Manganeseoxide with rich oxygen vacancies based on plasma modification for high performance supercapacitors

Herein, the flower-like manganese oxide was synthesized by a hydrothermal method, and then modified by plasma H-2 for different time to create oxygen vacancies. The longer the treating time, the higher the concentration of oxygen vacancies. Meanwhile, the crystal structure and morphology of MnO2 material remain the same as the raw material after plasma H-2 treatment. The sample modified by plasma H-2 for 10 min (MnOx-10) exhibited a high specific capacitance of 296.9 F g(-1) at 0.5 A g(-1) and a superior cycling stability with a capacity retention of 90.0 % after 5000 cycles. Moreover, the asymmetric supercapacitor (ASC) using the as-prepared MnOx-10 as cathode and Kochen Black (KB) as anode was fabricated and showed an outstanding cyclic stability with a capacity retention of 90.0 % after 5000 cycles and a high energy density of 61 Wh kg(-1) at a corresponding power density of 750 W kg(-1). This study provided a comprehensive understanding of plasma H-2 as an effective technique for introducing oxygen vacancies and further broaden the application of manganese oxide as a kind of high capacity and low cost electrode materials.