Hydrothermal synthesis of spinel copper cobaltite nanofibers for high-performance energy storage

Copper cobaltite (CuCo 2 O 4 ) is a promising material for energy storage applications due to its excellent electrochemical properties, high conductivity, and superior energy storage capacity. Most previous reports have concentrated on compositional tuning or morphological modifications, while the effect of reaction time on its functional properties has remained largely unexplored. In this study, CuCo 2 O 4 nanofibers were successfully synthesized via a hydrothermal method, and the influence of reaction time on their structural, optical, and electrochemical properties was systematically investigated. X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy confirmed the formation of a pure cubic spinel structure. Detailed electrochemical analysis revealed a specific capacitance of 647.43 F/g at 5 mA/cm 2 , demonstrating excellent cycling stability (>90 % retention) and efficient electron transport. An asymmetric supercapacitor fabricated using CuCo 2 O 4 as the cathode exhibited high performance, with a power density of 4988.27 W/kg and an energy density of 28.81 Wh/kg, along with 94.22 % capacity retention over 4000 cycles. The present results not only support the suitability of CuCo 2 O 4 as a high-performance electrode material but also demonstrate that optimizing the reaction time provides a novel and effective route for enhancing performance compared to existing reports. • Facile hydrothermal synthesis of CuCo 2 O 4 nanofibers • Systematic study on the influence of reaction time on the structural, optical, and electrochemical properties • Specific capacitance of 647.43 F/g at 5 mA/cm 2 achieved with excellent cycling stability (> 90 % retention) • Asymmetric supercapacitor delivers 4988.27 W/kg power and 28.81 Wh/kg energy with 94.22 % retention over 4000 cycles