Zincronized NiCo selenides coupled with polypyrrole: a synergistic route to high-energy asymmetric supercapacitors

Transition metal selenides have gained significant attention for energy storage applications due to their outstanding electrochemical properties, excellent theoretical capacity, superior conductivity, and eco-friendly nature. The dual strategy consists of incorporating zinc into nickel cobalt selenide to optimize its electronic structure and redox kinetics, combined with the integration of a conductive polymer matrix to enhance the charge transport mechanism. However, there is still room for improvement in energy density and storage capability which can be achieved via composites with conducting polymers. To enhance the electrochemical performance of NiCoSe₂-Zn15, polypyrrole (PPy) was incorporated through a physical mixing approach. This strategic modification significantly improved electrical conductivity, ion diffusion, and structural stability of the synthesized electrode material. Different structural and morphological characterization methods have been employed to verify the successful synthesis of the selenide materials. The electrochemical performance of all electrodes in the three-electrode configuration was evaluated, revealing that the NiCoSe₂-Zn15/30PPY sample exhibited remarkable results. The optimized sample demonstrated outstanding specific capacities of 2252.6 C g^-1 at 2 mV s^-1 and 1370.5 C g^-1 (1957.9 F g^-1) at 0.5 A g^-1. Most importantly, the NiCoSe₂-Zn15/30PPY‖AC supercapattery device was successfully fabricated, achieving an energy density of 130.7 Wh kg^-1 and a power density of 11 900 W kg^-1. The hybrid device exhibited excellent cyclic stability, retaining 94.3% of its initial capacity after 5000 cycles. The hybrid nature of the NiCoSe₂-Zn15/30PPY‖AC was further validated using Power's law and Dunn's model. This study highlights the potential of selenide-based nanocomposites as viable battery-grade electrode materials in asymmetric supercapacitor (ASC) devices.