New Oxyhalide Solid Electrolytes with High Lithium Ionic Conductivity >10 mS cm⁻¹for All‐Solid‐State Batteries

Abstract

All‐solid‐state batteries (ASSBs) with inorganic solid electrolytes (SEs) have attracted significant interest as next‐generation energy storage. Halides such as Li3YCl6 are promising candidates for SE because they combine high oxidation stability and deformability. However, the ionic conductivities of halide SEs are not as high as those of other SEs, especially sulfides. Here, we discover new lithium‐metal‐oxy‐halide materials, LiMOCl4 (M=Nb, Ta). They exhibit extremely high ionic conductivities of 10.4 mS cm−1 for M=Nb and 12.4 mS cm−1 for M=Ta, respectively, even in cold‐pressed powder forms at room temperature, which are comparable to or surpass those of organic liquid electrolytes used in lithium‐ion batteries. Bulk‐type ASSB cells using the oxyhalides as the cathode SE demonstrate an outstanding rate capability with a capacity retention of 80 % at 5 C/0.1 C. We believe that the proposed oxyhalides are promising SE candidates for the practical applications of ASSBs.

Amorphous Chloride Solid Electrolytes with High Li-Ion Conductivity for Stable Cycling of All-Solid-State High-Nickel Cathodes

“…The EIS of A-LTC displayed high bulk ionic conduction without the grain boundary (GB) resistance response (Figure 1b ) and interacted with LiCl to sharing common edges or corners within the amorphous matrix, which is different from other metal chlorides (ZrCl 4 , HfCl 4 , YCl 3 , InCl 3 , ScCl 3 and LaCl 3 ) with maintaining crystalline frameworks. [16][17][18]58,59 To compare the Li-ion conductivity of A-LTC with other SEs, we summarized Arrhenius plots of the ionic conductivity of the A-LTC together with typical polymer, 62 glass-ceramic oxide/sulfide, 28,29,60,61 halide, 41,42,44,63 crystalline sulfide 13,14 SEs, and liquid electrolyte 64 in Figure 1c. The Li-ion conductivities and activation energies are also summarized in Table S5.…”

“…(b) Nyquist plots of the EIS measurement results of A-LTC and Bm_LiCl (inset) at 25 °C. (c) Arrhenius plot of ionic conductivities of the A-LTC together with those of crystalline sulfide, organic polymer, glassy oxide/sulfide, halide SEs, and LiPF 6 -based liquid electrolyte with the data adapted with permission from. ,,,,,,,− The A-LTC possesses a low activation energy and superionic conductivity close to that of the state-of-the-art sulfide SEs.…”

Li ion diffusion behavior of Li3OCl solid-state electrolytes with different defect structures: insights from the deep potential model

“…Over the past two decades, some solid electrolytes with ionic conductivity approaching or exceeding that of liquid electrolytes have been prepared, such as Li 7 La 3 Zr 2 O 12 (LLZO), 10 Li 10 GeP 2 S 12 (LGPS), 11 LiSiPSCl, 12 LiNbOCl 4 and LiTaOCl 4 . 13 As more and more types of solid-state electrolytes are developed, in order to investigate the quantitative relationship between the microscopic physical image of ion transport and the ion conductivity and further modulate ion conduction behavior, tremendous research efforts have been made to refine various transport models, ion transport mechanisms and descriptive factors (e.g., structures, migration channel, and diffusion barrier) of solid-state electrolytes. 14 In recent years, Li 3 OX (X = Cl, Br), a lithium-rich antiperovskite (LiRAP) material with a large band gap (46 eV), 15 has been considered as a solid electrolyte material with excellent electrochemical properties.…”

Anion Engineering for Stabilizing Li Interstitial Sites in Halide Solid Electrolytes for All-Solid-State Li Batteries

“…To date, high ionic conductivity (e.g., >1 mS cm –1 ) in halide SEs was achieved by designing a ccp-like anion sublattice (Li 3 YBr 6 , Li 3 InCl 6 , and Li 3 ScCl 6 ), ,, well-known aliovalent substitution (Li 3– x M 1– x III M IV Cl 6 , M III = Sc, In, Y, Yb, Er, and M IV = Zr, Hf), ,− and LiM V OCl 4 (M V = Ta, Nb) . However, these have been valid for halide SEs based on rare-earth elements, limiting the search for a cost-effective halide SE.…”