Patent Publication Number: US-2023141846-A1

Title: Battery cell structure of button battery and munufactuturn merhod thereof, and button battery

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of International Application No. PCT/CN2021/138942, filed on Dec. 16, 2021, which claims priority to Chinese Patent Application No. 202011496907.3, entitled with “BATTERY CELL STRUCTURE OF BUTTON BATTERY AND MANUFACTURING METHOD THEREOF, AND BUTTON BATTERY”, filed with China National Intellectual Property Administration on Dec. 17, 2020. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the technical field of batteries, and, in particular, to a battery cell structure of a button battery and a manufacturing method thereof, and a button battery. 
     BACKGROUND 
     Button batteries have the advantages of stable discharge voltage, wide working temperature range, long storage life and so on, and are widely used in various electronic products. The demand for button batteries in wearable devices such as wireless headphones, sports watches, bracelets, turns and so on is increasing. 
     Button batteries need to improve the safety for long-term use in harsh environments, particularly in bumpy environments. However, limited by the development of industrial manufacturing level, and market demand, button batteries in the market are mainly primary batteries, while secondary button lithium-ion batteries are basically not sold in the market. Miniaturized electronic products have high requirements for the space size of battery products, and button batteries pose a huge challenge to manufacturing technology due to the reduction of battery size and the improvement of requirements for size consistency. Button batteries with steel housing structure can meet people&#39;s needs better. In harsh environments, particularly in bumpy environments or in the case of falling, the battery cell of the existing button battery is easy to generate a phenomenon that a positive electrode sheet and a negative electrode sheet move and shift, resulting in a short circuit caused by contacting with a metal housing, which affects the use safety. 
     Under this demand, we urgently need to provide a secondary hard-housing micro lithium-ion battery to meet the needs of the majority of users. By improving a battery cell structure of a button battery and a manufacturing method thereof, and a button battery, the phenomenon that a positive electrode sheet and a negative electrode sheet are easy to move and shift can be effectively solved, thereby avoiding a short circuit caused by contacting with a metal housing in a button battery. 
     SUMMARY 
     The present disclosure provides a battery cell structure of a button battery and a manufacturing method thereof, and a button battery, for at least solving the technical problem that a positive electrode sheet and a negative electrode sheet are easy to move and shift, thereby avoiding a short circuit caused by the contact of the positive electrode sheet and the negative electrode sheet with a housing in the button battery, and improving the use safety of button batteries. 
     In order to achieve the above purpose, the present disclosure provides a battery cell structure of a button battery, including a winding core which is formed by winding a laminated structure and is provided with a hollow inner hole, where the winding core is provided with a first tab and a second tab, the laminated structure includes at least one positive electrode sheet, at least one negative plate, and a separator which separates the at least one positive electrode sheet from the at least one negative electrode sheet, at least two ends of the winding core are provided with a separator bonding layer wrapping the winding core, and the separator bonding layer is configured to fix the positive electrode sheet and the negative electrode sheet. 
     In the present disclosure, the separator bonding layer is disposed such that the separator bonding layer wraps the two ends of the winding core, and thus the separator bonding layer covers and wraps the positive electrode sheet and the negative electrode sheet, and wraps the positive electrode sheet or the negative electrode sheet in a sealed region. This limits the positive electrode sheet or the negative electrode sheet to move and shift, so that it can be ensured that the positive electrode sheet and the negative electrode sheet do not come out of the winding core even under severe vibration conditions, for example, in the cases of running or falling, thereby avoiding a short circuit cause by the contact of the positive electrode sheet/or the negative electrode sheet with a battery housing, and improving the use safety of the battery cell structure of the button battery. 
     In a possible embodiment, the separator extends outwards from both ends of the winding core respectively and forms protruding ends, the protruding ends are inclined toward the direction of the inner hole of the winding core, and the adjacent protruding ends are bonded with each other to form the separator bonding layer. 
     In a possible embodiment, the width D of the protruding ends is greater than or equal to the sum of the thickness of the positive electrode sheet, the thickness of the negative electrode sheet, and the thickness of the separator. 
     In a possible embodiment, when the first tab is located at the outer ring of the winding core, the separator is disposed at the outer side of the positive electrode sheet/or the negative electrode sheet connected to the first tab; 
     the separator bonding layer includes a first separator bonding layer located at the inner side of the first tab and a second separator bonding layer located at the outer side of the first tab, and the bonding force of the first separator bonding layer is greater than that of the second separator bonding layer. 
     In a possible embodiment, when the first tab is located at the inner ring of the winding core, the separator is disposed at the inner side of the positive electrode sheet/or the negative electrode sheet connected to the first tab; 
     the separator bonding layer includes a second separator bonding layer located at the inner side of the first tab and a first separator bonding layer located at the outer side of the first tab, and the bonding force of the first separator bonding layer is greater than that of the second separator bonding layer. 
     In a possible embodiment, the area of the second separator bonding layer covering the first tab accounts for 5% to 30% of the area of the first tab. 
     In a possible embodiment, before the separator bonding layer is formed, the separator has a width A of 4 mm-10 mm, and after the separator bonding layer is formed, the separator has a width A2 of 3 mm-9 mm. 
     In a possible embodiment, the positive electrode sheet has a width B of 2 mm-8 mm, and the negative electrode sheet has a width C of 2.5 mm-8.5 mm. 
     The present disclosure further provides a button battery, including the above battery cell structure of the button battery, where the button battery further includes a housing in which a holding cavity for holding the battery cell structure of the button battery is provided, a bent portion of the first tab is located on at least one end face of the winding core, the bent portion of the first tab contacts the separator bonding layer, and the bent portion of the first tab is electrically connected to an end face of the housing. 
     The present disclosure further provides a method for manufacturing a battery cell structure of a button battery, the method is used to manufacture the above battery cell structure of the button battery, including: 
     providing a winding core, where the winding core includes a positive electrode sheet, a negative electrode sheet and a separator separating the positive electrode sheet from the negative electrode sheet; 
     providing a first tab and a second tab; 
     welding the first tab and the second tab; 
     providing a heating plate and heating the heating plate to a preset temperature, including providing an arc heating plate, and a first planar heating plate, and heating the arc heating plate, and the first planar heating plate to a preset temperature which is 122° C. to 128° C.; 
     scraping, by the heating plate, the separator at both ends of the winding core from outside to inside, so that the protruding ends of the separator form inclined protruding ends; 
     thermally pressing the inclined protruding ends by the heating plate to form the separator bonding layer which is sequentially bonded and contracted; 
     scrapingly pressing the first tab and the second tab to make them press against the end faces of the separator bonding layer; 
     scrapingly pressing the separator at the outermost ring/or innermost ring of the winding core to make the separator bonded to the separator bonding layer. 
     The present disclosure provides a method for manufacturing a battery cell structure of a button battery, which is used to manufacture the above battery cell structure of the button battery. The method has a simple manufacturing process. In the present disclosure, a separator bonding layer is formed at the both ends of a winding core by a separator using hot-pressing technology, and thus the positive electrode sheet and the negative electrode sheet are completely wrapped in a sealed region. This significantly improves the use safety of button batteries in use for a long time in severe environments, especially in bumpy environments. 
     For the method for manufacturing the battery cell structure of the button battery provided by the present disclosure, the positive electrode sheet and the negative electrode sheet are completely isolated from the housing of the button battery by forming the separator bonding layer which completely wraps the positive electrode sheet and the negative electrode sheet, so as to avoid a short circuit caused by the moving and shifting of the positive electrode sheet and the negative electrode sheet to contact with the housing of the button battery. The battery cell structure of the button battery and the manufacturing method thereof, and the button battery provided by the present disclosure are convenient to manufacture button batteries. Button batteries manufactured by using the battery cell structure of the button battery provided by the present disclosure can effectively improve the use safety of button batteries, can be normally used without being influenced in bumpy environments, and has a wide application range. 
     In addition to the technical problems solved by the embodiments of the present disclosure described above, the technical features constituting technical solutions, and the beneficial effects brought by the technical features of these technical solutions, other technical problems that can be solved by the battery cell structure of the button battery and the manufacturing method thereof, and the button battery provided by the present disclosure, other technical features contained in the technical solutions, and the beneficial effects brought by these technical features will be further described in detail in specific embodiments. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       In order to explain embodiments of the present disclosure or the technical solutions in the prior art more clearly, the following will make a brief introduction to the drawings needed in the embodiments or the prior art description. Apparently, the drawings in the following description are merely a part of embodiments of the present disclosure. For persons of ordinary skill in the art, it is also possible to obtain other drawings from these drawings without paying creative effort. 
         FIG.  1    is a schematic structural diagram in which an arc heating plate is used to extrude a winding core when a first tab and a second tab are both located in an inner ring of the winding core in a method for manufacturing a battery cell structure of a button battery according to an embodiment of the present disclosure. 
         FIG.  2    is a schematic structural diagram in which a first planar heating plate is used to extrude a winding core when a first tab and a second tab are both located in an inner ring of the winding core in a method for manufacturing a battery cell structure of a button battery according to an embodiment of the present disclosure. 
         FIG.  3    is a schematic structural diagram in which a first planar heating plate is used to extrude a winding core when a first tab and a second tab are both located in an outer ring of the winding core in a method for manufacturing a battery cell structure of a button battery according to an embodiment of the present disclosure. 
         FIG.  4    is a schematic structural diagram in which a second planar heating plate is used to extrude a winding core when a first tab and a second tab are both located in an outer ring of the winding core in a method for manufacturing a battery cell structure of a button battery according to an embodiment of the present disclosure. 
         FIG.  5    is a schematic structural diagram in which a second planar heating plate is used to extrude a winding core when a first tab and a second tab are both located in an inner ring of the winding core in a method for manufacturing a battery cell structure of a button battery according to an embodiment of the present disclosure. 
         FIG.  6    is a schematic structural diagram of a battery cell structure of a button battery before hot pressing according to an embodiment of the present disclosure. 
         FIG.  7    is a schematic structural diagram of a battery cell structure of a button battery according to an embodiment of the present disclosure. 
         FIG.  8    is a schematic partial structural diagram of a battery cell structure of a button battery before a separator is scraped according to an embodiment of the present disclosure. 
         FIG.  9    is a schematic partial structural diagram of a battery cell structure of a button battery after a separator is scraped according to an embodiment of the present disclosure. 
         FIG.  10    is a schematic partial structural diagram of a battery cell structure of a button battery after a separator bonding layer is formed according to an embodiment of the present disclosure. 
         FIG.  11    is a structural schematic diagram of a battery cell structure of a button battery when mounted with a housing according to an embodiment of the present disclosure. 
         FIG.  12    is a flowchart of a method for manufacturing a battery cell structure of a button battery according to an embodiment of the present disclosure. 
     
    
    
     DESCRIPTION OF REFERENCE NUMERALS 
       10 -winding core; 
       11 -positive electrode sheet; 
       12 -negative electrode sheet; 
       13 -separator; 
       131 -protruding end; 
       132 -separator bonding layer; 
       14 -inner hole; 
       20 -first tab; 
       21 -bent part; 
       30 -second tab; 
       40 -heating plate; 
       41 -arc heating plate; 
       42 -first planar heating plate; 
       43 -second planar heating plate; 
       50 -housing; 
       51 -holding cavity. 
     DESCRIPTION OF EMBODIMENTS 
     To make the objectives, technical solutions, and advantages of the present disclosure clearer, the technical solutions in embodiments of the present disclosure will be described clearly and comprehensively below with reference to the embodiments of the present disclosure. Apparently, the described embodiments are merely a part rather than all embodiments of the present disclosure. All other embodiments obtained by persons of ordinary skill in the art based on embodiments of the present disclosure without creative effort shall fall within the protection scope of the present disclosure. 
     In life, we will find that button batteries are widely used in many ultra-thin, small and exquisite electronic products, such as weighing machines, electronic watches, wireless headphones, and so on. Button batteries have the characteristics of small size and small battery discharge current, are the preferred power supply for the endurance of many electronic products, and also profit the development of electronic products towards miniaturization. 
     A battery cell structure is a core component of a button battery. The battery cell structure of the button battery is mainly prepared by two preparation processes. One is a lamination process in which a positive electrode sheet, a negative electrode sheet, and a separator are cut into shapes and sizes required for specific production, and then the positive electrode sheet, the separator, and the negative electrode sheet are laminated into a main body of a battery cell; the other is a winding process in which a separator is disposed between a positive electrode sheet and a negative electrode sheet, and then the positive electrode sheet, the negative electrode sheet and the separator are wound into a main body of a battery cell. 
     The lamination process needs to cut a positive electrode sheet, a negative electrode sheet and a separator into shapes and sizes required for specific production, which is more complicated and requires more production time. The winding process is simple in operation, which only needs to dispose a positive electrode sheet, a negative electrode sheet and a separator into a regular strip-shaped structure with a certain size, so that the winding process is simple and convenient, can be quickly completed, and is easy to realize industrial automation. Therefore, the battery cell structures of most button batteries adopt the winding process. 
     However, in harsh environments, particularly in bumpy environments or in the case of falling, the existing button batteries are easy to generate a phenomenon that a positive electrode sheet and a negative electrode sheet move and shift, resulting in a short circuit caused by contacting with a metal housing, which affects the use safety. 
     In view of the above background, a battery cell structure of a button battery and a manufacturing method thereof, and a button battery provided by the present disclosure improves a battery cell structure of a button battery and a manufacturing method thereof, and a button battery, so as to avoid a phenomenon that a positive electrode sheet and a negative electrode sheet move and shift in bumpy environments or in the case of falling, thereby avoiding a short circuit and improving the service life and the use safety. 
     As shown in  FIG.  7    and  FIG.  8   , a battery cell structure of a button battery includes a winding core  10  which is formed by winding a laminated structure and is provided with a hollow inner hole  14 . The laminated structure includes at least one positive electrode sheet  11 , at least one negative plate  12  and a separator  13  which separates the at least one positive electrode sheet  11  from the at least one negative electrode sheet  12 . At least two ends of the winding core  10  are provided with a separator bonding layer  132  wrapping the winding core, and the separator bonding layer  132  is used for fixing the positive electrode sheet  11  and the negative electrode sheet  12 . The separator bonding layer  132  enable the positive electrode sheet  11  and the negative electrode sheet  12  to be steadily wrapped in a sealed region, thereby avoiding a short circuit caused by the moving and shifting of the positive electrode sheet  11  and the negative electrode sheet  12  to contact with a battery housing  50  when the button battery is subject to severe vibration such as falling, and improving the use safety. 
     The inner hole  14  is located at the center of the winding core  10  and passes through both end faces of the winding core  10 . 
     As shown in  FIG.  6    and  FIG.  8   , the separator  13  extends outward from both ends of the winding core  10  and forms protruding ends  131 . As shown in  FIG.  9    and  FIG.  10   , the protruding ends  131  are inclined toward the direction of the inner hole  14  of the winding core  10 , and adjacent protruding ends  131  are bonded with each other to form the separator bonding layer  132 . 
     It is easy to understand that both sides of the separator  13  respectively extend outward from both ends of the winding core  10 . That is, the separator  13  extends, along the axial direction of the winding core  10 , from both ends of the winding core  10  to the direction away from the winding core  10 . 
     Specifically, in the laminated structure, the width of the separator  13  is greater than that of each positive electrode sheet  11 , and the width of the separator  13  is also greater than that of each negative electrode sheet  12 , so that after the laminated structure is wound along the length direction of the separator  13  to form the winding core  10 , the separator  13  is remained at both ends of the winding core  10 , and the remaining separator  13  beyond the winding core  10  is the protruding ends  131 . 
     As shown in  FIG.  6    and  FIG.  8   , the winding core  10  may be formed by sequentially stacking a positive electrode sheet  11 , a separator  13 , a negative electrode sheet  12 , and another separator  13  from top to bottom or from bottom to top to form a laminated structure, then subjecting the laminated structure to a winding process; the winding core  10  may also be formed by sequentially stacking a negative electrode sheet  12 , a separator  13 , a positive electrode sheet  11 , and another separator  13  from top to bottom or from bottom to top to form a laminated structure, then subjecting the laminated structure to a winding process. 
     Of course, the laminated structure may also be disposed by alternately stacking a plurality of negative electrode sheets  12  and a plurality of positive electrode sheets  11  in order, and disposing separators  13  at the upper and lower sides of each negative electrode sheet  12 /or each positive electrode sheet  11  for completely separating each negative electrode sheet  12  from each positive electrode sheet  11 . The laminated structure is formed into the winding core  10  by a winding process. Even after the winding core  10  is wound, it should be ensured that the negative electrode sheet  12  is not in contact with the positive electrode sheet  11  to avoid a short circuit. 
     The separator  13  is used to prevent the negative electrode sheet  12  from contacting with the positive electrode sheet  11  to cause a short circuit. The separator  13  needs to ensure that each negative electrode sheet  12  is completely separated from each positive electrode sheet  11  to prevent contact. The separator  13  is not limited to being disposed between each negative electrode plate  12  and each positive electrode plate  11 , and may also be sleeved on each negative electrode plate  12 , or on each positive electrode sheet  11 , so that each negative electrode sheet  12  is completely separated from each positive electrode sheet  11 . 
     The separators  13  are located outside and inside the at least one positive electrode sheet  11 /or outside and inside the at least one negative electrode sheet  12  so that each positive electrode sheet  11  is completely separated from each negative electrode sheet  12 . That is, the separators  13  are located outside and inside the at least one positive electrode sheet  11  so that each positive electrode sheet  11  is completely separated from each negative electrode sheet  12 . Alternatively, the separators  13  are located outside and inside the at least one negative electrode sheet  12  so that each positive electrode sheet  11  is completely separated from each negative electrode sheet  12 . 
     As shown in  FIG.  6   , the winding core  10  is spirally wound so as to have distinct spiral rings at both ends of the winding core  10 , and the protruding ends  131  of the separator  13  at each ring are inclined toward the direction of the inner hole  14  of the winding core  10  and bonded to the protruding ends  131  of the separator  13  at an adjacent inner ring. 
     As shown in  FIG.  10   , the protruding ends  131  of the separator  13  at each ring partially overlap with the protruding ends  131  of the separator  13  at the adjacent inner ring. Therefore, in order to ensure that the protruding ends  131  of the separator  13  at each ring partially overlap with the projecting ends  131  of the separator  13  at the adjacent inner ring, the width D of the protruding ends  131  needs to satisfy that D is greater than or equal to the sum of the thickness of the positive electrode sheet  11 , the thickness of the negative electrode sheet  12 , and the thickness of the separator  13 . 
     As shown in  FIG.  6    and  FIG.  7   , a first tab  20  and a second tab  30  are respectively disposed at both ends of the winding core  10 , one of the first tab  20  and the second tab  30  is a positive tab, the other of the first tab and the second tab  30  is a negative tab, the positive tab is connected to the positive electrode sheet  11 , and the negative tab is connected to the negative electrode sheet  12 . 
     As shown in  FIG.  6    and  FIG.  7   , when the first tab  20  is located at an outer ring of the winding core  10 , the second tab  30  is located at the outer ring of the winding core  10 , and one of the first tab  20  and the second tab  30  is connected to the upper end of the winding core  10 , and the other of the first tab  20  and the second tab  30  is connected to the lower end of the winding core  10 . The first tab  20  is located at the outer ring of the winding core  10 , which refers to that the position where the first tab  20  and the positive electrode sheet  11 /or the negative electrode sheet  12  are connected is located at an outer ring layer of the winding core  10 , and the outer refers to a portion of the winding core close to the housing  50  of the button battery. 
     As shown in  FIG.  6    and  FIG.  7   , when the first tab  20  is located at the outer ring of the winding core  10 , the separator  13  is disposed at the outer side of the positive electrode sheet  11 /or the negative electrode sheet  12  connected to the first tab  20 ; the separator bonding layer  132  includes a first separator bonding layer located at the inner side of the first tab  20  and a second separator bonding layer located at the outer side of the first tab  20 , and the bonding force of the first separator bonding layer is greater than that of the second separator bonding layer; the separator  13  is disposed at the outer side of the positive electrode sheet  11 /negative electrode sheet  12  connected to the second tab  30 ; the separator bonding layer  132  includes a first separator bonding layer located at the inner side of the second tab  30  and a second separator bonding layer located at the outer side of the second tab  30 , and the bonding force of the first separator bonding layer is greater than that of the second separator bonding layer. When processing the first separator bonding layers, it is necessary to use a heating plate  40  to scrape the protruding ends  131  of the separator  13  at both ends of the winding core  10  from the edge of the winding core  10  toward the direction of the inner hole  14  in the center of the winding core  10 . Except for a layer of the separator  13  disposed at the outer ring of the positive electrode sheet  11 /or the negative electrode sheet  12  connected to the first tab  20  and the second tab  30 , the protruding ends  131  of the remaining separator  13  disposed at the inner rings of the positive electrode sheet  11 /or the negative electrode sheet  12  are all scraped toward the direction of the inner hole  14  in the center of the winding core  10 , so that the protruding ends  131  of the separator  13  are inclined. Then the inclined protruding ends  131  at both ends of the winding core  10  are bonded and contracted by plane hot pressing to form the first separator bonding layers, and the bonding force of the first separator bonding layer is greater than that of the second separator bonding layer. 
     Where, the bonding force refers to that after the separator bonding layer  132  is formed, the separator bonding layer  132  is separated by a force, and the amount of the force required to separate the separator bonding layer  132  represents the bonding force. The greater the bonding force, the greater the force required to separate the separator bonding layer  132 . 
     As another implementation of this embodiment, as shown in  FIG.  1    and  FIG.  2   , when the first tab  20  is located at the inner ring of the winding core  10 , the second tab  30  is located at the inner ring of the winding core  10 , one of the first tab  20  and the second tab  30  is connected to the upper end of the winding core  10 , and the other of the first tab  20  and the second tab  30  is connected to the lower end of the winding core  10 . 
     As shown in  FIG.  1    and  FIG.  2   , when the first tab  20  is located at the inner ring of the winding core  10 , the separator  13  is disposed at the inner side of the positive electrode sheet  11 /or the negative electrode sheet  12  connected to the first tab  20 ; the separator bonding layer  132  includes a second separator bonding layer located at the inner side of the first tab  20  and a first separator bonding layer located at the outer side of the first tab  20 , and the bonding force of the first separator bonding layer is greater than that of the second separator bonding layer; the second tab  30  is located at the inner ring of the winding core  10 , and the separator  13  is disposed at the inner side of the positive electrode sheet  11 /or the negative electrode sheet  12  connected to the second tab  30 ; the separator bonding layer  132  includes a second separator bonding layer located at the inner side of the second tab  30  and a first separator bonding layer located at the outer side of the second tab  30 , and the bonding force of the first separator bonding layer is greater than that of the second separator bonding layer. When processing the first separator bonding layers, it is necessary to use a heating plate  40  to scrape the protruding ends  131  of the separator  13  at both ends of the winding core  10  from the edge of the winding core  10  toward the direction of the inner hole  14  in the center of the winding core. Except for a layer of the separator  13  disposed at the inner ring of the positive electrode sheet  11 /or the negative electrode sheet  12  connected to the first tab  20  and the second tab  30 , the protruding ends  131  of the remaining separator  13  disposed at the outer rings of the positive electrode sheet  11 /or the negative electrode sheet  12  are all scraped toward the direction of the inner hole  14  in the center of the winding core  10 , so that the protruding ends  131  of the separator  13  are inclined. Then the inclined protruding ends  131  at both ends of the winding core  10  are bonded and contracted by plane hot pressing to form the first separator bonding layers. The bonding force of the first separator bonding layer is greater than that of the second separator bonding layer. The first tab  20  is located at the inner ring of the winding core  10 , which refers to that the position where the first tab  20  and the positive electrode sheet  11 /or the negative electrode sheet  12  are connected is located at an inner ring layer of the winding core  10 , and the inner refers to a portion of the winding core close to the inner hole  14 . 
     As shown in  FIG.  11   , the first tab  20  and the second tab  30  are subjected to scrapingly pressing after hot pressing, so that the separator  13  at the outermost ring is subjected to scrapingly pressing on the end faces of the separator bonding layer  132  by the first tab  20  and the second tab  30 , and the bonding force between the separator  13  at the outermost ring and the separator  13  at the secondary outer ring is smaller than the bonding force between the separators  13  at the other rings. 
     Particularly, when the first tab  20  is located at the outer ring of the winding core  10 , the second tab  30  is located at the inner ring of the winding core  10 , and one of the first tab  20  and the second tab  30  is connected to the upper end of the winding core  10  and the other one of the first and second tabs  20  and  30  is connected to the lower end of the winding core  10 , the separators  13  are respectively disposed at the outer side of the positive electrode sheet  11 /or the negative electrode sheet  12  connected to the first tab  20  and the inner side of the positive electrode sheet  11 /or the negative electrode sheet  12  connected to the second tab  30 . In this case, the separator bonding layer  132  includes a first separator bonding layer located at the inner side of the first tab  20 , a first separator bonding layer located at the outer side of the second tab  30 , a second separator bonding layer located at the outer side of the first tab  20 , and a second separator bonding layer located at the inner side of second tab  30 . The bonding force of the first separator bonding layer is greater than that of the second separator bonding layer. 
     The area of the second separator bonding layer covering the first tab  20  accounts for 5% to 30% of the area of the first tab  20 , and the area of the second separator bonding layer covering the second tab  30  accounts for 5% to 30% of the area of second tab  30 . 
     The battery cell structure of a button battery provided by the present disclosure is mounted in the housing  50  for encapsulating, the winding core  10  is connected to the metal housing  50  of the button battery through a negative electrode tab, and the winding core  10  is connected to the metal housing  50  of the button battery through a positive electrode tab. 
     In the present embodiment, as shown in  FIG.  8    and  FIG.  9   , before the separator bonding layer  132  is formed, the separator  13  has a width A of 4 mm-10 mm, and after the separator bonding layer  132  is formed, the separator  13  has a width A 2  of 3 mm-9 mm. The positive electrode sheet  11  has a width B of 2 mm-8 mm, and the negative electrode sheet  12  has a width C of 2.5 mm-8.5 mm. 
     In the present embodiment, the separator  13  may be a 5+2+2 μm macroporous separator in oil system, which has a melting point of 125° C. An aluminum foil having a thickness of 10 m can be used as the base material of the positive electrode sheet  11 , and a coating layer having a thickness of 75 μm is applied to both the front and back surfaces of the base material of the positive electrode sheet  11 . A copper foil having a thickness of 5 μm is used as the base material of the negative electrode sheet  12 , and a coating layer having a thickness of 85 μm is applied to both the front and back surfaces of the base material of the negative electrode sheet  12 . 
     Preferably, the winding core  10  has a diameter of 10 mm and a width of 5.5 mm, the separator  13  has a width A of 5.5 mm, the negative electrode sheet  12  has a width C of 4 mm, and the positive electrode sheet  11  has a width B of 3.5 mm. 
     As shown in  FIG.  11   , the present disclosure further provides a button battery, including the above battery cell structure of the button battery, and further including a housing  50 , where a holding cavity  51  for holding the battery cell structure of the button battery is disposed in the housing  50 , a housing cover for sealing the holding cavity  51  is disposed on the housing  50 , and the housing  50  is used for encapsulating the battery cell structure of the button battery therein to protect the battery cell structure of the button battery. 
     One end of the first tab  20  is connected to the positive electrode sheet  11 /or the negative electrode sheet  12 . The middle portion of the first tab  20  is bent to form a bent portion  21  that is approximately parallel to the end face of the winding core  10 , and the bent portion  21  extends toward the other end of the first tab  20 . The bent portion  21  of the first tab  20  is located on at least one end face of the winding core  10 , the bent portion  21  of the first tab  20  contacts the separator bonding layer  132 , and the bent portion  21  is electrically connected to an end face of the housing  50 . 
     Specifically, one surface of the bent portion  21  is in contact with the first separator bonding layer of the separator bonding layer  132 , and the other surface of the bent portion  21  of the first tab  20  is in contact with an end face of the housing  50  to achieve electrical connection. 
     In the existing winding core  10 , the protruding ends  131  of the separator  13  is loose and has a low strength, so that the insulating effect cannot be performed well. Therefore, it is necessary to paste insulating bonding papers on the end faces of the existing winding core  10  to insulate the first tab  20  from the two end faces of the winding core  10 . In the button battery provided by the present application, the end faces of the winding core  10  are provided with the separator bonding layer  132  wrapping the winding core  10 , the separator bonding layer  132  wraps and tightens the winding core, and the separator bonding layer  132  insulates the first tab  20  from the two end faces of the winding core. Therefore, the first tab  20  can be directly bent to contact the separator bonding layer  132 , and there is no need to use the insulating bonding paper, thereby simplifying the structure of the button battery. 
     The present disclosure further provides a manufacturing method of a battery cell structure of a button battery, as shown in  FIG.  12   , for manufacturing the above battery cell structure of the button battery, including the following steps: 
     step S 110 , providing a winding core  10 , where the winding core  10  includes a positive electrode sheet  11 , a negative electrode sheet  12  and a separator  13  separating the positive electrode sheet  11  from the negative electrode sheet  12 , and  FIG.  8    is a schematic partial structural diagram of the provided winding core  10 ; 
     step S 120 , providing a first tab  20  and a second tab  30 , where one of the first tab  20  and the second tab  30  is a positive tab, and the other of the first tab  20  and the second tab  30  is a negative tab; 
     step S 130 , welding the first tab  20  and the second tab  30 , where the positive tab in the first tab  20  and the second tab  30  is connected to the positive electrode plate  11 , and the negative tab in the first tab  20  and second tab  30  is connected to the negative electrode plate  12 ; 
     step S 140 , providing a heating plate  40  and heating the heating plate  40  to a preset temperature; 
     step S 150 , scraping, by the heating plate  40 , the separator  13  at both ends of the winding core  10  from outside to inside, so that the protruding ends  131  of the separator  13  form inclined protruding ends  131 ; 
     step S 160 , thermally pressing the inclined protruding ends  131  by the heating plate  40  to make the inclined protruding ends  131  form a separator bonding layer  132  which is sequentially bonded and contracted, and specifically to make the inclined protruding ends  131  form a first separator bonding layer which is sequentially bonded and contracted; 
     Step S 170 , scrapingly pressing the first tab  20  and the second tab  30  to make them press against the end faces of the separator bonding layer  132 ; specifically, scrapingly pressing the first tab  20  and the second tab  30  to make them press against the first separator bonding layer of the separator bonding layer  132 ; 
     Step S 180 , scrapingly pressing the separator  13  at the outermost ring/or innermost ring of the winding core  10  to make it bonded to the separator bonding layer  132 ; specifically, scrapingly pressing the separator  13  at the outermost ring/or innermost ring of the winding core  10  to make it bonded to the separator bonding layer  132  to form a second separator bonding layer. 
     The manufacturing method of the battery cell structure of the button battery provided by the present disclosure has simple manufacturing process and can be used for large-scale production, and the manufactured battery cell structure of the button battery has good safety. In the present disclosure, a hot pressing process is adopted to enable a separator  13  to form a separator bonding layer  132  at both ends of a winding core  10  to completely wrap a positive electrode sheet  11  and a negative electrode sheet  12  in a sealed region, so that the positive electrode sheet  11  and the negative electrode sheet  12  are effectively prevented from moving and shifting to contact the housing  50  of the button battery, thereby avoiding a short circuit, prolonging the service life of the button battery, ensuring the stable use in bumpy environments, and improving the use safety. 
     In step S 140 , providing a heating plate  40  and heating the heating plate  40  to a preset temperature includes: 
     providing an arc heating plate  41 , a first planar heating plate  42  and a second planar heating plate  43 , and heating the arc heating plate  41 , the first planar heating plate  42  and the second planar heating plate  43  to a preset temperature which is 100 to 150° C. 
     Preferably, the preset temperature is 122° C. to 128° C. 
     The radian of the arc heating plate  41  is 30 rad to 60 rad. 
     The arc heating plate  41 , the first planar heating plate  42  and the second planar heating plate  43  are all made of a heat-conducting material, including but not limited to a metal material, such as copper. The surface of the metal material is coated with a thermal insulation material, including but not limited to a ceramic material. 
     Preferably, the arc heating plate  41 , the first planar heating plate  42  and the second planar heating plate  43  are all made of copper, and the surfaces of the arc heating plate  41 , the first planar heating plate  42  and the second planar heating plates  43  are all coated with ceramic with a thickness of 20 μm at the portions in contact with the separator  13 . 
     In step S 150 , as shown in  FIG.  9    which is a schematic partial structural diagram of the winding core  10  after step S 150  is completed, the heating plate  40  scrapes the separator  13  at both ends of the winding core  10  from outside to inside, so that the protruding ends  131  of the separator  13  forms inclined protruding ends  131 , which includes: 
     as shown in  FIG.  2    and  FIG.  3   , the downward pressing heights of the two pairs of the first planar heating plates  42  are controlled so that the scrapers of the two pairs of the first planar heating plates  42  extend to a preset depth position in the protruding ends  131  of the separator  13 ; 
     the scrapers of the first planar heating plates  42  move toward the position of the inner hole  14  at the center of the winding core  10 , and press the protruding ends  131  laterally so that the protruding ends  131  are inclined toward the inner hole  14  at the center of the winding core  10 . Therefore, the width A 1  of the separator  13  reaches a value required in this embodiment, that is, 5 mm; alternatively, 
     as shown in  FIG.  1   , the downward pressing heights of the two pairs of the arc heating plates  41  are controlled so that the scrapers of the two pairs of the arc heating plates  41  extend to a preset depth position in the protruding ends  131  of the separator  13 ; 
     the scrapers of the arc heating plates  41  move toward the position of the inner hole  14  at the center of the winding core  10 , and presses the protruding ends  131  in arc so that the protruding ends  131  are inclined toward the inner hole  14  at the center of the winding core  10 . Therefore, the width A 1  of the separator  13  reaches a value required in this embodiment, that is, 5 mm. 
     In  FIG.  1   , a direction indicated by a straight arrow indicates a direction in which the scraper of the arc heating plate  41  scrapes the protruding ends  131  of the separator  13 . In  FIG.  2    and  FIG.  3   , a direction indicated by a straight arrow indicates a direction in which the scraper of the first planar heating plate  42  scrapes the protruding ends  131  of the separator  13 . 
     In this embodiment, as shown in  FIG.  2   , the first tab  20  and the second tab  30  are respectively located at the inner ring of the winding core  10 , the adopted heating plates  40  are two pairs of the first planar heating plates  42 , and the initial positions of the two pairs of the first planar heating plates  42  are respectively located at two end faces of the winding core  10 . The scrapers of the two pairs of the first planar heating plates  42  extend to a preset depth position in the protruding ends  131  of the separator  13 , and the two pairs of the first planar heating plates  42  move relative to each other so that the scrapers of the first planar heating plates  42  move toward the position of the inner hole  14  at the center of the winding core  10 , and press the protruding ends  131  laterally, so that the protruding ends  131  are inclined toward the inner hole  14  at the center of the winding core  10 ; 
     in another implementation of this embodiment, as shown in  FIG.  1   , the first tab  20  and the second tab  30  are respectively located at the inner ring of the winding core  10 , the adopted heating plates  40  are two pairs of the arc heating plates  41 , and the initial positions of the two pairs of the arc heating plates  41  are respectively located at the outer sides of two end faces of the winding core  10 . The scrapers of the two pairs of the arc heating plates  41  extend to a preset depth position in the protruding ends  131  of the separator  13 , and the two pairs of the arc heating plates  41  move relative to each other so that the scrapers move toward the center of the winding core  10 , so that the arc pressing protruding ends  131  are inclined toward the center of the winding core  10 . 
     In yet another implementation of this embodiment, as shown in  FIG.  3   , the first tab  20  and the second tab  30  are respectively located at the outer ring of the winding core  10 , the heating plates  40  adopt two pairs of the first planar heating plates  42 , and the initial positions of the two pairs of the first planar heating plates  42  are respectively located at two end faces of the winding core  10 . The two pairs of the first planar heating plates  42  move relative to each other, and the scrapers of the two pairs of the first planar heating plates  42  extend to a preset depth position in the protruding end  131  of the separator  13 , so that the protruding ends  131  are inclined toward the inner hole  14  at the center of the winding core  10  by pressing the protruding ends  131  laterally by the scrapers of two pairs of the first planar heating plates  42 . 
     Specifically, the scrapers of the first planar heating plates  42  and the scrapers of the arc heating plates  41  are all have a length of 20 mm and a width of 1 mm. The end faces of the scrapers of the first planar heating plates  42  and the end faces of the scrapers of the arc heating plates  41  are all have a chamfer angle of 45°. 
     In step S 160 , as shown in  FIG.  10    which is a schematic partial structural diagram of the winding core  10  after step S 160  is completed, the heating plate  40  thermally presses the inclined protruding ends  131 , so that the inclined protruding ends  131  form a separator bonding layer  132  which is sequentially bonded and contracted, which includes: 
     in  FIG.  4    and  FIG.  5   , a direction indicated by a straight arrow indicates a direction in which the second planar heating plate  43  presses. As shown in  FIG.  4    and  FIG.  5   , the second planar heating plate  43  is used to thermally press the inclined protruding ends  131 , so that the adjacent protruding ends  131  are mutually bonded and contracted to form the separator bonding layer  132  that completely wraps the positive electrode sheet  11  and the negative electrode sheet  12 . 
     Specifically, as shown in  FIG.  4   , the first tab  20  and the second tab  30  are respectively located at the outer ring of the winding core  10 , and a pair of the second planar heating plates  43  are used to thermally press the inclined protruding ends  131 . In this case, the pair of the second planar heating plates  43  may be of a solid circular structure, and the pair of the second planar heating plates  43  move towards each other, so that the adjacent protruding ends  131  are bonded to each other and contracted to form the separator bonding layer  132  that completely wraps the positive electrode sheet  11  and the negative electrode sheet  12 . 
     As shown in  FIG.  5   , the first tab  20  and the second tab  30  are respectively located in the inner ring of the winding core  10 , and a pair of the second planar heating plates  43  are used to thermally press the inclined protruding ends  131 . In this case, the pair of the second planar heating plates  43  may be of a circular structure with a hole in the center, and the pair of second planar heating plates  43  move towards each other, so that the adjacent protruding ends  131  are bonded to each other and contracted to form the separator bonding layer  132  that completely wraps the positive electrode sheet  11  and the negative electrode sheet  12 . 
     The second planar heating plate  43  adapts a circular structure with a diameter of 11 mm. 
     In this embodiment, the width A 2  of the separator  13  reaches the preset value in this embodiment, that is, 4.5 mm, by controlling the temperature and the downward pressing height of the second planar heating plate  43 , so that the adjacent protruding ends  131  are bonded to each other and contracted to form a sealed space and the positive electrode sheet  11  and the negative electrode sheet  12  are completely covered by the separator  13 . The positive electrode sheet  11  and the negative electrode sheet  12  will not contact with the housing  50  of the battery and other objects no matter how they move in the sealed region formed by the separator  13 , thus avoiding the risk of a short circuit caused by the contact of the positive electrode sheet  11  and the negative electrode sheet  12  with the metal housing  50  after they are dislocated in harsh environments, especially in bumpy environments, and greatly improving the safety of the battery cell structure of the button battery. 
     In step S 180 , scrapingly pressing the separator  13  at the outermost ring and/or the outermost ring of the winding core  10  to make it bonded to the separator bonding layer  132  includes: 
     when the first tab  20  and the second tab  30  are respectively located at the outer ring of the winding core  10 , the heating plate is a pair of the first planar heating plates  42 , which are used to scrapingly press the separator at the outermost ring of the winding core  10 , so that the separator at the outermost ring of winding core  10  is bonded to the separator bonding layer  132 , thereby improving the sealing performance of the separator bonding layer  132 ; 
     when the first tab  20  and the second tab  30  are respectively located at the inner ring of the winding core  10 , the adopted heating plate  40  is two pairs of the arc heating plates  41  or a pair of the first planar heating plates  42  to scrapingly press the separator at the innermost ring of the winding core  10 , so that the separator at the innermost ring of winding core  10  is bonded to the separator bonding layer  132 , thereby improving the sealing performance of the separator bonding layer  132 . 
     In this embodiment, as shown in  FIG.  8    and  FIG.  9   , the separator  13  has a width A of 4 mm-10 mm before the separator bonding layer  132  is formed, and the separator  13  has a width A 2  of 3 mm-9 mm after the separator bonding layer  132  is formed by scraping down and inclining the protruding ends  131  of the separator  13  and then hot pressing. 
     The positive electrode sheet  11  has a width B of 2 mm-8 mm, and the negative electrode sheet  12  has a width C of between 2.5 mm-8.5 mm. 
     After the separator bonding layer  132  is formed by hot pressing, the length of the separator  13  beyond the positive electrode sheet  11  is 20% to 60%, preferably 30% to 50%, of the length of the separator  13  beyond the positive electrode sheet  11  before the separator bonding layer  132  is formed. 
     In the description of the present disclosure, it should be understood that the used terms “center”, “length”, “width”, “thickness”, “top”, “bottom”, “upper”, “lower”, “left”, “right”, “front”, “back”, “vertical”, “horizontal”, “inner”, “outer”, “axial”, “circumferential” and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present disclosure and simplifying the description, but not for indicating or implying that the locations or elements referred to must have a specific orientation, construction, and operation, therefore, it cannot be understood as limiting the present disclosure. 
     Furthermore, the terms “first” and “second” are only used for descriptive purposes, and it cannot be understood as indicating or implying relative importance or as implying the numbers of the indicated technical features. Thus, the features defined with “first” or “second” may explicitly or implicitly include one or more of the features. In the description of the present disclosure, “a plurality of” means at least two, such as two, three, etc., unless otherwise clearly defined. 
     In the present disclosure, unless otherwise clearly specified and defined, the terms “mounted”, “connecting”, “connected” and “fixed” should be understood broadly. For example, it can be a fixed connection, a detachable connection, or an integrally connection; it can be a mechanically connection, an electrical connection or a mutual communication; it can be a directly connection, an indirectly connection through an intermediary, an internal connection between two components, or the interactive relationship between two components. For those of ordinary skill in the art, the specific meaning of the above terms in the present disclosure can be understood according to specific situations. 
     In the present disclosure, unless otherwise clearly specified and defined, the description of a first feature being “over” or “under” a second feature may include the first and second features being in direct contact, or the first and second features being in non-direct contact through another feature between them. Also, the description of a first feature being “on”, “above”, and “on top of” a second feature include the first feature being directly above and diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. The description of a first feature being “under”, “below” and “on the bottom of” a second feature include the first feature being directly below and diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature. 
     Finally, it should be noted that the foregoing embodiments are merely intended for describing the technical solutions of the present disclosure rather than limiting the present disclosure; although the present disclosure is described in detail with reference to the foregoing embodiments, persons of ordinary skill in the art should understand that the technical solutions described in the foregoing embodiments may be modified or made equivalent substitutions to some or all technical features thereof; and these modifications and substitutions shall not cause the essence of the corresponding technical solutions to depart from the scope of the technical solutions of embodiments of the present disclosure.