氢气和空气中的氯离子杂质对燃料电池催化层的影响
Chloride contamination effects on proton exchange membrane fuel cell performance and durability

Hui Li
Haijiang Wang
Weimin Qian
Shengsheng Zhang
Silvia Wessel
Tommy T．H．Cheng
Jun Shen
Shaohong Wu

Abstract

Chlorine is a major fuel contaminant when by－product hydrogen from the chlor－alkali industry is used as the fuel for proton exchange membrane （PEM） fuel cells． Understanding the effects of chlorine contamination on fuel cell performance and durability is essential to address fuel cell applications for the automotive and stationary markets． This paper reports our findings of chloride contamination effects on PEM fuel cell performance and durability， as our first step in understanding the effects of chlorine contamination．

Fuel cell contamination tests were conducted by injecting ppm levels of contaminant into the fuel cell from either the fuel stream or the air stream． In situ and ex situ diagnosis were performed to investigate the contamination mechanisms． The results show that cell voltage during chloride contamination is characterized by an initial sudden drop followed by a plateau， regardless of which side the contaminant is introduced into the fuel cell． The drop in cell performance is predominantly due to increased cathode charge transfer resistance as a result of electrochemical catalyst surface area （ECSA） loss attributable to the blocking of active sites by Cl− and enhanced Pt dissolution．

氢气侧的杂质氯气会转化为盐酸

实验装置

污染物使电压迅速下降，需要控制在1ppm以下。

对0．75A／cm2以上影响巨大。

对空气侧的影响也很大

氢气侧20ppm 1．0A／cm2再生困难

空气侧4ppm 0．75A／cm2可以一定程度再生

对开路电压的影响

对阻抗的影响

对催化剂ECSA峰的影响和双电层的影响

导入1ppm Cl－对空气侧催化剂影响更大，无论从哪一侧导入。

促进了铂催化剂的长大

氯残留在两侧催化层中

Conclusions

The presence of trace levels of Cl2 has been identified as an
impurity in the waste hydrogen produced from the chloro－alkaline
industry that could potentially be used as a fuel for PEM fuel cells．
The effects of Cl2 on PEM fuel cell performance and durability were
studied by separately injecting solutions of various HCl concentrations
into the fuel stream and the air stream．When Cl− was present
in either the fuel stream or the air stream， the cell performance
measured by cell voltage at a constant current density was characterized by an initial sudden decline， followed by a steady－state
drop （plateau）． The severity of the contamination effect was found
to be independent of the injection side but to increase with both
current density and HCl concentration．

Preliminary recovery tests revealed that cell performance was
non－recoverable in some cases， such as with high Cl− concentrations，
but partially recoverable with a low level of Cl−． More work
is needed to study recoverability after Cl− contamination．

EIS measurements indicated that contamination resulted in an
increase in both the charge transfer and mass transfer resistances
on the cathode side， but the increase in kinetic resistance was
the dominant contributor to the cell performance loss． Regardless
of the injection side， the presence of Cl− caused a more significant
decrease in cathode ECSA than anode ECSA． The reduction in
ECSA was explained as the result of both the site－blocking effect of
specifically adsorbed Cl− on the Pt surface and the enhancement
of Pt dissolution by the electrochemical formation of chloride complexes． The EOT cathode Pt crystallite size， determined by XRD， was
found to increase with Cl− concentration irrespective of injection
in the fuel or air streams．

This research is important for understanding the contamination
mechanism of chlorine and its effect on fuel cell performance
and the development of mitigation strategies to handle fuel cell contamination if waste hydrogen produced by the chloro－alkali
industry is to be used as fuel for PEM fuel cells．

因此国标中对氢气中氯等卤素粒子有明确的含量要求

海洋周边空气中氯离子含量大致0．005－0．13mg／m3这个级别，累计起来是否有影响？不做处理是否涉及维修维护？