Molten-salt synthesis of lamellar Ni(OH)2/NiOOH composite and its application for pseudocapacitor

A novel improved molten-salt synthesis was employed to synthesize the Ni(OH)2/NiOOH composite by using a mixed precursor of nickel nitrate and nickel acetate. Here, the molted salt was used as reactant for the first time, rather than a reaction medium in the conventional molten salt method. The synthesized Ni(OH)2/NiOOH composite possesses loose lamellar structure, which could facilitate the transport of electrolyte ions during the rapid charge/discharge process. The capacitive properties of the composite were evaluated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques in 6 M KOH aqueous electrolyte. Electrochemical results shown that the Ni(OH)2/NiOOH composite which obtained with this nickel acetate assisted route was endowed with high pseudocapacitance performance of 1425 F g−1 at 2 A g−1. The material exhibited moderate rate capability, high energy density of 59.85 W h kg−1 and high power density of 0.55 kW kg−1.