Optimization of the Properties of Photocured Hydrogels for Use in Electrochemical Capacitors.

Piotr Gajewski,Aneta Lewandowska,Katarzyna Szcześniak,Grzegorz Przesławski,Agnieszka Marcinkowska

doi:10.3390/polym13203495

Piotr Gajewski, Aneta Lewandowska + Show 3 more

Open Access

https://doi.org/10.3390/polym13203495

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Journal: Polymers	Publication Date: Oct 12, 2021
Citations: 4	License type: CC BY 4.0

Affiliation: Poznań University of Technology

Abstract

In this work, hydrogel polymer electrolytes (HPEs) were obtained by the photopolymerization of a mixture of two monomers: Exothane 8 (Ex8) and 2-hydroxyethylmethacrylate acid phosphate (HEMA-P) in an organic solvent N-methyl-2-pyrrolidone (NMP), which was replaced after polymerization with water, and then with the electrolyte. The ratio of monomers as well as the concentration of NMP was changed in the composition to study its influence on the properties of the HPE: conductivity (electrochemical impedance spectroscopy, EIS) and mechanical properties (puncture resistance). Properties were optimized using a mathematical model to obtain a hydrogel with both good mechanical and conductive properties. To the best of our knowledge, it is the first publication that demonstrates the application of optimization methods for the preparation of HPE. Then, the hydrogel with optimal properties was tested as a separator in a two-electrode symmetric AC/AC pouch-cell. The cells were investigated by cyclic voltammetry galvanostatic charge/discharge with potential limitation and EIS. Good mechanical properties of HPE allowed for obtaining samples of smaller thickness while maintaining very good dimensional stability. Thus, the electrochemical capacitor (EC) resistance was reduced and their electrochemical properties improved. Moreover, photopolymerization kinetics in the solvent and in bulk by photo-DSC (differential scanning calorimetry) were performed. The great impact on the polymerization of HEMA-P and its mixtures (with Ex8 and NMP) have strong intermolecular interactions between reagents molecules (i.e., hydrogen bonds).

Highlights

The development of civilization and the related increase in the demand for electricity forces us to look for new solutions in the field of energy storage devices [1,2,3]
Application of the hydrogel polymer electrolyte (HPE) in electrochemical capacitors requires preparing hydrogel polymer electrolytes (HPEs) characterized by good mechanical properties as well as good conductivity, at the same time
We demonstrated that proper choice of photocurable mixture composition allowed us to regulate both of these properties of HPE

Summary

Introduction

The development of civilization and the related increase in the demand for electricity forces us to look for new solutions in the field of energy storage devices [1,2,3]. Electrochemical capacitors (ECs), known as supercapacitors, are one of the types of equipment that has been given special attention. Thanks to their specific properties, ECs can be applied everywhere where many fast charge/discharge cycles or peak power generation are required. One of the key parts of EC is the electrolyte. It can have a large impact on EC properties such as electrochemical stability window, capacity, thermal stability, energy, and power density, life cycle, etc. It can have a large impact on EC properties such as electrochemical stability window, capacity, thermal stability, energy, and power density, life cycle, etc. [2,3]

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