In-Situ Formation of Polymer Electrolytes Using a Dicationic Imidazolium Cross-linker for High-Performance Lithium Ion Batteries

Improving the electrochemical performance of polymer electrolytes in lithium ion batteries has been intensively studied. Herein, we adopted an in situ solventless polymerization strategy to fabricate PEG-based electrolytes cross-linked by a dicationic imidazolium compound directly onto the lithium anode, providing a direct, effective, and versatile pathway for the preparation of electrolytes. The electrolytes exhibit high thermal stability, a wide electrochemical window, an ionic conductivity higher than 10−4 S cm−1 and an outstanding deformation stability without cracking at a 60% compressive strain. A conformal attachment at the electrolyte/electrode interface and a superior charge–discharge capacity as well as a long cycle life at 25 °C (0.2C rate, 93.8% after 150 cycles) and 60 °C (0.5C rate, 94.6% after 100 cycles) can be achieved in the equipped Li/LiFePO4 cell by forming electrolytes on lithium metal directly, which represents a promising approach for next-generation lithium ion battery technologies.