PbO~2纳米粉体的固相合成及其对MnO~2电极材料的改性作用

利用固相氧化反应制备了PbO~2纳米粉体样品，借助XRD，TEM以及循环伏安测试对其性质进行了表征。同时，对反应条件的选择进行了讨论。将所得样品用于改性MnO~2电极，恒流放电测试结果表明，样品掺杂量在1.25%～5.00%间对MnO~2有良好的改性效果，可使改性MnO~2的放电容量得到极大提高。循环伏安测试结果表明，铅的掺入改变了MnO~2的放电机理。在循环扫描过程中，掺杂物与MnO~2均不再以单纯氧化物的形式存在，而是形成了一系列Pb(X)(X=0,Ⅱ)Mn(Y)(Y=Ⅳ，Ⅲ，Ⅱ)复合物的共氧化与共还原，抑制了电化学惰性物质Mn~3O~4的生成和积累，从而有望改善MnO~2的可充性能。纳米PbO~2与常粒径PbO~2与常粒径PbO~2(标记为S)对MnO~2的改性机理类似。但前者对MnO~2的改性效果明显优于后者，当恒流放电至-1.0V时，其放电容量较S样改性MnO~2的放电容量平均高出约30%。

Synthesis of nanophase PbO~2 by solid state reaction and its influence on MnO~2 electrode

Nanophase PbO~2 was prepared successfully by solid-phase redox reaction and characterized by XRD, TEM and CV techniques. The synthesis conditions of nanophase materials were discussed. PbO~2 modified MnO~2 electrodes were fabricated and their electrochemical properties were studied by means of constant current discharge and CV experiments. The results indicated that the optimum ratio of PbO~2 additives were 1.25%～5.00%. The charge-discharge mechanism of MnO~2 changed because the Pb(X)(X=0, Ⅱ) and Mn(Y)(Y=Ⅳ，Ⅲ，Ⅱ) atoms formed stable complexes. These complexes could be cooxidized and coreduced and thus restrained the formation of electrochemically inactive Mn~3O~4. The rechargeability of the MnO~2 electrode could be improved. Discharge mechanism of MnO~2 doped with nanophase sample was similar to that doped with conventional sample(S). But the nanophase sample was more effective in modifying MnO~2 electrode than the conventional sample. The discharge capacity of the nanophase PbO~2 modified MnO~2 electrodes were in average 30% higher than that of the conventional PbO~2 modified ones.