Process for preparing a fuel cell electrode substrate comprising carbon fibers

• US 4,506,028 A
• Filed: 12/17/1982
• Issued: 03/19/1985
• Est. Priority Date: 12/29/1981
• Status: Expired due to Term

• Current Assignee: Kureha Kagaku Kogyo Kabushiki Kaisha
• Original Assignee: Kureha Kagaku Kogyo Kabushiki Kaisha
• Inventors: Fukuda, Hiroyuki, Fujimaki, Hiroto, Yamanobe, Yoichiro, Kaji, Hisatsugu, Hiruta, Masaru, Ohmi, Sigeru
• Primary Examiner(s): Konopka, P. E.
• Application Number:
  US06/450,802
• Time in Patent Office: 823 Days
• Field of Search: 502/101, 502/418, 264/29.3, 264/29.5, 264/29.6, 264/29.7, 423/445, 423/447.3, 423/449, 429/40, 429/44
• US Class Current: 502/101
• CPC Class Codes: C04B 35/83 Carbon fibres in a carbon matrix
• CPC Class Codes: H01M 4/96 Carbon-based electrodes
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

An electrode substrate for a fuel cell having a high porosity, a good mechanical strength and electroconductivity and a sharp distribution of pore radii is prepared by a process comprising mixing 30 to 50% by weight of carbon fiber, 20 to 50% by weight of a binder and 20 to 50% by weight of an organic granule, press-shaping the resultant mixture, curing the shaped product and calcinating the cured product.

Claims

1. A process for preparing a fuel cell electrode substrate, comprising mixing (a) 30-50% by weight of carbon fibers having a diameter of 5-30μ

, a length of 0.05-2 mm and a linear carbonizing shrinkage on calcinating at 2,000°

C. of 0.1-3.0%, (b) 20-50% by weight of a carbonaceous resin binder having a carbonizing yield of 30-75% by weight, and (c) 20-50% by weight of an organic granule for controlling the production of pores in the product electrode substrate which has a carbonizing yield of at most 30% by weight and a diameter of 30-300μ and

does not evaporate nor melt nor flow at 100°

C., press-shaping the resultant mixture at a temperature of 100°

-200°

C. under a pressure of 5-100 kg/cm² for 2-60 minutes, curing the shaped product at about 150°

C. under about 0.5 kg/cm² for 0.5-10 hours per 1 mm in thickness of the shaped product, calcinating the cured product at a temperature of 1,000°

-3,000°

C. under an inert atmosphere for 0.5-5 hours and thereafter recovering an electrode substrate having a porosity of 40 to 85%, a bending strength of at least 80 kg/cm², a gas permeability of 100 to 1000 ml/cm².hr.mm.Aq and a bulk resistance of at most 5×

10^-2 Ω

cm.

2. The process of claim 1, wherein the weight ratio of the total amount of the carbon fibers and the organic granule to the amount of the binder is 1.5-4.0.

3. The process of claim 1, wherein the binder is a phenol resin or a mixture of a phenol resin and pitch.

4. The process of claim 1, wherein the organic granule is selected from the group consisting of polyvinyl alcohol, polyvinyl chloride, polyethylene, polypropylene, polystyrene and a mixture thereof.