Design of highly stretchable deep eutectic solvent‐based ionic gel electrolyte with high ionic conductivity by the addition of zwitterion ion dissociators for flexible supercapacitor

Abstract

Nonvolatile deep eutectic solvent (DES) electrolytes with good electrochemical stability have recently emerged as promising electrolytes for energy storage devices. In this report, for the first time a polymerized zwitterionic molecule was introduced and a series of hybrid cross‐linked zwitterion‐containing copolymer DES gels are synthesized via UV initiated free‐radical copolymerization of acrylic acid (AA), sulfobetaine vinylimidazole (VIPS) and poly(ethylene glycol) diacrylate (PEGDA) monomers, in situ within DES, which is prepared from 1:2 M ratio of choline chloride and ethylene glycol. Systematically varying the AA:VIPS molar ratio and copolymer contents within the copolymer network enables one to widely tune the mechanical properties and ionic conductivity of the poly(AA‐co‐VIPS) DES gels. The tensile strength of P(AA‐co‐VIPS) DES gels significantly increased from 28 kPa to 176 kPa with fracture strain from 720% to 1370%, while the ionic conductivity of copolymer DES gels remains high from 2.7 to 4.1 mS cm−1 with the increase of copolymer content from 25 wt % to 45 wt%. A copolymer DES gel not only enables a supercapacitor deliver high capacitance of 71.52 F g−1 at 0.5 A g−1, and retains ∼97% of its capacitance after 2000 cycles, but also achieves outstanding capacitive performance over wide temperature range.

Deep Eutectic Solvents for Boosting Electrochemical Energy Storage and Conversion: A Review and Perspective

“…As a consequence, green, safe, and low-cost DES electrolytes are being intensively investigated for safety-and energy-enhancing supercapacitors. [88][89][90][91][92][93][94][95][96] Besides, DES electrolytes can afford the operation of supercapacitors at high temperatures, which is desired for some specific applications (e.g., military and aerospace). For example, Zaidi et al developed a new DES electrolyte based on sodium nitrate and NMAc for carbonbased supercapacitors at 80 °C.…”

Autonomous Self-Healing of Highly Stretchable Supercapacitors at All Climates

“…Compared with previously reported stretchable conductors that can work at extreme temperatures, the conductivity of the AACP gel was increased by 4 orders of magnitude (Figure i). − It was noteworthy that most of these reported conductors were stretchable at harsh temperature but healable only at room temperature. Herein, the intrinsically highly conductive cellular AgNW/Ag-CNT skeleton with densely assembled wall-like structure favored the recovery of conductive path within fractured parts once the broken interfaces were rapidly healed under a large number of hydrogen bonds in EG/H 2 O binary system as well as between the solvent molecules and PAM chains after the contact (Figure k­(i, ii)).…”

Tough and Ultrastretchable Liquid‐Free Ion Conductor Strengthened by Deep Eutectic Solvent Hydrolyzed Cellulose Microfibers

“…Overall, PDES/CMFs ICs achieved both superb stretchability and excellent tensile strength, compared to previously reported DES based gels and elastomers as summarized in Figure 1i. [ 22,24,28,44–51 ]…”

“…Overall, PDES/CMFs ICs achieved both superb stretchability and excellent tensile strength, compared to previously reported DES based gels and elastomers as summarized in Figure 1i. [22,24,28,[44][45][46][47][48][49][50][51] We speculated that the enhanced mechanical properties of PDES/CMFs ICs were ascribed to the load transfer mechanism. [52][53][54][55][56] As shown in Figure 2, in the initial state, the CMFs were uniformly and randomly distributed in the PAA network.…”