Mass and charge transport phenomena in porous transport layer for proton exchange membrane water electrolyzers: A review
S. Roohan Farooq Lala, Samaneh Shahgaldi
Abstract
Proton exchange membrane (PEM) water electrolysis offers a promising method for green hydrogen production, utilizing renewable sources and generating oxygen without carbon emissions, making it highly energy-efficient theoretically, and environmentally friendly. However, the global hydrogen production from water electrolysis is limited to ∼4 % only, due to the high cost of hydrogen production (USD 3–7/ kg) arising from the lower efficiency of the electrolyzers operated especially at higher current densities. PEM water electrolysis efficiency loss is primarily associated with mass and charge transport resistances at the interface of the porous transport layer (PTL), catalyst layer, and bipolar plates. These losses increase the voltage requirements for the PEM water electrolysis and increase the cost of hydrogen produced. PTL is an important component of PEM water electrolyzer which facilitates uniform gas distribution, and efficient electrolyte management, provides mechanical support, and ensures efficient thermal management by dissipating excess heat. The efficiency of a PEM water electrolyzer is directly dependent on different transport processes occurring through the cross-section and on the surface of PTL. Hence improving and controlling the transport processes in PTL is of paramount importance. This review compiles the current knowledge describing the mass and charge transport losses due to anode PTL and overviews relevant characterization techniques to monitor and mitigate the efficiency losses for improved electrolyzer performance. • Investigate the role of PTL structure on water management inside the stack. • Analysis the role of bubble generation and elimination for efficient mass transport. • Elucidate the impact of ICR between the PTL and catalyst layers on cell performances. • Summarize in-situ and ex-situ characterization techniques for PTL transport study.