Electrocatalyst for solid polymer fuel cell

Patent metadata

Field	Value
Publication number	US-9799903-B2
Application number	US-201113880393-A
Country	US
Kind code	B2
Filing date	Oct 21, 2011
Priority date	Oct 22, 2010
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

Provided is an electrocatalyst for solid polymer fuel cells capable of increasing the active surface area for reactions in a catalyst component, increasing the utilization efficiency of the catalyst, and reducing the amount of expensive precious metal catalyst used. Also provided are a membrane electrode assembly that uses this electrocatalyst and a solid polymer fuel cell. An electrocatalyst for a solid polymer fuel cell is provided with a catalyst and solid proton conducting material. A liquid conductive material retention part that retains a liquid proton conducting material that connects the catalyst and solid proton conducting material is provided between the same. The surface area of the catalyst exposed within the liquid conductive material retention part is larger than the surface area of the catalyst in contact with the solid proton conducting material.

First claim

The invention claimed is:

1. A polymer electrolyte fuel cell comprising an electrolyte membrane between an anode and a cathode, each comprising electrocatalyst,
a pair of gas diffusion layers; and
separators each having gas channels in a surface that faces a respective gas diffusion layer, the electrocatalyst comprising particles, each particle comprising:
a conductive catalyst support particle comprising:
liquid conductive material retaining parts formed of pores having a surface pore opening through an exterior surface of the conductive catalyst support particle and having a depth within the catalyst support particle;
a liquid proton-conductive material held within the liquid conductive material retaining parts; and
solid proton-conductive material coating a majority of an exterior of the conductive support particle along with the surface pore openings of the liquid conductive material retaining parts; and

active catalyst particles supported entirely within the liquid conductive material retaining parts of each conductive catalyst support particle, the active catalyst particles being a metal that is directly supported by the conductive catalyst support particle;
wherein the liquid proton-conductive material conductively connects the active catalyst particles to the solid proton-conductive material in a proton-conductive manner and is disposed between the active catalyst particles in the liquid conductive material retaining parts and the solid proton-conductive material,
a physical contact area between the active catalyst particles and the solid proton-conductive material is smaller than an area of the active catalyst particles exposed in the liquid conductive material retaining part, and
wherein the electrocatalyst comprises particles with a first type of solid proton-conductive material and particles with a second type of solid proton-conductive material, the first type of solid proton-conductive material having a lower equivalent weight than that of the second solid proton-conductive material, and the only particles of the electrocatalyst used in a region of the anode or the cathode where a relative humidity of gas in the gas channels is 90% or less are particles with the first type of solid proton-conductive material.

2. The polymer electrolyte fuel cell according to claim 1 , wherein the liquid conductive material retaining part is filled with the liquid proton-conductive material, and an electrical double layer capacitance formed at a catalyst/solid proton-conductive material interface is smaller than an electrical double layer capacitance formed at a catalyst/liquid proton-conductive material interface.

3. The polymer electrolyte fuel cell according to claim 1 , wherein the active catalyst particles in the liquid conductive material retaining parts is not in physical contact with the solid proton-conductive material.

4. The polymer electrolyte fuel cell according to claim 1 , wherein the conductive support particle is carbon black.

5. The polymer electrolyte fuel cell according to claim 1 , wherein an equivalent weight of the solid proton-conductive material is 1200 g/eq. or less.

6. The polymer electrolyte fuel cell according to claim 1 , wherein the metal of the active catalyst particles is at least one metal selected from the group consisting of Pt, Ir, Co, Ni, Fe, Cu, Ru, Ag, and Pd.

7. The polymer electrolyte fuel cell according to claim 1 , wherein the solid proton-conductive material having the lowest equivalent weight has an equivalent weight of 900 g/eq. or less.

8. The polymer electrolyte fuel cell according to claim 1 , wherein the solid proton-conductive material having the lowest equivalent weight is used in a region of the anode or the cathode where a temperature is higher than an average temperature at an inlet and an outlet of cooling water.

9. The polymer electrolyte fuel cell according to claim 1 , wherein the solid proton-conductive material having the lowest equivalent weight is used in a region of the cathode or anode that extends from at least one of a fuel gas supply port and an oxidant gas supplying port to a point within ⅗ of a channel length from a respective port.

Assignees

• Iden Hiroshi
• Ohma Atsushi
• Sakai Kei
• Satou Kazuyuki
• Ono Yoshitaka
• Tanaka Hiroyuki
• Akizuki Ken
• Nissan Motor

Inventors

• Iden Hiroshi
• Ohma Atsushi
• Sakai Kei
• Satou Kazuyuki
• Ono Yoshitaka
• Tanaka Hiroyuki
• Akizuki Ken

Classifications

• H01M4/9083

  on carbon or graphite · CPC title

• H01M4/926

  on carbon or graphite · CPC title

• H01M4/9058

  of noble metals or noble-metal based alloys · CPC title

• H01M4/92

  Metals of platinum group (H01M4/94 {, H01M4/9058} take precedence) · CPC title

• H01M8/1007

  with both reactants being gaseous or vaporised (H01M8/12 takes precedence) · CPC title