Interconnected two-dimensional MnO2 nanosheets anchored on three-dimensional porous Cu skeleton as a high-performance cathode for energy storage

Interconnected two-dimensional (2D) MnO2 nanosheet network anchored on 3D nanoporous Cu skeleton (named as NPC@MnO2) was easily prepared by utilizing the redox reaction between KMnO4 and Cu. The as-prepared trans-dimensional NPC@MnO2 composite, which combined the advantages of high surface area MnO2 nanosheets and 3D integrated conductive NPC skeleton, is equipped with abundant multilevel pore voids, rich active sites and channels for smooth ion and electron delivery. The NPC@MnO2 exhibits decent specific capacitance, admirable cycling and rate capability. At a high current density of 10 A g(-1), the NPC@MnO2 can be durably cycled for more than 10,000 loops with 91.6% capacitance retention. An asymmetric supercapacitor was constructed with NPC@MnO2 and active carbon, and delivered a high energy density of 10.9 Wh kg(-1) (at a power density of 4260 W kg(-1)) and a high capacitance retention of 93.4% over 10,000 cycles at 10 A g(-1). With the merits of easy preparation and superior energy storage performances, NPC@MnO2 holds promising application prospect as a candidate for high performance supercapacitors.