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To study the influence of anisotropic transport properties of porous layers (PLs) on the dynamic performance (DP) of fuel cells (FC), a numerical model was developed. The model uses self-compiled codes to couple the actual structure of PLs with its transport capability, while introducing a non-homogeneous model that reflects the effect of the actual agglomerate structure of the catalyst layer on the electrochemical reaction, based on the consideration of the internal heat transport and external heat exchange of FC, the three-phase transformation of water, the change of momentum, energy, species, and water transport with time, and finally realizes the transient changes of complete transport and reaction process inside the FC. Using the current density as the input load, the law of the anisotropic transport properties of PLs on the FC's DP was explored. The results show that among all properties, the proton conductivity has the most significant influence on DP indexes such as steady-state transition time, over/undershoot amplitude, the electrical conductivity and diffusivity have similar and significant effects, the thermal conductivity and permeability have minor and most negligible effects, respectively. When designing the material, structure and composition of the PLs, the focus should be on protons, electron conductivity and diffusivity. • The effect of porous layers anisotropy on the transient behavior of FC was analyzed. • Coupled structural parameters and transport properties of the porous layers. • The effect of the CL's actual agglomerate structure on FC performance is considered. • Pointed out the porous layers transport capability that should be enhanced in focus. [ABSTRACT FROM AUTHOR]

• A semicircular baffle flow field with helical structure is proposed. • Considering the anisotropic mass and heat transfer properties of the porous layers. • Considering the actual agglomerate structure of the cathode catalyst layer. • The optimized flow field increases the fuel cell's net power density by 11.42 %. To effectively improve the fuel cell (FC) mass transport capacity, a new flow field (FF) design with helical baffle at the cathode is proposed, which facilitates gas flow and mass transfer in both through- and in-plane directions. To fully understand the influence of various design parameters on the FC performance, a series of studies were carried out with a semicircular baffle as an example. The effect of the baffle structure on the complex heat and mass transport process is studied in detail to obtain the optimal baffle structure parameters. To simulate the complete transport process, a three-dimensional, multiphase, non-isothermal steady-state model was developed, embedding the anisotropic transport properties caused by the porous layer structures and the heterogeneous model of the actual agglomerate structure of the catalyst layer in the model. The results show that the helical baffles induce cross flow under the ribs while inducing forced convection, enhancing the oxygen supply in both directions. The FF structure with baffle height and pitch of 0.4 mm and 1.0 mm respectively has the maximum net power density. Taking the relative humidity = 50 % and 100 % as an example, the net power density is increased by 11.42 % and 5.72 % respectively compared with the original FF. [ABSTRACT FROM AUTHOR]

This review concentrated on proton exchange membrane fuel cell (PEMFC) water management, which introduces the latest research contents and progresses on membrane electrode assembly (MEA) components, and summarizes the influencing factors about the properties of them. The PEMFC's core component is MEA which consists of proton exchange membrane, catalyst layer, microporous layer and carbon fiber paper. The properties of each component have significant impacts on the fuel cell (FC) performance, and there will be strong interactions between some properties. Therefore, the FC performance is determined by the properties of each component and their interactions. It is the basis for the design of the high-performance FCs to clarify the influence mechanism of various properties and their interactions on the FC performance, but there is currently no summary on this aspect. Therefore, the conclusions about the same component or property drawn from all literatures are sorted and combined, so that we can intuitively know which literatures have studied and reached the conclusions, and comprehensively realize the influence mechanism of a certain property. Based on the development and achievement of each component in some aspects, this article makes some predictions and discussions on the future research direction and development prospects of each component. • The influence relationships between the properties of MEA components are discussed. • The influences of MEA components' properties on fuel cell performance are analyzed. • Pointed out the ambiguity in some conclusions and explained the possible reasons. • The joint effect of MEA components on the water management capability are presented. [ABSTRACT FROM AUTHOR]

In order to realize the fuel cell (FC) operation with higher power density, researchers have made various attempts to it. The innovative design of bipolar plate (BPP) can contribute about 20% to the volumetric power density increase. Mass transfer and drainage capacity are two keys of plate design. In order to improve its mass transfer capacity, many improvements have been made, such as baffle flow field (FF) and biomimetic FF. These FFs have their own advantages and disadvantages. For facilitate comparison, this article summarizes the influence of various FF designs, structures, flow patterns and other parameters on FC performance, and gives the BPP's development direction in the future. The effects of different FF structures, geometric parameters and arrangement forms on the uniformity of i distribution are summarized. The effects of contact area, channel design parameters such as channel width/rib ratio, fillet radius and channel size on the BPP's interfacial contact resistance are reviewed. Guidance is provided for designing FFs that can achieve more uniform i distribution and smaller contact resistance. The main manufacturing processes of BPPs are reviewed, and then the difficulties that need to be overcome in order to manufacture higher performance BPPs are pointed out. • The influences of various BPP flow field designs on FC performance are summarized. • The effects of BPP on current distribution and contact resistance are summarized. • The fabrication process of BPPs and existing difficulties are summarized. • The development directions of BPP fabrication and flow field design are predicted. [ABSTRACT FROM AUTHOR]