Evaluation of Polymer Gel Electrolytes for Use in MnO2 Symmetric Flexible Electrochemical Supercapacitors

Yu-Hao Lin; Wan-Tien Huang; Yi-Ting Huang; Yi-Ni Jhang; Tsung-Ting Shih; Murat Yılmaz; Ming-Jay Deng

doi:10.3390/polym15163438

Evaluation of Polymer Gel Electrolytes for Use in MnO₂ Symmetric Flexible Electrochemical Supercapacitors

Polymers (Basel). 2023 Aug 17;15(16):3438. doi: 10.3390/polym15163438.

Authors

Yu-Hao Lin¹, Wan-Tien Huang², Yi-Ting Huang², Yi-Ni Jhang², Tsung-Ting Shih³, Murat Yılmaz⁴, Ming-Jay Deng²

Affiliations

¹ Department of Environmental Engineering, National Chung Hsing University, Taichung 40227, Taiwan.
² Department of Applied Chemistry, Providence University, Taichung 43301, Taiwan.
³ Department of Chemistry, Fu Jen Catholic University, New Taipei City 24205, Taiwan.
⁴ Department of Chemical Engineering, Faculty of Engineering, Osmaniye Korkut Ata University, Osmaniye 80000, Turkey.

Abstract

Flexible electrochemical supercapacitors (FESCs) are emerging as innovative energy storage systems, characterized by their stable performance, long cycle life, and portability/foldability. Crucial components of FESCs, such as electrodes and efficient electrolytes, have become the focus of extensive research. Herein, we examine deep eutectic solvent (DES)-based polymer gel systems for their cost-effective accessibility, simple synthesis, excellent biocompatibility, and exceptional thermal and electrochemical stability. We used a mixture a DES, LiClO₄-2-Oxazolidinone as the electroactive species, and a polymer, either polyvinyl alcohol (PVA) or polyacrylamide (PAAM) as a redox additive/plasticizer. This combination facilitates a unique ion-transport process, enhancing the overall electrochemical performance of the polymer gel electrolyte. We manufactured and used LiClO₄-2-Oxazolidinone (LO), polyvinyl alcohol-LiClO₄-2-Oxazolidinone (PVA-LO), and polyacrylamide-LiClO₄-2-Oxazolidinone (PAAM-LO) electrolytes to synthesize an MnO₂ symmetric FESC. To evaluate their performance, we analyzed the MnO₂ symmetric FESC using various electrolytes with cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The FESC featuring the PVA-LO electrolyte demonstrated superior electrochemical and mechanical performances. This solid-state MnO₂ symmetric FESC exhibited a specific capacitance of 121.6 F/g within a potential window of 2.4 V. Due to the excellent ionic conductivity and the wide electrochemical operating voltage range of the PVA-LO electrolyte, a high energy density of 97.3 Wh/kg at 1200 W/kg, and a long-lasting energy storage system (89.7% capacitance retention after 5000 cycles of GCD at 2 A/g) are feasibly achieved. For practical applications, we employed the MnO₂ symmetric FESCs with the PVA-LO electrolyte to power a digital watch and a light-emitting diode, further demonstrating their real-world utility.

Keywords: Mn oxide; deep eutectic solvent; electrochemical supercapacitor; flexible; polymer gel electrolyte.

Grants and funding

This research was supported by National Science and Technology Council (Taiwan) (NSTC 110-2221-E-126-006-MY3, 111-2221-E-110-001, and 112-2221-E-110-002).