Internal in situ gel polymer electrolytes for high-performance quasi-solid-state lithium ion batteries

The performance of solid-state lithium ion battery mainly depends on the performance of the electrolyte and the interface between the electrolyte and the electrodes. Improving the interface contact between the electrolyte and the electrodes is vital for development of solid-state battery. In this work, the gel polymer electrolytes are prepared by thermal initiation and used as quasi-solid-state electrolytes in the LiFePO 4 /Li battery. In order to enhance the interface properties between the electrolyte and the electrodes, we adopt in situ polymerization strategy to form electrolyte in the inner of the battery. The scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and electrochemical impedance spectroscopy (EIS) are used to characterize the physico-chemical and electrochemical performance of gel polymer electrolytes. The final results show that the strategy of in situ polymerization of electrolyte in the inner of the battery can significantly improve the contact between the electrodes and electrolyte. The as-prepared quasi-solid-state battery shows lower interface resistance and significantly improved cycle performance. Therefore, the strategy of in situ polymerization of electrolyte in the inner of the battery provides a useful idea for solving the interface problem of quasi-solid-state batteries.