Nippon Pillar Packing Co., Ltd.

Toyota Jidosha Kabushiki Kaisha

Lignyte Co., Ltd.

Tsunemori Yoshida

Katsunori Sugita

Kazuhiko Otawa

Isamu Ide

Terumasa Yamamoto

Masanobu Nishikawa

Hisato Higuchi

Masahito Kaji

A separator for fuel cells is provided, which has excellent electrical conductivity, mechanical strength and gas impermeability. The separator is a molded article of a carbon-phenol resin molding compound obtained by reacting a phenol with an aldehyde in the presence of a catalyst, while mixing them with a carbon powder. As the catalyst, it is possible to use at least one selected from tertiary amines, carbonates, hydroxides and oxides of alkali metals or alkali earth metals. It is preferred that a content of nitrogen constituent in the molding compound is 0.3 wt % or less, and a carbon content in the molding compound is within a range of 75 wt % to 97 wt %.

Method of manufacturing separator for fuel cells

A carbon-phenol resin molding compound is provided, which is preferably used to obtain molded articles having high electrical and thermal conductivities as well as good mechanical strength. The resin molding compound is prepared by reacting a phenol with an aldehyde in the presence of a catalyst, while mixing them with a carbon powder such that a content of the carbon powder in the molding compound is 75 wt % or more. The catalyst is at least one selected from tertiary amines, carbonates, hydroxides and oxides of alkali metals or alkali earth metals.

Carbon-phenol resin molding compound

According to the invention, in a separator molded member (A) for a fuel cell which is produced by: loading a complex compound that is configured by bonding graphite powder by means of a thermosetting resin, into a mold (); and forming ribs () for forming gas passages by the resin molding process, the surfaces of the ribs () are alkali-treated by, for example, etching by using an alkaline solution, and graphite particles () which are flat and soft are exposed from the top surfaces of the ribs () which function as a contact surface with an electrode in the separator molded member (A), and resin defective portions () are formed between adjacent graphite particles (), whereby the contact area with an electrode is enlarged, so that the performance and efficiency of the fuel cell can be improved by remarkable lowering of the contact resistance.

Fuel cell separator

According to the invention, in a separator () for a fuel cell which is produced by: loading a complex compound that is configured by bonding graphite powder by means of a thermosetting resin, into a mold (); and forming ribs () for forming gas passages by the resin molding process, the surfaces of the ribs () are etched by an alkaline solution or alkali-treated, a surface resin layer which is formed on the surface of the separator () is removed away, and graphite particles showing a plate-like form are exposed from the surfaces of the ribs () which function as a contact surface with an electrode, whereby the contact resistance with an electrode is remarkably lowered, so that the performance and efficiency of the fuel cell can be improved.

Fuel cell separator and production method therefor

In a separator for a fuel cell and a method of producing a separator for a fuel cell according to the invention, bond-carbon is used in which composition ratios are set to 85 to 97 wt. % (preferably, 91 to 96 wt. %) of graphite powder having an average diameter in a range of 15 to 125 &mgr;m (preferably, 40 to 100 &mgr;m), and 3 to 15 wt. % (preferably, 4 to 9 wt. %) of a thermosetting resin. The compound is previously cold-molded into a shape similar to a final molded shape. The preliminary molded member is then placed in a mold, and a molding pressure in a range of 10 to 100 MPa (preferably, 20 to 50 MPa) is applied, thereby molding the member into a separator of the final shape. Therefore, a separator which is uniform and has a predetermined shape can be surely obtained while reducing the volume resistivity so as to ensure a good conductivity, whereby the performance of a fuel cell can be improved.

Separator for a fuel cell and a method of producing the same

In a separator for a fuel cell and a method of producing a separator for a fuel cell according to the invention, bondcarbon is used in which composition ratios are set to 60 to 90 wt. % (preferably, 70 to 87 wt. %) of graphite powder having an average diameter in a range of 15 to 125 &mgr;m (preferably, 40 to 100 &mgr;m), and 10 to 40 wt. % (preferably, 13 to 30 wt. %) of a thermosetting resin. The compound is previously cold-molded into a shape similar to a final molded shape. The preliminary molded member is then placed in a mold, and then molded into a separator of the final shape by applying a pressure of a range of 10 to 100 MPa. The surface roughness Ra of at least a portion of the separator contacting with an electrode is set to a range of 0.1 to 0.5 &mgr;m. According to this configuration, fluidity and moldability are excellent, the contact resistance can be set to a value lower than a requested value while ensuring strength sufficient for preventing the separator from suffering a damage such as a breakage due to vibrations or the like, and the low contact resistance can be stably maintained.

In a separator for a fuel cell according to the invention, a separator is formed by a molding a bondcarbon compound in which a composition ratio of graphite powder is set to 60 to 90%, and a composition ratio of a thermosetting resin is set to 10 to 40%, and at least a top end face of each of a number of ribs contacting the surface of an anode or a cathode is coated with a conductive film made of a material which is lower in specific resistance than the bondcarbon compound. According to this configuration, while excellent moldability and high productivity are ensured by the use of the bondcarbon compound containing a larger content of a resin, the contact resistance with respect to an electrode is lowered so that the conductivity of the whole can be improved, and predetermined performance of a fuel cell can be surely exerted.

Growing community of inventors

Kobe, Japan

Tsunemori Yoshida