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Diffusion media with vapor deposited fluorocarbon polymer

A technology of fluorocarbon polymers and diffusion media, which is applied in the direction of electrolyte treatment of solid electrolyte batteries, electrical components, fuel cell components, etc., and can solve the problems of reduced hydrophobicity of media

Inactive Publication Date: 2007-10-24
GM GLOBAL TECH OPERATIONS LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] PTFE-coated diffusion media have exhibited defects, as demonstrated for example by measuring the dynamic contact angle in the standardized Wilhelmy test, in some cases the hydrophobicity of the coated media decreases over time

Method used

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  • Diffusion media with vapor deposited fluorocarbon polymer
  • Diffusion media with vapor deposited fluorocarbon polymer
  • Diffusion media with vapor deposited fluorocarbon polymer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0078] Toray 060 carbon fiber paper (product of Toray Industries, USA) was coated with fluorocarbon polymer by hot wire vapor deposition. The total incorporation of PTFE on the substrate paper was about 7% based on the total weight of substrate and coating.

[0079] The fluorine distribution map drawn by energy dispersive spectroscopy shows the uniform distribution of fluorine on the surface. The fluorine (F) profile measured through the thickness of the paper by electron probe microanalysis (EPMA) clearly shows the penetration of fluorine into the carbon fiber paper substrate, although the concentration in the center of the substrate is substantially less than that at the surface . When the vapor-deposited coating is applied from both sides of the substrate, a bimodal F distribution can be observed, similar to that observed from conventional dip-dried samples.

Embodiment 2

[0081] External aging tests were carried out by immersing the coated paper of Example 1 in 15% hydrogen peroxide at 65°C for 7 days. In the Wilhelmy test, the coated side showed no decrease in receding contact angle from 140, showing no loss of hydrophobicity with aging, while the uncoated side showed a receding contact angle of 20 degrees, showing loss of hydrophobicity with aging. Comparative samples prepared from dip-dried and sintered PTFE coatings also showed a decrease in receding contact angle to 10-20 degrees with aging.

Embodiment 3

[0083] Flat Toray 060 substrates were first coated with a microporous layer (MPL) on the substrate side. The MPL paste composition contained 2.4 grams of acetylene black, 31.5 mL of isopropanol, 37 mL of deionized water, and 1.33 grams of a 60% by weight dispersion of PTFE in water. The microporous layer had a final solids loading of 1.15 mg / cm 2 .

[0084] PTFE is then vapor deposited, with the MPL side facing the substrate carrier, and the opposite side of the MPL facing the gas injection port. The PTFE loading by vapor deposition was about 7 wt% relative to the Toray 060 substrate. This is the first sample.

[0085] A second sample was prepared in a similar manner, but PTFE deposition was carried out by immersing the substrate in a 3% PTFE solution (diluted from Dupont T-30) for 4 minutes, followed by IR at 64°C from the side immersed in the substrate. After drying for 10 minutes, the MPL was applied to the opposite side of the substrate, and the MPL and dip-dried PTFE co...

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Abstract

Fuel cells contain diffusion media having vapor-deposited fluorocarbon polymers on a conductive substrate. A diffusion medium for use in a PEM fuel cell contains hydrophobic and hydrophilic areas for improved water management. A hydrophobic polymer such as a fluororesin is vapor deposited on the paper to define the hydrophobic areas; hydrophilic areas are those areas uncovered by hydrophobic polymer, or covered by an additionally deposited hydrophilic polymer.

Description

technical field [0001] The present invention relates to fuel cells and methods for improving water management during fuel cell operation. The invention also relates to methods of preparing diffusion media for fuel cells. Background technique [0002] Fuel cells are increasingly being used as power sources for electric vehicles and other applications. A typical fuel cell has a membrane electrode assembly (MEA) with a catalytic electrode and a proton exchange membrane (PEM) formed between the electrodes. During operation of the fuel cell, water is produced at the cathode based on the electrode chemical reaction between hydrogen and oxygen that occurs in the MEA. Efficient operation of a fuel cell depends on the ability to provide effective water management in the system. [0003] Gas diffusion media play an important role in PEM fuel cells. In general, the diffusion media need to facilitate the removal of product water from the cathode catalyst laye...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M8/24H01M8/10H01M8/02H01M4/86H01M4/88
CPCH01M8/0245Y02E60/521H01M8/04291H01M8/1002H01M8/1007Y02E60/50
Inventor 纪纯新M·马蒂亚斯
Owner GM GLOBAL TECH OPERATIONS LLC