An all-in-one approach for sulfide solid electrolyte with bidirectional stabilization shells enabling 4.6 V all-solid-state lithium batteries

The narrow electrochemical window of sulfide electrolytes can lead to different failure mechanisms at the interfaces of the cathode and anode sides. The introduction of distinct modification strategies for the cathode and anode sides increases the complexity of the fabrication process for sulfide-based all-solid-state lithium batteries (ASSLBs). In this work, an integrated modification strategy was employed by introducing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) shells during the wet refinement process of Li₆PS₅Cl (LPSC), which successfully in situ constructed robust fluorinated interfaces on both the cathode and anode sides simultaneously. On the lithium anode side, the decreased electronic conductivity of LiTFSI@LPSC and the generation of fluorinated interface effectively suppressed lithium dendrite growth, which was further confirmed by the Density-Functional Theory (DFT) calculations. As a result, the Li|LiTFSI@LPSC|Li cell realized the critical current density up to 1.6 mA cm⁻² and stable cycling performance over 1500 h at 0.2 mA cm⁻². On the cathode side, the LiTFSI@LPSC not only enhanced Li⁺ transport within the composite cathode, but also the LiTFSI shell in situ decomposed into LiF based cathode electrolyte interphase (CEI). The capacity retention achieved 98.6 % after 500 cycles at 2C with LiNi_0.83Co_0.11Mn_0.06O₂ (NCM83) at high cut-off voltage of 4.6 V. The functionalized LiTFSI@LPSC facilitates comprehensive, all-in-one interfacial modification for both the anode and cathode sides, significantly simplifying the interface engineering in sulfide-based ASSLBs while delivering exceptional electrochemical performance.