Dry-Milled Microstructure-Controlled Sulfide Electrolytes Enabling Superionic Transport and High-Capacity All-Solid-State Batteries

Abstract

Ball-milled solid-state electrolytes exhibit remarkable room-temperature ionic conductivity exceeding 10 mS cm -1 , yet the mechanisms underlying this exceptional performance remain insufficiently understood. In this study, we systematically explore the influence of filling rate of milling balls (FRB) and ball-to-material ratio (BMR) on the structure-property relationships of Li 5.5 PS 4.5 Cl 0.8 Br 0.7 (LPSCB) argyrodite electrolytes. Optimal conditions were found at 10% FRB and 80:1 BMR, yielding a superior ionic conductivity of 13.3 mS cm -1 and activation energy of 0.28 eV after sintering. Rietveld refinement reveals that milling parameters do not alter the cubic argyrodite phase (F-43m), but significantly affect defect density and residual stress. The enhanced performance arises from defect engineering and stress relaxation, rather than lattice expansion, challenging the conventional view that lattice expansion enhances Li⁺ diffusion. The optimized electrolyte demonstrates stable performance (13-14 mS cm -1 ) across different loadings, highlighting its potential for all-solid-state battery applications. Li 2 TiS 3 (LTS) cathode material was employed to systematically evaluate the electrochemical performance and failure mechanisms of LTS/LPSCB/Li-In all-solid-state lithium batteries (ASSLBs). Electrochemical testing of batteries shows a reversible capacity of 470.6 mAh g -1 and 96.22% capacity retention after 200 cycles under conventional loading (7.6 mg cm -2 ). Impedance analysis suggests that Li⁺ diffusion dominates battery kinetics. Under higher load conditions (14 mg cm -2 ), stable high-energy output is achieved, though accelerated stress growth over 400 cycles leads to interfacial cracking and capacity decay.These findings validate the feasibility of LTS as a cathode material for high-load ASSLBs, emphasizing that effective stress management at the anode interface is essential for ensuring longterm cycling stability in high-energy-density ASSLBs.