The Manipulation of Ring‐Open Polymerization Process to Boost the Electrochemical Performance for Solid‐State Lithium Metal Batteries

Abstract Solid‐state polyether electrolytes formed by in‐situ ring‐opening polymerization (ROP) of 1,3‐dioxolane (DOL) have attracted great attention due to their high lithium‐ion conductivity, and good interface compatibility. However, DOL ring‐opening polymerization is difficult to control, resulting in the formation of poly(1,3‐dioxolane) (PDOL) with high molecular weight and high crystallinity, which hinder Li + diffusion and deteriorate the interfacial contact. Herein, trimethylsilyl isocyanate (IPTS) was introduced into DOL ring‐opening system as a moisture eliminating agent to weaken the Li salt‐based initiating system and regulate the polymerization process. Based on this, the resultant PDOL electrolytes with 3 wt.% IPTS exhibit ionic conductivity of 2.8×10 −4 S cm −1 , a high Li + transference number (0.68) and excellent stability with Li anode. The Li|PDOL‐3 %IPTS|Li battery exhibits a stable cycling performance for more than 1100 h under 0.5 mA cm −2 and 0.5 mAh cm −2 . Furthermore, the LiFePO 4 |PDOL‐3 %IPTS|Li cell shows a capacity retention rate of 89.2 % after 200 cycles (25 °C, 1 °C) and 94.5 % (60 °C, 1 °C) after 500 cycles, which is much higher than that of PDOL (6.6 %) after 70 cycles (25 °C, 1 °C). This work provides guidance for the manipulation of ROP process further to enhance the performance of solid‐state lithium metal batteries.