Complex mechanisms of PEMFC performance variations influenced by both structural deformation and contact resistance under the clamping force.

The performance of proton exchange membrane fuel cells (PEMFCs) is influenced by the clamping force applied during assembly. However, the mechanisms are complex and many remain unveiled. This study addresses the effects of structural deformation and electrical contact resistance (ECR) caused by clamping force on the PEMFC performance. The individual and coupled effects of the structural deformation of the gas diffusion layer (GDL) and the ECR between the GDL and bipolar plate (BP) are discussed in detail, and positive and negative factors influencing the PEMFC performance and their competition relations are revealed. The optimal clamping force is determined by both the structural deformation and ECR. The optimal clamping force for PEMFC varies across different operating voltage ranges. The optimal clamping force is between 0.5 MPa and 1 MPa for low voltage range, and it is 2 MPa for medium voltage range, and the clamping force has minimal impact on PEMFC performance for high voltage range. The influence of clamping force remains consistent across various PEMFC operating temperatures and relative humidity levels. [Display omitted] • A fuel cell performance model under clamping force is developed. • Effects of structural deformation and contact resistance are investigated. • Mechanisms of fuel cell performance variations under the clamping force are revealed. • Optimal clamping forces for different fuel cell voltage ranges are determined. • The results can guide the design and assembly process of fuel cell. [ABSTRACT FROM AUTHOR]