Abstract
At high current densities, oxygen bubble formation limits the performance of polymer electrolyte membrane (PEM) water electrolyzers, particularly due to bubble accumulation at the porous transport layer (PTL)/catalyst layer (CL) interface. Efficient bubble removal from the PTL/CL interface is therefore crucial for PEM water electrolyzers1,2. Bubble transport at the PTL/CL interface is dominated by mechanical compression 3,4. However, it is still unclear how mechanical compression impacts bubble transport at the PTL/CL interface, due to difficulties in capturing the multiphase flow and differentiating liquid/gas in the pores of the titanium PTL. Thanks to its spatial resolution and high transmissivity for titanium, neutron imaging enables visualization of the bubble distribution in the PTL hence allowing for the identification of the role of compression in the bubble transport.We conducted operando neutron imaging for PEM water electrolyzers and examined the relationship between compression ratio and electrochemical performance. Neutron imaging results showed that the through-plane bubble distributions became more homogeneous as compression increased. Additionally, pore network modelling simulations indicated that compression-induced catalyst coated membrane intrusion homogenized the bubble distribution in the PTL. We identified an optimal compression condition for enhanced interfacial bubble transport that can contribute to the next-generation material development to improve the efficiency of PEM water electrolyzers at high current densities with low mass transport losses. References J. K. Lee and A. Bazylak, Joule, 5, 19–21 (2021).S. Yuan et al., Prog. Energy Combust. Sci., 96, 101075 (2023).T. Schuler, T. J. Schmidt, and F. N. Büchi, J. Electrochem. Soc., 166, F555–F565 (2019).A. Martin et al., J. Electrochem. Soc., 169, 014502 (2022).
Published Version
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