低湿度下质子交换膜燃料电池的交流阻抗分析

采用Nafion(112膜制备膜电极(MEA)并对质子交换膜燃料电池(PEMFC)进行了无外增湿条件下E-I极化曲线和电化学交流阻抗谱(EIS)的测试。对比分析了20和55℃时的交流阻抗谱图,结果表明不同温度下EIS中代表质子传导电阻的Rhf值和电荷转移电阻的Rct值有明显不同,低电流密度下的Rhf值和E-I极化曲线上的欧姆极化区具有更好的一致性。电池在15 mA.cm-2的恒电流密度下放电时,随着温度升高Rhf值和Rct值都相继增大,其中Rhf值随温度升高有显著变化,是导致PEMFC在操作温度超过45℃时性能降低的主要因素。

Analysis of AC Impedance in PEMFC under Low Humidity

The membrane electrode assembly (MEA) was constructed with Nafion 112 membrane. The E-I polarization curves and the electrochemical impedance spectrum (EIS) of the proton exchange membrane fuel cell (PEMFC) without external humidification were tested. By comparing with the EIS at 20 ℃ and 55 ℃， the test results indicated that there were obvious difference between R_hf,which represented the ionic resistance, and R_ct, which corresponded to the charge transfer resistance at these two different temperatures. The values of R_hf under low current densities were consistent with the ohmic loss in PEMFC. The values of R_hf and R_ct increased with the increasing of the operating temperature when PEMFC was operated at 15 mA·cm^-2. The value of R_hf changed significantly with the increasing of temperature, which was the main factor that caused the breakdown of PEMFC operating over 45 ℃.