Trimethyl phosphate‐enhanced polyvinyl carbonate polymer electrolyte with improved interfacial stability for solid‐state lithium battery

Abstract The polyvinyl carbonate (PVC) polymer solid electrolyte can be in‐situ generated in the assembled lithium‐ion battery (LIBs); however, its rigid characteristic leads to uneven interface contact between electrolyte and electrodes. In this work, trimethyl phosphate (TMP) is introduced into the precursor solution for in‐situ generation of flexible PVC solid electrolyte to improve the interfacial contact of electrolyte and electrodes together with ionic conductivity. The PVC‐TMP electrolyte exhibits good interface compatibility with the lithium metal anode, and the lithium symmetric battery based on PVC‐TMP electrolyte shows no obvious polarization within 1000 h cycle. As a consequence, the initial interfacial resistance of battery greatly decreases from 278 Ω (LiFePO 4 (LFP)/PVC/Li) to 93 Ω (LFP/PVC‐TMP/Li) at 50 °C, leading to an improved cycling stability of the LFP/PVC‐TMP/Li battery. Such in‐situ preparation of solid electrolyte within the battery is demonstrated to be very significant for commercial application.