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EP-4738482-A1 - CARBON MATERIAL FOR CATALYST CARRIER OF SOLID POLYMER FUEL CELL, CATALYST LAYER FOR SOLID POLYMER FUEL CELL, AND FUEL CELL

EP4738482A1EP 4738482 A1EP4738482 A1EP 4738482A1EP-4738482-A1

Abstract

A carbon material for a catalyst carrier of a solid polymer fuel cell, the carbon material including porous activated carbon black satisfying requirements (A) to (C): (A) a BET specific surface area is from 350 m 2 /g to 800 m 2 /g, (B) a value (VD 5-20 /VA 20 ) obtained by dividing a pore volume VD 5-20 exhibited by a pore having a pore size of from 5 nm to 20 nm, as determined by analysis of a nitrogen desorption isotherm with a DH (Dollimore-Heal) method, by a pore volume VA 20 exhibited by a pore having a pore size of 20 nm or less, as determined by analysis of a nitrogen adsorption isotherm with a DH method, is 0.35 or less, and (C) a temperature Td 10% at a reduction in weight of 10% in temperature rise at 10°C/min in an air atmosphere in thermogravimetry-differential thermal analysis is from 620 to 680°C.

Inventors

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

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), (B), and (C): (A) a BET specific surface area is from 350 m 2 /g to 800 m 2 /g, (B) a value (VD 5-20 /VA 20 ) obtained by dividing a pore volume VD 5-20 exhibited by a pore having a pore size of from 5 nm to 20 nm, as determined by analysis of a nitrogen desorption isotherm with a DH (Dollimore-Heal) method, by a pore volume VA 20 exhibited by a pore having a pore size of 20 nm or less, as determined by analysis of a nitrogen adsorption isotherm with a DH (Dollimore-Heal) method, is 0.35 or less, and (C) a temperature Td 10% at a reduction in weight of 10% in temperature rise at 10°C/min in an air atmosphere in thermogravimetry-differential thermal analysis (TG-DTA) is from 620 to 680°C.
  2. The carbon material for a catalyst carrier of a solid polymer fuel cell according to claim 1, wherein the pore volume VA 20 is from 0.36 to 0.90 mL/g.
  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. 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 reducing gas such as hydrogen is introduced into the separator on the anode side. The gas diffusion layer on the anode side allows the reducing gas 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 (ionomer) having proton conductivity. The catalyst carrier is often constituted from a carbon material. The oxidation reaction of the reducing gas occurs to generate protons and electrons on the catalyst component. For example, in a case in which the reducing 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 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 (generate electricity) in an 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 component, a catalyst carrier carrying the catalyst component, and an electrolyte material (ionomer) having proton conductivity. The catalyst carrier is often constituted from a carbon material. The reduction reaction of the oxidizing gas occurs to generate water on the catalyst component. 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 energy (difference in potential) between the oxidation reaction and the reduction reaction. In other words, the electrons generated in the oxidation reaction work in the external circuit. Meanwhile, use of porous carbon black in catalyst carriers has been conventionally proposed from the viewpoint of electricity generation performance of fuel batteries. Non-Patent Literature 1 reports that a catalytic metal carried in a pore formed inside of porous carbon black does not receive reaction inhibition (poisoning) due to covering with a co-existing ionomer and thus is highly active. Patent Literature 1 proposes porous carbon black having an average particle size of from 20 to 100 nm, in which the volume of a hole having a hole diameter of from 4 to 20 nm in the porous carbon black is from 0.23 to 0.78 cm3/g. Patent Literature 2 proposes a method including contacting a carbon black starting material and an oxidant in a fluidized bed, as a method including making carbon black porous to increase the surface area. Specifically, Patent Literature 2 proposes "A method of producing graphitized carbon high in surface area, the method including an oxidation step and a graphitization step of a starting carbon material in order to produce area graphitized carbon high in surface area, having a larger surface area by at least 100 m2/g than the surface area of the starting carbon material, in which the oxidation is performed before the graphitization, carbon high in surface area is produced by the oxidation, and the average hole volume of the graphitized carbon high in surface area is at least 1.32 cc/g". Conventionally, high crystallization of porous carbon black by firing has been proposed from the viewpoint of duration performance of a fuel cell. Patent Literature 3 proposes high-crystalline