Gas Diffusion Layer with a Regular Hydrophilic Structure Boosts the Power Density of Proton Exchange Membrane Fuel Cells via the Construction of Water Highways

Abstract

The gas diffusion layer (GDL) is an essential carrier for the mass transmission of proton exchange membrane fuel cells (PEMFCs), which decides the peak power density of PEMFCs. Herein, a gas diffusion layer with a regularly arranged hydrophilic and hydrophobic pattern structure was prepared by a template method combined with the ultrasonic spray process. The peak power density was enhanced by 30% (from 520 to 678 mW/cm2) compared to an unpatterned structure, and the breakthrough pressure of the GDL was reduced from 13.61 to 2.96 kPa. In addition, the finite element analysis (FEA) results indicate that the polarization curve of calculation was highly consistent with the experimental results. Importantly, the capillary pressure of the hydrophilic area was about 0.3 kPa, much lower than that of the hydrophobic area (2 kPa), demonstrating that the hydrophilic and hydrophobic synergistic structure reduced the water transmission resistance in separating water and oxygen and builds a high-speed channel for water transmission.

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

“…15 In a conventional fabrication of MPL, polymer hydrophobic agents, such as polytetrafluoroethylene (PTFE) and polyvinylidene difluoride (PVDF), are usually physically mixed with carbon materials. 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.…”

“…The drainage capability of the GDL is critical in improving the performance of PEMFCs especially at high current densities. − It has been demonstrated that the construction of a microporous layer (MPL) on the surface of a carbon paper supporting layer (SL) can reduce the contact resistance of the membrane electrode while significantly enhancing its drainage capacity . In a conventional fabrication of MPL, polymer hydrophobic agents, such as polytetrafluoroethylene (PTFE) and polyvinylidene difluoride (PVDF), are usually physically mixed with carbon materials. , The introduction of polymer hydrophobic agents into the MPL is beneficial for the water drainage . However, this physical mixing method is deficient on several levels.…”

Control of Liquid Water Transport in Cathode of PEFC Using Wettability-Patterned Electrodes

“…In order to address this issue, it is necessary to design an electrode structure that can actively remove the liquid water that has accumulated in the PEFC cathode during operation. Several researchers have proposed electrode structures for water removal (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). Furthermore, several researchers have designed perforated electrode structures to improve the removal of water from the gas diffusion layer into the channel (1)(2)(3)(4)(5).…”

“…However, perforated structures restrict the transportation of electrons and reduce the reaction sites. Other structures include wettability patterned electrodes that improve drainage by providing hydrophilic and hydrophobic regions in the cathode GDL and introduce a drainage path for the water generated during cell operation (6)(7)(8)(9)(10)(11)(12)(13). Various methods have been proposed to fabricate wettability-patterned electrodes.…”

“…Various methods have been proposed to fabricate wettability-patterned electrodes. These methods include graft polymerization of hydrophilic monomers by irradiating the area to be given hydrophilicity with electron beams or radiation (6)(7)(8)(9)(10)(11), creating hydrophilic areas using ultrasonic spray (12), and coating fluorinated resins using an airbrush and masking templates (13). However, these methods require specialized equipment and involve complex procedures.…”