Protonated Polyaniline-Modified Copper Current Collector for Anode-Free Lithium Metal Battery

The formation of Li dendrites and dead Li, which causes short circuits, continuous side reactions, low Coulombic efficiency (CE), and thermal runaway, significantly hinders the development of anode-free lithium metal batteries (AFLMBs). This study proposes a simple and effective method to construct an HCl-doped polyaniline modification layer on Cu foil (HPC) through chemical polymerization. The polyaniline modification layer exhibits a stable structure and good electrical conductivity after HCl doping, where the protonated and doped imide structure shows excellent lithiophilicity during cycling, promoting uniform Li deposition as a Li ion redistributor. This approach effectively suppresses dendrite growth, enhances the stability of the solid-state interphase at the anode, and extends cell cycle life. As a result, the anode-free half-cell with HPC current collector exhibits reduced overpotential of 20.6 mV and prolonged cycling life over 150 cycles at an areal capacity of 1 mA h cm^-2 and a plating/stripping rate of 1.2 mA cm^-2/2 mA cm^-2. Capacity retention of 63.81% and 74.01% is achieved after 100 cycles in the anode-free (N/P = 0) and anode-less (N/P = 1.6) full cells, respectively. This work creatively introduces a conductive polymer into the AFLMB system, enhancing our understanding of Li plating-stripping regulation strategies and offering new insights into the development of AFLMBs.