Dynamic Anode/Cathode-Electrolyte Interface Induced through Polymer Evolution for Durable Lithium Metal Batteries

Fine-tuning the solid-electrolyte interface (SEI) on the Li anode has been widely developed to break through the cyclability bottleneck of Li metal batteries (LMBs). Meanwhile, the cycling behavior of LMBs is also dependent on cathode stability, and hence, it is promising to develop strategies that simultaneously constrain Li dendrite growth and cathode particle distortion. Herein, through copolymerization of maleic anhydride (MA) and hexafluorobutyl acrylate (HFA) monomers, an artificial interface (noted as MAF) is constructed on the Li anode. Such an MAF layer establishes hybrid SEI components consisting of an inorganic-rich interior and a polymer exterior. Its bifunctional contributions on the Li anode and the LiFePO₄ (LFP) or LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathode are validated by virtue of its dynamic polymer evolution upon LMB cycling. Besides providing lithophilic sites for even Li⁺ plating, the fluorinated oligomers within the MAF exterior further evolve under an ethylene carbonate (EC)-based electrolyte, inducing dynamic maturation of the LiF-rich cathode-electrolyte interface (CEI). As a result, Li||Li symmetric cells perform for over 900 h of cycling at 1 mA cm^-2, while Li||LFP and Li||NCM811 cells maintain capacity retentions of 90.2% after 1500 cycles and 80.6% after 350 cycles at their respective 1 C rate.