Deposition of Ni(OH)2 on nickel substrate using vacuum kinetic spray and its application to high-performance supercapacitor

Abstract

Herein, we report a direct deposition of nano-structured Ni(OH)2 from micro-sized Ni(OH)2 powder on nickel sheet and nickel foam using nano-particle deposition system, one of the low-vacuum and room temperature vacuum kinetic spray processes. In this work, the deposition of the Ni(OH)2 powder on nickel sheets is carried out with various stand-off-distances (SoDs) and carrier gas pressures. The deposited films are investigated by field-emission electron microscopy, X-ray diffraction, and Raman spectroscopy. The crystallite size of the nano-structured Ni(OH)2 depends on the SoD and the carrier gas pressure. The electrochemical performance of Ni(OH)2 deposited on nickel sheets is measured by cyclic voltammetry in the 3-electrode cell. The deposition with 5 mm SoD and 0.3 MPa carrier gas pressure is found to be the optimum deposition condition for the nano-structured Ni(OH)2 thin film as an electrode material. The nano-structured Ni(OH)2 thin film deposited with 5 mm SoD and 0.3 MPa carrier gas pressure on nickel foam demonstrates a specific capacitance of 2377 F g−1 at 2 mV s−1 scan rate and 2092 F g−1 at 1 A g−1 current density and excellent cyclic stability for 3000 cycles with 83% capacitance retention.