CuCl${}_2$-modified lithium metal anode via dynamic protection mechanisms for dendrite-free long-life charging/discharge processes

Lithium metal is considered as an ideal substitute to low-capacity carbon anodes for rechargeable lithium-ion batteries (LIBs) given its ultra-high theoretical specific capacity of 3860 mAh g${}^{-1}$ and the lowest electrochemical potential. However, safety issues stem from the uncontrollable formation and growth of lithium dendrites, which severely plague the practical application of the Li anode. Here, a multi-functional protection layer, prepared by a one-step spin-coating of CuCl${}_2$N-Methyl-2-Pyrrolidone (NMP) solution on a lithium metal surface is constructed. The as-prepared protective layer has a variable porous morphology that consists of a conductive lithium-copper alloy and electrochemically active CuCl, which proactively facilitates the homogeneous diffusion of Li-ions, the elimination of random dendrite nuclei, and even distribution of charge at the Li anode surface, and subsequently the uniform deposition of Li${}^{+}$ ions. Under such a dynamic protection mechanism, the proposed CuCl${}_2$ modified Li electrode can stably cycle more than 1500 h at a current density of 1 mA cm${}^{-2}$ paired with lithium foil. Moreover, the assembled full battery achieves capacity retention of 85.6% even after 2000 cycles at a high rate of 5 C with a LiFePO${}_4$ cathode. This as-proposed dynamic protection mechanism via the incorporation of the electrochemically active component could provide new guidance in the preparation of the safe and high-performance lithium metal anodes. (© 2022 Wiley-VCH GmbH)