化学组成对EMD电化学行为的影响

为了了解化学组成对电解二氧化锰(EMD)电化学行为的影响,分析了三种商品 EMD的组成,它们分别为Mn_0.881⁴⁺Mn_0.044³⁺O_1.655^2-(OH)_0.345^-、Mn_0.880⁴⁺Mn_0.048³⁺O_1.666^2-(OH)_0.334^-和 Mn_0.879⁴⁺Mn_0.054³⁺O_1.677^2-(OH)_0.322^-, X射线衍射表明晶型为γ-MnO₂.通过循环伏安、恒流放电、 电位-时间关系等实验研究其电化学行为,结果表明,EMD中结合水含量(即阳离子空位数) 增加时,样品开路电压升高、放电容量增大、第1电子还原的峰电位正移.

Influence of Composition on the Electrochemical Performance of EMD

Three electrolytic manganese dioxide (EMD) samples were characterized by XRD and chemical analyses. Their electrochemical performances were studied by cyclic voltametry, constant-current discharge, and choronopotentiometry. The results show that the three samples have the same structure, γ-MnO_2, but their combined water contents are different. The chemical compositions of the three samples can be formulated as A: Mn⁴⁺_0.881Mn³⁺_0.044O²-_1.655(OH)^-_0.345, B: Mn⁴⁺_0.880Mn³⁺_0.048O^2-_1.666(OH)__0.334 and C: Mn⁴⁺_0.879Mn³⁺_0.054O^2-_1.677(OH)^-_0.322. The electrochemical performances are influenced by the combined water contents, which are related to the number of cation-vacancy in the samples. The open circuit potential, the discharge capacity and the peak potential of one electron reduction increase with the increase of the combined water contents in the samples.