Fabrication of Bismuth-doped Co–Ni spinel ferrite electrodes for enhanced cyclic performance in asymmetric supercapacitors

The development of innovative and electrochemically efficient energy storage systems is the key to explore advanced electrode materials. Current work presents a facile and cost-effective strategy to synthesize bismuth (Bi) doped spinel ferrites nanoparticles Co–Ni/Bi for high-performance electrode fabrication. Although Bi ferrites possess high capacity owing to multi electron redox reactions, they suffer from cycle stability and rate capability. Addressing these limitations, the cyclic performance of the supercapacitor is highly improved by Bi-doped spinel ferrite nanoparticles Co_0.5Ni_0.5Bi_xFe_1.5-xO₄, (Co–Ni/Bi) where (x=0.00, 0.02 and 0.08). The CB/Co–Ni/Bi, (x=0.02) electrode showed a superior specific capacitance of 125.79 F g⁻¹ at 0.2 A g⁻¹, without a noticeable decay in the cycle number after 6000 cycles and these advantageous cyclic stabilities can be described by the electrochemical contribution of Bi in the porous nanostructure. The supercapacitor with the same electrode showed the high energy density of 26.21 Wh kg⁻¹ at a power density of 100 W k g⁻¹.