Abstract:
A flexible current collecting fiber bunch comprises a plurality of current collecting fiber conductors and at least one electrical wire. There is an interval between each two adjacent current collecting fiber conductors. The electrical wire used to cascades the current collecting fiber conductors. The flexible current collecting fiber bunch may replace the graphite or metal bipolar commonly plate used in the fuel cell at lowers the pressure needed for a good contact and adds flexibility in the stack design.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to a current collector and fuel cell structure, more particularly to a flexible current collecting fiber bunch and fuel cell structure using the same. 
       BACKGROUND OF THE INVENTION 
       [0002]    Current collecting method of fuel cell that graphite or metal bipolar commonly plate contacting with electrode is applied to collect current generated by fuel cell has been known for years. However, graphite or metal bipolar commonly plate made of rigid material is too hard to be bent unable to be applied for flexible fuel cell. Besides, it is known that a force member is required to force on the graphite or metal bipolar commonly plate to increase contact area in order to reduce contact resistance between graphite or metal bipolar commonly plate and electrode, but assemblies used by fuel cell must be robust to be capable of bearing big pressure forced by force member, which cannot reach a target of flexibility, portability and light weight. 
       SUMMARY 
       [0003]    A primary object of the present invention is to provide a flexible current collecting fiber bunch and fuel cell structure using the same. The flexible current collecting fiber bunch comprises a plurality of current collecting fiber conductors and at least one electrical wire, wherein there is an interval between two current collecting fiber conductors, the electrical wire cascades the current collecting fiber conductors. The fuel cell structure comprises a membrane electrode assembly (MEA), at least one first flexible current collecting fiber bunch, at least one at least one elastic member and at least one second flexible current collecting fiber bunch. The MEA has an anode, a cathode and an electrolyte membrane disposed between the anode and the cathode. The first flexible current collecting fiber bunch which contacts the anode of the MEA has a plurality of first current collecting fiber conductors contacting the anode and at least one first electrical wire cascading the first current collecting fiber conductors. The elastic member presses on the first flexible current collecting fiber bunch or the second flexible current collecting fiber bunch. The second flexible current collecting fiber bunch which contacts the cathode of the MEA has a plurality of second current collecting fiber conductors contacting the cathode and at least one second electrical wire cascading the second current collecting fiber conductors. The flexible current collecting fiber bunch according to the present invention may replace the graphite or metal bipolar commonly plate used in the fuel cell at lowers the pressure need for a good contact and adds flexibility in the stack design. Moreover, the present invention, applying two elastic members to press the first flexible current collecting fiber bunch and the second flexible current collecting fiber bunch respectively so as to make the first flexible current collecting fiber bunch and the second flexible current collecting fiber bunch closely contact the anode and the cathode respectively within flexural process of fuel cell structure, is capable of reducing contact resistance between the first flexible current collecting fiber bunch, the second flexible current collecting fiber bunch and the electrodes and enhancing current collecting efficiency. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  is a structural view illustrating a fuel cell using flexible current collecting fiber bunch in accordance with the first preferred embodiment of the present invention. 
           [0005]      FIG. 2  is a structural view illustrating the first flexible current collecting fiber bunch in accordance with the present invention. 
           [0006]      FIG. 3  is a structural view illustrating the second flexible current collecting fiber bunch in accordance with the present invention. 
           [0007]      FIG. 4  is a view illustrating flexible state within the fuel cell in accordance with an embodiment of the present invention. 
           [0008]      FIG. 5  is a structural view illustrating another fuel cell using flexible current collecting fiber bunch in accordance with the second preferred embodiment of the present invention. 
           [0009]      FIG. 6  is a structural view illustrating the other fuel cell using flexible current collecting fiber bunch in accordance with the third preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]    With reference to  FIG. 1 , a fuel cell structure using flexible current collecting fiber bunch in accordance with the first preferred embodiment of the present invention is composed of a membrane electrode assembly (MEA)  10 , at least one first flexible current collecting fiber bunch  20 , at least one elastic member  30 , at least one second flexible current collecting fiber bunch  40 , at least one elastic member  50 , a first ending cover  60  and a second ending cover  70 . The MEA  10  has an anode  11 , a cathode  12  and an electrolyte membrane  13  disposed between the anode  11  and the cathode  12 . With reference to  FIGS. 1 and 2 , the first flexible current collecting fiber bunch  20  which contacts the anode  11  of the MEA  10  has a plurality of first current collecting fiber conductors  21  contacting the anode  11  and at least one first electrical wire  22  cascading the first current collecting fiber conductors  21 . Within this embodiment, each of the first current collecting fiber conductors  21  is formed by thermopressing carbon fibers to have a first flexible portion  211  and a first rigid portion  212  through controlling resin content within manufacturing process, otherwise within another embodiment, the first flexible portion  211  and the first rigid portion  212  may be manufactured with different materials and preferably formed by thermopressing different carbon fibers. Besides within this embodiment, there is a first interval S 1  between each two adjacent first current collecting fiber conductors  21  and preferably all of the first intervals S 1  are equal. The first electrical wire  22  is formed by metal having a plurality of first conductive segments  221  and a plurality of first connecting segments  222 , wherein each of the first conductive segments  221  is arranged alternately with each of the first connecting segments  222  and contacts with each of the first current collecting fiber conductors  21 . Within this embodiment, the first conductive segments  221  are placed between the carbon fibers prior to thermopressing process and then the first current collecting fiber conductors  21  encapsulate the first conductive segments  221  after thermoprocessing process, and preferably the first conductive segments  221  are inserted into the first rigid portions  212  of the first current collecting fiber conductors  21 . Otherwise within another embodiment, the first conductive segments  221  may be adhered to contact with the first current collecting fiber conductors  21 . With reference again to  FIGS. 1 and 2 , the first conductive segments  221  may be equal or unequal in length and preferably are equal to provide symmetrical flexibility. Each of the first connecting segments  222  is located between each two adjacent first current collecting fiber conductors  21  to connect with them and provides flexural area needed for the first flexible current collecting fiber bunch  20 . The first connecting segments  222  may be equal or unequal in length within this embodiment and preferably are equal to provide uniform flexibility. In addition, the first conductive segments  221  may be equal or unequal to the first connecting segments  222  in length within this embodiment, which depends on structural requirement in application. Otherwise within the other embodiment, the first flexible current collecting fiber bunch  20  is formed by coupling each of the first current collecting fiber conductors  21  with single first electrical wire  22  and then cascading all first electrical wires  22 . With reference to  FIGS. 1 and 4 , the elastic member  30  presses on the first current collecting fiber conductors  21  of the first flexible current collecting fiber bunch  20  to make the first current collecting fiber conductors  21  closely contact the anode  11  of the MEA  10  and prevent the first current collecting fiber conductors  21  from escaping the anode  11  within flexural process of fuel cell structure. Within this embodiment, the elastic member  30  is a spring wire with flexibility and two ends thereof are fixed at the first ending cover  60  by inserting or adhering method. With reference to  FIG. 4 , when the fuel cell structure is required to bend by user, the first flexible current collecting fiber bunch  20 , the elastic member  30  and the first ending cover  60  can be bent and the elastic member  30  still keeps pressing on the first flexible current collecting fiber bunch  20 , which makes the first current collecting fiber conductors  21  closely contact the anode  11  of the MEA  10 . 
         [0011]    With reference to  FIGS. 1 and 3 , the second flexible current collecting fiber bunch  40  which contacts the cathode  12  of the MEA  10  has a plurality of second current collecting fiber conductors  41  contacting the cathode  12  and at least one second electrical wire  42  cascading the second current collecting fiber conductors  41 . Within this embodiment, each of the second current collecting fiber conductors  41  is likewise formed by thermopressing carbon fibers to have a second flexible portion  411  and a second rigid portion  412  through controlling resin content within manufacturing process, otherwise within another embodiment, the second flexible portion  411  and the second rigid portion  412  may be manufactured with different material and preferably formed by thermopressing different carbon fibers. Besides within this embodiment, there is a second interval S 2  between each two adjacent second current collecting fiber conductors  41  and preferably all of the second intervals S 2  are equal. The second electrical wire  42  is formed by metal having a plurality of second conductive segments  421  and a plurality of second connecting segments  422 , wherein each of the second conductive segments  421  is arranged alternately with each of the second connecting segments  422  and contacts with each of the second current collecting fiber conductors  41 . Within this embodiment, the second conductive segments  421  are placed between the carbon fibers prior to thermopressing process and then the second current collecting fiber conductors  41  encapsulate the second conductive segments  421  after thermoprocessing process, and preferably the second conductive segments  421  are encapsulated by the second rigid portions  412  of the second current collecting fiber conductors  41 . Otherwise within another embodiment, the second conductive segments  421  may be adhered to contact with the second current collecting fiber conductors  41 . With reference again to  FIGS. 1 and 3 , the second conductive segments  421  may be equal or unequal in length and preferably are equal to provide symmetrical flexibility. Each of the second connecting segments  422  is located between each two adjacent second current collecting fiber conductors  41  to connect with them and provides flexural area needed for the second flexible current collecting fiber bunch  40 . The second connecting segments  422  may be equal or unequal in length within this embodiment and preferably are equal to provide uniform flexibility. In addition, the second conductive segments  421  may be equal or unequal to the second connecting segments  422  in length within this embodiment, which depends on structural requirement in application. Otherwise within the other embodiment, the second flexible current collecting fiber bunch  40  is formed by coupling each of the second current collecting fiber conductors  41  with single second electrical wire  42  and then cascading all second electrical wires  42 . With reference to  FIGS. 1 and 4 , the elastic member  50  presses on the second current collecting fiber conductors  41  of the second flexible current collecting fiber bunch  40  to make the second current collecting fiber conductors  41  closely contact the cathode  12  of the MEA  10  and prevent the second current collecting fiber conductors  41  from escaping the cathode  12  within flexural process of fuel cell structure. Within this embodiment, the elastic member  50  is a spring wire with flexibility and two ends thereof are fixed at the second ending cover  70  by inserting or adhering method. With reference to  FIG. 4 , when the fuel cell structure is required to bend by user, the second flexible current collecting fiber bunch  40 , the elastic member  50  and the second ending cover  70  can be bent and the elastic member  50  still keeps pressing on the second flexible current collecting fiber bunch  40 , which makes the second current collecting fiber conductors  41  closely contact the cathode  12  of the MEA  10 . 
         [0012]    With reference again to  FIGS. 1 and 4 , both the first and second ending covers  60 ,  70  have flexibility, the first ending cover  60  is disposed at one lateral of the anode  11  of the MEA  10 , the elastic member  30  is located between the first ending cover  60  and the first flexible current collecting fiber bunch  20 , and preferably two ends of the elastic member  30  are fixed at the first ending cover  60  respectively. Further, the second ending cover  70  is disposed at one lateral of the cathode  12  of the MEA  10 , the elastic member  50  is located between the second ending cover  70  and the second flexible current collecting fiber bunch  40 , and preferably two ends of the elastic member  50  are fixed at the second ending cover  70  respectively. Accordingly, the present invention applies the first flexible current collecting fiber bunch  20  and the second flexible current collecting fiber bunch  40  to replace graphite or metal bipolar commonly plate used for collecting current by known fuel cells, which may enhance flexibility of fuel cell structure in efficiency. Moreover, the present invention also, applying the two elastic members  30 ,  50  to press the first current collecting fiber conductors  21  of the first flexible current collecting fiber bunch  20  and the second current collecting fiber conductors  41  of the second flexible current collecting fiber bunch  40  respectively so as to make the first current collecting fiber conductors  21  and the second current collecting fiber conductors  41  closely contact the anode  11  and the cathode  12  respectively within flexural process of fuel cell structure, is capable of reducing contact resistance between the first flexible current collecting fiber bunch  20 , the second flexible current collecting fiber bunch  40  and the electrodes and enhancing current collecting efficiency. 
         [0013]    With reference to  FIG. 5 , a fuel cell structure using flexible current collecting fiber bunch in accordance with the second preferred embodiment of the present invention is composed of a membrane electrode assembly (MEA)  10 , at least one first flexible current collecting fiber bunch  20 , at least one elastic member  30 , at least one second flexible current collecting fiber bunch  40 , at least one elastic member  50 , a first ending cover  60  and a second ending cover  70 . The composition of this embodiment is basically same as that of the first preferred embodiment except that the first flexible current collecting fiber bunch  20  and the second flexible current collecting fiber bunch  40  use a plurality of first electrical wires  22  and a plurality of second electrical wires  42  respectively within this embodiment to enhance current collecting efficiency. Besides within this embodiment, the first connecting segments  222  of the first electrical wires  22  and the second connecting segments  422  of the second electrical wires  42  are bundled so as to increase tensile strength of the first flexible current collecting fiber bunch  20  and the second flexible current collecting fiber bunch  40 . 
         [0014]    With reference to  FIG. 6 , a fuel cell structure using flexible current collecting fiber bunch in accordance with the third preferred embodiment of the present invention is composed of a membrane electrode assembly (MEA)  10 , at least one first flexible current collecting fiber bunch  20 , at least one elastic member  30 , at least one second flexible current collecting fiber bunch  40 , at least one elastic member  50  and a first ending cover  60 . The composition of this embodiment is basically same as that of the first preferred embodiment except that the second ending cover  70  can be omitted within this embodiment. 
         [0015]    While this invention has been particularly illustrated and described in detail with respect to the preferred embodiments thereof, it will be clearly understood by those skilled in the art that is not limited to the specific features shown and described and various modified and changed in form and details may be made without departing from the spirit and scope of this invention.