Harnessing Liquid Metals with In Situ Polymerized Electrolyte for Anode‐Free Lithium Metal Batteries

Abstract To enhance safety and energy density in conventional Li‐ion batteries, anode‐free or zero‐lithium configurations using only a current collector (CC) in the anode have emerged. However, challenges including rapid Li dendrite growth, low Coulombic efficiency, safety concerns, and thickness issues hinder the practical use of anode‐free batteries (AFBs) with liquid electrolytes (LEs) or solid electrolytes (SEs). Herein, potential AFBs using an anode current collector coated with a liquid metal (LM)@C nanocomposite with an in situ polymerized electrolyte (PE) are reported. Interestingly, LM nanoparticles added to the composite layer on CC play a crucial role in promoting uniform Li plating/stripping behavior through a self‐healing mechanism, along with reversible liquid–solid–liquid phase transitions caused by alloying and de‐alloying of Li and LMs. Furthermore, incorporating in situ polymerized electrolytes stabilizes LMs by preventing the agglomeration of LM nanoparticles, resulting in significantly improved cell performance compared to other conventional LEs. A systematical model study with ex situ analysis unveils the synergetic effects between LMs and PE, along with elucidating the mechanism of in situ polymerization and Li‐LMs reactions. The investigation contributes valuable insights for future studies on practical applications of AFBs using polymer electrolytes and composite interlayers.