Manganese Oxides Preparation And Their Properties As Electrode Material Of Supercapacitor

Supercapacitors also known as electrochemical capacitors is a new type of energy storage device between the battery and the conventional electrostatic capacitor. Compared with battery,Supercapacitor has a larger power density value,and has a large current discharge,charging is completed in a short time,high charge and discharge efficiency,long cycle life characteristics.Compared with the conventional electrostatic capacitor,supercapacitor has a higher capacitance.Research supercapacitors restructuring of China’s energy future,new energy development and utilization has profound theoretical and practical significance.Performance of the electrode material is super good or bad performance capacitance crucial factor.In this paper, an inexpensive electrode material manganese oxides as supercapacitor,the morphology and capacitance characteristics of manganese oxide was prepared by different methods.Four different methods for preparing the manganese oxide electrode materials:MnO2(a)、MnO2(b)、MnO2(c)�'� Mn3O4(d).Using electrochemical testing such as:CV, EIS,Constant current charge-discharge and Cycle performance.Using physical testing such as:XRD,SEM,TEM to investigate the structure,surface morphology and supercapacitor performance.After a series of comparison,to find out the best method:MnO2(a) is prepared by MnCl2 and KMnO4.Study found that in four of the manganese oxide prepared by very different morphology,200-300 nm spherical structure of MnO2(a) is a thin layer of MnO2 grow out,MnO2(b) is grow out thicker sheet MnO2 spherical structure,MnO2(c) to a particle size of 5-8 nm granular structure,Mn3O4(d) is a diameter of 5-10 nm,length of 200-500 nm,the sphere is about 2 um composed of rod-like crystals.Four electrode materials are prepared out,the specific capacitance of MnO2(a)、MnO2(b)、MnO2(c)�'� Mn3O4(d) are 203.0、159.9、173.5 �'� 137.5 F g-1,charge-discharge efficiency are 97.7%、89.8%、64.9%�'� 63.7%.Charge transfer resistance are 0.76、1.42、1.05 �'� 1.75Ω.Experimental results show that compared four kinds of the manganese oxide electrode material.Electrode material MnO2(a) as a supercapacitor has the best reversible and capacitance characteristics.In preparation of MnO2(a),reaction concentration,reaction temperature,reactiontime,the reaction was added sequentially,heat treatment temperature,Carbon materials, etc.Optimum conditions is KMnO4 / MnCl2 molar ratio of 2:3,the reaction concentration of 0.3 mol L-1 MnCl2 solution and 0.2 mol L-1 KMnO4 solution,the reaction temperature is 60℃,the teaction time is 6 h,reactants are added to the order before adding MnCl2 solution plus KMnO4 solution.Optimum heat treatment temperature is 80℃.Preferred carbon material is activated carbon.