Rational design of asymmetric supercapacitors via a hierarchical core-shell nanocomposite cathode and biochar anode

• Published in: RSC advances Vol. 9; no. 72; pp. 42543 - 42553
• Main Authors: Fan, Meiqing, Zeng, Xu, Yang, Xiaodong, Zhang, Xin, Ren, Bo
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 20.12.2019; The Royal Society of Chemistry
• Subjects: Activated carbon; Asymmetry; Buckwheat; Chemistry; Core-shell structure; Cycles; Diffusion length; Electrochemical analysis; Flux density; Ion diffusion; Manganese dioxide; Microprocessors; Microspheres; Nanocomposites; Nanosheets; Nickel oxides; Shells; Stability analysis; Supercapacitors
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/c9ra09142d

Hierarchical MnO nanosheets attached on hollow NiO microspheres have been designed by a facile hydrothermal process. The core-shell structure is achieved by decorating an MnO nanosheet shell on a hollow NiO sphere core. The highly hollow and porous structure exhibits a high surface area, shortened ion diffusion length, outstanding electrochemical properties (558 F g at a current density of 5 mA cm ), and excellent cycling stability (83% retention after 5000 cycles). To further evaluate the NiO/MnO core-shell composite electrode for real applications, three asymmetric supercapacitors (NiO/MnO //pomelo peel (PPC), NiO/MnO //buckwheat hull (BHC), and NiO/MnO //activated carbon (AC)) are assembled. The results demonstrated that NiO/MnO //BHC delivered a substantial energy density (20.37 W h kg at a power density of 133.3 W kg ) and high cycling stability (88% retention after 5000 cycles) within a broad operating potential window of 1.6 V.