Assembly Of Mn₃O₄ Composites And Their Supercapacitor Properties

Supercapacitors, also known as electrochemical capacitors or gold capacitors, are new type of energy storage devices. The supercapacitors have advantages such as environmental friendship, larger cycle life and much higher power density. Supercapacitor is promising to become the key part of electric vehicles and communication devices. Since the quality of electrode is crucial to the performance of supercapacitor, so the research focus of supercapacitor is to synthesis better electrode which leads to higher power density and longer life cycle.In recent years, Mn3O4 is also considered as supercapacitor electrode material, due to its stable morphology and controllable microstructure. Compared with Mn O2, Mn3O4 has much superior, such as uniform structure, stable performance and easily obtain pristine phase Mn3O4 Compared with graphene, carbon black(CB) used in industrial production has merits of low price and environment friendly. Moreover, it has been widely used in supercapacitor electrode and lithium-ion batteries as a conductive additiveIn this work, a series of Mn3O4/carbon black composite(Mn3O4/CB) is synthesized by a chemical synthesis method directly on the surface of carbon black. The TEM and XRD were used to define the surface morphology. The electrochemical performance of electrode materials was measured by voltammetry and galvanostatic charge-discharge methods. The electrochemical properties revealed from the rectangularity of the cyclic-voltammogram loops of the composite electrode are excellent. These results indicate the almost-ideal capacitive behavior of the Mn3O4/CB composite. The electrochemical tests indicate that the specific capacitance of the Mn3O4/CB composites reaches 720 F/g at the current density of 0.1 A/g in 2 M Na2SO4 solution, which is approximately 4.36 times than that of the pristine Mn3O4(165 F/g). The Mn3O4/CB composite electrode shows excellent capacity retention(91.6%) after 5000 cycles at the current density of 30 A/g.Mn3O4/G/CB composite is formed which improved the performance of Mn3O4 by adding a certain amount of graphene and carbon black. The research of Mn3O4/G/CB composite was conducted with varies mass ratios of graphene and carbon black. The optimum specific capacitance(0.1A/g,661F/g) and cycling stability(69.2% retain over 5000 cycles at a high current density of 30A/g) were found while the mass ratio of graphene and carbon black is 2:1.As discussed above, we conclude that the specific capacitance and cycling stability of Mn3O4 can be significantly improved by adding carbon black solely.