Tailored Cathode Composite Structure Enables Long Cycle Life at Low-Pressure for Sulfide All-Solid-State Batteries

Despite all-solid-state batteries (ASSBs) currently attracting significant attention due to their potential to offer higher safety and energy density in energy storage system with, their practical application is hindered by reduced electrochemical performance at low pressure. In this work, we tailor LiNi_0.8Mn_0.8Co_0.1O₂ (NCM811) cathode composite structure by using fine particle size Li₆PS₅Cl (LPSC), which is prepared by roll-mixing the coarse-electrolyte with a toluene solution. We demonstrate that the fine-LPSC-cathode composite achieves a uniform distribution of the solid-state electrolyte (SSE) on the surface of each NCM811 particle, providing good interfacial contact for efficient Li⁺ transport percolation. Moreover, the low tortuosity in the fine-LPSC -cathode composite facilitates the Li⁺ mobility during (de)lithiation. In particular, these features result in lower charge transfer resistance in the fine-LPSC-cathode composite, effectively suppressing structural distortion and interface deterioration during prolonged cell cycling under low pressure conditions. Therefore, the fine-LPSC-cathode composite enables impressive cyclability performance at a modest stack pressure of 2 MPa in ASSBs compared to the coarse-LPSC-cathode composite, which is important for ASSBs application.