KR20170088024A - Pouch-typed Battery Cell Having Height Difference between Bent Sealing Portion and Electrode Assembly-receiving Part - Google Patents

Abstract

Provided is a battery cell with an excellent volume capacity by minimizing an increase in thickness due to bending of a sealing surplus part thereof. The battery cell comprises: a battery case including an anode, a separator, an electrode assembly with a cathode laminated structure, a storage part in which the electrode assembly is embedded, and sealing parts due to heat fusion in an outer periphery of the storage part. With respect to each of the sealing parts placed in both side surfaces on the basis of a position of an electrode terminal, a part of each of the sealing parts is vertically bent once toward the storage part, wherein the height on a vertical cross section of the each of the sealing parts is relatively smaller than the height on a vertical cross section of the storage part.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a pouch-type battery cell having a bending sealing portion and an electrode assembly receiving portion,

The present invention relates to a pouch-shaped battery cell in which a bending sealing portion and an electrode assembly receiving portion have a height difference.

As information technology (IT) technology has developed remarkably, various portable information and communication devices have been spreading, so that the 21st century is being developed into a "ubiquitous society" capable of providing high quality information services regardless of time and place.

As a development base for such a ubiquitous society, a lithium secondary battery occupies an important position. Specifically, the rechargeable lithium secondary battery is widely used as an energy source for wireless mobile devices, and is proposed as a solution for air pollution of existing gasoline vehicles and diesel vehicles using fossil fuels And also as an energy source for electric vehicles, hybrid electric vehicles, and the like.

As described above, as the devices to which the lithium secondary battery is applied are diversified, the lithium secondary battery has been diversified to provide an appropriate output and capacity for the applied device. In addition, miniaturization is strongly demanded.

The lithium secondary battery may be classified into a cylindrical battery cell, a prismatic battery cell, and a pouch-shaped battery cell depending on its shape. Among them, a pouch-type battery cell which can be stacked with a high degree of integration, has a high energy density per unit weight, and is inexpensive and easy to deform is attracting much attention.

Fig. 1 schematically shows a typical structure of a typical pouch-shaped battery cell.

1, the battery cell 10 includes an upper cell case 11 and a lower cell case 12, and an electrode assembly (not shown) is embedded in each of the battery cases 11 and 12 The receiving portions 13 are formed. The pouch-shaped battery cell 10 is formed by sealing the outer periphery of the pouch-shaped battery cell 10 with the electrode assembly embedded in the cell cases 11 and 12 to form the sealing pads 14, 14 are bent in the direction of the housing part 13 and brought into close contact with the housing part 13.

However, since the height H1 of the folded sealing pad 14 is larger than the height H2 of the receiving portion 13 and protrudes above the receiving portion 13, And the double folded sealing rings 14 cause a problem of decreasing the capacity of the battery cell 10 in terms of volume by increasing the thickness thereof.

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.

SUMMARY OF THE INVENTION An object of the present invention is to provide a battery cell having an excellent volume-to-volume capacity by minimizing an increase in thickness due to bending of a sealing surplus portion of the battery cell.

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

The battery case may include an electrode assembly having a positive electrode, a separator, and a negative electrode laminated structure, and a battery case having a housing portion in which the electrode assembly is embedded, and a sealing portion formed by heat fusion at the outer periphery of the housing portion.

Side sealing portions are vertically bent one time in the direction of the receiving portion, and the folding height on the vertical section of the side sealing portion is smaller than the height of the vertical section of the receiving portion And may have a relatively smaller structure than the height.

Therefore, in the battery cell according to the present invention, a part of the side sealing part is vertically bent once in the direction of the receiving part, and the bending height on the vertical section of the side sealing part is relatively smaller than the height on the vertical section of the receiving part It is possible to minimize the thickness increase due to the bending of the sealing surplus portion and to provide the battery cell with excellent volume-to-volume capacity.

In one embodiment of the present invention, the battery case may comprise a first case and a second case,

The housing part includes a first housing part having a part of the electrode assembly built in and formed on the first housing and a second housing part having a built-in remaining part of the electrode assembly and formed on the second housing Can be.

In one specific example, the height of the first receiving portion on the vertical section may be larger than the height of the second receiving portion on the vertical section.

The height of the first accommodating portion on the vertical section may be 110% to 400% of the height of the second accommodating portion on the vertical section. When the height of the vertical section of the first housing section exceeds 400% of the height of the vertical section of the second housing section, the volume of the first housing section and the volume of the second housing section differ greatly, Which may cause structural instability of the battery cell.

The side sealing portion may be vertically bent in the direction of the first receiving portion, and the side sealing portion may have a bending height on a vertical section relatively smaller than a height on a vertical section of the first receiving portion.

The bending height on the vertical section of the side sealing portion may be 50% to 90% of the height of the vertical section of the first receiving portion. When the bending height on the vertical section of the side sealing portion is less than 50% of the height of the vertical sectional surface of the first containing portion, the side sealing portion may be formed smaller than the receiving portion and the sealing force of the battery case may not be secured sufficiently. The electrolyte may leak when the internal pressure of the battery cell increases. On the other hand, when the bending height on the vertical section of the side sealing portion is more than 90% of the height of the vertical sectional surface of the first containing portion, the side sealing portion is further bent once more, It is possible to cause a problem that the volume of the cell is reduced.

In another embodiment of the present invention, the battery case may include an upper cover and a lower case, and the upper cover may be formed in a plate-like shape, and the housing portion may be formed on a lower case. In such a structure, the electrode assembly is embedded only in the housing part formed in the lower case, and the upper cover is mounted on the upper end of the built-in electrode assembly and can be sealed.

In one specific example, the side sealing portion may be vertically bent in the direction of the receiving portion of the lower case, and the side sealing portion may have a structure in which the bending height on the vertical section is relatively smaller than the height on the vertical section of the receiving portion of the lower case Lt; / RTI >

The bending height on the vertical section of the side sealing portion may be 50% to 90% of the height of the vertical section of the receiving portion of the lower case. When the bending height on the vertical cross section of the side sealing portion is less than 50% of the height of the vertical cross section of the receiving portion of the lower case, the side sealing portion is formed smaller than the receiving portion and the sealing force of the battery case may not be secured sufficiently , Which may lead to a problem of leakage of the electrolyte when the internal pressure of the battery cell increases. On the other hand, when the bending height on the vertical section of the side sealing portion is more than 90% of the height of the vertical cross section of the receiving portion of the lower case, the side sealing portion is further bent once more, It is possible to cause a problem that the volume of the cell is reduced.

According to another embodiment of the present invention, the side portion sealing portion may be cut by a size corresponding to the width of the lower side sealing portion in an end portion opposite to the electrode terminal in a state before being folded.

In addition, the lower sealing portion may be bent once in the direction of the receiving portion. In such a structure, in the process of bending the side sealing portion, the bottom sealing portion interlocks with the side sealing portion so as not to cause a structural change, so that the bending process of the side sealing portion and the bottom sealing portion can be sequentially and independently performed independently .

Like the side sealing portion, the lower sealing portion may have a structure in which the bending height on the vertical cross section is relatively smaller than the height on the vertical cross section of the receiving portion.

Specifically, the bending height on the vertical section of the lower sealing portion may be 50% to 90% of the height of the vertical section of the receiving portion. When the bending height on the vertical section of the lower sealing portion is less than 50% of the height of the vertical sectional surface of the receiving portion, the lower sealing portion may be formed smaller than the receiving portion so that the sealing force of the battery case may not be secured sufficiently, It is possible to cause a problem that the electrolyte leaks when the internal pressure increases. When the bending height on the vertical section of the lower sealing portion is more than 90% of the height of the vertical sectional surface of the receiving portion, the lower sealing portion must be bent one more time, so that the volume capacity of the battery cell is small Can cause problems.

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.

The battery case may include a pouch-shaped case having a laminate structure including a metal layer and a resin layer.

As a specific example of the battery case, the battery case is made of a laminate sheet including a resin outer layer of excellent durability, a metal layer of barrier property, and a heat-fusible resin sealant layer, and the resin sealant layers are heat- .

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 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 one battery cell.

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, in the both side sealing parts, a part of the side sealing part is horizontally bent in the direction of the receiving part to form the first bent part, and the remaining part is bent in the direction of the receiving part, And the sealing property of both side sealing portions of the battery is enhanced to suppress the occurrence of the swelling phenomenon and the bending phenomenon that may occur due to the increase in the internal pressure due to the degeneration of the battery due to repeated charging and discharging.

1 is a side view of a conventional pouch-shaped battery cell;
2 is a side view of a battery cell according to one embodiment of the present invention;
3 is a side view of a battery cell according to another embodiment of the present invention;
4 is a plan 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.

2 is a schematic side view of a battery cell according to an embodiment of the present invention.

Referring to FIG. 2, the battery cell 100 includes a first case 110, a second case 120, and an electrode assembly (not shown) embedded in the case 110, 120.

The first case 110 has a first housing part 111 in which a part of the electrode assembly is housed and a second housing part 121 in which the remaining part of the electrode assembly is housed is formed in the second case 120 .

The height H3 of the first receiving portion 111 is larger than the height H4 of the second receiving portion 121 on a vertical cross section.

The lateral side sealing portion 130 is vertically bent in the direction of the first receiving portion 111 and the folding height H5 of the side sealing portion 130 is perpendicular to the height H3 of the first receiving portion 111, And is relatively small in structure.

The folding height H5 of the side sealing portion 130 is 80% of the height H3 of the first receiving portion 111 on the vertical section.

3 is a schematic side view of a battery cell according to another embodiment of the present invention.

3, the battery cell 200 includes an upper cover 210, a lower case 220, and an electrode assembly (not shown) embedded in the lower case 220.

The upper case 210 is mounted on the upper end of the lower case 220 so that the battery cell 200 is sealed.

The lateral side sealing portion 230 is vertically bent in the direction of the receiving portion 221 and the folding height H6 of the side sealing portion 230 on the vertical cross section is relatively smaller than the height H7 of the receiving portion 221 Structure.

The bending height H6 of the side sealing portion 230 is 80% of the height H7 of the receiving portion 221 on the vertical section.

FIG. 4 schematically shows a plan view of a battery cell according to another embodiment of the present invention.

4, an end portion 331 of the side surface sealing portion 330 facing the electrode terminal 301 in a state before being bent (A) is cut to a size corresponding to the width W1 of the lower side sealing portion .

The lower side sealing portion 340 is bent once in the direction of the storage portion 311 in the state B in which the side sealing portion 330 is bent.

The remaining structure except for this structure is the same as the embodiment described with reference to FIG. 2, 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 (18)

A battery case having an electrode assembly having a positive electrode, a separator, and a negative electrode laminated structure, and a battery case having a housing portion in which the electrode assembly is embedded, and a sealing portion formed by heat fusion at an outer periphery of the housing portion;
Side sealing portions are vertically bent one time in the direction of the receiving portion, and the folding height on the vertical section of the side sealing portion is smaller than the height of the vertical section of the receiving portion And the height of the battery cell is smaller than a height of the battery cell. The method according to claim 1,
The battery case comprises a first case and a second case;
The housing part includes a first housing part having a part of the electrode assembly built in and formed on the first housing and a second housing part having a built-in remaining part of the electrode assembly and formed on the second housing And the battery cell. The battery cell according to claim 2, wherein the height of the first housing part on the vertical section is relatively larger than the height of the second housing part on the vertical section. The battery cell according to claim 3, wherein the height of the first housing part on the vertical section is 110% to 400% of the height of the second housing part on the vertical section. 4. The battery according to claim 3, wherein the side sealing portion is vertically bent in the direction of the first housing portion, and the side height sealing portion has a bending height on a vertical section that is relatively smaller than a height on a vertical section of the first housing portion. Cell. The battery cell according to claim 5, wherein a height of bending on a vertical section of the side sealing portion is 50% to 90% of a height of a vertical section of the first containing portion. The battery cell according to claim 1, wherein the battery case comprises an upper cover and a lower case, the upper cover is formed in a plate-like shape, and the housing part is formed on a lower case. [7] The seat according to claim 7, wherein the side sealing portion is vertically bent in the direction of the receiving portion of the lower case, and the side height sealing portion has a folding height on a vertical section smaller than a height on a vertical section of the receiving portion of the lower case . The battery cell according to claim 8, wherein a height of bending on a vertical section of the side sealing portion is 50% to 90% of a height of a vertical cross section of the receiving portion of the lower case. The battery cell according to claim 1, wherein the side sealing portion is cut off by a size corresponding to a width of the lower sealing portion, the end portion facing the electrode terminal in a state before being folded. 11. The battery cell according to claim 10, wherein the lower sealing portion is vertically bent once in the direction of the receiving portion. 12. The battery cell according to claim 11, wherein the lower sealing portion has a bending height on a vertical section that is relatively smaller than a height on a vertical section of the receiving portion. 13. The battery cell according to claim 12, wherein the bending height on the vertical section of the lower sealing portion is 50% to 90% of the height of the vertical section of the receiving portion. 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 battery case comprises 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 battery cell is a lithium secondary battery. A battery pack comprising at least one battery cell according to any one of claims 1 to 16. A device as claimed in claim 17 comprising a battery pack as a power source.

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