3D printing flexible supercapacitors based on crosslinked poly (acrylic acid‐co‐vinylimidazole)

Abstract

Supercapacitors are an attractive technology for energy storage applications as they allow for fast charging of devices. The fabrication of flexible supercapacitors by additive manufacturing is a promising approach to produce energy storage components for applications where material flexibility and complex geometries are desirable. In this work, digital light projection (DLP) additive manufacturing is used to fabricate polymer electrolytes for flexible supercapacitors based on crosslinked poly(acrylic acid‐co‐vinylimidazole) (PAAVim). Ion gels are prepared through equilibration with 4M lithium chloride (LiCl) in ethylene glycol, deionized (DI) water and ethylene glycol/DI water mixtures. Flexibility and stretchability varied depending on the equilibration solvent with prepared PAAVim/LiCl polymer electrolytes exhibiting up to ˜700% elongation at break. Subsequent flexible supercapacitors fabricated by sandwiching the ion gel between carbon cloth electrodes delivered 60 F/g specific capacitance at the scan rate of 0.2 A/g with an energy density of 8.3 Wh/kg and a power density of 99.8 W/kg. Overall, this work demonstrates the fabrication of flexible capacitors through DLP additive manufacturing, where the resulting material physical and electrochemical properties can be varied through control over the resin chemistry.

Current Trends and Promising Electrode Materials in Micro-Supercapacitor Printing

“…Polymer-based electrolytes can be divided into three groups: (a) solid-state electrolytes (e.g., based on Nafion [ 110 ], polyaryletherketone [ 111 ]); (b) polymer gel electrolytes, which are further divided into hydrogel electrolytes (water as the solvent), e.g., systems based on polyvinyl alcohol (PVA), polyacrylamide (PAM), biopolymers (chitosan, agarose) [ 109 ], and organogel electrolytes (organic solvent is used, e.g., systems based on poly(acrylic acid-co-vinylimidazole) in ethylene glycol [ 112 ] and poly(vinylidene fluoride-co-hexafluoropropylene) in acetone [ 113 ]); and (c) polymer-ionic liquid electrolyte, which are melts (melting point below 100 °C) of organic salts consisting of highly asymmetric anions and cations distributed in a polymer matrix [ 114 , 115 ]. When developing polymer-based electrolytes, it is necessary to consider not only the value of their ionic conductivity, but also the degree of ion selectivity.…”