JPS63281359A - Manufacture of conductive plastic electrode - Google Patents

Abstract

PURPOSE:To be able to manufacture an integrated conductive plastic electrode in conjugation of carbon fiber sheet to a definite part of carbon plastic plate in a simple measure by heat fusion bonding after providing a heat insulating layer at a part on one side or both sides of the carbon plastic plate, where no carbon fiber sheet is allocated. CONSTITUTION:At manufacture of an integrated electrode plate by heat fusion bonding of a carbon fiber sheet 3 with a carbon plastic plate 2, the carbon fiber sheet 3 is allocated only at a specific part on one side or both sides of the carbon plastic plate 2 and simultaneously a heat insulating layer 1 is provided at other parts, where no carbon fiber sheet 3 is allocated, on one side or both sides of the carbon plastic plate for heat fusion bonding. By the arrangement, avoiding penetration of adhesives, warp and shrinkage of the carbon plastic plate 2, and bite of the carbon fiber sheet 3 into the carbon plastic plate 2, a conductive plastic electrode, in which the carbon fiber sheet 3 is bonded with a specific part of the carbon plastic plate 2, is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a conductive plastic electrode,
More specifically, the present invention relates to a method for manufacturing conductive plastic electrodes used in new types of secondary batteries such as redox flow type and zinc-halogen type secondary batteries.

[Industrial application field]

The present invention relates to a method of manufacturing a conductive plastic electrode,
More specifically, the present invention relates to a method for manufacturing conductive plastic electrodes used in new types of secondary batteries such as redox flow type and zinc-halogen type secondary batteries.

[Conventional technology]

Although the international oil supply and demand situation has recently been easing, it is true that oil reserves are finite and are decreasing year by year. Furthermore, as seen in the accident at the Soviet Union's nuclear power plant, it is inevitable that the scale of nuclear power plants will be put on hold for safety reasons. On the other hand, summer power demand is increasing year by year, creating an imbalance in annual power consumption. Various research and development efforts have been made on new types of secondary battery storage systems that store off-peak power in advance in preparation for such peak times.

By the way, the electrodes conventionally used in this new type of secondary battery are a combination of bipolar plates made of conductive plates such as carbon plastic plates and carbon fiber sheets made of cloth, knit, or felt. was.

The main properties required for battery electrodes are conductivity, impermeability to electrolyte, flow resistance to circulating electrolyte, and mechanical strength. However, it has not been possible to find a material that satisfies these properties at the same time, so bipolar plates have to be impermeable to electrolyte and have mechanical strength, and have a large surface area for electron exchange (surface area) to improve conductivity. A conductive carbon fiber sheet was used. The current in a battery using these electrodes moves from one electrode to another (bipolar plate/carbon fiber sheet → carbon fiber sheet/bipolar plate), reducing the contact resistance that occurs between the two. Therefore, attempts have been made to bond and integrate a bipolar plate and a carbon fiber sheet.

For example, as in JP-A No. 59-87768, there is a method of joining the two with adhesive, or JP-A-59-2
A method of joining using hot press, etc., as in Japanese Patent No. 9385, has been proposed. However, with adhesive bonding, there is no need to worry about heat deformation of the carbon plastic sheets because the bonding can be performed at room temperature, but the problem is that the adhesive soaks into the carbon fiber sheets, impeding the flow of electrolyte and increasing pressure loss. was inviting. On the other hand, the method of pressure bonding using hot press is in principle an effective means for reducing the contact resistance between the carbon plastic plate and the carbon fiber sheet and improving the efficiency of the electrochemical reaction. However, with this method, if the matrix resin on the surface of the carbon plastic plate is not heated and melted uniformly to avoid temperature distribution, it may warp or shrink, causing changes in dimensions. The method used was to heat-seal and bond a carbon fiber sheet to the entire surface of the board, and then scrape off the unnecessary carbon fiber sheet.

However, this method has the disadvantage that the scraping operation takes a lot of time and that unevenness is likely to occur on the scraped surface.

Furthermore, the hot press method has the problem that the carbon fiber sheet temporarily bites into the carbon plastic due to the press pressure, making it difficult to accurately adjust the thickness of the carbon fiber sheet, and a solution to these problems has been desired.

[Problem that the invention seeks to solve]

The present invention solves the problems of the prior art, such as adhesive seepage, warpage and shrinkage of the carbon plastic plate, and the digging of the carbon fiber sheet into the carbon plastic plate, which was difficult to manufacture. The object of the present invention is to provide a method for manufacturing a conductive plastic electrode in which a carbon fiber sheet is bonded only to a predetermined portion of a carbon plastic plate.

[Means for solving problems]

The present inventors conducted research in order to solve the above-mentioned problems, and discovered a completely unprecedented manufacturing means and completed the present invention. That is, when manufacturing an electrode plate by integrating a carbon fiber sheet and a carbon plastic plate by heat fusion, the present invention disposes the carbon fiber sheet only on a predetermined portion of one or both sides of the carbon plastic plate, and
This method of manufacturing a conductive plastic electrode is characterized in that a heat insulating layer is provided on one or both sides of the carbon plastic plate other than the portion where the carbon fiber sheet is arranged, and then heat fusion bonding is performed.

The present invention will be explained in detail below.

First, the carbon fiber sheet referred to in the present invention is acrylic fiber,
Fibers such as rayon, lignin/poval, petroleum-based pinch, coal-based pitch, etc. are carbonized and surface activated at higher temperatures and processed into shapes such as cloth, knit, or felt.

Furthermore, the carbon plastic plate used in the present invention is a thermoplastic resin such as polyethylene, polypropylene, ethylene-propylene copolymer resin, polybutene, vinyl chloride resin, methylpentene polymer, fluorocarbon resin, carbon blank, graphite, etc. After kneading a conductive filler, it is formed into a plate shape using an extruder or the like, and preferably has a volume resistivity of 10Ω-ω or less and is impermeable to battery electrolyte. Point.

In the present invention, the surface temperature of such a carbon plastic plate is set within a temperature range from 10° C. or higher to the melting point of the matrix resin to 80° C. or lower, preferably 20° C. or higher than the melting point of the matrix resin.
From the above, the matrix resin in the surface layer is softened by maintaining the temperature within the melting point +70°C or less, and the carbon fiber sheet is placed only in the designated areas and crimped, then cooled and solidified to bond the two by heat fusion. It is something. Here, the predetermined portion refers to the portion on the carbon plastic plate where the carbon fiber sheet is placed, and this portion becomes the electrode of the battery.

The parts other than the predetermined parts, that is, the parts other than the part where the carbon fiber sheet is arranged, are the parts that become the joints with the manifold and the electrode frame for adjusting the flow rate of the electrolytic solution, and are places where the carbon fiber sheet should not be present. Therefore, a heat insulating layer is provided on one or both sides of the carbon plastic board other than the area where the carbon fiber sheet is placed, to shield the heat transmitted from the heat source to the carbon plastic, absorb the pressure applied to the carbon fiber sheet, and This serves to prevent the fiber sheet from breaking and digging into the carbon plastic plate, as well as to prevent warping due to heating in areas other than the carbon fiber sheet placement area.

In this case, the heat insulating layer referred to in the present invention refers to a layer whose thickness is desirably 0.5 to 0.95 times the thickness of the carbon fiber sheet. The thickness of the insulation layer is 0 of the thickness of the carbon fiber sheet.
．． If the thickness is less than 5, the carbon fiber sheet is likely to break due to the pressure bonding force, and if the thickness of the heat insulating layer is greater than 0.95 times, pressure will not be applied locally to the carbon fiber sheet, resulting in uneven bonding. Furthermore, the heat insulating layer has a melting point of the matrix resin of the carbon plastic plate subjected to heat fusion bonding +10°.
Compressive strength 20 kg/cm or more, thermal conductivity 1.0 kcal/m at temperatures from C or higher to melting point +80°C or lower
It is desirable to have physical properties of -h .degree. C. or less.

Specifically, ethylene propylene rubber, propylene oxide rubber, acrylic rubber, silicone rubber, vinylidene fluoride/propylene hexafluoride copolymer, vinylidene fluoride/ethylene trifluoride copolymer, silicon fluoride rubber, and fluorinated polyester. There are sheets made of rubber, etc. Alternatively, sheet materials such as wood, cork, foamed ceramics, and plastic may also be used. A material is selected from among these in consideration of the type of matrix resin, the amount of filler, etc.

Furthermore, by processing the surface of the heat insulating layer to have a smooth mirror surface, a textured pattern, ribbing, etc., it becomes easy to simplify battery assembly and improve the performance as an electrode, such as preventing electrolyte leakage.

Next, an example of an electrode obtained by heat-sealing and bonding a carbon fiber sheet to a predetermined portion of a carbon plastic plate according to the manufacturing method of the present invention is schematically shown. As shown in FIG. The surrounding area is left in the shape of a picture frame, the surrounding area is provided with heat insulation N1, and the carbon fiber sheet 3 is arranged on one or both sides of the central area, or two or more places on the carbon plastic plate 2 as shown in Fig. 2. Various cases are possible, such as placing it on one side or both sides.

Next, to explain these figures in more detail, Figures 1a and 1b are plan views when the carbon fiber sheet 3 is placed in the center of both sides of the carbon plastic plate 2, and the heat insulating layer l is provided around the periphery. and a sectional view, and FIG. 1C shows a state in which the laminate is pressed with a hot plate 4. In the state shown in FIG. 1C, the carbon fiber sheet 3 is compressed to the thickness of the heat insulating layer 1, but the press pressure is adjusted so that the thickness does not become less than the thickness of the heat insulating layer l. FIG. 1d shows a sectional view of a conductive plastic electrode formed by bonding a carbon fiber sheet to a predetermined portion of a carbon plastic plate.

Further, FIG. 2 shows a case where carbon fiber sheets are arranged on both sides of two places on a carbon plastic plate.

In this way, the placement position and number of carbon fiber sheets can be changed freely, so even if the electrode structure changes depending on the type and structure of the battery, it is possible to provide plastic electrodes that suit each type and structure. .

Further, as the heat fusion bonding method, any method such as a press, a roll, a heald conveyor, etc. that can be used for heat and pressure bonding can be used. In this case, the carbon plastic plate 2 may be a rectangular cut plate or a continuous sheet coming out of an extruder etc., and the heat insulating layer 1 may be a rectangular cut sheet or an endless sheet. It may be in the shape of a held con hair.

〔Example〕

Hereinafter, the effects of the present invention will be specifically explained based on Examples.

The carbon plastic plate contains 50 parts by weight, 17 parts by weight, and 33 parts by weight of polyethylene, carbon blank, and graphite, respectively.
After mixing parts by weight and kneading into pellets using a Banbury mixer, the pellets were made into pellets with a thickness of 1.5 mm by an extrusion molding machine.
It was molded to a thickness of 500 tl width x 600 h length. As the polyethylene, high-density polyethylene with a melting point of 130°C was used. The volume resistivity of the molded carbon plastic plate was 0.20Ω-ω.

As a carbon fiber sheet, the area electrical resistance is 0.22Ωcm”
, 2.61m thick cloth, area electrical resistance 0026Ω
cm2, thickness 3. Ol felt and area electrical resistance 0.
A cloth with a resistance of 22Ωcm2 and a thickness of 2.3mm was used. The size of each carbon fiber sheet is width 44011 x length 45
It was set as 0 Seal 1.

As shown in Table 1, the heat insulating layer has a thickness and material that corresponds to the thickness, strength, rigidity, etc. of the carbon fiber sheets to be joined.
For all other shapes, a rectangular sheet with a width of 520 mm and a length of 620 mm was used, with a rectangular hole of width 4411 mm x length 451 mm in the center.

Heat fusion was carried out using a 20-ton hot press equipped with a hot plate that circulates temperature-adjusting oil and capable of being finely driven by hydraulic pressure. In the heat fusion operation, first, the heat insulating layer, carbon fiber sheet, and carbon plastic plate are placed on a heat press as shown in Figure 1, and the temperature between the carbon fiber sheet and the carbon plastic plate is as shown in Table 1. After reaching the specified heating temperature,
It was preheated for 0 seconds and then pressurized for 30 seconds at the pressure shown in Table 1. The bonded plate was taken out from the heat press together with the heat insulating layer, sandwiched between wooden boards and cooled under a pressure of 1 kg/cm2 or less, and then the heat insulating layer was peeled off to obtain a carbon fiber sheet/carbon plastic integrated electrode plate.

The evaluation results of the obtained integrated electrode plate are shown in Table 1. Here, the carbon fiber sheet thickness refers to the thickness of the carbon fiber sheet exposed on the carbon plastic plate, and the carbon fiber broken layer refers to the amount of carbon fiber debris collected from the integrated electrode plate by a vacuum cleaner. Moreover, the bonding condition was determined by peeling off the carbon fiber sheet from the carbon plastic plate and visually judging whether it was good or bad.

In all of the integrated electrode plates of test numbers 1 to 4 manufactured by the method of the present invention, there was little deformation or breakage of the carbon fiber sheet.
In addition, the surface condition of the carbon plastic plate other than the carbon fiber sheet placement area was also very good, and no warping of the integrated electrode plate was observed.

On the other hand, the results of bonding under bonding conditions not based on the method of the present invention are shown in Table 1 as comparative examples in test numbers 5 and 6, and as reference examples in test numbers 7 and 8. No electrode plate was obtained.

〔Effect of the invention〕

According to the present invention, a conductive plastic electrode in which a carbon fiber sheet is bonded to a predetermined portion of a carbon plastic plate to be integrated can be manufactured by a simple means, and the industrial effect is remarkable.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic diagrams showing embodiments of electrodes obtained by the manufacturing method of the present invention. FIG. A plan view showing an embodiment, and a sectional view of a,
C is a cross-sectional view showing the state during crimping in b, and d is C
FIG. 2 is a cross-sectional view showing an aspect of the integrated electrode plate obtained in . 1: Heat insulation layer, 2: Temporary carbon plastic, 3: Carbon fiber sheet, 4: Heat plate.

Claims (2)

[Claims] (1) When manufacturing an electrode plate by integrating a carbon fiber sheet and a carbon plastic plate by heat fusion, the carbon fiber sheet is placed only on a predetermined portion of one or both sides of the carbon plastic plate, and the carbon fiber sheet is A method for producing a conductive plastic electrode, which comprises providing a heat insulating layer on one or both sides of a carbon plastic plate other than the placement portion, and then heat-sealing and bonding. (2) The thickness of the heat insulation layer is 0.5 to the thickness of the carbon fiber sheet
Claim 1 characterized in that it is 0.95 times
2. Method for manufacturing a conductive plastic electrode as described in Section 1.