Disclosure of the internal mechanism during activating a proton exchange membrane fuel cell based on the three-step activation method

In our previous peer-reviewed article, a three-step method is put forward for increasing the efficiency of activating a newly-built membrane electrode assembly (MEA). By changing the activation temperatures of each step of the three-step method, the fuel cell performance can be greatly improved when compared with a normal one-step activation method. In this article, a deep understanding of the internal mechanism of this three-step method is conducted. Both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are tested after each I-V test round of a step. Two indexes, i.e., resistance reducing rate and effective current generation of catalyst (ECGC), are put forward. By integrating these two indexes, it clearly shows that the three-step activation method includes two effects, i.e., pore digging effect and pore swelling effect, which dominates in Step 1 and Step 2 separately. Finally, a pore forming mechanism model is put forward, which explains that the pore digging effect helps to form more three-phase reaction points and the pore swelling effect helps the three-phase points to become more effective. The same model also explains why the electrochemical surface area (ECSA) decreases during Step 1 and Step 2. (c) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

A three-step method is proposed to increase the efficiency of activating a newly-built MEA, showing improvements in fuel cell performance by changing activation temperatures. Through CV and EIS testing, two new indexes were introduced to analyze the internal mechanism of the activation method. It was found that the three-step activation method includes pore digging effect and pore swelling effect, which contribute differently in Step 1 and Step 2.