Secondary batteries

Abstract

To provide a secondary battery comprising an exhaust path for smoothly exhausting a gas while concurrently performing a basic function for fixing an electrode assembly with a spacer in a so-called lower type bent structure that is positioned at a lower part of a case where a bent part is opposite to an electrode terminal.SOLUTION: The present invention discloses a secondary battery. On a front surface part of a spacer, an opening is formed in a region corresponding to a vent part, and at least one gas exhaust hole is formed in a circumference of the opening. The gas generated in the case is exhausted to the outside through the vent part after passing a space part via the gas exhaust hole in the spacer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to secondary batteries. [Background technology]

[0002] Unlike primary batteries, secondary batteries are batteries that are repeatedly charged and discharged.

[0003] Small-capacity secondary batteries are used in small portable electronic devices such as mobile phones, laptop computers, and video cameras, while large-capacity secondary batteries can be used as power sources for driving motors in hybrid and electric vehicles.

[0004] For example, a secondary battery includes an electrode assembly for charging and discharging, a case for housing the electrode assembly, a cap plate coupled to an opening of the case, and an electrode terminal for extending the electrode assembly outside the cap plate.

[0005] Here, a vent portion 17 may be formed in the case 15 of the secondary battery. The vent portion has a vent plate attached to the bottom of a vent hole formed in the case. The vent plate is thinner than the case, so when the internal pressure of the case increases due to overcharging, the vent plate breaks first, allowing high-temperature gas and pressure to be released to the outside, thereby ensuring the safety of the secondary battery (see FIG. 6a).

[0006] Recently, a structure has been proposed in which the vent 17 is located on the bottom surface of the case 15 rather than on the top (see Figure 6b). In other words, in this structure, the vent 17 is located on the opposite side from the electrode terminals, with a vent hole formed in the bottom surface of the case and a vent plate with a notch hermetically fitted to the vent hole. When high-pressure gas is generated inside the battery cell, the vent plate at the bottom of the case breaks, creating a pressure difference between the inside and outside of the case. The pressure difference causes the gas to move downwards in the case and then it is released to the outside through the vent hole.

[0007] Meanwhile, a spacer 20 may be interposed between the lower end of the electrode assembly 10 and the bottom surface of the case (see FIGS. 6b and 6c). The spacer 20 serves to fix the jelly roll of the electrode assembly 10 so that it does not shake within the case. Also, the spacer 20 is made of an insulating material to maintain insulation between the electrode assembly and the case and cushion external shocks to protect the electrode assembly.

[0008] However, as mentioned above, when vent 17 is located below the case, spacer 20 located on the bottom of the case covers vent 17, blocking the gas discharge path toward the vent, restricting smooth gas discharge. Furthermore, conventional spacers do not have a separate gas flow path, making it difficult for gas to be discharged smoothly.

[0009] In this case, the internal pressure of the cell may rise suddenly, causing the welded surface of the battery to explode, accelerating the explosion of the surrounding batteries. Therefore, it is necessary to ensure a flow path for smooth gas discharge.

[0010] The above information disclosed in the background of the invention is merely intended to enhance understanding of the background of the invention and may therefore include information that does not constitute prior art. Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention provides a secondary battery having a new type of spacer in a so-called downward vent structure in which the vent portion is located at the bottom of the case opposite the electrode terminals, in which the spacer performs the basic function of fixing the electrode assembly while also providing a discharge passage for smooth discharge of gas.

[0012] However, the technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0013] A secondary battery according to one embodiment of the present invention for solving the above technical problems includes an electrode assembly, a case for accommodating the electrode assembly, and a cap plate coupled to an opening on one side of the case. A vent portion is formed through a surface of the case facing the cap plate. A spacer is disposed inside the case between a lower part of the electrode assembly and the vent portion. The spacer includes a surface portion in contact with the electrode assembly and a space portion below the surface portion. An opening is formed in the surface portion of the spacer in an area corresponding to the vent portion, and at least one gas exhaust hole is formed around the opening. Gas generated inside the case passes through the space portion via the gas exhaust hole of the spacer and is then exhausted to the outside via the vent portion.

[0014] The gas discharge holes may be formed so as to penetrate the surface portion of the spacer, and may be arranged in a plurality of rows in the longitudinal and transverse directions on the surface portion.

[0015] The spacer also includes an outer wall portion protruding downward from around the surface portion and an inner wall portion protruding downward from around the opening, and the surface portion is separated from the lower bottom surface of the case on which a vent portion is formed by the outer wall portion and the inner wall portion, and a space portion can be formed by being surrounded by the surface portion, the outer wall portion, the inner wall portion, and the lower bottom surface.

[0016] In addition, the outer wall portion is formed continuously with the long side and short side portions of the spacer, and the outer wall portion and the inner wall portion formed on the short side are each provided with a plurality of exhaust holes, which can connect the inside of the case to the space portion of the spacer.

[0017] The exhaust holes in the outer wall portion and the exhaust holes in the inner wall portion may correspond one-to-one to each other, and the corresponding exhaust holes may be arranged in a straight line.

[0018] In addition, the gas exhaust holes arranged in the longitudinal direction may be located above a straight line connecting the exhaust hole in the outer wall portion and the exhaust hole in the inner wall portion.

[0019] The spacer may also be spaced from the inner longitudinal surface of the case. [Effects of the Invention]

[0020] According to the present invention, there is an advantage that the conventional spacer can be used to fix the electrode assembly, while at the same time, gas can be smoothly discharged through the exhaust passage provided in the spacer and the vent provided at the bottom of the case.

[0021] However, the effects obtained through the present invention are not limited to the above-mentioned effects, and other technical effects not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Brief explanation of the drawings]

[0022] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited only to the matters depicted in such drawings.

[0023] [Figure 1] 1 is a transparent perspective view of a secondary battery according to an embodiment of the present invention; [Figure 2] FIG. 2 is a cross-sectional view of the secondary battery according to the present invention shown in FIG. [Figure 3] FIG. 2 is a perspective view of a spacer that constitutes the secondary battery of FIG. [Figure 4] 4A to 4C are views of the spacer of FIG. 3 from various angles. [Figure 5] FIG. 10 is a comparative diagram showing experimental results regarding gas flow rate distribution when a spacer according to the prior art and the present invention is applied. [Figure 6a] FIG. 1 is a perspective view of a secondary battery according to the prior art. [Figure 6b] FIG. 1 is a transparent perspective view of still another secondary battery according to the prior art. [Figure 6c]FIG. 6b is a cross-sectional view of the secondary battery according to the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and phrases used in this specification and claims should not be construed as being limited to their ordinary or dictionary meanings, but should be construed in a way that is consistent with the technical concept of the present invention, based on the principle that the inventor can appropriately define the concept of terms in order to best describe his or her invention. Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely some of the most preferred embodiments of the present invention and do not represent the entire technical concept of the present invention, and that various equivalents and modifications that can be substituted for them may exist at the time of this application.

[0025] Also, as used in this specification, "comprise" and / or "comprising" specify the presence of stated shapes, numbers, steps, operations, members, elements, and / or groups thereof, but do not exclude the presence or addition of one or more other shapes, numbers, operations, members, elements, and / or groups.

[0026] Furthermore, to facilitate understanding of the present invention, the accompanying drawings may not be drawn to scale, and the dimensions of some components may be exaggerated. Also, the same reference numerals may be used to refer to the same components in different embodiments.

[0027] A statement that two comparison objects are "identical" means that they are "substantially identical." Therefore, "substantially identical" can include cases where there is a deviation that is considered to be a low level in the art, for example, a deviation within 5%. Furthermore, a parameter being uniform in a given region can mean that the parameter is uniform on average.

[0028] Even if terms such as "first" and "second" are used to describe various components, it should be understood that these components are not limited by these terms. These terms are used only to distinguish one component from another, and it should be understood that a first component can also be a second component unless otherwise specified.

[0029] Throughout the specification, unless specifically stated to the contrary, each element may be singular or plural.

[0030] The phrase "on top (or bottom)" of a component or any structure disposed on the "top (or bottom)" of a component can mean not only that the structure is disposed in contact with the upper surface (or lower surface) of the component, but also that other structures may be interposed between the component and any structure disposed on (or below) the component.

[0031] Furthermore, when a component is described as being "coupled," "coupled," or "connected" to another component, it should be understood that the components may be directly coupled or connected to each other, or that other components may be "interposed" between the components, or that each component may be "coupled," "coupled," or "connected" through other components. Also, when a component is electrically coupled to another component, this includes not only direct coupling, but also coupling via other elements in between.

[0032] Throughout the specification, "A and / or B" means A only, B only, or A and B, unless specifically stated to the contrary. That is, "and / or" includes all or any combination of the listed items. "C through D" means at least C and at most D, unless specifically stated to the contrary.

[0033] The terminology used herein is for the purpose of describing embodiments of the present disclosure and is not intended to limit the present disclosure.

[0034] In an exemplary embodiment of a "cylindrical / prismatic / pouch" battery according to an embodiment of the present disclosure, one of a circular / prismatic / pouch battery is selected and the selected battery is described as having a general structure, and in the case of a generally applicable technology, the general structure of a circular / prismatic / pouch battery is described.

[0035] As shown in FIGS. 1 and 2, a secondary battery 100 according to an embodiment of the present invention may include an electrode assembly 110, a case 130, and a cap plate 150.

[0036] The electrode assembly 110 may be formed by winding or stacking a laminate of a first electrode plate, a separator, and a second electrode plate, each formed in the shape of a thin plate or film. If the electrode assembly 110 is a wound laminate, the winding axis may be parallel to the longitudinal direction y of the case 130. The electrode assembly 110 may also be a stacked type rather than a wound type, and the present invention does not limit the shape of the electrode assembly 110. The electrode assembly 110 may also be a Z-stack electrode assembly 110 in which a positive electrode plate and a negative electrode plate are inserted on either side of a separator folded in a Z-stack. One or more electrode assemblies 110 may be stacked with their long sides adjacent to each other and housed inside the case 130, and the present invention does not limit the number of electrode assemblies 110. The first electrode plate of the electrode assembly 110 may function as a cathode, and the second electrode plate may function as an anode. Of course, the reverse is also possible.

[0037] The first electrode plate is formed by applying a first electrode active material, such as graphite or carbon, to a first electrode current collector plate formed of a metal foil such as copper, a copper alloy, nickel, or a nickel alloy, and may include a first electrode tab (or a first uncoated portion) that is an area where the first electrode active material is not applied. The first electrode tab can be a path for current flow between the first electrode plate and the first current collector. In some examples, the first electrode tab can be formed by cutting the first electrode plate during production so that it protrudes from one side, and can protrude further from the separator on one side without a separate cut.

[0038] The second electrode plate is formed by applying a second electrode active material, such as a transition metal oxide, to a second electrode current collector plate formed of a metal foil, such as aluminum or an aluminum alloy, and may include a second electrode tab (or second uncoated portion), which is an area where the second electrode active material is not applied. The second electrode tab can serve as a path for current flow between the second electrode plate and the second current collector. In some examples, the second electrode tab can be formed by cutting the second electrode plate during production so that it protrudes to the other side, and can protrude further to the other side than the separator without a separate cut.

[0039] In some examples, the first electrode tab may be located on a side surface of the left end of the electrode assembly 110, and the second electrode tab may be located on a side surface of the right end of the electrode assembly 110, or may be located on one surface in the same direction. Here, the left and right sides are used for convenience of explanation based on the secondary battery 100 shown in FIG. 1, and their positions may change when the secondary battery 100 is rotated left and right or up and down.

[0040] A first electrode tab of the first electrode plate and a second electrode tab of the second electrode plate are respectively positioned on both side ends of the electrode assembly 110. In some examples, the electrode assembly 110 may be housed in a case 130 together with an electrolyte. Furthermore, the electrode assembly 110 is positioned such that a first current collector and a second current collector are welded and connected to the first electrode tab of the first electrode plate and the second electrode tab of the second electrode plate, respectively, which are exposed on both sides.

[0041] Meanwhile, the case 130 houses the electrode assembly 110. For example, the case 130 is formed in a substantially rectangular parallelepiped shape to define an internal space for housing the electrode assembly 110 and the electrolyte, and an opening connecting the internal space to the outside is formed on one side of the rectangular parallelepiped. The opening allows the electrode assembly 110 to be inserted into the case 130.

[0042] However, the present invention is not limited to this, and the case 130 may be configured in various shapes such as a circular shape, a pouch shape, etc. Furthermore, the case 130 may be configured from a metal such as aluminum, an aluminum alloy, or nickel-plated steel, or a laminate film or plastic that forms a pouch.

[0043] Meanwhile, the cap plate 150 is provided in the opening of the case 130 to seal the opening of the case 130. For example, the case 130 and the cap plate 150 may be made of aluminum and welded together.

[0044] The cap plate 150 further includes terminal holes H1 and H2 and an electrolyte injection hole (not shown) through which electrolyte can be injected into the case 130 after the cap plate 150 is joined and welded to the case 130.

[0045] The negative electrode terminal 21 and the positive electrode terminal 22 are electrically and mechanically connected to the electrode assembly 110 and are provided in the terminal holes H1 and H2 of the cap plate 150. That is, the negative electrode terminal 21 and the positive electrode terminal 22 are electrically connected to the negative electrode terminal 21 and the positive electrode terminal 22, respectively, of the electrode assembly 110. Therefore, the electrode assembly 110 is drawn out of the case 130 via the negative electrode terminal 21 and the positive electrode terminal 22.

[0046] Meanwhile, the vent portion 170 is formed through a surface of the case 130 facing a cap plate coupled to one side opening. For example, the cap plate may be coupled to the upper opening of the case, and the vent portion 170 may be formed on a lower bottom surface of the case facing the cap plate. High-temperature gas and pressure generated inside the case 130 may be discharged to the outside of the case 130 through the vent portion 170. Specifically, the vent portion 170 includes a vent hole and a vent plate hermetically coupled to the vent hole. A recess may be formed in the surface of the case 130 where the vent portion is formed, for example, the lower bottom surface, and the vent hole is formed inside the recess. The vent plate seals the vent hole and is opened to discharge internal pressure of the secondary battery 100 in the event of a cell malfunction. That is, when the internal pressure reaches a predetermined pressure, the vent plate is opened to open the vent hole. The bent plate has a notch to guide the incision.

[0047] Meanwhile, as shown in FIG. 2 , a spacer 200 is disposed between the bottom of the electrode assembly 110 and the vent, i.e., between the electrode assembly and the surface where the vent is formed. When the electrode assembly 110 is housed in the case 130, there is clearance between the bottom of the electrode assembly 110 and the surface where the vent is formed, i.e., the lower bottom surface of the case 130. The spacer 200 is inserted into the clearance to prevent the electrode assembly 110 from shaking within the case 130 and suppress vibration in the vertical direction. The spacer 200 is made of an electrolyte-resistant material and absorbs external shocks due to the material's inherent properties or morphological properties. The spacer 200 is also made of an insulating material to maintain insulation between the electrode assembly 110 and the case 130.

[0048] Fig. 3 is a perspective view of a spacer 200 constituting the secondary battery 100 of Fig. 1, and Fig. 4 is a view of the spacer 200 of Fig. 3 viewed from various angles. Referring to these figures, the spacer 200 includes a surface portion 210 that contacts the electrode assembly 110 and a space portion 230 below the surface portion 210. The structure of the spacer 200 will be described in more detail below.

[0049] First, the surface portion 210 has a flat plate shape as a portion that comes into contact with the electrode assembly 110. An opening 211 is formed in the surface portion 210 of the spacer 200 at the center in the longitudinal direction of the spacer 200 in a region corresponding to the vent portion 170. By exposing the vent portion 170 to the inside of the case 130 through the opening 211, when an event occurs inside the case 130, gas can directly flow into the vent portion 170 and be discharged.

[0050] Meanwhile, at least one gas exhaust hole 212 is formed in the surface portion 210 around the open opening 211. The gas exhaust holes 212 are formed to penetrate the surface portion 210 of the spacer 200, and a plurality of the gas exhaust holes 212 are arranged in the longitudinal and transverse directions of the surface portion 210. For example, in the embodiment shown in FIG. 3, 12 gas exhaust holes 212 are provided on each side of the open opening 211.

[0051] A space 230 is disposed below the gas exhaust hole 212, and gas generated within the case 130 is configured to be exhausted to the outside via the gas exhaust hole 212, the space 230, and the vent 170. Referring to FIGS. 2 to 4, the spacer 200 has an outer wall 250 that protrudes downward from around the surface 210. The outer wall 250 is formed continuously on the long and short sides of the spacer 200. An inner wall 260 that similarly protrudes downward is provided around the opening 211. The outer wall 250 and the inner wall 260 separate the surface 210 from the bottom surface of the case 130 by a predetermined gap, which is referred to as the space 230. That is, the space 230 is surrounded by the surface 210, the outer wall 250, the inner wall 260, and the lower bottom surface.

[0052] In this way, by providing at least one gas discharge hole 212 that penetrates the surface portion 210 in the vertical direction, a gas transfer path can be provided in the vertical direction as shown by the arrow in FIG.

[0053] On the other hand, according to one embodiment of the present invention, a gas transfer path can be provided in the horizontal direction as shown by the arrows in Figure 3. To this end, a plurality of exhaust holes 270 are provided in the spacer 200, and the spacer 200 is disposed at a distance from the inner surface of the case 130 in the longitudinal direction.

[0054] Specifically, a plurality of exhaust holes 270 are formed in the outer wall portion 250 formed at the end side of the spacer 200. A plurality of exhaust holes 270 are also formed in the inner wall portion 260. For example, in the embodiment shown in FIG. 3, three exhaust holes 270 are formed in each of the outer wall portion 250 and the inner wall portion 260. As described above, the outer wall portion 250 is formed continuously with the long side portion of the spacer 200, so gas does not move between the outer wall portion 250 and the bottom surface of the case 130 in the longitudinal direction of the spacer 200. Furthermore, the outer wall portion 250 is also formed continuously with the short side portion of the spacer 200, but exhaust holes 270 are formed in the short side portion to provide a passage for air movement. In this case, the short side portion of the spacer 200 is disposed at a distance from the inner surface of the case 130 in the longitudinal direction. In such a structure, gas inside the case 130 can flow into the space 230 through the space between the inner surface of the case 130 and the end side of the spacer 200, passing through the exhaust hole 270 provided at the end side, as shown in FIG. 2, and can be discharged to the outside through the vent portion 170.

[0055] Meanwhile, according to one embodiment of the present invention, the exhaust holes 270 of the outer wall portion 250 and the exhaust holes 270 of the inner wall portion 260 may correspond one-to-one to each other, and the corresponding exhaust holes 270 may be arranged in a straight line. By providing the same number of exhaust holes 270 in the inner wall portion 260 and the outer wall portion 250 and arranging opposing exhaust holes 270 in a straight line, a linear flow of gas is induced. As a result, gas flowing in through the exhaust holes 270 of the outer wall portion 250 can be discharged to the exhaust holes 270 of the inner wall portion 260 without generating vortexes or with minimal vortexes within the space portion 230.

[0056] In addition, the gas discharge holes 212 arranged in the longitudinal direction of the surface portion 210 may be located above a straight line connecting the exhaust holes 270 of the outer wall portion 250 and the exhaust holes 270 of the inner wall portion 260. As a result, gas flowing in vertically through the gas discharge holes 212 can also merge with the linear flow and be discharged to the exhaust holes 270 of the inner wall portion 260 while generating minimal vortices.

[0057] According to the present invention, a gas transfer passage is provided in a conventional spacer, but gas exhaust holes 212 are provided on the flat surface of spacer 200 to induce vertical gas discharge, and exhaust holes 270 are provided on the side surface of spacer 200 to induce horizontal gas discharge. As a result, the spacer 200 provided in the secondary battery 100 of the present invention has the advantage that it can basically function as a gas discharge passage while also fixing the electrode assembly 110.

[0058] 5, the left side shows the experimental results of gas flow in a secondary battery using a conventional spacer without a gas exhaust passage, and the right side shows the experimental results of gas flow in a secondary battery using the spacer of the present invention. As can be seen, the spacer of the present invention has exhaust holes 270 on the side, allowing gas to be exhausted horizontally, resulting in uniform and active gas flow in the horizontal direction of the spacer.

[0059] Although the present invention has been described above using limited examples and drawings, it goes without saying that the present invention is not limited thereto, and that various modifications and variations can be made by a person having ordinary skill in the art to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims set forth below. [Explanation of symbols]

[0060] 21: Negative terminal 22: Positive terminal 100: Secondary battery 10, 110: Electrode assembly 15, 130: Case 150: Cap plate 17, 170: Vent section 20, 200: Spacer 210: Surface part 211: Open mouth 212: Gas exhaust hole 230: Spatial part 250:Outer wall 260:Inner wall 270: Exhaust vent H1, H2: Terminal holes

Claims

1. an electrode assembly; a case for accommodating the electrode assembly; a cap plate coupled to an opening on one side of the case, a vent portion is formed through a surface of the case facing the cap plate, and a spacer is disposed inside the case between a lower portion of the electrode assembly and the vent portion; the spacer includes a surface portion in contact with the electrode assembly and a space portion below the surface portion; an opening is formed in a surface portion of the spacer in a region corresponding to the vent portion, and at least one gas exhaust hole is formed around the opening; the spacer includes an outer wall portion protruding downward from around the surface portion and an inner wall portion protruding downward from around the opening, the outer wall is formed continuously with the long and short sides of the spacer; the outer wall portion and the inner wall portion formed on the short side portion are each provided with a plurality of exhaust holes that are aligned in a side direction of the short side portion, the exhaust hole connects the interior of the case to the space of the spacer, The secondary battery, wherein the exhaust holes of the outer wall portion and the exhaust holes of the inner wall portion correspond to each other one-to-one, and the corresponding exhaust holes are arranged in a straight line.

2. The secondary battery according to claim 1 , wherein the gas discharge holes are formed so as to penetrate the surface portion of the spacer, and a plurality of the gas discharge holes are arranged in the longitudinal and transverse directions on the surface portion.

3. 3. The secondary battery of claim 2, wherein the surface portion is separated from the lower bottom surface of the case on which the vent portion is formed by the outer wall portion and the inner wall portion, and the space portion is formed by being surrounded by the surface portion, the outer wall portion, the inner wall portion, and the lower bottom surface.

4. The secondary battery according to claim 1 , wherein the gas exhaust holes arranged in the longitudinal direction are located above a straight line connecting the exhaust hole in the outer wall portion and the exhaust hole in the inner wall portion.

5. The secondary battery according to claim 3 , wherein the spacer is spaced apart from an inner surface of the case in the longitudinal direction.

6. The secondary battery according to claim 1 , wherein the gas generated in the case passes through the space portion via the gas exhaust hole of the spacer and is then exhausted to the outside via the vent portion.

7. The secondary battery according to claim 1 , wherein the vent portion is exposed through the opening.

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