碳包覆改性二氧化锰电极材料的制备和性能

Preparation and Properties of Carbon Coated Manganese Dioxide Electrode Materials

先以高锰酸钾(KMnO4)和硫酸锰(MnSO4·H2O)为原料用电脉冲辅助氧化还原法制备二氧化锰(MnO2)粉末,再以葡萄糖(C6H(12)O6)为碳源用液相烧结法制备出不同碳包覆量的MnO2/C复合材料,研究了碳包覆量对材料的形貌、结构和电化学性能的影响。结果表明,碳的加入使MnO2晶型由γ型转变为α型,葡萄糖加热分解后生成无定型的碳覆着在二氧化锰颗粒的表面,抑制了晶粒生长而使晶粒细化。充放电测试结果表明,在葡萄糖浓度为1.5g/L、电流密度为2 A·g^-1条件下二氧化锰的比电容为722.2 F·g^(-1)。与包覆二氧化锰前比较,包覆后比电容提高了64.6%。经过4000圈充放电循环后电容保持率为74.72%,表现出良好的电容特性和循环性能。

Manganese dioxide powders were firstly prepared via electric pulse assisted redox method with KMnO4 and MnSO4 as raw material, then MnO2/C composite materials coated with different amounts of carbon were fabricated via liquid phase sintering with glucose as a carbon source. The effect of amount of coated carbon on the morphology, structure and electrochemical properties of the MnO2/C materials were investigated. Results show that the coated carbon could induce the transformation of crystallographic structure of MnO2 from γ-type into α-type. Under heating conditions glucose decomposed and coated on the surface of MnO2 particles, which could inhibit the grain growth and thus refine grains. When the preparation with the process parameters: glucose concentration was 1.5 g/L and the current density was 2 A·g^-1, the prepared MnO2/C material presented the specific capacitance of MnO2 of 722.2 F·g^-1, in other words, the carbon coating could increase the specific capacitance by 80%, in comparison with that of the blank ones. Furthermore, after 4000 charge-discharge cycles, the capacitance retention rate could still maintain 74.72%, displayed good electrochemical performance and cycling performance.