This comprehensive review explores recent developments in Proton Exchange Membrane Fuel Cells (PEMFCs) and evaluates their alignment with the ambitious targets established by the U.S. Department of Energy (DOE). Notable advancements have been made in developing catalysts, membrane technology advancements, gas diffusion layers (GDLs), and enhancements in bipolar plates. Notable findings include using carbon nanotubes and graphene oxide in membranes, leading to substantial performance enhancements. Innovative coatings and materials for bipolar plates have demonstrated improved corrosion resistance and reduced interfacial contact resistance, approaching DOE targets. Nevertheless, the persistent trade-off between durability and cost remains a formidable challenge. Extending fuel cell lifetimes to DOE standards often necessitates higher catalyst loadings, conflicting with cost reduction objectives. Despite substantial advancements, the ultimate DOE goals of USD 30/kW for fuel cell electric vehicles (FCEVs) and USD 600,000 for fuel cell electric buses (FCEBs) remain elusive. This review underscores the necessity for continuous research and innovation, emphasizing the importance of collaborative efforts among academia, industry, and government agencies to overcome the remaining technical barriers.

Effective thermal management strategy for the polymer electrolyte membrane fuel cell (PEMFC) stack is critical in maintaining the overall stack efficiency and durability. The present assessment critically explores the recent developments (predominantly last decade) in thermal management strategies of PEMFCs, which encompasses an in-depth analysis of the thermodynamics, corresponding effects on components of PEMFC and the waste heat recovery system. In general, the operating temperature range of a PEMFC is 60–80°C. Entropy consequence and irreversible transport mechanisms of the reactants are the major contributions to heat generation. Air cooling is employed for compact stacks of less than 5 kW and water cooling is favored for stacks greater than 5 kW. Cooling using nanofluids enables better cooling efficiency than water while downsizing the size and weight of the system. Phase change cooling strategy to attain greater heat removal capacity is broadly employed for stacks greater than 10 kW, which is beneficial in a compact size of the cooling system contrasted to the water cooling system. Passive cooling methods employing vapor chamber, heat pipes and heat spreaders used were another cooling system for stack power ranges between 5 and 10 kW which have the benefit of reduced parasitic losses. In addition to thermal management strategies, integral challenges associated with each thermal management strategy is identified. Discussion on cold start thermal management of fuel cell electric vehicles was provided. Finally, the waste heat recovery system of energy efficiency and overall future prospectus for the betterment of thermal management of PEMFC is emphasized.

Direct methanol fuel cells (DMFC) are typically a subset of polymer electrolyte membrane fuel cells (PEMFC) that possess benefits such as fuel flexibility, reduction in plant balance, and benign operation. Due to their benefits, DMFCs could play a substantial role in the future, specifically in replacing Li-ion batteries for portable and military applications. However, the critical concern with DMFCs is the degradation and inadequate reliability that affect the overall value chain and can potentially impede the commercialization of DMFCs. As a consequence, a reliability assessment can provide more insight into a DMFC component’s attributes. The membrane electrode assembly (MEA) is the integral component of the DMFC stack. A comprehensive understanding of its functional attributes and degradation mechanism plays a significant role in its commercialization. The methanol crossover through the membrane, carbon monoxide poisoning, high anode polarization by methanol oxidation, and operating parameters such as temperature, humidity, and others are significant contributions to MEA degradation. In addition, inadequate reliability of the MEA impacts the failure mechanism of DMFC, resulting in poor efficiency. Consequently, this paper provides a comprehensive assessment of several factors leading to the MEA degradation mechanism in order to develop a holistic understanding.