Hierarchical flower-like AlOOH/CoO(OH) nanocomposite electrodes for high-performance supercapacitors

In this research, aluminum/cobalt oxy-hydroxide (CoAl) thin films were successfully deposited using the layer-by-layer (LbL) method at RT. CoAl nanocomposites were grown on a stainless-steel substrate for 10, 20, and 30 LbL cycles. The structural analysis of CoAl was performed using X-ray diffraction and Fourier transform infrared spectroscopy analyses. The FESEM analysis revealed a three-dimensional flower-like porous nanostructure of the composite. A three-electrode system was employed for electrochemical testing, with the produced AlOOH/CoO(OH) binary composite acting as the working electrode. The electrochemical characteristics of the CoAl samples were analysed in a 1 M KOH aqueous electrolyte. Among 10, 20, and 30 LbL cycles, the 20 LbL cycles nanocomposite exhibited the outstanding specific capacity of 2421 C g^-1@ 5 mV s^-1 within a potential range of 1.4 V. The nanocomposite exhibits pseudocapacitive battery-type behaviour. The remarkable electrochemical activity of the 20 LbL nanocomposite can be ascribed to the lower resistances identified in the sample through EIS analysis and the high surface area of the interconnected nanosheets that form a porous, nano flower-like structure. The combination of AlOOH with CoO(OH) contributes to an improvement in its charge storage capability.