Patent Publication Number: US-2017352845-A1

Title: Power battery top cover and power battery

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to Chinese Patent Application No. 201610399363.6, filed on Jun. 7, 2016, the content of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present application relates to the field of energy storage devices and, particularly, relates to a top cover of a power battery and a power battery. 
     BACKGROUND 
     In order to solve the overcharging problem of EV batteries, the generally adopted solution in the art is to cut off a main circuit of the battery before the battery exploded or catch fire, so as to prevent the battery from being charged continuously and guarantee safety of the battery. 
     At present, as for the square shell battery, a current interrupt device (Current Interrupt Device, CID) is generally adopted, i.e., a deformable plate and a conductive plate having integrated a CID are provided in the main circuit of the positive electrode. The conductive plate is coupled to the electrode tab of the bare cell and the deformable plate, and the deformable plate is welded with the positive terminal or the top cover plate. When the battery is overcharged, the deformable plate is inversely deformed due to excessive internal pressure, so as to disconnect the deformable plate from the conductive plate. 
     As there are increasing demands on the energy density of the power battery, demands on utilization rate of the internal space of the battery are increasing accordingly. 
     In view of the above, it is necessary to provide a structure which occupies as little internal space of the battery as possible. 
     SUMMARY 
     The present application provides a power batter top cover and a power battery, so as to solve the above problem. 
     A first aspect of the present application provides a top cover for a power battery, including a top cover plate, a first electrode unit and a second electrode unit, 
     wherein the first electrode unit includes a connecting plate, a deformable plate, an insulating piece and a current interrupt plate, 
     an assembling hole is formed in the top cover plate, the current interrupt plate is in direct contact with the top cover plate, 
     the connecting plate is insulated from the top cover plate through the insulating piece and is formed with an accommodating chamber, the accommodating chamber faces to the assembling hole, 
     the deformable plate is attached to the connecting plate and covers the accommodating chamber, and the deformable plate is electrically connected with the current interrupt plate, 
     the second electrode unit is electrically insulated from the top cover plate, and the deformable plate is configured to uncouple from the current interrupt plate when an internal pressure of the power battery goes beyond a reference pressure. 
     Preferably, the current interrupt plate seals the assembling hole; or 
     the current interrupt plate and the deformable plate seal the assembling hole. 
     Preferably, the deformable plate is in direct contact with a bottom edge of the accommodating chamber. 
     Preferably, a portion of the accommodating chamber away from the assembling hole is closed, and the deformable plate seals the accommodating chamber. 
     Preferably, a portion of the accommodating chamber away from the assembling hole is formed with an opening. 
     Preferably, a groove is formed at a bottom edge of the accommodating chamber, and an edge of the deformable plate is inserted into the groove. 
     Preferably, the deformable plate includes a connecting head, a deformable portion and an annular connecting portion, 
     the deformable portion is shaped into a circular sheet, the connecting head protrudes from a bottom surface of the deformable portion, the annular connecting portion surrounds an outer edge of the deformable portion, 
     the connecting head is connected to the current interrupt plate, and the annular connecting portion is inserted into the groove. 
     Preferably, the deformable plate and the connecting plate are integrated as a whole. 
     Preferably, the opening is covered by a protection member. 
     Preferably, the current interrupt plate and the top cover plate are integrated as a whole. 
     Preferably, the insulating piece is riveted with the top cover plate. 
     A second aspect of the present application provides a power battery including the power battery top cover. 
     The technical solutions provided by the present application can achieve the following beneficial effects: 
     In the power battery provided by the present application, the current interrupt plate is arranged on the top cover plate and the deformable plate is arranged on the connecting plate, so that the internal space of the battery occupied by the protection structure (e.g., the current interrupt plate and the deformable plate) is significantly reduced. 
     It should be understood that, the general description above and the detailed description below are merely exemplary, which shall not limit the present application. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an overall sectional side view of a power battery top cover according to an embodiment of the present application; 
         FIG. 2  is a partial enlarged view of part A shown in  FIG. 1  of a power battery top cover in which an accommodating chamber is a closed structure and a deformable plate is a separate structure, according to an embodiment of the present application; 
         FIG. 3  is a partial enlarged view of part A shown in  FIG. 1  of a power battery top cover in which an accommodating chamber is an open structure and a deformable plate is integrated with a connecting plate, according to an embodiment of the present application; 
         FIG. 4  is a structural schematic diagram of the structure shown in  FIG. 3  after the accommodating chamber is covered by a protection member; and 
         FIG. 5  is a partial enlarged view of part A shown in  FIG. 1  of a power battery top cover in which a deformable plate is connected with an insulating piece by riveting, according to an embodiment of the present application. 
     
    
    
     REFERENCE SIGNS 
       10 -top cover plate; 
       100 -assembling hole; 
       102 -riveting piece; 
       20 -first electrode unit; 
       200 -insulating piece 
       201 -current interrupt plate; 
       202 -deformable plate; 
       202   a -connecting head; 
       202   b -deformable portion; 
       202   c -annular connecting portion 
       203 -connecting plate; 
       204 -accommodating chamber; 
       205 -protection member; 
       206 -groove; 
       30 -second electrode unit. 
     The drawings herein are incorporated into the description and constitute a part of the description, which show the embodiments of the present application and are used to explain principles of the present application together with the description. 
     DESCRIPTION OF EMBODIMENTS 
     The present application is described in further details as follows with reference to embodiments and drawings. The expressions “front”, “rear”, “left”, “right”, “top” and “bottom” all refer to the placement states of the power battery top cover and the power battery in the drawings. 
     The present application provides a power battery, and the power battery includes a power battery top cover and a cell, etc. As shown in  FIGS. 1-4 , the power battery top cover includes a top cover plate  10 , a first electrode unit  20  and a second electrode unit  30 . The second electrode unit  30  is electrically insulated from the top cover plate  10 . The first electrode unit  20  includes an insulating piece  200 , a current interrupt plate  201 , a deformable plate  202  and a connecting plate  203 . In an embodiment, an assembling hole  100  is formed in the top cover plate  10 , the current interrupt plate  201  is arranged on the top cover plate  10  and is electrically connected with the top cover plate  10 , i.e., the current interrupt plate  201  is in direct contact with the top cover plate  10 . Preferably, the current interrupt plate  201  is arranged in the assembling hole  100 . 
     As the current interrupt plate  201  is arranged in the assembling hole  100  of the top cover plate  10 , the current interrupt plate  201  will not occupy the internal space of the power battery. The cell has two electrodes, and the two electrodes are connected with the top cover plate  10  and the second electrode unit  30 , respectively. 
     In order to guarantee normal working of the protection structure (e.g., the current interrupt plate  201  and the deformable plate  202 ), in the present embodiment, the connecting plate  203  is insulated from the top cover plate  10  through the insulating piece  200 . 
     In the present embodiment, the insulating piece  200  can be fixed with the riveting piece  102  by various manners, for example, adhering, clamping, riveting, etc. The adhering manner refers to that an adhesive is used to adhere a surface of the insulating piece  200  with a surface of the riveting piece  102 , however, such fixing manner may be not secure. The clamping manner needs to provide corresponding clamping pieces on the insulating piece  200  and the top cover plate  10 , the structure of which is complicated. As compared with the above two connecting manners, the riveting manner is simpler and more secure. As shown in  FIG. 5 , a riveting piece  102  can be provided on an upper surface of the top cover plate  10 , and a riveting hole (not numbered in the figures) is defined in a position of the insulating piece  200  corresponding to the riveting piece  102 ; during assembling, the riveting piece  102  passes through the riveting hole and is tightly riveted therein, so as to complete the fixing. 
     In some embodiments of the present embodiment, in order to improve the connecting strength between the connecting plate  203  and the insulating piece  200 , a clamping structure, e.g., clamping slot, clamping block, clamping hole, or buckle, etc., may be provided on the connecting plate  203  and the insulating piece  200 , so that the connecting plate  203  can be connected with the insulating piece  200  by a clamping manner with higher connecting strength. 
     Air leakage influences the normal breaking of the current interrupt plate  201 . In order to prevent from air leakage, in the present embodiment, it is better to seal the assembling hole  100  by the current interrupt plate  201 , so that the air pressure can be sufficiently applied on the current interrupt plate  201 . In some embodiments, in order to guarantee more secure connection between the current interrupt plate  201  and the deformable plate  202 , an opening is defined in the current interrupt plate  201 , a part of the deformable plate  202  is embedded in the opening, and in this case, the current interrupt plate  201  and the deformable plate  202  cooperatively seal the assembling hole  102 . 
     Further, both the connecting plate  203  and the insulating piece  200  may be sealedly connected with the top cover plate  10 , so that the air pressure will be applied on the current interrupt plate  201  and the deformable plate  202 . 
     The current interrupt plate  201  includes a weak area, e.g., a notch, the deformable plate  202  will pull the current interrupt plate when the deformable plate  202  deforms, and then the weak area will break as it cannot bear the pulling force. In order to provide enough space for deformation of the deformable plate  202 , the connecting plate  203  in the present embodiment is formed with an accommodating chamber  204 . The accommodating chamber  204  faces to the assembling hole  100 , that is to say, the deformable plate  202  is attached to the connecting plate  203  and covers the accommodating chamber  204 , and the deformable plate  202  is electrically connected with and fixed on the connecting plate  203  and is electrically connected with the current interrupt plate  201 . In the present embodiment, the deformable plate  202  is configured to uncouple from the current interrupt plate  201  when the internal pressure of the power battery goes beyond a reference pressure, i.e., the deformable plate  202  can deform and enter into the accommodating chamber  204  to be electrically disconnected with the current interrupt plate  201 , and the accommodating chamber  204  can provide enough space to accommodate the deformable plate  202  after deforming. 
     Under such configuration, the protection structure constituted by the current interrupt plate  201  and the deformable plate  202  is basically located outside the power battery and does not occupy the internal space of the power battery, so that the internal space of the power battery occupied by the protection structure is significantly reduced and the energy density of the battery is effectively improved. 
     As shown in  FIGS. 2-4 , in order to facilitate connection between the deformable plate  202  and the current interrupt plate  201 , it is preferred that the deformable plate  202  in the present embodiment is in direct contact with a bottom edge of the accommodating chamber  204 , so that the deformable plate  202  is closest to the current interrupt plate  201  and, at the same time, more space above the deformable plate  202  is provided for deformation of the deformable plate  202 . Further, it is preferred that the current interrupt plate  201  is arranged on a top end of the assembling hole  100  to be as close to the deformable plate  202  as possible, so that more space can be provided in the power battery. 
     In the present embodiment, the accommodating chamber  204  can be structured in various forms, for example, as shown in  FIG. 2 , a portion of the accommodating chamber  204  away from the assembling hole  100  is configured into a closed structure, so that the deformable plate  202  and the connecting plate  203  cooperatively define a closed space, i.e., the deformable plate  202  seals the accommodating chamber  204 . The closed space can be vacuumed, so as to reduce resistance when the deformable plate  202  deforms. As shown in  FIG. 3 , the portion of the accommodating chamber  204  away from the assembling hole  100  may is formed with an opening, so that the deformable plate  202  can directly communicate with the external environment. Since the opening exposes the deformable plate  202  in the external environment, articles from the external environment may directly contact the deformable plate  202 . In order to avoid such situation, a protection member  205  may be provided to cover the opening (See  FIG. 4 ). The protection member  205  may be a soft film, for example, PP film with good flexibility, or metal sheet. 
     In the present application, in order to facilitate manufacturing and assembling, the deformable plate  202  can be sealedly connected with the accommodating chamber  204  through various manners, two manners of which are illustrated in detail as follows. 
     As shown in  FIG. 2 , as a first manner, a groove  206  is formed at an edge of the accommodating chamber  204 , and an edge of the deformable plate  202  is inserted into the groove  206 . The deformable plate  202  may be configured into a structure including a connecting head  202   a , a deformable portion  202   b  and an annular connecting portion  202   c . The deformable portion  202   b  is shaped into a circular sheet, the connecting head  202   a  protrudes from a bottom surface of the deformable portion  202   b , and the annular connecting portion  202   c  surrounds an outer edge of the deformable portion  202   b . During assembling, the connecting head  202   a  is connected to the current interrupt plate  201 , and the annular connecting portion  202   c  is inserted into the groove  206 . Such manner can be adapted to various structural forms of the deformable plate accommodating chamber  204 . 
     As shown in  FIG. 3  and FIG. 4 , as a second manner, the deformable plate  202  and the connecting plate  203  are integrally molded by mold pressing, mechanical processing, etc. Due to limitation on processing process and structure, such manner is limited to a situation in which the portion of the accommodating chamber  204  away from the assembling hole  100  defines an opening. 
     The present application further provides a power battery, and the power battery adopts the power battery top cover of the present application, which can improve the energy density of the power battery. 
     The above are merely preferred embodiments of the present application, which are not used to limit the present application, and those skilled in the art may make various changes and modifications to the present application. All modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall fall into the protection scope of the present application.