Advancing anode-less lithium metal batteries: ZnF2 modification and in situ structural regulation for enhanced performance

Abstract

Lithium metal anodes tend to form non-uniform Li deposition that causes dendrite growth during cycling. Meanwhile, the deposition and dissolution of lithium metal often results in the continuous formation and breakdown of the SEI. Additionally, the use of thick lithium metal often results in an excessive inventory of lithium, which diminishes the energy advantage of lithium metal. Fabricating thin lithium foils is challenging owing to the low mechanical strength of lithium metal. To address these issues, we employed an in situ structural regulation strategy to prepare high-performance lithium metal batteries. The mechanical strength of the prepared LiF@LiZn10/Li foil was significantly enhanced, allowing it to be thinned down to a thickness of 5 μm, accompanied with great air stability. Moreover, the in situ formation of LiZn alloys improved Li-deposition behavior. Furthermore, we demonstrated the participation of LiF particles in the in situ formation of the SEI, which facilitated Li⁺-transport kinetics. The LiF@LiZn10/Li electrode demonstrated significantly enhanced cycling performance by synergistically improving Li-deposition behavior and optimizing the SEI layer in situ. The LiF@LiZn10/Li foil electrode exhibited a long cycling life of over 1300 h at 1 mA cm⁻² and 1 mA h cm⁻². When coupled with a commercial LiFePO₄ cathode (3.3 mA h cm⁻²), the LiFePO₄‖LiF@LiZn10/Li cell exhibited a cycle life approximately thrice that of the cells with LMBs. This work provides a novel strategy to optimize LMAs for next-generation LMBs.