Nickel hexacyanoferrate flower-like nanosheets coated three dimensional porous nickel films as binder-free electrodes for neutral electrolyte supercapacitors

Abstract

Nickel hexacyanoferrate (NiHCF) flower-like nanosheets coated three dimensional (3D) hierarchical porous Ni composite films are successfully prepared by the combination of hydrogen-bubble template electro-deposition and electrochemical polymerization methods. The novel 3D porous NiHCF/Ni composite films demonstrate excellent electrochemical performance as binder-free integrated electrodes for supercapacitors in KNO3 neutral electrolyte. Comparing to the NiHCF coated on smooth Ni film, the 3D hierarchical porous NiHCF/Ni film electrodes exhibit about 10 times larger specific capacitance in KNO3 neutral electrolyte. The 3D porous NiHCF/Ni film electrodes also illustrate good long-term stability for about 18,000 charge-discharge cycles. The improvement of electrochemical performance might be ascribed to the large specific area, highly conductive pathway and fast ion diffusion for the flower-like NiHCF nanosheets directly growth on the 3D hierarchical porous interconnected conductive scaffold current collectors.