KR20150028138A - Battery Cell of Increased Capacity and Device Comprising the Same - Google Patents

Abstract

The present invention relates to a battery cell of increased capacity and a device comprising the same. More particularly, the present invention relates to a battery cell and a device comprising the same. The battery includes an electrode assembly and a rectangular battery case formed in the electrode assembly. The battery case of the battery cell includes a pair of long sides which face each other on a horizontal cross section and a pair of short sides which face each other. An indent part which is thinner than the average thickness (t1) of the long side is formed on at least one of the long sides.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery cell having increased capacity,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery cell having increased capacity and an apparatus including the same, and more particularly, to a battery cell including an electrode assembly and a prismatic battery case having the electrode assembly therein, And a pair of long side portions facing each other on the cross section and a pair of short side portions facing each other, wherein at least one of the long side portions is provided with a recess portion thinner than the average thickness t ₁ of the long side portion To a battery cell and an apparatus including the same.

The secondary battery is classified into a cylindrical battery, a prismatic battery and a pouch-shaped battery according to the shape of the case in which the electrode assembly of the anode / separator / cathode is built. Demand is growing significantly.

Generally, a prismatic battery includes a jelly-roll type or a stacked type anode / separator / cathode electrode assembly in a square-shaped battery case, an open top is covered with a top cap, an electrolyte is injected through an electrolyte injection port on the top cap, .

FIG. 1 is a schematic view of a prismatic battery incorporating a conventional jelly-roll type electrode assembly.

1, the prismatic battery 50 includes a jelly-roll 10 housed in a rectangular metal case 20, and a protruding electrode terminal (for example, a negative terminal: 32 are formed on the top surface of the top cap 30.

The negative electrode of the jelly-roll 10 is electrically connected to the lower end of the negative electrode terminal 32 on the top cap 30 via the negative electrode tab 12, And is insulated from the cap 30. On the other hand, another electrode (for example, an anode) of the jelly-roll 10 is electrically connected to the top cap 30 whose anode tab 14 is made of a conductive material such as aluminum and stainless steel Itself forms a bipolar terminal.

In order to ensure electrical insulation between the jelly-roll 10 and the top cap 30 except for the electrode taps 12 and 14, a sheet-like insulating member 20 is interposed between the rectangular case 20 and the jelly- The top cap 30 is mounted and welded along the contact surfaces of the top cap 30 and the case 20. [ Then, an electrolyte is injected through the electrolyte injection port 43, a metal ball (not shown) is welded and sealed, and a welded portion is coated with epoxy or the like to complete the battery.

On the other hand, in order to maximize the capacity of the battery and to minimize the size of the battery in accordance with the trend of downsizing and thinning of the battery, it is required to design a battery case as thin as possible. However, in the case of using such a thin-walled battery case, in the process of manufacturing the battery, not only the thickness of the metal plate forming the battery case is reduced to the inside, but also the mechanical strength is lowered and the wall is easily deformed by the internal pressure of the battery, There is a problem that the property is deteriorated.

In this connection, some prior arts have proposed a technique of increasing the capacity of the battery by thinning the side wall of the battery case. For example, Korean Patent Laid-Open Publication No. 2001-0019580 has a pair of long side walls and a pair of short side walls formed at ends of the long side walls, wherein the short side walls have a thickness Discloses a thinly formed battery case.

However, since the single side wall of the battery case corresponds to the end portion of the side wall, when the battery is dropped or moved, external impact is likely to be concentrated, and relatively high mechanical rigidity is required. Therefore, although the prior art can improve the battery capacity of the battery case to some extent, there is a problem in the stability of the battery. In addition, since it has a non-uniform shape in the shape of an arc on the short side wall, it is difficult to reduce the thickness, and it is difficult to expect an increase in the effective cell capacity due to the decrease in thickness. There is a limit that can not be done.

Accordingly, there is a high need for a technique that can increase the capacity of the battery while maintaining safety by more effectively utilizing the internal space of the battery case in accordance with the trend of maximizing the capacity while minimizing the size of the battery.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems of the prior art and the technical problems required from the past.

The inventors of the present application have conducted intensive research and various experiments and have found that when the specific area of at least one long side of the battery case is made thinner than the average thickness t ₁ of the long side part, the internal volume of the battery case is increased, The amount of the positive electrode active material, the negative electrode active material, and the electrolytic solution to be contained is relatively increased, thereby maximizing the capacity of the battery. Thus, the present invention has been accomplished.

Therefore, the battery cell according to the present invention includes an electrode assembly and a prismatic battery case in which the electrode assembly is embedded. The battery case has a pair of long side portions facing each other on a horizontal cross section, Wherein at least one of the long side portions is formed with a recessed portion that is thinner than an average thickness t ₁ of the long side portion.

The battery cell according to the present invention is characterized in that at least one of the long side portions which are not susceptible to mechanical impact is formed with a recessed portion which is thinner than the average thickness t ₁ of the long side portion in consideration of the position and thickness of the electrode tab of the electrode assembly. The stability and manufacturability of the battery can be ensured while the external volume and the shape are kept the same, and the internal space of the battery case can be increased, so that the capacity of the battery can be maximized.

The present inventors have found that the battery cell according to the present invention can be applied to a case where the size of the battery case is 52 mm in width x 51.8 mm in width x 55.7 mm in height and the thickness of the recessed portion which is thinner than the average thickness t ₁ It was confirmed that the capacity was increased by 4.5% or more as compared with the battery cell having the constant thickness t _{a at the} long side.

In one specific example, the shape of the short side of the battery case may be a square shape or an arc shape. Specifically, when the short side of the battery case is an arc shape, the center of the arc is located in the direction of the center axis of the battery case Structure.

The battery case may be made of a metal material, for example, stainless steel, aluminum, or an aluminum alloy to effectively protect the battery case from external mechanical impacts and to block air and foreign substances that may enter the battery case.

In one specific example, the indentation may preferably be formed on the long side at a position corresponding to the electrode tab located on the outer surface of the electrode assembly.

The thickness of the sidewall of the battery case may be suitably adjusted in consideration of the desired mechanical strength and the battery capacity. In one specific example, the thickness t _d of the indent is, for example, the average thickness t ₁ ). ≪ / RTI > At this time, when the average thickness t _{1 of the} long side portion is smaller than 30%, the desired mechanical strength can not be attained and it can be easily deformed when an external impact is applied due to falling of the battery or the like, Can be degraded. On the other hand, when the average thickness of the long side portion is larger than 80%, it is difficult to exhibit the desired battery capacity increasing effect.

The width w _d of the indent may be formed to have an appropriate width considering the position of the electrode tab. For example, the width w d may be 10 to 90% of the width w _{1 of the} long side.

Meanwhile, in order to safely insert the electrode assembly into the battery case during the manufacturing process of the battery cell, the size of the electrode assembly is smaller than the internal size of the battery case so that the battery case and the electrode assembly are inserted with a predetermined distance. At this time, the predetermined distance is referred to as an insertion tolerance.

In one specific example, the insertion tolerance, which is the distance between the outer surface of the electrode assembly and the inner surface of the long side, may be 0.100 mm or more to reduce the defect rate in the manufacture of the battery cell and facilitate insertion of the electrode assembly.

In one specific example, the electrode assembly has a structure in which one positive electrode sheet and one negative electrode sheet are wound with a separator interposed therebetween, and an electrode tab is attached to the non-coated portion of the current collector to which the electrode active material is not applied The positive electrode tab or the negative electrode tab is attached to the uncoated portion of the electrode current collector at the winding start point and is located at the winding center portion of the electrode assembly and is opposite to the electrode tab at the winding center portion The tab of the polarity is attached to the solid portion of the electrode current collector at the winding end point and can be located on the outer surface of the electrode assembly.

The positive electrode is prepared, for example, by coating a mixture of a positive electrode active material, a conductive material and a binder on a positive electrode current collector, and then drying the mixture. Optionally, a filler may be further added to the mixture.

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 current collector may have fine irregularities on the surface thereof to increase the adhesive force of the cathode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are 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 20 wt% 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 collector, and is usually added in an amount of 1 to 20% 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 anode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

The negative electrode is fabricated by applying an anode active material on an anode current collector and drying the anode active material, and may further include the above-described components as needed.

The negative electrode collector is generally made to have a thickness of 3 to 500 mu m. Such an anode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery, and may be formed of a material such as copper, stainless steel, aluminum, nickel, titanium, fired carbon, surface of copper or stainless steel A surface treated with carbon, nickel, titanium, silver or the like, an 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 may include, for example, carbon such as non-graphitized carbon or graphite carbon; _{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 &lt; 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, and Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

The separator is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 mu m and the thickness is generally 5 to 300 mu m. Such separation membranes include, for example, olefinic polymers such as polypropylene, which are chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane.

In one specific example, the battery cell may be a lithium secondary battery, but the kind thereof is not particularly limited.

The lithium secondary battery may include the electrode assembly and a non-aqueous electrolyte containing a lithium salt.

The lithium-containing non-aqueous electrolyte is composed of a nonaqueous electrolyte and lithium. As the non-aqueous electrolyte, a non-aqueous electrolyte, a solid electrolyte, an inorganic solid electrolyte and the like are used.

Examples of the nonaqueous electrolytic solution include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, But are not limited to, lactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, Nitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives , Tetrahydrofuran derivatives, ether, 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, Polymers containing ionic dissociation groups, and the like can 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 3 Li, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide have.

For the purpose of improving charge / discharge characteristics, flame retardancy, etc., non-aqueous electrolytes may be used in the form of, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride and the like are added It is possible. In some cases, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart nonflammability, or a carbon dioxide gas may be further added to improve high-temperature storage characteristics.

The present invention can also be a device including the battery cell as a power source, for example, a mobile phone, a notebook, an MP3 player, a PMP, a DVR, a smart pad, a GPS system, a tablet computer, However, the present invention is not limited thereto.

As described above, the battery cell according to the present invention includes a pair of long side portions facing each other on a horizontal cross section and a pair of short side portions facing each other, and the position of the electrode tab and the thickness consider the case of using a battery case is formed additional thin recessed than the long portion average thickness (t _1), increases the volume of the battery case and, accordingly, increases the amount of positive electrode active material, negative electrode active material and the electrolytic solution to the cell capacity a There is an effect that can be increased.

1 is an exploded perspective view of a general structure of a conventional jelly-roll type prismatic battery;
2 is a perspective view illustrating a structure in which an electrode assembly is inserted into a battery case of a battery cell according to a first comparative example;
3 is a schematic view of the structure of the jelly-roll type electrode assembly before winding;
4 is a front schematic view of a battery case according to a first comparative example;
5 is a front schematic view of a battery case according to a second comparative example;
6 is a front schematic view of a battery case according to a first embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings, but the scope of the present invention is not limited thereto.

FIG. 2 is a perspective view of a structure in which an electrode assembly is inserted into a battery case of a battery cell according to a first comparative example based on the prior art.

2, the battery cell 200 includes a jelly-roll type electrode assembly 300 and a prismatic battery case 220 in which the electrode assembly 300 is embedded. A pair of long side portions 221 and 222 facing each other on a horizontal section and a pair of short side portions 223 and 224 facing each other.

2, the range of the long side portions 221 and 222 and the short side portions 223 and 224 of the outer surface of the battery case 220 is indicated by a dotted line for convenience of explanation.

The pair of short side portions 223 and 224 are formed in an arc shape and the center of the arc is located in the direction of the central axis of the battery case 220.

Fig. 3 shows a schematic view of the structure of the jelly-roll type electrode assembly before winding.

3, the jelly-roll type electrode assembly 300 includes a positive electrode sheet 350 in which a positive electrode active material 353 is applied on both surfaces of a positive electrode collector 352 and a negative electrode collector 360 364 are coated with a negative electrode active material 365 and wound in the direction of the arrow with the separator 340 therebetween. The uncoated portion 370 in which the positive electrode active material 353 is not applied is formed on one end of the positive electrode collector 352 and the negative electrode active material 365 is not coated on one end of the negative electrode collector 360 An uncoated portion 380 is formed. The positive electrode tab 312 is formed so as to protrude partially from the upper portion of the non-coated portion 370 of the positive electrode collector 352. The negative electrode tab 314 is formed on the upper portion of the non-coated portion 380 of the negative electrode collector 364, Respectively.

The negative electrode tab 314 of the electrode assembly 300 is attached to the uncoated portion 380 of the negative electrode current collector 364 at the winding starting point and is positioned at the winding center portion of the electrode assembly 300, Is attached to the non-coated portion (370) of the positive electrode collector (352) at the winding end point and is located on the outer surface of the electrode assembly (300).

Fig. 4 is a front view of the battery case according to the first comparative example, Fig. 5 is a front view of the battery case according to the second comparative example, and Fig. 6 is a schematic front view of the battery case according to the first embodiment. .

4 and 5, the battery cases 220 and 420 include a pair of long side portions 221 and 421 facing each other on a horizontal cross section and a pair of short side portions 223 and 423 facing each other The battery case 420 shown in FIG. 5 has _a thickness t _{c that} is smaller than the thickness t _a of the side wall of the battery case 220 shown in FIG. 4, The electrode assemblies 300 and 430 are inserted into the battery cases 220 and 420 while the insertion tolerances P ₁ and P ₂ are set to 0.100 mm irrespective of the thicknesses t _a and t _c of the long side portions 220 and 420, Respectively.

6, the battery case 120 of the battery cell 100 is formed with the indentations 125 and 126 which are thinner than the average thickness t ₁ of the long side portions 121 and 122, respectively, The electrode assembly 130 is formed on the long side portion 122 at a position corresponding to the positive electrode tab 114 located on the outer surface of the electrode assembly 130 and has an insertion tolerance P ₃ of 0.100 mm or more 130 are inserted into the battery case 122.

The thickness t _d of the indentations 125 and 126 is 30 to 80% of the average thickness t ₁ of the long side portions 121 and 122 and the thickness t _d of the indentations 125 and 126 The width w _d is comprised of 10 to 90% of the width w ₁ of the long side portions 121 and 122.

Therefore, since the indentation 126 is formed on the long side portion 122 at a position corresponding to the positive electrode tab 114 protruding from the outer surface of the electrode assembly 130, the entire thickness of the side wall of FIG. 5 is reduced There is an advantage that the capacity of the battery case can be increased more effectively while satisfying the insertion tolerance more appropriate than the case of the case.

Hereinafter, the content of the present invention will be described in detail by way of examples, but the scope of the present invention is not limited thereto.

&Lt; Example 1 >

Manufacture of battery case

A battery case made up of sidewalls having an indentation thickness t _d of 0.20 mm and an average short side thickness of 0.27 mm was subjected to deep drawing and pressing using an Ni-plated SPCE (cold rolled steel sheet) (Width 5.2 mm, width 51.88 mm, height 55.7 mm).

Manufacture of Secondary Battery

The positive electrode sheet and the negative electrode sheet were produced by applying the active material to the positive and negative current collectors respectively and then subjected to the rolling compression process. The positive electrode tab and the negative electrode tab were welded to the uncoated portions of the positive electrode collector and the negative electrode collector, The negative electrode sheet was wound up with a separator interposed therebetween to manufacture a jelly-roll type electrode assembly. The jelly-roll type electrode assembly manufactured as described above is inserted into the battery case, a sheet-shaped insulating member is inserted between the rectangular case and the jelly-roll, and then the top cap is mounted, welded along the contact surface between the top cap and the case, Respectively. Then, the electrolyte was injected through the electrolyte injection hole, and the metal ball was welded and sealed, and the welded portion was coated with epoxy or the like to manufacture a secondary battery.

&Lt; Comparative Example 1 &

A secondary battery was fabricated in the same manner as in Example 1, except that the thickness of the long side portion of the battery case was constantly adjusted to 0.27 mm and no indented portion was formed.

&Lt; Comparative Example 2 &

A secondary battery was fabricated in the same manner as in Example 1, except that the thickness of the long side portion of the battery case was constantly adjusted to 0.24 mm, and no indented portion was formed.

The specifications of the secondary batteries manufactured in Example 1, Comparative Example 1 and Comparative Example 2 are shown in Table 1 below.

<Experimental Example 1>

Thirty secondary batteries were manufactured according to the manufacturing method of Example 1, Comparative Example 1 and Comparative Example 2, and the capacity of each secondary battery was measured and the average value thereof was calculated. The results are shown in Table 2 below .

As shown in Table 2, the secondary battery of Example 1 having a reduced thickness of the indentation portion compared to the battery of Comparative Example 2, in which the thickness of the long side portion of the battery case was reduced based on the average battery capacity of Comparative Example 1, Showed a high capacity increase rate. In detail, it can be seen that the battery capacity of Example 1 was increased by about 4.9% as compared with Comparative Example 1.

Therefore, the secondary battery according to the present invention can effectively increase the capacity of the battery as compared with a case where the thickness of the side wall is uniformly thinned while ensuring the insertion tolerance for facilitating the manufacturing process of the battery by making a part of the long side portion thinner .

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

Claims (12)

Wherein the battery case includes a pair of long side portions facing each other on a horizontal cross section and a pair of short side portions facing each other on the horizontal cross section, in at least one battery cell, it characterized in that the recess portion is formed thinner than the long portion average thickness (t ₁₎ of the portions. The electrode assembly according to claim 1, wherein the electrode assembly has one electrode sheet and one negative electrode sheet wound with the separator interposed therebetween, and the electrode tab is attached to the non-coated portion of the current collector to which the electrode active material is not applied Wherein the battery cell is made of a metal. The battery pack according to claim 2, wherein the electrode assembly has a positive electrode tap or a negative electrode tab attached to the non-solid portion of the electrode current collector at the winding start point and located at the winding center portion of the electrode assembly, And is attached to an uncoated portion of the electrode current collector at an end of winding and is located on the outer surface of the electrode assembly. The battery cell according to claim 1, wherein the battery case is made of a metal material. The battery cell according to claim 1, wherein the short sides are angular or arc-shaped, and the center of the arc is located in the center axis direction of the battery case. The battery cell according to claim 1, wherein the indent is formed on a long side portion at a position corresponding to an electrode tab located on an outer surface of the electrode assembly. The battery cell according to claim 1, wherein the thickness t _d of the indent is 30 to 80% of an average thickness t ₁ of the long side portion. The battery cell according to claim 1, wherein the width w _d of the indent is 10 to 90% of the width w ₁ of the long side portion. The battery cell according to claim 1, wherein an insertion tolerance, which is a distance between an outer surface of the electrode assembly and an inner surface of the long side portion, is 0.100 mm or more. The battery cell according to claim 1, wherein the battery cell is a lithium secondary battery. A device comprising a battery cell according to any one of claims 1 to 10 as a power source. 12. The device of claim 11, wherein the device is selected from the group consisting of a cell phone, a smart pad, a tablet computer, and a lab-top computer.

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