Study on the degradation mechanism of the frame for membrane electrode assembly in proton exchange membrane fuel cell.

The membrane electrode assembly (MEA) in the proton exchange membrane (PEM) fuel cell needs to be encapsulated by a frame to improve its assembly strength and sealing performance. However, irreversible degradation usually occurs to invalidate the frame and cause the fuel cell fail. In this study, a series of experiments are conducted to simulate operating environment in the fuel cell, and degradation mechanism of the frame is explored. Changes of tensile strength, peeling strength, shearing strength, and bending strength are adopted to evaluate the frame stability, and effects of temperature, water, and acid on these indexes are quantified. It is found that the peeling strength has the most significant decline, which is the primary failure form of the frame. Acid solution provides the main contribution to this failure. In acid solution, hydrogen ions and water molecules permeate the frame, resulting in rapid degradation and separation of the bonding interface. This study reveals the degradation process of the frame for the first time, and helps enhance our understanding of the frame failure. • Ex-situ accelerated experiment is designed to simulate the degradation process of frame after long time. • The mechanical strength of proton exchange membrane fuel cell's frame decreases rapidly due to operating conditions, and peel strength reduces the most significantly. • The bonding interface of frame generate cavitation under operating conditions, which cause peel strength reduce by 62.14%. • Cavitation is formed at bonding interface because of the water molecules' and protons' penetration through substrate layer of frame. • Compared with polyethylene terephthalate, polyethylene naphthalate can reduce the penetration. [ABSTRACT FROM AUTHOR]