Performance Modeling and Current Mapping of Proton Exchange Membrane Electrolyzer Cells with Novel Thin/Tunable Liquid/Gas Diffusion Layers

Highlights: •A new LGDL sub-model for the interfacial contact resistance was established. •The effects of the TT-LGDL pore morphologies on roughness factor in the Butler-Volmer equations were established and validated. •The CL resistances were divided into in-plane electron and through-plane proton resistances based on TT-LGDL/CL structures. •Catalyst utilization and electrochemical reaction are highly controlled by CL in-plane electron conductivities. -- Abstract: The novel titanium thin/tunable liquid/gas diffusion layers (TT-LGDLs) with precisely controllable pore morphologies have achieved superior multifunctional performance in proton exchange membrane electrolyzer cells (PEMECs) with its advantages of ultra-thin thickness (25 μm), planar surface, and straight-through pores. By taking advantage of the precise pore morphology of TT-LGDLs, a comprehensive computational model is developed in MATLAB/Simulink platform to simulate the CL current distribution, and PEMEC electrochemical performance. The interfacial contact resistances between the TT-LGDLs and catalyst layers (CLs), and PEMEC overpotentials are closely correlated to the TT-LGDL pore diameter and porosity. In addition, the roughness factor, which is a critical coefficient in simulating the activation overpotential in Butler-Volmer equation, is also modeled as a function of TT-LGDL morphologies. More importantly, a novel two-dimensional (2D) CL resistance model that consists of both in-plane and through-plane resistances is also developed to predict the current distribution on the CLs. The present model can precisely match the experimental results and effectively calculate the PEMEC performance with different TT-LGDL morphologies and operating temperatures. Results obtained from the present model will provide a deep understanding of the functions of TT-LGDL morphology, and also help to optimize the design and fabrication of both the TT-LGDLs and CLs.