High-performance asymmetric supercapacitor electrode materials based on CoSe2@NiCo-LDH@Ni foam†

Abstract

Layered double hydroxides (LDHs), as materials with high energy density and tunable structural properties, have been widely employed to enhance the performance of supercapacitor electrodes. However, the limitations in mechanical stability and conductivity of LDH materials continue to hinder their practical applications. To address these issues, this study proposes the construction of a heterostructure by combining transition metal selenides with NiCo-LDHs, aiming to improve the conductivity and electrochemical performance of electrode materials. CoSe₂, with its excellent electronic conductivity, forms a synergistic effect when integrated with the layered structure of NiCo-LDHs. This composite material not only enhances the contact area between the electrode material and the electrolyte but also increases the charge transfer rate and improves the cycling stability of NiCo-LDHs. Furthermore, the nanospheroidal structure of CoSe₂ and the layered structure of NiCo-LDHs collaboratively optimize the surface properties of the material, thereby boosting the energy density of the supercapacitor. The fabricated cathode delivers a high specific capacitance of 4180 mF cm⁻² (1100 F g⁻¹) at 5 mA cm⁻². Additionally, by combining the composite material cathode with an activated carbon anode, a high-performance hybrid supercapacitor was developed, demonstrating 81% capacity retention after 10 000 cycles. These findings highlight the rational design of the heterostructure composite material cathode, significantly advancing its commercialization potential.