Highly conductive self-healing polymer electrolytes based on synergetic dynamic bonds for highly safe lithium metal batteries

Abstract

Self-healing polymer electrolytes can improve the safety, reliability and cycle life of the batteries. Herein,we developed a self-healing polymer electrolyte (IBshPE) with high ionic conductivity and excellent self-healing property. IBshPE cross-linked by synergetic dynamic imine bond and boroxine bond was prepared via the reaction of 2-formylphenylboronic acid and poly(ethylene glycol) diamine. In IBshPE, boroxine bonds with B-N coordination and imine bonds can synchronously undergo fast bond exchange reactions, enabling rapid self-healing of IBshPE. IBshPE shows high self-healing efficiency of 97% within 4 h. The healed IBshPE has nearly the same mechanical property and ionic conductivity as the original IBshPE. IBshPE exhibits the highest ionic conductivity (5.08 × 10−3 S cm−1 at 30 °C) among the reported self-healing polymer electrolytes. IBshPE facilitates the construction of robust LiF-rich SEI and efficiently inhibits dendrite growth. LiFePO4/Li cells with IBshPE exhibits excellent cycle performance (capacity retention of 98.6% after 80 cycles) and good rate capability (specific capacity of 130.5 mAh g−1 at 2C rate). More importantly, IBshPE is capable of self-repairing damage in the LiFePO4/Li cells and restoring the performance of the cells, thus effectively enhancing the reliability and safety of the battery.