Hierarchical core–shell CoMn2O4@MnO2 nanoneedle arrays for high-performance supercapacitors

Abstract

Hierarchical mesoporous core–shell CoMn₂O₄@MnO₂ nanoneedle arrays on nickel foam have been manufactured via a two-step hydrothermal process. Electrochemical performances of the CoMn₂O₄@MnO₂ nanomaterials have been tested for supercapacitors and demonstrated outstanding properties. The CoMn₂O₄@MnO₂ electrode delivers a specific capacitance of 2126 F g⁻¹ at a current density of 1 A g⁻¹ in 2 M KOH aqueous solution and also shows an excellent cycling stability, which retains 94.4% of the initial capacitance after 5000 charge/discharge cycles at a current density of 4 A g⁻¹. The result confirms the superiority of the CoMn₂O₄@MnO₂ electrode compared with the CoMn₂O₄ electrode and demonstrates the potential application of the CoMn₂O₄@MnO₂ nanoneedle array electrode for high-performance energy storage device applications.