Pb添加剂对MnO_2/C空气电极性能的影响

Effect of Pb addtives on MnO_2/C air electrode

为了提高MnO2的对氧气还原的催化活性,将硝酸锰和醋酸铅溶液浸渍到活性炭中,并在290℃下煅烧,制得氧电极催化剂,通过冷压方法制成气体扩散电极。用稳态极化测试了各个空气电极的电化学性能,结果表明醋酸铅添加7.5%时空气电极极化最小,在一般金属-空气电池的工作电流密度20～50mA/cm2下,电位比单独MnO2催化剂可提升30～50mV,并且随着电流密度的增加,电位提升更加显著。采用交流阻抗测试了空气电极的阻抗特性,通过分析对阻抗图谱采用两个Nerstian阻抗的等效电路进行了拟和,得到相关动力学数据。数据显示添加醋酸铅,减小了电化学极化阻抗和氧气扩散阻抗,提高了MnO2对氧气还原的催化活性。

In order to improve the electrocatalystic performance of MnO2, catalyst was prepared from the carbon black impregnated with Mn(NO3)2 and Pb(CH3COO)2,and heated at 290 ℃. The gas diffusion electrode was obtained by cold-pressing. Electrochemical performances of the electrodes were studied by current-potential polarization curves. The result showed adding 7.5% content of Pb(CH3COO)2 can gain optimal performance, the polarization is the smallest,at the typical current density 20-50 mA/cm2 of air-metal battery, air electrode potential can be improved by 30-50 mV. AC impedance properties of air electrode adding Pb(CH3COO)2 were invistigated. The impedance spectra were analyzed using an equivalent circuit containing two Nerstain diffusion terms, the simulated data were also discussed. The Pb(CH3COO)2 addtives can decrease the charge transfer resistance and oxygen diffusion resistance.