A novel strategy to improve the electrochemical properties of in-situ polymerized 1,3-dioxolane electrolyte in lithium metal batteries

Abstract

The application of solid-state electrolytes (SSEs) is anticipated to enhance the safety performance of lithium metal batteries (LMBs). However, the progress of SSEs has been hindered by the unstable electrode–electrolyte interfaces (EEIs). In this study, in-situ polymerization of 1,3-dioxolane (DOL) is employed for the preparation of SSEs, with the addition of tributyl borate (TBB) to establish stable EEIs, particularly under high-voltage conditions. On one hand, the addition of TBB promotes the dissociation of lithium salts and increases the concentration of free Li+, resulting in an increase in room temperature ionic conductivity to 1.13 × 10−4 S cm−1 and an improvement in the Li+ transference number to 0.69 for the prepared poly-DOL electrolytes (PDE-TBB). Benefiting from the enhanced Li+ transport, the Li/PDE-TBB/Li symmetric cell exhibits a cycle life exceeding 1,000 h with a low polarization voltage as low as 12 mV, and the Li/PDE-TBB/LiFePO4 cell demonstrates exceptional cyclic stability over 800 cycles at 1C, with a coulombic efficiency exceeding 99.8 % and a capacity retention of 89.6 %. On the other hand, PDE-TBB exhibits improved stability under high-voltage conditions and the capacity to establish robust boron-rich cathode electrolyte interphase (CEI) on the LiNi0.8Co0.1Mn0.1O2 (NCM811) surface, thereby enhancing the structural stability of cathode materials and ensuring exceptional cycling performance of Li/PDE-TBB/NCM811cell. This work presents a promising strategy for developing novel ether-based SSEs suitable for high-voltage lithium metal batteries.