Patent Publication Number: US-2023136533-A1

Title: New type of cap for cylindrical lithium battery and new type of cylindrical lithium battery

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a National Stage Appl. filed under 35 USC 371 of International Patent Application No. PCT/CN2021/111309 with an international filing date of Aug. 6, 2021, designating the United States, now pending, which claims the priority of the Chinese Patent Application No. 202022454119.X, filed on Oct. 29, 2020, the entire contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present application relates to the field of lithium battery technologies, and more particularly, to a new type of cap for a cylindrical lithium battery and a new type of cylindrical lithium battery. 
     BACKGROUND 
     The existing cap for a cylindrical lithium battery includes a top cover, an explosion-proof disc, a spacer ring, a connection piece and a seal ring. The top cover is sequentially connected with the explosion-proof disc, the spacer ring and the connection piece to form an inner core of the cap, and the seal ring is sleeved on the periphery of the inner core of the cap. The cap for the cylindrical lithium battery effectively reduces formation of aluminum molten beads and improves safety performance of the overall battery pack. However, the existing cylindrical battery cap has many components, and each component needs to be matched layer by layer, resulting in a high internal resistance of the cylindrical battery cap. In addition, when the internal pressure of the battery becomes too high, the notch on the explosion-proof disc, under the pressure of the top cover structure, cannot be broken in time, which may easily lead to a risk of thermal runaway of the battery and cause a safety hazard. 
     TECHNICAL PROBLEM 
     An objective of embodiments of the present application is to provide a new type of cap for the cylindrical lithium battery, aiming to solve the problems in the existing cylindrical battery caps that when the internal pressure of the battery is too high, the notch on the explosion-proof disc, under the pressure of the top cover structure, cannot be broken in time, which may easily lead to the risk of thermal runaway of the battery, meanwhile, the cap, in use, has a large resistance, and lacks of a positive welding platform. 
     TECHNICAL SOLUTIONS 
     In order to achieve the above objective, a solution adopted in the present application is to provide a new type of cap for the cylindrical lithium battery, which includes: a steel sheet, an explosion-proof disc, a connection piece, a spacer ring, and a seal ring. The steel sheet is defined with a through hole. The explosion-proof disc is arranged on one side of the steel sheet, and the explosion-proof disc is provided with a wrap edge. The wrap edge is extended from an edge of the steel sheet to another side of the steel sheet and then to an edge of the through hole. A middle portion of the connection piece is in contact with a middle portion of the explosion-proof disc. The spacer ring is arranged between the explosion-proof disc and the connection piece. The seal ring is arranged around the explosion-proof disc, the connection piece and the spacer ring. 
     Further, the explosion-proof disc is recessed toward the connection piece to form a groove, and the spacer ring is sleeved on a periphery of the groove. 
     Further, the edge of the through hole is provided with a flange, and the flange is in contact with an inner wall of the groove. 
     Further, the explosion-proof disc is provided with a rupture score line. 
     Further, the rupture score line is arranged on a side of the groove facing the connection piece. 
     Further, the spacer ring is provided with a support portion supported on an outer side of a bottom of the groove. 
     Further, an edge of the connection piece is provided with a bend portion, and the spacer ring is provided with an annular slot matching with the bend portion to form an engagement. 
     Further, the seal ring is provided with a wrap portion, and the wrap portion is wrapped on an outer side of the explosion-proof disc. 
     Further, the seal ring is a plastic seal ring. 
     In accordance with an embodiment of the present application, a new type of cylindrical lithium battery is also provided, which includes the new type of cap for the cylindrical lithium battery described in any of the above embodiments. 
     BENEFICIAL EFFECTS 
     Beneficial effect of the new type of cap for the cylindrical lithium battery provided by the present application is that: the new type of cap for the cylindrical lithium battery of the present application, compared with the existing technologies, removes the steel cap by defining a through hole on the steel sheet. The wrap edge of the explosion-proof disc is extended to the edge of the through hole on the steel sheet, so that the external aluminum wire, when being welded, can be welded on the wrap edge of the aluminum explosion-proof disc, which reduces the contact resistance between the aluminum wire and the nickel-plated steel cap in the past. Meanwhile, a sufficient explosion venting area is formed at the through hole. When the internal pressure of the battery becomes too high, the notch on the explosion-proof disc will be broken, then the explosion-proof disc is broken, and the air flow will escape from the through-hole area of the steel sheet to ensure the safety of the battery, which avoids the risk of thermal runaway of the battery that may be easily caused by the nickel-plated steel cap used in the existing technologies, when the internal pressure of the battery is too high. At the same time, in the present application, the steel cap in the cap is removed, thereby effectively reducing the contact resistance of the cap, and the wrap edge is extended to the through hole of the steel sheet, which can ensure the structural strength of the cap. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to illustrate the solutions in the embodiments of the present application more clearly, the following briefly introduces the drawings that need to be used in description of the embodiments or the existing technologies. Obviously, the drawings in the following description are merely some embodiments of the present application. For those of ordinary skill in the art, other drawings may also be obtained according to these drawings without any creative effort. 
         FIG.  1    is a schematic cross-sectional structural diagram of a new type of cap for a cylindrical lithium battery in accordance with an embodiment of the present application; 
         FIG.  2    is an enlarged structural representation of portion A taken from  FIG.  1   ; and 
         FIG.  3    is a schematic structural diagram of a connection piece of the new type of cap for the cylindrical lithium battery in accordance with an embodiment of the present application. 
     
    
    
     Reference symbols involved in the above drawings are listed as follows: 
       10 —steel sheet;  11 —through hole;  12 —flange; 
       20 —explosion-proof disc;  21 —wrap edge;  22 —groove;  23 —rupture score line; 
       30 —spacer ring;  31 —support portion;  32 —ring groove; 
       40 —connection piece;  41 —bend portion; 
       50 —seal ring;  51 —wrap portion; and 
       60 —cylindrical shell. 
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     In order to make the problems to be solved, solutions and beneficial effects of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are intended only to explain the present application, but not to limit the present application. 
     It should he noted that when an element is referred to as being “fixed to” or “arranged/disposed on” another element, it can be directly or indirectly on the other element. When an element is referred to as being “connected to” another element, it can be directly or indirectly connected to the other element. 
     It should be understood that the terms indicating the orientation or positional relationship, such as “upper”, “lower”, “front”,“rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, etc. are based on the orientation or positional relationship shown in the drawings, which are used only for convenience of describing the present application and simplifying the description, rather than indicating or implying the device or element: referred to must have a particular orientation, he constructed and operated in a particular orientation, and therefore should not be construed as limitations to the present application. 
     In addition, the terms “first” and “second” are used only for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of the indicated features. Thus, a feature defined with “first” or “second” may expressly or implicitly include one or more of that feature. In the description of the present application, the phase “a/the plurality of” means two or more, unless otherwise expressly and specifically defined. 
     In order to illustrate the solutions described in the present application, a detailed description is given below with reference to the specific drawings and embodiments. 
     As shown in  FIGS.  1  to  3   , an embodiment of the present application provides a new type of cap for a cylindrical lithium battery, which includes a steel sheet  10 , an explosion-proof disc  20 , a connection piece  40 , a spacer ring  30  and a seal ring  50 . The steel sheet  10  is defined with a through hole  11 . The explosion-proof disc  20  is arranged on one side of the steel sheet  10 , and the explosion-proof disc  20  is provided with a wrap edge  21 . The wrap edge  21  is configured to extend from an edge of the steel sheet  10  to another side of the steel sheet  10  and then to the edge of the through hole  11 . The middle portion of the connection piece  40  is in contact with the middle portion of the explosion-proof disc  20 . The spacer ring  30  is arranged between the explosion-proof disc  20  and the connection pieces  40 . The seal ring  50  is arranged around the explosion-proof disc  20 , the connection piece  40  and the spacer ring  30 . 
     In the new type of cap for the cylindrical lithium battery provided in this embodiment, the steel sheet  10  is defined with the through hole  11 , such that the steel cap can be removed from the cap. The wrap edge  21  of the explosion-proof disc  20  is extended to the edge of the through hole  11  on the steel sheet  10 , so that the external aluminum wire, when being welded, can be welded on the wrap edge  21  of the aluminum explosion-proof disc  20 , which reduces the contact resistance between the aluminum wire and the nickel-plated steel cap in the past. Meanwhile, a sufficient explosion venting area is formed at the through hole  11 , when the internal pressure of the battery becomes too high, the notch on the explosion-proof disc  20  will be broken, then the explosion-proof disc  20  is broken, and the air flow will escape from the through-hole area of the steel sheet to ensure the safety of the battery, such that the risk of thermal runaway of the battery that may be easily caused by the nickel-plated steel cap used in the existing technologies, when the internal pressure of the battery is too high, can be avoided. At the same time, in the present application the steel cap is removed from the cap, thereby effectively reducing the resistance of the cap, and the wrap edge  21  is extended to the through hole  11  of the steel sheet  10 , which can ensure the structural strength of the cap. 
     It should be noted that the explosion-proof disc  20  may be made of aluminum material. 
     In some embodiments of the present application, optionally, as shown in  FIG.  1    and  FIG.  2   , the explosion-proof disc  20  is recessed toward the connection piece  40  to form a groove  22 , and the spacer ring  30  is sleeved on the periphery of groove  22 . 
     In this embodiment, the groove  22  is arranged so that the spacer ring  30  is annularly attached to the periphery of the groove  22 , that is, the spacer ring  30  is attached to a side of the explosion-proof disc  20  facing away from the steel sheet  10 . The groove  22  has a simple structure, which is convenient for the assembly of the spacer ring  30 . Meanwhile, the position of the groove  22  and the through hole  11  forms an explosion venting area, and the bottom of the groove  22  is connected to the connection piece  40 , which enables the connection piece  40  to bear the force on the explosion-proof piece  20 , when the internal pressure of the battery is too high, so that the explosion-proof disc  20  can be broken, thereby facilitating the gas exhaust and pressure relief. 
     Further, as shown in FIG,  1 , the bottom of the groove  22  is arc-shaped, so that the outer side of the bottom of the groove  22  is connected to the middle portion of the connection piece  40 . 
     In some embodiments of the present application, optionally, as shown in  FIG.  1    and  FIG.  2   , the edge of the through hole  11  is provided with a flange  12 , and the flange  12  is arranged in contact with an inner wall of the groove  22 . 
     In this embodiment, the edge of the through hole  11  forms the flange  12 , that is, the inner edge of the steel sheet  10  forms a flange  12  bent in a direction towards the explosion-proof disc  20 , and the flange  12  abuts against the inner wall of the groove  22 , thereby improving the fixation of the steel sheet  10  and ensuring the overall structural strength of the product. 
     In some embodiments of the present application, optionally, as shown in  FIG.  1    and  FIG.  2   , a rupture score line  23  is provided on the explosion-proof disc  20 . 
     In this embodiment, due to the arrangement of the rupture score line  23 , the air flow is more likely to break through the rupture score line  23  on the explosion-proof disc  20  when the air pressure inside the battery is too high, then the explosion-proof disc  20  is broken, and the air flow will escape from the rupture area to ensure safety of the battery. 
     In the above embodiment of the present application, optionally, as shown in  FIG.  1    and  FIG.  2   , the rupture score line  23  is provided on the side of the groove  22  facing the connection piece  40 . 
     In this embodiment, the rupture score line  23  is provided on the side of the groove  22  facing the connection piece  40 , that is, the rupture score line  23  is located on the side where the explosion-proof disc  20  contacts the connection piece  40 . Therefore, when the connection piece  40  applies a pressure in the direction towards the groove  22  due to gas pressure accumulation inside the battery, the rupture score line  23  of the explosion-proof disc  20  is more likely to break under the pressure of the flange  12  of the steel sheet  10 , ensuring the rupture and gas exhaust can be carried out in time. In addition, the flange  12  of the steel sheet  10  is in contact with the inner wall of the groove  22  of the explosion-proof disc  20 , and is arranged close to the rupture score line  23 , such that the occurrence of the rupture score line  23  of the explosion-proof disc  20 , in the absence of the pressure of the steel sheet  10  and the flange  12 , being easy to inflate upward to produce flatulence, resulting in the rupture score line  23  being difficult to break, can be avoided, thereby avoiding thermal runaway of the battery, ensuring the safety performance of the battery, and meeting the needs of customers. 
     In some embodiments of the present application, optionally, as shown in  FIG.  1    and  FIG.  2   , the spacer ring  30  is provided with a support portion  31  that is supported on the outer side of the bottom of the groove  22 . 
     In this embodiment, the support portion  31  on the spacer ring  30  is arranged so that the support portion  31  is supported between the outer corners of the groove  22  and the connection piece  40 , such that the spacer ring  30  is completely fitted between the explosion-proof disc  20  and the connection piece  40 . 
     In some embodiments of the present application, optionally, as shown in  FIG.  1    and  FIG.  3   , the edge of the connection piece  40  is provided with a bend portion  41 , and the spacer ring  30  is provided with an annular slot  32  matching with the shape of the bend portion  41  to form an engagement. 
     In this embodiment, the edge of the connection piece  40  is bent to form the bend portion  41 , and the annular slot  32  is formed on the side of the spacer  30  facing the connection piece  40 , so that the bend portion  41  is engaged with the annular slot  32 , which facilitates the positioning and assembly of the spacer ring  30 , and improves the assembly efficiency of the spacer ring  30 , thereby improving the production efficiency of the battery, reducing the production cost of the battery, and improving the market competitiveness of the battery product. 
     In some embodiments of the present application, optionally, as shown in  FIG.  1    and  FIG.  2   , the seal ring  50  is provided with a wrap portion  51 , and the wrap portion  51  wraps on the explosion-proof disc  20  from the outside. 
     Optionally, the seal ring  50  is a plastic seal ring  50 . 
     In this embodiment, the seal ring  50  may be made of a plastic material, and the wrap portion  51  is configured to crimp the wrap edge  21  of the explosion-proof disc  20  to improve the sealing effect. 
     As shown in  FIG.  1    and  FIG.  2   , an embodiment of the present application further provides a new type of cylindrical lithium battery, which includes the new type of cap for the cylindrical lithium battery described in any of the above embodiments. 
     Optionally, a cylindrical casing  60  of the new type of cylindrical lithium battery is fixedly connected to the seal ring  50  and is sleeved on the periphery of the new type of cap for the cylindrical lithium battery. 
     The new type of cylindrical lithium battery in accordance with embodiment of the present application has the new type of cap for the cylindrical lithium battery described in any of the above embodiments, and therefore, has all the beneficial effects of the new type of cap for the cylindrical lithium battery, which will not be repeated here. 
     In conclusion, the new type of cap for the cylindrical lithium battery provided by the embodiment of the present application removes the steel cap by defining a through hole on the steel sheet, and the wrap edge of the explosion-proof disc is extended to the edge of the through hole on the steel sheet, so that the external aluminum wire when being welded, can be welded on the wrap edge of the aluminum explosion-proof disc, which reduces the contact resistance between the aluminum wire and the nickel-plated steel cap in the past. Meanwhile, a larger explosion venting area is formed at the through hole, when the internal pressure of the battery becomes too high, the notch on the explosion-proof disc will be broken, then the explosion-proof disc is broken, and the air flow will escape from the through-hole area of the steel sheet to ensure the safety of the battery, so that the risk of thermal runaway of the battery that may be easily caused by the nickel-plated steel cap used in the existing technologies, when the internal pressure of the battery is too high, can be avoided. At the same time, in the present application, the steel cap in the cap is removed, thereby effectively reducing the contact resistance of the cap, and the wrap edge  21  is extended to the through hole  11  of the steel sheet  10 , which can ensure the structural strength of the cap. 
     The above descriptions are only optional embodiments of the present application, and are not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included within the protection scope of the present application.