Seals and Sealants in PEM Fuel Cell Environments: Material, Design, and Durability Challenges

Abstract

Fuel cells have significant potential to improve energy utilization efficiency, but remain quite expensive due to the cost of key components, including the membrane of PEM fuel cells, the catalyst, and the bipolar plates. Due to the cost and significance of these items, extensive research has been devoted to reducing cost and improving the quality and performance of these components. By contrast, seals, sealants, and adhesives play a more mundane role in the overall performance of fuel cells, and yet the failure of these materials can lead to reduced system efficiency, system failure, or even safety concerns. Less attention has been given to the performance and durability of these products, yet as improvements in other fuel cell components are made, these seals are becoming a more critical link in the long term performance of fuel cells. This review paper highlights the importance and background of fuel cell seals; discusses the chemical, thermal, and mechanical environments to which fuel cell seals are subjected; and suggests design and testing protocol improvements that may lead to improved fuel cell system performance.

A review of polymer electrolyte membrane fuel cell durability test protocols

“…As new materials continue to be developed and new designs emerge, the need for relevant accelerated testing, as well as AST protocols, increases. However, as stated by Dillar et al [6], it is difficult at this time to propose an accelerated protocol without performing a detailed examination of the existing fuel cell performance and diagnostics data, such as ionic resistance, polarization curves, lifetime tests, fuel crossover rates, and effluent concentrations. Also, regardless of the accelerated protocol developed, care must be taken to perform accelerated testing under conditions that do not introduce new failure mechanisms that would be unrealistic in fuel cell environments.…”

Assessing the Tearing Energy of a Hydrocarbon Elastomeric Seal Material for Fuel Cell Applications

“…The possibility of an increase in crosslink density has been examined for this sealant using Tobolsky's method for monitoring both relaxed and momentary stiffness of molded seals [30]. Some increase in momentary stiffness was observed for samples aged in air at elevated temperatures 1 The error bars represent -1 standard deviation about a mean, all of which are based on means of three to five individual specimens. While fracture values within any given specimen were quite consistent.…”

“…Contact with coolant liquids is also possible in some designs. Seal failure modes in such conditions can include excessive relaxation that effectively reduces the seal contact forces to a point that leaks can occur, chemical degradation of seals that could allow resulting degradation products to contaminate the cell, and cracking or fissures that could result in loss of sealing integrity [1]. This paper focuses on this latter failure mode, examining the tearing resistance of a new hydrocarbon seal material over a…”

Study on interfacial leakage characteristics of rubber sealing under temperature cycle conditions in PEM fuel cell

“…The PEMFC uses a sealing structure to separate the fuel (hydrogen), air (reactant oxygen), and coolant and keep them in their respective flow channels. Any leakage can lead to a decrease in system efficiency, weaken system reliability, and potentially present safety risks [6][7][8][9]. Leakage behavior has been found to play an important role in improving fuel efficiency and reducing pollution levels [10].…”