Hierarchical Heterostructured Cuco2o4@Ni3co1-Layered Double Hydroxide Electrode Electrode with Cobalt-Ion Internal Stress for High Performance Hybrid Supercapacitors

Developing high performance supercapacitors is still a major challenge due to limitations in energy density and rate performance. A promising strategy is to employ rational tuning of the electrode structure through interface engineering. In this study, a cobalt-ion internal stress-modulated nickel iron layered double hydroxide (NiCo-LDH) ultrathin materials with larger layer spacing is successfully prepared. NiCo-LDH is directly deposited on CuCo2O4 (CCO) which in-situ grown on copper foam (CF) to form a unique three-dimensional hierarchical structure. This approach effectively increases the number of active sites and resolves the stacking and dead volume issues of NiCo-LDH. As a result, the reaction kinetics of the material are significantly improved, and the electron transport is accelerated. The CCO@NiCo-LDH/CF electrode exhibits exceptional electrochemical properties, including an ultra-high specific capacitance of 18.046 F cm-2 at 5 mA cm-2, high rate performance with 82.9% capacitance retention at 40 mA cm-2, and excellent stability at high current densities. By constructing a CCO@NiCo-LDH//AC hybrid supercapacitor using CCO@NiCo-LDH as positive electrode and activated carbon (AC) as negative electrode, an ideal power density of 51.11 W h kg-1 at 110.58 W kg-1 is achieved, suggesting that this hierarchical heterostructured electrodes have great potential for application in electrochemical energy storage.