Preparation of graded microporous layers for enhanced water management in fuel cells

Abstract

The newly prepared gas diffusion layer (GDL) was studied in this article. The new GDL mainly includes a carbon paper layer and two microporous layers (MPLs) on the same side of carbon paper. The two MPLs were fabricated by using conductive carbon blacks of two different carbon morphology, Vulcan XC‐72, and acetylene black carbon, respectively. From the results of the water contact angle and conductivity, it was found that the GDL prepared by spraying has not only good hydrophobicity but also low resistivity. Polarization curve and electrochemical impedance spectroscopy indicated that the spraying sequence of two different carbon black pastes seriously affects the fuel cell performance, and the mercury intrusion test proved that the change in the fuel cell performance is due to the change in the pore‐size distribution of the newly prepared GDL. By comparing with commercial GDL29BC, the GDL first sprayed with a layer of acetylene black carbon and then a layer of Vulcan XC‐72 has more pore size of 7–20 μm and 20–100 μm to improve the water and gas management capability of proton exchange membrane fuel cells. When the humidity is 60%, the maximum power density is increased by 25%, and when the humidity is 100%, it is increased by 12%.

Gas Diffusion Layer for Proton Exchange Membrane Fuel Cells: A Review

“…Lin et al [94] prepared a gradient double-layer MPL structures by using conductive carbon black with different particle size, so as to achieve gradual change of pore size from GDL to CL, with the aim to improve the water management ability. They therefore designed a GDL with an MPL containing two layers that were different in pore size (as shown in Figure 9a) by using two types of conductive carbon blacks-one is acetylene carbon black (7-20 µm), the other is Vulcan XC-72 (20-100 µm).…”

Managing the Pore Morphologies of Microporous Layers for Polymer Electrolyte Fuel Cells with a Solvent-Free Coating Technique

“…In addition, MPLs with a porosity gradient experience internal capillary pressure. Similarly, other researchers have shown that MPLs with a porosity gradient introduced using ammonium chloride exhibit electrochemical performance superior to that of MPLs with a uniform pore-size distribution. − The addition of thermally expandable GPs has been reported as another approach for the fabrication of MPLs with a porosity gradient . MPLs with gradient hydrophobicity have also been effective for draining water accumulated in GDLs .…”

“…MPLs with gradient hydrophobicity have also been effective for draining water accumulated in GDLs . To fabricate MPLs with gradient features requires at least one step of the wet-coating process to be repeated. ,,− However, repeated drying and annealing processes for the fabrication of multilayers significantly increase the product cost and the environmental impact.…”

Chemically Engineered Microporous Layer with Superhydrophobicity for High-Performance Proton Exchange Membrane Fuel Cells

“…11,16 The introduction of polymer hydrophobic agents into the MPL is beneficial for the water drainage. 17 However, this physical mixing method is deficient on several levels. First, due to the difference in surface physical properties and solubility in solvents between the carbon matrix elements and the hydrophobic agents, they tend to agglomerate individually and undergo phase separation, resulting in an inhomogeneous distribution of hydrophobic agents in the mixture and cannot avoid water flooding of the electrode efficiently.…”