Patent Publication Number: US-2023146401-A1

Title: Electrode plate, electrode assembly containing same, and battery

Description:
CROSS REFERENCE TO THE RELATED APPLICATIONS 
     This application is a continuation under 35 U.S.C. § 120 of international patent application PCT/CN2020/099584 filed on Jun. 30, 2020, the entire contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This application relates to the field of batteries, and in particular, to an electrode plate, an electrode assembly containing the electrode plate, and a battery containing the electrode assembly. 
     BACKGROUND 
     By virtue of a high energy density, a high working voltage, a long cycle life, environmental friendliness, safety, and other advantages, batteries have been widely used in various electronic products. Therefore, higher requirements are imposed on the safety of the batteries. In a jelly-roll electrode assembly, especially when a tab is disposed near a bend region of the electrode assembly, a protection adhesive layer disposed on an electrode plate is usually bent together with the bending of the electrode plate. Therefore, a sealant on a tab bonded to the protection adhesive layer is pulled and warped, thereby interfering with the sealing of the electrode assembly and even causing risks of electrolyte leakage, and in turn, impairing the safety of the battery. 
     SUMMARY 
     In view of the foregoing situation, it is necessary to provide an electrode plate that improves safety. 
     In addition, it is necessary to provide an electrode assembly containing the electrode plate, and a battery containing the electrode assembly. 
     An electrode plate according to this application includes an electrode plate body, a tab, a first adhesive layer, and a second adhesive layer. The tab includes a connecting portion and an extending portion connected to the connecting portion. The connecting portion overlaps and is connected to the electrode plate body. The extending portion protrudes from the connecting portion out of one side of the electrode plate body along a first direction. The first adhesive layer is disposed on the extending portion. 
     The second adhesive layer includes a first part and a second part. The first part is bonded to a surface of the electrode plate body and covers the connecting portion. The second part is formed by extending the first part from a side near the first adhesive layer along the first direction and is bonded to the first adhesive layer. In a second direction perpendicular to the first direction, a width of the second part is less than a width of the first part. 
     As a technical solution of this application, the second part is directly bonded to the first adhesive layer, or the second part is indirectly bonded to the first adhesive layer through a transition section. The transition section is formed by extending the second part along the first direction. 
     As a technical solution of this application, along the second direction, a width of the transition section is identical to the width of the first part, or the width of the transition section is identical to the width of the second part. 
     As a technical solution of this application, in the first direction, the second part at least partly extends beyond the electrode plate body. 
     As a technical solution of this application, a junction between the first part and the second part is a chamfered, right-angled, acute-angled, or obtuse-angled. 
     As a technical solution of this application, the tab includes two extending portions. The two extending portions are disposed on two opposite sides of the electrode plate body respectively. The second adhesive layer includes two second parts. The two second parts are disposed on two opposite sides of the first part respectively. 
     As a technical solution of this application, the second part is disposed in a middle region of the first part, so that the first part extends beyond the second part at both ends along the second direction. 
     As a technical solution of this application, the second adhesive layer further includes a third part. The third part is formed by extending the second part along the second direction. The third part is bonded to the first adhesive layer. The third part is at least partly disconnected from the first part. 
     As a technical solution of this application, the third part is connected to the first part. A plurality of gaps are disposed at intervals at a junction between the third part and the first part to form a pre-cut-off structure at the junction. 
     An electrode assembly according to this application includes a first electrode plate, a second electrode plate, and a separator located between the first electrode plate and the second electrode plate. The first electrode plate, the separator, and the second electrode plate are stacked and then wound to form an electrode assembly. The first electrode plate is the electrode plate described above. 
     As a technical solution of this application, the electrode assembly includes a bend region. A protruding section of the first part beyond the second part is disposed in the bend region. 
     As a technical solution of this application, the protruding section of the first part beyond the second part is disposed in the bend region, and the third part is separated from the first part. 
     A battery according to this application contains the electrode assembly described above. 
     In the electrode plate, the electrode assembly containing the electrode plate, and the battery containing the electrode assembly according to this application, the width of the second part bonded to the first adhesive layer in the second adhesive layer in the second direction is less than the width of the first part bonded to the electrode plate body in the second adhesive layer in the second direction. This reduces the degree to which the second adhesive layer interferes with the first adhesive layer during winding of the electrode plate, and reduces the risk of warping the first adhesive layer when the second adhesive layer bends together with the bending of the electrode plate body, thereby reducing the impact caused to subsequent sealing of the electrode plate, reducing problems such as poor sealing or even electrolyte leakage, improving the yield rate of the subsequent sealing, the reliability, and safety. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic structural diagram of an electrode plate according to an embodiment of this application; 
         FIG.  2    is a schematic structural diagram of an electrode plate according to an embodiment of this application; 
         FIG.  3    is a schematic structural diagram of an electrode plate according to an embodiment of this application; 
         FIG.  4    is a schematic structural diagram of an electrode plate according to an embodiment of this application; 
         FIG.  5    is a schematic structural diagram of an electrode plate according to an embodiment of this application; 
         FIG.  6    is a schematic structural diagram of an electrode plate according to an embodiment of this application; 
         FIG.  7    is a schematic structural diagram of an electrode plate according to an embodiment of this application; 
         FIG.  8    is a schematic structural diagram of an electrode plate according to an embodiment of this application; 
         FIG.  9    is a schematic structural diagram of an electrode plate according to an embodiment of this application; 
         FIG.  10    is a schematic structural diagram of an electrode plate according to an embodiment of this application; 
         FIG.  11    is a schematic structural diagram of an electrode assembly according to an embodiment of this application; 
         FIG.  12    is a schematic structural diagram of an electrode assembly according to an embodiment of this application; and 
         FIG.  13    is a schematic structural diagram of an electrode assembly according to an embodiment of this application. 
     
    
    
     REFERENCE NUMERALS OF MAIN COMPONENTS 
       
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Electrode plate 
                 100 
               
               
                   
                 Electrode plate body 
                 10 
               
               
                   
                 Tab 
                 20 
               
               
                   
                 First adhesive layer 
                 30 
               
               
                   
                 Second adhesive layer 
                 40 
               
               
                   
                 Connecting portion 
                 21 
               
               
                   
                 Extending portion 
                 23 
               
               
                   
                 First direction 
                 X 
               
               
                   
                 First part 
                 41 
               
               
                   
                 Second part 
                 43 
               
               
                   
                 Second direction 
                 Y 
               
               
                   
                 End face 
                 430 
               
               
                   
                 Stepped portion 
                 45 
               
               
                   
                 Stepped face 
                 410 
               
               
                   
                 Third part 
                 47 
               
               
                   
                 Gap 
                 470 
               
               
                   
                 Electrode assembly 
                 600 
               
               
                   
                 First electrode plate 
                 601 
               
               
                   
                 Second electrode plate 
                 603 
               
               
                   
                 Separator 
                 605 
               
               
                   
                 Bend region 
                 61 
               
               
                   
                 Flat region 
                 63 
               
               
                   
                   
               
            
           
         
       
     
     This application is further described below with reference to the following specific embodiments and the foregoing drawings. 
     DETAILED DESCRIPTION 
     The following describes the technical solutions in the embodiments of this application clearly and thoroughly with reference to the drawings herein. Evidently, the described embodiments are merely a part of but not all of the embodiments of this application. 
     Unless otherwise defined, all technical and scientific terms used herein have the same meanings as what is normally ascribed to such terms by a person skilled in the technical field of this application. The terms used in the specification of this application are merely intended to describe specific embodiments but not to limit this application. 
     The following describes some embodiments of this application in detail with reference to drawings. To the extent that no conflict occurs, the following embodiments and the features in the embodiments may be combined with each other. 
     Referring to  FIG.  1   , according to an embodiment of this application, an electrode plate  100  includes an electrode plate body  10 , a tab  20 , a first adhesive layer  30 , and a second adhesive layer  40 . The tab  20  includes a connecting portion  21  and an extending portion  23  connected to the connecting portion  21 . The connecting portion  21  overlaps and is connected to the electrode plate body  10 . The extending portion  23  protrudes from the connecting portion  21  out of one side of the electrode plate body  10  along a first direction X, and is configured to be electrically connected to other electronic components. The first adhesive layer  30  is disposed on the extending portion  23 . The second adhesive layer  40  includes a first part  41  and a second part  43 . The first part  41  is bonded to a surface of the electrode plate body  10  and covers the connecting portion  21 . The second part  43  is formed by extending the first part  41  from a side near the first adhesive layer  30  along the first direction X and is bonded to the first adhesive layer  30 . In a second direction Y perpendicular to the first direction X, a width of the second part  43  is less than a width of the first part  41 . The first adhesive layer  30  is thermally melted and thoroughly bonded to a sealing film when the electrode plate  100  is subsequently sealed in the sealing film to form a battery, so as to implement sealing at the tab  20 . When covering the connecting portion  21 , the second adhesive layer  40  can cover burrs at a weld between the connecting portion  21  and the electrode plate body  10 , thereby reducing the risk that the burrs pierce the sealing film subsequently and other risks such as a short circuit caused by the burrs. 
     In addition, during formation of an electrode assembly or a battery, the second adhesive layer  40  can further reduce the risk of a contact and short circuit between the positive electrode plate and the negative electrode plate. The width of the second part  43  bonded to the first adhesive layer  30  in the second adhesive layer  40  in the second direction Y is less than the width of the first part  41  bonded to the electrode plate body  10  in the second adhesive layer  40  in the second direction Y. This reduces the degree to which the second adhesive layer  40  interferes with the first adhesive layer  30  during winding of the electrode plate  100 , and reduces the risk of warping the first adhesive layer  30  when the second adhesive layer  40  bends together with the bending of the electrode plate body  10 , thereby reducing the impact caused to subsequent sealing of the electrode plate, reducing problems such as poor sealing or even electrolyte leakage, improving the yield rate of the subsequent sealing, the reliability, and safety. 
     The first adhesive layer  30  may be, but without being limited to, green adhesive or hot melt adhesive, and may be other adhesive materials used as a sealant. The thickness of the first adhesive layer  30  is not limited herein, and may be adjusted as required. 
     The second adhesive layer  40  may be a bonding layer or adhesive tape. The adhesive tape includes a substrate layer and a bonding layer disposed on the substrate layer. The adhesive tape may be single-sided tape or double-sided tape. 
     Preferably, the thickness of the second adhesive layer  40  is enough to prevent the burrs at the weld between the connecting portion  21  and the electrode plate body  10  from piercing the second adhesive layer  40 . 
     Referring to  FIG.  2   ,  FIG.  3   , and  FIG.  4   , the first part  41  may extend beyond an edge of the electrode plate body  10  (as shown in  FIG.  2   ) and overlap the region (as shown in  FIG.  3   ) of the electrode plate body  10  except the edge, or may be aligned with the edge of the electrode plate body  10  (as shown in  FIG.  4   ). Preferably, the first part  41  is aligned with the edge of the electrode plate body  10  (as shown in  FIG.  4   ) or extends beyond the edge of the electrode plate body  10  (as shown in  FIG.  2   ), thereby further reducing the degree to which the first part  41  interferes with the first adhesive layer  30  due to bending of the electrode plate body. More preferably, the first part  41  extends beyond the edge of the electrode plate body  10  (as shown in  FIG.  2   ), thereby further reducing the risk of a contact and short circuit between positive electrode plate and the negative electrode plate while reducing the degree to which the second adhesive layer  40  interferes with the first adhesive layer  30 . 
     An end face  430  of the second part  43  may be at a right angle (as shown in  FIG.  2   ), acute angle, or obtuse angle to the first part  41 . 
     In some embodiments, the junction between the first part  41  and the second part  43 , that is, the junction between the first part  41  and the end face  430  may be chamfered or rounded. Preferably, referring to  FIG.  5   , the junction between the first part  41  and the end face  430  is rounded, so as to reduce stress concentration at the junction between the first part  41  and the end face  430  during subsequent winding of the electrode plate  100 . 
     In some embodiments, referring to  FIG.  6   , the tab  20  may include two extending portions  23 . The two extending portions  23  are disposed on two opposite sides of the electrode plate body  10  respectively. According to an embodiment of this application, the two extending portions  23  may extend to the same connecting portion  21 . According to another embodiment of this application, the two extending portions  23  may extend to the two connecting portions  21  respectively. The first adhesive layer  30  is disposed on each extending portion  23 . 
     The second adhesive layer  40  correspondingly includes two second parts  43 . The two second parts  43  are disposed on two opposite sides of the first part  41  respectively, and are bonded to the first adhesive layers  30  on adjacent extending portions  23  respectively. In the second direction Y, the width of each second part  43  is less than the width of the first part  41 . In this embodiment, the end faces  430  of the two second parts  43  are flush with each other in the second direction Y. In some embodiments, the end faces  430  of the two second parts  43  may be not flush with each other in the second direction Y. 
     According to an embodiment of this application, a structure of a stepped portion  45  may be formed between each of the two second parts  43  and the first part  41 , and the two stepped portions are of the same structure. In some embodiments, a structure of a stepped portion  45  may be formed between each of the two second parts  43  and the first part  41 , and the two stepped portions are of different structures, as shown in  FIG.  7   . 
     Referring to  FIG.  1   , one stepped portion  45  exists between the first part  41  and each of the second parts  43 . In some embodiments, referring to  FIG.  8   , two stepped portions  45  may exist between the first part  41  and each of the second parts  43 . The two stepped portions  45  are located on two sides of the second part  43  respectively along the second direction Y, thereby facilitating the winding of the electrode plate  100 . The widths of stepped faces  410  of the two stepped portions  45  in the second direction Y may be the same or different. 
     In some embodiments, referring to  FIG.  9    and  FIG.  10   , the second adhesive layer  40  may further include a third part  47 . The third part  47  is formed by extending the second part from the end face  430  along the second direction Y. The third part  47  is bonded to the first adhesive layer  30 , and the third part  47  is at least partly disconnected from the stepped face  410 . The third part  47  can further reduce the risk of short circuits. 
     As shown in  9 , the third part  47  is connected to the first part  41 . A plurality of gaps  470  are disposed at intervals at a junction between the third part  47  and the first part  41  to form a pre-cut-off structure at the junction. During winding of the electrode plate  100 , the third part  47  is separated from the first part  41  under the action of a force. 
     Each gap  470  may be, but without being limited to, a cross section, a circular hole, a bar hole, a square hole, a prismatic hole, or another regular or irregular hole. The number of the gaps  470  is set as required. The spacing between any two adjacent gaps  470  may also be set as required, details of which are omitted here. 
     As shown in  FIG.  10   , the third part  47  is fully disconnected, that is, separated, from the first part  41 , thereby preventing the first part  41  from directly acting on the third part  47  and reducing the degree of interfering with the first adhesive layer  30 . 
     In some embodiments, when the second adhesive layer  40  includes at least two stepped portions  45 , the third part  47  is disposed on at least one of the end faces  430 . When the second adhesive layer  40  includes at least two third parts  47 , the structures between any two of the third parts  47  and an adjacent first part  41  may be identical or different. 
     The electrode plate  100  is applied to an electrode assembly. Referring to  FIG.  11    and  FIG.  12   , according to an embodiment of this application, the electrode assembly  600  includes a first electrode plate  601 , a second electrode plate  603 , and a separator  605  located between the first electrode plate  601  and the second electrode plate  603 . The first electrode plate  601 , the separator  605 , and the second electrode plate  603  are stacked and then wound to form the electrode assembly  600 . 
     In this embodiment, the electrode plate  100  serves as the first electrode plate  601 . 
     The electrode assembly  600  includes a bend region  61  and a flat region  63  connected to the bend region  61 . The tab  20  is disposed in the flat region  63 . 
     A region corresponding to the second part  43  in the first part  41  is disposed in the flat region  63 . A protruding section of the first part  41  beyond the second part  43  is located on a side that is of the second part  43  and that is close to the bend region  61 . 
     In some embodiments, referring to  FIG.  12   , at least a part of the protruding section of the first part  41  beyond the second part  43  may be disposed in the bend region  61 , as long as it is ensured that the region corresponding to the second part  43  in the first part  41  is disposed in the flat region  63 , thereby reducing the degree to which the second adhesive layer  40  interferes with the first adhesive layer  30  during winding of the electrode plate  100 . 
     In some embodiments, referring to  FIG.  13   , when the electrode plate  100  applied to the electrode assembly  600  further includes the third part  47 , if at least a part of the protruding section of the first part  41  beyond the second part  43  is disposed in the bend region  61 , the third part  47  is separated from the part of the protruding section of the first part  41  beyond the second part  43 , where that part is disposed in the bend region  61 . 
     In some embodiments, the structures of the first adhesive layer  30  and the second adhesive layer  40  in the electrode plate  100  as well as the positional relationship between each adhesive layer and the tab or the electrode plate body is also applicable to the second electrode plate  603 . 
     The electrode assembly  600  is applied to an electrochemical device (not shown in the drawing). The electrochemical device may be, but without being limited to, a battery. 
     In the electrode plate, the electrode assembly containing the electrode plate, and the battery containing the electrode assembly according to this application, the width of the second part  43  bonded to the first adhesive layer  30  in the second adhesive layer  40  in the second direction Y is less than the width of the first part  41  bonded to the electrode plate body  10  in the second adhesive layer  40  in the second direction Y. This reduces the degree to which the second adhesive layer  40  interferes with the first adhesive layer  30  during winding of the electrode plate  100 , and reduces the risk of warping the first adhesive layer  30  when the second adhesive layer  40  bends together with the bending of the electrode plate body  10 , thereby reducing the impact caused to subsequent sealing of the electrode plate, reducing problems such as poor sealing or even electrolyte leakage, improving the yield rate of the subsequent sealing, the reliability, and safety. 
     Various modifications and variations may be made by a person of ordinary skill in the art based on the technical conception hereof, and all such modifications and variations still fall within the protection scope of this application.