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

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

JOURNAL=Frontiers in Chemistry

VOLUME=7

YEAR=2019

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00664

DOI=10.3389/fchem.2019.00664

ISSN=2296-2646

ABSTRACT=<p>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 (Py<sub>13</sub>DFOB) 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<sup>−1</sup>. The energy and power density of EDLCs using Py<sub>13</sub>DFOB in the PC electrolyte reach 39.06 Wh kg<sup>−1</sup> (100 mA g<sup>−1</sup>) and 8.03 kW kg<sup>−1</sup> (5,000 mA g<sup>−1</sup>), respectively, at the working voltage of 3.0 V, significantly exceeding the performance of commercial electrolyte tetraethylammonium tetrafluoroborate (TEABF<sub>4</sub>). The results indicate that Py<sub>13</sub>DFOB can be a promising electrolyte salt for supercapacitor.</p>