One-pot growth of Co(OH)2 nanowire bundle arrays on in situ functionalized carbon cloth for robust flexible supercapacitor electrodes

Abstract

A one-pot route for coaxial growth of crystallized Co(OH)₂ nanowire arrays on flexible carbon cloth (Co(OH)₂/CC) has been developed for high-performance bendable pseudocapacitive electrodes. The hydrothermal process is found to result in in situ generation of hydrophilic groups on CC (in situ functionalized), changing its wettability and simultaneously helping the nucleation of Co(OH)₂. Electrochemical tests evidence that the Co(OH)₂/CC can function as a high-performance electrode with a high areal capacitance up to ∼1.13 F cm⁻², excellent cycling performance (nearly 100% capacitance retention after programmed 4000 cycles) and good rate capability (retaining 46.7% of its maximum capacitance at a high current density of 40.8 mA cm⁻²). More importantly, detailed bending tests further demonstrate that the electrode possesses a good mechanical endurance. Even with an extreme bending radius, the majority of the nanowire arrays can still survive and the electrode shows small changes in capacitance (only 7.5% loss) and impendance (<11%) compared to the unbent state. The unique mechanical merits of array architecture for robust flexible electrode design are put forward. Our work provides a direct strategy to grow ordered nanoarray energy storage electrodes with in situ functionalization of the current collector to achieve robust mechanical and electrical adhesion.