Gas diffusion substrate

Patent metadata

Field	Value
Publication number	US-2017062836-A1
Application number	US-201615350345-A
Country	US
Kind code	A1
Filing date	Nov 14, 2016
Priority date	Feb 12, 2009
Publication date	Mar 2, 2017
Grant date	—

Abstract

A process for preparing gas diffusion substrate including a non-woven fibre web, thermally conductive materials and a carbonaceous residue, wherein the thermally conductive materials and carbonaceous residue are embedded within the non-woven fibre web and wherein the thermally conductive materials have a maximum dimension of between 1 and 100 μm and the gas diffusion substrate has a porosity of less than 80% is disclosed. The substrate has particular use in phosphoric acid fuel cells.

First claim

1 . A process for preparing a gas diffusion substrate, said process comprising the steps of:
(i) impregnating a non-woven fibre web with a mixture of a phenolic resin binder and thermally conductive materials selected from the group consisting of nanofibers, nanotubes and nanographene platelets, to give an impregnated web; (ii) curing the phenolic resin binder within the non-woven fibre web at a temperature of 100-250° C.; (iii) a first heat-treatment step of the impregnated web at 600-1000° C. to carbonize the phenolic resin binder to leave a carbonaceous residue; and (iv) a second heat-treatment step at 1800-3000° C. to provide the gas diffusion substrate.

2 . The process according to claim 1 , wherein the second heat-treatment step is at 2000-2300° C.

3 . The process according to claim 1 , wherein the first heat-treatment step is carried out in a non-oxidising gas atmosphere.

4 . The process according to claim 3 , wherein the non-oxidising gas atmosphere comprises nitrogen or carbon dioxide.

5 . The process according to claim 1 , wherein the gas diffusion substrate prepared by said process has a through-plane thermal conductivity of at least 3 W/m.K at a pressure of 1000 kPa.

6 . The process according to claim 1 , wherein before step (iii), two or more impregnated non-woven fiber webs are laminated.

7 . The process according to claim 6 , wherein the two or more impregnated non-woven fiber webs are laminated cross-plied.

8 . The process according to claim 6 , wherein the two or more impregnated non-woven fiber webs are laminated non-cross-plied.

9 . The process according to claim 6 , wherein the lamination is carried out at a temperature of between 150° C. and 160° C.

10 . The process according to claim 6 , wherein the laminated non-woven fiber webs have a thickness of 0.05 mm to 10 mm

Assignees

• Johnson Matthey Fuel Cells Ltd
• Technical Fibre Products Ltd

Inventors

• Jeschke Michael
• Sharman Jonathan Brereton

Classifications

• H01M4/8807 Primary

  Gas diffusion layers · CPC title

• H01M4/86

  Inert electrodes with catalytic activity, e.g. for fuel cells · CPC title

• H01M4/8605 Primary

  Porous electrodes · CPC title

• H01M8/086

  Phosphoric acid fuel cells [PAFC] · CPC title

• Y10T442/20

  Coated or impregnated woven, knit, or nonwoven fabric which is not [a] associated with another preformed layer or fiber layer or, [b] with respect to woven and knit, characterized, respectively, by a particular or differential weave or knit, wherein the coating or impregnation is neither a foamed material nor a free metal or alloy layer · CPC title