Electrochemical evaluation of low-cost flexible supercapacitors based on nickel-coated activated carbon textile electrodes.

This study presents the development of low-cost flexible supercapacitors (SCs) based on cotton textile electrodes impregnated with activated carbon (AC) and coated with nickel via sputtering. The electrochemical performance was optimized by varying the activated carbon (AC) ink immersion cycles (1, 3, and 5 immersions, corresponding to 0.0727, 0.2041, and 0.2936 grams, respectively) and the sputtered nickel amount (0.011, 0.002, 0.0029, and 0.0032 grams corresponding to 1, 3, 10 and 15 minutes of deposition, respectively). We found that a moderate nickel deposition improved electron transport and reduced charge transfer resistance, while excessive deposition can block pores and decrease capacitance, nevertheless the presence of nickel improves the stability of the device, for example, the configuration of the electrodes with 0.2041 g of AC and 0.002 g of Ni shows a specific capacitance of 382.40 mF cm-2 (at 5 mV s-1) and a high stability (95.76%) after 1000 cycles. These findings demonstrate that balancing carbon and nickel coating content is a critical parameter for the good electrochemical performance of SCs. This work advances the design of flexible, lightweight, and wearable supercapacitors, paving the way for high-performance and sustainable energy solutions for portable electronics and sustainable energy storage.