JP2020139018A - Carbon member for cell and method of manufacturing the same, bipolar plate for redox flow cell, and separator for fuel cell - Google Patents

Abstract

To provide a carbon member for a cell capable of obtaining sufficient conductivity and strength, and improving conductivity in a thickness direction, a method of manufacturing the same, a bipolar plate for a redox flow cell, and a separator for a fuel cell.SOLUTION: A carbon member 1 for a cell comprises a conductive material 2, and a thermoplastic resin 3 where the conductive material 2 is a carbonaceous material containing at least any one of a squamous graphite particle, an artificial graphite particle, a spherical graphite particle, and a carbon fiber, the thermoplastic resin 3 is a polyolefin resin, or a polyphenylene sulfide resin, at least any one of the conductive material 2, and the thermoplastic resin 3 is subjected to plasma treatment, and both are mixed. Sufficient conductivity and flexure strength can be obtained since the conductive material 2 and the thermoplastic resin 3 are subjected to plasma treatment to improve compatibility and decrease a void between the conductive material 2 and the thermoplastic resin 3.SELECTED DRAWING: Figure 1

Description

The present invention relates to a carbon member for a battery used in a redox flow battery, a fuel cell, etc., a method for manufacturing the carbon member, a bipolar plate for the redox flow battery, and a separator for a fuel cell.

A carbon member for a battery is used for a bipolar plate for a redox flow battery and a separator for a fuel cell. Although not shown, this carbon member for a battery contains a conductive material such as graphite particles for ensuring conductivity and a thermoplastic resin for ensuring strength, and is used for manufacturing bipolar plates for redox flow batteries and separators for fuel cells. When used, it exhibits a certain level of bending strength so that it will not crack under a load during stacking or operation.

By the way, if it is desired to improve the bending strength of the bipolar plate for redox flow batteries and the separator for fuel cells, the content of the thermoplastic resin of the carbon member for the battery may be increased, but the content of the thermoplastic resin is simply increased. As a result, the content of the conductive material decreases, which leads to a decrease in conductivity. In view of this point, various inventions have been conventionally proposed in order to achieve both improvement of bending strength and maintenance of conductivity.

For example, Patent Document 1 includes a component (A) carbon nanotube, a component (B) an olefin polymer satisfying the following (1) to (3), and a component (C) a thermoplastic resin, and contains the component (A). The blending amount is 15 to 40% by mass with respect to 100% by mass of the total amount of the components (A) to (C), and the blending amount of the component (B) is 0.5 to 2 times the blending amount of the component (A). A resin composition is disclosed, (1) a weight average molecular weight (Mw) of 35,000 to 150,000, (2) a molecular weight distribution (Mw / Mn) of 3 or less, and (3) a softening point of 80 to 130 ° C. (See Patent Document 1).

Further, Patent Document 2 describes a composite of carbon fiber and thermoplastic resin on one or both sides of a conductive resin plate (1) made of a thermoplastic resin containing a particulate or discontinuous fibrous carbonaceous material. A separator for a fuel cell configured by laminating a CFRTP sheet (2) made of a material and integrating these by heat fusion. The CFRTP sheet (2) uses a thermoplastic resin as a matrix resin and is contained in the matrix resin. (Patent Document) shows a separator for a fuel cell, which is formed by arranging continuous carbon fibers in one direction or a plurality of directions and dispersing a granular or discontinuous fibrous carbon filler material in a resin (Patent Document). 2).

Japanese Unexamined Patent Publication No. 2016-41806 Japanese Unexamined Patent Publication No. 2016-119181

However, in the case of the resin composition of Patent Document 1, there is a problem that sufficient conductivity cannot be obtained because the content of carbon nanotubes is small. Further, in the case of the fuel cell separator of Patent Document 2, the continuous long filamentous carbon fibers of the CFRTP sheet are excellent in the conductivity in the surface direction of the fuel cell separator, but the conductivity in the thickness direction is improved. There is a problem that cannot be expected.

The present invention has been made in view of the above, and is a carbon member for a battery capable of obtaining sufficient conductivity and strength and improving conductivity in the thickness direction, a method for manufacturing the same, and a bipolar plate for a redox flow battery. , As well as a separator for a fuel cell.

In the present invention, in order to solve the above problems, it is composed of a conductive material and a thermoplastic resin.
It is characterized in that at least one of a conductive material and a thermoplastic resin is composed of a plasma-treated mixture.

The conductive material is preferably made of a carbonaceous material containing at least one of scaly graphite, artificial graphite, expanded graphite, spheroidal graphite, and carbon fiber.
The thermoplastic resin is preferably a polyolefin resin or a polyphenylene sulfide resin.

Further, the plasma treatment may be performed using at least one of oxygen gas, nitrogen gas, and argon gas.
Further, the plasma treatment may be performed using at least one of oxygen gas, nitrogen gas, and argon gas containing water.

Further, in the present invention, in order to solve the above problems, the method for manufacturing a carbon member for a battery according to any one of claims 1 to 5 is used.
A carbon member for a battery is formed by plasma-treating at least one of a conductive material and a thermoplastic resin, mixing them and filling them in a mold, then molding the mold and heat-compress molding. It is characterized by.

Further, in order to solve the above problems, the present invention is characterized in that a bipolar plate for a redox flow battery is formed by the carbon member for a battery according to any one of claims 1 to 5.
Further, in order to solve the above problems, the present invention is characterized in that the fuel cell separator is formed by the battery carbon member according to any one of claims 1 to 5.

Here, the conductive material in the claims may be in the form of powder particles, in the form of fibers, or the like. The expanded graphite of the conductive material includes both expanded graphite particles and expanded graphite particles that have been expanded. Further, the plasma treatment is carried out on the conductive material and the thermoplastic resin, the conductive material, or the thermoplastic resin. The plasma treatment should be carried out for at least 5 minutes, preferably 15 minutes or longer, and more preferably 20 minutes or longer. The gas for plasma treatment may or may not contain water. Further, the carbon member for a battery according to the present invention can be molded into a thin plate or a sheet, if necessary, in addition to powder.

According to the present invention, since at least one of the conductive material and the thermoplastic resin is plasma-treated, the compatibility between the conductive material and the thermoplastic resin is increased, and the thermoplastic resin easily flows between the conductive materials. .. As a result, the voids between the conductive material and the thermoplastic resin are reduced, and the conductivity and mechanical strength of the carbon member for the battery, the bipolar plate for the redox flow battery using the carbon member for the battery, and the separator for the fuel cell are improved. improves.

According to the present invention, since at least one of the conductive material and the thermoplastic resin is subjected to plasma treatment, sufficient conductivity and strength can be obtained, and the conductivity in the thickness direction can be improved. There is.

According to the invention of claim 2, when the conductive material is scaly graphite, excellent moldability and conductivity can be obtained. Further, when the conductive material is artificial graphite, excellent strength and purity can be obtained, and impurities such as metal can be reduced. In the case of expanded graphite, mixing with a thermoplastic resin becomes easy. Further, in the case of spheroidal graphite, suppression of orientation can be expected. Further, in the case of carbon fiber, excellent strength and conductivity can be obtained, and impurities such as metal can be reduced.

According to the invention of claim 3, when a polyolefin resin or a polyphenylene sulfide resin is used as the thermoplastic resin of the carbon member for the battery, the carbon member for the battery can be used for a bipolar plate for a redox flow battery or a fuel cell. When the separator is formed, it is possible to impart excellent moisture resistance, water resistance, and the like.
According to the invention of claim 5, it is possible to improve the hydrophilicity of the carbon member for a battery by performing plasma treatment using at least one of oxygen gas, nitrogen gas, and argon gas containing water. Become.

According to the invention of claim 6, during heat compression molding using a mold, the thermoplastic resin easily flows between the conductive materials, so that the gap between the conductive material and the thermoplastic resin is reduced, and the battery It can contribute to the improvement of conductivity and mechanical strength of the carbon member for use.
According to the invention of claim 7, sufficient conductivity and strength can be imparted to the bipolar plate for the redox flow battery, and the conductivity in the thickness direction of the bipolar plate for the redox flow battery can also be improved. ..

According to the invention of claim 8, sufficient conductivity and strength can be imparted to the fuel cell separator, and improvement in conductivity in the thickness direction of the fuel cell separator can be expected.

It is an enlarged explanatory view which shows typically the plasma-treated conductive material and the thermoplastic resin in embodiment of the carbon member for a battery which concerns on this invention. It is an enlarged explanatory view which shows typically the conductive material which has not been plasma-treated and the thermoplastic resin in embodiment of the carbon member for a battery which concerns on this invention. It is a perspective explanatory drawing which shows typically the embodiment of the bipolar plate for a redox flow battery which concerns on this invention. It is a plane explanatory view which shows typically the embodiment of the fuel cell separator which concerns on this invention. It is sectional drawing which shows typically the embodiment of the separator for a fuel cell which concerns on this invention.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the battery carbon member 1 in the present embodiment contains a fine conductive material 2 and a thermoplastic resin 3. The conductive material 2 and the thermoplastic resin 3 are plasma-treated mixtures, and are used as materials for a bipolar plate for a redox flow battery and a separator for a fuel cell.

The conductive material 2 and the thermoplastic resin 3 of the carbon member 1 for a battery contain a larger amount of the conductive material 2 than the thermoplastic resin 3 in terms of mass ratio. For example, when the conductive material 2 is 100 parts by mass, 300 parts by mass, 500 parts by mass, 800 parts by mass, and 1000 parts by mass, the thermoplastic resin 3 is mixed by blending 100 parts by mass.

The conductive material 2 includes scaly graphite particles that can be expected to have excellent moldability and conductivity, artificial graphite particles having excellent strength and purity, expanded graphite particles that are easier to mix with the thermoplastic resin 3 than scaly graphite particles, and suppression of orientation. It is composed of promising spheroidal graphite particles and a carbonaceous material containing at least one of lightweight carbon fibers having excellent strength and conductivity. These are not particularly limited as long as they are carbonaceous materials, but from the viewpoint of reliably eliminating metal impurities, at least one of artificial graphite particles and carbon fibers is optimal.

When the conductive material 2 is various graphite particles, the average particle size of the various graphite particles is 10 μm or more and 150 μm or less, preferably 15 μm or more and 140 μm or less, from the viewpoint of obtaining excellent mixability, moldability, conductivity, and practicality. The optimum size is 22 μm or more and 130 μm or less. Specific examples of scaly graphite particles include CB-150 [manufactured by Nippon Graphite Industry Co., Ltd .: product name] having an average particle diameter of 30 μm, and specific artificial graphite particles include PAG having an average particle diameter of 25 μm. -5 [manufactured by Nippon Graphite Industry Co., Ltd .: product name] and PAG-120 [manufactured by Nippon Graphite Industry Co., Ltd .: product name] having an average particle size of 130 μm can be mentioned.

Specific examples of expanded graphite particles include expanded graphite particles having an average particle diameter of 22 μm [manufactured by Fuji Graphite Industry Co., Ltd .: product name BSP-20], and specific spheroidal graphite particles include average. CGB-20 [manufactured by Nippon Graphite Industry Co., Ltd .: product name] having a particle size of 22 μm is applicable.

When the conductive material 2 is carbon fiber, the average fiber length is 0.03 mm or more and 9 mm or less, preferably 0.04 mm or more and 8.5 mm or less in order to obtain excellent strength and conductivity and improve dispersibility during manufacturing. , More preferably, a milled fiber of 0.05 mm or more and 8 mm or less, or a chop fiber is optimal. Specific examples of the carbon fiber include HT M800 [manufactured by Teijin Limited: product name] having an average fiber length of 160 μm.

As the thermoplastic resin 3, a polyolefin-based resin that can be easily molded at a relatively low temperature (160 to 170 ° C.) or a polyphenylene sulfide-based resin having a high melting point and excellent heat resistance and chemical resistance is selected and used. The surface of the conductive material 2 is coated or filled between the conductive materials 2. The shape of the thermoplastic resin 3 does not particularly matter whether it is in the form of particles, powder, or fibers. Specific examples of the polyolefin-based resin include inexpensive polypropylene (PP) resin manufactured by Prime Polymer Co., Ltd., which has excellent water resistance, and examples of the polyphenylene sulfide-based resin include polyphenylene sulfide (PPS) manufactured by Toray Co., Ltd., which has excellent water resistance. ) Resin is applicable.

In the above configuration, when manufacturing the carbon member 1 for a battery, first, a predetermined amount of the conductive material 2 and the thermoplastic resin 3 are prepared and mixed to prepare a powder mixture, and this mixture is dedicated. It is housed in a container and set in a plasma processing device, a gas for plasma processing is introduced into the plasma region between the high voltage electrodes of this plasma processing device, and high-density plasma treatment is performed to increase the compatibility and adhesion of the mixture. Let me. Specifically, after activating by introducing a gas for plasma treatment, the mixture is sprayed with an air flow on the lower mixture to reform the surface, thereby increasing the compatibility between the conductive material 2 of the mixture and the thermoplastic resin 3. Increases adhesion.

The plasma processing apparatus may be an atmospheric pressure plasma processing apparatus capable of plasma processing in an atmospheric pressure atmosphere at room temperature, or a vacuum plasma processing apparatus capable of plasma processing in a vacuum atmosphere. However, an atmospheric pressure plasma processing device that does not require depressurization and can be mass-produced even with a small facility is preferable.

When plasma treatment is performed by the atmospheric pressure plasma processing apparatus, a large amount of the conductive material 2 and the thermoplastic resin 3 of the mixture can be treated by one plasma treatment, and improvement in mass productivity can be expected. In this case, from the viewpoint of obtaining sufficient conductivity and mechanical strength, plasma treatment may be performed for at least 5 minutes or longer, preferably 30 minutes or longer. As the atmospheric pressure plasma processing apparatus, for example, S5000-BM [manufactured by Kai Semiconductor Co., Ltd .: product name] or the like can be used.

On the other hand, when plasma processing is performed by the vacuum plasma processing apparatus, the conductive material 2 and the thermoplastic resin 3 of the mixture can be stably plasma-processed in a relatively short time, and the redox flow is performed by the carbon member 1 for the battery. When molding a bipolar plate for a battery or a separator for a fuel cell, the mechanical strength can be improved. In this case, in order to obtain sufficient conductivity and mechanical strength, plasma treatment may be performed for at least 5 minutes or longer, preferably 15 minutes or longer, and more preferably 20 minutes or longer. As the vacuum plasma processing apparatus, for example, YHS-DφS [manufactured by Kai Semiconductor Co., Ltd .: product name] or the like can be used.

The gas for plasma treatment is not particularly limited, but at least one of oxygen gas, inert nitrogen gas, and high value-added inert argon gas is selected. When it is desired to improve the hydrophilicity of this gas, at least one of oxygen gas containing water vapor as water vapor, nitrogen gas, and argon gas is adopted.

When plasma processing is performed with the vacuum plasma processing device YHS-DφS [manufactured by Kaoru Semiconductor Co., Ltd .: product name], bubbling is performed with pure water kept at 70 ° C., and oxygen gas containing water vapor is used as a gas for plasma processing. Adjust the gas flow rate of oxygen gas so that the pressure becomes 90 Pa, set the output of the vacuum plasma processing device to 60 W, set the chamber angle of the vacuum plasma processing device to 10 °, and stir the mixture at a rotation speed of 10 rpm for the processing time. It can be processed in 30 minutes.

When the mixture is plasma-treated and the compatibility between the conductive material 2 and the thermoplastic resin 3 of the mixture is increased, the powder mixture is taken out from the plasma processing device, the plasma-treated mixture is filled in an opened mold, and the mold is formed. The carbon member 1 for a battery can be molded by molding and heat compression molding.

When filling the mold with the mixture, instead of immediately filling the mold with the plasma-treated mixture in the mold-opened mold, the plasma-treated mixture is put into a solution obtained by diluting the silane coupling agent to a constant concentration with a solvent. The mechanical strength of the carbon member 1 for a battery can be improved by filling the mold with an open mold after stirring and drying. In this regard, even if the mixture that has not been plasma-treated is simply added to a solution obtained by diluting the silane coupling agent to a constant concentration with a solvent, stirred, dried, and then filled in a mold, the number of surface functional groups is increased. Since it is scarce, it cannot be expected that the mechanical strength of the carbon member 1 for a battery will be improved. However, if the plasma-treated mixture is added, stirred, dried and filled in a mold, the mechanical strength can be greatly improved.

When the mixture is heat-compressed, the surfaces of the conductive material 2 and the thermoplastic resin 3 are functionalized (hydroxyl groups, carboxyl groups, amino groups, etc.), and the phases of the conductive material 2 and the thermoplastic resin 3 are phased with each other. Since the solubility is increased, the thermoplastic resin 3 is more likely to flow into the conductive material 2 than in the case where the plasma treatment is not performed (see FIG. 2) (see FIG. 1). As a result, the voids between the conductive material 2 and the thermoplastic resin 3 are reduced, and the mechanical strength of the carbon member 1 for the battery is improved.

According to the above, the conductive material 2 and the thermoplastic resin 3 are plasma-treated to improve compatibility and reduce the voids between the conductive material 2 and the thermoplastic resin 3, so that sufficient conductivity and bending strength are obtained. Can be obtained. Further, in addition to being expected to improve the conductivity in the XY direction, the conductivity in the Z direction (vertical direction and thickness direction in FIG. 1) can also be improved. Further, when the compatibility between the conductive material 2 and the thermoplastic resin 3 is increased, the value of the melt flow rate (MFR) indicating the fluidity is increased, so that the later molding processability can be remarkably improved.

Next, FIG. 3 shows a second embodiment of the present invention. In this case, the carbon member 1 for a battery manufactured by plasma treatment forms a planar rectangular redox flow battery bipolar plate 10. I am trying to do it.

The method for manufacturing the bipolar plate 10 for a redox flow battery is not particularly limited, but for example, a special mold or the like is filled with a carbon member 1 for a battery, heated and pressurized, and then cooled to be flat. A method of forming a rectangular thin plate can be mentioned.

Further, as another manufacturing method, a required number of composite sheets in which the conductive material 2 and the thermoplastic resin 3 are uniformly dispersed are obtained by setting the carbon member 1 for a battery in a dedicated mold of a press machine or the like and heating and pressurizing it. Molded, a composite sheet is set in the suction jig, another conductive material 2 is newly filled in the exposed surface, the suction jig is closed and the pressure is reduced to form the conductive molded body, and then molding is performed. A method of forming a thin plate by laminating another composite sheet on the exposed surface of the conductive molded body and heating and compressing it can be mentioned. Since the other parts are the same as those in the above embodiment, the description thereof will be omitted.

Also in this embodiment, the same action and effect as those in the above embodiment can be expected, and sufficient conductivity and strength can be imparted to the bipolar plate 10 for redox flow batteries, and the thickness of the bipolar plate 10 for redox flow batteries 10 can be imparted. It is clear that the conductivity in the direction can be improved. Further, since the value of the melt flow rate of the carbon member 1 for the battery is high, the molding process becomes really easy.

Next, FIGS. 4 and 5 show a third embodiment of the present invention. In this case, a fuel cell separator having a rectangular plane and a corrugated cross section is provided by the carbon member 1 for a battery manufactured by plasma treatment. 11 is molded.

The method for manufacturing the fuel cell separator 11 is not particularly limited, but for example, a thin plate is formed by filling a special mold or the like with the carbon member 1 for a battery, heating and pressurizing, and then cooling. There is a way to do it.

Further, as another manufacturing method, a required number of composite sheets in which the conductive material 2 and the thermoplastic resin 3 are uniformly dispersed are obtained by setting the carbon member 1 for a battery in a dedicated mold of a press machine or the like and heating and pressurizing it. Molded, a composite sheet is set in the suction jig, another conductive material 2 is newly filled in the exposed surface, the suction jig is closed and the pressure is reduced to form the conductive molded body, and then molding is performed. A method of forming a thin plate by laminating a composite sheet on an exposed portion of the conductive molded body and heating and compressing the composite sheet can be mentioned. Since the other parts are the same as those in the above embodiment, the description thereof will be omitted.

In this embodiment as well, the same action and effect as those in the above embodiment can be expected, and sufficient conductivity and strength can be imparted to the fuel cell separator 11, and the fuel cell separator 11 is conductive in the thickness direction. It is clear that can be improved. Further, since the carbon member 1 for the battery has a high melt flow rate value, the molding process becomes extremely easy.

In the above embodiment, the conductive material 2 and the thermoplastic resin 3 are plasma-treated, but the present invention is not limited to this. For example, only the conductive material 2 may be plasma-treated and mixed with the thermoplastic resin 3, or only the thermoplastic resin 3 may be plasma-treated and mixed with the conductive material 2.

Hereinafter, examples of the carbon member for batteries according to the present invention will be described together with comparative examples.
[Example 1]
First, in order to manufacture a carbon member for a battery, a mixture of powders is prepared by preparing and mixing 500 parts by mass of a conductive material and 100 parts by mass of a thermoplastic resin, and this mixture is set in an atmospheric pressure plasma processing apparatus. Then, after introducing nitrogen gas for plasma treatment into the plasma region between the high voltage electrodes of this atmospheric pressure plasma processing apparatus, plasma treatment was performed to increase the compatibility between the conductive material of the mixture and the thermoplastic resin.

As the conductive material, scaly graphite particles having an average particle diameter of 30 μm [manufactured by Nippon Graphite Industry Co., Ltd .: product name CB-150] were used. Further, as the thermoplastic resin, a polypropylene resin having an MFR of 15 g / 10 min [manufactured by Prime Polymer Co., Ltd .: product name PP J105P] was used. In the case of polypropylene resin, MFR is a value measured by applying a temperature of 230 ° C. and a load of 2.16 kg (JIS K7210). As the atmospheric pressure plasma processing apparatus, S5000-BM [manufactured by Kai Semiconductor Co., Ltd .: product name] was used.

When the mixture was set in the atmospheric pressure plasma processing apparatus, it was covered with a porous filter to prevent the mixture from being scattered by nitrogen gas. When plasma treatment is performed with the atmospheric pressure plasma processing apparatus, nitrogen gas containing water vapor is supplied at a flow rate of 30 L / 10 min, the output of the atmospheric pressure plasma processing apparatus is set to 100 W, and the mixture is stirred at a rotation speed of 70 rpm. However, the processing time was 30 minutes.

Next, the powder mixture is taken out from the atmospheric pressure plasma processing apparatus, the plasma-treated mixture is filled in a mold opened, and the mold is molded and heat-compressed to form a carbon member for a battery having a thickness of 2 mm. It was molded into a thin plate for testing. Since the thermoplastic resin of the mold is polypropylene resin, the mold was heat-compressed at 240 ° C.

After molding the carbon member for the battery, the bending strength, the volume resistance value in the surface direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are summarized in Table 1. The bending strength of the carbon member for batteries was determined by cutting out a strip-shaped test piece from the carbon member for batteries based on the JIS K7171 (ISO178) standard, and measuring and evaluating the bending strength using this test piece. The volumetric resistance value in the surface direction of the carbon member for the battery was measured by the four-terminal four-probe method. Specifically, a test piece having a size of 5 cm x 5 cm is cut out from a carbon member for a battery, and the volume resistivity value of the test piece is measured by a low resistivity meter [Mitsubishi Chemical Co., Ltd .: Product name: Loresta GP MCP. -T610] was used, and the measured value was taken as the surface resistivity value.

Regarding the volume resistance value in the thickness direction of the carbon member for batteries, first, a test piece having a size of 5 cm × 2.5 cm was cut out from the carbon member for batteries, and this test piece was sandwiched between glass tubes. The glass tube was a type in which the bent bottom of a φ1 cm glass U-shaped tube was cut and a holder with a screw hole was adhered to the cut bottom.

After sandwiching the test piece between the glass tubes, fix it with a screw so that mercury does not leak from between the test piece and both sides of the glass tube, inject a certain amount of mercury into both sides of the glass tube, and prepare with mercury. The resistance meter [manufactured by Hioki Denki Co., Ltd.] was connected with the prepared lead wire, the resistance value in the thickness direction was measured so as to conduct, and then converted to the volume resistance value in the thickness direction by the following formula.

Volume resistance value in the thickness direction [mΩ · cm] = Resistance value in the thickness direction [mΩ] × 0.5 [cm] × 0.5 [cm] × π ÷ Thickness of test piece [cm]
The resistance value in the thickness direction was obtained by cutting a 5 cm × 5 cm test piece whose volume resistance value in the surface direction was measured in half, measuring the resistance value in the thickness direction of this test piece, and converting it into a volume resistance value by the above formula. The average value was used.

[Example 2]
Basically the same as in Example 1, but the thermoplastic resin was changed to 500 parts by mass of a polypropylene resin [manufactured by Prime Polymer Co., Ltd .: product name PP H700] having an MFR of 9 g / 10 min. Other than that, the carbon member for the battery was molded in the same manner as in Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 1. Summarized.

[Example 3]
Basically the same as in Example 1, but the conductive material was changed to 500 parts by mass of artificial graphite particles [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-5] having an average particle diameter of 25 μm. Other than that, the carbon member for the battery was molded in the same manner as in Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 1. Summarized.

[Example 4]
Basically the same as in Example 1, but the conductive material was changed to 500 parts by mass of artificial graphite particles [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-120] having an average particle diameter of 130 μm. Other than that, the carbon member for the battery was molded in the same manner as in Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 1. Summarized.

[Example 5]
Basically the same as in Example 1, but the conductive material was changed to 500 parts by mass of expanded graphite particles [manufactured by Fuji Kokuen Industry Co., Ltd .: product name BSP-20] having an average particle diameter of 22 μm. Other than that, the carbon member for the battery was molded in the same manner as in Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 1. Summarized.

[Example 6]
Basically the same as in Example 1, but the conductive material was changed to 500 parts by mass of spheroidal graphite particles [manufactured by Nippon Graphite Industry Co., Ltd .: product name CGB-20] having an average particle diameter of 22 μm. Other than that, the carbon member for the battery was molded in the same manner as in Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 1. Described.

[Example 7]
Basically the same as in Example 1, but the conductive material was changed to 500 parts by mass of carbon fiber [manufactured by Teijin Limited: product name HT M800] having an average fiber length of 160 μm. Other than that, the carbon member for the battery was molded in the same manner as in Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 2. Described.

[Example 8]
Basically the same as in Example 1, but the conductive material is artificial graphite particles with an average particle diameter of 130 μm [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-120] 400 parts by mass, and carbon with an average fiber length of 160 μm. Fiber [Made by Teijin Limited: Product name HT M800] 100 parts by mass was changed to two types. Other than that, a carbon member for a battery was molded in the same manner as in Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 2. Described.

[Example 9]
Basically the same as in Example 1, but the conductive material was changed to 1000 parts by mass of artificial graphite particles [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-5] having an average particle diameter of 25 μm. Other than that, the carbon member for the battery was molded in the same manner as in Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 2. Described.

[Example 10]
A mixture of powders is prepared by preparing and mixing 350 parts by mass of a conductive material and 100 parts by mass of a thermoplastic resin, and this mixture is set in an atmospheric pressure plasma processing apparatus, and a high voltage electrode of this atmospheric pressure plasma processing apparatus is set. After introducing nitrogen gas for plasma treatment into the plasma region between them, plasma treatment was performed to increase the compatibility between the conductive material of the mixture and the thermoplastic resin. As the conductive material, artificial graphite particles having an average particle diameter of 25 μm [manufactured by Prime Polymer Co., Ltd .: product name PAG-5] were used. Further, as the thermoplastic resin, a polyphenylene sulfide resin having an MFR of 120 g / 10 min [manufactured by Toray Industries, Inc .: product name PPS E2180] was used. In the case of a polyphenylene sulfide resin, MFR is a value measured at a temperature of 316 ° C. and a load of 5 kg (JIS K7210).

When the mixture was set in the atmospheric pressure plasma processing apparatus, it was covered with a porous filter to prevent the mixture from being scattered by nitrogen gas. When plasma treatment is performed with the atmospheric pressure plasma processing apparatus, nitrogen gas containing water vapor is supplied at a flow rate of 30 L / 10 min, the output of the atmospheric pressure plasma processing apparatus is set to 100 W, and the mixture is stirred at a rotation speed of 70 rpm. However, the processing time was 30 minutes.

Next, the powder mixture is taken out from the atmospheric pressure plasma processing apparatus, the plasma-treated mixture is filled in a mold opened, and the mold is molded and heat-compressed to form a carbon member for a battery having a thickness of 2 mm. It was molded into a thin plate for testing. Since the thermoplastic resin of the mold is polypropylene resin, the mold was heat-compressed at 370 ° C.

After molding the carbon member for the battery, the bending strength, the volume resistance value in the surface direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured in the same manner as in Example 1, and the measurement results are summarized in Table 3.

[Example 11]
Basically the same as in Example 10, but the conductive material was changed to 350 parts by mass of artificial graphite particles [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-120] having an average particle diameter of 130 μm. Other than that, a carbon member for a battery was molded in the same manner as in Example 10, and the bending strength, the volume resistance value in the surface direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 3. Summarized.

[Example 12]
Basically the same as in Example 10, but the conductive material was changed to 350 parts by mass of carbon fiber [manufactured by Teijin Limited: product name HT M800] having an average fiber length of 160 μm. Other than that, a carbon member for a battery was molded in the same manner as in Example 10, and the bending strength, the volume resistance value in the surface direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 3. Described.

[Example 13]
Basically the same as in Example 10, but the conductive material was changed to 1000 parts by mass of artificial graphite particles [manufactured by Prime Polymer Co., Ltd .: product name PAG-5] having an average particle diameter of 25 μm. Further, as the thermoplastic resin, a polyphenylene sulfide resin having an MFR of 600 g / 10 min [manufactured by Toray Industries, Inc .: product name PPS M2888] was used. Other than that, a carbon member for a battery was molded in the same manner as in Example 10, and the bending strength, the volume resistance value in the surface direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 3. Described.

[Example 14]
In order to manufacture a carbon member for a battery, 500 parts by mass of a conductive material is set in an atmospheric pressure plasma processing apparatus, and nitrogen gas for plasma processing is introduced into a plasma region between high voltage electrodes of this atmospheric pressure plasma processing apparatus. Plasma treatment was performed in the same manner as in Example 1. The conductive material was 500 parts by mass of artificial graphite particles [manufactured by Prime Polymer Co., Ltd .: product name PAG-5] having an average particle diameter of 25 μm.

After plasma-treating the conductive material, a powder mixture was prepared by mixing with 100 parts by mass of the prepared thermoplastic resin not treated with plasma. As the thermoplastic resin, a polypropylene resin having an MFR of 15 g / 10 min [manufactured by Prime Polymer Co., Ltd .: product name PP J105P] was used.

Next, the mixture of powders was filled in an open mold, and the mold was compacted and heat-compressed to form a carbon member for a battery into a thin plate for testing having a thickness of 2 mm. Since the thermoplastic resin of the mold is polypropylene resin, the mold was heat-compressed at 240 ° C.
After molding the carbon member for the battery, the bending strength, the volume resistance value in the surface direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured in the same manner as in Example 1, and the measurement results are summarized in Table 4.

[Example 15]
Basically the same as in Example 14, but the conductive material was changed to 350 parts by mass of artificial graphite particles [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-120] having an average particle diameter of 130 μm. Further, the plasma-untreated thermoplastic resin was changed to a polyphenylene sulfide resin having an MFR of 120 g / 10 min [manufactured by Toray Industries, Inc .: product name PPS E2180]. In the case of a polyphenylene sulfide resin, MFR is a value measured at a temperature of 316 ° C. and a load of 5 kg (JIS K7210). Other than that, a carbon member for a battery was formed in the same manner as in Example 14, and the bending strength, the volume resistance value in the surface direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 4. Described.

[Example 16]
In order to manufacture a carbon member for a battery, 100 parts by mass of a thermoplastic resin is set in an atmospheric pressure plasma processing apparatus, and nitrogen gas for plasma processing is introduced into a plasma region between high voltage electrodes of this atmospheric pressure plasma processing apparatus. Plasma treatment was performed in the same manner as in Example 1. As the thermoplastic resin, a polypropylene resin having an MFR of 15 g / 10 min [manufactured by Prime Polymer Co., Ltd .: product name PP J105P] was used.

After plasma-treating the thermoplastic resin, a powder mixture was prepared by mixing with 500 parts by mass of the prepared conductive material not treated with plasma. As the conductive material, 500 parts by mass of artificial graphite particles [manufactured by Prime Polymer Co., Ltd .: product name PAG-5] having an average particle diameter of 25 μm were used.

Next, the mixture of powders was filled in an opened mold, and the mold was compacted and heat-compressed to form a carbon member for a battery into a thin plate for testing. After molding the carbon member for the battery, the bending strength, the volume resistance value in the surface direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured in the same manner as in Example 1, and the measurement results are summarized in Table 4.

[Example 17]
Basically the same as in Example 16, the plasma-untreated conductive material was changed to 350 parts by mass of artificial graphite particles [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-5] having an average particle diameter of 25 μm. Further, the thermoplastic resin was changed to a polyphenylene sulfide resin having an MFR of 120 g / 10 min [manufactured by Toray Industries, Inc .: product name PPS E2180]. Other than that, the carbon member for the battery was molded in the same manner as in Example 16, the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 4. Described.

[Example 18]
In order to manufacture a carbon member for a battery, 500 parts by mass of a conductive material and 100 parts by mass of a thermoplastic resin are prepared and mixed to prepare a powder mixture, and this mixture is set in an atmospheric pressure plasma processing apparatus. After introducing oxygen gas for plasma treatment into the plasma region between the high voltage electrodes of this atmospheric pressure plasma processing device, plasma treatment was performed to increase the compatibility between the conductive material of the mixture and the thermoplastic resin.

As the conductive material, artificial graphite particles having an average particle diameter of 25 μm [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-5] were used. Further, as the thermoplastic resin, a polypropylene resin having an MFR of 15 g / 10 min [manufactured by Prime Polymer Co., Ltd .: product name PP J105P] was used. In the case of polypropylene resin, MFR is a value measured by applying a temperature of 230 ° C. and a load of 2.16 kg (JIS K7210). As the atmospheric pressure plasma processing apparatus, S5000-BM [manufactured by Kai Semiconductor Co., Ltd .: product name] was used.

When the mixture was set in the atmospheric pressure plasma processing apparatus, it was covered with a porous filter to prevent the mixture from being scattered by oxygen gas. When plasma treatment is performed with the atmospheric pressure plasma processing apparatus, oxygen gas containing no water vapor is supplied at a flow rate of 30 L / 10 min, the output of the atmospheric pressure plasma processing apparatus is set to 100 W, and the mixture is stirred at a rotation speed of 70 rpm. The processing time was 30 minutes.

Other than that, the carbon member for the battery was formed into a thin plate for testing in the same manner as in Example 1, and after the carbon member for the battery was formed, the bending strength and the volume resistance value in the plane direction of the carbon member for the battery were formed in the same manner as in Example 1. , And the volume resistance value in the thickness direction were measured, respectively, and the measurement results are summarized in Table 5.

[Example 19]
Basically the same as in Example 18, but the conductive material was changed to 500 parts by mass of artificial graphite particles [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-120] having an average particle diameter of 130 μm. Other than that, the carbon member for the battery was molded in the same manner as in Example 18, the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 5. Described.

[Example 20]
Basically the same as in Example 18, but the conductive material was changed to 350 parts by mass of artificial graphite particles [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-5] having an average particle diameter of 25 μm. Further, the thermoplastic resin was changed to a polyphenylene sulfide resin having an MFR of 120 g / 10 min [manufactured by Toray Industries, Inc .: product name PPS E2180]. Other than that, the carbon member for the battery was molded in the same manner as in Example 18, the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 5. Described.

[Example 21]
Basically, the same as in Example 20, but the conductive material was changed to 350 parts by mass of artificial graphite particles [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-120] having an average particle diameter of 130 μm. Other than that, a carbon member for a battery was formed in the same manner as in Example 20, and the bending strength, the volume resistance value in the surface direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 5. Described.

[Comparative Example 1]
First, in order to manufacture a carbon member for a battery, a mixture of powders untreated with plasma was prepared by preparing and mixing 500 parts by mass of a conductive material and 100 parts by mass of a thermoplastic resin. As the conductive material, scaly graphite particles having an average particle diameter of 30 μm [manufactured by Nippon Graphite Industry Co., Ltd .: product name CB-150] were used. Further, as the thermoplastic resin, a polypropylene resin having an MFR of 15 g / 10 min [manufactured by Prime Polymer Co., Ltd .: product name PP J105P] was used.

Next, the untreated plasma mixture was filled in an open mold, and the mold was compacted and heat-compressed to form a carbon member for a battery into a thin plate for testing having a thickness of 2 mm. Since the thermoplastic resin of the mold is polypropylene resin, the mold was heat-compressed at 240 ° C.
After molding the carbon member for the battery, the bending strength, the volume resistance value in the surface direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured in the same manner as in Example 1, and the measurement results are summarized in Table 6.

[Comparative Example 2]
Basically the same as in Comparative Example 1, but the thermoplastic resin was changed to 500 parts by mass of a polypropylene resin [manufactured by Prime Polymer Co., Ltd .: product name PP H700] having an MFR of 9 g / 10 min. Other than that, the carbon member for the battery was molded in the same manner as in Comparative Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured and the measurement results are shown in Table 6. Summarized.

[Comparative Example 3]
Basically the same as in Comparative Example 1, but the conductive material was changed to 500 parts by mass of artificial graphite particles [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-5] having an average particle diameter of 25 μm. Other than that, the carbon member for the battery was molded in the same manner as in Comparative Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured and the measurement results are shown in Table 6. Summarized.

[Comparative Example 4]
Basically the same as in Comparative Example 1, but the conductive material was changed to 500 parts by mass of artificial graphite particles [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-120] having an average particle diameter of 130 μm. Other than that, the carbon member for the battery was molded in the same manner as in Comparative Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured and the measurement results are shown in Table 6. Summarized.

[Comparative Example 5]
Basically the same as in Comparative Example 1, but the conductive material was changed to 500 parts by mass of expanded graphite particles [manufactured by Fuji Kokuen Industry Co., Ltd .: product name BSP-20] having an average particle diameter of 22 μm. Other than that, the carbon member for the battery was molded in the same manner as in Comparative Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured and the measurement results are shown in Table 6. Summarized.

[Comparative Example 6]
Basically the same as in Comparative Example 1, but the conductive material was changed to 500 parts by mass of spheroidal graphite particles [manufactured by Nippon Graphite Industry Co., Ltd .: product name CGB-20] having an average particle diameter of 22 μm. Other than that, the carbon member for the battery was molded in the same manner as in Comparative Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured and the measurement results are shown in Table 6. Described.

[Comparative Example 7]
Basically the same as in Comparative Example 1, but the conductive material was changed to 500 parts by mass of carbon fiber [manufactured by Teijin Limited: product name HT M800] having an average fiber length of 160 μm. Other than that, the carbon member for the battery was molded in the same manner as in Comparative Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured and the measurement results are shown in Table 7. Described.

[Comparative Example 8]
Basically the same as in Comparative Example 1, but the conductive material is artificial graphite particles with an average particle diameter of 130 μm [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-120] 400 parts by mass, and carbon with an average fiber length of 160 μm. Fiber [Made by Teijin Limited: Product name HT M800] was changed to 100 parts by mass. Other than that, the carbon member for the battery was molded in the same manner as in Comparative Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured and the measurement results are shown in Table 7. Described.

[Comparative Example 9]
Basically the same as in Comparative Example 1, but the conductive material was changed to 1000 parts by mass of artificial graphite particles [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-5] having an average particle diameter of 25 μm. Other than that, the carbon member for the battery was molded in the same manner as in Comparative Example 1, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured and the measurement results are shown in Table 7. Described.

[Comparative Example 10]
A mixture of powders untreated with plasma was prepared by preparing and mixing 350 parts by mass of the conductive material and 100 parts by mass of the thermoplastic resin. As the conductive material, artificial graphite particles having an average particle diameter of 25 μm [manufactured by Prime Polymer Co., Ltd .: product name PAG-5] were used. Further, as the thermoplastic resin, a polyphenylene sulfide resin having an MFR of 120 g / 10 min [manufactured by Toray Industries, Inc .: product name PPS E2180] was used.

Next, the untreated plasma mixture was filled in an open mold, and the mold was compacted and heat-compressed to form a carbon member for a battery into a thin plate for testing having a thickness of 2 mm. After molding the carbon member for the battery, the bending strength, the volume resistance value in the surface direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured in the same manner as in Comparative Example 1, and the measurement results are summarized in Table 8.

[Comparative Example 11]
Basically the same as in Comparative Example 10, but the conductive material was changed to 350 parts by mass of artificial graphite particles [manufactured by Nippon Graphite Industry Co., Ltd .: product name PAG-120] having an average particle diameter of 130 μm. Other than that, a carbon member for a battery was molded in the same manner as in Comparative Example 10, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 8. Summarized.

[Comparative Example 12]
Basically the same as in Comparative Example 10, but the conductive material was changed to 350 parts by mass of carbon fiber [manufactured by Teijin Limited: product name HT M800] having an average fiber length of 160 μm. Other than that, a carbon member for a battery was molded in the same manner as in Comparative Example 10, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 8. Described.

[Comparative Example 13]
Basically the same as in Comparative Example 10, but the conductive material was changed to 1000 parts by mass of artificial graphite particles [manufactured by Prime Polymer Co., Ltd .: product name PAG-5] having an average particle diameter of 25 μm. Further, as the thermoplastic resin, a polyphenylene sulfide resin having an MFR of 600 g / 10 min [manufactured by Toray Industries, Inc .: product name PPS M2888] was used. Other than that, a carbon member for a battery was molded in the same manner as in Comparative Example 10, and the bending strength, the volume resistance value in the plane direction, and the volume resistance value in the thickness direction of the carbon member for the battery were measured, and the measurement results are shown in Table 8. Described.

[Rating]
In the case of each embodiment, at least one of the conductive material and the thermoplastic resin of the mixture is plasma-treated to increase the compatibility between them, so that the bending strength of the carbon member for the battery is improved and the excellent surface is obtained. The directional volume resistance value and the thickness surface direction volume resistance value could be obtained.

On the other hand, in the case of each comparative example, since both the conductive material and the thermoplastic resin of the mixture are not plasma-treated, the bending strength of the carbon member for the battery cannot be sufficiently improved as compared with the examples. there were.

The carbon member for a battery and its manufacturing method, the bipolar plate for a redox flow battery, and the separator for a fuel cell according to the present invention are used in the field of manufacturing a bipolar plate for a redox flow battery and a separator for a fuel cell.

1 Carbon member for battery 2 Conductive material 3 Thermoplastic resin 10 Bipolar plate for redox flow battery 11 Separator for fuel cell

Claims (8)

A carbon member for a battery made of a conductive material and a thermoplastic resin, wherein at least one of the conductive material and the thermoplastic resin is made of a plasma-treated mixture. The carbon member for a battery according to claim 1, wherein the conductive material is a carbonaceous material containing at least one of scaly graphite, artificial graphite, expanded graphite, spheroidal graphite, and carbon fiber. The carbon member for a battery according to claim 1 or 2, wherein the thermoplastic resin is a polyolefin resin or a polyphenylene sulfide resin. The carbon member for a battery according to claim 1, 2 or 3, wherein the plasma treatment is performed using at least one of oxygen gas, nitrogen gas, and argon gas. The carbon member for a battery according to claim 1, 2 or 3, wherein the plasma treatment is performed using at least one of oxygen gas, nitrogen gas, and argon gas containing water. The method for manufacturing a carbon member for a battery according to any one of claims 1 to 5, wherein at least one of a conductive material and a thermoplastic resin is plasma-treated, mixed and filled in a mold. A method for manufacturing a carbon member for a battery, which comprises molding a carbon member for a battery by molding a mold and heating and compression molding. A bipolar plate for a redox flow battery, which is formed of the carbon member for a battery according to any one of claims 1 to 5. A separator for a fuel cell, which is formed of the carbon member for a battery according to any one of claims 1 to 5.

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