Composite Lithium Protective Layer Formed In Situ for Stable Lithium Metal Batteries

Lithium metal is considered as the ideal anode for next-generation rechargeable batteries due to its highest theoretical specific capacity and lowest electrochemical potential. However, lithium dendrite growth during lithium deposition could lead to a short circuit and even cause severe safety issues. Here, we use solid-state electrolyte Li3InCl6 as an additive in nonaqueous electrolytes because of its high ionic conductivity (10(-3) to 10(-4) S cm(-1)) and good electrochemical stability. It is found that Li3InCl6 can in situ react with metallic lithium to form a ternary composite solid electrolyte interphase (SEI) consisting of a Li-In alloy, LiCl, and codeposited Li3InCl6. The composite SEI can effectively suppress Li dendrite growth and thereby maintain stable long-term cycling performance in lithium metal batteries. The protected lithium electrode exhibits stable cycling performance in a symmetric Li|Li battery for nearly 1000 h at a current density of 1 mA cm(-2). Besides, the full battery with a LiFePO4 cathode and a metallic lithium anode delivers a stable capacity of 140.6 mA h g(-1) for 500 cycles with a capacity retention of 95%. The Li vertical bar S battery with Li3InCl6-added LiTFSI in 1,3-dioxolane/1,2-dimethoxyethane electrolyte also shows significant improvement in capacity retention at 0.5 C. This work demonstrates an effective approach to design dendrite-free metal anodes.

Automated summary

The addition of Li3InCl6 in nonaqueous electrolytes can form a ternary composite solid electrolyte interphase (SEI) that effectively suppresses lithium dendrite growth in lithium metal batteries, maintaining stable long-term cycling performance. This approach leads to dendrite-free metal anodes, as demonstrated in symmetric Li|Li batteries and full batteries with a LiFePO4 cathode, achieving a stable capacity retention of 95% after 500 cycles. Furthermore, the Li vertical bar S battery with Li3InCl6-added LiTFSI in 1,3-dioxolane/1,2-dimethoxyethane electrolyte shows significant improvement in capacity retention at 0.5 C.