Fabrication of Gelatin-Derived Gel Electrolyte Using Deep Eutectic Solvents through In Situ Derivatization and Crosslinking Strategy for Supercapacitors and Flexible Sensors

Abstract

The facile fabrication of gel polymer electrolytes is crucial to the development of flexible electronics, and the use of natural polymers as sources has obtained great attention due to their abundant, low-cost, biodegradable, easy modification, and biocompatible features. In this article, a facile fabrication protocol to engineer gelatin into gel electrolytes was developed by taking the advantages of both deep eutectic solvent (DES) (including its good solubility to gelatin and satisfactory electrochemical properties) and rich active functional groups of gelatin, through in situ derivatization and crosslinking strategy. A double-crosslinked DES gel electrolyte was prepared with the dissolution of gelatin in choline chloride and alcohol-based DES and a further crosslinking with Fe 3+ ions. The obtained DES gel presented outstanding mechanical properties, excellent ionic conductivity (up to 10 1 −10 2 mS/cm), a wide operating temperature range (−40 to 80 °C), satisfactory self-healing property, and good degradability. Moreover, the obtained DES gel electrolyte was successfully applied to supercapacitors and flexible sensors, showing excellent electrochemical performance and strain-response properties. In a word, our study provides a facile protocol to engineer gelatin into gel electrolytes by using deep eutectic solvent, showing significant insights into the design and preparation of sustainable gel polymer electrolytes and having great application potential in next-generation highperformance flexible electronics.

One‐step preparation of highly conductive eutectogel for a flexible strain sensor

“…These values represent a significant increase, which is one order of magnitude higher than the ionic conductivity of pure DES. In addition, the performance of the M‐DES eutectogel surpasses that of other representative conductive eutectogels reported in the literature, 21,30–39 as illustrated in Figure 1d, which underscores the notable improvement in ionic conductivity. This significant enhancement is attributed to the effective ion transport facilitated by the quaternary ammonium salt structures, which have been shown to create an effective pathway for ion migration 40–42 .…”

Copolymers of Gelatin-graft-poly(3-hexylthiophene) for Transient Electronics

“…Gelatin is a valuable water-soluble biopolymer, which is derived from the controlled hydrolysis of collagen . Gelatin was chosen as the backbone polymer because of its availability, biocompatibility, biodegradability, and abundance of functional groups . We hypothesized that, during enzymatic degradation of Gel- g -P3HT, the biodegradable gelatin chain will break down at the peptide bonds of gelatin (while the covalent amine bonds between short gelatin chains and P3HT remain unaffected), resulting in amphiphilic degradation products.…”

“…The carboxylic acid groups on P3HT-COOH allowed for subsequent grafting of P3HT-COOH onto the amine groups of gelatin utilizing EDC/NHS chemistry to give the grafted copolymer Gel- g -P3HT (Figure ). Gelatin is a valuable water-soluble biopolymer, which is derived from the controlled hydrolysis of collagen . Gelatin was chosen as the backbone polymer because of its availability, biocompatibility, biodegradability, and abundance of functional groups .…”

Polymer ionogels and their application in flexible ionic devices

“…The presence of this 3D ion channel network within the polymer matrix facilitates ions to directionally migrate and redistribute under external electric fields. The combination of solid‐state polymer networks and ILs/DESs offers many possible properties, including high ionic conductivity, 19–21 nonvolatility, high thermal and electrochemical stability, excellent mechanical properties, 22–24 transparency, and self‐healing capabilities 25 . Compared to conventional ionic hydrogels, PIGs address the issue of water evaporation and exhibit an expanded operating temperature range (from below 0 °C to above 100 °C).…”