KR101483282B1 - Method for manufacturing graphite coated composite bipolar plate of cell - Google Patents

Abstract

The present invention provides a method for manufacturing a graphite coated composite bipolar plate for a battery, which manufactures a composite bipolar plate by co-curing laminated carbon fiber composite material sheets and expanded graphite foils. According to the present invention, multiple carbon fiber composite material sheets and multiple expanded graphite foils are laminated alternately, and the carbon fiber composite material sheets and the expanded graphite foils are co-cured so that the expanded graphite foils are bonded to both sides of the laminated multiple carbon fiber composite material sheets. The expanded graphite foils are individually separated to form expanded graphite layers on both sides of the carbon fiber composite material sheets. Also, two expanded graphite foils are laminated between carbon fiber composite material sheets, a film is interposed between the two expanded graphite foils, and, then, the carbon fiber composite material sheets and two expanded graphite foils are co-cured. According to the present invention, the carbon fiber composite material sheets and the expanded graphite foils are alternately laminated, and the laminated carbon fiber composite material sheets and expanded graphite foils are co-cured to manufacture a composite bipolar plate, thereby improving the productivity and reducing the production costs. Furthermore, the expanded graphite layer is uniformly coated on the surface of the composite bipolar plate without a post-processing, thereby improving the quality.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing a graphite-coated composite material separator for a battery,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separator for a battery, and more particularly, to a separator for a battery, which comprises a carbon fiber composite material sheet and an expanded graphite foil which are co- To a method for producing a graphite-coated composite material separator for a battery.

Fuel cells are energy conversion devices that directly convert the chemical energy generated by the oxidation of fuel into electrical energy. Fuel cells have been developed in various forms and structures depending on the type of fuel used in the battery. Polymer Electrolyte Membrane Fuel Cell (PEMFC) uses a polymer membrane with hydrogen ion exchange properties as an electrolyte. Also, research and development of redox flow battery is being actively carried out as a secondary battery which is effective for storing renewable energy among various energy storage systems. A redox flow cell is an electrochemical storage device in which the active energy of an electrolyte is oxidized and reduced to charge and discharge the chemical energy of the electrolyte directly.

U.S. Patent No. 7,862,922 entitled " Polymer electrolyte membrane for a fuel cell and a fuel cell system comprising same "and U.S. Patent No. 7,901,836" Polymer electrolyte fuel cell " " The stack of the PEMFC disclosed in these patent documents basically consists of a plurality of unit cells and two end plates.

The PEMFC consists of an anode, a cathode, a polymer electrolyte membrane, two gas diffusion layers (GDLs), a plurality of gaskets and two separators have. The separator has low electrical resistance, high chemical resistance and mechanical properties, and low gas permeability to prevent leakage of hydrogen and oxygen. Also, the electrical contact resistance between two adjacent separator plates should be low. The material of the separator plate is composed of graphite, expanded carbon, stainless steel, or a polymer matrix with carbon particles and graphite particles added to a polymer matrix composite is used.

Redox flow cells are disclosed in many patent documents such as U.S. Patent No. 8,288,030, U.S. Patent No. 8,221,911, U.S. Patent No. 7,537,859. The redox flow battery is composed of a stack in which unit cells (single cells) are stacked in series, tanks in which different oxidation states are stored, and pumps that circulate the active material during charging and discharging have. The unit cells basically have a membrane, electrodes disposed on both sides of the membrane, and separators disposed on both sides of the electrodes. The separator is made of graphite.

Since the conventional graphite separator for a battery has a low contact resistance and a high electrical conductivity, a thin graphite plate must be formed by machining such as milling, resulting in high manufacturing cost, low productivity, This is a big problem. On the other hand, the expanded carbon separator and the polymer matrix-based fiber reinforced composite material have a disadvantage in that it is difficult to finely form a channel for fluid flow and the electric conductivity is lower than that of graphite. Polymer base fiber reinforced composite separator plates have a disadvantage of high electrical resistance. The stainless steel separator is high in productivity, but has a disadvantage of high contact resistance and corrosion.

The present invention is intended to solve various problems of the separator for a conventional battery. An object of the present invention is to provide a new graphite-coated composite material separator for a battery, which can be produced as a composite material separator by simultaneous curing of a laminated carbon fiber composite material sheet and an expanded graphite foil, And a method for manufacturing the same.

Another object of the present invention is to provide a method for producing a graphite-coated composite material separator for a battery in which an expanded graphite layer is uniformly coated.

According to an aspect of the present invention, there is provided a method of manufacturing a graphite-coated composite material separator for a battery. The method for manufacturing a graphite-coated composite material separator for a battery according to the present invention includes the steps of: alternately laminating a plurality of sheets of carbon fiber composite material and a plurality of expanded graphite foils; Simultaneously curing a plurality of carbon fiber composite material sheets and a plurality of expanded graphite foils such that a plurality of expanded graphite foils are bonded to both sides of a plurality of carbon fiber composite material sheets stacked; And separating each of the plurality of expanded graphite foils to form an expanded graphite layer on both sides of the plurality of carbon fiber composite material sheets.

According to another aspect of the present invention, there is provided a method of manufacturing a graphite-coated composite separator for a battery, comprising: alternately laminating a sheet of carbon fiber composite material and two expanded graphite foils; Interposing a film between the two expanded graphite foils; Simultaneously curing the carbon fiber composite material sheet and the two expanded graphite foils so that each of the two expanded graphite foils is bonded to both sides of the laminated carbon fiber composite material sheet; And separating the two expanded graphite foils to form an expanded graphite layer on both sides of the carbon fiber composite material sheet.

A method for manufacturing a graphite-coated composite material separator for a battery according to the present invention is a method for producing a composite sheet for graphite-coated composite material for batteries, comprising the steps of: alternately laminating a sheet of carbon fiber composite material and an expanded graphite foil and then curing the laminated sheet of carbon fiber composite material and the expanded graphite foil It can be manufactured as a separator to improve the productivity and reduce the production cost. In addition, there is a useful effect that the expanded graphite layer can be uniformly coated on the surface of the composite separator without post-processing to improve the quality.

1 is a perspective view showing a configuration of a graphite-coated composite material separator for a battery according to the present invention.
2 is a cross-sectional view illustrating simultaneous curing in the process for producing a graphite-coated composite separator for a battery according to the present invention.
3 is a cross-sectional view illustrating the coating of the expanded graphite layer in the method of manufacturing the graphite-coated composite separator for a battery according to the present invention.
4 is a cross-sectional view showing a structure in which a notch is formed in an expanded graphite foil in a method of manufacturing a graphite-coated composite separator for a battery according to the present invention.
5 is a cross-sectional view illustrating another embodiment of a method for manufacturing a graphite-coated composite material separator for a battery according to the present invention.

Other objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a method of manufacturing a graphite-coated composite separator for a battery according to the present invention will be described in detail with reference to the accompanying drawings.

1, a graphite-coated composite material separator for a battery 10 according to the present invention comprises a carbon fiber composite material sheet 20 and a carbon fiber composite material sheet 20 on the surface of the carbon fiber composite material sheet 20, And an expanded graphite layer (30) coated thereon. The graphite-coated composite material separator for a battery 10 according to the present invention comprises a plurality of carbon fiber composite material sheets 20 and a plurality of expanded graphite foils 40 alternately stacked and then co- ).

The carbon fiber composite material sheet 20 is prepared by impregnating a plurality of carbon fibers 22 into a polymer matrix 24 to form a sheet or a laminate. The carbon fibers 22 may be woven in plain weave, twill weave, or water weave. The carbon fiber composite material sheet 20 may have various shapes and structures such as a prepreg, a sheet molding compound, a chopped strand mat, and a woven roving. As the polymer matrix 24, a thermosetting resin or a thermoplastic resin can be used. The thermosetting resin may be a phenolic resin, an epoxy resin, a polyester resin, or the like. The thermoplastic resin may be polypropylene, polyethylene, polyvinyl chloride (PVC), or the like.

When the thermosetting resin is cured at a temperature of about 80 to 400 占 폚, the resin in the form of a monomer is cross-linked or the resin in the non-stage (B-stage) is once melted Is changed from a liquid to a solid by a crosslinking reaction. The curing of the thermoplastic resin is accomplished by completely melting the resin by the application of heat energy to fill the interface of the carbon fibers, and then to solid again when the temperature is lowered.

When natural graphite is hydrolyzed by adding sulfuric acid vapor or a mixture of sulfuric acid and nitric acid, it is washed and dried to give graphite oxide. When this graphite oxide is heated at 1,000 ° C. for a short time and compressed, it becomes an expanded graphite foil (40). The expanded graphite foil 40 is impermeable to gases and liquids, maintains elasticity and flexibility in the range of -200 to 1,650 DEG C, and has heat resistance. In addition, the expanded graphite foil 40 has stable characteristics for a long period of time at a high pressure and a chemical reagent, and has a characteristic of being easy to separate into several layers due to weak binding force between the respective graphite particles.

Referring to FIGS. 1 and 2, a mold 50 for simultaneous hardening of the composite material separation plate 10 includes a lower mold 52 and an upper mold 54. A plurality of carbon fiber composite material sheets 20 and a plurality of expanded graphite foils 40 are stacked alternately on the lower mold 52 in the mold opening state of the lower mold 52 and the upper mold 54. [ do. At this time, the carbon fiber composite material sheet 20-1 and the bottom metal mold 52, the top carbon fiber composite material sheet 20-n, and the top carbon fiber composite material sheet 20-1 among the stacked carbon fiber composite material sheets 20, And each of the expanded graphite foils 40 is interposed between the molds 54 as well.

Subsequently, when the stacking of the carbon fiber composite material sheets 20 and the expanded graphite foils 40 is completed, the worker presses the lower mold 52 and the upper mold 54, The upper mold 54 and the upper mold 54 are heated by heating means such as heater to form the carbon fiber composite material sheets 20 and the expanded graphite foils 40 by the lower mold 52 and the upper mold 54, Consolidate and cure. The consolidation and curing of the carbon fiber composite material sheets 20 and the expanded graphite foils 40 can be variously performed by autoclave molding or hot press molding. The autoclave molding is a method in which the carbon fiber composite material sheets 20 and the expanded graphite foils 40 are co-cured by applying pressure and heat to form the carbon fiber composite material sheets 20 in a vacuum state. Hot press molding is a method of simultaneously molding the carbon fiber composite material sheets 20 and the expanded graphite foils 40 by pressing the upper mold 54 provided with the heater.

3, when the carbon fiber composite material sheets 20 and the expanded graphite foils 40 are co-cured and the carbon fiber composite material sheets 20 are taken out from the mold 50, The surface of each of the material sheets 20 is coated with the expanded graphite layer 30 to produce the composite separator plate 10. [ That is, each of the expanded graphite foils 40 is bonded to the polymer matrix 24 at the time of simultaneous curing, and when the carbon fiber composite material sheets 20 are separated, the expanded graphite foils 40 are divided into two, The expanded graphite layer 30 is formed on both sides of each of the first and second layers 20.

2, the carbon fiber composite material sheet 20-1 and the lower mold 52, the uppermost carbon fiber composite material sheet 20-n, and the upper mold 54 are interposed Each of the expanded graphite foils 40 serves as a release agent so that the bottom and top carbon fiber composite material sheets 20-1 and 20-n from the lower and upper dies 52 and 54 are easily separated. Therefore, after the carbon fiber composite material sheets 20 and the expanded graphite foils 40 are co-cured, they can be easily taken out from the mold 50.

4, a notch 42 is formed along the edge of each of the expanded graphite foils 40 at the center of the edge of each of the expanded graphite foils 40. As shown in Fig. When separating the cured carbon fiber composite material sheet 20, the expanded graphite foils 40 are uniformly bisected with respect to the notches 42. Therefore, the surface of the expanded graphite layer 30 is uniformly formed without post-processing.

5 shows another embodiment of a method for producing a graphite-coated composite separator for a battery according to the present invention. Referring to FIG. 5, two expanded graphite foils 40 are interposed between the carbon fiber composite material sheets 20 stacked. A film 60 is interposed between the two expanded graphite foils 40. The film 60 may be composed of polytetrafluorethylene (PTFE), polypropylene, polyethylene, a metal thin film, or the like.

When the carbon fiber composite material sheets 20 are separated after the co-curing of the carbon fiber composite material sheets 20 and the expanded graphite foils 40, the expanded graphite foils 40 are formed on both sides of the carbon fiber composite material sheets 20, (40) are joined together to form an expanded graphite layer (30). At this time, the two expanded graphite foils 40 interposed between the two sheets of carbon fiber composite material 20 are easily separated by the film 60 and bonded to the respective sheets of carbon fiber composite material 20 . Since the expanded graphite foils 40 are easily separated by the film 60 to form the uniform expanded graphite layer 30, the productivity and quality of the composite separator 10 can be improved.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

10: graphite-coated composite material separation plate 20: carbon fiber composite material sheet
30: expanded graphite layer 40: expanded graphite foil
42: notch 52: lower mold
54: Upper mold 60: Film

Claims (5)

Alternately stacking a plurality of sheets of carbon fiber composite material and a plurality of expanded graphite foils;
Simultaneously curing the plurality of sheets of carbon fiber composite material and the plurality of expanded graphite foils so that the plurality of expanded graphite foils are bonded to both surfaces of the plurality of carbon fiber composite material sheets stacked;
And separating each of the plurality of expanded graphite foils to form an expanded graphite layer on both sides of the plurality of sheets of carbon fiber composite material. The method according to claim 1,
Further comprising forming a notch at the center of each of the plurality of expanded graphite foils for natures of each of the plurality of expanded graphite foils. 3. The method according to claim 1 or 2,
Wherein the plurality of sheets of carbon fiber composite material and the plurality of expanded graphite foils are alternately stacked between a lower mold and an upper mold, and the plurality of sheets of carbon fiber composite material and the plurality of expanded graphite foils are stacked alternately between the lower mold and the upper mold, And the expanded graphite foil is interposed between the top carbon fiber composite material sheet and the upper metal mold among the plurality of carbon fiber composite material sheets. Alternately stacking one sheet of carbon fiber composite material and two expanded graphite foils;
Interposing a film between the two expanded graphite foils;
Simultaneously curing the carbon fiber composite material sheet and the two expanded graphite foils so that the two expanded graphite foils are bonded to both sides of the laminated carbon fiber composite material sheet;
And separating the two expanded graphite foils to form an expanded graphite layer on both surfaces of the carbon fiber composite material sheet. 5. The method of claim 4,
Wherein the one sheet of the carbon fiber composite material and the two expanded graphite foils are alternately stacked between the lower mold and the upper mold, and the sheet of the lower carbon fiber composite material among the sheets of the laminated carbon fiber composite material, A method for manufacturing a graphite-coated composite material separation plate for a battery, comprising interposing a graphite foil and interposing an expanded graphite foil between a top carbon fiber composite material sheet and a top metal mold among the stacked carbon fiber composite material sheets.

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