Abstract
This work presents the effect of different contents of graphene foam (GF) on the electrochemical capacitance of nickel phosphate Ni3(PO4)2 nano-rods as an electrode material for hybrid electrochemical energy storage device applications. Pristine Ni3(PO4)2 nano-rods and Ni3(PO4)2/GF composites with different GF mass loadings of 30, 60, 90 and 120 mg were synthesised via a hydrothermal method. The electrochemical behavior of pristine Ni3(PO4)2 and Ni3(PO4)2/GF composites were analysed in a three-electrode cell configuration using 6 M KOH electrolyte. The Ni3(PO4)2/90 mg GF composite sample exhibited the highest specific capacity of 48 mA h g-1 at a current density of 0.5 A g-1. The electrochemical behavior of the Ni3(PO4)2/90 mg GF composite was further analysed in a two-electrode hybrid asymmetric device. A hybrid asymmetric device was fabricated with Ni3(PO4)2/90 mg GF as the cathode and carbonized iron cations (Fe3+) adsorbed onto polyaniline (PANI) (C-FP) as the anode material (Ni3(PO4)2/90 mg GF//C-FP) and tested in a wide potential window range of 0.0-1.6 V using 6 M KOH. This hybrid device achieved maximum energy and power densities of 49 W h kg-1 and 499 W kg-1, respectively, at 0.5 A g-1 and had long-term cycling stability.