Production of AgCu:NiO/Ni foam electrode with high charge accumulation and long cycling stability

Abstract

Nickel oxide is a promising material for electrochemical energy storage devices due to its high specific surface area, rapid redox reactions, and short diffusion path in the solid electrode. It has been known that the loading of metallic elements into the NiO matrix enhances these superior properties. NiO material is electrochemically deposited on Ni foam, and then, Ag and Cu thin layers are coated on NiO by thermal evaporation. The produced NiO/Ni foam and AgCu:NiO/Ni foam electrodes are annealed at 400 degrees C for 1 h. Those are utilized as anode for high-performance energy storage electrode in an alkaline solution. The former has an energy density of 56.9 Wh kg(-1) at 3155.5 W kg(-1), while the latter has a high energy density of 107.6 Wh kg(-1) at the corresponding power density of 2957.7 W kg(-1). Although specific capacitance of the former decreases to 46.2% of its original capacitance at 10 A g(-1) after 5000 cycles, the latter exhibits higher cycling stability with 71.0% retention after 5000 charge-discharge cycles owing to the loading of Ag and Cu into NiO matrix. Charge transfer resistance of NiO/Ni foam, which is inversely proportional to electroactive surface area, reduces from 19.4 to 0.28 omega after the incorporation of Ag and Cu. Compared to NiO/Ni foam, AgCu:NiO/Ni foam with a higher electroactive surface area is more appropriate for charge accumulation. As mention above, the features of AgCu:NiO/Ni foam indicate that it is a promising material as an effective start-of-art energy storage device.