KR20190072203A - Cylindrical Battery Having Carbon Material - Google Patents

Abstract

The present invention relates to a cylindrical battery in which an electrode assembly is accommodated together with an electrolyte. The battery comprises: a batter case accommodating the electrode assembly and made of a metal material; a cap assembly positioned at an open upper end of the battery case; an insulation member positioned at an upper portion and/or a lower portion of the electrode assembly to ensure insulation of the electrode assembly; and a gas removal layer formed on at least a portion of the inside of the battery case and including a carbon material. The gas generated during the use of the battery is removed to prevent deterioration and explosion of the battery.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a cylindrical battery including a carbon material,

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a cylindrical battery including a carbon material, and more particularly, to a cylindrical battery in which a gas removing layer containing a carbon material is formed inside a battery case.

As technology development and demand for mobile devices increase, rechargeable secondary batteries are widely used as energy sources for various mobile devices. In addition, the secondary battery is attracting attention as an energy source for electric vehicles, hybrid electric vehicles, and the like, which is proposed as a solution for air pollution in existing gasoline vehicles and diesel vehicles using fossil fuels.

2. Description of the Related Art Generally, a secondary battery includes a cylindrical battery and a prismatic battery in which an electrode assembly is embedded in a cylindrical or rectangular metal can according to the shape of a battery case, and a pouch type battery in which an electrode assembly is embedded in a pouch- .

The electrode assembly embedded in the battery case includes a positive electrode, a negative electrode, and a separation membrane structure interposed between the positive electrode and the negative electrode. The power generation device includes a separator interposed between a positive electrode and a negative electrode coated with an active material, A jelly-roll type, and a plurality of positive electrodes and a negative electrode of a predetermined size, which are stacked in a stacked state with a separator interposed therebetween. Among them, the jelly-roll type electrode assembly is widely used in applications requiring a high-capacity secondary battery because it is easy to manufacture and has a high energy density per weight.

In the case where the cylindrical battery is exposed to an unhealthy temperature range due to an abnormal condition such as overcharging or short circuit, heat inside the battery can not be discharged, Causing an explosion.

This is because the hydrogen gas generated by the reaction of the electrolyte or the like, which is the internal material of the battery, accelerates the high temperature phenomenon of the internal material of the battery, which generates heat, and strengthens the ignition or explosive force of the battery.

In order to solve such a problem, Patent Document 1 discloses a closed type battery having a storage member containing a hydrogen storage alloy inside a battery case, but the hydrogen storage alloy causes a side reaction in accordance with a change in potential difference inside the battery, There is a problem in that the performance of the display device may be deteriorated.

Patent Document 2 discloses a structure in which a gas adsorption layer is formed in addition to a sealed portion on the inner surface of an electrode group housing portion as a laminate cell having a casing made of a film. However, since the gas adsorbing layer contains silica gel or transition metal oxide, there is a problem that the mass per unit volume increases.

Therefore, there is a high need for a technique capable of mitigating the generation of hydrogen gas or the like generated by the reaction in the battery while minimizing the mass increase of the battery itself as well as not causing side reactions with the electrolyte solution.

Japanese Laid-Open Patent Publication No. 2016-095928 Japanese Laid-Open Patent Publication No. 2012-059489

It is an object of the present invention to provide a cylindrical battery with improved safety that can prevent ignition or explosion of a battery by absorbing and removing hydrogen gas generated in a cylindrical battery.

According to an aspect of the present invention, there is provided a cylindrical battery comprising:

A cylindrical battery in which an electrode assembly is housed together with an electrolyte,

A battery case accommodating the electrode assembly and made of a metal material;

A cap assembly positioned at an open upper end of the battery case;

An insulation member positioned at an upper portion and / or a lower portion of the electrode assembly to ensure insulation of the electrode assembly; And

And a gas removing layer formed on at least a part of the inside of the battery case and including a carbon material.

As described above, the present invention includes a gas removing layer including a carbon material in at least part of the inside of a battery case for housing an electrode assembly and an insulating member housed inside the cylindrical battery, It is possible to adsorb or remove a gas such as hydrogen gas generated inside. In addition, since the gas removing layer includes a carbon material having excellent gas removing ability, it is possible to remove gas quickly as compared with the case of using other gas removing materials.

That is, it is possible to rapidly remove the gas generated during the abnormal use process due to normal use process of the battery, overcharge, external impact or short circuit, etc., and it is possible to prevent the deterioration of the battery due to the gas, , The risk of ignition or explosion of the battery can be eliminated.

In one specific example, the degassing layer may be in the form of a film, in the form of a tape using an adhesive, or may be formed by spraying.

Specifically, a film-type gas removing layer containing a carbon material may be disposed on the inner surface of the battery case, or a sheet having an adhesive layer formed on one surface thereof may be disposed in the form of a tape inside the battery case and / Element. Alternatively, the powder particles containing the carbon material may be added to the inside of the battery case by a spraying method by spraying.

For example, the gas removing layer may be formed on any one portion selected from the group consisting of the inner side wall of the battery case, the electrode tab attached to the electrode assembly, the lower surface of the cap assembly, and the surface of the insulating member In order to quickly remove the gas inside the battery, it is preferable to form at least two portions of the portions at the same time.

The gas-removing layer may include a carbon material having excellent gas adsorption capability, and may be composed of a single-walled carbon nanotube (SWNT) or a carbon material having a three-dimensional network structure capable of absorbing a large amount of gas .

The single-walled carbon nanotubes (SWNTs) have a structure of a tube-like structure in which six hexagonal carbon shapes are connected to each other to form a tubular shape. The diameter of the single-walled carbon nanotubes is nanometer- It has high thermal conductivity and 100 times better strength than steel.

The carbon material of the three-dimensional network structure may be a two-dimensional network structure having a specific polygon or a three-dimensional network structure sharing a vertex or a corner face of a specific polyhedron.

Accordingly, in the case of the single-walled carbon nanotube structure, a large amount of gas can be trapped in the hexagonal carbon rings, the tubular tube-shaped interior, and the spatial gaps formed in the three-dimensional network structure.

On the other hand, the single-walled carbon nanotube may have a structure coated with titanium (Ti) or another transition metal. In particular, the gas adsorption capability is further improved by coating with titanium.

In one specific example, the battery case may be a structure that is combined with the negative electrode tab of the electrode assembly to electrically form the negative electrode.

In other words, when considering that a carbonaceous material is generally used as a negative electrode material when a gas removing layer containing a carbon material is formed in a battery case, Unlike the present invention, the use of a gas-removing layer made of an alloy material of a metal can prevent the problem of deteriorating the performance of the battery due to side reactions caused by dislocations.

In one specific example, it is preferable that the gas removing layer is formed to be wide in order to suppress deterioration of the battery. For example, the gas removing layer may further include a structure for covering a part of the outer surface of the electrode assembly.

In the case where the gas-removing layer is further included in the outer surface of the electrode assembly as described above, the gas-removing layer may be formed on the fixing member for preventing the electrode assembly from being unwound when the electrode assembly is of the winding type. Or a structure in which a gas removing layer is formed to surround the entire outer surface of the electrode assembly.

Conventionally, when a hydrogen storage alloy composed of a metal alloy is applied to the inside of a battery for the purpose of degassing, there is a problem that a side reaction product that deteriorates the performance of a battery as a result of a chemical reaction with an internal substance of the battery with an electrolyte or the like is formed It is preferable that the gas-removing layer is made of a material which does not generate a chemical reaction with the electrolytic solution.

The cylindrical battery according to the present invention may be a lithium secondary battery having a structure in which a nonaqueous electrolyte solution containing a lithium salt is impregnated in an electrode assembly having a separator interposed between an anode and a cathode.

The positive electrode is prepared, for example, by applying a positive electrode mixture containing a positive electrode active material on a positive electrode collector and then drying the positive electrode mixture. Optionally, a binder, a conductive material, a filler, .

The cathode current collector generally has a thickness of 3 to 500 mu m. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery, and may be formed of a material such as stainless steel, aluminum, nickel, titanium, sintered carbon, or a surface of aluminum or stainless steel Treated with carbon, nickel, titanium, silver or the like may be used. The positive electrode current collector may have fine unevenness formed on the surface thereof to increase the adhesive force of the positive electrode active material as in the case of the negative electrode current collector. Alternatively, the positive electrode current collector may have various properties such as a film, sheet, foil, net, porous body, Form is possible.

The cathode active material is a material capable of causing an electrochemical reaction. Examples of the lithium transition metal oxide include lithium cobalt oxide (LiCoO ₂ ) containing two or more transition metals and substituted with one or more transition metals, lithium Layered compounds such as nickel oxide (LiNiO ₂ ); Lithium manganese oxide substituted with one or more transition metals; Formula _{LiNi 1-y M y O 2} ( where, M = Co, Mn, Al , Cu, Fe, Mg, B, Cr, Zn or Ga and Lim, 0.01≤y≤0.7 include one or more elements of the element) A lithium nickel-based oxide represented by the following formula: _{Li 1 + z Ni 1/3 Co 1/3} Mn 1/3 O 2, Li 1 + z Ni 0.4 Mn 0.4 Co 0.2 O 2 , such as _{Li 1 + z Ni b Mn c} Co 1- (b + c + d _{) M d O (2-e} ) A e ( where, -0.5≤z≤0.5, 0.1≤b≤0.8, 0.1≤c≤0.8, 0≤d≤0.2 , 0≤e≤0.2, b + c + d <1, M = Al, Mg, Cr, Ti, Si or Y, and A = F, P or Cl; lithium nickel cobalt manganese composite oxide; And the formula _{Li 1 + x M 1-y} M 'y PO 4-z X z ( wherein, M = a transition metal, preferably Fe, Mn, Co or Ni, M' = Al, Mg or Ti, X = F, S or N, and -0.5? X? +0.5, 0? Y? 0.5, and 0? Z? 0.1), but the present invention is not limited thereto.

The conductive material is usually added in an amount of 1 to 30% by weight based on the total weight of the mixture including the cathode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The binder is a component which assists in bonding of the active material and the conductive material and bonding to the current collector, and is usually added in an amount of 1 to 30% by weight based on the total weight of the mixture containing the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (cmC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, Polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.

The filler is optionally used as a component for suppressing the expansion of the electrode, and is not particularly limited as long as it is a fibrous material without causing any chemical change in the battery. Examples of the filler include olefin-based polymerizers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

The negative electrode is prepared, for example, by applying a negative electrode mixture containing a negative electrode active material on a negative electrode collector and then drying the same. The negative electrode mixture may contain a conductive material, a binder, a filler, May be included.

The negative electrode collector is generally made to have a thickness of 3 to 500 mu m. The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery. Examples of the negative electrode current collector include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, copper or stainless steel Surface-treated with carbon, nickel, titanium, silver or the like, aluminum-cadmium alloy, or the like can be used. In addition, like the positive electrode collector, fine unevenness can be formed on the surface to enhance the bonding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams and nonwoven fabrics.

The negative electrode active material includes, for example, carbon such as non-graphitized carbon and graphite carbon including the above-described silicon-based compound; _{Li x Fe 2 O 3 (0≤x≤1} ), Li x WO 2 (0≤x≤1), Sn x Me 1-x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me' : Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, Halogen, 0 < x &lt; Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, Bi ₂ O ₅ and the like; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

The binder, the conductive material, and the components added as necessary are the same as those in the negative electrode.

In some cases, a filler may be optionally added as a component to suppress the expansion of the negative electrode. Such a filler is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery, and examples thereof include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

In addition, other components such as a viscosity adjusting agent, an adhesion promoter and the like may be further included as a selective or a combination of two or more.

The viscosity modifier may be added up to 30% by weight based on the total weight of the negative electrode mixture as a component for adjusting the viscosity of the electrode mixture so that the mixing process of the electrode mixture and the coating process on the current collector may be easy. Examples of such viscosity modifiers include carboxymethylcellulose, polyvinylidene fluoride and the like, but are not limited thereto. In some cases, the above-described solvent may play a role as a viscosity adjusting agent.

The adhesion promoter may be added in an amount of 10% by weight or less based on the binder, for example, oxalic acid, adipic acid, Formic acid, acrylic acid derivatives, itaconic acid derivatives, and the like.

The lithium salt-containing nonaqueous electrolyte solution is composed of an electrolyte solution and a lithium salt. As the electrolyte solution, a nonaqueous organic solvent, an organic solid electrolyte, and an inorganic solid electrolyte may be used.

Examples of the non-aqueous organic solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma -Butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane , Acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate Nonionic organic solvents such as tetrahydrofuran derivatives, ethers, methyl pyrophosphate, ethyl propionate and the like can be used.

Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, A polymer containing an ionic dissociation group and the like may be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can be used.

The lithium salt is a material that is readily soluble in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO 4, LiBF 4, LiB 10 Cl 10, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF _{6, LiSbF 6, LiAlCl 4,} CH 3 SO 3 Li, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide.

For the purpose of improving the charge / discharge characteristics and the flame retardancy, the electrolytic solution is preferably mixed with an organic solvent such as pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, Benzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, . In some cases, halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further added to impart nonflammability. In order to improve the high-temperature storage characteristics, carbon dioxide gas may be further added. FEC (Fluoro-Ethylene Carbonate, PRS (Propene sultone), and the like.

In a preferred _{embodiment, LiPF 6, LiClO 4, LiBF} 4, LiN (SO 2 CF 3) 2 , such as a lithium salt, a highly dielectric solvent of DEC, DMC or EMC Fig solvent cyclic carbonate and a low viscosity of the EC or PC of And then adding it to a mixed solvent of linear carbonate to prepare a lithium salt-containing non-aqueous electrolyte.

The present invention can also provide a battery pack including the cylindrical battery.

Specifically, the battery pack may be used as a power source for devices requiring high-temperature safety, long cycle characteristics, and high rate characteristics. Examples of such devices include a mobile device, a wearable device A power tool powered by an electric motor; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; And an energy storage system, but the present invention is not limited thereto.

The structure of these devices and their fabrication methods are well known in the art, and a detailed description thereof will be omitted herein.

As described above, the cylindrical battery according to the present invention includes a battery case having a gas removing layer formed on at least a part of the inside thereof, the gas removing layer including a carbon material, Explosion and the like can be prevented.

In addition, when the gas-removing layer is made of a material which is light and does not react with the internal materials of the battery, the space for storing the gas is large, so that the charge storage capacity per unit mass is excellent and the cell having a small mass per unit volume .

1 is a vertical sectional view of a battery case according to an embodiment.
2 is an exploded top plan view of a jelly-roll type electrode assembly according to one embodiment before winding.
3 is a front view of the jelly-roll type electrode assembly of FIG. 2 in a wound state.
4 is a vertical sectional view of a cylindrical battery according to one embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the detailed description of known functions and configurations incorporated herein will be omitted when it may unnecessarily obscure the subject matter of the present invention.

The same reference numerals are used for portions having similar functions and functions throughout the drawings. Throughout the specification, when a part is connected to another part, it includes not only a case where it is directly connected but also a case where the other part is indirectly connected with another part in between. In addition, the inclusion of an element does not exclude other elements, but may include other elements, unless specifically stated otherwise.

The present invention will be described in detail with reference to the drawings.

1 schematically shows a vertical sectional view of a battery case according to one embodiment.

Referring to FIG. 1, the battery case 100 has a structure in which a gas removing layer 110 is added to the inner surface 101. The gas removing layer 110 is formed on the entire inner surface 101 of the battery case 100. The gas removing layer 110 may be formed only on the cylindrical side surface of the battery case 100, The thickness of the gas removing layer formed on the cylindrical side surface portion may be equal to or different from the thickness of the gas removing layer formed on the circular bottom surface portion.

FIG. 2 schematically shows a disassembled plan view of a jelly-roll type electrode assembly according to one embodiment before rolling. FIG. 3 schematically shows a front view of a jelly- Respectively.

2 and 3, the jelly-roll type electrode assembly 200 is manufactured by stacking the anode 210 and the cathode 230 with the separator 220 interposed therebetween, and then winding the anode 210 and the cathode 230 in one direction. The positive electrode 210 is coated with a positive electrode mixture layer 212 on one or both surfaces of a positive electrode collector 211 and a positive electrode tab 213 is attached to an uncoated portion where the positive electrode mixture layer 212 is not formed .

The negative electrode 230 is coated with a negative electrode mixture layer 232 on one or both surfaces of the negative electrode collector 231 and the negative electrode tab 233 is attached to the uncoated portion where the negative electrode mixture layer 232 is not formed .

A gas removing layer 251 is formed on the outer surfaces of the positive electrode tabs 213 and the negative electrode tabs 233 exposed to the outside of the electrode assembly 200 while the electrode assembly 200 is wound, A gas removing layer 251 having a structure for covering the electrode assembly is added. However, unlike FIG. 3, a gas removing layer may be formed only on the electrode tabs, or a gas removing layer may be added only to the outer surface of the electrode assembly.

The gas-removing layer 251 is shown to surround the outer surface of the jelly-roll type electrode assembly 200 at 360 degrees. However, in order to prevent the electrode assembly from loosening, only the tape attached to the winding end of the jelly- .

The length of the degassing layer 251 parallel to the take-up shaft direction of the jelly-roll type electrode assembly 200 is shorter than that of the jelly roll type electrode assembly 200. However, A degassing layer may be added or a degassing layer having a length longer than the winding axial length of the jelly-roll type electrode assembly may be added.

Fig. 4 schematically shows a vertical sectional view of a cylindrical battery according to one embodiment.

4, the cylindrical battery 300 includes a battery case 301 housing the electrode assembly 310, a cap assembly 302 positioned at the open upper end of the battery case 301, And a lower insulating member 304 positioned on the lower surface of the electrode assembly 310. A gas removing layer 321 is formed on the lower surface of the upper insulating member 303, A gas removing layer 322 is formed on the upper surface of the lower insulating member 304.

4, a gas removing layer may be formed on at least a part of the lower surface 305 of the cap assembly 302 of the cylindrical battery 300, and the gasket layer may be formed on the outer surface of the electrode assembly 310, A gas-removing layer may be formed.

As described above, the present invention relates to a cylindrical battery in which a gas removing layer is formed on the inner surface of a battery case and / or on the outer surfaces of inner members housed in a battery, wherein the gas removing layer comprises a single wall carbon The present invention can provide a cylindrical battery including a gas-removing layer that does not react with an electrolyte solution without increasing the overall mass of the battery cell when the cell is formed of a nanotube or a three-dimensional network structure.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100, 301: Battery case
101: Inside surface of battery case
110, 251, 321, 322: gas removal layer
200, 310: jelly-roll type electrode assembly
210: anode
211: positive current collector
212: anode mixture layer
213:
220: Membrane
230: cathode
231: cathode collector
232: anode mixture layer
233: negative electrode tab
300: Cylindrical battery
302: cap assembly
303: upper insulating member
304: Lower insulating member
305: the lower surface of the cap assembly

Claims (9)

A cylindrical battery in which an electrode assembly is housed together with an electrolyte,
A battery case accommodating the electrode assembly and made of a metal material;
A cap assembly positioned at an open upper end of the battery case;
An insulation member positioned at an upper portion and / or a lower portion of the electrode assembly to ensure insulation of the electrode assembly; And
A gas removing layer formed on at least a part of the inside of the battery case and including a carbon material;
. The cylindrical battery according to claim 1, wherein the gas removal layer is formed in a film form, a tape form using an adhesive, or a sprayed spray. The battery pack according to claim 1, wherein the gas removing layer is formed on at least one portion selected from the group consisting of an inner side wall of the battery case, an electrode tab attached to the electrode assembly, a lower surface of the cap assembly, and a surface of the insulating member With a cylindrical battery. The cylindrical battery according to claim 1, wherein the gas removal layer comprises a single-walled carbon nanotube (SWNT) or a carbon material having a three-dimensional network structure. The cylindrical battery according to claim 4, wherein the single-walled carbon nanotube is coated with titanium (Ti). The cylindrical battery according to claim 1, wherein the battery case is electrically coupled to a negative electrode tab of the electrode assembly. The cylindrical battery according to claim 1, wherein the gas-removing layer further includes a structure surrounding a part of an outer surface of the electrode assembly. The cylindrical battery according to claim 1, wherein the gas-removing layer is made of a material that does not generate a chemical reaction with the electrolyte solution. A battery pack comprising the cylindrical battery according to any one of claims 1 to 8.

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