Fig. 4: Simulation and experimental results of PEM performance.

a MSD vs time curve of H3O+ in Nafion under different λ. 2D number-density maps of H2O and H3O+ in the X-Y plane (0.2 nm thickness) at different λ: b 4, c 8, d 16, and e 22. f Experimentally determined PEM’s σ under different temperatures and RH. g I–V curves comparing experimental data with simulated results using σ under normal λ and water starved (λ = 2) conditions. The inset shows an enlarged view of the data for λ = 2. h Temperature distribution contours along the X-Y coordinate plane under different operating conditions, with water flow direction indicated by the blue arrow. The upper panel shows normal operating conditions at 100 A, while the lower panel shows water starvation conditions (λ = 2) at 10 V, 23 A. Prefix letter: A-anode, C-cathode; CH channel; PTL porous transport layer; CL catalytic layers.