Effects of mechanical compression on the performance of polymer electrolyte fuel cells and analysis through in-situ characterisation techniques - A review

Abstract

One of the factors that affect the polymer electrolyte fuel cell (PEFC) performance is the mechanical compression inside the stack. Although this compression plays an important role to ensure efficient gas sealing along with optimised electrical and thermal conductivities during PEFCs operation, excessive mechanical pressure may worsen the fuel cell performance through reducing the porosity and transport ability of PEFC components. In the last few years, intensive research studies have focused on the gas diffusion layers (GDLs) due to the strong relation of their compressibility with the performance of the PEFCs. A few review papers investigating the compression effect on individual fuel cell components have already been published. However, the evaluation of this effect on an operating PEFC has rarely been reviewed. This paper covers a comprehensive overview of the studies that have focused on the relationship between mechanical compression and the observed performance of a PEFC operating in real life conditions (in-situ). In this study, the effects of GDL properties with respect to the applied mechanical compression and the operating conditions are investigated. Much more work in literature has focused on GDL properties. Thus, an extended discussion is dedicated to this cell element in this paper.

Engineering Catalyst Layers for Next‐Generation Polymer Electrolyte Fuel Cells: A Review of Design, Materials, and Methods

“…In situ diagnostic techniques have also been utilized to study the effects of compression, predominantly through polarization curves ( Figure 55 a). [ 529 ] Compression has little impact on performance at low current densities. As higher current densities are reached and more water is produced, water management complications arise, with earlier onsets of flooding for increasing GDL compression.…”

Design of experiments on the effects of linear and hyperelastic constitutive models and geometric parameters on polymer electrolyte fuel cell mechanical and electrical behaviour

“…Experimentally, there are two major in-situ techniques used to measure contact pressure distributions [8]. The first technique uses pressure sensitive films composed of two polyester based sheets which one of them is coated with a layer of micro-encapsulated colour forming material and the other one is coated with a layer of colour developing material [35].…”

“…Great efforts have been done toward the commercialization of PEMFC in energy market but a larger deployment involves enhancing their efficiency, lifetime [4,5,6], reducing their costs and improving electrical power production. The link between the energetic performance of a PEMFC and external-internal mechanical excitations [7] ,as well as environmental conditions is one of the significant factors influencing its industrialization [8].…”

“…However, to the knowledge of the authors, the comparison between these linear and hyperelastic behaviours is little explored. The experimental study described in [8] point out that "contact resistance was found to decrease non-linearly with compression: more than 75% of reduction was attained at 2.5 MPa". The representativeness of the preliminary models involves the study of nonlinearities, in particular for GDL [16].…”

Effect of cell compression on the performance of a non–hot‐pressed MEA for PEMFC

“…The gasket material also plays an important role in controlling the GDL compression, because depending upon the material properties different deformation will be obtained [6]. Cell assembly compression affects the cell performance [7]. A high cell assembly compression provides a better electrical contact between the cell components and reduces the ohmic loss.…”