In situ construction of ether-based composite electrolyte with stable electrode interphase for high-performance solid state lithium metal battery

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Ether-based polymer electrolyte shows promising potential for application in solid-state lithium batteries owing to its cost-effectiveness, excellent flexibility, and above all, remarkable stability to lithium metal anode. However, it still suffers from challenges related to low ionic conductivity and inferior oxidation resistance. Herein, an ether-based gel composite electrolyte containing Li6.5La3Zr1.5Ta0.5O12 (LLZTO) ceramics (LL-GCE) is fabricated via an in-situ polymerization method which can guarantee good interface contact with electrodes. The ceramics not only activate the interaction between polymers and lithium salts, resulting in significantly enhanced ionic conductivity (7.9 × 10−4 S cm−1), but also collaborate with poly(1,3-dioxolane) (PDOL) to construct favorable anion-rich solvation configurations, which effectively restrict the anion migration with Li+ transference number significantly increased to 0.83. Furthermore, the regulated solvation structures can passivate the electrode surface with a high content of robust LiF components formed on the electrolyte/electrode interphase. Consequently, the composite electrolyte demonstrates excellent abilities to inhibit Li dendrite growth and match with high-voltage cathodes. For instance, the LiFePO4||Li cell using such electrolyte conveys a capacity of 135.4mAh/g and the capacity retention is 99.3 % after 250 cycles at 1C. The LiCoO2||Li full cell also shows excellent cycling performance. This work provides an effective strategy to modify ether-based polymer electrolytes and can boost their development in high-performance solid state lithium metal batteries.