Secondary battery, its manufacturing method and device including the same

Abstract

A secondary battery according to one embodiment of the present invention includes an electrode assembly; a first battery case that houses the electrode assembly; and a second battery case that covers the first battery case, the second battery case being formed to have a different color from the first battery case.

Description

[Technical Field]

[0001] [Cross-reference to related applications] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0138334, filed on October 18, 2021, and all contents disclosed in the Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a secondary battery and a device including the same, and more specifically to a secondary battery in which expansion of the secondary battery can be easily confirmed and a device including the same. [Background technology]

[0003] In recent years, the demand for portable electronic products such as laptops, video cameras, and mobile phones has increased dramatically. In addition, as the development of electric vehicles, energy storage batteries, robots, and artificial satellites has progressed in earnest, much research has been conducted on secondary batteries used as the driving power sources for these products.

[0004] Depending on the shape of the battery case, secondary batteries are classified into cylindrical batteries in which the electrode assembly is incorporated into a cylindrical metal can, prismatic batteries in which the electrode assembly is incorporated into a prismatic metal can, and pouch batteries in which the electrode assembly is incorporated into a pouch-shaped case made of an aluminum laminate sheet.

[0005] The electrode assembly incorporated into the battery case is a chargeable / dischargeable power generating element consisting of a laminated structure of a positive electrode, a separator, and a negative electrode, and is classified into a jelly roll type, a stack type, and a stack / folded type. The jelly roll type is a long sheet-like positive electrode and negative electrode coated with an active material, with a separator interposed between them, which are then wound up. The stack type is a type in which multiple positive electrodes and negative electrodes of a predetermined size are stacked in sequence with a separator interposed between them. The stack / folded type is a structure that combines the jelly roll type and the stack type. Among these, the jelly roll type electrode assembly has the advantages of being easy to manufacture and having a high energy density per weight.

[0006] Secondary batteries include, for example, nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium secondary batteries, etc. Among them, lithium secondary batteries are widely used in the field of advanced electronic devices because they have advantages over nickel-based secondary batteries, such as almost no memory effect, freedom in charging and discharging, a very low self-discharge rate, a high operating voltage, and a high energy density per unit weight.

[0007] In addition, secondary batteries can experience swelling due to gas generation caused by decomposition of the electrolyte or side reactions within the battery during cycling. By monitoring the degree of gas generation as the cycles progress, it is possible to determine the performance degradation of the secondary battery. However, there was no known method for clearly visually detecting swelling in conventional secondary batteries.

[0008] Therefore, it is necessary to clearly check with the naked eye whether or not the swelling phenomenon occurs, and it is necessary to check the degree of expansion, so a new structure that can solve the above problems is required. Summary of the Invention [Problem to be solved by the invention]

[0009] The problem to be solved by the present invention is to provide a secondary battery in which expansion of the battery can be easily confirmed, and a device including the secondary battery.

[0010] However, the problems to be solved by the embodiments of the present invention are not limited to the above problems, and can be variously expanded within the scope of the technical ideas included in the present invention. [Means for solving the problem]

[0011] A secondary battery according to one embodiment of the present invention includes an electrode assembly; a first battery case that houses the electrode assembly; and a second battery case that covers the first battery case, wherein the second battery case is formed to have a different color from the first battery case.

[0012] The second battery case may have a groove formed therein.

[0013] A plurality of the grooves may be formed on the second battery case.

[0014] The plurality of grooves may be formed on the second battery case so as to be spaced apart from each other.

[0015] When the battery expands, the portion of the second battery case where the groove is formed may burst.

[0016] When the second battery case ruptures, the groove may be connected to the first battery case.

[0017] When the second battery case ruptures, the first battery case may be exposed to the outside.

[0018] The first battery case and the second battery case may be formed of different materials.

[0019] The first battery case may be formed to have greater deformability than the second battery case.

[0020] A method for manufacturing a secondary battery according to another embodiment of the present invention includes the steps of: placing an electrode assembly in a first battery case; and covering the first battery case with the electrode assembly placed therein with a second battery case, wherein the second battery case is formed to have a different color from the first battery case.

[0021] The second battery case may have a groove formed therein.

[0022] A device according to another embodiment of the present invention includes the secondary battery. [Effects of the Invention]

[0023] According to an embodiment of the present invention, the first battery case and the second battery case are formed in different colors, and a groove is formed on the second battery case, so that expansion of the secondary battery can be confirmed with the naked eye.

[0024] In addition, the degree of expansion can be confirmed by the change in size of the groove formed by the rupture of the second case.

[0025] The effects of the present invention are not limited to those mentioned above, and other effects not mentioned above will be clearly understood by those skilled in the art from the claims. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a perspective view showing a pouch-type battery among secondary batteries according to an embodiment of the present invention; [Figure 2] 1 is a perspective view showing a cylindrical battery among secondary batteries according to an embodiment of the present invention; [Figure 3] 1 is a perspective view showing a prismatic battery among secondary batteries according to an embodiment of the present invention; [Figure 4] 1 is a partially exploded perspective view of a pouch-type battery according to an embodiment of the present invention. [Figure 5] 5 is a diagram showing a secondary battery according to an embodiment of the present invention in which the components of FIG. 4 are combined and which includes a second battery case. [Figure 6] FIG. 6 is a diagram showing a cross section taken along the line AA' in FIG. 5. [Figure 7] FIG. 7 is an enlarged view of part C in FIG. 6. [Figure 8] 7A and 7B are diagrams illustrating the secondary battery of FIG. 6 when it expands. [Figure 9] FIG. 9 is an enlarged view of part D in FIG. 8. [Figure 10] 6 is an enlarged view of part B in FIG. 5, showing the state of the first and second battery cases changing due to expansion of the secondary battery. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention may be embodied in various different forms and is not limited to the embodiments set forth herein.

[0028] In order to clearly explain the present invention, parts that are not relevant to the description will be omitted, and the same reference numerals will be used throughout the specification to refer to the same or similar components.

[0029] In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for the convenience of explanation, and the present invention is not necessarily limited to those shown. In the drawings, thicknesses are exaggerated to clearly show multiple layers and regions. In the drawings, thicknesses of some layers and regions are exaggerated for the convenience of explanation.

[0030] Furthermore, when a layer, film, region, plate, or other part is said to be "on" or "above" another part, this includes not only the case where it is "directly above" that part, but also the case where there is another part in between. Conversely, when a part is said to be "directly above" another part, it means that there is no other part in between. Furthermore, being "on" or "above" a reference part means being located above or below the reference part, and does not necessarily mean being located "above" or "above" the opposite direction of gravity.

[0031] Also, throughout the specification, when a part is said to "comprise" a certain element, this means that it may further include other elements, rather than excluding other elements, unless otherwise specified to the contrary.

[0032] Furthermore, throughout the specification, "on a plane" means when the target part is viewed from above, and "on a cross section" means when the target part is cut vertically and viewed from the side.

[0033] Hereinafter, a secondary battery according to an embodiment of the present invention will be described with reference to FIGS.

[0034] Fig. 1 is a view showing a pouch-type battery among secondary batteries according to an embodiment of the present invention. Fig. 2 is a view showing a cylindrical battery among secondary batteries according to an embodiment of the present invention. Fig. 3 is a view showing a prismatic battery among secondary batteries according to an embodiment of the present invention. Fig. 4 is a partially exploded perspective view of an example of a pouch-type battery according to an embodiment of the present invention.

[0035] 1 and 4, the secondary battery 100 according to the present embodiment is a pouch-type secondary battery, and can be manufactured by housing an electrode assembly 105 inside a first battery case 110 and then sealing it.

[0036] The electrode assembly 105 may include a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrodes. The positive and negative electrodes each include a positive electrode tab and a negative electrode tab, and a positive electrode lead 111 connected to the positive electrode tab and a negative electrode lead 112 connected to the negative electrode tab may be exposed to the outside of the first battery case 110. In this case, the positive electrode lead 111 and the negative electrode lead 112 may function as electrode terminals. The positive electrode lead 111 and the negative electrode lead 112 may be collectively referred to as electrode leads 111 and 112.

[0037] The first battery case 110 is made of a laminate sheet and may include a resin layer for thermal sealing and a metal layer for preventing penetration of substances.

[0038] The first battery case 110 may include an upper case 110a and a lower case 110b. Each of the upper case 110a and the lower case 110b may be formed with a separate receiving portion in which the electrode assembly 20 can be seated.

[0039] While the pouch-type battery 100 is shown as a bidirectional battery in which the positive electrode lead 111 and the negative electrode lead 112 protrude in opposite directions, the pouch-type battery 100 of the present invention is not limited to this configuration and includes a unidirectional battery in which the positive electrode lead 111 and the negative electrode lead 112 protrude in the same direction, and a stepped battery in which a step is formed in the electrode assembly housing portion. In particular, referring to Figure 4, a stepped battery in which a step is formed in the electrode assembly housing portion can be seen.

[0040] Referring to FIG. 2, a cylindrical battery 200 includes a first cylindrical battery case 210 made of a metal material, and a second cylindrical battery case 220 that covers the first cylindrical battery case 210.

[0041] In the cylindrical battery 200, the top cap protruding upward can function as a positive electrode terminal 211, and the crimping portion 212 can function as a negative electrode terminal. Therefore, the second battery case 220 can cover the entire top cap that functions as an electrode terminal and the remaining portion except for a part of the crimping portion 212.

[0042] Referring to FIG. 3, a prismatic battery 300 includes a prismatic first battery case 310 made of a metal material, and a prismatic second battery case 320 that covers the prismatic first battery case 310.

[0043] Since the prismatic battery 300 is arranged so that the electrode terminals 311 are exposed on the top surface, the prismatic second battery case 320 is formed on the remaining top surface excluding the portion where the electrode terminals 311 are exposed, as well as on the entire side surface and bottom surface of the prismatic first battery case 310. In other words, the prismatic second battery case 320 can cover the remaining part of the prismatic first battery case 310 excluding the electrode terminals 311.

[0044] The second battery case formed in the secondary battery according to one embodiment of the present invention will be described in detail below with reference to Figures 5 to 10. While the description will focus on a pouch-type battery, modifications of the pouch-type battery to cylindrical and prismatic batteries shown in Figures 2 and 3 are also within the scope of the present invention.

[0045] Figure 5 is a diagram showing a secondary battery according to an embodiment of the present invention, which is formed by combining the components of Figure 4 and includes a second battery case. Figure 6 is a diagram showing a cross section taken along the line A-A' in Figure 5. Figure 7 is an enlarged view of part C in Figure 6. Figure 8 is a diagram showing the secondary battery of Figure 6 when it expands. Figure 9 is an enlarged view of part D in Figure 8. Figure 10 is an enlarged view of part B in Figure 5, showing the state of the first and second battery cases changing due to the expansion of the secondary battery.

[0046] 5 and 6, a secondary battery 100 according to this embodiment includes an electrode assembly 105, a first battery case 110 that houses the electrode assembly 105, and a second battery case 120 that covers the first battery case 110. In this case, the second battery case 120 is formed to have a different color from the first battery case 110.

[0047] Specifically, the first battery case 110 and the second battery case 120 may be formed in various color combinations, and complementary colors may be used for high visibility, or black, yellow, red, etc. Therefore, as will be described later, if the second battery case 120 ruptures due to expansion of the secondary battery 100 and the color of the first battery case 110 is exposed to the outside, it can be easily distinguished with the naked eye. In addition, the degree of expansion of the secondary battery 100 can be predicted based on the degree to which the color of the first battery case 110 is exposed.

[0048] 7, grooves 125 are formed in the second battery case 120. A plurality of grooves 125 are formed on the second battery case 120, and the grooves 125 are formed on the second battery case 120 so as to be spaced apart from each other.

[0049] 5, the distance between the electrode leads 111 and 112 of the secondary battery 100 is defined as the longitudinal direction of the secondary battery 100. Therefore, the grooves 125 are formed on the second battery case 120 of the secondary battery 100 along the longitudinal direction of the secondary battery 100. Furthermore, the grooves 125 may be formed spaced apart from each other along the width direction of the secondary battery 100, which is a direction perpendicular to the longitudinal direction.

[0050] In addition, when forming the groove 125, the groove 125 may be formed on the second battery case 125 so that a portion of the second battery case 120 exists between the groove 125 and the first battery case 110. Therefore, the groove 125 may be formed so that the first battery case 110 is not exposed.

[0051] If gas is generated due to decomposition or side reactions of the electrolyte inside the secondary battery 100, the secondary battery 100 expands, causing swelling, which may result in rupture of the second battery case 120. Specifically, the groove 125 is formed on the second battery case 120, and the portion of the second battery case 120 where the groove 125 is formed is thinner than the other portions. Therefore, if swelling occurs in the secondary battery 100, the portion of the second battery case 120 where the groove 125 is formed may rupture due to the expansion force caused by the swelling.

[0052] 8 and 9, when the second battery case 120 ruptures, the portion of the second battery case 120 between the groove 125 and the first battery case 110 is removed. Here, "removed" means that when the second battery case 120 ruptures, the portion of the second battery case 120 formed between the groove 125 and the first battery case 110 no longer remains. Therefore, when the portion of the second battery case 120 located between the groove 125 and the first battery case 110 is removed, the groove 125 can be connected to the first battery case 110.

[0053] Furthermore, as described above, the groove 125 and the first battery case 110 are connected, so that the first battery case 110 can be exposed to the outside. Therefore, the first battery case 110, which has a different color from the second battery case 120, is exposed to the outside, so that it is possible to visually determine whether or not swelling has occurred in the secondary battery 100. Furthermore, since the area of ​​the first battery case 110 exposed by the groove 125 varies depending on the degree of swelling, the degree of swelling and the degree of battery expansion can be predicted depending on the area.

[0054] Meanwhile, the first battery case 110 and the second battery case 120 may be formed of different materials. Specifically, the second battery case 120 has less deformability against expansion force than the first battery case 110, and may be formed to burst due to being unable to accommodate the expansion of the secondary battery 100. However, even if the second battery case 120 bursts, the first battery case 110 remains intact without bursting, thereby maintaining the performance of the secondary battery 100.

[0055] Therefore, the first battery case 110 can be formed to have greater deformability than the second battery case 120. Also, the material can be selected to have the above-mentioned deformability.

[0056] 10 , as described above, when swelling or expansion occurs in the secondary battery 100, the first battery case 110 may be exposed between the second battery cases 120. At this time, due to the characteristics of cell swelling, the first battery case 110 begins to be exposed from the center of the secondary battery 100. Furthermore, when swelling occurs throughout the entire secondary battery 100, the first battery case 110 may be exposed at multiple locations through multiple grooves 125 formed on the second battery case 120, as shown in FIG. 10 . Depending on the location and degree of exposure of the first battery case 110, the location and degree of swelling of the secondary battery 100 can be confirmed with the naked eye. The extent of swelling and performance degradation of the secondary battery can be predicted based on the area of ​​the exposed first battery case 110.

[0057] A method for manufacturing a secondary battery according to another embodiment of the present invention will be described below. The technical details related to the secondary battery described above are applicable to this embodiment, so duplicated details will be omitted.

[0058] The method for manufacturing a secondary battery according to this embodiment includes the steps of: placing the electrode assembly 105 in a first battery case 110; and covering the first battery case 110 containing the electrode assembly 105 with a second battery case 120. At this time, the second battery case 120 is formed to have a different color from the first battery case 110.

[0059] In addition, a groove 125 may be formed in the second battery case 120, and as described above, when swelling and expansion occur in the secondary battery 100, the second battery case 120 ruptures, exposing the first battery case 110, allowing the expansion to be confirmed with the naked eye.

[0060] In particular, the groove 125 formed on the second battery case 120 is formed along the longitudinal direction of the secondary battery 100 and may be deformed due to the expansion of the secondary battery 100 when a swelling phenomenon occurs.

[0061] In this embodiment, terms indicating directions such as front, back, left, right, up, and down are used, but these terms are used for convenience of explanation and may change depending on the position of the object of interest, the position of the observer, etc.

[0062] The secondary battery according to the present embodiment can be applied to various devices, specifically, transportation means such as electric bicycles, electric cars, and hybrid cars, but is not limited thereto, and can be applied to various devices that can use secondary batteries.

[0063] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to these, and various modifications and improvements made by those skilled in the art that have acquired the basic concept of the present invention defined in the claims also fall within the scope of the present invention. [Explanation of symbols]

[0064] 100 Secondary battery 105 Electrode assembly 110 First battery case 120 Second battery case 125 Groove

Claims

1. electrode assembly; a first battery case that houses the electrode assembly; and A secondary battery including a second battery case covering the first battery case, the second battery case is formed to have a different color from the first battery case; The second battery case has a plurality of grooves formed therein, the grooves are formed along a longitudinal direction of the secondary battery, and are spaced apart from each other along a width direction of the secondary battery, which is a direction perpendicular to the longitudinal direction; and three or more grooves are formed; the second battery case is configured such that a portion of the second battery case where the groove is formed ruptures when the battery expands, A secondary battery, wherein the second battery case ruptures when the battery expands, thereby exposing the first battery case to the outside at a plurality of positions through three or more of the grooves.

2. The secondary battery according to claim 1 , wherein the grooves are formed in a number such that a position where a swelling phenomenon occurs in the secondary battery can be identified.

3. The secondary battery of claim 1 , wherein the groove is connected to the first battery case when the second battery case ruptures.

4. The secondary battery according to claim 1 , wherein the first battery case and the second battery case are formed of different materials.

5. The secondary battery according to claim 4 , wherein the first battery case is formed to have greater deformability than the second battery case.

6. housing the electrode assembly in a first battery case; and 1. A method for manufacturing a secondary battery, comprising: covering the first battery case, in which the electrode assembly is housed, with a second battery case, the second battery case is formed to have a different color from the first battery case; a plurality of grooves are formed in the second battery case; the grooves are formed along a longitudinal direction of the secondary battery, and are spaced apart from each other along a width direction of the secondary battery, which is a direction perpendicular to the longitudinal direction; and three or more grooves are formed; the second battery case is configured such that a portion of the second battery case where the groove is formed ruptures when the battery expands, The method for manufacturing a secondary battery, wherein the second battery case ruptures when the battery expands, thereby exposing the first battery case to the outside at a plurality of positions through three or more of the grooves.

7. A method for manufacturing a secondary battery as described in Claim 6, wherein the groove portions are formed in a number that allows the location where the swelling phenomenon occurs in the secondary battery to be identified.

8. A device comprising the secondary battery according to claim 1.

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