Sub-micrometer Li6PS5Cl regulated cathodic Li kinetics in sulfide based all-solid-state batteries

Abstract

The practical applications of all-solid-state batteries (ASSBs) are hindered by poor Li kinetics in electrodes due to the inadequate contact between the cathode active materials (CAMs) and solid-state electrolytes (SSEs). Therefore, improving the contact interface between CAMs and SSEs is necessary to improve the cathodic Li kinetics by increasing the lithium-ion transport sites. To address this issue, sub-micrometer Li₆PS₅Cl (SU-LPSC) particles of high specific areas were utilized to fabricate cathodes with high mass loading. SU-LPSC powders can provide fruitful ionic transport pathways by suppressing inert voids in the electrodes, forming conformal contacts. The reduced porosity contributed to the decrease of the ion tortuosity from 3.91 to 1.77. Therefore, the apparent lithium-ion diffusion coefficient improved by nearly 65%. The SU-LPSC-based cathode/LPSC/Li-In battery exhibits good capacity and cycle performance with different cathode loading amounts. Those assembled batteries utilizing SU-LPSC cathode deliver comparable initial discharge capacities of 197.5 mA h g⁻¹ and an initial coulombic efficiency of 82.4% when cycled at 0.1C, and maintain 93.4% at 0.5C after 200 cycles at room temperature. In comparison to the IN-LPSC cathode battery, the capacity retention after 200 cycles is enhanced by 8.7%. This study investigated the sub-micrometer particle sizes of SSEs to determine the Li kinetics in the cathode, reflecting the good performance of ASSBs, providing a valuable reference for designing high-energy cathodes and optimizing composite cathode structures.