Composite electrolytes have been regarded as the most prospective electrolytes for commercial application because they acquire the advantages of both polymer and inorganic electrolytes, commonly exhibiting appreciated flexibility and suitable ionic conductivity. Nevertheless, the conventional solution-casting method with toxic solvent and poor interfacial contact still hamper their commercialization process. Moreover, electrolytes with higher ionic conductivity and transference number are urgently needed for satisfying fast-charging batteries. Herein, a novel composite electrolyte (LZEC) reinforced by mechanically robust LLZTO nanoparticles and flexible cellulose mesh was fabricated by a simple and advanced in situ thermal polymerization method, with adding of highly ion-conductive liquid plasticizer. Consequently, the rationally designed LZEC composite electrolyte exhibits superior flexibility and remarkable electrochemical properties in the form of high ionic conductivity, wide electrochemical stability window, and high Li+ transference number. Importantly, the in situ synthesis method is expected to help construct an enhanced electrolyte/electrode interface inside the battery, and the LZEC composite electrolyte is capable of suppressing Li dendrite growth effectively, as evidenced by the prolonged stable cycling of the Li/Li symmetric cell. Therefore, the LFP/LZEC/Li full cell exhibits superior rate performance and long cyclic life. These attractive properties make LZEC a potential composite electrolyte for boosting the practical application of safe and long-life Li metal batteries.
Keywords: LLZTO; composite electrolyte; flexibility; solid-state Li batteries; thermal polymerization.