Li10GeP2S12 Solid Electrolyte Research Articles

Role of Halogen Elements in Conductivity and Electrochemical Stability of Sulfide Based Solid Electrolytes

All-solid-state batteries (ASSBs) are a promising candidate for future energy storage technology with better safety and higher energy density [1]. Safety of solid state batteries come from solid electrolytes used instead of organic liquid electrolytes in conventional Li-ion batteries. The various types of solid electrolytes have already been reported for SSBs which can be divided into oxides, sulfides, halides and polymers based on their properties, advantages and disadvantages [2]. Among them, sulfide based solid electrolytes have advantages over other due to high conductivity and ductile nature of sulfides [3]. The discovery of Li10GeP2S12 solid electrolyte called LGPS structured sulfide electrolyte have shown great potential to replace liquid electrolyte as ionic conductivity of LGPS was found 1.2×10-2 S cm-1 at room temperature comparable to the conductivity of organic liquid electrolyte [4]. However, Li10GeP2S12 electrolyte suffers with poor cyclability in solid state batteries due to reduction of Ge+4 ions to Ge0, and instable against lithium metal anode [5, 6].The solid electrolytes (SEs) with high conductivity and better stability against lithium metal are most important requirements for successful commercialization of solid state battery (SSB) technology. Therefore, in the search for new SEs with above mentioned qualities, halogen elements (Cl, Br, I) are explored in Li-P-S-O system to prepare Li10GeP2S12 (LGPS) structured SEs. In all prepared SEs, LPSOBr and LPSOI compositions show highest conductivities of 0.55 mS cm-1 and 0.67 mS cm-1 at 25 °C. The phase identification of newly synthesized solid electrolytes is done by X-ray diffractometer technique along with Rietveld refinement analysis. The conductivity of prepared solid electrolytes is determined by electrochemical impedance spectroscopy. These similar compounds also show superior stability against lithium metal in symmetric cells (Li/Ses/SE) as well as in full SSB cells (NCA/SEs/graphite) tested with LiNi0.8Co0.15Al0.05O2 cathode and graphite anode. These compounds also show 5 times higher stability in ambient environment conditions as compared to non-doped LPSO compound.

Homogeneous Fluorine Doping toward Highly Conductive and Stable Li10GeP2S12 Solid Electrolyte for All-Solid-State Lithium Batteries.

The unique structure and exceptionally high lithium ion conductivity over 10mScm-1 of Li10GeP2S12 have gained extensive attention in all-solid-state lithium batteries. However, its poor resistivity to moisture and chemical/electrochemical incompatibility with lithium metal severely impede its practical application. Herein, a fluorine functionalized Li10GeP2S12 is synthesized by stannous fluoride doping and employed as a monolayer solid electrolyte to realize stable all-solid-state lithium batteries. The atomic-scale mechanism underlying the impact of fluorine doping on both moisture and electrochemical stability of Li10GeP2S12 is revealed by density functional theory calculations. Fluorine surface doping significantly reduces surface hydrophilicity by electronic regulation, thereby retarding the hydrolysis reaction of Li10GeP2S12. After exposed to a relative humidity of 35%-40% for 20min, the ionic conductivity of Li9.98Ge0.99Sn0.01P2S11.98F0.02 maintains as high as 2.21mScm-1, nearly one order of magnitude higher than that of Li10GeP2S12 with 0.31mScm-1. Meanwhile, bulk doping of highly electronegative fluorine promotes the formation of lithium vacancies in the Li10GeP2S12 system, thus allowing stable lithium plating/stripping in Li | Li symmetric batteries, boosting a critical current density reaching 2.1mAcm-2. The LiCoO2 | lithium all-solid-state batteries display improved cycling stability and rate capability, showing 80.1% retention after 600 cycles at 1C.

New Low Cost Sulfide Electrolytes for All Solid State Batteries

The low cost, safe and high energy storage technology is needed to ensure a continuous energy supply from renewal energy sources. However, current Li-ion batteries (LiBs) are facing challenges to fulfil the safety and high energy and power demands of fast-growing market of electric vehicles (EVs). In particular, liquid organic electrolytes used in conventional LIBs have raised the safety issues due to serious fire risk. Solid state batteries (SSBs) are considered to provide better safety as compared to LIBs because of solid electrolytes (SEs) are used in SSBs instead of flammable organic liquid based electrolytes [1-4].The various types of solid electrolytes have already been reported for SSBs which can be divided into oxides, sulfides, halides and polymers based on their properties, advantages and disadvantages [5]. Among these solid electrolytes, sulfide solid electrolytes have advantages over other due to high conductivity and ductile nature of sulfides [6]. The discovery of Li10GeP2S12 solid electrolyte called LGPS structured sulfide electrolyte have shown great potential to replace liquid electrolyte as ionic conductivity of LGPS was found 1.2×10-2 S cm-1 at room temperature comparable to the conductivity of organic liquid electrolyte [7]. However, Li10GeP2S12 electrolyte suffers with poor cyclability in solid state batteries due to reduction of Ge+4 ions to Ge0, and instable against lithium metal anode. Moreover, germanium (Ge) is a rare and expensive element, which limits the industrial application of Li10GeP2S12 [8, 9].Therefore, in the present work, we have developed LGPS structured based new Ge free solid electrolytes with high conductivity and better electrochemical stability. The phase identification of newly synthesized solid electrolytes is done by X-ray diffractometer technique along with Rietveld refinement analysis. The conductivity of prepared solid electrolytes is determined by electrochemical impedance spectroscopy. The ionic conductivity of newly synthesised electrolytes has reached upto 0.67 mS cm-1 at room temperature. The electrochemical analysis of prepared solid electrolytes is done using Li-metal in both side (in symmetric cell) as well as using standard cathode and anode materials (full cell).

Microstructure Control of LiCoO2‐Li10GeP2S12 Composite Cathodes by Adjusting the Particle Size Distribution for the Enhancement of All‐Solid‐State Batteries

AbstractMicrostructure control of composite electrodes comprising active materials and solid electrolytes is imperative to achieve sufficient ion‐ and electron‐conductive pathways for the development of all‐solid‐state Li ion batteries. Here, we synthesized Li10GeP2S12 solid electrolytes with various particle size distributions by milling and filtering. Impedance spectroscopy revealed that the ionic conductivities in the bulk were hardly changed by the synthetic processes. This enabled us to investigate only the microstructure effects on the electrochemical properties of the composite electrodes. Microscopic and electrochemical tests of the LiCoO2‐Li10GeP2S12 composite cathodes clarified that the size distributions of the Li10GeP2S12 drastically affected the microstructures in the composite cathodes, such as contacts at interfaces and voids between particles. The size distributions also contributed to the appropriate ratio of LiCoO2 to Li10GeP2S12 for superior charge/discharge properties. The (de)intercalation reversibly proceeded in the composite cathode using the filtered Li10GeP2S12 even though the ratio of Li10GeP2S12 decreased from 50 % to 30 % in volume. This study demonstrated the possibility of high‐energy‐density composite cathodes for all‐solid‐state batteries by control of microstructures in composite electrodes.

Disentangling the Li-Ion transport and Boundary Phase Transition Processes in Li10 GeP2 S12 Electrolyte by In-Operando High-Pressure and High-Resolution NMR Spectroscopy.

Li-ion transport and phase transition of solid electrolytes are critical and fundamental issues governing the rate and cycling performances of solid-state batteries. In this work, in-operando high-pressure nuclear magnetic resonance (NMR) spectroscopy for the solid-state battery is developed and applied, in combination with 6 Li-tracer NMR and high-resolution NMR spectroscopy, to investigate the Li10 GeP2 S12 electrolyte under true-to-life operation conditions. The results reveal that the Li10 GeP2 S12 phase may become more disordered and a large amount of conductive metastable β-Li3 PS4 as the glassy matrix in the electrolyte transforms into less conductive phases, mainly γ-Li3 PS4 , when high current densities (e.g., ≥0.5mA cm-2 ) are applied to the electrolyte. The overall Li-transport also varies and shows a tendency of boundary phases and Li10 GeP2 S12 synergistic dominant conduction at high currents. Accordingly, a mechanism of structural change induced by stress variation due to the drastic morphological change during Li-In alloying at high currents, and the local Li+ diffusion coefficient discrepancy is proposed. These new findings of Li-ion transport and boundary phase transition in Li10 GeP2 S12 solid electrolyte under high-pressure and high current density are first reported and will help provide previously lacking insights into the relationship of structure and performance of Li10 GeP2 S12 .

Fluorinated Li10 GeP2 S12 Enables Stable All-Solid-State Lithium Batteries.

The instability of Li10 GeP2 S12 toward moisture and that toward lithium metal are two challenges for the application in all-solid-state lithium batteries. In this work, Li10 GeP2 S12 is fluorinated to form a LiF-coated core-shell solid electrolyte LiF@Li10 GeP2 S12 . Density-functional theory calculations confirm the hydrolysis mechanism of Li10 GeP2 S12 solid electrolyte, including H2 O adsorption on Li atoms of Li10 GeP2 S12 and the subsequent PS4 3- dissociation affected by hydrogen bond. The hydrophobic LiF shell can reduce the adsorption site, thus resulting in superior moisture stability when exposing in 30% relative humidity air. Moreover, with LiF shell, Li10 GeP2 S12 shows one order lower electronic conductivity, which can significantly suppress lithium dendrite growth and reduce the side reaction between Li10 GeP2 S12 and lithium, realizing three times higher critical current density to 3mA cm-2 . The assembled LiNbO3 @LiCoO2 /LiF@Li10 GeP2 S12 /Li battery exhibits an initial discharge capacity of 101.0 mAh g-1 with a capacity retention of 94.8% after 1000 cycles at 1 C.

A gradient oxy-thiophosphate-coated Ni-rich layered oxide cathode for stable all-solid-state Li-ion batteries

High-energy Ni-rich layered oxide cathode materials such as LiNi0.8Mn0.1Co0.1O2 (NMC811) suffer from detrimental side reactions and interfacial structural instability when coupled with sulfide solid-state electrolytes in all-solid-state lithium-based batteries. To circumvent this issue, here we propose a gradient coating of the NMC811 particles with lithium oxy-thiophosphate (Li3P1+xO4S4x). Via atomic layer deposition of Li3PO4 and subsequent in situ formation of a gradient Li3P1+xO4S4x coating, a precise and conformal covering for NMC811 particles is obtained. The tailored surface structure and chemistry of NMC811 hinder the structural degradation associated with the layered-to-spinel transformation in the grain boundaries and effectively stabilize the cathode|solid electrolyte interface during cycling. Indeed, when tested in combination with an indium metal negative electrode and a Li10GeP2S12 solid electrolyte, the gradient oxy-thiophosphate-coated NCM811-based positive electrode enables the delivery of a specific discharge capacity of 128 mAh/g after almost 250 cycles at 0.178 mA/cm2 and 25 °C.

Li10GeP2S12 solid electrolytes synthesised via liquid-phase methods.

Li10GeP2S12 solid electrolytes for all-solid-state batteries were synthesised through liquid-phase shaking, which is a suspension synthesis method, in 1 d. Additionally, Li10GeP2S12 solid electrolytes were prepared in 7.5 h, which is the fastest synthesis time, through solution synthesis using excess sulfur and a mixed solvent of acetonitrile, tetrahydrofuran, and ethanol. These Li10GeP2S12 solid electrolytes exhibited an ionic conductivity of 1.6 × 10-3 S cm-1, which is the highest ionic conductivity of previous studies of liquid phase synthesis. Therefore, Li10GeP2S12 solid electrolytes with high ionic conductivity can be rapidly synthesised via liquid-phase methods.

Dual‐functional ZnO/LiF layer protected lithium metal for stable Li10GeP2S12‐based all‐solid‐state lithium batteries

AbstractAll‐solid‐state lithium battery has become one of the most promising secondary batteries due to their high energy density and excellent safety. However, the growth of lithium dendrites and side reactions between lithium metal and solid electrolytes hinder the practical application of all‐solid‐state lithium batteries. Herein, a dual‐functional layer of ZnO and LiF is fabricated at the interface between lithium metal and Li10GeP2S12 solid electrolyte by a magnetic sputtering technique. The ZnO/LiF dual‐functional layer can suppress severe Li10GeP2S12/lithium metal interface side reactions and has a high interface energy against lithium which can block the growth of lithium dendrites. The symmetric cell of Li@ZnO/LiF‐Li10GeP2S12‐Li@ZnO/LiF demonstrates stable lithium plating/striping cycling for 2000 h with a small overpotential of 200 mV at 0.1 mA cm−2 and 0.1 mAh cm−2. The full cell of Li@ZnO/LiF‐Li10GeP2S12‐LiCoO2@LiNbO3 shows stable cycling stability for 500 cycles with a high reversible specific capacity of 80 mAh g−1 at 1.0 C.

First-principles study on selenium-doped Li10GeP2S12 solid electrolyte: Effects of doping on moisture stability and Li-ion transport properties

Improving moisture stability without degrading the ionic conductivity of Li10GeP2S12 (LGPS) based solid-state electrolytes (SSEs) is one of the key issues in developing all-solid-state lithium batteries. Herein, we report the reactivity of the LGPS surface towards H2O, subsequent hydrolysis reactions for the H2S formation, and effective methods to suppress the H2S evolution on the LGPS surface using density functional theory (DFT) calculations. The pristine LGPS surface is highly unstable towards H2O at room temperature, where H2O dissociation occurs spontaneously. However, the H2O adsorption and its activation are weakened upon the Se substitution on the LGPS surface. By doping the Se atom on LGPS, the H2S evolution can be suppressed and significantly improve the chemical stability of the LGPS surface. In addition, we predict the Li+ ion transport properties of both pristine and Se-doped LGPS compounds using ab initio molecular dynamics (AIMD) simulations. The Se-doped LGPS material has a similar bandgap to pristine LGPS; it can have similar decomposition products and low electronic conductivity. The predicted ionic conductivity of Se-doped LGPS is found to be slightly lower than the pristine. We propose replacing sulfur with Se atom as an effective strategy to improve the moisture stability of the LGPS compound.

A Nanoscale Design Approach for Enhancing the Li-Ion Conductivity of the Li10GeP2S12 Solid Electrolyte.

The discovery of the lithium superionic conductor Li10GeP2S12 (LGPS) has led to significant research activity on solid electrolytes for high-performance solid-state batteries. Despite LGPS exhibiting a remarkably high room-temperature Li-ion conductivity, comparable to that of the liquid electrolytes used in current Li-ion batteries, nanoscale effects in this material have not been fully explored. Here, we predict that nanosizing of LGPS can be used to further enhance its Li-ion conductivity. By utilizing state-of-the-art nanoscale modeling techniques, our results reveal significant nanosizing effects with the Li-ion conductivity of LGPS increasing with decreasing particle volume. These features are due to a fundamental change from a primarily one-dimensional Li-ion conduction mechanism to a three-dimensional mechanism and major changes in the local structure. For the smallest nanometric particle size, the Li-ion conductivity at room temperature is three times higher than that of the bulk system. These findings reveal that nanosizing LGPS and related solid electrolytes could be an effective design approach to enhance their Li-ion conductivity.

A mechanistic investigation of the Li10GeP2S12|LiNi1-x-yCoxMnyO2 interface stability in all-solid-state lithium batteries

All-solid-state batteries are intensively investigated, although their performance is not yet satisfactory for large-scale applications. In this context, the combination of Li10GeP2S12 solid electrolyte and LiNi1-x-yCoxMnyO2 positive electrode active materials is considered promising despite the yet unsatisfactory battery performance induced by the thermodynamically unstable electrode|electrolyte interface. Here, we report electrochemical and spectrometric studies to monitor the interface evolution during cycling and understand the reactivity and degradation kinetics. We found that the Wagner-type model for diffusion-controlled reactions describes the degradation kinetics very well, suggesting that electronic transport limits the growth of the degradation layer formed at the electrode|electrolyte interface. Furthermore, we demonstrate that the rate of interfacial degradation increases with the state of charge and the presence of two oxidation mechanisms at medium (3.7 V vs. Li+/Li < E < 4.2 V vs. Li+/Li) and high (E ≥ 4.2 V vs. Li+/Li) potentials. A high state of charge (>80%) triggers the structural instability and oxygen release at the positive electrode and leads to more severe degradation.

Stable Cycling Lithium-Sulfur Solid Batteries with Enhanced Li/Li10GeP2S12 Solid Electrolyte Interface Stability.

We herein explore a facile and straightforward approach to enhance the interface stability between the lithium superionic conducting Li10GeP2S12 (LGPS) solid electrolyte and Li metal by employing ionic liquid such as 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)/ N-methyl- N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR13TFSI) as the interface modifier. The results demonstrated the presence of 1 M LiTFSI/PYR13TFSI ionic liquid; the interface stability at the electrode/solid electrolyte (i.e., Li/LGPS) was improved remarkably by forming an in situ solid electrolyte interphase (SEI) layer. As a result, an effectively reduced interfacial resistance from 2021 to 142 Ω cm2 and stable Li stripping/plating performance (over 1200 h at 0.038 mA cm-2 and 1000 h at 0.1 mA cm-2) were achieved in the Li/LGPS/Li symmetric cells. On this basis, the Li-S solid-state batteries were further architectured with one of the S@C composite [where C is the ketjen black carbon (KBC) or PBX 51-type activated carbon (PBX51C) or multiwalled carbon nanotubes (MCNTs)] cathode and the LGPS solid electrolyte. The batteries with S@KBC electrodes delivered an excellent discharge/charge performance with a high initial discharge capacity of 1017 mA h g-1 and better stability than those of the batteries with the S@PBX51C and S@MCNTs electrodes. High surface area, unique beneficial pore structure, and better particle dispersion of sulfur in the S@KBC composite facilitate high sulfur utilization and also increase the intimate contact between the electrode and LGPS solid electrolyteduring the discharge/charge process.

LiNbO3-coated LiNi0.8Co0.1Mn0.1O2 cathode with high discharge capacity and rate performance for all-solid-state lithium battery

Abstract In order to obtain high power density, energy density and safe energy storage lithium ion batteries (LIB) to meet growing demand for electronic products, oxide cathodes have been widely explored in all-solid-state lithium batteries (ASSLB) using sulfide solid electrolyte. However, the electrochemical performances are still not satisfactory, due to the high interfacial resistance caused by severe interfacial instability between sulfide solid electrolyte and oxide cathode, especially Ni-rich oxide cathodes, in charge-discharge process. Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) material at present is one of the most key cathode candidates to achieve the high energy density up to 300 Wh kg−1 in liquid LIB, but rarely investigated in ASSLB using sulfide electrolyte. To design the stable interface between NCM811 and sulfide electrolyte should be extremely necessary. In this work, in view of our previous work, LiNbO3 coating with about 1 wt% content is adopted to improve the interfacial stability and the electrochemical performances of NCM811 cathode in ASSLB using Li10GeP2S12 solid electrolyte. Consequently, LiNbO3-coated NCM811 cathode displays the higher discharge capacity and rate performance than the reported oxide electrodes in ASSLB using sulfide solid electrolyte to our knowledge.

Investigation of the Li-ion conduction behavior in the Li10GeP2S12 solid electrolyte by two-dimensional T1-spin alignment echo correlation NMR

Li10GeP2S12 (LGPS) is the fastest known Li-ion conductor to date due to the formation of one-dimensional channels with a very high Li mobility. A knowledge-based optimization of such materials for use, for example, as solid electrolyte in all-solid-state batteries requires, however, a more comprehensive understanding of Li ion conduction that considers mobility in all three dimensions, mobility between crystallites and different phases, as well as their distributions within the material. The spin alignment echo (SAE) nuclear magnetic resonance (NMR) technique is suitable to directly probe slow Li ion hops with correlation times down to about 10−5 s, but distinction between hopping time constants and relaxation processes may be ambiguous. This contribution presents the correlation of the 7Li spin lattice relaxation (SLR) time constants (T1) with the SAE decay time constant τc to distinguish between hopping time constants and signal decay limited by relaxation in the τc distribution. A pulse sequence was employed with two independently varied mixing times. The obtained multidimensional time domain data was processed with an algorithm for discrete Laplace inversion that does not use a non-negativity constraint to deliver 2D SLR–SAE correlation maps. Using the full echo transient, it was also possible to estimate the NMR spectrum of the Li ions responsible for each point in the correlation map. The signal components were assigned to different environments in the LGPS structure.

Degradation Mechanisms at the Li10GeP2S12/LiCoO2 Cathode Interface in an All-Solid-State Lithium-Ion Battery.

All-solid-state batteries (ASSBs) show great potential for providing high power and energy densities with enhanced battery safety. While new solid electrolytes (SEs) have been developed with high enough ionic conductivities, SSBs with long operational life are still rarely reported. Therefore, on the way to high-performance and long-life ASSBs, a better understanding of the complex degradation mechanisms, occurring at the electrode/electrolyte interfaces is pivotal. While the lithium metal/solid electrolyte interface is receiving considerable attention due to the quest for high energy density, the interface between the active material and solid electrolyte particles within the composite cathode is arguably the most difficult to solve and study. In this work, multiple characterization methods are combined to better understand the processes that occur at the LiCoO2 cathode and the Li10GeP2S12 solid electrolyte interface. Indium and Li4Ti5O12 are used as anode materials to avoid the instability problems associated with Li-metal anodes. Capacity fading and increased impedances are observed during long-term cycling. Postmortem analysis with scanning transmission electron microscopy, electron energy loss spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy show that electrochemically driven mechanical failure and degradation at the cathode/solid electrolyte interface contribute to the increase in internal resistance and the resulting capacity fading. These results suggest that the development of electrochemically more stable SEs and the engineering of cathode/SE interfaces are crucial for achieving reliable SSB performance.

A facile strategy to improve the electrochemical stability of a lithium ion conducting Li10GeP2S12 solid electrolyte

A super solid electrolyte of Ba-substituted Li10GeP2S12 is designed and fabricated to achieve high electrochemical stability. Among the Ba-substituted Li10GeP2S12 solid electrolytes, the composition of Li9.4Ba0.3GeP2S12 exhibits the highest ionic conductivity of 7.04×10−4Scm−1 with an activation energy of 28.27kJmol−1 at 25°C. The electrochemical window of Li9.4Ba0.3GeP2S12 is between 0 and 6V (vs. Li), which is higher than the typical 5V window of Li10GeP2S12. As compared with Li10GeP2S12, Li9.4Ba0.3GeP2S12 demonstrates a significantly reduced polarization and a better cycle stability though its ionic conductivity is slightly lower than that of the former. The electrochemical stability of Ba-substituted Li10GeP2S12 can be attributed to the structural stability resulting from the stable interaction between Ba2+ and S2− in the structure.

Bulk-Type All Solid-State Batteries with 5 V Class LiNi0.5Mn1.5O4 Cathode and Li10GeP2S12 Solid Electrolyte

All solid-state batteries are of key importance in the development of next-generation energy storage devices with high energy density. Herein, we report the fabrication and operation of bulk-type 5 V-class all solid-state batteries consisting of LiNi0.5Mn1.5O4 cathode, Li10GeP2S12 solid-electrolyte, and Li metal anode. The 1st discharge capacity is about 80 mAh g–1 with an average voltage of 4.3 V. The discharge capacity gradually decreases during the subsequent cycles. X-ray diffraction and electrochemical impedance spectroscopy measurements reveal that the capacity fading results from the growth of a resistive interfacial layer on the cathode composite. The development of suitable conductive additive and sulfide solid electrolyte materials is essential for the development of high-voltage all solid-state batteries.

Membranes for rechargeable lithium sulphur semi-flow batteries

The aim of achieving high-energy, long-life, safe and low cast storage batteries has brought tremendous scientific attention in the last decade, resulting in significant improvements in the stored energy of cathodes and anodes particularly in lithium-based battery technology. However, presently available lithium-ion technology cannot satisfy the increasing demand for energy density. Li–S battery is a typical example, which can offer theoretically a fivefold increase in energy density compared with conventional lithium rechargeable batteries. Despite significant advances, there are challenges to its wide-scale implementation, which include dissolution of intermediate polysulphide reaction species into the electrolyte when liquid polysulphide is used as cathodes. Another problem is preparation of polysulphides. Here we report a novel approach to replace the liquid electrolyte with solid lithium conducting membranes, Argyrodite (Li6PS5X(X = Cl,Br)) and Li10GeP2S12 solid electrolytes to mitigate the problem. Among the three solid electrolyte membranes Li10GeP2S12 exhibited high first discharge specific capacity of 1435 (±3) mAh g−1 at 0.5 C rate.

Effect of surface modification and oxygen deficiency on intercalation property of lithium nickel manganese oxide in an all-solid-state battery

LiNbO3-coated LiNi0.5Mn1.5O4 powders were synthesized by a sol–gel method, and their intercalation property as a cathode material was investigated using all-solid-state batteries with Li10GeP2S12 solid electrolyte and In–Li metal anode. The LiNbO3 coating delivered reversible lithium intercalation of LiNi0.5Mn1.5O4 through an electrochemical interface with the Li10GeP2S12. Oxygen-deficient LiNi0.5Mn1.5O4−δ with a higher electronic conductivity than LiNi0.5Mn1.5O4 improved the intercalation activity. An all-solid-state battery consisting of 3wt.%-LiNbO3-coated LiNi0.5Mn1.5O4−δ/Li10GeP2S12/In–Li exhibited a discharge capacity of 80mAhg−1 at the first cycle with an average discharge voltage of 4.1V (vs. In-Li), which demonstrates the possibility of 5V class all-solid-state batteries with a high voltage spinel cathode.