Nanoneedles anchored ultrathin petals of CuCo layered double hydroxide with high areal capacitance and long cycle life for high-performance hybrid supercapacitors

This work demonstrates a simple one-step solvothermal strategy to develop high-performance self-supported architectured hybrid electrode materials of CuCo-layered double hydroxide on Ni foam. The novel advanced self-supporting architecture of CuCo–LDH with sharp nanoneedles penetrating the ultrathin petals, and thus forming a 3D structure, realizes ultrahigh areal capacitance. With high specific area, such a hybrid electrode material exhibits high areal capacitance of 7.02 F·cm⁻² at higher current density of 30 mA·cm⁻². Moreover, it gives a huge cycling life of 96.60 % over 10,000 cycles, and high-rate capability. The enormous electrochemical performance is attributed to the combined advantages of a hierarchical hybrid structure, such as the shortening of ion diffusion path, and the provision of superior pathways for redox reaction between the ions of electrolytic medium and cations of CuCo at the surface of an electrode. When the cathode of this hybrid architecture is coupled with an AC anode, the ASC device exhibits a high volumetric capacitance of 2421.88 mF·cm⁻² at a higher current density of 10 mA·cm⁻², capacitance retention of 91 % over 15,000 charge–discharge cycles, and volumetric energy density of 0.87 mWh·cm⁻³ and power density of 25 mW·cm⁻³. The practical applicability of such a high-power ASC device was demonstrated by lighting different light-emitting diodes. This work invokes the design and development of high-performance potential supercapacitor electrodes for future wearable and electronic device applications.