Effects of assembling method and force on the performance of proton‐exchange membrane fuel cells with metal foam flow field

Abstract

Recently, highly porous metal foams have been used to replace the traditional open-flow channels to improve gas transport and distribution in the cells. Deformation of flow plate, gas diffusion layer (GDL), and metal foam may occur during assembling. When the cell size is small, the deformation may not be significant. For large area cells, the deformation may become significant to affect the cell performance. In this study, an assembling device that is capable of applying uniform clamping force is built to facilitate fuel cell assembling and alleviate the deformation. A compressing plate that is the same size of the active area is used to apply uniform clamping force before surrounding bolts are fastened. Therefore, bending of the flow plate and deformation of GDL and metal foam can be minimized. Effects of the clamping force on the microstructures of GDL and metal foam, various resistances, pressure drops, and cell performance are investigated. Distribution of the contact pressure between metal foam and GDL is measured by using pressure sensitive films. Field-emission scanning electron microscope is used to observe the microstructures. Electrochemical impedance spectroscopy analysis is used measure resistances. The fuel cell performance is measured by using a fuel cell test system. For the cell design used in this study, the optimum clamping force is found to be 200 kgf. Using this optimum clamping force, the cell performance can be enhanced by 50%, as compared with that of the cell assembled without using clamping plates. With appropriate clamping force, the compression force distribution across the entire cell area can approach uniform. This enables uniform flow distribution and reduces mass transfer resistance. Good contact between GDL and metal foam also lowers the interface resistance. All these factors contribute to the enhanced cell performance.

A Study of Contact Pressure with Thermo-Mechanical Coupled Action for a Full-Dimensional PEMFC Stack

“…They also found that a higher contact pressure is beneficial to heat conduction, improving the uniformity of the temperature field and avoiding local hot spots. Weng et al [24] studied the contact pressure between the metal BPP and GDL under different clamping forces. A polarization curve test and electrochemical spectrum (EIS) experiment were carried out.…”

Parametric Finite Element Analysis of Belt Type Assembly of PEMFC

“…Proton exchange membrane fuel cell (PEMFC) has become one of the most studied and widely used fuel cells because of its small size, high power density and high energy conversion efficiency [1][2][3]. PEMFC is mainly composed of endplates, insulating plates, collector plates, bipolar plates and membrane electrodes assembly [4].…”

Cathode Design for Proton Exchange Membrane Fuel Cells in Automotive Applications

“…This thus reduces oxygen mass transport to reaction sites of the catalyst finally resulting in poor fuel cell power performance [13]. Accordingly, various technologies, including 3D mesh flow field plates [14,15], ordered structure electrodes [16] and hydrophobic GDLs [17], have been investigated to overcome the water management issues.…”