Working mechanisms for enhanced interface stability and electrochemical properties in dual-salt polymer electrolyte with in-situ electrolyte-cathode integration.

Solid polymer electrolytes (SPEs) have attracted much attention due to their excellent flexibility, strong interfacial adhesion and good processibility. However, the incompatibility at the electrode/electrolyte interface often results in increased impedance and rapid capacity attenuation. In this work, dual-salt composite solid electrolytes (CSEs) with an integrated electrolyte/cathode structure are prepared by in-situ ultraviolet (UV) photopolymerization. With the addition of the lithium difluoro(oxalato)borate (LiDFOB), a robust, stable and low-resistance solid-electrolyte interface (SEI) layer is established during electrochemical reduction, eventually improving the overall performance of all solid-state lithium batteries (ASSLBs). The Li//Li symmetric cells with RTS-TH-2% LiDFOB ASSLB exhibit stable cycling for over 2000 h at at 0.1 mA cm-2@0.1 mAh cm-2. LiFePO4//Li full cells deliver a high discharge capacity (155 mAh g-1 at 0.5 C) and cycling stability (with the retention rate of more than 90% at 0.5 C after 100 cycles) at 60 °C. This work provides a facile strategy to enhance electrodes compatibility with poly (ethylene glycol) acrylates (PEGAs)-based electrolytes.