EP-4738480-A1 - CARBON MATERIAL FOR CATALYST CARRIER OF SOLID POLYMER FUEL CELL, CATALYST LAYER FOR SOLID POLYMER FUEL CELL, AND FUEL CELL

Abstract

A carbon material for a catalyst carrier of a solid polymer fuel cell, the carbon material including porous activated carbon black satisfying the following requirements (A) and (B). (A) A BET specific surface area S BET determined by BET analysis of a nitrogen gas adsorption isotherm is from 400 to 1200 m 2 /g. (B) A ratio ΔV fin /ΔV ini is from 0.75 to 0.95 in a case in which a difference between an amount (mL/g) of mercury absorption at a mercury intrusion pressure of 10 MPa and an amount (mL/g) of mercury absorption at a mercury intrusion pressure of 100 MPa after pressurization of the porous activated carbon black at a pressure of 100 MPa with a mold in a mercury porosimetry method and such a difference before pressurization of the porous activated carbon black at a pressure of 100 MPa with the mold are respectively defined as ΔV fin and ΔV ini .

Inventors

• IIJIMA, TAKASHI
• NEGI, NORIYUKI
• SHIMIZU, TAKAYUKI
• TADOKORO, KENICHIRO
• MASAKI, KAZUYOSHI

Assignees

• NIPPON STEEL CHEMICAL & MATERIAL CO., LTD.

Dates

Publication Date

20260506

Application Date

20240628

Claims (5)

1. A carbon material for a catalyst carrier of a solid polymer fuel cell, the carbon material comprising porous activated carbon black satisfying the following requirements (A) and (B): (A) a BET specific surface area S BET determined by BET analysis of a nitrogen gas adsorption isotherm is from 400 to 1200 m 2 /g, and (B) a ratio ΔV fin /ΔV ini is from 0.75 to 0.95 in a case in which a difference between an amount (mL/g) of mercury absorption at a mercury intrusion pressure of 10 MPa and an amount (mL/g) of mercury absorption at a mercury intrusion pressure of 100 MPa after pressurization of the porous activated carbon black at a pressure of 100 MPa with a mold in a mercury porosimetry method, and such a difference before pressurization of the porous activated carbon black at a pressure of 100 MPa with the mold, are respectively defined as ΔV fin and ΔV ini .
2. The carbon material for a catalyst carrier of a solid polymer fuel cell according to claim 1, wherein at least one of the following requirements (C) or (D) is further satisfied: (C) the ΔV ini is from 0.80 mL to 1.50 mL/g, and (D) an intensity ratio I D /I G is from 1.40 to 2.20 in a case in which an intensity in a D band of from 1300 to 1360 cm -1 is designated as I D and an intensity in a G band of from 1560 to 1620 cm -1 is designated as I G in a Raman spectrum obtained by Raman spectrometry.
3. A catalyst layer for a solid polymer fuel cell, the catalyst layer comprising the carbon material for a catalyst carrier of a solid polymer fuel cell according to claim 1 or claim 2.
4. A fuel cell comprising the catalyst layer for a solid polymer fuel cell according to claim 3.
5. The fuel cell according to claim 4, wherein the catalyst layer for a solid polymer fuel cell is a catalyst layer on a cathode side.

Description

Technical Field The present disclosure relates to a carbon material for a catalyst carrier of a solid polymer fuel cell, a catalyst layer for a solid polymer fuel cell, and a fuel cell. Background Art A solid polymer fuel cell which is one of fuel batteries includes paired catalyst layers placed on both surfaces of a solid polymer electrolyte membrane, a gas diffusion layer placed outside each of the catalyst layers, and a separator placed outside such each gas diffusion layer. One catalyst layer of the paired catalyst layers serves as an anode of the solid polymer fuel cell and the other catalyst layer serves as a cathode of the solid polymer fuel cell. In a usual solid polymer fuel cell, plural unit cells each having the above constituent components are stacked in order to obtain the desired output. A fuel gas such as hydrogen is introduced into the separator on the anode side. The gas diffusion layer on the anode side allows fuel to be diffused and then introduced into the anode. The anode includes a catalyst component, a catalyst carrier carrying a catalyst for a fuel cell, and an electrolyte material having proton conductivity. Hereinafter, a catalyst component promoting an electricity generation reaction (oxidation reaction or reduction reaction described later) in a fuel cell is also referred to as "catalyst for a fuel cell". The catalyst carrier is often constituted from a porous carbon material. The oxidation reaction of the fuel gas occurs to generate protons and electrons on the catalyst for a fuel cell. For example, in a case in which the fuel gas is a hydrogen gas, the following oxidation reaction occurs.         H2 → 2H+ + 2e- (E0 = 0 V) The protons generated in the oxidation reaction are introduced into the cathode through the electrolyte material (ionomer) in the anode and the solid polymer electrolyte membrane. The electrons are introduced into an external circuit through the catalyst carrier, the gas diffusion layer, and the separator. The electrons are worked in the external circuit, and then introduced into the separator on the cathode side. The electrons are then introduced into the cathode through the separator on the cathode side and the gas diffusion layer on the cathode side. The solid polymer electrolyte membrane is constituted from an electrolyte material having proton conductivity. The solid polymer electrolyte membrane introduces the protons generated in the oxidation reaction, into the cathode. An oxidizing gas such as an oxygen gas or air is introduced into the separator on the cathode side. The gas diffusion layer on the cathode side allows the oxidizing gas to be diffused and then introduced into the cathode. The cathode includes a catalyst for a fuel cell, a catalyst carrier carrying the catalyst for a fuel cell, and an electrolyte material having proton conductivity. The catalyst carrier is often constituted from a porous carbon material. The reduction reaction of the oxidizing gas occurs to generate water on the catalyst for a fuel cell. For example, in a case in which the oxidizing gas is an oxygen gas or air, the following reduction reaction occurs.         O2 + 4H+ + 4e- → 2H2O (E0 = 1.23 V) The water generated in the reduction reaction is discharged together with the unreacted oxidizing gas, outside the fuel cell. Thus, the solid polymer fuel cell generates electricity by use of the difference in free energy (difference in potential) generated along with the oxidation reaction of the fuel gas. In other words, the free energy generated in the oxidation reaction is converted to the work to be performed in the external circuit with the electrons. Meanwhile, porous carbon materials (hereinafter, also referred to as "carbon carriers") applicable to catalyst carriers of solid polymer fuel batteries have been studied and variously proposed. For example, Patent Literature 1 proposes "A membrane electrode assembly including a polymer electrolyte membrane, and paired electrode catalyst layers sandwiching the polymer electrolyte membrane, in which at least one of the paired electrode catalyst layers include a catalyst-carrying particle, a polymer electrolyte, and a fibrous substance having an average fiber diameter of from 10 nm to 300 nm, the mass of the fibrous substance is from 0.02 times to 1.0 time the mass of a carrier in the catalyst-carrying particle, and the mass of the polymer electrolyte is from 0.4 times to 1.0 time the mass of a carrier in the catalyst-carrying particle.". Patent Literature 2 proposes "A carbon material for a catalyst carrier of a solid polymer fuel cell, in which the carbon material is a porous carbon material having a three-dimensional dendritic structure three-dimensionally branched, the branch diameter is 81 nm or less, and the following (A) and (B) are simultaneously satisfied.". (A) The BET specific surface area SBET determined by BET analysis of a nitrogen gas adsorption isotherm is from 400 to 1500 m2/g.(B) A relationship between the mercu