碳粉表面自由能对空气电极成膜的影响

Effect of carbon surface free energy on the membrane forming of air electrode

在粉末接触角测试的基础上,用Wu方程估算了硝酸氧化或肼还原前后,活性炭和乙炔黑的表面自由能(简称表面能)。活性炭的表面能及其色散、极性分量分别为27.01 mJ/m2、1.93 mJ/m2和25.07 mJ/m2,硝酸氧化对活性炭表面能及分量的影响不大,而肼还原可使色散分量增加420%,极性分量降低30%;乙炔黑的表面能及色散、极性分量分别为25.24mJ/m2、10.77 mJ/m2和14.47 mJ/m2,用硝酸或肼处理,对色散分量影响较小,但两者均引起极性分量增加,分别为96%和67%。碳粉表面能的色散分量增加及极性分量降低,都将增加碳粉与PTFE之间的粘附功,有利于空气电极薄膜化。

On the basis of powder contact angle measurement, the surface free energy of active carbon and acetylene black before and after oxidized by nitric acid or reduced by hydrazine was estimated by means of Wu formula. Surface free energy, dispersion component and polarity component of active carbon were 27.01 mJ/m^2, 1.93 mJ/m^2 and 25.07 mJ/m^2, respectively. There were few changes on the components and surface free energy of active carbon after oxidized by nitric acid, while the dispersion component increased by 420% and the polarity component decreased by 30% after reduced by hydrazine. Surface free energy, dispersion component and polarity component of acetylene black were 25.24 mJ/m^2, 10.77 mJ/m^2 and 14.47 mJ/m^2, respectively. Treated with nitric acid or hydrazine, the polarity component of acetylene black increased by 96% or 67%, but had little influence on the dispersion component. Adhesive work between carbon powder and PTFE was increased either by increasing the dispersion component or decreasing the polarity component of surface free energy of carbon powder, which was helpful to achieve thinner air electrode.