Tailoring Solution-Processable Li Argyrodites Li_6+xP_1–xM_xS₅I (M = Ge, Sn) and Their Microstructural Evolution Revealed by Cryo-TEM for All-Solid-State Batteries

Abstract

Owing to their high Li + conductivities, mechanical sinterability, and solution processability, sulfide Li argyrodites have attracted much attention as enablers in the development of highperformance all-solid-state batteries with practicability. However, solution-processable Li argyrodites have been developed only for a composition of Li 6 PS 5 X (X = Cl, Br, I) with insufficiently high Li + conductivities (∼10 −4 S cm −1 ). Herein, we report the highest Li + conductivity of 0.54 mS cm −1 at 30 °C (Li 6.5 P 0.5 Ge 0.5 S 5 I) for solution-processable iodine-based Li argyrodites. A comparative investigation of three iodine-based argyrodites of unsubstituted and Ge-and Sn-substituted solution-processed Li 6 PS 5 I with varied heat-treatment temperature elucidates the effect of microstructural evolution on Li + conductivity. Notably, local nanostructures consisting of argyrodite nanocrystallites in solution-processed Li 6.5 P 0.5 Ge 0.5 S 5 I have been directly captured by cryogenic transmission electron microscopy, which is a first for sulfide solid electrolyte materials. Specifically, the promising electrochemical performances of all-solid-state batteries at 30 °C employing LiCoO 2 electrodes tailored by the infiltration of Li 6.5 P 0.5 Ge 0.5 S 5 I−ethanol solutions are successfully demonstrated.

New Cost‐Effective Halide Solid Electrolytes for All‐Solid‐State Batteries: Mechanochemically Prepared Fe3+‐Substituted Li2ZrCl6

“…The broad peaks for the BM sample reflects the disordered structure. [ 50,51 ] The Raman spectrum of ZrCl 4 showed characteristic signatures of zigzag, polymer‐like chain‐structured [(ZrCl 4/2 )Cl 2 ] n of bridged octahedra; a detailed description is provided in Figure S12, Supporting Information. [ 52 ] In contrast, for both BM‐ and HT‐Li 2 ZrCl 6 , the signatures of bridging octahedra disappeared and two strong peaks at ≈325 and ≈161 cm −1 appeared.…”

Impact of Solvent Treatment of the Superionic Argyrodite Li6PS5Cl on Solid‐State Battery Performance

“…[ 47 ] Unlike Li 3 PS 4 , [ 10,51 ] argyrodites can be dissolved in alcohols for infiltration processes by using ethanol or mixtures of ethanol with ethyl acetate, ethyl propionate, THF, or ACN. [ 16,18–22,51–58 ] As a result of infiltration processing (in alcohols), higher capacities, [ 20,50 ] high reversible capacities, [ 19,22 ] and an improvement in cycling stability and rate capability [ 22 ] were achieved, even though ethanol exposure seems to reduce the conductivity of the argyrodite, with recovery of full conductivity not occurring until heat treatment to high temperatures at which other composite components may not be stable. [ 19,54,56,57 ] For argyrodites treated in ethanol, the grain boundary resistance was reported to increase due to surface residues originating from the solvent.…”

Interfacial Reactions in Inorganic All‐Solid‐State Lithium Batteries

“…For NMC, the well‐dispersed in the Li 3 PS 4 matrix also proves this conclusion [192] . Employing LCO electrodes tailored by the infiltration of Li 6.5 P 0.5 Ge 0.5 S 5 I‐ethanol solutions achieved the promising electrochemical performances of ASSLBs [193] …”

“…[192] Employing LCO electrodes tailored by the infiltration of Li 6.5 P 0.5 Ge 0.5 S 5 I-ethanol solutions achieved the promising electrochemical performances of ASSLBs. [193] Liu et al [194] (Figure 13e). After rapid thermal annealing, the resistance at RT dramatically decreased from 2.5 × 10 4 to 71 Ω cm 2 .…”