A self-healing hydrogel derived flexible all-solid-state supercapacitors based on dynamic borate bonds

Flexible energy storage devices are susceptible to damage, which might result in safety issues. In this paper, a self-healing flexible P(AAPBA-co-P4-AC) gel electrolyte based on dynamic borate bond cross-linking strategy is reported. On the one hand, it is simple to process into complicated shapes or patterns, and on the other hand, it could rapidly return to its original state after stress damage. Even after ten times self-healing, the gel has the same mechanical properties as the non-damaged gel. Furthermore, this gel can also be applied in all-solid-state supercapacitors without the need of extra electrolytes. Because the gel has a large number of hydroxyl groups, it has a high affinity for the activated carbon electrode, and the supercapacitors can maintain 100% initial performance under various angles or strains. After ten thousand times cycles charge–discharge, the supercapacitors using the gel after twenty times self-healing process can retain 90% of its initial capacity, which is only 4% lower than the non-damaging supercapacitors, demonstrating high self-healing ability.