Secondary battery

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 Art

[0002] A secondary battery is a battery that repeatedly charges and discharges, unlike a primary battery.

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

[0004] For example, a secondary battery includes an electrode assembly that charges and discharges, a case that houses the electrode assembly, a cap plate coupled to an opening of the case, and electrode terminals that draw out the electrode assembly to the outside of 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 coupled to the lower part of a vent hole formed in the case, and the vent plate is formed thinner than the case portion. So, when the internal pressure of the case increases due to overcharging or the like, it is preferentially broken rather than other parts, and by discharging high-temperature gas and pressure to the outside, it plays a role in ensuring the safety of the secondary battery (see Fig. 6a).

[0006] On the other hand, recently, a structure has been proposed in which the vent portion 17 is arranged not at the upper part of the case 15 but at the bottom surface below the case (see Fig. 6b). That is, it is a structure in which the vent portion 17 is arranged on the side opposite to the electrode terminals. A vent hole is formed in the bottom surface of the case, and a vent plate with a notch is hermetically coupled to the vent hole. When high-pressure gas is generated inside the battery cell, the vent plate at the lower part of the case breaks, a pressure difference is generated inside and outside the case, and the gas moves downward in the case due to the pressure difference and is then discharged to the outside through the vent hole.

[0007] On the other hand, 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 sway within the case. Further, it is made of an insulating material, maintains insulation between the electrode assembly and the case, buffers external impacts, and functions to protect the electrode assembly.

[0008] However, as described above, when the vent portion 17 is disposed below the case, the spacer 20 disposed on the bottom surface of the case covers the vent portion 17 and blocks the gas discharge path toward the vent portion, resulting in a restriction on smooth gas discharge. Further, since no other gas flow path is provided in the conventional spacer, it is difficult for gas to be discharged smoothly.

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

[0010] The above information disclosed in the background art of such an invention is only for improving the understanding of the background of the present invention, and thus may also include information that does not constitute the prior art.

Summary of the Invention

Problems to be Solved by the Invention

[0011] The present invention provides a secondary battery having a new form of spacer that has a basic function of fixing an electrode assembly while having a discharge passage for smooth gas discharge in a so-called downward vent structure in which the vent portion is located at the lower part of the case opposite to the electrode terminal.

[0012] However, the technical problems to be solved by the present invention are not limited to the above 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 an embodiment of the present invention for solving the above technical problem includes an electrode assembly, a case for housing the electrode assembly, and a cap plate coupled to an opening on one side of the case. A vent portion is formed to penetrate a surface of the case facing the cap plate. 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 region corresponding to the vent portion on the surface portion of the spacer, and at least one gas discharge hole is formed around the opening. Gas generated inside the case is discharged to the outside through the vent portion after passing through the space portion via the gas discharge hole of the spacer.

[0014] Further, the gas discharge holes are formed to penetrate the surface portion of the spacer and can be arranged in a plurality in the longitudinal and short directions on the surface portion.

[0015] Further, 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 surface portion is separated from a lower bottom surface of the case in which the vent portion is formed by the outer wall portion and the inner wall portion, and the space portion can be formed to be surrounded by the surface portion, the outer wall portion, the inner wall portion, and the lower bottom surface.

[0016] Further, the outer wall portion is continuously formed on long side portions and short side portions of the spacer, and a plurality of exhaust holes are respectively provided in the outer wall portion and the inner wall portion formed on the short side portion, and the inside of the case can be communicated with the space portion of the spacer through the exhaust holes.

[0017] Further, the exhaust holes in the outer wall portion and the exhaust holes in the inner wall portion correspond to each other one-to-one, and the corresponding exhaust holes can be arranged linearly.

[0018] Further, the gas discharge holes arranged in the longitudinal direction can be located above a straight line connecting the exhaust holes in the outer wall portion and the exhaust holes in the inner wall portion.

[0019] Further, the spacer can be arranged at an interval from the inner surface in the longitudinal direction of the case.

Advantages of the Invention

[0020] According to the present invention, while performing the fixing function of the electrode assembly using the conventional spacer, at the same time, through the discharge passage provided in the spacer, gas discharge through the vent portion provided at the lower end of the case can be smoothly performed.

[0021] However, the effects obtained through the present invention are not limited to the above-described 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 Description 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 later, serve to further understand the technical idea of the present invention. Therefore, the present invention should not be construed as being limited only to the matters described in such drawings.

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6a

Figure 6b

Figure 6c

Embodiments for Carrying Out the Invention

[0024] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. The inventor must interpret them in meanings and concepts consistent with the technical idea of the present invention based on the principle that he can appropriately define the concept of the terms in order to explain his own invention in the best way. Therefore, 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 all of the technical ideas of the present invention. It should be understood that there may be various equivalents and modifications that can replace them at the time of this application.

[0025] Also, as used in this specification, "comprise" and / or "including" identify the presence of the recited shape, number, step, operation, member, element, and / or group thereof, and do not exclude the presence or addition of one or more other shapes, numbers, operations, members, elements, and / or groups.

[0026] Furthermore, for the purpose of assisting in the understanding of the present invention, the accompanying drawings are not shown at actual scale, and the dimensions of some components may be exaggerated. Also, the same reference numerals may be assigned to the same components in different embodiments.

[0027] A reference that two comparison targets are "identical" means "substantially identical". Therefore, "substantially identical" can include cases having a deviation regarded as a low level in the industry, for example, a deviation within 5%. Also, the fact that a parameter in a given region is uniform can mean that it is uniform from an average perspective.

[0028] Even if terms such as first, second, etc. are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are only used to distinguish one component from another, and it goes without saying that the first component can be the second component unless there is a contrary description.

[0029] Throughout the specification, unless there is a contrary description, each component may be singular or plural.

[0030] The statement that any configuration is disposed "above (or below)" a component or "above (or below)" a component means not only when any configuration is disposed in contact with the upper (or lower) surface of the component, but also that other configurations may be interposed between the component and any configuration disposed on (or below) the component.

[0031] Furthermore, when a component is described as being "connected", "coupled", or "joined" to another component, it should be understood that the components may be directly connected or joined to each other, but other components may be "interposed" between the components, or each component may be "connected", "coupled", or "joined" to the other component through other components. Also, when a part is electrically coupled to another part, this includes not only the case where they are directly connected, but also the case where other elements are interposed therebetween.

[0032] Throughout the specification, when it is "A and / or B", this means A only, B only, or A and B unless there is a contrary description. That is, "and / or" includes all combinations or any combination of the listed multiple items. When it is "C to D", this means C or more and D or less unless there is a contrary description.

[0033] The terms used in this specification are for the purpose of describing embodiments of the present disclosure and are not intended to limit the present disclosure.

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

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

[0036] The electrode assembly 110 can be formed by winding or laminating a laminate of a first electrode plate, a separator, and a second electrode plate, which are formed in a thin plate shape or a film shape. In the case of a wound laminate, the winding axis of the electrode assembly 110 may be parallel to the longitudinal direction y of the case 130. Further, the electrode assembly 110 may be a stack type rather than a wound type, and the shape of the electrode assembly 110 is not limited in the present invention. Further, the electrode assembly 110 may be a Z-stack electrode assembly 110 in which a positive electrode plate and a negative electrode plate are inserted on both sides of a separator bent in a Z-stack. Further, the long side surfaces of one or more electrode assemblies 110 may be laminated adjacent to each other and housed inside the case 130, and the number of electrode assemblies 110 is not limited in the present invention. The first electrode plate of the electrode assembly 110 can serve as a cathode, and the second electrode plate can serve 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 made 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 plain portion) which is an area where the first electrode active material is not applied. The first electrode tab can serve as a path for the flow of current between the first electrode plate and the first current collecting portion. In some examples, the first electrode tab can be formed by cutting in advance to protrude from one side when manufacturing the first electrode plate, and without further cutting, it can protrude further from one side than the separator.

[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 made of a metal foil such as aluminum or an aluminum alloy, and may include a second electrode tab (or a second plain portion) which is an area where the second electrode active material is not applied. The second electrode tab can serve as a path for the flow of current between the second electrode plate and the second current collecting portion. In some examples, the second electrode tab can be formed by cutting in advance to protrude from the other side when manufacturing the second electrode plate, and without further cutting, it can protrude further from the other side than the separator.

[0039] In some examples, the first electrode tab can be located on the side surface of the left end of the electrode assembly 110, the second electrode tab can be located on the side surface of the right end of the electrode assembly 110, or they can also be located on one surface in the same direction. Here, the left and right sides are for the convenience of explanation based on the secondary battery 100 shown in FIG. 1, and when the secondary battery 100 rotates left - right or up - down, its position can be changed.

[0040] At both end portions of the electrode assembly 110 as described above, the first electrode tab of the first electrode plate and the second electrode tab of the second electrode plate are respectively positioned. In some examples, the electrode assembly 110 can be housed in the case 130 together with the electrolytic solution. Further, the first current collector and the second current collector are respectively welded and connected to the first electrode tab of the first electrode plate and the second electrode tab of the second electrode plate exposed on both sides, and are respectively positioned.

[0041] On the other hand, the case 130 houses the electrode assembly 110. As an example, the case 130 is formed in a substantially rectangular parallelepiped shape so as to set a space for housing the electrode assembly 110 and the electrolytic solution inside, and an opening for connecting the outside and the internal space is formed on one surface 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 thereto, and the case 130 may be configured in various shapes such as circular or pouch type. Further, the case 130 may be made of a metal such as aluminum, an aluminum alloy, or steel plated with nickel, or may be made of a laminate film or plastic constituting a pouch.

[0043] On the other hand, the cap plate 150 is provided at the opening of the case 130 and seals the opening of the case 130. For example, the case 130 and the cap plate 150 can be made of aluminum and welded to each other.

[0044] Further, the cap plate 150 further includes terminal holes H1, H2 and an electrolytic solution injection port (not shown). The electrolytic solution injection port allows the electrolytic solution to be injected into the case 130 after the cap plate 150 is coupled 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 of the electrode assembly 110, respectively. Therefore, the electrode assembly 110 is led out to the outside of the case 130 via the negative electrode terminal 21 and the positive electrode terminal 22.

[0046] On the other hand, the vent portion 170 is formed to penetrate through a surface facing a cap plate coupled to one side opening of the case 130. For example, the cap plate may be coupled to the upper side opening of the case, and the vent portion 170 may be formed on the lower bottom surface of the case facing the cap plate. Through the vent portion 170, high-temperature gas and pressure generated inside the case 130 can be discharged to the outside of the case 130. Specifically, the vent portion 170 includes a vent hole and a vent plate hermetically coupled to the vent hole. An indentation portion may be provided on the formation surface of the vent portion of the case 130 described above, for example, the lower bottom surface, and the vent hole is formed inside the indentation portion. The vent plate seals the vent hole and is provided such that the vent plate is cut open during an event of the cell so that the internal pressure of the secondary battery 100 can be discharged. That is, when the internal pressure reaches the set pressure, the vent plate is cut open to open the vent hole. The vent plate has a notch for inducing the cut.

[0047] On one hand, as shown in FIG. 2, a spacer 200 is disposed between the lower part of the electrode assembly 110 and the vent part, that is, between the electrode assembly and the formation surface of the vent part. When the electrode assembly 110 is housed in the case 130, a clearance is generated between the lower end of the electrode assembly 110 and the formation surface of the vent part of the case 130, that is, the lower bottom surface. By interposing the spacer 200 in the clearance space, the electrode assembly 110 is fixed so as not to sway in the case 130, and it plays a role in suppressing vibration in the height direction. Further, the spacer 200 is formed of a material having electrolyte resistance, and by the characteristics of the material itself or the morphological characteristics, it plays a role in absorbing external shocks. Further, the spacer 200 is 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 the spacer 200 constituting the secondary battery 100 of FIG. 1, and FIG. 4 is a view of the spacer 200 of FIG. 3 seen from various angles. Referring to these figures, the spacer 200 includes a surface part 210 in contact with the electrode assembly 110 and a space part 230 below the surface part 210. Hereinafter, the structure of the spacer 200 will be described more specifically.

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

[0050] On the other hand, at least one gas discharge hole 212 is formed in the periphery of the opening 211 on the surface part 210. The gas discharge holes 212 are formed so as to penetrate the surface part 210 of the spacer 200, and a plurality of them are arranged in the longitudinal direction and the short direction on the surface part 210. For example, in the embodiment shown in FIG. 3, 12 gas discharge holes 212 are provided on both sides of the opening 211, respectively.

[0051] Below such a gas discharge hole 212, a space portion 230 is arranged. The gas generated in the case 130 is configured to be discharged to the outside through the gas discharge hole 212, via the space portion 230, and then through the vent portion 170. Referring to FIGS. 2 to 4, the spacer 200 has an outer wall portion 250 protruding downward from around the surface portion 210. This outer wall portion 250 is continuously formed on the long side portion and the short side portion of the spacer 200. Further, around the opening 211, an inner wall portion 260 protruding downward is similarly provided. By the outer wall portion 250 and the inner wall portion 260, the surface portion 210 is spaced apart from the bottom surface of the case 130 with a preset gap, and this gap is referred to as the space portion 230. That is, the space portion 230 is formed surrounded by the surface portion 210, the outer wall portion 250, the inner wall portion 260, and the lower bottom surface.

[0052] In this way, by providing at least one gas discharge hole 212 so as to penetrate the surface portion 210 in the vertical direction, a gas movement passage can be provided in the vertical direction as indicated by the arrow in FIG. 3.

[0053] On the other hand, according to an embodiment of the present invention, a gas movement passage can also be provided in the horizontal direction as indicated by the arrow in FIG. 3. For this purpose, a plurality of exhaust holes 270 are provided in the spacer 200, and the spacer 200 is arranged at an interval from the inner surface in the longitudinal direction of the case 130.

[0054] Specifically, a plurality of exhaust holes 270 are formed in the outer wall portion 250 formed at the end side portion of the spacer 200. Also, a plurality of exhaust holes 270 are provided in the inner wall portion 260 as well. For example, in the embodiment shown in FIG. 3, three exhaust holes 270 are provided in each of the outer wall portion 250 and the inner wall portion 260. As described above, since the outer wall portion 250 is continuously formed on the long side portion of the spacer 200, 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. Also, although the outer wall portion 250 is continuously formed on the short side portion of the spacer 200, exhaust holes 270 are provided in the short side portion to provide a moving passage for air. At this time, the short side portion of the spacer 200 is disposed at a distance from the inner surface in the longitudinal direction of the case 130. In such a structure, the gas in the case 130 can, as shown in FIG. 2, pass through the exhaust holes 270 provided in the end side portion through the space between the inner surface of the case 130 and the end side portion of the spacer 200, flow into the space portion 230, and be discharged to the outside through the vent portion 170.

[0055] On the other hand, according to an embodiment of the present invention, the exhaust holes 270 in the outer wall portion 250 and the exhaust holes 270 in the inner wall portion 260 correspond to each other one-to-one, and the corresponding exhaust holes 270 can be arranged linearly. By providing the same number of exhaust holes 270 in the inner wall portion 260 and the outer wall portion 250 and arranging the opposing exhaust holes 270 linearly, linear flow of gas is induced. Through this, the gas flowing in through the exhaust holes 270 in the outer wall portion 250 can be discharged to the exhaust holes 270 in the inner wall portion 260 without causing a vortex or causing a minimal vortex in the space portion 230.

[0056] Also, the gas discharge holes 212 arranged longitudinally in the surface portion 210 can be located above the straight line connecting the exhaust holes 270 in the outer wall portion 250 and the exhaust holes 270 in the inner wall portion 260. Through this, the gas flowing in vertically through the gas discharge holes 212 can also merge into the above-described linear flow and be discharged to the exhaust holes 270 in the inner wall portion 260 while causing a minimal vortex.

[0057] According to the present invention, a gas movement passage is provided in a conventional spacer. A gas discharge hole 212 is provided in the plane of the spacer 200 to guide the vertical discharge of gas, and an exhaust hole 270 is provided on the side surface of the spacer 200 to guide the horizontal discharge of gas. Thus, the spacer 200 provided in the secondary battery 100 of the present invention basically provides the advantage that it can perform the function of fixing the electrode assembly 110 while simultaneously performing the function as a gas discharge passage.

[0058] Referring to FIG. 5, the left side shows the experimental result of the gas flow in a secondary battery to which a conventional spacer without a gas discharge passage is applied, and the right side shows the experimental result of the gas flow in a secondary battery provided with the spacer of the present invention. As can be confirmed, since the spacer of the present invention is provided with the exhaust hole 270 on the side surface to enable the horizontal discharge of gas, it can be seen that the gas flow is uniform and active in the horizontal direction of the spacer.

[0059] As described above, even though the present invention is described by way of limited embodiments and drawings, the present invention is not limited thereto, and it goes without saying that various modifications and variations are possible within the equivalent scope of the technical idea of the present invention and the scope of the claims described below by those having ordinary knowledge in the technical field to which the present invention pertains.

Explanation of Reference Numerals

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

Claims

1. An electrode assembly; a case for housing 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; A secondary battery, characterized in that gas generated within the case passes through a space portion via a gas exhaust hole of the spacer, and is then exhausted to the outside via the vent portion.

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

3. 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, 3. The secondary battery of claim 2, wherein the surface portion is separated from a lower bottom surface of the case in which the vent portion is formed by an outer wall portion and an 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 outer wall is continuous with the long and short sides of the spacer; The outer wall and the inner wall formed on the short side portion are each provided with a plurality of exhaust holes, The secondary battery according to claim 3 , wherein the inside of the case communicates with the space of the spacer through the exhaust hole.

5. The secondary battery according to claim 4 , wherein the exhaust holes in the outer wall portion and the exhaust holes in the inner wall portion correspond to each other one-to-one, and the corresponding exhaust holes are arranged in a straight line.

6. The secondary battery according to claim 5 , 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.

7. The secondary battery of claim 3 , wherein the spacer is spaced apart from an inner longitudinal surface of the case.

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