KR101717194B1 - Electrode Assembly of Incline Structure and Battery Cell Employed with the Same - Google Patents

Abstract

An electrode assembly having a structure in which a separator is interposed between a positive electrode and a negative electrode is embedded in a battery case, wherein at least two electrodes or unit cells are stacked in a height direction with respect to a plane, And a battery case in which a storage portion for mounting the battery case is formed; Wherein the electrode assembly has a rectangular shape having a side (a), a side (b), a side (c), and a side (d) in a planar shape, is inclined so that the internal angle between sides (b) adjacent to a) is less than 90 degrees; And the housing portion of the battery case is formed in an inner surface shape corresponding to the plane shape of the electrode assembly.

Description

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to an electrode assembly having an inclined structure and a battery cell including the electrode assembly.

More particularly, the present invention relates to a battery cell in which an electrode assembly having a separator interposed between an anode and a cathode is embedded in a battery case, wherein at least two electrodes or unit cells And a battery case having a housing part for mounting the electrode assembly, wherein the electrode assembly has a shape of a side, a side, a side, a side, c and sides d and inclined so that the internal angle between the side a where the electrode terminals of the electrode plates or unit cells are located and the side b adjacent to the side a is less than 90 degrees, And the housing portion of the battery case is formed in an inner surface shape corresponding to a plane shape of the electrode assembly.

Due to the development of technology and demand for mobile devices, the demand for secondary batteries is also rapidly increasing. Among them, lithium secondary batteries, which have high energy density, high operating voltage and excellent storage and life characteristics, It is widely used as an energy source.

The lithium secondary battery is classified into a cylindrical battery, a prismatic battery, a pouch-type battery, and the like depending on the outer shape thereof, and may be classified into a lithium ion battery, a lithium ion polymer battery, and a lithium polymer battery depending on the type of electrolyte.

Due to recent trend toward miniaturization of mobile devices, there is a growing demand for thin rectangular prismatic batteries and pouch-type cells, and particularly for pouch-type cells which are easy to deform in shape, low in manufacturing cost, Interest is high.

Generally, a pouch-type battery refers to a battery in which an electrode assembly and an electrolyte are sealed inside a pouch-shaped case of a laminate sheet composed of a resin layer and a metal layer. The electrode assembly housed in the battery case has a jelly-roll type (wound type), a stacked type (stacked type), or a composite type (stacked / folded type) structure.

FIG. 1 schematically shows a structure of a pouch-type secondary battery including a stacked electrode assembly.

1, the pouch-type secondary battery 10 includes an electrode assembly 30 including an anode, a cathode, and a solid electrolyte coating separator disposed between the anode and the cathode, And two electrode leads 40 and 41 electrically connected to the negative electrode tabs 31 and 32 are sealed to be exposed to the outside.

The battery case 20 is composed of a case body 21 including a concave shaped storage portion 23 on which the electrode assembly 30 can be seated and a cover 22 integrally connected to the body 21 have.

The battery case 20 is made of a laminate sheet and is composed of an outer resin layer 20a forming an outermost periphery, a barrier metal layer 20b for preventing penetration of a material, and an inner resin layer 20c for sealing .

In the stacked electrode assembly 30, a plurality of positive electrode tabs 31 and a plurality of negative electrode tabs 32 are fused to each other and coupled to the electrode leads 40 and 41. In addition, when the upper end portion 24 of the case body 21 and the upper end portion of the cover 22 are thermally fused by a heat welding machine (not shown), a short circuit occurs between the heat fusion welding machine and the electrode leads 40 and 41 An insulating film 50 is attached to the upper and lower surfaces of the electrode leads 40 and 41 in order to prevent the electrode leads 40 and 41 and ensure the sealing property between the electrode leads 40 and 41 and the battery case 20.

However, in recent years, a new type of battery cell is required due to a slim type or various design trends.

In addition, since the above-described battery cells include an electrode assembly having the same size or capacity, in order to obtain a novel structure considering the design of a device to which the battery cell is applied, it is necessary to reduce the capacity of the battery cell, There is a problem that the design of the device needs to be changed.

In addition, there is a problem that it is difficult to manufacture a battery cell satisfying a desired condition due to the complicated electrical connection method in the design change process.

Furthermore, there is a problem that the battery case must be manufactured according to the shape of the electrode assembly.

Accordingly, there is a high demand for an applicable electrode assembly, a battery case, and a battery cell including the same, depending on the shape of a device to which the battery cell is applied.

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.

More specifically, it is an object of the present invention to design a battery cell in a structure that can be mounted in various spaces of a device to maximize the utilization of the internal space of the device, and to move away from the external structure of a device having a generally rectangular structure, The present invention provides a battery cell that can be efficiently mounted even in a device having a battery.

According to an aspect of the present invention, there is provided a battery cell in which an electrode assembly having a separator interposed between an anode and a cathode is embedded in a battery case,

An electrode assembly in which two or more electrodes or unit cells are stacked in a height direction with respect to a plane, and a battery case having a housing portion for mounting the electrode assembly;

Wherein the electrode assembly has a rectangular shape having a side (a), a side (b), a side (c), and a side (d) in a planar shape, is inclined so that the internal angle between sides (b) adjacent to a) is less than 90 degrees;

The housing portion of the battery case is formed in an inner surface shape corresponding to the plane shape of the electrode assembly.

Therefore, the battery cell according to the present invention can be manufactured as a battery cell having various capacities and sizes based on the specific structure as described above. In the manufacture of the device for mounting the battery cell, It is possible to maximize the utilization of the space inside the device.

In one specific example, the unit cell has a structure in which one or more positive electrodes and one or more negative electrodes are stacked with a separator interposed therebetween, and the type of electrodes disposed on both sides, It may be another pool cell.

The electrode plates or the unit cells may have a structure in which the electrode terminals are stacked so as to be arranged on the upper or lower side or the electrode terminals are arranged in the upper side and the first electrode terminal is arranged, And two electrode terminals are stacked so as to be arranged.

The arrangement of the electrode terminals of the unit cells is not particularly limited. For example, the first electrode terminal may be a positive electrode terminal and the second electrode terminal may be a negative electrode terminal.

As described above, the battery cell according to the present invention is a square having a side (a), a side (b), a side (c) and a side (d) in a planar shape, And an internal angle between the side (a) where the electrode (a) is located and the side (b) adjacent to the side (a) is less than 90 degrees. The internal angle between the sides a and b may be in the range of 20 to 89 degrees, more specifically in the range of 30 to 85 degrees, particularly in the range of 40 to 80 degrees.

In a specific example, sides a and sides c are parallel to each other, and / or sides b and sides d are parallel to each other. For example, it may be a plane parallelogram or rhombic structure.

However, it goes without saying that the above examples are only a few examples.

The battery cell may be, for example, a pouch-type battery cell in which an electrode assembly is embedded in a pouch-shaped case, but is not limited thereto.

More specifically, the pouch-shaped battery cell includes a pouch-shaped case of a laminate sheet including a resin layer and a metal layer, for example, an aluminum laminate sheet. The pouch-shaped battery cell includes an electrode assembly, . ≪ / RTI >

The battery case is made to have a thickness with a predetermined flexibility in which the housing portion can be formed. If the thickness of the battery case is too thick, there is a risk of breakage due to lack of flexibility in the process of forming the housing portion, and the volume and weight of the battery cell itself increases. Conversely, There arises a problem that the battery case easily breaks due to the heat generated by the battery. Therefore, it is preferable that the battery case is made to have a thickness of 50 to 200 [mu] m with appropriate flexibility and durability.

The upper case and the lower case constituting the battery case may be independent members or substantially one member to which one end is connected.

The outer shape of the battery case may be formed by various methods.

In one specific example, the housing portion can be formed by drawing the battery case in the same shape as the shape of the electrode assembly in which the internal angle between sides a and sides b is less than 90 degrees.

In another specific example, the battery case may be drawn in the shape of an electrode assembly having an internal angle of 90 degrees between the sides a and sides b to form a receiving portion.

In the latter case, for example, the electrode assembly in which the electrodes or the unit cells according to the present invention are stacked is inserted into the housing part of the battery case, and a vacuum is applied inside the housing part to shrink the housing part to correspond to the electrode assembly The outer shape of the battery case can be formed. Since the electrode assembly has a structure in which equilateral quadrangular or rhomboidal electrodes or unit cells are stacked, the electrode assembly may be formed in such a manner that the angle between the sides (a) and (b) The battery case is deformed while being shrunk in accordance with the outer shape of the electrode assembly when a vacuum is applied to the receiving portion.

This vacuum application method can solve the problem of manufacturing a new battery case every time the design of the electrode assembly is changed, and can suppress the local concentration of the stress.

Specifically, the receiving portion of the battery case may have a rectangular parallelepiped shape including a flat portion corresponding to an upper end size of the electrode assembly in a state before vacuum application. In this case, the rectangular parallelepiped shape of the receiving portion is deformed into an inner shape corresponding to the plane shape of the electrode assembly.

The battery cell may be a lithium ion battery or a lithium ion polymer battery cell, but is not limited thereto.

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 device comprising the battery cell as a power source, wherein the device is used in a mobile phone, a portable computer, a smart phone, a tablet PC, a smart pad, a netbook, a LEV (Light Electronic Vehicle) A hybrid electric vehicle, a plug-in hybrid electric vehicle, and a power storage device.

The present invention also provides a battery pack including at least two battery cells as unit cells. That is, the present invention provides a battery pack having a structure in which two or more battery cells are connected in series and / or in parallel as a unit cell, and the battery pack is used for a mobile phone, a portable computer, a smart phone, a tablet PC, a smart pad, (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, the battery cell according to the present invention can easily secure the mounting space of the battery cells in the device due to the deformed shape, maximize the utilization of the space inside the device, And it is possible to further miniaturize the device. Moreover, due to the structure of the electrode assembly, the battery case, and the like, a desired battery cell can be easily manufactured despite the change of design.

1 is a perspective view of a conventional battery cell;
Figure 2 is a top view of electrodes according to one embodiment of the present invention;
3 is a perspective view of an electrode assembly according to one embodiment of the present invention;
4 is a schematic view illustrating a process of housing the electrode assembly according to the present invention in a battery case having a storage portion;
5 and 6 are schematic diagrams illustrating a process of deforming the housing portion of the battery case;

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. 2 is a plan view of electrodes according to one embodiment of the present invention, and FIG. 3 is a perspective view of an electrode assembly according to an embodiment of the present invention.

Referring to these drawings, an electrode assembly 100 according to the present invention includes two or more electrodes stacked in a height direction with respect to a plane, and the electrodes are formed in a planar shape as a side a, side b, side c And the side A where the electrode terminals 110 and 120 of the electrode plates are located and the side b adjacent to the side a are about 70 degrees, It is.

The positive electrode plate and the negative electrode plate are stacked with a separator interposed therebetween. The electrode plates 110 and 120 are arranged in the upper side (a) Respectively.

Therefore, the electrode assembly 100 according to the present invention is stacked in the height direction, and the electrode assembly 100 is housed in the pouch-shaped battery case and then sealed to complete the battery cell.

FIG. 4 is a schematic view showing a process of accommodating the electrode assembly according to the present invention in a battery case having a storage portion, and FIGS. 5 to 6 are diagrams illustrating a process of deforming the storage portion of the battery case.

4, the electrode assembly 100 according to the present invention is mounted on the housing part 150 of the battery case 160, and then the battery case 160 is folded in half and the number of the battery case 160 The outer peripheral surface 140 of the battery case is thermally fused and sealed by the electrode assembly 100 mounted on the lead 150. [

5 and 6, the housing part 150 of the battery case 200 is formed in a rectangular parallelepiped shape including a flat portion corresponding to the upper size of the electrode assembly, So that a surplus space between the storage part 150 of the battery case 200 and the electrode assembly 100 is removed.

When the vacuum is applied, the accommodating portion 150 is brought into close contact with the outer surface of the electrode assembly 100 having a balanced quadrangular shape, and the accommodating portion 170 is formed in a shape corresponding to the outer shape of the electrode assembly.

In some cases, the shape of the accommodating portion in FIG. 4 may be made to conform to the outer shape of the electrode assembly, and in this case, a step of applying a vacuum may not be performed.

As shown in FIGS. 2 to 6, the battery cell 200 according to the present invention can be manufactured as a battery cell having various capacities and sizes, and can easily be mounted to a space in which a conventional battery cell is difficult to mount Since the battery cell having a larger capacity can be mounted in a limited space according to the internal structure of the device, utilization of the space inside the device can be maximized.

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

Claims (17)

A battery cell in which an electrode assembly having a separator interposed between an anode and a cathode is embedded in a battery case,
An electrode assembly in which two or more unit cells are laminated in a height direction with respect to a plane, and a battery case having a storage portion for mounting the electrode assembly;
The electrode assembly has a rectangular shape having a side (a), a side (b), a side (c), and a side (d) in a planar shape and has a side (a) The interior angle between adjacent sides b is less than 90 degrees;
The housing portion of the battery case is formed in an inner surface shape corresponding to a plane shape of the electrode assembly;
Wherein the battery case is formed by deforming the battery case so as to correspond to an outer shape of the electrode assembly by applying a vacuum to the inside of the battery case, and prior to the application of the vacuum, the housing portion of the battery case has a rectangular parallelepiped shape,
Wherein the internal angle between the sides a and b is in the range of 20 to 89 degrees and the sides a and c are parallel to each other and the sides b and d are parallel to each other ,
The unit cell includes a bi-cell having the same type of electrodes located at both ends or a pull cell having different types of electrodes located at both ends in a structure in which one or more positive electrode plates and one or more negative electrode plates are stacked with a separator interposed therebetween ,
Wherein the unit cells are in a plane parallelogram shape. delete The battery cell according to claim 1, wherein the unit cells are stacked so that the electrode terminals are arranged on the upper or lower side. The battery cell according to claim 1, wherein the unit cells are stacked such that first electrode terminals are arranged on the upper side of the electrode terminals, and second electrode terminals are arranged on the lower side opposite to the upper side. The battery cell according to claim 4, wherein the first electrode terminal is a positive electrode terminal, and the second electrode terminal is a negative electrode terminal. delete delete delete delete The battery cell according to claim 1, wherein the battery case comprises a laminate sheet of a metal layer and a resin layer. The battery cell according to claim 10, wherein the laminate sheet is an aluminum laminate sheet. The battery cell according to claim 1, wherein the thickness of the battery case is 50 to 200 占 퐉. delete The battery cell according to claim 1, wherein the battery cell is a lithium ion battery cell or a lithium ion polymer battery cell. A battery pack comprising at least two battery cells according to any one of claims 1, 3 to 5, 10 to 12, and 14 as unit cells. A device comprising a battery cell according to any one of claims 1, 3 to 5, 10 to 12, and 14 as a power source. A device comprising the battery pack according to claim 15 as a power source.

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