N-Propyl-N-Methylpyrrolidinium Difluoro(oxalato)borate as a Novel Electrolyte for High-Voltage Supercapacitor.

Weili Zhang,Peng Zhang,Shuo Liang,Fuming Zhang,Zhiqiang Shi

doi:10.3389/fchem.2019.00664

Abstract

Development of high voltage electrolyte is one of the effective ways to improve the performance of supercapacitor. The new ionic liquid N-propyl-N-methylpyrrolidinium difluoro(oxalato)borate (Py13DFOB) was designed and mixed with propylene carbonate (PC) as electrolyte for supercapacitor. The operating voltage of the new electrolyte system has been proven to be up to 3.0 V by a series of electrochemical techniques. Surprisingly, the new salt exhibits nearly symmetric capacitance contribution in the positive and negative electrodes, leading to a high capacitance value of 130 F g−1. The energy and power density of EDLCs using Py13DFOB in the PC electrolyte reach 39.06 Wh kg−1 (100 mA g−1) and 8.03 kW kg−1 (5,000 mA g−1), respectively, at the working voltage of 3.0 V, significantly exceeding the performance of commercial electrolyte tetraethylammonium tetrafluoroborate (TEABF4). The results indicate that Py13DFOB can be a promising electrolyte salt for supercapacitor.

Highlights

Supercapacitors (SCs), a kind of electrochemical energy storage device with high power density, long cycle life, and excellent reliability, has been widely used in many fields such as hybrid electric vehicle and high-power output equipment
Afterwards, we evaluated the performance of supercapacitors containing Py13DFOB/propylene carbonate (PC) electrolyte from the aspects of withstand voltage, cycle stability, energy density, power density, etc
The specific capacitance obtained from the discharge time of the galvanostatic charge/discharge tests (GCD) curves can reach a high value of 130 F/g at a current density of 100 mA g−1 and still maintain 96 F g−1 at 5,000 mA g−1 under a working voltage of 3.0 V, which was about 78% of its initial capacitance

Summary

Introduction

Supercapacitors (SCs), a kind of electrochemical energy storage device with high power density, long cycle life, and excellent reliability, has been widely used in many fields such as hybrid electric vehicle and high-power output equipment. The introduction of organic solvent reduces the viscosity and increases the conductivity of the pure ionic liquid, and maintains a large electrochemical stability window, which greatly improves the capacitive performance of the device.

Results

Conclusion