Patent Publication Number: US-2023135786-A1

Title: Cylindrical battery

Description:
TECHNICAL FIELD 
     The present disclosure generally relates to a cylindrical battery. 
     BACKGROUND ART 
     In a cylindrical battery, a sealing assembly that seals an opening of an exterior housing can is fixed by crimping to the opening of the exterior housing can with a gasket interposed between the sealing assembly and the exterior housing can (for example, PATENT LITERATURE 1). In a manufacturing process of a cylindrical battery, an electrode assembly is first inserted into an exterior housing can, a grooved part for supporting a sealing assembly is next formed in the vicinity of an opening of the exterior housing can, and then an electrolyte is injected into the exterior housing can. The injected electrolyte gradually saturates the electrode assembly, and a liquid level position of the electrolyte falls from above to below the grooved part. At this time, the electrolyte may adhere to and remain on an inner peripheral face above the grooved part of the exterior housing can. 
     CITATION LIST 
     Patent Literature 
     
         
         PATENT LITERATURE 1: International Publication No. WO 2016/157749 
       
    
     SUMMARY 
     Technical Problem 
     In the manufacturing process of a cylindrical battery, when the sealing assembly is fixed by crimping with the gasket interposed between the sealing assembly and the exterior housing can in a state where the electrolyte adheres to the inner peripheral face above the grooved part of the exterior housing can, the adhered electrolyte may leak out to outside of the battery. The leaked electrolyte causes rust to form on the exterior housing can and the sealing assembly. The leakage of the electrolyte causes variations in electrolyte amount of the cylindrical battery. 
     It is an advantage of the present disclosure to provide a cylindrical battery that can reduce leakage of an electrolyte to outside of the battery. 
     Solution to Problem 
     The cylindrical battery of an aspect of the present disclosure is a cylindrical battery comprising: an electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed between the positive electrode and the negative electrode; an electrolyte; a bottomed cylindrical exterior housing can that houses the electrode assembly and the electrolyte; a sealing assembly that seals an opening of the exterior housing can; and an annular gasket that is interposed between the exterior housing can and the sealing assembly, the sealing assembly being fixed by crimping to an opening end of the exterior housing can with the gasket interposed between the sealing assembly and the exterior housing can, wherein a projection projecting outward in a radial direction is formed on an outer peripheral face of the gasket, and the projection comes into abutment with an inner peripheral face of the opening end of the exterior housing can. 
     Advantageous Effects of Invention 
     According to an aspect of the present disclosure, it is possible to reduce the leakage of the electrolyte to the outside of the battery. This can reduce variations in electrolyte amount of the cylindrical battery. 
    
    
     
       BRIEF DESCRIPTION OF DRAWING 
         FIG.  1    is a sectional view of a cylindrical battery of an example of an embodiment. 
         FIG.  2    is a sectional view illustrating a gasket before a sealing assembly is inserted into an exterior housing can in an example of an embodiment. 
         FIG.  3    is a sectional view illustrating a gasket before a sealing assembly is inserted into an exterior housing can in another example of an embodiment. 
         FIG.  4    is a sectional view illustrating a gasket before a sealing assembly is inserted into an exterior housing can in another example of an embodiment. 
         FIG.  5 A  is a diagram for describing an assembly process of a sealing assembly. 
         FIG.  5 B  is a diagram for describing an assembly process of a sealing assembly. 
         FIG.  5 C  is a diagram for describing an assembly process of a sealing assembly. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The shapes, materials, and numbers described below are examples for explanation, and may be appropriately modified with specifications of cylindrical batteries. Hereinafter, similar elements will be represented by the same reference signs in all drawings and described accordingly. 
     A cylindrical battery  10  of an example of an embodiment will be described with reference to  FIG.  1   .  FIG.  1    is a sectional view of the cylindrical battery  10 . 
     As illustrated in  FIG.  1   , the cylindrical battery  10  comprises an electrode assembly  14 , an electrolyte, an exterior housing can  20  that houses the electrode assembly  14  and the electrolyte, and a sealing assembly  30  that seals an opening of the exterior housing can  20 . The electrode assembly  14  includes a positive electrode  11 , a negative electrode  12 , and a separator  13 , and has a wound structure in which the positive electrode  11  and the negative electrode  12  are spirally wound with the separator  13  interposed therebetween. Hereinafter, for convenience of description, the sealing assembly  30  side (an opening side of the exterior housing can  20 ) of the cylindrical battery  10  will be defined as the “upper side”, and a bottom face part  20 A side of the exterior housing can  20  will be defined as the “lower side.” 
     The positive electrode  11  has a positive electrode core, and a positive electrode mixture layer formed on at least one face of the core. For the positive electrode core, there can be used a foil of a metal such as aluminum or an aluminum alloy, which is stable in a potential range of the positive electrode  11 , a film in which such a metal is provided on a surface layer thereof, and the like. The positive electrode mixture layer includes a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride, and is preferably formed on each side of the positive electrode core. For the positive electrode active material, there is used, for example, a lithium-transition metal composite oxide. The positive electrode  11  can be manufactured by applying a positive electrode mixture slurry including a positive electrode active material, a conductive agent, a binder, and the like on the positive electrode core, drying the resulting coating film, and then compressing it to form a positive electrode mixture layer on each side of the core. 
     The negative electrode  12  has a negative electrode core, and a negative electrode mixture layer formed on at least one face of the core. For the negative electrode core, there can be used a foil of a metal such as copper or a copper alloy, which is stable in a potential range of the negative electrode  12 , a film in which such a metal is provided on a surface layer thereof, and the like. The negative electrode mixture layer includes a negative electrode active material and a binder such as styrene-butadiene rubber (SBR), and is preferably formed on each side of the negative electrode core. For the negative electrode active material, there is used, for example, graphite, or a silicon-containing compound. The negative electrode  12  can be manufactured by applying a negative electrode mixture slurry including a negative electrode active material, a binder, and the like on the negative electrode core, drying the resulting coating film, and then compressing it to form a negative electrode mixture layer on each side of the core. 
     For the electrolyte, a non-aqueous electrolyte is used, for example. The non-aqueous electrolyte includes a non-aqueous solvent, and an electrolyte salt dissolved in the non-aqueous solvent. For the non-aqueous solvent, there can be used esters, ethers, nitriles, amides, a mixed solvent containing at least two of those mentioned above, and the like. The non-aqueous solvent may also contain a halogen substitute in which at least a part of hydrogen of these solvents is substituted with a halogen atom such as fluorine. For the electrolyte salt, there is used, for example, a lithium salt such as LiPF 6 . The kind of the electrolyte is not limited to a particular kind of electrolyte, but may also be an aqueous electrolyte. 
     The cylindrical battery  10  has insulating plates  15  and  16  arranged on the upper and lower sides of the electrode assembly  14 , respectively. In the example illustrated in  FIG.  1   , a positive electrode lead  17  connected to the positive electrode  11  extends to the sealing assembly  30  side through a through hole of the insulating plate  15 , and a negative electrode lead  18  connected to the negative electrode  12  extends to the bottom face part  20 A side of the exterior housing can  20  along the outside of the insulating plate  16 . The positive electrode lead  17  is connected, by welding or the like, to a bottom face of an internal terminal plate  31  forming the sealing assembly  30 , and the external terminal plate  33  serves as a positive electrode external terminal. The negative electrode lead  18  is connected, by welding or the like, to an inner face of the bottom face part  20 A of the exterior housing can  20 , and the exterior housing can  20  serves as a negative electrode external terminal. 
     The exterior housing can  20  is a bottomed cylindrical metallic container. A gasket  40  is provided between the exterior housing can  20  and the sealing assembly  30  and the sealing property of the interior of the cylindrical battery  10  is ensured. The exterior housing can  20  has a grooved part  20 C formed by causing a part of a lateral face part  20 B to project inward and configured to support the sealing assembly  30 . The grooved part  20 C is preferably formed into an annular shape along a circumferential direction of the exterior housing can  20 , and supports the sealing assembly  30  on its upper face. The sealing assembly  30  supported on the grooved part  20 C is fixed to an upper part of the exterior housing can  20  by being crimped to an opening end of the exterior housing can  20 . A shoulder part  20 D is formed into an annular shape in the opening end of the exterior housing can  20 . 
     The sealing assembly  30  is a disk-shaped member having a current interrupt mechanism. The sealing assembly  30  has a stacked structure of the internal terminal plate  31 , an insulating plate  32 , and the external terminal plate  33  in this order from the electrode assembly  14  side. The internal terminal plate  31  is a metal plate including an annular part  31 A to which the positive electrode lead  17  is to be connected, and a thin central part  31 B that is disconnected from the annular part  31 A when an internal pressure of the battery exceeds a predetermined threshold. A vent hole  31 C is formed in the annular part  31 A. 
     The external terminal plate  33  is disposed to face the internal terminal plate  31  with the insulating plate  32  interposed therebetween. In the insulating plate  32 , an opening  32 A is formed at a central part in the radial direction, and an vent hole  32 B is formed in a portion overlapping with the vent hole  31 C in the internal terminal plate  31 . The external terminal plate  33  has a vent part  33 A that ruptures when the internal pressure of the cylindrical battery  10  exceeds a predetermined threshold, and the vent part  33 A is connected, by welding or the like, to the central part  31 B of the internal terminal plate  31  with the opening  32 A of the insulating plate  32  interposed therebetween. The insulating plate  32  insulates the internal terminal plate  31  from the external terminal plate  33  around a connection portion therebetween. 
     The vent part  33 A includes a downward projection projecting inward of the battery, and a thin part formed around the downward projection, and is formed at the central part in the radial direction of the external terminal plate  33 . In the cylindrical battery  10 , the internal terminal plate  31  to which the positive electrode lead  17  is connected is electrically connected to the external terminal plate  33 , whereby there is formed a current pathway connecting from the electrode assembly  14  to the external terminal plate  33 . If an abnormality occurs in the cylindrical battery  10 , which causes an increase in the internal pressure of the cylindrical battery, the internal terminal plate  31  breaks, and the central part  31 B is disconnected from the annular part  31 A, whereby the vent part  33 A is deformed to project outward of the battery. Thus, the current pathway is cut off. If the internal pressure of the cylindrical battery  10  further increases, the vent part  33 A ruptures, resulting in formation of a gas venting port. 
     Note that the structure of the sealing assembly is not limited to the structure illustrated in  FIG.  1   . The sealing assembly may have a projected sealing assembly cap covering the vent member. The negative electrode lead may be connected to an inner face of the sealing assembly, and the positive electrode lead may be connected to an inner face of the exterior housing can. In this case, the sealing assembly serves as the negative electrode external terminal, and the exterior housing can serves as the positive electrode external terminal. 
     Next, the gasket  40  will be described with reference to  FIG.  2   .  FIG.  2    is a sectional view illustrating the gasket  40  before the sealing assembly  30  is inserted into an opening of the exterior housing can  20 . 
     The gasket  40  is a seal material interposed between the exterior housing can  20  and the sealing assembly  30 . According to the gasket  40 , a gap between the sealing assembly  30  and the opening of the exterior housing can  20  can be sealed to thereby ensure the sealing properties of the interior of the exterior housing can  20 . For the gasket  40  of the present embodiment, a polyolefin-based resin is used, but the material is not limited thereto. 
     The gasket  40  is formed into a substantially annular shape. The gasket  40  is formed into a substantial L shape when viewed in a cross section in the circumferential direction, before the sealing assembly  30  is crimped to the exterior housing can  20 , and is deformed into a substantial C shape when viewed in a cross section in the circumferential direction, after the sealing assembly  30  is crimped to the exterior housing can  20  (see  FIG.  1   ). The gasket  40  has a projection  40 A projecting outward in the radial direction on the outer peripheral face. 
     An upper part of the gasket  40  extends in an up-and-down direction before the sealing assembly  30  is crimped to the exterior housing can  20 , and is bent and is sandwiched and compressed between the shoulder part  20 D of the exterior housing can  20  and the external terminal plate  33  when the sealing assembly  30  is crimped to the exterior housing can  20 . 
     A lower part of the gasket  40  is disposed between the grooved part  20 C of the exterior housing can  20  and the external terminal plate  33  before the sealing assembly  30  is crimped to the exterior housing can  20 , and is sandwiched and compressed between the grooved part  20 C of the exterior housing can  20  and the external terminal plate  33  when the sealing assembly  30  is crimped to the exterior housing can  20 . 
     The projection  40 A projects outward in the radial direction on the outer peripheral face of the gasket  40 , as described above. The projection  40 A is formed over the entire circumference of the gasket  40 . The projection  40 A comes into abutment with an inner peripheral face of the lateral face part  20 B of the exterior housing can  20 , between the grooved part  20 C and the shoulder part  20 D. Although details will be described later, according to the projection  40 A, the electrolyte adhering to the inner peripheral face of the exterior housing can  20  can be scraped off when the sealing assembly  30  is inserted into the opening of the exterior housing can  20 . Note that the projection  40 A is a portion not compressed when the sealing assembly  30  is crimped to the exterior housing can  20 . 
     An outer diameter (hereinafter, referred to as a gasket maximum diameter) at a tip portion of the projection  40 A in the gasket  40  is preferably set to such a length that the tip portion of the projection  40 A comes into abutment with the inner peripheral face of the lateral face part  20 B of the exterior housing can  20 . The maximum diameter of the projection  40 A is preferably equal to or larger than an inner diameter of the exterior housing can  20 . A length (a length from an outer peripheral face of the gasket  40  to a tip of the projection  40 A (a dimension A in the figure)) in the radial direction of the projection  40 A is preferably 0.05 to 0.15 mm, for example. 
     Accordingly, when the sealing assembly  30  is inserted into the opening of the exterior housing can  20 , the entire circumference of the projection  40 A comes into abutment with the inner peripheral face of the exterior housing can  20  with no gap therebetween, whereby the sealing assembly  30  is inserted into the opening of the exterior housing can  20 . In addition, when the sealing assembly  30  and the gasket  40  are inserted into the opening of the exterior housing can  20 , a center position of the gasket  40  can be easily aligned with a center position of the opening of the exterior housing can  20  in a plan view. This can improve the workability in the manufacturing process of the cylindrical battery  10 . 
     An outer diameter (hereinafter, referred to as a diameter of the gasket) of a portion in which the projection  40 A is not formed in the outer peripheral face of the gasket  40  is preferably smaller than an inner diameter of the exterior housing can  20 . 
     The projection  40 A is formed so that a position in the up-and-down direction of the tip portion is located lower than a position of the upper face of the external terminal plate  33 . Specifically, a difference (a dimension B in the figure) between the position in the up-and-down direction of the tip portion of the projection  40 A and the position in the up-and-down direction of the upper face of the external terminal plate  33  is preferably 1.0 to 1.5 mm. Accordingly, even when the shoulder part  20 D of the exterior housing can  20  presses against the upper face of the external terminal plate  33  at the time of crimping, the projection  40 A can be prevented from being compressed. In addition, the sealing performance of the sealing assembly  30  can be prevented from being deteriorated. 
     The cross-sectional shape in the circumferential direction of the projection  40 A is not limited to a particular shape, but the shape from a root portion to the tip portion of the projection  40 A may have the same width, but is preferably tapered. In the example illustrated in  FIG.  2   , the cross-sectional shape in the circumferential direction of the projection  40 A is a trapezoidal shape. Accordingly, when the sealing assembly  30  and the gasket  40  are inserted into the opening of the exterior housing can  20 , the frictional resistance decreases, whereby the sealing assembly  30  and the gasket  40  can be easily inserted. 
     As illustrated in  FIG.  3   , the cross-sectional shape in the circumferential direction of the projection  40 A may be a triangular shape. In addition, as illustrated in  FIG.  4   , the cross-sectional shape in the circumferential direction of the projection  40 A may be such a triangular shape that an oblique side extends to a lower end of the gasket  40 . 
     The manufacturing process of the cylindrical battery  10  of an example of an embodiment will be described with reference to  FIGS.  5 A,  5 B, and  5 C .  FIGS.  5 A,  5 B , and  5 C each are a diagram for describing an assembly process of the sealing assembly  30 . 
     In the manufacturing process of the cylindrical battery  10 , the electrode assembly  14  is first inserted into the exterior housing can  20 . The sealing assembly  30  is connected to the electrode assembly  14  via the positive electrode lead  17 . Next, the grooved part  20 C for supporting the sealing assembly  30  is formed in the vicinity of the opening of the exterior housing can  20  by spinning the lateral face part  20 B of the exterior housing can  20 . 
     Next, the electrolyte is injected into the exterior housing can  20  until a liquid level position of the electrolyte reaches a position above the grooved part  20 C. The electrolyte gradually saturates the electrode assembly  14 , and the liquid level position of the electrolyte falls from above to below the grooved part  20 C. At this time, the electrolyte may adhere to and remain on the inner peripheral face above the grooved part  20 C of the exterior housing can  20 . 
     Next, as illustrated in  FIG.  5 A , the sealing assembly  30  is inserted into the opening of the exterior housing can  20 . When the above-described gasket maximum diameter of the gasket  40  is equal to or larger than the inner diameter of the exterior housing can  20 , the entire circumference of the projection  40 A comes into abutment with the inner peripheral face of the exterior housing can  20  with no gap therebetween. 
     Next, as illustrated in  FIG.  5 B , the sealing assembly  30  is inserted into the opening of the exterior housing can  20 . At this time, the electrolyte adhering to the inner peripheral face of the exterior housing can  20  is scraped off by the projection  40 A. Even when the gasket maximum diameter is smaller than the inner diameter of the exterior housing can  20 , an effect of scraping off the electrolyte is exhibited by forming the projection  40 A, but the gasket maximum diameter is preferably equal to or larger than the inner diameter of the exterior housing can  20  as in the present embodiment. The electrolyte scraped off by the projection  40 A passes through the grooved part  20 C while flowing along the inner peripheral face of the exterior housing can  20 , and falls down toward the injected electrode. 
     Next, as illustrated in  FIG.  5 C , the opening end of the exterior housing can  20  is crimped, and the sealing assembly  30  is fixed to the opening end of the exterior housing can  20 . At this time, the shoulder part  20 D is formed into an annular shape in the opening end of the exterior housing can  20 . 
     Effects of the cylindrical battery  10  will be described. 
     According to the cylindrical battery  10 , it is possible to reduce the leakage of the electrolyte to the outside of the cylindrical battery  10 . 
     According to the cylindrical battery  10 , the electrolyte adhering to the inner peripheral face of the exterior housing can  20  can be scraped off by the projection  40 A formed in the gasket  40  when the sealing assembly  30  is inserted into the exterior housing can  20 . Accordingly, when the sealing assembly  30  is crimped to the exterior housing can  20 , the electrolyte does not remain between the gasket  40  and the inner peripheral face of the exterior housing can  20 . Therefore, it is possible to reduce the leakage of the electrolyte to the outside of the cylindrical battery  10 . 
     In addition, the electrolyte adhering to the inner peripheral face of the exterior housing can  20  is scraped off by the projection  40 A when the sealing assembly  30  is inserted into the exterior housing can  20 , which makes it possible to reduce variations in electrolyte amount of the cylindrical battery  10 . This can reduce the tolerance of the electrolyte amount of the cylindrical battery  10 . 
     Note that the present disclosure is not limited to the above embodiment and modified example, and various changes and improvements are possible within the matters described in the claims of the present application. 
     REFERENCE SIGNS LIST 
       10  Cylindrical battery,  11  Positive electrode,  12  Negative electrode,  13  Separator,  14  Electrode assembly,  15  Insulating plate,  16  Insulating plate,  17  Positive electrode lead,  18  Negative electrode lead,  20  Exterior housing can,  20 A Bottom face part,  20 C Grooved part,  20 D Shoulder part,  30  Sealing assembly,  31  Internal terminal plate,  31 A Annular part,  31 B Central part,  31 C Vent hole,  32  Insulating plate,  32 A Opening,  32 B Vent hole,  33  External terminal plate,  33 A Vent part,  40  Gasket,  40 A Projection