存水量对PEMFC零度以下储存性能衰减的影响

Effect of subzero storage on PEM fuel cell with different residual waters

通过模拟电池停车后以不同贮水量在-10℃保存,经历8次冰冻-解冻循环后,考察了其对电池性能,电化学特性的影响。当电池贮水量较小时,电池的性能衰减不明显,随着贮水量的增大电池的性能损失随之增大;通过对冰冻循环过程中电化学阻抗谱的测定发现在8次循环中电池的欧姆电阻都没有明显改变,但体现电荷转移电阻和电池内扩散电阻的高频圆弧半径随循环次数明显增加;从循环伏安测试结果可以看出催化剂的电化学活性表面积没有明显减小,因此推断电池性能衰减主要来自于催化层扩散阻力增大。

The amount of residual water in the fuel cell has great influence on the cell performance and electrochemical performance if the cell is subzero stored. To clarify,this effect eight times of subzero storage at -10 ℃ were carried out among four cells with different amounts of residual water. When the water amount was small there was almost no performance loss, as the water amount increasing the degradation became serious. The ohmic resistance did not change during the freeze cycles by measuring the electrochemical impedance spectra, but the polarization resistance reflected from the diameter of the higher frequency arc increased obviously when the water amount was large. Since the electrochemical active surface area did not change, so the degradation was mainly come from the diffusion resistance of the catalytic layer.