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A gradient pore size structure gas diffusion layer (GDL) was prepared using a pore-making agent, resulting in improved performance of proton exchange membrane fuel cells (PEMFC). The introduction of the pore-making agent altered the pore size distribution, increasing capillary pressure difference and improving water and gas transmission. The maximum power density of the GDL was increased by 37.1-40.3% compared to a commercial GDL.

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What they did

System
MFC

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Abstract

Abstract In this paper, a gradient pore size structure gas diffusion layer (GDL) was prepared. The pore structure of microporous layers (MPL) were controlled by pore-making agent ammonium bicarbonate (NH 4 HCO 3 ). The effects of the two-stage MPL and the different pore size structures in the two-stage MPL on the performance of proton exchange membrane fuel cells (PEMFC) were investigated. The results of the conductivity and water contact angle tests showed that the GDL had outstanding conductivity and good hydrophobicity. The results of the pore size distribution test indicated that the introduction of a pore-making agent altered the pore size distribution of the GDL as well as increased the capillary pressure difference within the GDL. Specifically, there was an increase in pore size within the 7-20 μm and 20-50 μm ranges, which improved the stability of water and gas transmission within the fuel cell. The maximum power density of the GDL03 was increased by 37.1% at 40% humidity, 38.9% at 60% humidity, and 40.3% at 100% humidity when compared to the commercial GDL29BC in a hydrogen-air environment. The design of gradient MPL ensured that pore size between carbon paper and MPL changed from an initially abrupt state to a smooth transition state, which greatly improved water and gas management capabilities of proton exchange membrane fuel cell.

Key findings

  • The GDL had outstanding conductivity and good hydrophobicity.
  • The pore size distribution of the GDL was altered, with an increase in pore size within the 7-20 μm and 20-50 μm ranges.
  • The maximum power density of the GDL was increased by 37.1-40.3% compared to a commercial GDL.

Keywords

Microporous materialProton exchange membrane fuel cellChemical engineeringAmmonium bicarbonateWater vaporHumidity

Identifiers

DOI
10.21203/rs.3.rs-2834709/v1
Journal
Research Square
Year
2023