KR20170045475A - Battery Cell Having Folded Portion for Sealing - Google Patents

Abstract

The present invention provides a battery cell which includes: an electrode assembly comprising an anode, a cathode, and a separation film interposed between the anode and the cathode; a first battery case including a storage part in which the electrode assembly is embedded; and a second battery case installed on the first battery case to surround the storage part. In a part in which the first and second battery cases are in contact with each other, a folding part for sealing is formed in such a shape that the outer edge of the first battery case surrounds the circumferential end of the second battery case. In the folding part for sealing, the first and second battery cases are welded with each other. As such, the present invention is capable of reducing manufacturing costs.

Description

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

The present invention relates to a battery cell including a sealing folding portion.

Secondary batteries are widely used as power sources for mobile devices such as mobile phones, notebooks, and camcorders. In particular, the use of lithium secondary batteries is rapidly increasing due to the advantages of high operating voltage and high energy density per unit weight.

Such a lithium secondary battery may be classified as a lithium ion battery, a lithium ion polymer battery, or a lithium polymer battery depending on the configuration of an electrode and an electrolytic solution. The lithium secondary battery is less liable to leak electrolyte, Is increasing.

Lithium ion polymer battery (LiPB) is a structure in which an electrode assembly (electrode and anode) and a separator are thermally fused to an electrode assembly impregnated with an electrolytic solution. The electrode assembly is mainly used in a sealed form in an aluminum laminate sheet pouch case. Therefore, a lithium ion polymer battery is often referred to as a pouch type battery.

FIG. 1 schematically shows a typical structure of a typical pouch-type battery including a stacked electrode assembly, and FIG. 2 is a schematic bottom view of the pouch-shaped battery of FIG.

1, the battery cell 10 includes an electrode assembly 30 including a positive electrode, a negative electrode, and a separator disposed therebetween in a pouch-shaped battery case 20, The tabs 31 and 32 are welded to the two electrode leads 40 and 41 and sealed (sealed) so as to be exposed to the outside of the battery case 20.

The battery case 20 is made of a soft packaging material such as an aluminum laminate sheet and includes a case body 21 including a concave shaped storage portion 23 on which the electrode assembly 30 can be seated, And a lid 22 to which one side is connected.

The electrode assembly 30 used in the battery cell 10 may have a jelly roll structure or a stack / folding structure other than the stack structure as shown in FIG. In the stacked electrode assembly 30, a plurality of positive electrode tabs 31 and a plurality of negative electrode tabs 32 are welded to the electrode leads 40 and 41, respectively.

Referring to Fig. 2 together with Fig. 1, the battery cell 10 presses and heats the both sides and the upper side of the battery case 20 by press to seal the electrode assembly completely from the outside. In order to seal both sides of the battery case 20 by the press, the sealing portions 24 are formed at both sides of the accommodating portion 23. In the conventional general structure, the sealing portion 24 is formed with a width W1 of 5 to 7 mm in size.

As described above, the step of sealing and pressing the battery case by pressurizing and heating by pressing is required to additionally form a sealing part separately from the housing part for housing the electrode assembly in the battery case, so that the amount of the base material entering the battery case is increased there is a problem.

Further, since the laminate sheet as the base material of the battery case is made of a soft packaging material, a part of the sealing portion may not be completely sealed due to breakage or puncture during pressing and heating by pressing. As a result, there is a problem that the electrolyte solution in the battery cell is leaked, which causes the manufacturing defect rate to increase.

Therefore, a battery cell capable of solving the above problems is very necessary.

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

It is an object of the present invention to provide a battery cell capable of minimizing consumption of base material generated in a process of sealing a battery case during a battery cell manufacturing process and reducing manufacturing cost, .

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

An electrode assembly having a separator structure sandwiched between an anode, a cathode, and an anode and a cathode;

A first battery case having a housing portion in which the electrode assembly is housed; And

A second battery case mounted on the first battery case to enclose the storage unit;

Lt; / RTI >

Wherein an outer circumferential portion of the first battery case surrounds an outer circumferential end portion of the second battery case at a portion where the first battery case and the second battery case are in contact with each other and a sealing folding portion is formed in the sealing folding portion, The battery case and the second battery case may have a structure in which they are mutually coupled by welding.

Therefore, in the battery cell according to the present invention, the outer circumferential portion of the first battery case forms the sealing folding portion in such a manner as to surround the outer circumferential end portion of the second battery case, so that the conventional sealing process is performed, Since the sealing folding portion having a compact structure is formed unlike the case in which the sealing portion is formed wide in the case, the consumption of the base material occurring in the process of sealing the battery case can be minimized and the manufacturing cost can be reduced.

In addition, by joining the first battery case and the second battery case by welding the sealing folding portion formed by the winding structure, it is possible to prevent leakage of the electrolyte solution by lowering the defective sealing ratio of the battery case, have.

Wherein the electrode assembly is a folding structure, a stacking structure, a stacking / folding structure, or a lamination / stacking structure.

The electrode assembly may have a folding structure, a stacking structure, or a stacking / folding structure, or a lamination / stacking structure.

The electrode structures of the folding type, the stacking type, the stacking / folding type, and the lamination / stacking type will be described in detail as follows.

First, a unit cell of a folding structure can be produced by coating a mixture containing an electrode active material on each metal current collector, placing the separator sheet between a cathode and an anode in the form of a sheet dried and pressed, and winding .

The unit cells of the stacked structure are formed by coating each electrode collector with an electrode mixture, drying and pressing the separator, and separating the positive and negative plates with a predetermined size corresponding to the positive and negative plates, And then laminating them.

The unit cell of the stack / folding type structure includes two or more unit cells in which the anode and the cathode face each other and in which two or more electrode plates are stacked, and the unit cells are wound with at least one separating film in a non- Or by bending the separation film to a size of the unit cell and interposing it between the unit cells.

In some cases, the positive electrode and the negative electrode face each other, and one or more single electrode plates may be further included between any unit cells and / or an outer surface of the outermost unicell.

The unit cell may be an S-type unit cell in which the outermost electrode plates on both sides have the same electrode, and a D-type unit cell in which the outermost electrode plates on opposite sides have opposite electrodes.

The S type unit cell may be an SA type unit cell in which the outermost electrode plates on both sides are the anode, and an SA type unit cell in which the outermost electrode plates on both sides are the cathodes.

The unit cells of the lamination / stacked structure are obtained by coating each metal current collector with an electrode mixture, drying, pressing and cutting to a predetermined size, sequentially forming a negative electrode from the bottom, a separator, And a separator is laminated thereon.

In one embodiment of the present invention, the first battery case and the second battery case may be made of different materials.

For example, the first battery case may be made of a metal material.

Specifically, the first battery case may be formed of a metal plate, and may have a structure in which the housing portion is recessed corresponding to the shape of the electrode assembly.

The first battery case may be made of aluminum or an aluminum alloy, but is not limited thereto, as long as it is easy to form a storage portion and can provide a desired rigidity.

The inner surface of the first battery case may be coated with an electrically insulating material so that the first battery case is electrically insulated from the electrode assembly contained in the storage portion.

Specifically, the electrically insulating material may be a polyolefin resin, but is not limited thereto as long as it is easy to coat the inner surface of the battery case and can provide electrical insulation between the battery case and the electrode assembly.

Unlike the case where the first battery case is made of a metal material, the second battery case may be composed of a laminate sheet including a resin outer layer, a barrier metal layer, and a heat-meltable resin sealant layer.

Since the resin outer layer must have excellent resistance from the external environment, it is necessary to have a tensile strength and weather resistance higher than a predetermined level. In this respect, polyethylene terephthalate (PET) and stretched nylon film can be preferably used as the polymer resin of the outer resin layer.

The barrier metal layer may preferably be made of aluminum so as to exhibit a function of improving the strength of the battery case, in addition to a function of preventing foreign matter such as gas or moisture from leaking or leaking.

The resin sealant layer may preferably be a polyolefin resin having low heat absorbability (thermal adhesiveness), low hygroscopicity to suppress penetration of an electrolyte solution, and not being swollen or eroded by an electrolytic solution, Preferably, lead-free polypropylene (CPP) can be used.

The second battery case may have a planar sheet-like sheet structure, and the outer circumferential surface of the second battery case may have a shape corresponding to a planar shape of the first battery case. The planar area of the second battery case may be 95 to 100% based on the planar area of the first battery case.

In one embodiment of the present invention, in the sealing folding portion, the outer peripheral portion of the first battery case and the outer peripheral end of the second battery case may be integrally joined by laser welding.

In one embodiment, the laser welding may be performed on the upper surface of the battery cell by a laser welder. That is, since the welding is performed on the upper surface of the battery cell, the welding portion can be formed on the upper surface of the sealing folding portion along the outer periphery of the first battery case and the second battery case.

In another embodiment, the laser welding may be performed from the side of the battery cell by a laser welder. That is, the laser welding may be performed from the side surface of the sealing folding portion exposed on the vertical plane. In such a laser process, the welding portion may be formed only inside the sealing folding portion.

Specifically, in the sealing folding portion, the outer peripheral portion of the first battery case located on the outer side of the sealing folding portion is first melted by the heat of the laser, and then the outer peripheral end portion of the second battery case located on the inner side of the sealing folding portion melts , The outer circumferential portion of the first battery case and the outer circumferential end portion of the second battery case can be integrally coupled.

When the second battery case is composed of a laminate sheet including a resin outer layer, a barrier metal layer, and a heat-meltable resin sealant layer, the resin outer layer and the resin sealant layer are melted by heat, The first battery case and the second battery case can be joined by laser welding in a state in which they are in contact with the case.

The electrode terminal of the electrode assembly may protrude from one side or the other side of the first battery case and the second battery case. In other words, when the battery cell has a rectangular shape in a plan view and forms four sides, the electrode terminal is electrically connected to a first side, a second side, a third side, or a fourth side of the first battery case and the second battery case As shown in Fig.

The cathode terminal may protrude from one side of the electrode terminal, and the cathode terminal may be formed on one side adjacent to the one side or one side opposite to the one side.

The side surfaces of the first battery case and the second battery case where the electrode terminals protrude may be heated and pressed by a press to be adhered and sealed.

The sides where the electrode terminals of the first battery case and the second battery case protrude may be limited in performing laser welding at the electrode terminal formation sites. Therefore, only the side where the electrode terminals of the first battery case and the second battery case are protruded can be heated and pressed by a press to adhere and seal the corresponding portion.

In the sealing folding portion, the outer peripheral portion of the first battery case may be bent so as to be in contact with the outer surface of the second battery case, which is the opposite surface of the storage portion. That is, the sealing folding unit may be disposed on the upper surface of the second battery case.

In one embodiment of the present invention, the width of the sealing folding portion may be 1% to 5% of the width of the second battery case. When the width of the sealing folding portion is less than 1% of the width of the second battery case, the sealing folding portion may be formed to be small, which may be difficult to perform laser welding. On the other hand, when the width of the sealing folding portion is larger than 5% of the width of the second battery case, the size of the sealing folding portion is unnecessarily increased, so that the limitation on the construction of the battery cell having a compact structure This can be.

Specifically, the width of the sealing folding portion may be in the range of 1 mm to 2 mm, so that the base material consumed in the sealing process of the battery case can be minimized as compared with the conventional general battery cell, A battery cell having a structure can be constituted.

In one embodiment of the present invention, the sealing folding portion may have a rectangular or square shape on a vertical section, but may also be formed in a circular, elliptical or polygonal shape.

The battery cell may be a lithium secondary battery, specifically, a lithium ion battery or a lithium ion polymer battery.

Generally, a lithium secondary battery is composed of a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte containing a lithium salt.

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 active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _{2 -x} O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; A Ni-site type lithium nickel oxide expressed by the formula LiNi _1-x M _x O ₂ (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); Formula _{LiMn 2-x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like. However, the present invention is not limited to these.

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 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 manufactured by applying and drying a negative electrode active material on a negative electrode collector, and if necessary, the above-described components may be selectively included.

Examples of the negative electrode active material include carbon such as non-graphitized carbon and 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 < 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 separation membrane 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.

The non-aqueous electrolyte solution containing a lithium salt is composed of a polar organic electrolyte and a lithium salt. As the electrolytic solution, a non-aqueous liquid electrolytic solution, an organic solid electrolyte, an inorganic solid electrolyte and the like are used.

Examples of the nonaqueous liquid electrolytic solution 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, 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 the charge-discharge characteristics and the flame retardancy, the non-aqueous liquid electrolyte may contain, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. 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 also provides a battery pack including at least two battery cells.

The present invention also provides a device including the battery pack as a power source.

The device may be selected from a cell phone, a wearable electronic device, a portable computer, a smart pad, a netbook, a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, and a power storage device.

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, in the battery cell according to the present invention, the outer peripheral portion of the first battery case forms the sealing folding portion in such a manner as to surround the outer peripheral end portion of the second battery case, Since the sealing folding portion is formed in a compact structure unlike the case where the sealing portion is formed to be wide in the battery case to pressurize the battery case, consumption of the base material occurring in the process of sealing the battery case can be minimized and the manufacturing cost can be reduced.

In addition, by joining the first battery case and the second battery case by welding the sealing folding portion formed by the winding structure, it is possible to prevent leakage of the electrolyte solution by lowering the defective sealing ratio of the battery case, have.

1 is an exploded view of a conventional pouch type battery;
2 is a bottom view of the pouch type battery 1;
3 is a vertical cross-sectional view of a battery cell according to one embodiment of the present invention;
FIG. 4 is an enlarged view of a state before welding (a) and a state after welding (b) in the "A" region of FIG. 3;
5 is a bottom view of the battery cell of Fig. 3;
6 is a vertical cross-sectional view of a battery cell according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

FIG. 3 schematically shows a vertical cross-sectional view of a battery cell according to an embodiment of the present invention. FIG. 4 is an enlarged view of a state before welding (a) and a state after welding (b) Fig. 5 schematically shows a bottom view of the battery cell of Fig. 3. As shown in Fig.

3 to 5, the battery cell 100 includes a first battery case 110, a second battery case 120, and an electrode assembly 130.

The first battery case 110 is made of an aluminum-based metal plate and is formed so that the storage portion 111 is recessed corresponding to the shape of the electrode assembly 110. The inner surface of the first battery case 110 is coated with a coating part 112 made of a polyolefin resin, which is an electrically insulating material, for electrical insulation from the electrode assembly 130.

The electrode assembly 130 includes a positive electrode, a negative electrode, and a separator structure interposed between the positive electrode and the negative electrode. The electrode assembly 130 is embedded in a storage portion 111 formed in the first battery case 110.

The second battery case 120 is mounted on the upper portion of the first battery case 110 so as to surround the storage unit 111 in a state where the electrode assembly 130 is embedded in the first battery case 110.

The second battery case 120 is composed of a laminate sheet including a resin outer layer 121, a barrier metal layer 122, and a heat-meltable resin sealant layer 123, and has a planar sheet-like sheet structure . The planar shape of the second battery case 120 is a rectangular shape corresponding to the planar shape of the first battery case 110.

In the sealing folding unit 140, the outer peripheral portion of the first battery case 110 and the outer peripheral end of the second battery case 120 are integrally joined by laser welding.

The sealing folding unit 140 is configured such that the outer circumferential portion of the first battery case 110 surrounds the outer circumferential end of the second battery case 120 in the state (a) before welding.

The outer peripheral portion of the first battery case 110 located on the outer side of the sealing folding portion 140 is first melted by the heat of the laser and then the second folding portion 140 is positioned on the inner side of the sealing folding portion. The resin outer layer 121 and the resin sealant layer 123 of the case 120 are melted and moved to the inside of the sealing folding part 140. The outer peripheral part of the melted first battery case 110 is melted in the second battery case 120). &Lt; / RTI &gt; After the welding process as described above, the sealing folding unit 140 has the same structure as the state (b) after welding.

The electrode terminal 131 of the electrode assembly 130 protrudes from the upper side of the first battery case 110 and the second battery case 120.

The first electrode terminal of the first battery case and the second electrode terminal of the second battery case may protrude from the electrode terminals of the first battery case and the second battery case, Only the side where it is made is heated and pressed by a press to be adhered and sealed.

The width W2 of the sealing folding portion 140 is 1 mm which is 1% of the width W3 of the second battery case 120. [ Accordingly, the base material consumed in the sealing process of the battery case can be minimized as compared with the conventional general battery cell, and a battery cell having a compact structure can be constituted.

The sealing folding portion 140 is formed in a rectangular shape on a vertical section.

6 is a vertical cross-sectional view of a battery cell according to another embodiment of the present invention.

6, the outer peripheral portion of the first battery case 210 in the sealing folding portion 240 is bent so as to contact the upper and outer surfaces of the second battery case 220, which is the opposed surface of the storage portion 211. [ Accordingly, the sealing folding unit 240 is located on the upper surface of the second battery case 220. [

The remaining structure except for the structure in which the sealing folding part 240 is located on the upper surface of the second battery case 220 is the same as the embodiment described with reference to FIGS. 3 to 5, and a description thereof will be omitted.

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 (20)

An electrode assembly having a separator structure sandwiched between an anode, a cathode, and an anode and a cathode;
A first battery case having a housing portion in which the electrode assembly is housed; And
A second battery case mounted on the first battery case to enclose the storage unit;
Lt; / RTI &gt;
Wherein an outer circumferential portion of the first battery case surrounds an outer circumferential end portion of the second battery case at a portion where the first battery case and the second battery case are in contact with each other and a sealing folding portion is formed in the sealing folding portion, Wherein the battery case and the second battery case are welded to each other. The battery cell according to claim 1, wherein the electrode assembly is a folding structure, a stacking structure, a stacking / folding structure, or a lamination / stacking structure. The battery cell according to claim 1, wherein the first battery case is made of a metal material. The battery cell according to claim 1, wherein the first battery case comprises a metal plate, and the housing part is recessed corresponding to the shape of the electrode assembly. The battery cell according to claim 3, wherein the first battery case is made of aluminum or an aluminum alloy. The battery cell according to claim 3, wherein the inner surface of the first battery case is coated with an electrically insulating material. The battery cell according to claim 6, wherein the electrically insulating material is a polyolefin resin. The battery cell according to claim 1, wherein the second battery case is made of a laminate sheet including a resin outer layer, a barrier metal layer, and a heat-meltable resin sealant layer. The battery cell according to claim 1, wherein the second battery case is a planar sheet-like sheet structure. The battery cell according to claim 1, wherein the outer peripheral portion of the first battery case and the outer peripheral end of the second battery case are integrally joined by laser welding in the sealing folding portion. The battery cell according to claim 1, wherein the electrode terminals of the electrode assembly are protruded from one side or the other side of the first cell case and the second cell case. 12. The battery cell according to claim 11, wherein one side or the other side where the electrode terminals of the first battery case and the second battery case protrude is heated and pressed by a press to be adhered and sealed. . The battery cell according to claim 1, wherein in the sealing folding portion, the outer peripheral portion of the first battery case is bent so as to be in contact with the outer surface of the second battery case, which is the opposite surface of the storage portion. The battery cell according to claim 1, wherein the width of the sealing folding portion is 1% to 5% of the width of the second battery case. 15. The battery cell according to claim 14, wherein the width of the sealing folding portion is 1 mm to 2 mm. The battery cell according to claim 1, wherein the sealing folding portion has a rectangular or square shape in a vertical section. The battery cell according to claim 1, wherein the battery cell is a lithium secondary battery. A battery pack comprising at least two battery cells according to claim 1. A device according to claim 18, comprising the battery pack as a power source. 20. The device of claim 19, wherein the device is selected from a cell phone, a wearable electronic device, a portable computer, a smart pad, a netbook, a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, Lt; / RTI &gt;

Images