Li2O-Integrated Electrodes Enabling Enhanced Adsorption/Defluorination Kinetics Toward LiF-Rich Interphase for High-Performance Lithium Metal Batteries

Abstract

Regulating interfacial chemistry at lithium (Li) anodes is vital for constructing robust solid-electrolyte interphase (SEI) and achieving reliable Li metal batteries (LMBs). Herein, an electrode-based strategy is proposed to regulate adsorption/defluorination kinetics of fluorinated electrolyte species by incorporating mechanochemically generated Li₂O nanoparticles into the Li/Li₂₂Sn₅ composite electrode, thereby constructing a LiF-rich SEI. This approach fundamentally differs from conventional methods that rely on concentrated salts or complex electrolyte formulations. Spectroscopic characterizations combined with density functional theory simulations confirm that the integrated-Li₂O nanoparticles strongly adsorb FEC and PF₆^– anions and promote their spontaneous defluorination, facilitating the preferential formation of LiF within the SEI. This inorganic-rich interphase homogenizes Li deposition and mitigates electrolyte corrosion even at 60 °C. Consequently, the composite electrode delivers a high average Coulombic efficiency of 99.0% over 50 plating/stripping cycles in carbonate electrolyte at 1 mA cm⁻² and 1 mAh cm⁻². Paired with LiCoO₂ cathodes, it achieves outstanding cyclability with 87.0% capacity-retention at a low negative-to-positive ratio of 2:1 and 84.8% capacity-retention under lean-electrolyte conditions (20 µL) after 200 cycles over a wide voltage range of 2.8–4.5 V. This work highlights regulating adsorption/defluorination kinetics as an effective route to engineer LiF-rich SEI and enable high-performance LMBs.