A Flexible and Self-Healable Gelled Polymer Electrolyte Based on a Dynamically Cross-Linked PVA Ionogel for High-Performance Supercapacitors

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.

Phase-Transitional Ionogel-Based Supercapacitors for a Selective Operation

“…The SC OM exhibited an energy density of 7.77 Wh kg –1 at a power density of 4000 W kg –1 . The energy density and power density in this work are comparable to the performance of the previously reported carbon electrode and IL such as [Emim] + [OAc] − , [C 4 mim] + [OAc] − , [Emim] + [Cl] − , [EMIH] + [SO 4 ] − , [Pyr 14 ] + [Br] − , and [EMIM] + [BF 4 ] − based SCs (Figure d). The long-term cyclic stability of SC OM was also examined using a cyclic charge–discharge system at a current density of 0.5 A s –1 , as shown in Figure e.…”

Use of an [EMIM][OAc]/GVL-based organic electrolyte solvent to engineer chitosan into a nanocomposite organic ionogel electrolyte for flexible supercapacitors

“…In this regard, flexible supercapacitors are of note due to their excellent features including fast charge-discharge ability, long cycle life and high specific capacitance, and they are widely used in various fields, including consumer electronics, emergency power supply, and electric vehicles. [1][2][3][4][5] The electrolyte is one of the important components in a supercapacitor, directly affecting its electrochemical performance and safety. Particularly, with the increasing use of flexible supercapacitors, traditional liquid electrolytes usually suffer from some limitations that would restrict their practical applications, such as corrosion, difficulties in integration and the possibility of liquid leakage.…”

Plasticizing effect of 1‐butyl‐3‐methylimidazolium bromide content on poly(vinyl alcohol)

“…Wu et al 12 . prepared a dynamic diol borate ester‐crosslinked PVA ionogel electrolyte for smart double‐layer capacitors by adding boric acid and an IL, 1‐ethyl‐3‐methylimidazolium chloride (EmimCl).…”

“…), inorganic salts (MgCl 2 •6H 2 O, 9 AlCl 3 •6H 2 O, 10 MnCl 2 4H 2 O, 11 etc.) and ionic liquids (ILs; imidazolium-and pyridinium-based ILs, [12][13][14] etc.) as plasticizers have a good plasticizing effect on PVA.…”

“…[17][18][19] More importantly, ILs have been regarded as ideal plasticizers for polymers to realize their thermal processability, because they can overcome the shortcomings of traditional plasticizers. [20][21][22] Wu et al 12 prepared a dynamic diol borate ester-crosslinked PVA ionogel electrolyte for smart double-layer capacitors by adding boric acid and an IL, 1-ethyl-3-methylimidazolium chloride (EmimCl). It was found that the ionogel showed an amorphous nature with good flexibility, excellent self-healing efficiency and high ionic conductivity.…”