Preparation And Electrochemical Performance Of Manganese Oxide/Carbon Composites

As a kind of supercapacitor materials, manganese oxide has high theoretical specific capacitance. But its poor electrical conductivity and the dissolution of active materials in the process of electrochemical cycles, manganese oxide restricted wide application as a supercapacitor material. With the help of high electrical conductivity, large specific surface area and pore volume of carbon, manganese oxide and carbon composite can effectively improve the poor conductivity of manganese oxide, in turn, markedly enhance the electrochemical performance of electrode materials.As a result, if we get the Mn O/C composites with the best electrochemical performance, the experiment should choose manganese carbonate as a manganese source, ascorbic acid as carbon source, with the mixing way of sand grinding and the next 6 hours of high temperature heat treatment at 700 oC.When current density is 1 A/g, the materials show the specific capacitance up to 807 F/g. Simultaneously, the Mn Ox/C electrode can maintain 76% of the initial capacity after 2500 cycles. When the current density increases to 10 A/g, the specific capacitance is 418 F/g, and the composites still show an outstanding performance.In the process of electrochemical cycles, manganese monoxide changes is converted into manganese oxide, with the morphology variety from the manganese monoxide manganese oxide embedded into carbon array to the three dimensional porous network structure consisting of manganese oxide/carbon composite sheets. The reason is that the small amount of dissolved Mn2+ transforms granular into thin sheets by nucleation and epitaxial growth, and these chips are well attached to the manganese oxide/carbon composite structures. Carbon effectively improves manganese oxide poor electrical conductivity, meanwhile, increase the specific surface area and pore volume of electrode materials. These inner interconnected holes provide continuous channel for the spread of the electrolyte ions to make much easier to reach the surface of the active materials, thus the electrochemical properties of the samples is improved.