Flocculent Ternary Nickel-Cobalt-Iron Hydroxide Electrode Material: Preparation and Performance for Electrochemical Energy Storage

Three electrode materials of nickel-cobalt hydroxide, nickel-iron hydroxide, and nickel-cobalt-iron hydroxide were synthesized on nickel foam (NF) via a one-step solvothermal method. The electrochemical tests showed that the ternary nickel-cobalt-iron metal electrode with the best energy storage performance outperforms the other two binary metal electrodes, and it could reach an area capacitance of 5.11 F.cm(-2) at a current density of 2 mA.cm(-2). To further investigate the practical application, an asymmetric supercapacitor was assembled with NiCoFe - OH/NF as the positive electrode and activated carbon as the negative electrode, respectively, and the device achieved a maximum energy density of 5.994 Wh.m(-2) at a power density of 46.814 W.m(-2). The results show that the excellent performance of NiCoFe - OH/NF can be attributed to loosen flocculent structure, which provides larger specific surface area per unit volume and subsequently store more electric charges, as well as facilitate electron/ion transportation, reduce the contact resistance between active material and electrolyte, and increase the electrical conductivity.