Performance and Durability of Proton Exchange Membrane Vapor-Fed Unitized Regenerative Fuel Cells

Fornaciari, Julie C, Garg, Samay, Peng, Xiong, Regmi, Yagya N, Weber, Adam Zev and Danilovic, Nemanja (2022) Performance and Durability of Proton Exchange Membrane Vapor-Fed Unitized Regenerative Fuel Cells. Journal of Electrochemical Society, 169 (5). 054514-054514. ISSN 0013-4651

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Abstract

With growing demand on electricity, clean hydrogen production and usage can be an asset not only to mitigate emissions, but also for long-term energy storage. Hydrogen gas, a high-density energy carrier, can be made through electrolysis in charging mode and generate electricity via a fuel cell in discharging mode in a unitized regenerative fuel cell (URFC). While URFCs reduce cost by combining charging and discharging modes in a singular device, switching between modes becomes burdensome, and water management is a major challenge. One way to mitigate these issues is to operate the entire system in the vapor phase. Vapor-phase operation simplifies the physics of the system, but introduces losses within the system, primarily ohmic and mass transport during the charging mode. Here, we explore the performance of a proton exchange membrane (PEM)-URFC under vapor-phase conditions and the impact of different PEMs, feed gases, and relative humidity on performance and durability. By tailoring operating conditions and membrane, the vapor-URFC achieves a roundtrip efficiency of 42% and a lifetime of 50,000 accelerated stress test cycles for fully humidified feeds. Discussion of vapor-URFC for energy storage and extensions to look at various applications shows the promise of this technology.