorded by FESEM showed grains with high aspect ratios non-uniformly distributed throughout the sample. Micro Raman and FTIR spectroscopy suggesting presence of MnO6 and TiO6 in good agreement with the predicted crystallographic structure. The band gap of the prestine material was estimated to be ~1.67 eV through UV-visible spectroscopy techniques. The electrical conductivity of prepared sample was estimated using AC impedance spectroscopy at room temperature and analysed through equivalent circuit modelling. The electrical conductivity of prepared sample was estimated to be ~1.025×10-6 S cm-1.Electrochemical analysis appears encouraging prime facie.
Ni Hydroxide with Si as an Anode Material for Lithium Secondary Batteries
Mie University, Japan
Transition metal oxides and hydroxides show higher capacity than that conventional graphite anode, however, suffer from its poor cycle characteristics. Structural and electrochemical studies of a nanometric iron oxide produced by natural aquatic bacteria, which is an amorphous Fe3+-based oxide containing Si4+ with tube-formed structures found that the presence of Si-O-Fe bond in the structure gave high stability in Fe3+ ⇌ Fe0 conversion reaction . In this study, Si doped nickel hydroxide was studied as a high-capacity anode material for lithium ion batteries. The nickel hydroxides with various Si contents were prepared and characterized by structural and electrochemical investigations.
XRD measurement showed a broad diffraction peaks corresponding to Ni(OH)2 was observed in Si contents of 10% and 15%. Two broad peaks around 34° and 62° appeared in a nanometric iron oxide produced by natural aquatic bacteria and 2-line ferrihydrite (Fh) with amorphous structure were observed when the Si content increase to 20% and 30% [1,2]. FT-IR measurement showed that a peak derived from Ni-O-Si bond was observed around 1,000 cm-1 for all Si-doped samples, indicating the formation of SiO4 tetrahedron links to NiO6 octahedron in the structure. The charge-discharge measurements confirmed that the cyclability was improved with increasing of Si content, and the sample with 20% of Si exhibited higher capacity retention than that of any others. This result indicate that Si-doping stabilize the active material for the conversion reaction by the formation of Si-O covalent bond in the Six/Ni hydroxide structure.
 H. Hashimoto, et al., ACS Appl. Mater. Interfaces, 6 (2014) 5374.
 H. Hashimoto, et al., J. Power Sources, 328 (2016) 503.
Solid-State Synthesis of Ga-doped Lithium Lanthanum Zirconium Oxide as Electrolyte for Lithium-ion Batteries
1National Central University, Taiwan; 2Yuan Ze University, Taiwan; 3National Chiao Tung University, Taiwan; 4CNTouch Co. Ltd, Taiwan
Li7La3Zr2O12(LLZO)-base Li+ conducting oxides are synthesized using a solid-state reaction process and the effects of Ga doping are investigated. With Ga doping, a pure cubic phase of LLZO can be obtained at 900 °C, in contrast to the general synthesis temperature of ~1200 °C for pristine LLZO (without doping). Increasing the synthesis temperature, because of the Li evaporation, impurity phases such as La2Zr2O7 and Li2ZrO3 tend to form, decreasing the Li+ conductivity. The morphology, crystallinity, and ionic conductivity of the Ga-doped LLZO are evaluated using electron microscopy, X-ray diffraction, and electrochemical impedance spectroscopy, respectively. In addition, Ga-doped LLZO, LiTFSI, and poly(ethylene oxide) hybrid electrolyte is fabricated. Decent charge-discharge performance of a Li/LiFePO4 cell using this hybrid electrolyte is demonstrated in the present study.
Topochemical Bottom-Up Synthesis of 2D- and 3D-Sodium Iron Fluoride Frameworks
Jawaharlal Nehru Centre for Advanced Scientific Research, India
A new topochemical bottom-up approach is demonstrated for the first time to synthesize two (2D)- and three dimensional (3D)-sodium iron fluoride frameworks (NaFeF4 and Na2Fe2F7 respectively) through the incorporation of a “structure-stabilizing” agent (i.e. sodium fluoride) into a one-dimensional (1D)-FeF3·3H2O host structure. While the conversion of 1D to 2D framework is enabled by the simultaneous topochemical reactions (dehydration, ion exchange and condensation), the transformation of 2D to 3D structure involves a minor structural rearrangement induced by reductive deintercalation of iron and fluoride ions. All through the structural transformations, the 1D trans-connected chains of FeF6 octahedra originating from FeF3·3H2O host lattice, are retained. The as-prepared 3D-Na2Fe2F7 cathode has shown promising electrochemical properties including the highest intercalation voltage (~3.25 V vs. Na+/Na) with an excellent cycling stability among other iron fluorides that are reported so far. Also it shows reversible capacities above 50 mAh/g for 30 cycles. While NaFeF4 and monoclinic-Na2Fe2F7 phases were synthesized previously at high temperatures, the present approach has not only tailored these materials at relatively low temperatures, but also has harvested a new polymorph of Na2Fe2F7 in orthorhombic structure, which has been achieved by directing the structural connectivity rooting from precursor lattice. In the light of topochemical routes utilized to produce battery cathodes, this bottom-up approach is expected to open new avenues in topochemical synthesis to tailor new higher dimensional alkali ion bearing cathodes based on the low dimensional precursor structures.
Electrochemical Property of the Composite Electrode of Graphene Balls Graphene Oxide for Supercapacitor
Korea University of Technology and Education, South Korea
Inexpensive method was studied to produce the composite electrode of graphene balls (GB) with graphene oxide (GO) for a large surface area. Chemical vapor deposition (CVD) process was used to grow GB on the surface of the composite electrode made of graphene oxide and silicon oxide nanoparticle. GB grow on the surface of silicon oxide and have a large surface area. And GB have a good electrochemical property. Also, GB keep a surface area of GO sheet. Field emission scanning electron microscope and Raman spectroscopy results showed that the defects in the GO surfaces are decreased by GB during the CVD process. The electrochemical characteristics of the electrode investigated through electrochemical impedance spectrometry and cyclic voltammetry tests show that GB-GO composite electrode exhibited better capacitance values than pure GO and more inexpensive than CVD graphene.
Toward High-Power Lithium Ion Phosphate Batteries with Ultrafast Rate Capacity and Stability
1Xi'an Jiaotong University, China; 2Beijing Institute of Nano Energy and Nano Systems, CAS, China
Morphology Controlled LiFePO4@C nanocomposites are prepared by La, Ce co-doping with a hydrothermal method. La, Ce co-doping could not only tailor the particle size, shorten the Li-ion diffusion length, but also enlarge (020) interplanar spacing. Furthermore, the glucose in the solvent forms a uniform and conformal carbon coating on the nano-scaled LiFePO4 particles. Simultaneous, it also fabricates micro carbon spheres serving both as supporting matrix and conductive agent, ensuring a good electronically conductive network throughout the LFP@C nanocomposites. Thus, carrier type of pristine LFP@C transforms from p-type to n-type after La, Ce co-doping, contributing to significant increasing of carrier density and electronic conductivity by a factor of ∼1010 and ~105, respectively. Besides, the enlarged interplanar spacing doubles Li+ diffusion coefficient, facilitating Li+ transport in crystal. With all these advantages, the as-prepared LC-LFP@C-5 shows high specific capacities up to 112.2 mAh g-1 and 95.3 mAh g-1 at ultrahigh current densities of 50 C and 100 C, respectively; after 600 cycles at ultrahigh current densities of 100 C, it enables a specific capacities of 97.1 mAh g-1. Comsol Multiphysics calculation further confirms that La, Ce co-doping enhances Li+ de-intercalation behavior, reduces the overpotential and equalizes Li concentration in the electrode.
Preparation and Electrochemical Characterisation of NASICON Framework Cathode, Na3𝑉2(𝑃𝑂4)3 for Na-ion Batteries
1Iran University of Science and Technology, Iran; 2National University of Singapore, Singapore
Sodium-ion batteries (SIBs) are very attractive and promising for large-scale energy storage applications. The increasing technological improvements in sodium-ion batteries are being driven by the demand for Na-based electrode materials that are resource-abundant and cost-effective. Among the candidate electrode materials, Na3V2(PO4)3 attracted great attention due to its attractive theoretical capacity (117 mAh/g), stable framework structure and excellent ionic conductivity. The moderate voltage window of Na3V2(PO4)3-based SIBs limits the hazard of irreversible side reactions with common electrolytes. However, the practical rate capability and cycling stability of Na3V2 (PO4)3 is limited by its low electronic conductivity. In this work, a facile and simple soft template method was adopted to synthesize Na3V2(PO4)3 materials. Cetyltrimethylammonium bromide (CTAB) is employed in different ratios as both the fuel for the synthesis and as carbon source to synthesize the above material. The primary products are then subjected to a post-heat treatment at 750◦C and 850◦C for 3 and 6 hours, respectively. X-ray Diffraction and Scanning Electron Microscopy, BET Surface area, Solid State NMR and X-ray photoelectron spectroscopy were used to characterize the effect of the preparation method on structure, morphology and physical properties of. The electrochemical performance of the Na3V2(PO4)3 cathodes were evaluated by cyclic voltammetry, galvanostatic cycling with Na as a counter and reference electrodes. Electrochemical cycling studies of Na3V2 (PO4)3 compound showed only one well-defined plateau at 3.4/3.3 V in the voltage range, 2 - 4.0 V vs. Na+. Moreover, Na3V2(PO4)3 prepared by the proposed cost-effective approach delivers superior high rate capability and cycling stability, retaining 90% of the initial capacity after 200 cycles at 1 C rate.