Abstract:
A separator for a fuel battery comprising a conductive collector portion and a manifold portion. The collector portion is electrically conductive and includes channels for flowing reactive gas through the channels. The manifold portion includes gas introduction holes connected to the channels of the collector portion, and surrounds a circumferential edge portion of the collector portion to be integrated with the collector portion. The collector portion contains a resin binder, and the manifold portion contains a composition different from that of the collector portion.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a separator for various kinds of fuel batteries. 
     2. Description of the Related Art 
     An apparatus which uses hydrogen, fossil fuel, or the like, as fuel for directly converting chemical reaction energy generated in an oxidation reaction of the fuel into electric energy is known. This apparatus is generally called a fuel battery. 
     There are several kinds of fuel batteries. A fuel battery called a solid polymer type is known as one of these kinds of fuel batteries. As shown in FIG. 5, the solid polymer type fuel battery  100  has a structure in which a large number of cells are connected in series or in parallel. Each of the cells has a structure fin which a positive electrode  10 , an electrolyte  11  of a sold polymer, a negative electrode  12  and a separator  101  are laminated successively. Further, generally, supporting power collectors  13  are interposed between the electrodes  10  and the separators  101  and between the electrodes  12  and the separators  101 . 
     Each of the separators  101  has channels (grooves)  104  formed in both surfaces. Fuel gas or oxidizer gas is supplied to the respective channels  104  through fuel gas introduction holes  101   a  and oxidizer gas introduction holes  101   b . Further, the separator  101  has cooling water introduction holes  101   c  to form a structure in which cooling water is made to flow through the holes  101   c.    
     The operation of a basic fuel battery  100  is as follows. Incidentally, description will be made with attention paid to one cell in order to simplify the description. 
     In the operation, fuel gas to be oxidized, such as hydrogen, or the like, is supplied to the negative electrode  12  whereas oxidizer gas, such as oxygen, air, or the like, is supplied to the positive electrode  10 . The fuel gas and the oxidizer gas are introduced respectively through the fuel gas introduction holes  101   a  and the oxidizer gas introduction holes  101   b  of the separator  101  and flow through the channels  104  formed in the opposite surfaces of the separator  101 . 
     In the negative electrode  12 , the fuel gas is decomposed into electrons and cations (protons in the case where hydrogen is used as fuel) by the action of a catalytic material. 
     The cations generated in the negative electrode  12  move to the positive electrode  10  while passing through the electrolyte  11 , so that the cations come into contact with the oxidizer gas such as oxygen, or the like, flowing in the positive electrode  10 . 
     The positive electrode  10  is connected to the negative electrode  12  through a load (not shown). The electrons generated in the negative electrode  12  move to the positive electrode  10  through the load. 
     In the positive electrode  10 , the cations of the fuel which have passed through the electrode  11  are oxidized by an oxidizer. When, for example, hydrogen and oxygen are used as fuel gas and oxidizer gas respectively, an oxidation reaction of oxygen and hydrogen occurs in the positive electrode  10 . 
     On this occasion, electrons separated from the fuel in the negative electrode  12  move from the negative electrode  12  to the positive electrode  10  through the load to thereby contribute to the oxidation reaction in the positive electrode  10 . Electromotive force is generated by the movement of the electrons. 
     The fuel battery  100  generally has a structure in which a large number of cells are laminated to be connected in series so that a predetermined voltage is obtained. The number of cells to be laminated is generally from the order of tens to the order of hundreds or more. 
     Further, in the structure in which such a large number of cells are laminated, adjacent cells are separated from each other by the separator  101 . 
     Except for the edge portion of the laminated structure, the fuel gas such as hydrogen, or the like, flows through one surface of the separator  101  and the oxidizer gas such as oxygen, or the like, flows through the other surface of the separator  101 . 
     Because the fuel gas and the oxidizer gas must not be mixed with each other, it is a matter of course that the separator  101  requires a function of separating the two gases from each other. That is, the separator  101  requires gas-tightness so that no gas permeates through the separator  101  per se. 
     Further, because the separator  101  serves also as a member for electrically connecting the laminated cells to each other directly, the separator  101  requires a high electrically conductive property (low resistance) as the quality of the material thereof. 
     Further, the separator  101  requires resistance to water generated as a result of oxidation (water resistance), corrosion resistance to electrolyte contained in the electrolyte  11  and corrosion resistance to the oxidizer. 
     Further, because a strong compressing force is applied to the separator  101  in a condition that cells are laminated one another, the separator  101  requires great strength to withstand the compressing force. 
     As configuration for satisfying the aforementioned requirements, there are the following techniques. 
     One of the techniques is a technique of obtaining the separator  101  by cutting a block which is obtained by baking a vitreous carbon material also called glassy carbon (baked carbon). 
     Channels  104  are formed in the separator  101  so that the fuel gas and the oxidizer gas are made to flow through the channels  104 . Because glassy carbon is deformed greatly when baked, such a method that the separator  101  is produced by baking glassy carbon after molding the glassy carbon in a non-baked state cannot be applied. It is, therefore, necessary to obtain a required shape by cutting a glassy carbon block after the block is obtained by baking. 
     The baked glassy carbon is, however, so hard that high cost is required for cutting such baked glassy carbon. Furthermore, cutting loss occurs, so that the material is wasted. In view of this point, high cost is also required. 
     As another technique for obtaining the separator  101 , there is a method of obtaining the separator  101  from a mixed or kneaded matter. The mixed or kneaded matter is prepared by mixing or kneading a resin with a carbon type electrically conductive filler such as graphite powder or expansive graphite powder. 
     In this method, a predetermined shape can be obtained at a low cost by molding or hot-pressing. That is, a predetermined channel structure (a gas path structure which makes gas flow evenly) can be obtained relatively easily. 
     Although it is preferable, from the standpoint of electric power generating efficiency, that the electrically conductive property of the separator  101  is high, the amount of the electrically conductive filler to be mixed must be increased for obtaining the high electrically conductive property. As a result, there arises a problem that both strength and movability are lowered. Further, because the starting material is powder, there is another problem that dimensional stability in molding is bad. 
     Further, the separator  101  requires a function of enclosing the fuel gas and the oxidizer gas in predetermined channels  104  to prevent the gases from leaking out of the cell (sealing function). The sealing function is, however, spoiled when dimensional stability is lowered. 
     Further, because a large compressing force is applied to the cells in a state in which the cells are laminated, the separator  101  requires strength to withstand the compressing force. If the separator  101  is deformed, cracked or partially broken by the compressing force, the aforementioned gas-tightness or sealing property is spoiled undesirably. It is apparent also from this standpoint that increase in amount of the carbon type electrically conductive filler to be mixed is disadvantageous. That is, it is apparent that the strength of the separator  101  is lowered if the amount of the carbon type electrically conductive filler to be mixed is increased. 
     Furthermore, increase in amount of the electrically conductive filler to be mixed brings about a further problem that gas impermeability is lowered. 
     As described above, the techniques for obtaining the separator  101  for a fuel battery have problems as follows: 
     (1) In the method using glassy carbon, there is a problem in the cost of production. 
     (2) In the method using a resin material and an electrically conductive filler such as graphite powder, expansive graphite powder, or the like, there is a problem that it is difficult to make an electrically conductive property consistent with other requirements. 
     SUMMARY OF THE INVENTION 
     Therefore, the object of the present invention is to provide a technique of producing a separator for use in a fuel battery to satisfy simultaneously the following requirements: 
     the cost of production is low; 
     electrically conductive property is high; 
     gas-tightness is high; 
     dimensional stability is high (dimensional variation of products is small); and 
     mechanical strength is high. 
     In the present invention, attention is paid to the fact that a portion requiring great gas-tightness, great dimensional stability and great mechanical strength and a portion requiring a high electrically conductive property are distinguished from each other in a separator for a fuel battery obtained from a kneaded matter made of an electrically conductive filler and a resin material. Accordingly, the present invention is basically characterized in that optimum materials are used in the two portions respectively and a resin binder is contained in a collector portion. 
     In order to solve the above problems, there is provided a separator for a fuel battery having an electrically conductive property and being constituted by a collector portion provided with channels formed for making reactive gas flow through the channels, and a manifold portion having a composition different from that of the collector portion and provided with reactive gas introduction holes connected to the channels, the manifold portion being integrated with the collector portion so that a circumferential edge portion of the collector portion is surrounded by the manifold portion, wherein the collector portion contains a resin binder. 
     In order to solve the similar problems, there is provided a first method of producing a separator for a fuel battery comprising the steps of: forming the collector portion by using at least a resin binder and an electrically conductive filler as raw materials; and integrating the manifold portion with the collector portion by injection-molding a manifold portion-forming material of a composition different from that of the collector portion in the condition that the collector portion is disposed in a mold. 
     Further there is provided a second method of producing a separator for a fuel battery comprising the steps of: forming the collector portion by using at least a resin binder and an electrically conductive filler as raw materials; forming the manifold portion from a material different from that of the collector portion so that the manifold portion is divided into two in a direction of the plane of the manifold portion; and integrating the manifold portion with the collector portion in the condition that the collector portion is clamped by the manifold portion. 
     Further, there is provided a third method of producing a separator for a fuel battery comprising the steps of: forming the collector portion at least by using a resin binder and an electrically conductive filler as raw materials; forming a half of the manifold portion on one surface of the collector portion by injection-molding a manifold-portion-forming material of a composition different from that of the collector portion in the condition that the collector portion is disposed in a mold; and forming the other half of the manifold portion on the other surface of the collector portion by injection-molding the manifold-portion-forming material in the condition that the collector portion integrated with the one half of the manifold portion formed on the one surface of the collector portion is disposed in a mold. 
     The separator for use in a fuel battery according to the present invention is divided into a collector portion and a manifold portion. The collector portion is formed from a resin material which is mixed with a large amount of an electrically conductive filler so that the resin material has a high electrically conductive property at the sacrifice of gas-tightness, dimensional stability and mechanical strength. 
     On the other hand, the manifold portion is formed from a resin material which is mixed with a small amount of the electrically conductive filler or preferably contains no electrically conductive filler so that the resin material has gas-tightness, dimensional stability and mechanical strength preferentially. Further, because the manifold portion can be made to have high resistance (substantially, electrically insulating matter), there can be achieved a structure in which no current flows through the manifold portion so that there is no electric power loss caused by Joule heat. Further, generated electric power can be prevented from escaping from the manifold portion through a support portion. Further, containing of the resin material also in the collector portion satisfies the requirements of sealing function, dimensional stability, strength and moldability in the collector portion. 
     In this manner, a separator for a fuel battery with low electric power loss, high gas-tightness, high dimensional stability and high mechanical strength can be obtained. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing the external appearance of a separator according to the present invention; 
     FIGS. 2A and 2B are views showing an example of process for producing the separator according to the present invention; 
     FIG. 3 is a view showing another example of process for producing the separator according to the present invention; 
     FIGS. 4A,  4 B, and  4 C are views showing a further example of process for producing the separator according to the present invention; and 
     FIG. 5 is an exploded configuration view showing the outline of a fuel battery. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention will be described below in detail. 
     In the structure of the separator  101  shown as an example in FIG. 5, a center portion  102  in which channels  104  are formed requires a function for collecting generated electric power, that is, requires a high electrically conductive property. In the present invention, this portion  102  is called collector portion. 
     On the other hand, a peripheral portion (edge portion)  103  of the separator  101  requires a sealing property to prevent gases from leaking out of the cells. Accordingly, the portion  103  requires high mechanical strength and high dimensional stability. Furthermore, the portion  103  requires physical properties of gas impermeability. In the present invention, this portion is called manifold portion. 
     In the present invention, attention is paid to this standpoint, so that the collector portion  102  in the center portion of the separator  101  is formed to have an electrically conductive property preferentially by mixing an electrically conductive filler whereas the manifold portion  103  in the peripheral portion of the separator  101  is formed to have both strength and dimensional stability preferentially by mixing no electrically conductive filler. Further, a resin binder is contained in the collector portion so that both strength and dimensional stability required for the collector portion are ensured. 
     In this manner, the separator  101  which satisfies the aforementioned requirements simultaneously can be obtained. 
     The manifold portion  103  is a flame-like portion which exists so as to surround the circumferential edge portion of the collector portion  102  in which the channels  104  are formed. The manifold portion  103  has a sealing function to prevent the fuel gas and the oxidizer gas from leaking out. Further, the manifold portion  103  is provided with fuel gas introduction holes  101   a , oxidizer gas introduction holes  101   b  and cooling water introduction holes  101   c.    
     Further, the manifold portion  103  is also a portion on which a large compressing force acts. Further, the manifold portion  103  requires a sealing property. Accordingly, the manifold portion  103  requires high mechanical strength and high dimensional stability. 
     Accordingly, the manifold portion  103  may be made to be a portion which sacrifices electric performance in pursuit of other requirements. Therefore, the manifold portion  103  as a whole is preferably formed from a resin material. Alternatively, an electrically nonconductive filler such as glass fiber, or the like, may be mixed with the resin material so that improvement of mechanical strength can be attained. If there is no problem in mechanical strength, etc., a small amount of an electrically conductive filler can be mixed with the resin material. By mixing a small amount of the electrically conductive filler, the adhesion of the manifold portion  103  to the collector portion  102  containing the electrically conductive filler can be improved. It is, however, necessary to take care that the electric conductivity of the manifold portion  103  does not become too high. 
     As the resin material, a phenol resin, an epoxy resin, a nylon resin, a liquid-crystal polyester resin, or the like, can be used singly or in mixture. Compositions for the manifold portion  103  are exemplified in the following Table. Among these compositions, it may be said that it is preferable to use the liquid-crystal polyester resin singly or to use a mixture of 80% by weight or more of the liquid-crystal polyester resin with glass fiber. 
     
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Composition for the Manifold Portion (unit: part by weight) 
               
             
          
           
               
                   
                 Liquid-Crystal 
                   
                   
                   
                   
                   
                   
                 Dimensional 
                   
                   
               
               
                   
                 Polyester Resin 
                 Phenol Resin 
                 Epoxy Resin 
                 Nylon Resin 
                 Glass Fiber 
                 Strength 
                 Sealing Function 
                 Stability 
                 Moldability 
                 Evaluation 
               
               
                   
                   
               
             
          
           
               
                 1 
                 100  
                 — 
                 — 
                 — 
                 — 
                 High 
                 High 
                 High 
                 High 
                 ∘ 
               
               
                 2 
                 — 
                 100  
                 — 
                 — 
                 — 
                 High 
                 High 
                 Low 
                 Medium 
               
               
                 3 
                 — 
                 — 
                 100  
                 — 
                 — 
                 High 
                 High 
                 Low 
                 Medium 
               
               
                 4 
                 — 
                 — 
                 — 
                 100  
                 — 
                 High 
                 High 
                 Low 
                 Medium 
               
               
                 5 
                 90 
                 — 
                 — 
                 — 
                 10 
                 High 
                 High 
                 High 
                 High 
                 ∘ 
               
               
                 6 
                 — 
                 90 
                 — 
                 — 
                 10 
                 High 
                 High 
                 Medium 
                 Low 
               
               
                 7 
                 — 
                 — 
                 90 
                 — 
                 10 
                 High 
                 High 
                 Medium 
                 Low 
               
               
                 8 
                 — 
                 — 
                 — 
                 90 
                 10 
                 High 
                 High 
                 Medium 
                 Low 
               
               
                 9 
                 80 
                 — 
                 — 
                 — 
                 20 
                 High 
                 High 
                 High 
                 Medium 
                 ∘ 
               
               
                 10 
                 — 
                 80 
                 — 
                 — 
                 20 
                 High 
                 High 
                 Medium 
                 Low 
               
               
                 11 
                 — 
                 — 
                 80 
                 — 
                 20 
                 High 
                 High 
                 Medium 
                 Low 
               
               
                 12 
                 — 
                 — 
                 — 
                 80 
                 20 
                 High 
                 High 
                 Medium 
                 Low 
               
               
                   
               
             
          
         
       
     
     On the other hand, the collector portion  102  has an electrically conductive property and is provided with channels  104 . The channels  104  are formed in both surfaces of the collector portion  102  so that the fuel gas and the oxidizer gas are made to flow through the channels  104 . To integrate the collector portion  102  with the manifold portion  103 , an edge portion  102   a  is further formed so as to surround the channels  104  (see FIG.  3 ). 
     The collector portion  102  is obtained by binding an electrically conductive filler with a resin binder. As the electrically conductive filler, powder such as carbon powder, graphite powder, expansive graphite powder, or the like, can be used singly or in mixture. Of these powders, expansive graphite is particularly preferred because low electric resistance is obtained. Expansive graphite is used singly or as a main component. On the other hand, as the resin to serve as a binder, a phenol resin, an epoxy resin, a polyimide resin, a liquid-crystal polyester resin, or the like, can be used singly or in mixture. 
     Compositions for the collector portion  102  are exemplified in the following Table. It may be said that 60% by weight or more of expansive graphite in single use as the electrically conductive filler, or 70% by weight or more of expansive graphite in use as a main component is preferred, and that an epoxy resin or a phenol resin is preferably used as the resin. Incidentally, apparent from the following Table, the mixing of the resin binder in the collector portion makes it possible to simultaneously satisfy not only an electrically conductive property but also other requirements though the collector portion pursues electric performance first. 
     
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Composition for the Collector portion (unit: part by weight) 
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                   
                 Electrically 
                   
                   
                   
                   
                   
               
               
                   
                 Expansive 
                 Carbon 
                 Epoxy 
                 Phenol 
                 Liquid-Crystal 
                 Polyimide 
                 Conductive 
                 Sealing 
                 Dimensional 
               
               
                   
                 Graphite 
                 Powder 
                 Resin 
                 Resin 
                 Polyester Resin 
                 Resin 
                 property 
                 Function 
                 Stability 
                 Strength 
                 Moldability 
                 Evaluation 
               
               
                   
                   
               
             
          
           
               
                 1 
                 100  
                 — 
                 — 
                 — 
                 — 
                 — 
                 High 
                 Low 
                 Low 
                 Low 
                 Low 
                   
               
               
                 2 
                 90 
                 — 
                 10 
                 — 
                 — 
                 — 
                 High 
                 Medium 
                 Medium 
                 Medium 
                 Medium 
                 ∘ 
               
               
                 3 
                 90 
                 — 
                 — 
                 10 
                 — 
                 — 
                 High 
                 Medium 
                 Medium 
                 Medium 
                 Medium 
                 ∘ 
               
               
                 4 
                 90 
                 — 
                 — 
                 — 
                 10 
                 — 
                 High 
                 Medium 
                 Medium 
                 Medium 
                 Low 
               
               
                 5 
                 90 
                 — 
                 — 
                 — 
                 — 
                 10 
                 High 
                 Medium 
                 Medium 
                 Medium 
                 Low 
               
               
                 6 
                 60 
                 — 
                 40 
                 — 
                 — 
                 — 
                 Medium 
                 High 
                 High 
                 High 
                 High 
                 ∘ 
               
               
                 7 
                 60 
                 — 
                 — 
                 40 
                 — 
                 — 
                 Medium 
                 High 
                 High 
                 High 
                 High 
                 ∘ 
               
               
                 8 
                 60 
                 — 
                 — 
                 — 
                 40 
                 — 
                 Medium 
                 High 
                 High 
                 High 
                 Low 
               
               
                 9 
                 60 
                 — 
                 — 
                 — 
                 — 
                 40 
                 Medium 
                 High 
                 High 
                 High 
                 Low 
               
               
                 10 
                 80 
                 10 
                 10 
                 — 
                 — 
                 — 
                 High 
                 Medium 
                 Medium 
                 Medium 
                 Medium 
                 ∘ 
               
               
                 11 
                 80 
                 10 
                 — 
                 10 
                 — 
                 — 
                 High 
                 Medium 
                 Medium 
                 Medium 
                 Medium 
                 ∘ 
               
               
                 12 
                 80 
                 10 
                 — 
                 — 
                 10 
                 — 
                 High 
                 Medium 
                 Medium 
                 High 
                 Low 
               
               
                 13 
                 80 
                 10 
                 — 
                 — 
                 — 
                 10 
                 High 
                 Medium 
                 Medium 
                 High 
                 Low 
               
               
                 14 
                 20 
                 40 
                 40 
                 — 
                 — 
                 — 
                 Medium 
                 High 
                 High 
                 High 
                 Medium 
               
               
                 15 
                 20 
                 40 
                 — 
                 40 
                 — 
                 — 
                 Medium 
                 High 
                 High 
                 High 
                 Medium 
               
               
                 16 
                 20 
                 40 
                 — 
                 — 
                 40 
                 — 
                 Medium 
                 High 
                 High 
                 High 
                 Low 
               
               
                 17 
                 20 
                 40 
                 — 
                 — 
                 — 
                 40 
                 Medium 
                 High 
                 High 
                 High 
                 Low 
               
               
                   
               
             
          
         
       
     
     The collector portion  102  is integrated with the manifold portion  103  to thereby accomplish the separator  101  for a fuel battery according to the present invention. As for the method of integration, press-molding and another method shown in embodiments which will be described later are preferable. As shown in FIG. 1, the thus obtained separator  101  is configured so that the collector portion  102  is disposed in the center portion and the periphery of the collector portion  102  is surrounded by the manifold portion  103 . The separator  101  exhibits the same external appearance as that of the background-art separator  101  shown in FIG.  5 . 
     In the above description, the constituent resin material for the collector portion  102  may be made different in kind from that for the manifold portion  103 . In this case, it is important to select a combination of materials so that the collector portion  102  is fitted to the manifold portion  103  well so that integration of the two portions is not spoiled. 
     The present invention will be described below more in detail while the process of production is taken as an example. 
     First Embodiment 
     A method of producing a separator  101  by integrally molding a collector portion  102  and a manifold portion  103  will be described below with reference to FIGS. 2A and 2B. 
     First, as shown in FIG. 2A, a collector-portion-forming material (for example, a mixture of 70 parts by weight of expansive graphite to 30 parts by weight of epoxy resin) is molded to thereby produce a collector portion  102  which has channels  104  and edge portions  102   a  in both surfaces. Press-molding or injection-molding can be used as the molding method. Then, as shown in FIG. 2B, in the condition that the collector portion  102  is put in a mold, a manifold-portion-forming material (for example, a mixture of 80 parts by weight of liquid-crystal polyester resin to 20 parts by weight of glass fiber) is injection-molded to thereby integrally mold a separator  101 . 
     In this manner, there is achieved a structure in which the manifold portion  103  has an electrically insulating property, high mechanical strength and high dimensional stability whereas the collector portion  102  has a high electrically conductive property because of the mixing of a filler. 
     Second Embodiment 
     As shown in FIG. 3, the aforementioned collector-portion-forming material is molded to thereby produce a collector portion  102  which has channels  104  and edge portions  102   a  in both surfaces. Further, the manifold-portion-forming material is molded to thereby produce a pair of members  301  and  302  constituting a manifold portion  103 . The members  301  and  302  have a structure in which the man fold portion  103  is divided into two in a direction of the plane of the manifold portion  103 . Press-molding or injection-molding can be used as the method for molding each of the members  301  and  302 . Further, the thickness of each of the members  301  and  302  is made equal to the height of each of partition walls  104   a  forming the channels  104  of the collector portion  102 . 
     Further, the collector portion  102  is integrated with the members  301  and  302  so that the edge portions  102   a  of the collector portion  102  are clamped by the members  301  and  302 . In such a manner, the separator  101  according to the present invention is accomplished. Incidentally, an adhesive agent or pins can be used for the integration. 
     In the producing process shown in this embodiment, the edge portions  102   a  of the collector portion  102  low in mechanical strength can be prevented from being broken though there is a fear that the edge portions  102   a  may be broken in the case where press-molding or injection-molding is used. 
     Third Embodiment 
     As shown in FIG. 4A, the aforementioned collector-portion-forming material is molded to thereby produce a collector portion  102  having channels  104  and edge portions  102   a  in both surfaces. Then, in the condition that the collector portion  102  is put in a mold, a half (manifold member)  401  of a manifold portion  103  in a direction of the plane of the manifold portion  103  is formed on one surface of the edge portions  102   a  by an injection molding method, as shown in FIG.  4 B. Then, the remaining half (manifold member)  402  of the manifold portion  103  is formed on the other surface of the edge portions  102   a  by an injection molding method, as shown in FIG.  4 C. In this manner, the edge portions  102   a  of the collector portion  102  are held by the members  401  and  402  to thereby accomplish the separator  101  according to the present invention. 
     In the producing process shown in this embodiment, injection molding for producing the manifold portion  103  is divided into two steps. Accordingly, pressure applied to the edge portions  102   a  of the collector portion  102  is reduced when the manifold portion  103  is formed by injection-molding. Accordingly, the edge portions  102   a  can be prevented from being broken. 
     As described above, according to the present invention, it is possible to provide a separator for a fuel battery which can satisfy the following requirements simultaneously: 
     the cost of production is low; 
     electrically conductive property is high; 
     gas-tightness is high; 
     dimensional stability is high (dimensional variation of products is small); and 
     mechanical strength is high. 
     While only a certain embodiment of the invention has been specifically described herein, it will be apparent that numerous modifications may be made thereto without departing from the spirit and scope of the invention. 
     The present invention is based on Japanese Patent Application No. He. 11-5598 which is incorporated herein by reference.