Nickel cobaltate/nickel cobalt layered double hydroxide composites as electrodes for asymmetric flexible...

The electrochemical performance of electrode materials plays a pivotal role in determining the practical applicability of flexible supercapacitors, and optimization of material morphology has emerged as an effective strategy to augment these properties. This study presents the preparation of nickel cobalt cobaltite (NiCo₂O₄) nano-arrays exhibiting various morphologies, which serve as a support matrix. This is achieved through hydrothermal and annealing treatments applied to the surface of activated carbon cloth (CC). Subsequently, cobalt-nickel layered double hydroxide (CoNi-LDH) is synthesized onto these nano-arrays via electrochemical deposition, resulting in the formation of CC/NiCo₂O₄/CoNi-LDH (CC/NCCN) electrode. The constructed asymmetric supercapacitor based on CC/NCCN as the positive electrode demonstrates a 1.7 V voltage window. It achieves 137.88 F g^-1 specific capacitance at a 1 A g^-1, and 55.35 W h kg^-1 energy density at 850.12 W kg^-1 power density. In addition, it demonstrates remarkable flexural resistance, exhibiting a capacitance retention of 96.29 % following 500 flexural cycles. Furthermore, the device retains 90.55 % of capacitance while achieving nearly 100 % coulombic efficiency after undergoing 10,000 cycles. This device demonstrates substantial promise for a wide range of future applications, and the findings provide innovative insights for advancing the development of flexible devices.