Self-Healing and Recyclable Polymer Electrolyte Enabled with Boronic Ester Transesterification for Stabilizing Ion Deposition

Abstract

Damage to solid polymer electrolytes can lead to mechanical degradation, short circuits, or functional failures. Therefore, introducing a self-healing function to solid polymer electrolytes is an ideal strategy to improve the safety and reliability of electrolyte systems. Herein, dynamic boronic ester-based self-healing polymer electrolytes (DB-SHPEs) with excellent mechanical properties and interfacial stability are developed via a thermally initiated ring-opening reaction between thiol and epoxy groups. The DB-SHPEs containing boronic ester bonds can not only alter the topologies via boronic ester transesterification and exhibit good self-healing capability but also enable homogeneous deposition of Li ions on the Li metal through the Lewis acid–base interactions between boron atoms and salt anions. Furthermore, the boronic ester bonds can endow the DB-SHPE with reprocessability and recyclability taking advantage of associative transesterification reaction. More significantly, the Li/DB-SHPE/Li symmetric cells exhibit a stable voltage plateau after cycling for 1200 h and the LiFePO₄/DB-SHPE/Li batteries present excellent cycling performance, suggesting that high-performance self-healing polymer electrolytes with multiple functions are promising materials for the next-generation lithium metal batteries.