Revealing an optimal asymmetric supercapacitor with niobium-zinc-cobalt multiphase oxide electrode: Engineered for enhanced performance and reliability

Rising global energy demands necessitate the development of effective and sustainable energy storage solutions. This work explores the synthesis and optimization of niobium zinc cobalt (NbZnCo) multiphase oxide composite electrodes via hydrothermal method for energy storage applications. The influence of varying hydrothermal reaction time is assessed, revealing that optimum reaction time facilitates optimal particle formation and enhances electrochemical performance. Structural, morphological characterizations, and electrochemical measurements are thoroughly analyzed to assess the material properties and performance. The optimized sample, designated as NZC-12, exhibits superior energy storage characteristics, delivering an areal capacitance of 17.15 F/cm2 at 10 mA/cm2 and an energy density of 0.38 mWh/cm2 at 2 mW/cm2, attributed to electrode features, that promotes effective ion diffusion, efficient charge transfer, and high carrier mobility. Long-term stability tests show that NZC-12 maintains 86.5% of its initial capacitance after 10,000 charge-discharge cycles. To further validate its applicability, an asymmetric supercapacitor device is fabricated using NZC-12//activated carbon electrodes, achieving an areal capacitance of 771.8 mF/cm2, energy density of 0.107 mWh/cm2, and power density of 5 mW/cm2. These findings emphasize that NbZnCo oxide composite is a highly potential material for future energy storage systems, offering a compelling combination of high performance with long-term stability for advanced energy storage applications.