酸化剂中H_2SO_4含量对PBI燃料电池性能的影响

Effects of H_2SO_4 Content in Acidifier on Performance of PBI Fuel Cell

目的探究高温酸化时在酸化剂中加入不同含量的H2SO4对PBI膜和高温燃料电池电极的影响.方法质子交换膜是高温质子交换膜(HT-PEM)燃料电池的核心部件,对燃料电池的性能起到主导作用.笔者制备了酸化剂中掺杂不同量H2SO4的PBI膜,测试了高温PBI燃料电池的I-V特性和交流阻抗特性,对比了PBI膜表面SEM照片的差异,分析了高温PBI膜掺杂硫酸的含量和电池温度对高温燃料电池性能的影响.结果研究发现:高温PEM燃料电池的PBI膜在高温酸化时及高温燃料电池运行时,H2SO4的强氧化性起主导作用,破坏了PBI膜的内部结构,阻碍了质子的传递,对PBI膜和燃料电池电极均有损伤.结论酸化剂中掺杂强电解质强氧化性的H2SO4不利于高温PBI膜燃料电池性能的提高,虽然常温下经H2SO4处理后的PBI膜的电导率能够显著提高,但高温运行的PBI膜燃料电池的性能有明显下降.H2SO4的加入对PBI膜的电导率没有明显的提升,反而对高温燃料电池的性能有所抑制.掺杂强电解质H2SO4对提升电池性能是不合适的.

The purpose of this paper is to explore the effects of different contents of H2 SO4 in acid- ifying agent on PBI membrane and high temperature fuel cell electrode under the high-temperature acidification condition. Proton exchange membrane is one of the core parts of high temperatureproton exchange membrane（HT-PEM） fuel cells. It plays a very important role for fuel cell＇s performance. The authors prepared PBI membranes doped with the acidifier by adding different contents of sulfuric acid and tested I-V characteristics and AC impedances of the high temperature PBI membrane fuel cells. The surface differences of the doped PBI membranes were observed with the SEM images, and effects of the doped content of sulfuric acid and the cell temperature on perform- ances of HT-PEM fuel cell were analyzed. It is observed that when PBI membrane of HT-PEM fu- el cell is acidized at high temperature and when the fuel cell works under high temperature condi- tion, the strong oxidizing of H2SO4 plays a leading role, which destroys the internal structure of PBI membrane, hinders transfer of proton, damages PBI membrane and the fuel cell electrode. Conclusion is that although the electrical conductivity of PBI membrane under normal temperature is significantly enhanced after treatment of H2SO4 but the performance of PBI membrane fuel cell is clearly decreased under high temperature. The acidulant which mixed with strong electrolyte and oxidizing H2 SO4 is unfavorable to improve the performance of the high temperature PBI membrane fuel cell.