In situ synthesis of Cu(OH)2 and carbon nanotube electrodes: A promising approach for high-performance one-dimensional flexible supercapacitors

Amidst the rapid surge in electrical device utilization, there is an urgent need for advanced power supply solutions. Flexible supercapacitors, renowned for their remarkable electrochemical properties, emerge as a promising remedy. This study employs in situ techniques on copper wire (CW) to obtain active materials for both the electrodes. The positive CW@Cu(OH)₂ electrode, synthesized through vapor-phase reaction between CW and NH₃·H₂O, yields copper hydroxide (Cu(OH)₂) nanosheets via an alkali-assisted oxidation process. Comparative analysis of CW@Cu(OH)₂ electrodes under varying reaction conditions revealed that the Cu(OH)₂ nanosheets, characterized by their small size and high distribution density on CW, significantly enhance electrochemical performance. The optimized CW@Cu(OH)₂ electrode achieved a specific capacitance of 195.7 mF cm⁻². This in situ growth method effectively prevents active material detachment, resulting in electrodes with minimal internal resistance. Carbon nanotubes (CNTs), also synthesized in situ via chemical vapor deposition on CW, serve as the active materials for the negative electrode. Assembled in parallel, the flexible supercapacitor, CW@Cu(OH)₂//KOH-PVA//CW@CNTs, achieves a specific capacitance of 1.59 F cm⁻³ at a current density of 0.1 A cm⁻³, with an energy density of 0.496 mWh cm⁻³ at a power density of 15 mW cm⁻³. Demonstrating robust capacitance retention across varying current densities and diverse bending angles, this supercapacitor signifies a versatile and stable power storage solution.