A Flexible and Self-Healable Gelled Polymer Electrolyte Based on a Dynamically Cross-Linked PVA Ionogel for High-Performance Supercapacitors
Jintian Wu, Gaojing Xia, Shangbo Li, Lupei Wang, Jianjun Ma
Abstract
Ionogels combine the virtues of polymers and ionic liquids (ILs) and have greater potential for supercapacitors (SCs) than hydrogels and organic gels. Undoubtedly, the self-healing ability of ionogels dramatically improves the reliability of related SCs. Herein, we reported a dynamic diol-borate ester-cross-linked polyvinyl alcohol (PVA) ionogel electrolyte for smart double-layer capacitors. The results indicated that 1-ethyl-3-methylimidazolium chloride (EmimCl) could form a strong interaction with the hydroxy groups on PVA, thereby depressing the crystallization efficiently. The resultant ionogel exhibited an amorphous nature with excellent ionic conductivity up to 2.43 × 10–3 S/cm, high flexibility, and 95% healing efficiency when the IL content was 90 vol %. It could be inferred from the fact that EmimCl acted not only as an ion provider to improve the ionic conductivity but also as a plasticizer to enhance the chain mobility and self-healing efficiency. Based on the unique properties of PVA-boric acid/EmimCl ionogels, a flexible and self-healable SC was assembled. The as-prepared SC delivered a specific capacitance of 90 F/g at 0.1 A/g and retained 98% capacitance after 3000 charge–discharge cycles at a current density of 2 A/g. More interestingly, it could tolerate physical bending and healing without significant performance deterioration. The present study provides a novel strategy to prepare self-healable ionogel electrolytes that can be applied to smart energy storage devices.