Molecular Reactivity and Interface Stability Modification in In‐Situ Gel Electrolyte for High Performance Quasi‐Solid‐State Lithium Metal Batteries

Abstract

Quasi‐solid‐state lithium metal battery is a promising candidate for next generation high energy density and high safety power supply. Despite intensive efforts on electrolytes, uncontrolled interfacial reactions on lithium with electrolyte and patchy interfacial contacts still hinder its practical process. Herein, we bring in rationally designed F contained groups into polymer skeleton via in‐situ gelation for the first time to establish quasi‐solid‐state battery. This method achieves a capacity retention of 90% after 1000 cycles at 0.5C with LiFePO4 cathodes. The interface constructed by polymer skeleton and reaction with –CF3 lead to the predicted solid electrolyte interface species with high stability. Furthermore, we optimize molecular reactivity and interface stability with regulating F contained end groups in the polymer. Comparisons on different structures reveal that high performance solid stable lithium metal batteries rely on chemical modification as well as stable polymer skeleton, which is more critical to construct robust and steady SEI with uniform lithium deposition. New approach with functional groups regulation proposes a more stable cycling process with a capacity retention of 94.2% at 0.5C and 87.6% at 1C after 1000 cycles with LiFePO4 cathodes, providing new insights for the practical development of quasi‐solid‐state lithium metal battery.