放电电流密度对DMFC交流阻抗的影响

测试了膜电极组件(MEA)在不同工作电流密度(J)下的交流阻抗谱,并用等效电路L1R1 (CR2) QR3(L2R4)]进行拟合.内阻变化最平缓,先减小,后略微增大,变化幅度小于初始值的10％；阴极法拉第阻抗随着电流密度的增大而减小,当J＞ 1.00 A/cm2时,产生的水膜导致三相界面减少后,该阻抗又增大；阳极反应...

Effect of discharge current density on alternating current impedance of DMFC

Alternating current(AC) impedance spectroscopy of membrane electrode assembly (MEA) under different discharge current densities(J) was tested and fitted by the equivalent circuit L1R1(CR2)QR3(L2R4)].The change of internal resistance was the gentlest,decreased firstly and then increased thinly,the change range was less than 10% of the initial value.The cathodic faradaic impedance decreased with the increasing of current density,when J>1.00 A/cm2 and water film was formed,leading the decrease of three phase interface,the impedance was increased.The change of anodic faradaic impedance was most pronounced,decreased suddenly with the increase of current density,proved that anodic reaction impedance was determined by overpotential.The overpotential increased constantly,the discharge current increased,leading the decrease of adsorbates on the surface of catalyst,making the cathodic double layer capacitor characteristic increased constantly,both faradaic impedance which characterized electrocatalysis performance of intermediates at anodic reaction and inductance which characterized relaxation phenomenon were reduced.