Patent Publication Number: US-2021184184-A1

Title: Rechargeable battery

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0166885, filed in the Korean Intellectual Property Office on Dec. 13, 2019, the entire content of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     Aspects of embodiment of the present invention relate to a rechargeable battery. 
     2. Description of Related Art 
     Different from a primary battery, which not designed to be recharged, a rechargeable battery (also referred to as a secondary battery) is designed to be repeatedly charged and discharged. A small-capacity rechargeable battery may be used in a small portable electronic device, such as a mobile phone, a notebook computer, and a camcorder, and a large-capacity rechargeable battery may be used as, for example, a motor driving power source for a hybrid vehicle and/or an electric vehicle. 
     Some examples of rechargeable batteries include nickel-cadmium (Ni—Cd) batteries, nickel-metal hydride (Ni-MH) batteries, lithium (Li) batteries, and lithium-ion (Li-ion) batteries. Lithium-ion rechargeable batteries have about three times higher operation voltage than nickel-cadmium batteries and nickel-metal hydride batteries, which are frequently used as portable electronic equipment power supplies. In addition, lithium-ion secondary batteries are widely used due to their relatively high energy density per unit weight. 
     As the demand for wearable devices, such as headphones, earphones, smartwatches, and body-mounted medical devices using Bluetooth increases, the need for ultra-small rechargeable batteries with high energy density is increasing. 
     Such ultra-small rechargeable batteries should secure a desired electrical capacity within a limited size, implement an efficient structure while improving effective weight, and improve structural stability. 
     The above information disclosed in this Background section is for enhancement of understanding of the background of the present invention, and therefore, it may contain information that is not prior art. 
     SUMMARY 
     According to embodiments of the present invention, a rechargeable battery having a structure that prevents or substantially reduces the risk of a short circuit between an electrode tab connected to a terminal plate and a cap plate having polarity other than that of the electrode tab is provided. 
     According to an embodiment of the present invention, a rechargeable battery includes: an electrode assembly including a first electrode, a second electrode, a separator between the first electrode and the second electrode, a first electrode tab connected to the first electrode, and a second electrode tab connected to the second electrode, the electrode assembly having opposite first and second ends; a case accommodating the electrode assembly and facing the first end of the electrode assembly, the first electrode tab being connected to the case; and a cap assembly closing and sealing an opening in the case. The cap assembly includes: a cap plate coupled to the case, covering the opening, and facing the second end of the electrode assembly; and a terminal plate coupled to the cap plate. The terminal plate includes: a flange portion coupled to the cap plate and electrically insulated from the cap plate; and a tab connection portion protruding toward the electrode assembly from the flange portion, extending into a terminal opening in the cap plate, and being connected to the second electrode tab. An inner surface of the tab connection portion has a height difference with an inner surface of the cap plate. 
     The inner surface of the tab connection portion may protrude farther toward the second end of the electrode assembly than the inner surface of the cap plate does, and a distal portion of the tab connection portion may be flat. 
     When the second end of the electrode assembly is a reference plane, a first height difference between the inner surface of the cap plate and the second end of the electrode assembly may be greater than a second height difference between the inner surface of the tab connection portion and the second end of the electrode assembly. 
     The inner surface of the tab connection portion facing the second electrode tab may protrude farther toward the second end of the electrode assembly than the inner surface of the cap plate does. 
     When the second end of the electrode assembly is a reference plane, a first height between the inner surface of the cap plate and the second end of the electrode assembly may be greater than a second height between the inner surface of the tab connection portion facing the second electrode tab and the second end of the electrode assembly. 
     The terminal plate may include stainless steel and may be formed by drawing-processing. 
     The flange portion may be parallel with the cap plate, and the tab connection portion may be recessed inward toward the case and may have a flat inner surface. 
     The rechargeable battery may further include an insulation member between the cap plate and the second electrode tab. 
     The insulation member may be plate-shaped and may have an opening therein. The opening in the insulation member may correspond to the terminal opening in the cap plate. 
     The opening in the insulation member may have a smaller diameter than that of the terminal opening. 
     A height is a distance between an outer plane of the case and the terminal plate when the opening in the case is closed and sealed by the cap assembly, a diameter is an exterior circumference of the case, and a height-to-diameter ratio may be less than or equal to 1. 
     The first electrode, the second electrode, and the separator may be spirally wound together. 
     The inner surface of the tab connection portion may have a curved plane shape that convexly protrudes toward the second end of the electrode assembly and may extend beyond the inner surface of the cap plate toward the second end of the electrode assembly. 
     The inner surface of the tab connection portion may have a partially spherical, hemispherical, partially ellipsoidal, or semi-ellipsoidal shape. 
     According to embodiments of the present invention, because an inner surface of a tab connection portion has a height difference with an inner surface of a cap plate, a short circuit between a second electrode tab connected to the tab connection portion of the terminal plate and the cap plate, which is connected to a first electrode tab having a polarity that is different from that of the second electrode tab, may be structurally prevented. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a rechargeable battery according to a first exemplary embodiment of the present invention. 
         FIG. 2  is an exploded perspective view of the rechargeable battery shown in  FIG. 1 . 
         FIG. 3  is a cross-sectional view taken along the line III-III of  FIG. 1 . 
         FIG. 4  is an exploded perspective view of a rechargeable battery according to a second exemplary embodiment of the present invention. 
         FIG. 5  is a cross-sectional view taken along the line V-V of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the present invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Thus, the drawings and description are to be regarded as illustrative in nature and not restrictive. 
     It will be understood that when an element or layer is referred to as being “on,” “connected to,” or “coupled to” another element or layer, it may be directly on, connected, or coupled to the other element or layer or one or more intervening elements or layers may also be present. When an element or layer is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element or layer, there are no intervening elements or layers present. For example, when a first element is described as being “coupled” or “connected” to a second element, the first element may be directly coupled or connected to the second element or the first element may be indirectly coupled or connected to the second element via one or more intervening elements. 
     In the figures, dimensions of the various elements, layers, etc. may be exaggerated for clarity of illustration. The same reference numerals designate the same elements. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Further, the use of “may” when describing embodiments of the present invention relates to “one or more embodiments of the present invention.” Expressions, such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. Also, the term “exemplary” is intended to refer to an example or illustration. As used herein, the terms “use,” “using,” and “used” may be considered synonymous with the terms “utilize,” “utilizing,” and “utilized,” respectively. As used herein, the terms “substantially,” “about,” and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent variations in measured or calculated values that would be recognized by those of ordinary skill in the art. 
     It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of example embodiments. 
     Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” or “over” the other elements or features. Thus, the term “below” may encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly. 
     The terminology used herein is for the purpose of describing particular example embodiments of the present invention and is not intended to be limiting of the described example embodiments of the present invention. As used herein, the singular forms “a” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “includes,” “including,” “comprises,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     According to an exemplary embodiment of the present invention, an ultra-small rechargeable battery is provided. The ultra-small rechargeable battery may be a coin cell type battery or a button cell-type battery. The coin cell-type battery or button cell-type battery is a thin coin or button cell-type battery having a height (H) to diameter (D) ratio (H/D) of 1 or less (see, e.g.,  FIG. 1 ). 
     Because the coin cell-type battery or the button cell-type battery is generally cylindrical, the cross-section thereof in the horizontal direction is circular. The present invention, however, is not limited thereto, and a cross-section of the rechargeable battery in the horizontal direction may have an oval or polygonal shape. According to embodiments of the present invention, the diameter (D) is the maximum diameter (e.g., a maximum exterior diameter) of a case of the rechargeable battery in the horizontal direction, and the height (H) is the maximum distance between the case of the rechargeable battery and an outer plane of the terminal plate. 
     However, the coin cell-type battery or button cell-type battery is an example, and the present invention is not limited thereto. For example, the rechargeable battery may be a cylindrical or pin-type battery. Hereinafter, a coin cell-type battery or a button cell-type battery will be described, in detail, as an example embodiment. 
       FIG. 1  is a perspective view of a rechargeable battery according to a first exemplary embodiment of the present invention,  FIG. 2  is an exploded perspective view of the rechargeable battery shown in  FIG. 1 , and  FIG. 3  is a cross-sectional view taken along the line III-III of  FIG. 1 . 
     Referring to  FIGS. 1-3 , a rechargeable battery  1  according to a first exemplary embodiment includes an electrode assembly  10 , a case  20 , and a cap assembly  30 . The cap assembly  30  includes a cap plate  31  and a terminal plate  32 . The cap plate  31  and the terminal plate  32  are heat-sealed (e.g., heat-sealed together) by a heat-sealing member  34  that is disposed therebetween. 
     The heat-sealing member  34  is a medium for coupling the cap plate  31  and the terminal plate  32  to each other. For example, the heat-sealing member  34  may include (or may be formed of) an electrically-insulating material, such as a polymer, and may be melted by using, for example, a laser to be sealed to both the cap plate  31  and the terminal plate  32 . 
     In the first exemplary embodiment, the terminal plate  32  is coupled to the cap plate  31  by the heat-sealing member  34  such that a stable coupling structure is formed while effectively insulating between the terminal plate  32  and the cap plate  31  without a separate insulating element or configuration. 
     A coin cell-type battery that is manufactured as an ultra-small rechargeable battery has design limitations in terms of space, and accordingly, functionality should be secured while simplifying the structure and manufacturing process. Thus, in the first exemplary embodiment, insulation and coupling between the terminal plate  32  and the cap plate  31  are provided by the heat-sealing member  34 . 
     The electrode assembly  10  includes a first electrode (e.g., a negative electrode)  11  and a second electrode (e.g., a positive electrode)  12 , which are provided at opposite sides of a separator  13 , which is an electrically-insulating member. The electrode assembly  10  is formed by spirally winding the first electrode  11 , the separator  13 , and the second electrode  12 . Thus, the electrode assembly  10  may be formed as a jelly roll-type. 
     The electrode assembly  10  is configured to charge and discharge a current, and a spiral-wound axis of the electrode assembly  10  may be parallel with a height direction of the case  20 . A first end (e.g., a lower end)  101  of the electrode assembly  10  and a second end (e.g., an upper end)  102  of the electrode assembly  10  may be flat and may be parallel with each other. In the first exemplary embodiment, the electrode assembly  10  does not have a center pin, but in other embodiments, a center pin may be provided on (or along) the spiral-wound axis (e.g., may be provided at a center of the electrode assembly  10 ). 
     The case  20  receives (or accommodates) the electrode assembly  10  and faces the first end  101  from among the opposite ends  101 ,  102  of the electrode assembly  10 . For example, the case  20  has a cylindrical shape and accommodates the jelly roll-type electrode assembly  10 , and the cap assembly  30  closes and seals an opening  21  in the cylindrical case  20 . 
     The electrode assembly  10  further includes a first electrode tab  51  connected to the first electrode  11  and a second electrode tab  52  connected to the second electrode  12 . The first electrode  11  and the second electrode  12  are drawn out through (or drawn out to) the first end  101  and the second end  102  of the electrode assembly  10 , respectively. 
     When the electrode assembly  10  is in the case  20 , the first electrode tab  51  is electrically connected to the bottom of the case  20  and the second electrode tab  52  is electrically connected to the terminal plate  32  of the cap assembly  30 . 
     In addition, the cap plate  31  of the cap assembly  30  is coupled to the case  20  while facing the second end  102  from among the opposite ends  101 ,  102  of the electrode assembly  10  and, thus, covers and seals the opening  21  in the case  20 . In this embodiment, the terminal plate  32  is connected to the second electrode tab  52  while being coupled to the cap plate  31 . 
     Hereinafter, the first electrode  11  and the second electrode  12  are described as a negative electrode and a positive electrode, respectively, but the present invention is not limited thereto. For example, the first electrode  11  and the second electrode  12  may be a positive electrode and a negative electrode, respectively. 
     The first electrode (e.g., the negative electrode)  11  has a long band shape (e.g., a strip shape) and includes a current collector (e.g., a metal foil, such as a copper (Cu) foil) having a negative electrode coating portion, which is an area where a negative active material layer is applied, and a negative uncoated region, which is an area where an active material is not applied. The negative uncoated region may be positioned at one end of the negative electrode in the length direction. 
     The second electrode (e.g., the positive electrode)  12  has a long band shape (e.g., a strip shape) and includes a current collector (e.g., a metal foil, such as an aluminum (Al) foil) having a positive electrode coating portion, which is an area where a positive active material layer is applied, and a positive uncoated region, which is an area where an active material is not applied. The positive uncoated region may be positioned at one end of the positive electrode in the length direction. 
     The electrode assembly  10  is inserted into the case  20  through the opening (e.g., a circular-shaped opening)  21  formed in one side of the case  20 , and the case  20  has a space (e.g., has sufficient space or is sufficiently sized) to receive (or accommodate) the electrode assembly  10  and an electrolyte solution therein. For example, the case  20  may have a cylindrical shape having a height (H) that is less than a diameter (D). 
     The terminal plate  32  of the cap assembly  30  has a flange portion  321  and a tab connection portion  322 . The flange portion  321  is attached to the cap plate  31  while being electrically insulated therefrom. The tab connection portion  322  protrudes from the flange portion  321  toward the electrode assembly  10 , extends into (e.g., is inserted into) a terminal opening (e.g., a terminal hole)  311  in the cap plate  31 , and is connected to the second electrode tab  52  of the electrode assembly  10 . 
     In this embodiment, an inner (or bottom) surface  221  of the tab connection portion  322  has a height difference ΔH from an inner (or bottom) surface  312  of the cap plate  31 . The height difference ΔH provides a relatively large safety range that may help prevent a short circuit between the second electrode tab  52 , which has positive polarity, and the cap plate  31 , which has negative polarity, even when the second electrode tab  52  extends (e.g., is stretched) with a length margin between the second end  102  of the electrode assembly  10  and the inner surface  312  of the cap plate  31 . 
     For example, the height difference ΔH may structurally prevent (or substantially prevent) a mutual short circuit between the second electrode tab  52  connected to the terminal plate  32 , which has positive polarity, and the cap plate  31  connected to the first electrode tab  51 , which has negative polarity. 
     For example, the inner surface  221  of the tab connection portion  322  protrudes farther toward the second end  102  of the electrode assembly  10  than the inner surface  312  of the cap plate  31  does and is formed flat (e.g., the inner surface  221  of the tab connection portion  322  is nearer to the second end  102  of the electrode assembly  10  than the inner surface  312  of the cap plate  31  is). When the second end  102  of the electrode assembly  10  is a reference plane, a first height H 1  is formed between the inner surface  312  of the cap plate  31  and the second end  102  of the electrode assembly  10 . 
     A second height H 2  is formed between the flat inner surface  221  of the tab connection portion  322  and the second end  102  of the electrode assembly  10 . Because the second end  102  of the electrode assembly  10  is the reference plane, the second height H 2  is smaller than the first height H 1 . That is, the height difference ΔH between the first height H 1  and the second height H 2  may structurally prevent a mutual short circuit between the second electrode tab  52  and the cap plate  31 . 
     An insulation member  61  is disposed between the cap plate  31  and the second electrode tab  52 . In the first exemplary embodiment, the insulation member  61  has a plate shape that corresponds to the cap plate  31  and may be disposed between (or only between) at least the cap plate  31  and the second electrode tab  52 . 
     The insulation member  61  has an opening (e.g., a through-hole)  611  corresponding to (e.g., aligned or concentric with) the terminal opening  311 . The opening  611  in the insulation member  61  may have a smaller diameter than the concentric terminal opening  311  in the cap plate  31 . Therefore, the second electrode tab  52  may be further prevented from short-circuiting to the cap plate  31  through the terminal opening  311  by the insulation member  61 . 
     For example, the terminal plate  32  may include (or may be formed of) stainless steel by drawing-processing using a plate having a thickness. The terminal plate  32  has the flange portion  321 , which is parallel with the cap plate  31 , and the tab connection portion  322 , which is recessed from an outside of the case  20  toward the inside of the case  20  and has a flat inner surface  221 . The flat inner surface  221  provides improved weldability to the second electrode tab  52 . 
     In the first exemplary embodiment, the entire inner surface  221  of the tab connection portion  322  including the portion facing the second electrode tab  52  is formed in a plane. 
     In the rechargeable battery  1  according to the first exemplary embodiment, the height H is a maximum distance between an outer plane of the case  20  and the terminal plate  32 , and the diameter D is an exterior diameter of the case  20  while the opening  21  in the case  20  is closed and sealed by the cap assembly  30 . In this embodiment, a height H to diameter D ratio (H/D) is less than or equal to about 1 (H/D≤1). For example, the rechargeable battery  1  is a coin cell-type battery or a button cell-type battery, which can be formed in the shape of a thin coin or button. 
     Hereinafter, a second exemplary embodiment of the present invention will be described. Components in the second exemplary embodiment that are the same or substantially similar as those in the first exemplary embodiment may not be described again. Rather, the description of the second exemplary embodiment may focus on the different components therebetween. 
       FIG. 4  is a perspective view of a rechargeable battery according to the second exemplary embodiment of the present invention, and  FIG. 5  is a cross-sectional view taken along the line V-V of  FIG. 4 . Referring to  FIGS. 4 and 5 , the rechargeable battery  2  according to the second exemplary embodiment includes a terminal plate  33  having a flange portion  331  and a tab connection portion  332 . 
     The flange portion  331  is formed parallel to the cap plate  31  and is attached to the cap plate  31  while being electrically insulated therefrom. The tab connection portion  332  convexly protrudes toward the electrode assembly  10  from the flange portion  331 , extends into the terminal opening  311 , and is connected to the second electrode tab  52  of the electrode assembly  10 . 
     The tab connection portion  332  protrudes into the inside of the case  20 , and an inner surface  323  of the tab connection portion  332  has a partially spherical, hemispherical, partially ellipsoidal, or semi-ellipsoidal shape. For example, the tab connection portion  332  may be a curved portion of a partial spherical cylinder, a curved portion of a hemispherical cylinder, a curved portion of a partial ellipsoidal cylinder, or a curved portion of a semi-elliptical cylinder and is connected to the flange portion  331 . 
     In this embodiment, the inner surface  323  of the tab connection portion  332  has a height difference ΔH with the inner surface  312  of the cap plate  31 . The height difference ΔH provides a relatively large safety range that may prevent (or substantially prevent) a short circuit between the second electrode tab  52  and the inner surface  312  of the cap plate  31  even when the second electrode tab  52  is stretched with a length margin between the second end  102  of the electrode assembly  10 . 
     For example, the height difference ΔH may structurally prevent a mutual short circuit between the second electrode tab  52 , which is connected to the terminal plate  32  and has positive polarity, and the cap plate  31 , which is connected to a first electrode tab  51  and has negative polarity. 
     While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the present invention is not limited to the disclosed embodiments. This disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 
     
       
         
           
               
             
               
                   
               
               
                 &lt;Description of Some Reference Symbols&gt; 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 1: rechargeable battery 
                 10: electrode assembly 
               
               
                   
                 11: first electrode 
               
               
                   
                 12: second electrode 
               
               
                   
                 13: separator 
                 20: case 
               
               
                   
                 21: opening 
                 30: cap assembly 
               
               
                   
                 31: cap plate 
                 32, 33: terminal plate 
               
               
                   
                 51: first electrode tab 
                 52: second electrode tab 
               
               
                   
                 61: insulation member 
                 101: first end 
               
               
                   
                 102: second end 
                 221, 323: inner surface 
               
               
                   
                 311: terminal opening 
                 312: inner surface 
               
               
                   
                 321, 331: flange portion 
                 322, 332: tab connection portion 
               
               
                   
                 611: opening 
                 D: diameter 
               
               
                   
                 H: height 
                 H1: first height 
               
               
                   
                 H2: second height 
                 ΔH: height difference