Freestanding Interconnected Mno2 Nanosheets with Flower Structure Grown on Ni Foam for High-Performance Supercapacitor

In this paper, MnO 2 nanosheets were prepared by decorating with ZIF-8-derived template grown on Ni foam to obtain a novel binder-free highly conductive electrode with a uniform flower-liked morphology. The abundant groups on PDA-pretreatment Ni foam promote the highly dispersed of assembled ZIF-8 nanocrystals. The as-prepared composites are converted into hierarchically porous mixture of ZIF-8 and ZnO by a convenient carbonization process. After a hydrothermal process, MnO 2 nanoflowers with extremely exposure of active sites composites show excellent electrochemical performance for supercapacitor applications. It exhibits a maximum specific capacitance of 2005 F g −1 at a current density of 2 A g −1 . Furthermore, an asymmetric device was assembled comprising this electrode and commercial activated carbon as negative and positive electrodes, respectively. This assembled device yielded a maximum energy density of 70.57 Wh kg -1 and a maximum power density of 12.45kW kg -1 with 94.04% capacity retention after 8000 charge–discharge cycles, which is superior for SC devices