Preparation of thin-film electrolyte from chitosan-containing ionic liquid for application to electric double-layer capacitors

• Published in: International journal of biological macromolecules 2019-03, Vol.124, p.1274-1280
• Main Authors: Kotatha, Ditpon, Torii, Yoshiki, Shinomiya, Keito, Ogino, Mayuko, Uchida, Satoshi, Ishikawa, Masashi, Furuike, Tetsuya, Tamura, Hiroshi
• Format: Article
• Language: English
• Subjects: Chitosan; Electric double-layer capacitors; Ionic liquid; Solid electrolyte; Thin-film electrolyte
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2018.12.006

A novel thin-film electrolyte (TFE) based on chitosan (CS) with 1‑ethyl‑3‑methylimidazolium tetrafluoroborate (EMImBF4) was prepared by a new procedure for use as a solid electrolyte in electric double-layer capacitors (EDLCs). In this system, EMImBF4 plays important roles as both a dissolving solution and a charge carrier for EDLC application. By analyzing and characterizing the obtained products, the CS-TFEs showed a surface without CS/EMImBF4 phase separation and with high thermal stability and good tensile properties. The electrochemical properties were measured as the charge–discharge performance, the discharge capacitance, and alternating-current impedance. A test cell with CS-TFE with a calculated dry thin-film content of 80 wt% EMImBF4 showed a comparable IR drop and higher discharge capacitance than a liquid-phase EMImBF4 system and also showed low electrode/electrolyte interfacial resistance. Consequently, this novel CS-TFE is suitable for high-performance EDLCs and improves the safety of such devices. •A new method for preparing a chitosan thin-film electrolyte (CS-TFE).•1‑ethyl‑3‑methylimidazolium tetrafluoroborate (EMImBF4) used for this preparation.•EMImBF4 is a solvent and charge carrier for electric double-layer capacitors (EDLC).•The obtained CS-TFEs have a homogeneous surface, are tensile, and thermally stable.•The obtained CS-TFE can have high-performance and be safety-oriented EDLCs.