One-step construction of δ-MnO2 cathodes with an interconnected nanosheet structure on graphite paper for high-performance aqueous asymmetric supercapacitors. (March 2021)

• Record Type: Journal Article
• Authors: Xie, Wenlu; Wang, Jun; Long, Xiao; Wang, Xiao; Zou, Situo; Zhang, Li; Xu, Huazhuo; Fu, Yujun; Liu, Dequan; Li, Yali; Li, Junshuai; He, Deyan
• Is Part Of: Journal of energy storage. Volume 35(2021)
• Publication Date: 2021-03
• Subjects: Interconnected δ-MnO2 nanosheets -- Aqueous asymmetric supercapacitors -- High specific energy -- Long cycle stability; Energy storage -- Periodicals; Energy storage -- Research -- Periodicals; 621.3126
• DOI: 10.1016/j.est.2021.102308
• Languages: English
• ISSNs: 2352-152X

Abstract

Highlights: One-step water bath at 40°C to grow self-supporting δ -MnO2 electrodes. 446.6 F g –1 at 1 A g –1 and wide potential window of 0-1.3 V for the electrode. 47.2 Wh kg −1 at 1150.0 W kg −1 and good stability of 30000 cycles for the aqueous ASCs. Abstract: Among various supercapacitor materials, transition metal oxides have attracted wide attention due to their high theoretical capacitance, and however a great challenge associated with the related materials is to fabricate nanostructured electrodes with high comprehensive performance including high capacitance, excellent cycle stability and good rate performance by a simple and green method. Herein, a high-performance self-supporting cathode consisting of interconnected δ -MnO2 nanosheets on graphite paper (GP) is developed by water bath only at 40°C. Benefiting from the synergetic effects from the interconnected and open nanosheet structure of δ -MnO2 and the GP substrate including effective contact with the electrolyte, a large specific surface area, efficient stress relief, improved ion diffusion and charge transfer, and small equivalent series resistance, a high specific capacitance of 446.6 F g –1 at 1 A g –1, 1.3 V potential window, and outstanding cycle stability with the capacitance retention of ~ 86.1% after 10000 cycles at 8 A g –1 and Columbic efficiency around 100% during cycling can be achieved for the cathodes. The aqueous asymmetric supercapacitors assembled using the δ -MnO2 cathode and active carbon anode and 1 M NaNO3 aqueous solution electrolyte can deliver a specific energy of 47.2 and 19.8 W h kg −1 at 1150 and 115000 W kg −1, respectively. Moreover, long cycle stability with 87.2% capacitance retention even after 30000 cycles at 4 A g −1 can be maintained by the ASCs. Thanks to the simple and green preparation and high performance of the electrodes, valuable exploration of developing high-performance ASCs can be provided by this work.