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Oxygen vacancies modulation in graphene/MnOx composite for high performance supercapacitors
- Yue, Jiasheng, Lu, Gang, Zhang, Pian, Wu, Yunhao, Cheng, Zhiming, Kang, Xiaohong
- Colloids and surfaces 2019
- air, capacitance, electrodes, energy, graphene, graphene oxide, heat treatment, manganese dioxide, oxygen, phase transition, redox reactions
- An efficient and scalable method to improve the capacitive properties of MnO2 is reported by inducing graphene (rGO) and oxygen vacancies via a thermal treatment in air, in which graphene oxide (GO) is in situ reduced and graphene/MnOx (rGO/MnOx) composite without oxygen vacancies-induced phase transformation is formed. RGO/MnOx composite exhibits a large specific capacitance (274 F g-1 at 0.5 A g-1), excellent cycling stability (98.8% after 5000 cycles at 1 A g-1) and rate performance (171 F g-1 at 10 A g-1). The performance improvement of rGO/MnOx sample is mainly attributed to the moderate concentration of oxygen vacancies, rGO and special 3D porous architecture, which facilitate the rapid ionic and electronic transport and promote a facile redox reaction and surface double-layer capacitance. The asymmetric supercapacitor composed of rGO/MnOx//Kochen Black (KB) also shows an outstanding cyclic stability (89% after 5000 cycles) in all-solid-state asymmetric supercapacitor. The design and synthesis method of rGO/MnOx sample offers a promising approach to broaden MnO2-based electrode materials for a new-generation energy storage device.