Maximum tolerable temperature difference in anion exchange membrane fuel cells for high-performance operation

The temperature distribution in anion exchange membrane fuel cells (AEMFCs) is critical to cell performance because temperature is closely related to the cell's thermal and water management. In this work, a 3D multi-physics model is developed to investigate the temperature distribution, water management, and electrochemical performance of AEMFCs employing gas diffusion layers (GDLs) with diverse heat transfer characteristics. The results show that localized high temperatures within the cell lead to membrane dehydration, resulting in elevated ohmic impedance and degraded cell performance. However, increasing GDL's thermal conductivity helps to diminish the temperature gradient within the cell and ensures that the membrane is sufficiently hydrated to lower the ionic impedance, consequently improving cell performance. In isotropic GDLs, excellent performance is achieved when the thermal conductivity exceeds 3 W/(m⋅K). For anisotropic GDLs, elevating the through-plane thermal conductivity facilitates heat dissipation under the rib and channel, whereas in-plane conductivity modifications primarily influence regions under the channel. Moreover, temperature differences below 5 °C are acceptable in the AEMFC, but above this threshold, improved heat dissipation is necessary.