NaMnO2−x thin nanosheets assembled microspheres as electrode for aqueous asymmetric supercapacitor

• Published in: Materials research express Vol. 7; no. 3; pp. 035508 - 35515
• Main Authors: Xu, Song, Wan, Tao, Zhou, Kai-bin, Zhu, Guang-ming, He, Zhi-qiang, Huang, Hai-bo, Zhou, Ting, Mao, Wen-qi, Wu, Jie-jun, Gong, Shang-kun, Qiao, Yan-xin
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.03.2020
• Subjects: Activated carbon; asymmetric; Capacitance; Current density; Electrodes; Flux density; Manganese dioxide; Microspheres; Nanosheets; Oxygen evolution reactions; oxygen vacancies; pre-insertion; supercapacitor; Supercapacitors
• ISSN: 2053-1591
• DOI: 10.1088/2053-1591/ab815a

This study proposes MnO2 thin nanosheets assembled microspheres with oxygen vacancies and pre-insertion of Na ions (NaMnO2−x) as highly capable supercapacitor electrodes. The NaMnO2−x electrode can reach a stable potential window of 1.2 V without oxygen evolution reactions in three-electrode configuration. The voltage window of the assembled aqueous ASC device can be expanded to 2.4 V (1 M Na2SO4) by using NaMnO2−x electrode and activated carbon electrode as positive and negative electrodes, respectively. The NaMnO2−x electrode delivers a good specific capacitance of 215 F g−1 at current density of 1 A g−1. It displays high-rate capability and an excellent cycling stability, maintaining 95.5% of its initial specific capacitance at 2 A g−1 after 2500 cycles. The ASC device shows a high energy density and power density of 28.56 W h kg−1 and 1246 W kg−1, respectively, at a current density of 1 A g−1.