纳米β-PbO_2的制备及其对MnO_2电极的改性

Preparation of nanosize β-PbO_2 and its doping modification to MnO_2 electrodes

采用化学法制备纳米β-PbO2对MnO2电极进行掺杂改性。X射线衍射光谱法(XRD)、透射电子显微镜法(TEM)分析表征结果表明,以含Pb2+的偏酸性溶液[Pb(NO3)2水溶液或Pb(Ac)2水溶液]为铅源,以过量的高浓度碱性NaClO溶液为氧化剂,在5～10℃强力搅拌反应2h生成可溶性铅酸盐溶液,再加稀硝酸将溶液pH值调低至7.0左右即可制得粒径30nm左右、晶型完整的β-PbO2粒子。对用纳米β-PbO2掺杂改性的MnO2电极进行放电性能测试的结果表明,将5%～10%的纳米β-PbO2掺入到MnO2中制成的掺杂电极的放电容量较纯MnO2电极可提高60%以上,放电过程电位升高200mV以上。循环伏安测试结果表明,β-PbO2与MnO2的放电产物形成复合产物,改变了反应历程,在一定程度上抑制了电化学惰性物质Mn3O4的生成和积累,从而使MnO2电极的可逆性得到了改善。

The preparation of nano-β-PbO2 and its doping modification to MnO2 electrodes were studied. The preparation procedure was as follows： Pb（NO3）2 or Pb（Ac）2solutions was used as lead source and alkaline NaCIO was used as oxidant. After agitating at 5-10 ℃ for 2 h, followed by adjusting pH to around 7.0, the product of β-PbO2 particles was obtained. XRD and TEM examinations show that the β-PbO2 particles have complete crystal-type and grain size of 30 nm. The modified MnO2 electrodes were fabricated by doping the prepared nanosize /3-PbO2 to MnO2 and their electrochemical properties were studied by constant current discharge and CV testing. The constant current discharge result shows that when 5%--10% β-PbO2 is added, the nanosize β-PbO2 modified MnO2 electrodes provide around 200 mV discharge voltage and 60% discharge capacity higher than that of pure manganese dioxide electrodes. The result of CV indicates that the reaction mechanism is changed through interaction of β-PbO2 and MnO2 so that the formation of electrochemically inactive Mn3O4 is restrained and the reversibility of the MnO2 electrode is improved.