JP2023026145A - Separator and manufacturing method for the same - Google Patents

Abstract

To provide a separator with high conductivity capable of suppressing metal elution and a manufacturing method for the same.SOLUTION: A separator 1 for a power storage device includes a plate 2 including graphite, resin, and metal fibers. The plate 2 includes grooves 30, 32 as flow channels on its surface. The metallic fiber includes at least one of copper, titanium, and stainless steel. The manufacturing method for the same is also provided.SELECTED DRAWING: Figure 2A

Description

TECHNICAL FIELD The present invention relates to a separator and a manufacturing method thereof.

A fuel cell is a battery that extracts energy through the reaction of hydrogen and oxygen. Since water is produced by the reaction, the fuel cell is known as an environmentally friendly battery. In particular, polymer electrolyte fuel cells are capable of high output density and are compact and lightweight, so they are expected to be promising batteries for automobiles, communication devices, electronic devices, etc., and have been partially put to practical use. A fuel cell is a cell stack configured by stacking a plurality of cells. A plate-like member called a separator is arranged between the cells. The separator is a partition wall plate that separates adjacent hydrogen and oxygen passages, and plays a role in allowing hydrogen and oxygen to uniformly contact and flow over the entire surface of the ion exchange membrane. For this reason, the separator is formed with grooves that serve as flow paths.

Separators are roughly classified into metal material type and carbon material type from the viewpoint of their constituent materials. Stainless steel, aluminum or its alloys, or titanium or its alloys are generally used for metallic material-based separators. Separators made of metallic materials are excellent in workability and can be made thin due to the strength and ductility inherent in metals. However, the metallic material-based separator has a higher specific gravity than the later-described carbon material-based separator, which is contrary to weight reduction of the fuel cell. Furthermore, metallic material-based separators have the drawback of having low corrosion resistance and forming a passive film depending on the material. Corrosion or passivation films of metal materials are not preferable because they lead to an increase in the electrical resistance of the separator. In order to improve the corrosion resistance of a separator made of a metal material, coating a precious metal by plating or sputtering leads to an increase in cost. A method of forming a portion with a photoresist film is known (see Patent Document 1).

On the other hand, carbon material-based separators have the advantage of having a smaller specific gravity and superior corrosion resistance than metal material-based separators. However, carbon material-based separators are inferior in workability and mechanical strength. There is also a demand for a further reduction in electric resistance (that is, a further increase in conductivity). As a method for improving the mechanical strength, for example, a separator in which graphite particles are dispersed in a thermoplastic resin is known (see Patent Document 2).

JP 2011-090937 A JP 2006-294407 A

Such a carbon material-based separator is effective in further increasing the conductivity by containing a metal material. However, in a carbon separator containing a metal material, the metal may be ionized and eluted under the influence of corrosive substances such as strong acid generated in the operating environment of the fuel cell.

An object of the present invention is to provide a highly conductive separator capable of suppressing metal elution, and a method for producing the same.

(1) A separator according to one embodiment for achieving the above object is a separator for an electricity storage device comprising a plate containing graphite, a resin, and a metal fiber, the plate having a surface on which flow is allowed to flow. With grooves as channels, said metal fibers are made of at least one of copper, titanium and stainless steel.
(2) In the separator according to another embodiment, preferably, the metal fiber may be contained in an amount of 40 parts by mass or more and 1000 parts by mass or less with respect to 100 parts by mass of the resin.
(3) A separator according to another embodiment is preferably a layer formed on both surfaces in the thickness direction of the plate including the groove and a surface of the plate other than the groove, A barrier layer having better gas barrier properties than the plate may be further provided.
(4) In the separator according to another embodiment, preferably, the barrier layer may be a film-like coating layer different from the plate.
(5) In the separator according to another embodiment, preferably, the barrier layer may be a filling layer in which resin or rubber fills between particles or fibers constituting the plate.
(6) In the separator according to another embodiment, the barrier layer may preferably include the filling layer and a film-like coating layer different from the plate.
(7) In a separator according to another embodiment, preferably the barrier layer contains at least one of polyetheretherketone and polyphenylene sulfide.
(8) In the separator according to another embodiment, preferably, the resin forming the plate and the resin forming the barrier layer may be the same type of thermoplastic resin.
(9) In the separator according to another embodiment, preferably, at least one of the resin forming the plate and the resin forming the barrier layer is mainly made of polyphenylene sulfide.
(10) A separator according to another embodiment may preferably be a fuel cell separator used between cells of a fuel cell.
(11) A method of manufacturing a separator according to an embodiment for achieving the above object is a method of manufacturing the separator according to any one of the above, wherein the graphite, the resin, and the metal are placed in a mold. and a molding step of arranging a molded article containing at least fibers, and a molding step of closing the mold with the molded article arranged.
(12) In the method for manufacturing a separator according to another embodiment, preferably, the mold has unevenness for transferring the groove on its inside, and the molding step includes forming the mold with the unevenness. may be used to mold the molded article and form the grooves.
(13) In the method for manufacturing a separator according to another embodiment, preferably, prior to the step of arranging the molded article, the molded article in a semi-cured state is made from a mixture containing at least the graphite, the resin, and the metal fiber. A pre-molding step for obtaining an object may be further included, and the molding object placement step may place the semi-cured molding object in the mold.
(14) In the method for manufacturing a separator according to another embodiment, preferably, prior to the step of arranging the molded article, a gas barrier is provided in the mold on one surface of the plate in the thickness direction from the plate. A first film placing step of placing a film for forming a barrier layer having excellent characteristics; and a second film placing step of placing on the molding object placed in the mold in the step of placing the molding object in the mold in the first film placing step The object to be molded is arranged on the arranged film, and in the molding step, the mold is closed while the object to be molded is sandwiched between the films, and the thickness of the plate is increased. The barrier layer may be formed on both surfaces.

ADVANTAGE OF THE INVENTION According to this invention, the separator which can suppress metal elution with high electroconductivity, and its manufacturing method can be provided.

FIG. 1 shows a plan view of a separator according to a first embodiment of the invention. FIG. 2A shows a cross-sectional view of the separator of FIG. 1 taken along line AA and an enlarged view of a portion B thereof, respectively. FIG. 2B shows enlarged views of variations a, b, and c of part C in part B of FIG. 2A. FIG. 3 shows an example of the flow of main steps of the separator manufacturing method according to the first embodiment. 4A and 4B show the states of each step of the manufacturing method of FIG. 3 in a cross-sectional view. FIG. 5 shows a cross-sectional view of a semi-cured pre-plate in which grooves are formed in a separator manufacturing method according to a modification. FIG. 6 shows a sectional view of the separator according to the second embodiment taken along line AA similar to FIG. 2A and an enlarged view of a part B thereof. FIG. 7 shows an example of the flow of main steps of the separator manufacturing method according to the second embodiment.

Next, embodiments of the present invention will be described with reference to the drawings. In addition, the embodiments described below do not limit the invention according to the claims, and all of the elements described in the embodiments and their combinations are essential to the solution of the present invention. not necessarily.

<First embodiment>
1. Separator FIG. 1 shows a plan view of a separator according to a first embodiment of the present invention. FIG. 2A shows a cross-sectional view of the separator of FIG. 1 taken along line AA and an enlarged view of a portion B thereof, respectively.

The separator 1 according to this embodiment is a substantially rectangular plate-like body in plan view. In a fuel cell, for example, the separator 1 is a plate-shaped body that sandwiches a membrane electrode assembly (MEA) in which both sides of an electrolyte membrane are sandwiched between an air electrode and a hydrogen electrode. In this embodiment, the separator 1 includes an anode-side separator arranged on the hydrogen electrode (also referred to as "anode electrode") side and a cathode-side separator arranged on the air electrode (also referred to as "cathode electrode") side. be construed broadly to include In this embodiment, the separator 1 is a carbon material-based separator. In addition, the separator 1 is not limited to fuel cells, and can also be used for plate-like members arranged between cells of other batteries (preferably storage batteries).

The separator 1 has through holes 11, 12, 21, and 22 passing through in its thickness direction. Through holes 11 and 21 are arranged on one end side of separator 1 . The through-hole 12 is arranged on the other end side of the separator 1 opposite to the one end side, facing the through-hole 21 when the separator 1 is viewed from above. The through hole 22 is arranged on the other end side opposite to the one end side of the separator 1 so as to face the through hole 11 when the separator 1 is viewed from above. A groove 30 as a flow path is formed on one surface side (surface side) of the separator 1 . A surface 31 other than the groove 30 is convex with respect to the groove 30 . A groove 32 as a flow path is formed on the opposite side (back side) of the separator 1 to the one side. The surface 31 other than the groove 32 is convex with respect to the groove 32 .

When the separator 1 is a cathode-side separator, the through hole 11 is an oxidizing gas supply port. The through hole 12 is an exhaust port for oxidizing gas. The through hole 21 is an outlet for hydrogen gas. The through hole 22 is a supply port for hydrogen gas. The oxidizing gas is, for example, air, but oxygen may also be used. A groove 30 on the surface side of the separator 1 is a channel for flowing an oxidizing gas. The groove 32 on the back side of the separator 1 is a channel for flowing cooling water. In FIG. 1, white arrows indicate the flow of the oxidizing gas.

When the separator 1 is an anode-side separator, the through-hole 11 is a hydrogen gas supply port. The through hole 12 is an outlet for hydrogen gas. The through hole 21 is an exhaust port for oxidizing gas. The through hole 22 is an oxidizing gas supply port. A groove 30 on the surface side of the separator 1 is a channel for flowing hydrogen gas. The groove 32 on the back side of the separator 1 is a channel for flowing cooling water.

Separator 1 comprises at least plate 2 . In this embodiment, the separator 1 preferably comprises a plate 2 and, optionally, a barrier layer 3 on both surfaces in the thickness direction of the plate 2 .

(plate)
The plate 2 is a plate containing graphite, resin, and metal fibers, and has grooves 30 and 32 as channels on the surface of the plate. The plate 2 is a molded body containing graphite, resin, and metal fibers, and has a fine structure in which graphite is dispersed in the resin and metal fibers that are solidified after being melted. The plate 2 may comprise graphite, resin and metal fibers, as well as fibers other than the resin. The fibers may be any kind of non-metallic fibers such as resin fibers, carbon fibers, ceramic fibers, etc., but are preferably resin fibers, more preferably aramid fibers. The fiber diameter of the aramid fiber is preferably 5-20 μm, more preferably 9-15 μm. The fiber length of the aramid fiber is preferably 1-15 mm, more preferably 3-9 mm. The fiber diameter and fiber length refer to the fiber diameter and fiber length measured from the field of view of 20 independent fibers selected under a microscope (optical microscope and scanning electron microscope are used depending on the size). When calculating the average fiber diameter or average fiber length, average the fiber diameter or fiber length of 20 pieces. The same applies to the following fiber diameter, fiber length, average fiber diameter and average fiber length. By adding fibers to the plate 2, the strength of the plate 2 can be increased. The area of the plate 2 in plan view is preferably 10-1000 cm ² , more preferably 100-750 cm ² . The thickness of the plate 2 is preferably 0.1-2.0 mm, more preferably 0.2-1.5 mm.

The resin forming the plate 2 is not particularly limited, but is preferably a thermoplastic resin. Resins more suitable for the plate 2 are resins with excellent heat resistance, specifically polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyamide (PA), polyetherketoneetherketoneketone ( PEKEKK), polyetherketone (PEK), liquid crystal polymer (LCP), polytetrafluoroethylene (PTFE), tetrafluoroethylene-ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), polyimide (PI), Examples include polyamideimide (PAI), polyethersulfone (PES), polyphenylsulfone (PPSU), polyetherimide (PEI) and polysulfone (PSU). Among these, PPS or PEEK is particularly suitable. Examples of PPS include M2888 and E2180 manufactured by Toray Industries, Inc., and FZ-2140 and FZ-6600 manufactured by Dainippon Ink and Chemicals.

The average particle diameter of the resin used before molding the plate 2 is preferably 1 μm or more and 300 μm or less, more preferably 5 μm or more and 150 μm or less, and even more preferably 10 μm or more and 100 μm or less. Here, the average particle size refers to a particle size measured by a laser diffraction/scattering particle size distribution measurement method. The method for measuring the average particle diameter hereafter is also the same.

The graphite forming the plate 2 may be artificial graphite, expanded graphite, natural graphite, or the like. Here, expanded graphite refers to graphite or a graphite intercalation compound in which the graphite layers are expanded by another material layer entering (= intercalation) a specific surface of a structure in which regular hexagonal planes of graphite (graphite) are stacked. Say. Examples of expanded graphite include BSP-60A (average particle size 60 μm) or EXP-50SM manufactured by Fuji Graphite Industry Co., Ltd. Examples of artificial graphite include 1707SJ (average particle size 125 μm) manufactured by Oriental Sangyo Co., Ltd. ), AT-No. 5S (average particle size 52 μm), AT-No. 10S (average particle size 26 μm), AT-No. 20S (average particle size 10 μm), or PAG, HAG manufactured by Nippon Graphite Industry Co., Ltd. As natural graphite, CNG-75N (average particle size 43 μm) manufactured by Fuji Graphite Industry Co., Ltd. or Nippon Graphite Industry Co., Ltd. CPB (flake-like graphite powder, average particle size 19 μm) manufactured by Kobayashi Pharmaceutical Co., Ltd. can be used. Moreover, the shape of the graphite particles is not particularly limited, and can be appropriately selected from the shape of flakes, scales, spheres, and the like. Furthermore, graphite may partially contain amorphous carbon.

The average particle size of the graphite used before molding the plate 2 is preferably 1 μm to 500 μm, more preferably 3 μm to 300 μm, even more preferably 10 μm to 150 μm.

Graphite and resin may be separately adjusted in particle size and then mixed and used for molding the plate 2. Alternatively, the graphite and the resin may be kneaded first, pulverized, adjusted in particle size, and used for molding the plate 2. can be used for When graphite and resin are kneaded and pulverized to adjust the particle size, the average particle size of the mixed powder is preferably 1 μm or more and 500 μm, more preferably 3 μm or more and 300 μm or less, and even more preferably 10 μm or more and 150 μm. It is below.

The mass ratio of graphite and resin constituting the plate 2 is graphite:resin=70 to 95 parts by mass:30 to 5 parts by mass. For example, the constituent material of the separator 1 can be obtained by mixing 5 parts by mass of resin with 70 parts by mass or more and 95 parts by mass or less of graphite. Also, for example, 30 parts by mass of resin can be mixed with graphite in the range of 70 parts by mass or more and 95 parts by mass or less in the same manner as the constituent material of the separator 1 . The separator 1 preferably contains more graphite than resin in mass ratio. A more preferable mass ratio of graphite to resin is 10 parts by mass of graphite, or 10.1 parts by mass or more and 20 parts by mass or less of graphite to 1 part by mass of resin. As described above, when the mass part of graphite is larger than the mass part of resin, the number of contact points between graphite particles increases compared to the conventional separator, and the electrical resistance of the separator 1 is lowered (that is, the conductivity is improved. higher). A representative sample of the separator 1 has a volume resistivity of 3 mΩ·cm or less.

The metal fibers forming the plate 2 are fibers made of at least one of copper, titanium, and stainless steel, that is, fibers made of copper, titanium, stainless steel, or alloys thereof. As the copper fiber, for example, metal fiber (variety: copper) manufactured by Nijigi Co., Ltd. (average fiber diameter: 52.08 μm, average fiber length: 1.88 mm) can be used. As the titanium fiber, for example, metal fiber (variety: titanium) manufactured by Nijigi Co., Ltd. (average fiber diameter: 51.82 μm, average fiber length: 1.72 mm) can be used. As the stainless steel fiber, for example, metal fiber (variety: SUS316L) (average fiber diameter: 32.23 μm, average fiber length: 1.29 mm) manufactured by Nijigi Co., Ltd. can be used. The fiber diameter of the metal fibers is preferably 5-80 μm, more preferably 20-60 μm. The fiber length of the metal fibers is preferably 0.5-3.5 mm, more preferably 1.5-2.5 mm.

By providing the plate 2 with metal fibers, the electrical conductivity increases, that is, the volume resistance value can be lowered. A representative sample of the separator 1 consisting of the plate 2 provided with such metal fibers has a volume resistivity of 1.8 mΩ·cm or less.

It is preferable that the metal fibers forming the plate 2 are contained in an amount of 40 parts by mass or more and 1000 parts by mass or less with respect to 100 parts by mass of the resin. The plate 2 contains 40 parts by mass or more of the metal fiber with respect to 100 parts by mass of the resin, so that the electrical resistance of the separator 1 can be made lower (that is, the electrical conductivity can be made higher). On the other hand, since the plate 2 contains 1000 parts by mass or less of the metal fiber with respect to 100 parts by mass of the resin, it is possible to suppress damage to the mold due to the metal fiber during the manufacture of the separator 1 .

(barrier layer)
The barrier layer 3 includes grooves 30 and 32 and a surface 31 of the plate 2 other than the grooves 30 and 32 in this embodiment, and covers at least the front and back surfaces of the plate 2, although this is not an essential configuration. are doing. That is, the barrier layer 3 covers both the front and back surfaces of the plate 2 including the inner surfaces of the grooves 30 and 32 . The barrier layer 3 is, for example, a film-like coating layer different from the plate 2, and includes a film 4 that is an example of a barrier layer that covers the front surface and a film 5 that is an example of a barrier layer that covers the back surface. It consists of separating or fusing the types. In this embodiment, the barrier layer 3 is divided into a film 4 and a film 5, which are attached to both sides of the plate 2 in the thickness direction. However, the barrier layer 3 may have a bag shape that encloses the outer surface of the plate 2 with the films 4 and 5 joined together.

FIG. 2B shows enlarged views of variations a, b, and c of part C in part B of FIG. 2A.

Mode a is a mode in which the surface of the plate 2 is preferably provided with a film mainly made of resin or rubber. In configuration a, the barrier layer 3 is a film-like covering layer F different from the plate 2 . Form b is a form in which a barrier layer 3 impregnated with resin or rubber is provided in the vicinity of the surface of the plate 2 . In form b, the barrier layer 3 is a filling layer M in which resin or rubber fills between the particles or fibers that make up the plate 2 . Furthermore, in form c, the barrier layer 3 comprises a filling layer M and a covering layer F. As shown in FIG. Thus, the barrier layer 3 preferably takes the form a, b or c. However, the barrier layer 3 may take any form other than the forms a, b, and c as long as it has better gas barrier properties than the plate 2 . "Gas barrier property" or "gas barrier performance" as used herein means the property of preventing gas permeation. Hereinafter, the barrier layer 3 of form a will be mainly described.

The barrier layer 3 is preferably resin or rubber. The main material of the barrier layer 3 is one or more of the above-described suitable resins that constitute the plate 2, and more preferably at least one of PEEK and PPS. Here, the “main material” means a material that accounts for more than 50 mass % of the barrier layer 3 . The main material may be, for example, 51% by mass, 60% by mass, 70% by mass, 80% by mass, 90% by mass, 95% by mass, or 100% by mass as long as it exceeds 50% by mass with respect to the mass of the barrier layer 3. .

The thickness of the barrier layer 3 is preferably 2 μm or more and 50 μm or less, more preferably 4 μm or more and 35 μm or less. When the thickness of the barrier layer 3 is 2 μm or more, further 4 μm or more, the gas barrier property of the separator 1 can be further increased and the strength (bending strength) can be increased, thereby improving ease of handling. On the other hand, if the thickness of the barrier layer 3 is set to 50 μm or less, further 35 μm or less, the volume resistance value of the separator 1 can be lowered (that is, the conductivity can be increased). In this embodiment, strength means bending strength measured according to JIS K7171.

The resin forming the plate 2 and the resin forming the barrier layer 3 may be the same type of thermoplastic resin. In this case, since the resin near the surface of the plate 2 and the barrier layer 3 covering the plate 2 can be partially integrated, the strength of the separator 1 can be further improved. The thermoplastic resin is preferably PEEK or PPS.

2. Method for Manufacturing Separator Next, a method for manufacturing a separator according to an embodiment of the present invention will be described.

The manufacturing method of the separator 1 (hereinafter also simply referred to as the “manufacturing method”) includes a molding placement step of placing a molding containing at least graphite, a resin, and a metal fiber in a mold; and a molding step of closing the mold in the arranged state to perform molding. Moreover, the method of manufacturing the separator 1 preferably further includes a pre-molding step of obtaining a semi-cured molding from a mixture containing at least graphite, resin, and metal fibers prior to the molding-object placement step. In the method for manufacturing the separator 1, preferably, prior to the object placement step, the film 4 is arranged in the mold in the first film placement step of placing the film 4 in the mold and the object placement step. and a second film placement step of placing the film 5 on the molded article. In the following embodiments, the method for manufacturing a separator is preferably a method for manufacturing a fuel cell separator used between cells of a fuel cell. Further, the separator 1 is preferably a carbon material-based separator. However, the separator 1 is not limited to the fuel cell, and can also be used as a plate-like member arranged between cells of other batteries (preferably storage batteries).

FIG. 3 shows an example of the flow of main steps of the separator manufacturing method according to the first embodiment. 4A and 4B show the states of each step of the manufacturing method of FIG. 3 in a cross-sectional view.

The separator 1 includes a mixture forming step (S100), a preforming step (S110), a first film placing step (S200), a molding object placing step (S210), a second film placing step (S220), It can be manufactured through a molding step (S230). S100 to S230 will be described in detail below with reference to FIGS. 3 and 4. FIG.

(1) Mixture forming step (S100)
This step is a step of forming a mixture containing at least graphite, resin, and metal fibers. Specifically, a slurry is prepared by mixing and dispersing graphite, resin, and metal fibers in water or an aqueous alcohol solution. In this step, a slurry may be produced by adding fibers other than the resin to the graphite, resin and metal fibers.

(2) Preforming step (S110)
This step is a step of obtaining a semi-cured molding from the mixture. Specifically, the mixture is formed into a wet sheet in which the liquid is filtered and separated by a sheet machine having a mesh structure, and the wet sheet is heated and pressed by a press machine. As a result, a semi-cured molding (hereinafter also referred to as a "pre-plate") can be obtained. The mixture forming step (S100) and the preforming step (S110) can be omitted if a plate containing at least graphite, resin, and metal fibers is not manufactured but can be obtained by a method such as purchase.

(3) First film placement step (S200)
This step is a step of placing the film 4 for forming the barrier layer 3 in the mold 60 . Specifically, a lower mold 40 that constitutes the mold 60 is prepared, and the film 4 is laid on the concave portion 41 of the lower mold 40 (see FIG. 4(a)). The lower mold 40 has unevennesses 42 on the inner bottom surface of the concave portion 41 that can transfer the grooves 32 .

(4) Molded object placement step (S210)
This step is a step of placing the pre-plate 70 , which is a semi-cured object to be molded, on the film 4 . Specifically, the pre-plate 70 is placed on the film 4 laid on the lower mold 40 (see FIG. 4(b)).

(5) Second film placement step (S220)
This step is a step of disposing the film 5 for forming the barrier layer 3 on the pre-plate 70 in the mold 60 after the molding object disposing step (S210). Specifically, the film 5 is placed on the pre-plate 70 placed in the recess 41 of the lower mold 40 (see FIG. 4(c)).

(6) Forming step (S230)
In this step, the mold 60 is closed while the pre-plate 70 is sandwiched between the films 4 and 5 for molding. Specifically, an upper mold 50 that constitutes the mold 60 is prepared, placed on the concave portion 41 side of the lower mold 40, and the lower mold 40 and the upper mold 50 are closed (Fig. 4(d), ( e)). The upper mold 50 has a recess 51 on the surface facing the recess 41 of the lower mold 40 . The concave portion 51 has an uneven surface 52 on its inner bottom surface on which the groove 30 can be transferred. After the mold 60 is clamped, the pre-plate 70 is molded by heating. As a result, the pre-plate 70 hardens to form the plate 2 . Further, grooves 30 and 32 covered with barrier layer 3 (film 4 and film 5) are formed by transferring unevenness 41 and 51 (see FIG. 4(f)).

After the molding step (S230), the mold 60 is opened and the separator 1 is completed. In the manufacturing method of the separator 1, either the first film placement step (S100) or the second film placement step (S120) may not be performed.

FIG. 5 shows a cross-sectional view of a semi-cured pre-plate in which grooves are formed in a separator manufacturing method according to a modification.

In this modification, instead of the pre-plate 70, the separator 1 is manufactured using pre-plates 70a having grooves formed on both surfaces in the thickness direction. Specifically, in the pre-forming step (S110), the pre-plate 70a having grooves formed on both surfaces in the thickness direction is obtained from the mixture formed in the mixture forming step (S100). More specifically, the mixture is formed into a wet sheet by filtering and separating the liquid with a mesh structure sheet machine, and the wet sheet is placed in a mold with unevenness on the inner bottom surface and heated with a press. pressurize while As a result, the pre-plate 70a having grooves formed on both surfaces in the thickness direction can be obtained. Then, in the molding object arranging step (S210), the pre-plate 70a is arranged on the film 4 so that the grooves of the pre-plate 70a are aligned with the irregularities 42 (see FIG. 5). After that, the unevenness 52 of the upper mold 50 is aligned with the groove of the preplate 70a, the upper mold 50 and the lower mold 40 are closed, and the mold 60 is clamped. After that, the forming step (S230) of the manufacturing method described above is performed to complete the separator 1 (see FIGS. 4(e) and 4(f)).

<Second embodiment>
Next, a second embodiment of the invention will be described. In the separator according to the second embodiment and the method for manufacturing the same, redundant descriptions of the parts common to the first embodiment are omitted, and the descriptions in the first embodiment are substituted.

1. Separator FIG. 6 shows a cross-sectional view of the separator according to the second embodiment taken along line AA similar to FIG. 2A and an enlarged view of a part B thereof.

A separator 1 a according to this embodiment comprises a plate 2 . Unlike the separator 1 according to the first embodiment, the separator 1a according to this embodiment does not have the barrier layer 3 (the films 4 and 5). The separator 1a is the same as the separator 1 except that the barrier layer 3 is not provided.

2. Method for Manufacturing Separator FIG. 7 shows an example of a flow of main steps of a method for manufacturing a separator according to the second embodiment.

The separator 1a includes a mixture forming step (S300) of forming a mixture containing at least graphite, a resin and metal fibers, a pre-molding step (S310) of obtaining a semi-cured molding from the mixture, and It includes a molding step (S400) of arranging the molding object in the mold, and a molding step (S410) of closing the mold with the molding object in the mold. The mixture forming step (S300) and the preforming step (S310) are common to the mixture forming step (S100) and the preforming step (S110). The object placement step (S400) is the same as the object placement step (S210) except that the film 4 is not placed in the mold 60. The forming step (S410) is the same as the forming step (S230) except that it is performed without the films 4 and 5 being placed. Therefore, here, a description that overlaps with the manufacturing method of the separator 1 according to the first embodiment described above will be omitted.

<Other embodiments>
As described above, the preferred embodiments of the present invention have been described, but the present invention is not limited to these and can be implemented in various modifications.

The grooves 30 of the separators 1 and 1a may be grooves forming flow paths other than flow paths for gas flow in directions indicated by white arrows in FIG. Also, the groove 32 may be a groove that forms a flow path of any type. For example, the groove 30 may be a groove that forms a linear flow path from one end to the other end of the separators 1 and 1a, and the groove 32 may be a groove that forms a linear flow path in a direction substantially perpendicular to the groove 30. good. Moreover, the separators 1 and 1a may not have at least one of the grooves 30 and 32 formed therein.

After the forming step, a trimming step for trimming excess areas of film 4 and/or film 5 may be performed.

The separator 1 has the barrier layer 3 on both surfaces in the thickness direction of the plate 2, but may have the barrier layer 3 only on one surface in the thickness direction. When forming the barrier layer 3 only on the one surface, the second film placement step (S220) or the first film placement step (S200) may be omitted.

The manufacturing method of the first embodiment is a method of manufacturing a fuel cell separator in which the barrier layer 3 is a layer of resin or rubber. It may be a manufacturing method of.

Next, examples of the present invention will be described in comparison with comparative examples. In addition, the present invention is not limited to the following examples.

1. Main raw materials of plates (1) Graphite Graphite powder, which is a constituent material of separator plates, is manufactured by Oriental Kogyo Co., Ltd., product number: 1707SJ (artificial graphite, average particle size: 125 μm) and by Oriental Kogyo Co., Ltd. : AT-No. Two types of graphite powder of 5S (artificial graphite, average particle size 52 μm) were used.
(2) Resin Powder of polyphenylene sulfide (PPS) was used as a resin to be a constituent material of the plates of the separator. As the PPS, PPS fine powder obtained by freeze-pulverizing flaky PPS powder of Torelina M2888 manufactured by Toray Industries, Inc. and adjusted to an average particle size of 50 μm was used.
(3) Aramid fiber The aramid fiber, which is the constituent material of the separator plate, is Technora T32PNW 3-12 (average fiber length 3.2 mm, average fiber diameter 18 μm) manufactured by Teijin Limited and Twaron manufactured by Teijin Limited. Two types of aramid fibers of (registered trademark) D8016 (average fiber length 0.8 mm) were used.
(4) Metal Fiber Copper fiber, titanium fiber, stainless steel fiber, and aluminum fiber were used as the metal fiber constituting the plate of the separator. Metal fiber (variety: copper) manufactured by Nijigi Co., Ltd. (average fiber length: 1.88 mm, average fiber diameter: 52.08 µm) was used as the copper fiber. As titanium fibers, metal fibers (variety: titanium) manufactured by Nijigi Co., Ltd. (average fiber length: 1.72 mm, average fiber diameter: 51.82 µm) were used. As the stainless steel fiber, metal fiber (variety: SUS316L) manufactured by Nijigi Co., Ltd. (average fiber length: 1.29 mm, average fiber diameter: 32.23 µm) was used. Metal fiber (variety: aluminum) manufactured by Nijigi Co., Ltd. (average fiber length: 1.73 mm, average fiber diameter: 61.83 µm) was used as the aluminum fiber.
(5) Metal Particles Copper particles, titanium particles and stainless steel particles were used as the metal particles constituting the plate of the separator. Cu-At-100 At2 (average particle diameter 97.98 μm) manufactured by Fukuda Metal Foil & Powder Co., Ltd. was used as the copper particles. TC-150 (average particle diameter 103.13 μm) manufactured by Toho Tech Co., Ltd. was used as the titanium particles. SUS316L powder (average particle size: 127.51 μm) manufactured by Nikola Co., Ltd. was used as the stainless steel particles.

2. A PPS film was used as the film for the film separator. As the PPS film, a 9 μm-thick film manufactured by Toray Industries, Inc. (product number: TORELINA 9-3071) was used.

3. Mold As a mold, a mold made of pre-hardened steel NAK80 manufactured by Daido Special Steel Co., Ltd. was used. A space (approximately 63 cm ³ ) capable of molding a separator is formed inside the closed mold. In addition, unevenness for forming the grooves of the separator is formed on the inner bottom of each of the upper and lower molds.

4. Evaluation method (1) Volume resistivity The volume resistivity of the separator was measured according to JIS K7194 using an apparatus (Loresta-GX T-700) manufactured by Mitsubishi Chemical Analytic Tech. A volume resistivity of 1.8 mΩ·cm or less was evaluated as pass B (“◯” in the table), and a volume resistivity of 0.5 mΩ·cm or less was evaluated as pass A (“⊚” in the table).
(2) Elution test In the elution test of the separator, the separator was placed in a flask, 400 ml of diluted sulfuric acid adjusted to pH 3 was added, the lid was placed, and the separator was immersed at 80°C for 10 days. The total amount of the eluate was acidolyzed into a solution, and quantitative analysis of the eluate was performed using an ICP analyzer. A metal ion concentration of 200 ppm or more is rejected (“x” in the table), 100 ppm or more and less than 200 ppm is passed C (“△” in the table), and 1 ppm or more and less than 100 ppm is passed B (“○” in the table). Less than 1 ppm was evaluated as pass A (“⊚” in the table). For example, in the case of titanium fibers, the ion concentration of eluted titanium was used as the measured value for the elution test. In the case of stainless steel fibers, the total concentration of iron, manganese, and other ions derived from the stainless steel fibers was used as the measurement value for the elution test. That is, in the elution test, depending on the type of metal fiber or metal particle, the total ion concentration of ions derived from the metal fiber or metal particle was used as the measurement value of the elution test.
(3) Comprehensive Evaluation A pass (“○” in the table) was evaluated when all of the characteristic value evaluations were evaluated as pass. Also, when at least one of the characteristic value evaluations was evaluated as unacceptable, it was evaluated as unacceptable (“x” in the table).

5. Production of Separator <Example>
(1) Example 1
Artificial graphite particles (product number: AT-No.5S) 977.8 parts by mass, PPS powder 100 parts by mass, aramid fiber (product number: T32PNW 3-12) 62.5 parts by mass, aramid fiber (product number: Twaron (registered trademark) D8016) 4.17 parts by mass and 244.4 parts by mass of titanium fiber were prepared and mixed and dispersed in water to prepare a slurry having a solid content of 1%. Here, 1 mass part corresponds to 0.1 g. The same applies to the description of the subsequent examples. This slurry was put into a filter having an inlet of 25 cm square, and a sheet-like wet sheet was formed as a residue obtained by filtration. The wet sheet is set in a press heated to 150° C. and pressurized and heated at a surface pressure of 13.4 MPa for about 20 minutes, and the wet sheet is dried to remove moisture, thereby producing artificial graphite particles and PPS particles. , aramid fibers, and titanium fibers dispersed therein and having a thickness of 2.0 mm and a basis weight of 1435 g/m ² .
Next, the pre-plate was applied to the concave portion inside the lower mold forming the split mold. Next, molding was performed by closing the upper mold and the lower mold, which constitute a split mold. Molding was carried out at a surface pressure of 13.4 MPa until the temperature of the mold rose to 340° C., and the surface pressure was raised to 53.7 MPa and held for 1 minute. Thereafter, the mold was pressurized and cooled to 30° C. while maintaining the pressure. After the molding was finished, the mold was opened, the molded body was taken out, and the production of the separator was completed. This separator has a single-layer structure consisting of a plate only. The separator was evaluated by the evaluation method described above.
(2) Example 2
A pre-plate was manufactured under the same conditions as in Example 1, except that 244.4 parts by mass of stainless steel fiber was used instead of 244.4 parts by mass of titanium fiber. Next, a PPS film was laid in the concave portion inside the lower mold constituting the split mold, and the pre-plate was provided on the film. Then, a PPS film was placed on the pre-plate. Next, molding was performed by closing the upper mold and the lower mold, which constitute a split mold. Molding was carried out at a surface pressure of 13.4 MPa until the temperature of the mold rose to 340° C., and the surface pressure was raised to 53.7 MPa and held for 1 minute. Thereafter, the mold was pressurized and cooled to 30° C. while maintaining the pressure. After the molding was finished, the mold was opened, the molded body was taken out, and the production of the separator was completed. This separator has a three-layer structure of film, plate and film. The separator was evaluated by the evaluation method described above.
(3) Example 3
A separator was manufactured and evaluated under the same conditions as in Example 1, except that 244.4 parts by mass of copper fiber was used instead of 244.4 parts by mass of titanium fiber. This separator has a single-layer structure consisting of a plate only.
(4) Example 4
Instead of 977.8 parts by mass of artificial graphite particles (product number: AT-No.5S) and 244.4 parts by mass of titanium fibers, 1102.22 parts by mass of artificial graphite particles (product number: AT-No.5S) and 120 parts by mass of titanium fibers A pre-plate was manufactured under the same conditions as in Example 1, except that parts by mass were used. Using the pre-plate, a separator was manufactured under the same conditions as in Example 2 and evaluated. This separator has a three-layer structure of film, plate and film.
(5) Example 5
Instead of 1102.22 parts by mass of artificial graphite particles (product number: AT-No.5S) and 120 parts by mass of titanium fibers, 742.22 parts by mass of artificial graphite particles (product number: AT-No.5S) and 480 parts by mass of titanium fibers A separator was produced and evaluated under the same conditions as in Example 4, except that the was used. This separator has a three-layer structure of film, plate and film.
(6) Example 6
Instead of 1102.22 parts by mass of artificial graphite particles (product number: AT-No.5S) and 120 parts by mass of titanium fibers, 1173.611 parts by mass of artificial graphite particles (product number: AT-No.5S) and 48 parts by mass of titanium fibers A separator was produced and evaluated under the same conditions as in Example 4, except that the was used. This separator has a three-layer structure of film, plate and film.
(7) Example 7
Instead of 1102.22 parts by mass of artificial graphite particles (product number: AT-No.5S) and 120 parts by mass of titanium fibers, 502.22 parts by mass of artificial graphite particles (product number: AT-No.5S) and 720 parts by mass of titanium fibers A separator was produced and evaluated under the same conditions as in Example 4, except that the was used. This separator has a three-layer structure of film, plate and film.
(8) Example 8
A separator was manufactured and evaluated under the same conditions as in Example 2 except that 122.2 parts by mass of titanium fiber and 122.2 parts by mass of stainless steel fiber were used instead of 244.4 parts by mass of stainless steel fiber. This separator has a three-layer structure of film, plate and film.

<Comparative example>
(1) Comparative Example 1
A separator was produced and evaluated under the same conditions as in Example 2 except that 244.4 parts by mass of copper particles were used instead of 244.4 parts by mass of stainless steel fibers. Comparative Example 1 was carried out using copper particles, which are an example of metal particles, instead of metal fibers. The separator of Comparative Example 1 has a three-layer structure of film, plate, and film.
(2) Comparative Example 2
Instead of 977.8 parts by mass of artificial graphite particles (product number: AT-No. 5S) and 244.4 parts by mass of stainless steel fibers, 977.8 parts by mass of artificial graphite particles (product number: 1707SJ) and artificial graphite particles (product number: A separator was manufactured and evaluated under the same conditions as in Example 2, except that 244.4 parts by mass of AT-No.5S) was used. Comparative Example 2 was carried out without using metal fibers. The separator of Comparative Example 2 has a single-layer structure consisting of only plates.
(3) Comparative Example 3
A separator was manufactured and evaluated under the same conditions as in Example 1, except that 244.4 parts by mass of aluminum fiber was used instead of 244.4 parts by mass of titanium fiber. Comparative Example 3 was carried out without using metal fibers made of at least one of copper, titanium, and stainless steel. The separator of Comparative Example 3 has a single-layer structure consisting of only plates.
(4) Comparative Example 4
A separator was manufactured and evaluated under the same conditions as in Example 2 except that 244.4 parts by mass of titanium particles were used instead of 244.4 parts by mass of stainless steel fibers. Comparative Example 4 was carried out using titanium particles, which are an example of metal particles, instead of metal fibers. The separator of Comparative Example 4 has a three-layer structure of film, plate, and film.
(5) Comparative Example 5
A separator was produced and evaluated under the same conditions as in Example 2, except that 244.4 parts by mass of stainless steel particles were used instead of 244.4 parts by mass of stainless steel fibers. Comparative Example 5 was carried out using stainless steel particles, which are an example of metal particles, instead of metal fibers. The separator of Comparative Example 5 has a three-layer structure of film, plate, and film.

7. Results Tables 1 to 4 show the manufacturing conditions and evaluation results of Examples and Comparative Examples.

For Comparative Examples 1-5, at least one of the volume resistivity and elution tests failed. On the other hand, all properties of Examples 1 to 8 passed.

From the above results, the comparison between Examples 1 to 8 and Comparative Example 2 confirmed the effect of including metal fibers as the constituent material of the plate. Also, from the comparison between Examples 2 and 4 to 8 and Comparative Examples 1, 4 and 5, the effect of including metal fibers instead of metal particles as the constituent material of the plate was confirmed. Further, from a comparison between Examples 1 to 8 and Comparative Example 3, the effect of including metal fibers made of at least one of copper, titanium, and stainless steel, instead of metal fibers made of other metals, as the constituent material of the plate is demonstrated. It could be confirmed. Further, from a comparison between Example 2 and Example 8, even when two or more types of metal fibers out of copper, titanium, and stainless steel are included, when one type of metal fiber out of copper, titanium, and stainless steel is included, A similar effect was confirmed.

The separator according to the present invention can be used as a separator between cells in a battery, especially a storage battery.

DESCRIPTION OF SYMBOLS 1, 1a... Separator, 2... Plate, 3... Barrier layer, 4, 5... Film, 30, 32... Groove, 31... Surface, 40... Lower mold (one component of the mold), 41, 51 ... concave portion, 42, 52 ... unevenness, 50 ... upper mold (one component of the mold), 60 ... mold, 70, 70a... Pre-plate (an example of the article to be molded), F... Coating layer, M... Filling layer.

Claims (14)

A separator for an electricity storage device comprising a plate containing graphite, resin, and metal fibers,
The plate has grooves as flow channels on its surface,
The separator, wherein the metal fibers are made of at least one of copper, titanium, and stainless steel. 2. The separator according to claim 1, wherein the metal fiber is contained in an amount of 40 parts by mass or more and 1000 parts by mass or less with respect to 100 parts by mass of the resin. Further comprising barrier layers formed on both surfaces in the thickness direction of the plate including the grooves and the surface of the plate other than the grooves, the barrier layers having gas barrier properties superior to those of the plate. 3. A separator according to claim 1 or 2. 4. The separator according to claim 3, wherein the barrier layer is a film-like covering layer different from the plate. 4. The separator according to claim 3, wherein said barrier layer is a filling layer in which resin or rubber is filled between particles or fibers constituting said plate. 6. The separator according to claim 5, wherein the barrier layer includes the filling layer and a film-like coating layer different from the plate. 7. The separator of any one of claims 3-6, wherein the barrier layer comprises at least one of polyetheretherketone and polyphenylene sulfide. 8. The separator according to any one of claims 3 to 7, wherein the resin forming the plate and the resin forming the barrier layer are the same type of thermoplastic resin. 9. The separator according to any one of claims 3 to 8, wherein at least one of the resin forming the plate and the resin forming the barrier layer is mainly composed of polyphenylene sulfide. 10. The separator according to any one of claims 1 to 9, which is a fuel cell separator used between cells of a fuel cell. A method for manufacturing the separator according to any one of claims 1 to 10,
A molded object arranging step of arranging a molded object containing at least the graphite, the resin, and the metal fiber in the mold;
A molding step in which the mold is closed and molding is performed in a state where the object to be molded is arranged;
A method of manufacturing a separator comprising: The mold has unevenness for transferring the groove on its inside,
12. The method of manufacturing a separator according to claim 11, wherein, in said molding step, said mold having said irregularities is used to mold said molded article and form said grooves. Further comprising a pre-molding step of obtaining the semi-cured molding object from a mixture containing at least the graphite, the resin, and the metal fiber, prior to the molding object arranging step,
13. The method of manufacturing a separator according to claim 11, wherein the molding object placing step places the molding object in a semi-cured state in the mold. A first film for forming a barrier layer having gas barrier properties superior to that of the plate on one surface of the plate in the thickness direction in the mold prior to the step of arranging the article to be molded. a placement process;
A second film arrangement in which a film for forming the barrier layer on the other surface of the plate in the thickness direction is placed on the article to be molded placed in the mold in the article to be molded placement step. process and
further comprising
The molding object arranging step places the molding object on the film placed in the mold in the first film arranging step,
In the molding step, molding is performed by closing the mold while the object to be molded is sandwiched between the films, and the barrier layer is formed on both surfaces of the plate in the thickness direction. A method for manufacturing the separator according to any one of claims 11 to 13.

Images