A kinetically stable anode interface for Li₃YCl₆-based all-solid-state lithium batteries

Despite their excellent ionic conductivity and electrochemical oxidative stability, the emerging halide-based solid electrolytes suffer from inherent instability toward Li metal anodes. A thick and resistive interface can be formed by continuous reaction between halide electrolytes and Li anodes, leading to high impedance, low coulombic efficiency, and even short circuit of solid-state cells. Here, we report a thin argyrodite (Li₆PS₅Cl) protection layer to avoid the direct physical contact of the Li anode with Li₃YCl₆, a representative halide electrolyte. Li₆PS₅Cl is kinetically stable towards lithium and can also form a good hetero-contact with Li₃YCl₆. Highly stable Li plating/stripping cycling of a symmetric cell with a steady overpotential of 100 mV after 1000 h was demonstrated, compared to severe overpotential build-up to reach 1500 mV after 60 h of the control group. Besides, the LiNi_0.8Co_0.1Mn_0.1O₂/Li full solid-state cell displayed a high initial coulombic efficiency of >87% and a stable lifetime of over 100 cycles. The facile protection of Li₆PS₅Cl provides a universal way to prevent unfavorable interaction at the anode interface and realize high performance all-solid-state Li-metal batteries.