Development of Chemical and Mechanical Acceleration Stress Test Method for PEMFC Polymer Membranes

Abstract

To improve the durability of polymer electrolyte membrane fuel cell polymer membranes, it is important to evaluate their durability in a short time. In 2016, the U.S. Department of Energy (DOE) presented the AST protocol, a degradation method that simultaneously performs electrochemical and mechanical degradation. The AST protocol has several problems such as long evaluation time, electrode degradation due to open circuit voltage changes, and difficulty in determining whether the durability of the polymer membrane is electrochemically or mechanically weaker. Based on the DOE accelerated stress test protocol, we supplied O₂ instead of air to the cathode, increased the drying time, distinguished and improved electrochemical/mechanical evaluation methods. The improved AST protocol reduced the evaluation time of the Nafion XL membrane electrode assembly by approximately 3 times or more, and the degradation of the electrode catalyst was also reduced by 1/3. In addition, it was confirmed that the polymer membrane exhibited weaker mechanical durability than electrochemical; hence, it was possible to ascertain the cause of the degradation, such that the durability of the polymer membrane can be evaluated more accurately.