A microwave plasma etching strategy for preparing oxygen-vacancy-rich NiCoO2 Nanoarrays for high-rate performance supercapacitor

Supercapacitors are vital for industries like automotive and energy storage. Transition metal oxides are promising electrode materials due to their diversity and high capacity. This study uses microwave plasma etching (MPE) to synthesize oxygen-vacancy-rich NiCoO2 nanoarrays (E-NCO) for supercapacitors. The etched NiCoO2 nanoarrays exhibit remarkable performance (1360.7 F g−1 at 1 A g−1) and excellent rate performance (996.7 F g−1 at 50 A g−1) in a three-electrode system. After assembling E-NCO-15 into a hybrid supercapacitor, it demonstrated a high energy density of 48.4 Wh kg−1 at the power density of 387.4 W kg−1, and even at the ultra-high power density of 19377.1 W kg−1, the energy density remains 15.2 Wh kg−1. Through the characterization of the material and an exploration of the reaction kinetics mechanism, it was discovered that MPE as a low-cost and easily controllable material modification method can introduce oxygen vacancies into the material, thereby enhancing both the material’s electrical conductivity and charge storage capacity. In addition, nanoarrays morphology provides more active sites and faster ion transport. These results highlight E-NCO’s potential for high-performance supercapacitors.