Direct and environmentally benign synthesis of manganese oxide/graphene composites from graphite for electrochemical capacitors

• Published in: Journal of power sources 2015-05, Vol.281, p.44-48
• Main Authors: Lee, Hae-Min, Jeong, Gyoung Hwa, Kang, Doo Won, Kim, Sang-Wook, Kim, Chang-Koo
• Format: Article
• Language: English
• Subjects: Cycling stability; Electrochemical capacitor; Environmentally benign; Graphene; Manganese oxide; Specific capacitance
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2015.01.155

We develop a direct and environmentally benign method to prepare manganese oxide (Mn3O4)/graphene composites via one-step hydrothermal synthesis from graphite without using strong acids and toxic reducing agents. Structural and morphological analyses reveals that the irregularly shaped Mn3O4 nanoparticles are well-dispersed on the graphene flakes. Cyclic voltammetry and galvanostatic charge–discharge tests indicate that the charge-storing mechanism of the Mn3O4/graphene composites is pseudocapacitive. The Mn3O4/graphene composite exhibits a specific capacitance of 367 F/g at a current density of 5 A/g. After 3000 charge–discharge cycles, the Mn3O4/graphene electrode retains 91.8% of its initial specific capacitance. From electrochemical impedance spectra, it is evident that the changes in both the equivalent series resistance and charge-transfer resistance of the Mn3O4/graphene electrode before and after 3000 charge–discharge cycles are small, indicating good cycling and electrochemical stability of the Mn3O4/graphene electrode. •The Mn3O4/graphene composites were directly synthesized from graphite.•This method does not require the use of strong acids and toxic reducing agents.•The Mn3O4/graphene composite had a specific capacitance of 367 F/g.•The cycling and electrochemical stabilities of the Mn3O4/graphene were good.