Utilizing Waste Cable Wires for High-Performance Fiber-Based Hybrid Supercapacitors: An Effective Approach to Electronic-Waste Management

In recent years, electronic waste (e-waste) such as old cable wires, fans, circuit boards, etc., can be often seen in large piles of leftover in dumping yards. Employing these e-waste sources for energy storage devices not only increases the economic value but also decreases the reliance on fossil fuels. In this context, waste cable wires are utilized to obtain precious copper (Cu) fibers and used as a cost-effective current collector for the fabrication of fiber-based hybrid supercapacitor (FHSC). With the braided Cu fibers, forest-like nickel oxide nanosheet grafted carbon nanotube coupled copper oxide nanowire arrays (NiO NSs@CNTs@CuO NWAs/Cu fibers) are designed via simple wet-chemical approaches. As a battery-type material, the forest-like NiO NSs@CNTs@CuO NWAs/Cu fiber electrode shows superior electrochemical properties including high specific capacity (230.48 mA h g⁻¹) and cycling stability (82.72%) in aqueous alkaline electrolyte. Moreover, a solid-state FHSC is also fabricated using forest-like NiO NSs@CNTs@CuO NWAs/Cu fibers as a positive electrode and activated carbon coated carbon fibers as a negative electrode with a gel electrolyte, which also shows a higher energy and power densities of 26.32 W h kg⁻¹ and 1218.33 W kg⁻¹, respectively. The flexible FHSC is further employed as an energy source for various electronic gadgets, demonstrating its suitability for wearable applications.