Facile synthesis of N-doped NiCo-LDH nanowire with rich oxygen vacancies by nonthermal plasma for high-performance asymmetric capacitor electrode

Layered double hydroxides (LDHs) have been served as potential pseudo-capacitive materials, especially for high-performance supercapacitors. However, the characteristics like limited capacitance, poor conductivity, and stability of LDHs severely confine their extensive applications for future energy-storage devices. It is urgent to seek a new and simple method to modify LDH materials, to improve its electrochemical performance and apply it to supercapacitors. Herein, a facile in-situ non-thermal plasma (NTP) treatment is conducted to modify NiCo-LDH nanowires for better electrochemical performance, resulting from the introduction of N-doping and oxygen vacancies by N2 NTP. All these instructive synergies provide the optimum electrode (P-NiCoNW/CC-150) after the NTP treatment under the power of 150 W with outstanding capacitance performance of 4320 mF/cm2 at 2 mA/cm2, and superior cycling stability along with capacitance retention of 117.3 %. Most importantly, an asymmetric supercapacitor device is assembled, employing P-NiCoNW/CC-150 and oxidized carbon cloth as cathode and anode electrodes respectively, exhibiting a particularly high energy density of 364 μWh/cm2 when the power density is 4505 μW/cm2. This work confirms a feasible and green NTP method to synthesize high-performance electrodes for practical applications in future energy-storage devices but not limited to supercapacitors.