Self-Healing Polymer Electrolyte Based on Boronic Ester Bonds with Hydroxyl Groups Synergistically for Lithium-Metal Batteries

Dynamic covalent boronic ester polymer networks have received extensive attention as self-healing materials, and they can be applied in all-solid polymer electrolytes. Herein, some classes of solid-state polymer electrolytes with self-healing ability were developed by incorporating dynamic boronic ester structure into a comb-like polyethylene glycol polymer network. Due to the dynamic transesterification reactions of boronic ester bonds, the borate ester-containing cross-linked polymer electrolyte with free hydroxyl (3OHPBASPE-2) exhibits the ability to dynamically alter its network topology, giving 3OHPBASPE-2 an excellent self-healing property and enhanced ductility. Benefit from the comb-like polyethylene glycol segments within the polymer network, along with the robust interactions between boron element and TFSI –, the 3OHPBASPE-2 displays delightful ionic conductivity of 3.06 × 10 –4 S cm –2 at 65 °C and outstanding lithium-ion transference number of 0.65 at room temperature. Simultaneously, the samples recovered their original ionic conductivity after self-healing. Owing to the generation of a robust LiF-rich solid electrolyte interphase, the 3OHPBASPE-2 can also suppress lithium dendrite growth effectively. The LFP|3OHPBASPE-2|Li cell demonstrates an outstanding initial discharge capacity of 163.5 mA h·g –1, remarkable cycling stability, and a high Coulombic efficiency of 94.5% at a current rate of 0.1 C. Significantly, the 3OHPBASPE-2 polymer electrolyte can repair the damage within the LFP|3OHPBASPE-2|Li pouch cell, enabling the illumination of light-emitting diodes even under the harsh conditions. This capability notably bolsters the reliability and safety of batteries, thereby broadening the potential applications of solid-state electrolytes in the realm of emerging flexible energy storage devices.