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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.