Minimized Li-Ion Coordination Diluent Differentiating Dual-Anion-Derived Solid Electrolyte Interphase Towards Long-Life Lithium Metal Batteries

Rechargeable lithium (Li) metal batteries face persistent challenges in maintaining stable electrochemical performance, attributed to Li metal's high reactivity and the SEI's instability. Electrolyte composition plays a crucial role in reducing parasitic reactions at the Li metal anode and establishing a stable SEI. In this study, a novel fluorinated cyclic ether was synthesized, exhibiting enhanced electrochemical stability and minimizing Li-ion coordination capability. Its role in manipulating SEI formation was demonstrated, showcasing a bilayer SEI with a Li2O-rich inner layer and a LiF-rich outer layer, ensuring impressive stability and reversibility of Li metal anodes. The developed electrolyte showed significant enhancement in calendar life and cycling stability of Li (50 µm)||NMC811 (4 mAh/cm2) cells, leading to prototype pouch cells with a remarkable cycling stability of 80% capacity for up to 470 cycles, achieving 410 Wh/kg. This work highlights the potential of electrolyte engineering in advancing next-generation Li metal batteries towards high-energy-density applications.