Secondary battery and device including the same

Abstract

A secondary battery according to an embodiment of the present invention includes: a jellyroll-type electrode assembly; a top insulator disposed on the top of the electrode assembly; and a bottom insulator disposed on the bottom of the electrode assembly, wherein at least one of the top insulator and the bottom insulator includes a thermosensitive polymer that expands as temperature increases.

Description

Technical Field

[0001] The present disclosure relates to a secondary battery and a device including the same, and more particularly, to a secondary battery having improved safety against external shock and vibration and a device including the same. Background Art

[0002] As the demand for portable electronic products such as notebooks, cameras and cellular phones is rapidly increasing today, and the development of robots such as electric vehicles, storage batteries, robots, satellites, etc. is actively progressing, a lot of research is being conducted on secondary batteries used as driving power sources.

[0003] The electrode assembly installed in the battery housing is a power generation element having a cathode / separator / anode stacking structure, which can be charged and discharged, and the electrode assembly is divided into a roll type, a stacking type, and a stacking / folding type. The roll type electrode assembly is constructed to have a structure in which a long sheet cathode and a long sheet anode applied with active materials are wound in a state in which a separator is inserted between the cathode and the anode, the stacking type electrode assembly is constructed to have a structure in which a large number of cathodes with a predetermined size and a large number of anodes with a predetermined size are sequentially stacked in a state in which a separator is inserted between the cathode and the anode, and the stacking / folding type electrode assembly is a combination of a roll type electrode assembly and a stacking type electrode assembly. Among them, the roll type electrode assembly has the advantages of easy manufacturing and high energy density per unit weight.

[0004] Such 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 the advantage of having almost no memory effect compared to nickel-based secondary batteries, can be charged and discharged freely, and have a very low self-discharge rate, a high operating voltage, and a high energy density per unit weight.

[0005] According to the shape of the battery case, secondary batteries can be divided into: cylindrical batteries, in which the electrode assembly is installed in a cylindrical metal can; prismatic batteries, in which the electrode assembly is installed in a prismatic metal can; or pouch batteries, in which the electrode assembly is installed in a pouch-shaped case formed by an aluminum laminate. Among them, the advantage of cylindrical batteries is that they have a relatively large capacity and a stable structure. However, cylindrical batteries may be greatly affected by vibrations and shocks in the vertical direction rather than the left and right directions in terms of their structure. When such an electrode assembly is exposed to vibrations and shocks in the vertical direction without any special measures, damage may occur to the electrode assembly or internal components, which leads to performance degradation.

[0006] Therefore, there is a need to develop a secondary battery that can maintain its performance even when exposed to strong vibration or impact. Summary of the invention

[0007] Technical issues

[0008] Embodiments of the present disclosure are designed to solve the above-mentioned problems of previously proposed methods, and an object of the present disclosure is to provide a secondary battery having improved safety even when exposed to external vibration or impact by fixing an internal electrode assembly and a device including the secondary battery.

[0009] However, the problems to be solved by the embodiments of the present disclosure are not limited to the above-mentioned problems, and various extensions can be made within the scope of the technical ideas included in the present disclosure.

[0010] Technical Solution

[0011] A secondary battery according to an embodiment of the present disclosure includes: a jellyroll-type electrode assembly; a top insulator located at the top of the electrode assembly; and a bottom insulator located at the bottom of the electrode assembly, wherein at least one of the top insulator and the bottom insulator includes a thermosensitive polymer that expands according to a temperature increase.

[0012] The thermosensitive polymer may include at least one of pNIPAAm (poly(N-isopropylacrylamide)), pDEAM (poly(N,N-diethylacrylamide)), pNEMAM (poly(N-ethylmethacrylamide)), pMVE (poly(methyl vinyl ether)), pEOVE (poly(2-ethoxyethyl vinyl ether)), pNVCa (poly(N-vinylcaprolactam)), pNVIBAM (poly(N-vinylisobutyramide)) and pNVBAM (poly(N-vinyl-n-butyramide)).

[0013] At least one of the top insulator and the bottom insulator may include an insulating fiber and a coating layer coated on a surface of the insulating fiber, and the coating layer may include the temperature sensitive polymer.

[0014] The insulating fiber may include at least one of polyethylene, polybutylene, polystyrene, polyethylene terephthalate, polypropylene, glass fiber, natural rubber, and synthetic rubber.

[0015] The secondary battery may further include a cathode tab extending upward from the electrode assembly, wherein an opening portion through which the cathode tab passes is formed in the top insulator.

[0016] A gel-type member may be located between an inner wall of the opening and the cathode tab.

[0017] The gel-type member may include the temperature-sensitive polymer.

[0018] An inner wall coating containing a self-healing adhesive may be formed on the inner wall of the opening.

[0019] The self-healing binder may include at least one of a CMC material (ceramic matrix composite), an arginine ester material, and a chitosan material.

[0020] The secondary battery may further include a cylindrical case for storing the electrode assembly.

[0021] The electrode assembly may be fixed between the top insulator and the bottom insulator.

[0022] Beneficial effects

[0023] According to an embodiment of the present disclosure, a secondary battery can be provided, which can fix an electrode assembly even when exposed to external vibration or impact by means of an insulator containing a temperature-sensitive polymer, thereby improving the safety and durability of the secondary battery and a device including the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a cross-sectional perspective view of a secondary battery according to one embodiment of the present disclosure;

[0025] Figure 2 It is shown that the Figure 1 A plan view of a top insulator in a secondary battery;

[0026] Figure 3 is shown along Figure 2 a view of a portion of a cross section taken along line AA' of FIG.

[0027] Figure 4 and Figure 5 It is shown Figure 1 An enlarged partial view of portion "A". DETAILED DESCRIPTION

[0028] Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. The present disclosure can be modified in various different ways and is not limited to the embodiments set forth herein.

[0029] In order to clearly describe the present disclosure, parts irrelevant to the description will be omitted, and the same reference numerals denote the same elements throughout the specification.

[0030] In addition, in the drawings, for the convenience of description, the size and thickness of each element are arbitrarily shown, and the present disclosure is not necessarily limited to those shown in the drawings. In the drawings, for the sake of clarity, the thickness of layers, regions, etc. are exaggerated. In the drawings, for the convenience of description, the thickness of some layers and regions is exaggerated.

[0031] In addition, it should be understood that when an element such as a layer, film, region, or plate is referred to as being "on" or "above" another element, it can be directly on the other element, or there can be intervening elements. Conversely, when an element is referred to as being "directly on" another element, it means that there are no other intervening elements. In addition, the term "on..." or "above..." means being disposed above or below a reference portion, and does not necessarily mean being disposed at the upper end of the reference portion in the opposite direction of gravity.

[0032] Furthermore, throughout the specification, when a part is referred to as “comprising” a certain component, it means that the part may further include other components, without excluding the other components, unless otherwise specified.

[0033] Furthermore, throughout the specification, when referred to as a “plane”, it means when the target portion is viewed from the upper side, and when referred to as a “cross section”, it means when the target portion is viewed from the cross-sectional side cut vertically.

[0034] Figure 1 is a cross-sectional perspective view of a secondary battery 100 according to one embodiment of the present disclosure.

[0035] Reference Figure 1 , the secondary battery 100 according to the present embodiment includes a jellyroll type electrode assembly 120 , a top insulator 160 located at the top of the electrode assembly 120 , and a bottom insulator 170 located at the bottom of the electrode assembly 120 .

[0036] The electrode assembly 120 has a core-wound type structure in which a large number of cathodes 121 and a large number of cathodes 122 are wound with a separator 123 interposed therebetween, and a center pin 150 may be inserted into a central portion thereof.

[0037] At least one of the top insulator 160 and the bottom insulator 170 may include a temperature-sensitive polymer that expands according to a temperature increase. However, it is preferred that both the top insulator 160 and the bottom insulator 170 include a temperature-sensitive polymer for preventing vibration or the like to ensure safety.

[0038] Thermosensitive polymers refer to polymers that react sensitively to temperature in various stimuli and cause rapid physical or chemical changes even by small temperature stimuli.

[0039] Thermosensitive polymers that cause volume changes according to temperature may include at least one of pNIPAAm (poly (N-isopropylacrylamide)), pDEAM (poly (N, N-diethylacrylamide)), pNEMAM (poly (N-ethylmethacrylamide)), pMVE (poly (methyl vinyl ether)), pEOVE (poly (2-ethoxyethyl vinyl ether)), pNVCa (poly (N-vinylcaprolactam)), pNVIBAM (poly (N-vinylisobutyramide)) and pNVBAM (poly (N-vinyl-n-butyramide)).

[0040] Thermosensitive polymers are polymers whose properties change according to external temperature and can cause reversible volume phase change at a specific temperature. That is, the top insulator 160 and the bottom insulator 170 of the present disclosure including the thermosensitive polymer expand as the temperature rises, and then can return to their original state again when the temperature is restored.

[0041] Therefore, when the temperature of the secondary battery 100 increases due to external vibration or impact, the top insulator 160 and the bottom insulator 170 including the thermosensitive polymer may expand to fix the electrode assembly 120 therebetween. In particular, it can be used to generate a buffering effect against vibration in the vertical direction and maintain the performance of the secondary battery 100.

[0042] Meanwhile, when the temperature is about 45° C. or higher, the top insulator 160 and the bottom insulator 170 including the temperature-sensitive polymer expand, thereby protecting the electrode assembly 120 from vibration.

[0043] Figure 2 It is shown that the Figure 1 Hereinafter, the top insulator 160 is described to avoid repeated description, wherein features identical or similar to those of the top insulator 160 described later may also be applied even to the bottom insulator 170. Figure 3 is shown along Figure 2 A view of a portion of the cross section taken along line AA'.

[0044] refer to Figure 2 and Figure 3 The top insulator 160 may include insulating fibers 180, and such insulating fibers 180 may be wound without directionality to form a non-woven fabric-like shape. The insulating fibers 180 may include at least one of polyethylene, polybutylene, polystyrene, polyethylene terephthalate, polypropylene, glass fiber, natural rubber, and synthetic rubber.

[0045] Due to the insulating fibers 180, the top insulator 160 exhibits electrical insulating properties and Figure 1In the embodiment, the occurrence of a short circuit can be prevented by making the electrode assembly 120 contact the bottom 131 of the battery case 130.

[0046] Meanwhile, although not specifically shown, the bottom insulator 170 may also include insulating fibers and exhibit electrical insulating properties, thereby preventing a short circuit from occurring by making the electrode assembly 120 contact the bottom 131 of the battery case 130 .

[0047] A large number of empty spaces may be formed between the insulating fibers 180, and the top insulator 160 may be immersed in a solution containing a thermosensitive polymer, and then washed and dried, so that a coating layer 190 containing a thermosensitive polymer may be formed on the insulating fibers 180. That is, the top insulator 160 may include the insulating fibers 180 wound without directionality and the coating layer 190 coated on the surface of the insulating fibers 180, and the coating layer 190 may include the thermosensitive polymer.

[0048] However, due to a large number of empty spaces between the insulating fibers 180, open holes 300 may be formed in the top insulator 160. The hole 300 in this embodiment refers to a channel-like structure in which some empty spaces between the insulating fibers 180 are interconnected and formed to penetrate the upper and lower surfaces of the top insulator 160.

[0049] like Figure 3 As shown, even if the coating layer 190 is formed on the surface of the insulating fiber 180, it does not block the open holes 300 formed in the top insulator 160 and does not interfere with the flow of gas, so that the air permeability of the top insulator 160 is not deteriorated.

[0050] At the same time, return to reference Figure 1 , the secondary battery 100 may be manufactured by storing the electrode assembly 120 in the battery case 130 , injecting an electrolyte solution into the battery case 130 , and then connecting the cap assembly 140 to the top of the battery case 130 .

[0051] At this time, the battery case 130 may include a crimping portion 132 and a crimping portion 133 .

[0052] The crimping portion 132 refers to a portion in which a portion of the battery case 130 is recessed in a central direction of the electrode assembly 120 , which is used for stable coupling of the cap assembly 140 and preventing movement of the electrode assembly 120 .

[0053] The crimping portion 133 is located above the crimping portion 132 and refers to a portion surrounding the cap assembly 140 , which is used for stable connection of the cap assembly 140 .

[0054] The cap assembly 140 may include: a top cap 141 forming a cathode terminal; a cap plate 142 to which a cathode tap 144 extending upward from the electrode assembly 120 is connected; and a gasket 143 .

[0055] The gasket 143 is installed on the upper inner surfaces of the crimping portion 133 and the crimping portion 132 , thereby increasing the sealing force between the cap assembly 140 and the battery case 130 .

[0056] The battery housing 130 may be a cylindrical housing or a prismatic housing, but is preferably Figure 1 The cylindrical shell shown.

[0057] As described above, the cathode tab 144 may extend upward from the electrode assembly 120. Specifically, the cathode tab 144 may extend from the cathode 121 of the electrode assembly 120.

[0058] The cathode tab 144 is connected to the cap plate 142 so that the top cover 141 may be used as a cathode terminal. An opening portion 161 is formed in the top insulator 160 , and the cathode tab 144 may be connected to the cap plate 142 through the opening portion 161 .

[0059] Figure 4 and Figure 5 are views for explaining a modified embodiment of the present invention, and Figure 1 An enlarged partial view of portion "A".

[0060] First, refer to Figure 4 , the gel-type member 210 may be located between the inner wall of the opening 161 and the cathode terminal 144 .

[0061] As described above, the cathode tab 144 is connected to the cap plate 142 through the opening portion 161. If the cathode tab 144 does not have a separate fixing device, the cathode tab 144 may be short-circuited due to external vibration or impact.

[0062] Therefore, in this embodiment, the gel type member 210 between the inner wall of the opening 161 and the cathode tab 144 may be provided to fill the inner space of the opening 161. Therefore, since the cathode tab 144 may be firmly fixed, the cathode tab 144 may be prevented from being short-circuited due to external vibration or impact.

[0063] The gel-type component 210 may include a thermosensitive polymer, and the thermosensitive polymer may include at least one of pNIPAAm (poly (N-isopropylacrylamide)), pDEAM (poly (N, N-diethylacrylamide)), pNEMAM (poly (N-ethylmethacrylamide)), pMVE (poly (methyl vinyl ether)), pEOVE (poly (2-ethoxyethyl vinyl ether)), pNVCa (poly (N-vinyl caprolactam)), pNVIBAM (poly (N-vinylisobutyramide)) and pNVBAM (poly (N-vinyl-n-butyramide)).

[0064] Therefore, when the temperature of the secondary battery 100 increases due to external vibration or impact, the gel-type member 210 may expand and fill all spaces formed by the opening portion 161 , thereby more firmly fixing the cathode tab 144 .

[0065] Next, refer to Figure 5 , an inner wall coating 220 including a self-healing adhesive is formed on the inner wall of the opening 161 .

[0066] The self-healing binder may include at least one of a CMC material (ceramic matrix composite), an arginine ester material, and a chitosan material. Therefore, the inner wall coating 220 may be endowed with self-healing properties using a reversible covalent bond, so that the inner wall coating 220 may exhibit a temperature-sensitive property.

[0067] In one embodiment of a reversible covalent bond, a hydrophilic polyethylene oxide (PEO) polymer may exhibit temperature-sensitive properties when it changes to a hydrophobic polyphenylene oxide (PPO) at a temperature of about 15 degrees Celsius or higher.

[0068] When the temperature rises, the inner wall coating layer 220 may expand according to the temperature-sensitive property to firmly fix the cathode tap 144 , and may prevent the cathode tap 144 from being short-circuited due to external vibration or impact.

[0069] At the same time, refer to Figure 1 , the center pin 150 generally includes a metal material to impart a predetermined strength and is formed into a cylindrical structure in which a plate is bent into a circular shape. In addition to the self-heating described later, the center pin 150 can also be used as a channel for fixing and supporting the electrode assembly 120 and releasing the gas generated by the internal reaction during charging / discharging and operation.

[0070] At the same time, the electrolyte solution injected into the battery housing 130 can be a non-aqueous electrolyte solution containing a lithium salt, and the non-aqueous electrolyte solution containing a lithium salt is composed of a non-aqueous electrolyte solution and a lithium salt. The non-aqueous electrolyte used herein includes a non-aqueous organic solvent, an organic solid electrolyte, an inorganic solid electrolyte, etc., but is not limited thereto.

[0071] As examples of nonaqueous electrolytes, there can be mentioned aprotic organic solvents such as N-methyl-2-pyrrolidone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl propionate and ethyl propionate.

[0072] Examples of the organic solid electrolyte include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate polymers, polyagitated lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, and polymers containing ion dissociative groups.

[0073] Examples of inorganic solid electrolytes include nitrides, halides and sulfates of lithium (Li), such as Li3N, LiI, Li5NI2, Li3N-LiI-LiOH, LiSiO4, LiSiO4-LiI-LiOH, Li2SiS3, Li4SiO4, Li4SiO4-LiI-LiOH, Li3PO4-Li2S-SiS2.

[0074] Lithium salts are materials that are easily soluble in the above non-aqueous electrolytes. Lithium salts may include, for example, LiCl, LiBr, LiI, LiClO4, LiBF4, LiB 10 Cl 10 , LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, (CF3SO2)2NLi, lithium chloroborane, lithium lower aliphatic carboxylate, lithium tetraphenylborate and imide.

[0075] In addition, in order to improve the charge / discharge characteristics and flame retardancy, the non-aqueous electrolyte may further include, for example, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidinones, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, 2-methoxyethanol, aluminum chloride, etc. In some cases, in order to impart non-flammability, the electrolyte may further include a halogen-containing solvent, such as carbon tetrachloride and ethylene trifluoride. In addition, in order to improve the high temperature retention characteristics, the electrolyte may further include carbon dioxide gas. In addition, fluoroethylene carbonate (FEC), propylene sultone (PRS), etc. may also be included.

[0076] In one specific example, a lithium salt such as LiPF6, LiClO4, LiBF4 and LiN(SO2CF3)2 is added to a mixed solvent of a cyclic carbonate of EC or PC as a high dielectric solvent and a linear carbonate of DEC, DMC or EMC as a low viscosity solvent to prepare a lithium salt-containing non-aqueous electrolyte.

[0077] The secondary battery described above can be applied to various devices. These devices can be applied to vehicle devices such as electric bicycles, electric vehicles, hybrid vehicles, but the present disclosure is not limited thereto and can be applied to various devices that can use battery modules or battery packs including battery modules.

[0078] Although the preferred embodiments of the present disclosure have been described in detail above, the scope of the present disclosure is not limited thereto, and those skilled in the art may also make various modifications and improvements using the basic concepts of the present disclosure defined in the appended claims without departing from the scope of the claims.

[0079] Description of Reference Numerals

[0080] 100: Secondary battery

[0081] 120: Electrode assembly

[0082] 130: Battery housing

[0083] 131: Bottom part

[0084] 132: Crimping part

[0085] 133: Curling part

[0086] 140: Cover assembly

[0087] 150: Center pin

[0088] 160: Top insulator

[0089] 161: Opening

[0090] 170: Bottom insulator

[0091] CROSS-REFERENCE TO RELATED APPLICATIONS

[0092] This application claims the benefit of Korean Patent Application No. 10-2019-0149721 filed in the Korean Intellectual Property Office on November 20, 2019, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A secondary battery, comprising: Core-wound electrode assembly; a top insulator located on top of the electrode assembly; as well as a bottom insulator located at the bottom of the electrode assembly, wherein at least one of the top insulator and the bottom insulator comprises a temperature-sensitive polymer that expands according to a temperature increase and then returns to its original state again when the temperature is restored, and The thermosensitive polymer includes at least one of pDEAM (poly (N, N-diethylacrylamide)), pNEMAM (poly (N-ethylmethacrylamide)), pMVE (poly (methyl vinyl ether)), pEOVE (poly (2-ethoxyethyl vinyl ether)), pNVCa (poly (N-vinyl caprolactam)), pNVIBAM (poly (N-vinyl isobutyramide)) and pNVBAM (poly (N-vinyl-n-butyramide)).

2. The secondary battery according to claim 1, wherein: At least one of the top insulator and the bottom insulator includes an insulating fiber and a coating layer coated on a surface of the insulating fiber, and The coating includes the thermosensitive polymer.

3. The secondary battery according to claim 2, wherein: The insulating fiber includes at least one of polyethylene, polybutylene, polystyrene, polyethylene terephthalate, polypropylene, glass fiber, natural rubber and synthetic rubber.

4. The secondary battery according to claim 1, The secondary battery further includes a cathode tab extending upward from the electrode assembly, in, An opening is formed in the top insulator for the cathode terminal to pass through.

5. The secondary battery according to claim 4, wherein: The gel-type member is located between the inner wall of the opening and the cathode terminal.

6. The secondary battery according to claim 5, wherein: The gel-type member includes the temperature-sensitive polymer.

7. The secondary battery according to claim 4, wherein: forming an inner wall coating containing a self-healing adhesive on the inner wall of the opening, and The self-healing adhesive comprises at least one of a ceramic matrix composite material, an arginine ester material and a chitosan material.

8. The secondary battery according to claim 1, The secondary battery further includes a cylindrical case for storing the electrode assembly.

9. The secondary battery according to claim 1, wherein: The electrode assembly is fixed between the top insulator and the bottom insulator.

10. A device comprising at least one secondary battery according to any one of claims 1 to 9.

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