In Situ Electrochemical Polymerization of Cathode Electrolyte Interphase Enabling High‐Performance Lithium Metal Batteries

Abstract Lithium metal batteries (LMBs) with high‐voltage nickel‐rich cathodes show great potential as energy storage devices due to their exceptional capacity and power density. However, the detrimental parasitic side reactions at the cathode electrolyte interface result in rapid capacity decay. Herein, a polymerizable electrolyte additive, pyrrole‐1‐propionic acid (PA), which can be in situ electrochemically polymerized on the cathode surface and involved in forming cathode electrolyte interphase (CEI) film during cycling is proposed. The formed CEI film prevents the formation of microcracks in LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) secondary particles and mitigates parasitic reactions. Additionally, the COO − anions of PA promote the acceleration of Li + transport from cathode particles and increase charging rates. The Li||NCM811 batteries with PA in the electrolyte exhibit a high capacity retention of 83.83% after 200 cycles at 4.3 V, and maintain 80.88% capacity after 150 cycles at 4.6 V. This work provides an effective strategy for enhancing interface stability of high‐voltage nickel‐rich cathodes by forming stable CEI film.