Mn3O4 for supercapacitors was prepared by hydrothermal method at different reaction temperature and certain reaction time. Y doped and composite graphene were realized. The morph-ology, structure and electrochemical properties of the samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical workstation. The standard PDF cards 89-4837 are identical and the single phase Mn3O4 belongs to tetragonal system. The space group is I41/amd (No. 141). The

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... ared Mn3O4 is rod like particle. The specific capacitance of Y-Mn3O4 and Y-Mn3O4/graphene composites can reach 89 F·g-1 and 267 F·g-1 when Y content is 5%. The cyclic voltammetry curves of Y-Mn3O4/graphene composites are rectangular, indicating that Y doped and graphene loading synergistically improve the electrochemical performance of Mn3O4.