Flexible and Twistable ZnMn₂O₄-Electrodeposited Yarn Supercapacitors for Wearable Electronics

The growing demand for wearable electronics has driven interest in flexible fiber-based supercapacitors (F-SCs) as power sources, offering tunable sizes, adaptable shapes, and versatile design possibilities. This study presents the fabrication of a highly flexible and twistable fiber-shaped yarn supercapacitor (F-SC) via direct electrodeposition of ternary metal-oxide nanostructures (ZnMn₂O₄) onto flexible and conductive carbon yarn substrates. The uniform growth of ZnMn₂O₄ nanostructures on the carbon yarn not only enhances the capacitive performance of the fabricated devices but also significantly enhances the mechanical integrity of the electrodes, ensuring excellent bending and electrochemical stability for the F-SC device. The device exhibits a high areal capacitance of 87.6 mF/cm² at a scan rate of 10 mV/s and 35.4 mF/cm² at a current density of 0.1 mA/cm². Furthermore, it retains 92% of its capacitance after 10,000 charge–discharge cycles, achieving energy and power densities of 11 μWh/cm² and 385 μW/cm², and maintaining consistent performance under varying bending and twisting conditions. This work offers a simple, cost-effective, and efficient strategy for developing flexible and twistable fiber electrodes using a straightforward electrodeposition process. The fabricated electrodes hold great potential in developing flexible energy storage technologies and enabling seamless integration into next-generation portable and wearable electronics.