Abstract:

High temperature proton exchange membrane fuel cell (HT-PEMFC) has broad application prospect, but it is limited by the short lifespan. In this paper, the stability of a hundred-watt air-cooled HT-PEMFC stack was studied. The constant current test showed that the voltage decay rate of the single cell in the middle of the stack was 5—10 times that at the two ends. XRD and TEM results showed that the Pt particle size of the single-cell catalyst at different positions varies slightly, while the acid absorption titration of the electrode plate and the ohmic polarization loss analysis showed that the phosphoric acid loss rate of the single-cell catalyst in the middle position was about 2—3 times that at the two ends, causing its internal resistance to be 5—8 times that of the two ends. Meanwhile, the migration of phosphoric acid from the membrane to the electrode resulted in an increase of 41—102mV in the oxygen gain voltage compared to the two ends. To sum up, the excessive loss of phosphoric acid from the single cell in the middle of the stack is the main reason for its short life, which is the result of the uneven temperature distribution inside the stack. Therefore, the key to increase the stack life is to optimize the management of phosphoric acid and heat in the stack.

Key words: HT-PEMFC, degradation, long-term test, acid leaching

摘要：

高温质子交换膜燃料电池（HT-PEMFC）应用前景广阔，但是目前HT-PEMFC电堆寿命较短。为此，本文对一个百瓦级空冷HT-PEMFC电堆的稳定性进行了研究。恒电流测试结果发现电堆中间位置单电池电压的衰减速率是两端的5～10倍。XRD、TEM测试结果表明电堆不同位置单电池催化剂Pt粒径变化较小，而极板吸酸量滴定与欧姆极化损失分析结果表明中间位置单电池磷酸流失速率是两端的2～3倍，导致其内阻是两端的5～8倍，膜中磷酸的流失迁移至电极导致氧增益电压比两端增加41～102mV。综上，电堆中间位置单电池磷酸流失过快是导致电堆寿命缩短的主要原因，而电堆温度分布不均则是磷酸流失过快的主要原因。因此，若要提高电堆的寿命，关键要从电堆磷酸与热的管理方面进行优化。

关键词: 高温质子交换膜燃料电池, 衰减, 耐久性测试, 酸流失