Multilayer structure incorporating a mat of carbon nanotubes as diffusion layer in a pemfc

Patent metadata

Field	Value
Publication number	US-2019123359-A1
Application number	US-201816165277-A
Country	US
Kind code	A1
Filing date	Oct 19, 2018
Priority date	Oct 20, 2017
Publication date	Apr 25, 2019
Grant date	—

Abstract

A multilayer structure, of use as composite diffusion layer in a proton-exchange membrane fuel cell, including at least one mat of carbon nanotubes having a unit diameter of less than or equal to 20 nm, defining at least one face of the structure, the mat of carbon nanotubes being superposed on a support based on carbon fibres. It also relates to a process for preparing such a multilayer structure and to the use thereof for an electrode of a PEMFC.

First claim

1 . A multilayer structure, of use as composite diffusion layer in a proton-exchange membrane fuel cell, comprising at least one mat of carbon nanotubes having a unit diameter of less than or equal to 20 nm, defining at least one face of said structure, said mat of carbon nanotubes being superposed on a support based on carbon fibres.

2 . The multilayer structure according to claim 1 , wherein the interface between the support based on carbon fibres and the mat of carbon nanotubes which is superposed thereon comprises a stack of thin layers comprising, in this order, from the support up to the mat of nanotubes:
a/ optionally a metal layer made of metal M or layer made of metal alloy based on the metal M or layer made of graphene; b/ a titanium layer; c/ an aluminium layer; d/ a layer of material(s) that catalyse(s) the growth of carbon nanotubes.

3 . The multilayer structure according to claim 1 , wherein the CNT mat has a density greater than or equal to 10 11 CNT per cm 2 , preferably between 10 11 and 10 13 CNT per cm 2 .

4 . The multilayer structure according to claim 1 , wherein the CNT mat has a density between 10 11 and 10 13 CNT per cm 2 .

5 . The multilayer structure according to claim 1 , wherein the CNT mat has a thickness between 1 and 200 μm.

6 . The multilayer structure according to claim 1 , wherein the CNT mat has a thickness between 5 and 100 μm.

7 . The multilayer structure according to claim 1 , wherein the CNT mat has a thickness between 5 and 50 μm.

8 . The multilayer structure according to claim 1 , wherein the support based on carbon fibres is impregnated over all or part of its volume by at least one hydrophobic agent, and/or whose face opposite the one supporting said CNT mat is hydrophobic or coated with a film incorporating at least one hydrophobic agent.

9 . The multilayer structure according to claim 8 , wherein the support based on carbon fibres is impregnated over all or part of its volume by at least one hydrophobic agent, and/or has, on its face opposite the one supporting said CNT mat, a film incorporating at least one hydrophobic agent.

10 . The multilayer structure according to claim 8 , wherein said hydrophobic agent is selected from fluoropolymers and perfluoropolymers.

11 . The multilayer structure according to claim 8 , wherein said hydrophobic agent is selected from poly(vinylidene fluoride), polytetrafluoroethylene, fluorinated ethylene propylene, poly(vinylidene fluoride-co-hexafluoropropylene), poly(ethylene-co-tetrafluoroethylene) and perfluoroalkoxy.

12 . The multilayer structure according to claim 1 , comprising two CNT mats defining two opposite faces of said structure.

13 . The multilayer structure according to claim 1 , wherein the support based on carbon fibres comprises:
a substrate based on carbon fibres; and a layer based on carbon fibres borne by at least one of the faces of said substrate, comprising less than 30% by weight of hydrophobic agent; said layer having, on at least its face opposite said substrate, said mat of carbon nanotubes.

14 . The multilayer structure according to claim 13 , wherein the substrate based on carbon fibres is hydrophobic.

15 . The multilayer structure according to claim 13 , wherein the substrate based on carbon fibres is impregnated by at least one hydrophobic agent.

16 . The multilayer structure according to claim 13 , wherein said substrate has between 2% and 40% by weight of hydrophobic agent(s), relative to its total weight.

17 . The multilayer structure according to claim 13 , wherein the layer based on carbon fibres comprises less than 10% by weight of hydrophobic agent.

18 . The multilayer structure according to claim 8 , wherein the substrate is intercalated between two layers based on carbon fibres, comprising less than 30% by weight of hydrophobic agent, preferably being free of hydrophobic agent, each of the layers having, on its face opposite said substrate, a CNT mat.

19 . The multilayer structure according to claim 8 , further comprising a mat of carbon nanotubes intercalated between at least one layer based on carbon fibres and said substrate.

20 . The multilayer structure according to claim 1 , wherein the support based on carbon fibres is formed of a solid substrate based on carbon fibres, said substrate having, on one of its faces, said mat of carbon nanotubes.

21 . The multilayer structure according to claim 20 , having on each of the two opposite faces of said substrate, a mat of carbon nanotubes.

22 . The multilayer structure according to claim 20 , wherein said substrate is impregnated, on its face opposite the one supporting the CNT mat, by at least one hydrophobic agent, and/or whose face opposite the CNT mat is hydrophobic or coated with a film comprising at least one hydrophobic agent.

23 . The multilayer structure according to claim 22 , wherein said substrate is impregnated, on its face opposite the one supporting the CNT mat, by at least one hydrophobic agent, and/or has, on its face opposite the one supporting the CNT mat a film comprising at least one hydrophobic agent

24 . The multilayer structure according to claim 22 , wherein the substrate is impregnated over a thickness, e, extending from its face opposite the one supporting the CNT mat, that is strictly less than the total thickness of the substrate.

25 . The multilayer structure according to claim 22 , wherein the substrate is impregnated over a thickness e representing less than 95% of the total thickness of the substrate.

26 . The multilayer structure according to claim 22 , wherein the substrate is impregnated over a thickness e representing less than 80% of the total thickness of the substrate.

27 . The multilayer structure according to claim 13 , wherein the layer based on carbon fibres borne by at least one of the faces of said substrate, comprises less than 10% by weight of hydrophobic agent.

28 . The multilayer structure according to claim 13 , wherein the layer based on carbon fibres borne by at least one of the faces of said substrate is free of hydrophobic agent.

29 . A process for preparing a multilayer structure, of use as composite diffusion layer in a proton-exchange membrane fuel cell, comprising at least the following steps:
(i) producing, on at least one of the faces of a support based on carbon fibres, comprising less than 30% by weight of hydrophobic agent, a catalytic stack of thin layers, comprising in this order: a/ optionally a metal layer made of metal M or layer made of metal alloy based on the metal M or layer made of graphene; b/ a titanium layer; c/ an aluminium layer; d/ a layer of material(s) that catalyse(s) the growth of carbon nanotubes; and (ii) growing a mat of carbon nanotubes on the stack according to a chemical vapour deposition technique, which is optionally plasma enhanced, and optionally hot-filament activated.

30 . The process according to claim 29 , wherein said support based on carbon fibres is submitted, prior to its use in step (i), to a heat treatment at a temperature of between 500° C. and 700° C., under an atmosphere of inert gas(es), air, hydrogen, oxygen, or a mixture of these gases.

31 . The process according to claim 29 , comprising at least the following steps:
(a1) producing, according to steps (i) and (ii), a

Assignees

• Commissariat Energie Atomique

Inventors

• Morin Arnaud
• Dijon Jean
• Ramos Raphael

Classifications

• H01M4/8807

  Gas diffusion layers · CPC title

• H01M8/0247

  characterised by the form (characterised by a channel configuration H01M8/0258) · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• H01M4/8626

  characterised by the form · CPC title