Abstract:
To compliment the drawback of the conventional large-size reserve battery cell inapplicable to a small electronic system, disclosed is a super-slim reserve battery cell sized merely several millimeters in its entirety including micro-size battery elements sized about several μm by using a micro-machining technology of processing mechanical structures in a super-slim size. The present invention realized electrolyte container and other battery elements by using materials such as silicon, nickel, copper, aluminum, etc. to form a membrane structure of relatively thinner thickness than the periphery in an electrolyte container contiguous with the battery cell that is broken only when activating the cell. Therefore, it is possible to activate the battery cell with less power while securing sufficient impact-resistant characteristics under normal circumstances.

Description:
TECHNICAL FIELD 
   The present invention relates to a battery, and in particular, to a reserve battery cell activated to generate electric energy only when a user takes intentional actions. 
   In general, a battery comprises anode/cathode active materials and electrolyte generating electric energy by chemically reacting therewith. Unlike a primary/secondary battery, in which electrolyte is in contact with anode/cathode active materials under normal circumstances, a reserve battery initiates a role as a battery by mechanically breaking a separate closed container containing the electrolyte so that the electrolyte reacts with the active materials. Electrolyte is completely separated from the active materials in such a reserve battery cell. Thus, a reserve battery cell does not pose a problem of current leakage, unlike an ordinary battery cell, and can be retained for a long period of time. Moreover, the active materials and electrolyte of the reserve battery cell is very fresh at an initial stage of its usage, thereby creating no phenomenon of voltage retardation. For this reason, reserve battery cells occupy a major portion of the battery market as an emergency power supply or an energy source requiring a long retention period. 
   BACKGROUND ART 
   In the conventional reserve battery cell, electrolyte is generally retained in a ampoule made of glass. However, the glass ampoule can be manufactured to have a size at least longer than a centimeter with a thickness greater than hundreds of μ. Further, the shape of the glass ampoule is limited to a cylindrical shape. Therefore, the conventional reserve battery cells can be manufactured at a large size only, and a relatively stronger power is required to mechanically destroy the ampoule. Hence, the conventional reserve battery cells have a drawback of being inapplicable to a small electronic system requiring activation of a super-slim battery with less power. 
   SUMMARY OF THE INVENTION 
   It is, therefore, an object of the invention to provide a super-slim reserve battery cell applicable to a small electronic system and can be activated with a slight power. 
   To achieve the above and other objects, there is provided a reserve battery cell, comprising: a battery cell including a first electrode and a second electrode spaced by a separating member (the separating member is composed of a material absorbing electrolyte when the battery cell is activated); an electrolyte housing mounted on the battery cell for containing the electrolyte; a supporting member provided on a lower plate of the battery cell so as to be in electrical contact with the first electrode; a first sealing member composed of an insulating body for sealing side surfaces of the battery cell; a first membrane provided on a partial region of the electrolyte housing contiguous with the battery cell and has a relatively thinner thickness than the electrolyte housing; and a membrane-breaking member for breaking the first membrane to lead the electrolyte into the battery cell. 
   To compliment the drawback of the conventional large-size reserve battery cell inapplicable to a small electronic system, the present invention realized a super-slim reserve battery cell sized merely several millimeters in its entirety including micro-size battery elements sized about several μm by using a micro-machining technology of processing mechanical structures in a super-slim size. To be specific, the present invention realized electrolyte container and other battery elements by using materials such as silicon, nickel, copper, aluminum, etc. to form a membrane structure of relatively thinner thickness than the periphery in an electrolyte container contiguous with the battery cell that is broken only when activating the cell. Therefore, it is possible to activate the battery cell with less power while securing sufficient impact-resistant characteristics under normal circumstances. 
   The present invention is also directed to a reserve battery cell comprising an electrolyte container for containing electrolyte; a reaction container connected to the electrolyte container for generating an electromotive force with the electrolyte provided by the electrolyte container upon reception of an external impact, the reaction container including a wall separating the electrolyte container and the reaction container, the wall including a first membrane of a relatively thinner thickness easily breakable upon reception of the external impact, a surface of the reaction container facing the first membrane including a second flexible membrane of a relatively thinner thickness, a membrane for breaking the first membrane protrudes toward the first membrane from an inner wall of the second membrane, and the first and the second membranes have a thickness less than 20 μm, respectively. 
   The present invention is also directed to a reserve battery cell, comprising an electrolyte container for containing electrolyte; a reaction container including a first membrane formed on a region of a wall separating the electrolyte container from the reaction container and a second membrane formed on a surface of the reaction container facing the first membrane; and a member provided on an external surface of the reaction container for breaking the first and the second membranes upon reception of an external impact to activate the battery cell. 
   The present invention is also directed to a reserve battery cell, comprising an electrolyte container for containing electrolyte; a reaction container including a first membrane formed on a region of a wall separating the electrolyte container from the reaction container and a second, flexible membrane formed on a surface of the reaction container facing the first membrane and not extending past an outer surface of the reaction container; and a member protruding toward the first membrane from an inner wall of the second membrane, said member being positioned within the reaction container and capable of breaking the first membrane so as to lead the electrolyte into the reaction container for generating an electromotive force. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
       FIGS. 1A and 1B  are cross-sectional views of a super-slim reserve battery cell in accordance with an embodiment of the present invention; 
       FIGS. 2A and 2B  are cross-sectional views of a reserve battery cell in accordance with another embodiment of the present invention; and 
       FIGS. 3A and 3B  are cross-sectional views of a reserve battery cell in accordance with another embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Preferred embodiments of the present invention will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. 
     FIGS. 1A and 1B  are cross-sectional views of a super-slim reserve battery cell in accordance with an embodiment of the present invention. In particular,  FIG. 1A  illustrates an inert state of the reserve battery cell, while  FIG. 1B  illustrates an active state of the reserve battery cell. 
   Referring to  FIG. 1A , an electrolyte container  11  containing electrolyte  10  is composed of a conductive material including silicon, nickel, copper, aluminum, stainless steel, etc. An electrolyte injection inlet  12  is formed on an upper plate of the electrolyte container  11 . A membrane structure  11   a  is formed on a power portion of the electrolyte container  11 , i.e., at a center of a reaction container  29  generating electromotive force from the electrolyte  10 . 
   Meanwhile, such a membrane structure is formed to be thinner than the contiguous lower plate by carving a part of the lower plate of the electrolyte container  11  with a micro-machining technology. Therefore, the membrane structure  11   a  may be composed of the same material as the lower plate of the electrolyte container  11 . The electrolyte  10  is injected into the electrolyte container  11 , and the injection inlet  12  is firmly sealed with a sealant  13  to retain the electrolyte  10  for a long period of time. Materials chemically not reactive with the electrolyte  10 , such as epoxy resin, plastic resin, indium, etc., are used for the sealant  13 . An anode material  14  is mounted beneath the lower plate of the electrolyte container  11  except the portion occupied by the membrane structure  11   a  so as to be in electric contact with the lower plate. Cathode materials  15  are spaced by a separator  16 , which is composed of a nonconductor that can absorb the electrolyte  10  such as non-woven glass fiber, paper, etc. A lower plate  17 , which includes a membrane structure  17   a  of a slim thickness and is electrically connected to the cathode materials  15 , is formed at the center of the lowest portion of the battery cell. 
   Meanwhile, a vacant space exists between the membrane structures  11   a ,  17   a  of the upper and lower portions of the lower plate  17 . The lower plate  17  may be composed of any one material selected from silicon, nickel, copper, aluminum and stainless steel. The periphery of the battery cell is sealed with the sealant  18  such as epoxy resin so as to protect the cathode materials  15  and the separator  16  from external environment. The battery cell shown in  FIG. 1A  is in inert state because the electrolyte  10  is separated from the electrodes  14 ,  15 . 
   As shown in  FIG. 1B , however, the central portion of the battery cell may be penetrated by an acute needle  19 , depending on the user&#39;s will. Then, the needle  19  enters the battery cell by breaking the membrane structure  17   a  of the lower plate  17 . If the needle  19  continuously breaks the membrane structure  11   a  of the lower plate of the electrolyte container  11 , the electrolyte  10  is absorbed into the separator  16  to activate the battery cell. Since the penetration by the needle  19  is maintained while the battery cell is activated and in use, an external surface of the needle  19  should be composed of a nonconductive material. Moreover, in order to prevent leakage of the electrolyte out of the battery cell, an o-ring  20  may be attached to the needle  19 . Other devices than the a-ring  20  may be mounted on the needle  19  or a lower end of the battery cell to prevent leakage of the electrolyte. 
   According to an embodiment of the present invention, it is preferable to employ: SOCl 2  solution for the electrolyte  10 ; lithium film of 0.05 thickness for the anode material  14 ; carbon (acetylene black) film of 0.2 mm thickness for cathode materials  15 ; and non-woven glass fiber of 0.1 mm thickness composed of glass fiber for the separator  16 . It is also preferable to employ nickel of 0.1 mm thickness for the electrolyte container with its cubic size being 5.0 mm×5.0 mm×1.0 mm. The injection inlet  12  has a diameter preferably of 0.5 mm, and the membrane structure of the lower plate  17  of the electrolyte container  11  is designed to have a diameter preferably of 1.0 mm and a thickness preferably of 5.0 μm. The lower plate  17  generally composed of nickel has a thickness preferably of 0.1 mm. The membrane structure  17   a  of the lower plate  17  is designed to have a diameter preferably of 1.0 mm and a thickness preferably of 5.0 μm. The needle  19  for breaking the membrane structures  11   a ,  17   a  is preferably composed of any one element selected from silicon, ceramic, glass, nickel, copper and aluminum. The needle  19  is designed to have a diameter preferably smaller than that of the membrane structures  11   a ,  17   a . If a conductive material such as nickel, aluminum or copper is to be employed for the needle  19 , nonconductive material is coated on the needle  19  to prevent short circuit between the two electrodes. The electrolyte container  11  and the lower plate  17  of a microstructure such as the membrane structures  11   a ,  17   a  can be manufactured by using the micro-machining technology. 
     FIGS. 2A and 2B  are cross-sectional views of a reserve battery cell in accordance with another embodiment of the present invention. The same drawing reference numerals as those in  FIGS. 1A and 1B  were used in  FIGS. 2A and 2B  for the identical elements.  FIG. 2   a  illustrates an inert state of the reserve battery cell, while  FIG. 2B  illustrates an active state of the reserve battery cell. 
   Referring to  FIG. 2A , the comprehensive structure of the battery cell is similar to that in  FIG. 1A  except that: no membrane structure is formed on the lower plate  17 ; the upper plate of the electrolyte container  11  is formed to have a thickness less than 50 μm so as to be slim and flexible; and the needle  19  is mounted on the central portion of the upper plate of the electrolyte container  11 . Under an inert state of the battery cell, the needle  19  is slightly spaced from the membrane structure  11   a  of the lower plate of the electrolyte container  11 , and is designed to have a smaller diameter than that of the membrane structure  11   a.    
   As shown in  FIG. 2B , if the central portion of the upper portion of the electrolyte container  11  is pressed by a stick  21 , etc. according to the user&#39;s will, the membrane structure  11   a  of the lower plate of the electrolyte container  11  is broken to activate the battery cell. Since the upper plate of the electrolyte container  11  is flexible, the electrolyte container  11  is easily bent by even a slight power so that the needle  19  can break the membrane structure  11   a  of the lower plate of the electrolyte container  11 . Also, the battery cell of this structure can be activated by an acceleration without any additional mechanical force such as pressure with a stick. In other words, the upper plate of the electrolyte  11  is bent by a force generated by an acceleration and a weight of the needle  19 , and as a consequence, the needle  19  breaks the membrane structure  11   a  of the lower plate of the electrolyte container  11 , thereby activating the battery cell. 
     FIGS. 3A and 3B  are cross-sectional views of a reserve battery cell in accordance with another embodiment of the present invention. The same drawing reference numerals as those in  FIGS. 1A and 1B  were used in  FIGS. 3A and 3B  for the identical elements.  FIG. 3A  illustrates an inert state of the reserve battery cell, while  FIG. 3B  illustrates an active state of the reserve battery cell. 
   Referring to  FIG. 3A , the comprehensive structure of the battery cell is similar to that in  FIG. 1A  except that the needle  19  is mounted on the flexible membrane structure  17   a  of the lower plate  17 . If the central portion of the lower plate  17  is pressed by the stick  21 , as shown in  FIG. 3B , the needle  19  breaks the membrane structure  11   a  of the lower plate of the electrolyte container  11  to activate the battery cell. Also, the battery cell of this structure can be activated by an acceleration without any additional mechanical force such as pressure with a stick. 
   The reserve battery cell according to other two embodiments of the present invention has an advantage of being dispensable with an additional device for preventing leakage of the electrolyte because the battery is activated without breaking an external surface thereof and no electrolyte is leaked outside as a consequence. 
   Further, the super-slim size of the reserve batter cell according to the present invention is suitable for an energy source of a small electronic system such as a sensor. The super-slim reserve battery cell according to the present invention also has a high impact resistance, and is easily activated by even a slight power. 
   While the invention has been shown and described with reference to certain preferred embodiments thereof, 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. 
   For instance, the above embodiments exemplified a case of setting the thickness of the membrane structure to be 5.0 μm. However, the principle of the present invention is applicable to the case when the thickness of the membrane structure is less than 20 μm. The technical principle of the present invention is also applicable to the case of switching the positions of the anode material and the cathode materials when necessary.