Two-step electrodeposition synthesis of lamellar Ni@NiCo phosphate heterostructures as cathodes for high-performance hybrid supercapacitors

Porous structures grown in situ increase the electrode contact area with the electrolyte, reduce ion diffusion distance, and enhance electrode material electrochemical properties. In this paper, we have adopted a dualchannel electrodeposition strategy with simultaneous electrodeposition and phosphorylation to construct metal-semiconductor contact heterostructures by depositing Ni@NiCo phosphate microspherical nanostructures directly on a copper foam (CF) (Ni@NiCoP/CF) framework at room temperature. The results show that Ni@NiCoP/CF has excellent electrochemical performance with a high specific capacity of 200 mAh g-1 at 1 A g-1, 147.2 mAh g-1 at 20 A g-1 and 93.6 % after 5000 cycles, showing excellent ration performances and cycling stability. In addition, the hybrid supercapacitor composed of Ni@NiCoP/CF as the positive electrode and activated carbon as the negative electrode achieves a high energy density of 48.7 Wh kg-1 at 874 W kg-1 and has excellent cycling stability with 113.23 % capacity retention after 30,000 charge/discharge cycles at a high current density of 10 A g-1. This study serves as a guide for the development of high-performance capacitor cathode materials with high electrochemical activity and capacity.