All-Solid-State High-Voltage Supercapacitors Using an Ionic Plastic Crystal-Based Electrolyte

Masahiro Yoshizawa-Fujita,Satoshi Kubota,Shuichi Ishimoto

doi:10.3389/fenrg.2022.854090

Masahiro Yoshizawa-Fujita, Satoshi Kubota + Show 1 more

Open Access

https://doi.org/10.3389/fenrg.2022.854090

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Abstract

Recently, ionic plastic crystals (IPCs) have been actively investigated to develop all-solid-state rechargeable batteries, such as lithium-ion batteries. Herein, we report supercapacitors assembled with mesoporous carbon electrodes and an IPC electrolyte, N-ethyl-N-methylpyrrolidinium bis(fluorosulfonyl)amide ([C2mpyr][FSA]). [C2mpyr][FSA] with a 10 mol% lithium bis(fluorosulfonyl)amide (LiFSA) dopant was used as the solid electrolyte in the supercapacitors. The charge–discharge tests of the supercapacitors were performed at various C-rates in the voltage range of 0–2.5 V at 25°C. The capacitance of the cells was 12.3 Fg−1 at a lower C rate (1 C = 8.9 mA g−1). The capacitance retention of the supercapacitors was maintained at approximately 100% up to 20 C, which was comparable to that of the cells containing organic electrolyte solutions. The advantage of using solid electrolytes was the fabrication of bipolar cells using two pairs of mesoporous carbon electrodes and a [C2mpyr][FSA]/LiFSA composite. The charge–discharge tests of the bipolar cells were also performed in the voltage range of 0–5.0 V at 25°C. The capacitance of the bipolar cells was 6.4 Fg−1 at a lower C rate. The bipolar cells exhibited a typical charge–discharge profile for 1,000 cycles, confirming their stable cyclic performance. Thus, IPC electrolytes are interesting materials for developing all-solid-state high-voltage supercapacitors.

Highlights

An electrochemical capacitor, known as a supercapacitor, is a device that stores electric energy by forming an electric double layer at the electrode/electrolyte interface (Pandolfo and Hollenkamp, 2006;Simon and Gogotsi, 2008)
We showed that ionic plastic crystals (IPCs) based on pyrrolidinium cations and bis(fluorosulfonyl)amide (FSA)
When Dimethyl carbonate (DMC) was used as the solvent, many voids were observed in the pores of the electrode, even at low magnification in the scanning electron microscopy (SEM) image (Supplementary Figure S1)

Summary

Introduction

Known as a supercapacitor, is a device that stores electric energy by forming an electric double layer at the electrode/electrolyte interface (Pandolfo and Hollenkamp, 2006;Simon and Gogotsi, 2008). In this study, [C2mpyr] [FSA] doped with 10 mol% LiFSA was prepared as a solid electrolyte and further used with mesoporous carbon electrodes to fabricate all-solid-state supercapacitors. The carbon electrodes and a separator filled with the [C2mpyr][FSA]/LiFSA composite were assembled and dried in a vacuum at 120°C for 12 h.

Results

Conclusion