采用交流阻抗法对质子交换膜燃料电池(PEMFC)电化学行为的研究

通过对PEMFC运行于不同状态下的交流阻抗分析,提出其等效电路可用LR₁[QR₂]表示.对各参数模拟表明,随放电电位升高感抗L下降,而系统电阻R₁和电荷转移阻抗R₂均呈上升趋势,改进催化层结构设计及在大电流运行时加大排水量有利于减小电池内部感抗;加湿温度上升有利于降低R₁和R₂,但低放电电位下R₂的偏离程度较大,电池内阻是LR₁[QR₂]的综合结果,在高放电电位时,随加湿温度上升内阻下降,低放电电位时内阻上升的原因在于水抑制了反应气体到达催化剂表面及电荷内部转移的过程,使电池内部趋向于电容状态.LR₁[QR₂]微观分析和宏观现象得到较好的统一,高放电电位时表现尤为明显.

Studies on the Electrochemical Behavior of Polymer Electrolyte Membrane Fuel Cell (PEMFC) by AC Impedance Method

Based on AC impedance analysis of polymer electrolyte membrane fuel cell(PEMFC) in different states, it is proposed that LR 1 can be used to represents its equivalent circuit. The simulation result for LR 1 shows that, with the discharge voltage decreasing at various humidification temperatures, inductance L decreases whereas system resistance R 1 and charge transfer resistance R 2 increase. Moreover, it is beneficial to decrease inductance by improving catalyst layer and increasing the amount of drainage. Higher humidification temperature decreases R 1 and R 2, though at lower discharge voltage R 2 has a large deviance. In a word, the synthesis of LR 1 is the internal resistance, which drops at a higher discharge voltage with the humidification temperature arising. The reason for internal resistance decreasing at a lower discharge voltage is that, water prevents both processes of reaction gas from attaining catalyst and the charge transferring, which makes internal cell under capacitance state. The microanalysis agrees with the macro-phenomena, particularly at a higher discharge voltage.