Soumya Rai, Chhaya Ravi Kant
The rational design of nanostructured heterophase materials has emerged as an effective strategy for enhancing charge storage and transport in electrochemical energy-storage systems. Herein, a dual-phase CoS2/Co3S4nanostructured heterostructure was synthesized via a hydrothermal route and investigated as an electrode material for supercapacitors. Structural characterization confirmed the formation of crystalline CoS2and Co3S4phases, while electron microscopy revealed hierarchical micro-nanostructures composed of interconnected nanoparticles that provide abundant electrochemically active interfaces. The electrochemical charge storage behavior was systematically evaluated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy in both three- and two-electrode configurations. Detailed kinetic analysis usingb-value determination and Dunn's model demonstrated the combined contribution of surface-controlled and diffusion-governed charge-storage processes. The electrode delivered a specific capacitance of 716.8 F g-1at 0.5 A g-1in a three-electrode system. In a two electrode configuration, the symmetric supercapacitor delivered a capacitance of 303.3 F g-1with an energy density of 2.42 Wh kg-1at a power density of 60 W kg-1. The device also demonstrated appreciable electrochemical stability with capacitance retention of 90% and 88% after 2000 charge-discharge cycles in three- and two-electrode systems, respectively. The enhanced performance is attributed to heterophase-induced charge-transfer pathways and improved ion accessibility arising from the hierarchical nanostructure. This study highlights the role of intrinsic phase-engineered cobalt sulfide nanostructures in governing electrochemical functionality and provides insights for the development of advanced nanomaterials for next-generation energy-storage technologies.