Rechargeable battery

Abstract

A secondary battery comprises an electrode assembly including a first electrode, a second electrode, and a separator located between the first electrode and the second electrode; a case connected to the first electrode to house the electrode assembly and including an opening that exposes the electrode assembly; a cap plate coupled to the case to cover an outer region of the opening and including a through hole that exposes a central region of the opening; a terminal plate insulatedly bonded to the cap plate to cover the through hole and connected to the second electrode; and a terminal plating layer coated on the upper surface of the terminal plate.

Description

Technology Field

[0001] This description relates to secondary batteries. Background Technology

[0002] Generally, a rechargeable battery is a battery that can be charged and discharged.

[0003] Recently, as the demand for wearable devices such as headphones, earphones, smartwatches, and body-attached medical devices using wireless communication such as Bluetooth has increased, the need for ultra-small secondary batteries installed in wearable devices is increasing.

[0004] The electrode terminals located on the outer surface of such ultra-small secondary batteries come into contact with the contact terminals of the wearable device to supply power to the wearable device.

[0005] However, there is a problem in that contact resistance increases between the electrode terminal of the micro secondary battery and the contact terminal of the wearable device due to the natural formation of an oxide film on the surface of the electrode terminal of the micro secondary battery. The problem to be solved

[0006] One embodiment aims to provide a secondary battery in which the formation of an oxide film on the surface of the electrode terminal of the secondary battery is suppressed, and at the same time, the increase in contact resistance between the electrode terminal of the secondary battery and the contact terminal of the device is suppressed. means of solving the problem

[0007] One aspect provides a secondary battery comprising: an electrode assembly including a first electrode, a second electrode, and a separator located between the first electrode and the second electrode; a case connected to the first electrode to house the electrode assembly and including an opening that exposes the electrode assembly; a cap plate coupled to the case to cover an outer region of the opening and including a through hole that exposes a central region of the opening; a terminal plate insulatedly bonded to the cap plate to cover the through hole and connected to the second electrode; and a terminal plating layer coated on the upper surface of the terminal plate, wherein the thickness of the central portion of the terminal plating layer overlapping the through hole is thicker than the thickness of the outer portion of the terminal plating layer overlapping the surface of the terminal plate.

[0008] The surface roughness of the central portion of the terminal plating layer may be smaller than the surface roughness of the outer portion of the terminal plating layer.

[0009] The terminal plating layer may have less ductility compared to the terminal plate.

[0010] The central portion of the terminal plating layer may protrude upward relative to the outer portion of the terminal plating layer.

[0011] The terminal plate comprises aluminum, and the terminal plating layer may comprise nickel.

[0012] The above case and the above cap plate may include stainless steel.

[0013] The terminal plate may include a terminal portion located on the cap plate, and a protrusion connected to the second electrode by penetrating the through hole from the terminal portion.

[0014] The terminal plating layer may be located on the upper surface of the terminal portion.

[0015] The central portion of the terminal plating layer may protrude in the opposite direction to the protrusion.

[0016] The above case and the above cap plate have the same polarity as the first electrode, and the above terminal plate and the above terminal plating layer may have the same polarity as the second electrode.

[0017] It may further include a heat-fusion layer located between the cap plate and the terminal plate, which insulates and bonds the cap plate and the terminal plate.

[0018] The electrode assembly may further include a first electrode tab extending from the first electrode and coupled to the case, and a second electrode tab extending from the second electrode and coupled to the terminal plate. Effects of the invention

[0019] According to one embodiment, a secondary battery is provided in which the formation of an oxide film on the surface of the electrode terminal of the secondary battery is suppressed, and at the same time, the increase in contact resistance between the electrode terminal of the secondary battery and the contact terminal of the device is suppressed. Brief explanation of the drawing

[0020] FIG. 1 is a perspective view showing a secondary battery according to one embodiment. Figure 2 is a cross-sectional view along line II-II of Figure 1. Figure 3 is a cross-sectional view showing part A of Figure 2. Specific details for implementing the invention

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0022] Furthermore, throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0023] Hereinafter, a secondary battery according to one embodiment will be described with reference to FIGS. 1 to 3.

[0024] A secondary battery according to one embodiment is a micro secondary battery and may be a coin cell or a button cell, but is not limited thereto and may be a cylindrical or pin-shaped battery.

[0025] Here, a coin-type battery or a button-type battery refers to a battery in the shape of a thin coin or button, and may refer to a battery in which the ratio of height to diameter (height / diameter) is 1 or less, but is not limited thereto. Since coin-type batteries or button-type batteries are mainly cylindrical, their horizontal cross-section is circular, but is not limited thereto, and shapes in which the horizontal cross-section is elliptical or polygonal may also be included. In this case, the diameter may refer to the maximum distance based on the horizontal direction of the battery, and the height may refer to the maximum distance based on the vertical direction of the battery (the distance from the flat bottom surface to the flat top surface).

[0026] FIG. 1 is a perspective view showing a secondary battery according to one embodiment. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1.

[0027] Referring to FIGS. 1 and 2, a secondary battery (1000) according to one embodiment includes an electrode assembly (100), a case (200), a cap plate (300), a terminal plate (400), a heat-sealed layer (500), and a terminal plating layer (600).

[0028] The electrode assembly (100) is housed in a case (200). The lower part of the electrode assembly (100) faces the bottom of the case (200), and the upper part of the electrode assembly (100) faces a cap plate (300) and a terminal plate (400) that cover the opening (210) of the case (200). The upper and lower parts of the electrode assembly (100) may have a planar shape parallel to each other, but are not limited thereto.

[0029] The electrode assembly (100) includes a first electrode (110), a second electrode (120), a separator (130), a first electrode tab (140), and a second electrode tab (150).

[0030] The first electrode (110) and the second electrode (120) are spaced apart from each other, and a separator (130) containing an insulating material is located between the first electrode (110) and the second electrode (120). The first electrode (110) may be a cathode and the second electrode (120) may be an anode, but is not limited thereto, and the first electrode (110) may be a cathode and the second electrode (120) may be a cathode.

[0031] The first electrode (110) has a band shape extending in one direction and includes an anode coated portion, which is an area where an anode active material layer is applied to a current collector of a metal foil (e.g., Cu foil), and an anode uncoated portion, which is an area where no active material is applied. The anode uncoated portion may be located at one end in the extension direction of the first electrode (110).

[0032] The second electrode (120) has a band shape extending in one direction, spaced apart from the first electrode (110) with a separator (130) in between, and includes a negative coating portion, which is an area where a negative active material layer is applied to a current collector of a metal foil (e.g., Al foil), and a negative non-coating portion, which is an area where no active material is applied. The negative non-coating portion may be located at one end in the extension direction of the second electrode (120).

[0033] The separator (130) extends in one direction between the first electrode (110) and the second electrode (120) to prevent a short circuit between the first electrode (110) and the second electrode (120).

[0034] The first electrode (110), separator (130), and second electrode (120) are sequentially stacked and wound into a jelly roll shape, but are not limited thereto and can be formed in various known shapes. Each of the first electrode (110), second electrode (120), and separator (130) may include various known materials.

[0035] The first electrode tab (140) extends from the first electrode (110) of the electrode assembly (100) to the case (200). The first electrode tab (140) is coupled to the bottom of the case (200) to connect the first electrode (110) and the case (200). The first electrode tab (140) is in contact with the first electrode (110) and the case (200). Due to the first electrode tab (140), the case (200) has the same polarity (e.g., positive) as the first electrode (110).

[0036] The second electrode tab (150) extends from the second electrode (120) of the electrode assembly (100) to the terminal plate (400). The second electrode tab (150) is coupled to a protrusion (420) of the terminal plate (400) to connect the second electrode (120) and the terminal plate (400). The second electrode tab (150) contacts the second electrode (120) and the terminal plate (400). Due to the second electrode tab (150), the terminal plate (400) has the same polarity (e.g., negative) as the second electrode (120).

[0037] Meanwhile, a center pin is positioned in the central part of the electrode assembly (100) that penetrates the center of the electrode assembly (100) in a vertical direction, and this center pin may support the first electrode tab (140) and the second electrode tab (150), but is not limited thereto.

[0038] The case (200) is connected to the first electrode (110) of the electrode assembly (100) and houses the electrode assembly (100). The case (200) includes an opening (210) that exposes the upper part of the electrode assembly (100). The bottom of the case (200) is connected to the first electrode (110) of the electrode assembly (100) by a first electrode tab (140) and has the same polarity as the first electrode (110) (e.g., positive). The case (200) has a cylindrical shape that houses the electrode assembly (100) in the form of a jelly roll, but is not limited thereto and may have various known shapes. The case (200) may house various known electrolytes together with the electrode assembly (100). The outer surface of the case (200) may be a cathode terminal of the secondary battery (1000). At this time, the outer surface of the terminal plate (400) coated with the terminal plating layer (600) may be the anode terminal of the secondary battery (1000). Meanwhile, the outer surface of the case (200) may be coated with a plating layer, but is not limited thereto, and various known coating layers may be coated on the outer surface of the case (200).

[0039] The opening (210) of the case (200) is covered by a cap plate (300) and a terminal plate (400).

[0040] The cap plate (300) is combined with the case (200) to cover the outer area of ​​the opening (210). The cap plate (300) includes a through hole (310) that exposes the central area of ​​the opening (210). The cap plate (300) is directly combined with the side wall of the case (200) forming the opening (210) of the case (200) by a welding process or the like to cover the outer area of ​​the opening (210). The cap plate (300) has a ring shape due to the through hole (310) formed in the center, but is not limited thereto. The cap plate (300) is combined with the case (200) and has the same polarity (e.g., positive) as the first electrode (110). The cap plate (300) includes stainless steel, but is not limited thereto and may include metals such as aluminum, nickel, and copper.

[0041] Meanwhile, a plating layer may be coated on the outer surface of the cap plate (300), but is not limited thereto, and various known coating layers may be coated on the outer surface of the cap plate (300).

[0042] The terminal plate (400) is insulated and bonded to the cap plate (300) to cover the through hole (310) of the cap plate (300). The terminal plate (400) is positioned on the cap plate (300). The terminal plate (400) covers the central area of ​​the opening (210) of the case (200) exposed by the through hole (310) of the cap plate (300). By the terminal plate (400) covering the central area of ​​the opening (210) and the cap plate (300) covering the outer area of ​​the opening (210), the opening (210) of the case (200) is completely covered by the terminal plate (400) and the cap plate (300). The terminal plate (400) is connected to the second electrode tab (150) of the electrode assembly (100) and connected to the second electrode (120) of the electrode assembly (100). The terminal plate (400) has the same polarity as the second electrode (120) (e.g., negative).

[0043] The terminal plate (400) includes a terminal portion (410) and a protrusion (420).

[0044] The terminal portion (410) is located on the cap plate (300) and overlaps with the cap plate (300). The terminal portion (410) has a larger surface area than the protrusion (420). For example, the terminal portion (410) may have a larger diameter than the protrusion (420). The lower surface of the terminal portion (410) is in contact with the heat-fusion layer (500), and the terminal portion (410) is insulatedly bonded to the cap plate (300) by the heat-fusion layer (500).

[0045] The protrusion (420) protrudes from the terminal portion (410) corresponding to the through hole (310) of the cap plate (300) and penetrates the through hole (310). The lower surface of the protrusion (420) contacts the second electrode tab (150). As the protrusion (420) is coupled with the second electrode tab (150), the terminal plate (400) has the same polarity as the second electrode (120).

[0046] The terminal plate (400) may include aluminum, but is not limited thereto, and may include stainless steel or metals such as nickel and copper.

[0047] The heat-fusion layer (500) is located between the cap plate (300) and the terminal portion (410) of the terminal plate (400), and provides insulating bonding between the cap plate (300) and the terminal plate (400). The heat-fusion layer (500) includes an insulating material and provides insulation between the cap plate (300) and the terminal plate (400). The heat-fusion layer (500) is heat-fused between the cap plate (300) and the terminal portion (410) of the terminal plate (400) using heat or a laser beam, etc. The heat-fusion layer (500) may include various known materials that provide insulating bonding between the cap plate (300) and the terminal plate (400). By joining the cap plate (300) and the terminal plate (400) with the heat-fusion layer (500), the opening (210) of the case (200) in which the electrode assembly (100) is housed is completely sealed by the cap plate (300), the terminal plate (400), and the heat-fusion layer (500).

[0048] The terminal plating layer (600) is coated on the upper surface of the terminal portion (410) of the terminal plate (400). Meanwhile, the terminal plating layer (600) is coated only on the upper surface of the terminal portion (410) of the terminal plate (400), but is not limited thereto and can be coated on the entire surface of the terminal plate (400).

[0049] A terminal plate (400) coated with a terminal plating layer (600) forms an anode terminal having the same polarity as the second electrode (120) of the electrode assembly (100) of the secondary battery (1000), but is not limited thereto.

[0050] The terminal plating layer (600) includes a central portion (610) and an outer portion (620), and the central portion (610) of the terminal plating layer (600) protrudes upward relative to the outer portion (620). The terminal plating layer (600) may be plated in the form of a plate on the upper surface of the terminal plate (400) and formed in a shape including the central portion (610) and the outer portion (620) by forging or the like, but is not limited thereto.

[0051] For example, a terminal plating layer (600) can be plated in a plate shape on the upper surface of a plate-shaped terminal plate (400), and the outer portion of the plate-shaped terminal plate (400) on which the plate-shaped terminal plating layer (600) is plated can be forged to simultaneously form a terminal plate (400) including a terminal portion (410) and a protrusion (420) and a terminal plating layer (600) including a central portion (610) and an outer portion (620).

[0052] Figure 3 is a cross-sectional view showing part A of Figure 2.

[0053] Referring to FIG. 3, the central portion (610) of the terminal plating layer (600) corresponds to the through hole (310) of the cap plate (300) and overlaps vertically with the through hole (310), and the outer portion (620) of the terminal plating layer (600) corresponds to the surface of the cap plate (300) and overlaps vertically with the surface of the cap plate (300).

[0054] The first thickness (T1) of the central portion (610) of the terminal plating layer (600) is thicker than the second thickness (T2) of the outer portion (620). The central portion (610) of the terminal plating layer (600) protrudes upward from the surface of the terminal plate (400) relative to the outer portion (620). The central portion (610) of the terminal plating layer (600) protrudes in the opposite direction to the protrusion (420) of the terminal plate (400).

[0055] Since the first thickness (T1) of the central portion (610) of the terminal plating layer (600) is thicker than the second thickness (T2) of the outer portion (620) and the central portion (610) protrudes upward from the surface of the terminal plate (400) compared to the outer portion (620), the central portion (610) of the terminal plating layer (600), which is the electrode terminal of the secondary battery (1000), contacts the contact terminal of the device with a stronger pressure compared to the outer portion (620), and thus the contact area between the central portion (610) of the terminal plating layer (600) and the contact terminal of the device increases, the increase in contact resistance between the central portion (610) of the terminal plating layer (600), which is the electrode terminal of the secondary battery (1000), and the contact terminal of the device is suppressed.

[0056] The surface roughness of the central portion (610) of the terminal plating layer (600) is smaller than the surface roughness of the outer portion (620). The surface of the central portion (610) of the terminal plating layer (600) has a flat surface compared to the surface of the outer portion (620).

[0057] Since the surface roughness of the central portion (610) of the terminal plating layer (600) is smaller than the surface roughness of the outer portion (620), the central portion (610) of the terminal plating layer (600), which is the electrode terminal of the secondary battery (1000), contacts the contact terminal of the device with a wider area than the outer portion (620), and thus the contact area between the central portion (610) of the terminal plating layer (600) and the contact terminal of the device increases, the increase in contact resistance between the central portion (610) of the terminal plating layer (600), which is the electrode terminal of the secondary battery (1000), and the contact terminal of the device is suppressed.

[0058] The terminal plating layer (600) has less ductility compared to the terminal plate (400). The terminal plating layer (600) has greater rigidity compared to the terminal plate (400).

[0059] Since the terminal plating layer (600) has less ductility compared to the terminal plate (400), the deformation of the terminal plating layer (600), which is the electrode terminal of the secondary battery (1000), due to the pressure of contacting the contact terminal of the device is suppressed, and thus the reduction in the contact area between the terminal plating layer (600) and the contact terminal of the device due to the deformation of the terminal plating layer (600) is suppressed, the increase in contact resistance between the terminal plating layer (600), which is the electrode terminal of the secondary battery (1000), and the contact terminal of the device is suppressed.

[0060] The terminal plating layer (600) contains nickel (Ni), and the terminal plate (400) contains aluminum (Al).

[0061] Since the terminal plating layer (600) contains nickel, which has greater corrosion resistance than aluminum included in the terminal plate (400), the formation of an oxide film on the surface of the terminal plating layer (600) that contacts the contact terminal of the device is suppressed, thereby suppressing the increase in contact resistance between the terminal plating layer (600), which is the electrode terminal of the secondary battery (1000), and the contact terminal of the device.

[0062] Thus, according to one embodiment, the secondary battery (1000) has a first thickness (T1) of the central portion (610) of the terminal plating layer (600) that is thicker than the second thickness (T2) of the outer portion (620), and the surface roughness of the central portion (610) is smaller than the surface roughness of the outer portion (620), and the terminal plating layer (600) has less ductility than the terminal plate (400), and the terminal plating layer (600) contains nickel (Ni), so that the central portion (610) of the terminal plating layer (600), which is the electrode terminal of the secondary battery (1000), contacts the contact terminal of the device with strong pressure over a wide area, thereby increasing the contact area between the terminal plating layer (600) and the contact terminal of the device, and at the same time, deformation of the terminal plating layer (600) due to the pressure of contact with the contact terminal of the device is suppressed and the formation of an oxide film on the surface of the terminal plating layer (600) is suppressed, so the secondary The increase in contact resistance between the terminal plating layer (600), which is the electrode terminal of the battery (1000), and the contact terminal of the device is suppressed.

[0063] That is, a secondary battery (1000) is provided in which the formation of an oxide film on the surface of the electrode terminal of the secondary battery (1000) is suppressed, and at the same time, the increase in contact resistance between the electrode terminal of the secondary battery (1000) and the contact terminal of the device is suppressed.

[0064] Although embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention. Explanation of the symbols

[0065] Electrode assembly (100), case (200), cap plate (300), terminal plate (400), heat fusion layer (500), terminal plating layer (600), central portion (610), outer portion (620)

Claims

Claim 1 An electrode assembly comprising a first electrode, a second electrode, and a separator positioned between the first electrode and the second electrode; a case connected to the first electrode to house the electrode assembly and having an opening that exposes the electrode assembly; a cap plate coupled to the case to cover an outer region of the opening and having a through hole that exposes a central region of the opening; a terminal plate insulatedly bonded to the cap plate to cover the through hole and connected to the second electrode; and a terminal plating layer coated on the upper surface of the terminal plate, wherein the thickness of the central portion of the terminal plating layer overlapping the through hole is thicker than the thickness of the outer portion of the terminal plating layer overlapping the surface of the terminal plate. Claim 2 A secondary battery according to claim 1, wherein the surface roughness of the central portion of the terminal plating layer is smaller than the surface roughness of the outer portion of the terminal plating layer. Claim 3 In claim 1, the terminal plating layer has less ductility than the terminal plate in a secondary battery. Claim 4 In claim 1, the central portion of the terminal plating layer protrudes upward relative to the outer portion of the terminal plating layer, in a secondary battery. Claim 5 A secondary battery according to claim 1, wherein the terminal plate comprises aluminum and the terminal plating layer comprises nickel. Claim 6 In paragraph 5, the case and the cap plate comprise a secondary battery made of stainless steel. Claim 7 A secondary battery according to claim 1, wherein the terminal plate comprises: a terminal portion located on the cap plate; and a protrusion connected to the second electrode by penetrating the through hole from the terminal portion. Claim 8 In claim 7, the terminal plating layer is a secondary battery located on the upper surface of the terminal portion. Claim 9 In paragraph 8, the central portion of the terminal plating layer protrudes in the opposite direction to the protrusion of the secondary battery. Claim 10 A secondary battery according to claim 1, wherein the case and the cap plate have the same polarity as the first electrode, and the terminal plate and the terminal plating layer have the same polarity as the second electrode. Claim 11 A secondary battery according to claim 1, further comprising a heat-fusion layer located between the cap plate and the terminal plate and insulatingly bonding the cap plate and the terminal plate. Claim 12 In claim 1, the electrode assembly further comprises: a first electrode tab extending from the first electrode and coupled to the case; and a second electrode tab extending from the second electrode and coupled to the terminal plate.

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