Fabrication of an ultra-stable composite electrode material of La₂O₃/Co₃O₄/graphene on nickel foam for high-performance supercapacitors

Stable electrode materials with suitable electrochemical performance and high specific power are essential for the application of supercapacitors. A combination of La₂O₃, Co₃O₄, and graphene on nickel foam (LCGN) was prepared by hydrothermal synthesis and heat treatment to construct a three-dimensional flower-like structure. The synergistic effect between La₂O₃, Co₃O₄, and graphene dramatically improves the electrode stability. Owing to the special three-dimensional flower-like structure that improves ion diffusion and prevents structural collapse during charging and discharging, the prepared LCGN composite exhibits an excellent specific capacitance of 2945.11 F g⁻¹ (2.95 F cm⁻²) at a current density of 1 A g⁻¹ and excellent rate retention of 79.20% at 30 A g⁻¹. Moreover, the LCGN//LCGN symmetric supercapacitor shows excellent performance with a specific capacitance of 403.92 F g⁻¹ at 1 A g⁻¹, with power density and energy density (12 000 W kg⁻¹ at 53.9 W h kg⁻¹), reflecting its industrial potential. Under the condition of 10 A g⁻¹ current density, the capacitance retention rate is still extremely high, 89.3% after 30 000 continuous charge and discharge cycles, which certifies the promising potential of LCGN for high-performance energy storage devices.