Unveiling the redox electrochemical kinetics of interconnected wrinkled microspheres of binary Cu_2-xSe/Ni_1-xSe as battery-type electrode for advanced supercapatteries

Developing a rational design of nanoarchitechtures with excellent electrochemical behaviors is an ultimate and unique strategy to enhance the redox electrokinetics of battery-type electrode materials. Herein, we demonstrate a hierarchical composite comprising interconnected wrinkled micro-solid sphere (ICWMS)-like binary copper selenide/nickel selenide over nickel foam (Cu_2-xSe/Ni_1-xSe/NF) prepared via a wet chemical synthetic protocol and utilized as an effective positrode for improved supercapaterry performance. The binary Cu_2-xSe/Ni_1-xSe/NF electrode considerably improved the electroactive surface area and facilitated ultrafast redox electrochemistry in an alkaline electrolyte medium. Remarkably, the binary Cu_2-xSe/Ni_1-xSe/NF electrode afforded the highest specific capacity of 368 ± 1C/g at 1 A/g greater than that of pristine single selenide electrodes (Cu₂Se and NiSe) in a three-electrode setup which might be attributed to its large surface area, synergism between Ni and Cu, and specific morphology. Moreover, a coin cell supercapattery with the binary Cu_2-xSe/Ni_1-xSe/NF positrode and a porous activated carbon-on-nickel-foam negatrode was constructed, which exhibited excellent energy-storage characteristics in terms of capacity (87.5 ± 1 mAh/g), specific energy (39.3 Wh kg⁻¹), specific power (450 W kg⁻¹), and capacity retention (91.8 %). This simple fabrication approach of hierarchically designed Cu_2-xSe/Ni_1-xSe/NF paves the way for utilizing it as the promising positrode for high-performance supercapattery.