KR20170091938A - Secondary Battery Cell Case Having Round Edge and Apparatus for Manufacturing the Same - Google Patents

Abstract

The present invention provides a battery cell case and an apparatus for manufacturing the same. The present invention relates to a pouch-type battery cell case made of a laminate sheet. The pouch-type battery cell case includes an accommodating part for accommodating an electrode assembly and an electrolyte. The accommodating part includes a base part having an upper surface on which the electrode assembly is mounted, sidewalls surrounding the side surfaces of the electrode assembly, and lower edges connecting the base part and the sidewalls and having curved surfaces. The radius of curvature (R) of at least one of the lower edges is 0.8 mm to 1.5 mm. The safety of a battery can be ensured.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery cell case having a curved edge,

The present invention relates to a battery cell case having a curved edge and an apparatus for manufacturing the same, and more particularly, to a battery cell case in which a curvature radius of a bottom edge of a battery cell case, .

As technology development and demand for mobile devices have increased, the demand for secondary batteries as energy sources is rapidly increasing. In recent years, the use of secondary batteries as a power source for electric vehicles (EV) and hybrid electric vehicles (HEV) Among such secondary batteries, there is a high demand for a lithium secondary battery having a high energy density, a high discharge voltage and an output stability.

Such a lithium secondary battery mainly uses a lithium-based oxide as a positive electrode active material and a carbonaceous material as a negative electrode active material. The lithium secondary battery is manufactured in various shapes. Typical shapes include a cylindrical shape, a square shape, and a pouch shape.

Double pouch type secondary batteries are widely used because of the possibility of secondary battery deformation and high energy density. The pouch type secondary battery includes an electrode assembly and a pouch case that receives and seals the electrode assembly.

The electrode assembly includes a negative electrode to which the negative electrode active material is applied to the negative electrode collector, a positive electrode to which the positive electrode active material is applied, and a separator interposed between the negative electrode and the positive electrode. The separation membrane is a solid-type membrane made of a polymer. In addition to the function of insulating the anode and the cathode, the separation membrane enables the lithium ion to move between the anode and the cathode.

The pouch case includes a lower case defining a receiving space for the electrode assembly, and an upper case having four ends connected to the four ends of the lower case. Here, the lower case is usually formed into a shape having the accommodating portion of the electrode assembly inside thereof by deep drawing molding, and the joints between the four ends of the upper and lower cases are usually formed by thermal bonding.

Fig. 1 is a perspective view of a battery cell case, Fig. 2 is a process drawing showing a manufacturing process of a first case including such a storage portion, Fig. 3 is a view corresponding to the processes (c) Sectional view of a conventional storage portion manufacturing process is shown as an example, and Fig. 4 schematically shows an enlarged view of a portion A including the edges of the first case of Fig.

1, a case of a pouch-shaped battery cell 10 formed of a laminate sheet includes a first case 20 including a concave shaped housing portion 21 for housing an electrode assembly, And a second case 30 connected to one end of the housing 30 to seal the receiving portion. 1 shows a configuration in which the second case 30 is connected to one side of the first case 20, the second case 30 may be separate from the first case 20 to be.

The accommodating portion 21 of the first case 20 has a substantially rectangular parallelepiped shape and includes a base portion 22 on which the electrode assembly is mounted and side walls 23 surrounding side surfaces of the electrode assembly. And bottom edges 24 connecting the side walls 23.

The first case 20 further includes a sealing portion 25 extending from the receiving portion 21 and a top edge 26 connecting the receiving portion 21 and the sealing portion 25 have.

Referring to FIGS. 2 to 4, as described above, the first case 20 forms a receiving portion 21 which houses an electrode assembly on the inner side by deep drawing molding.

The deep draw forming is performed by forming a die jig 40 in which a laminate sheet is mounted on the open upper portion of the indentation portion 41 for forming a deep drawing, And a punching jig 50 inserted into the indentation of the jig to deform the laminate sheet to perform a deep drawing process.

Specifically, as shown in Fig. 2, a laminate sheet 20 'is mounted on the die jig 40 on which the indentation 41 is formed (steps (a) and (b)), The receiving portion 21 is formed by inserting the punching jig 50 into the indentation portion 41 to deform the laminate sheet 20 'to correspond to the shape of the indentation portion and removing the punching jig 50 (Step (c) And (d).

3 and 4, the edge 42 of the die jig 40 corresponds to a portion where the laminate sheet 20 'is deformed into the upper edges 26 of the receiving portion 21, And the curvature radii R1 and R2 of the corner 51 corresponding to the portions where the laminate sheet 20 'is deformed into the lower edges 24 of the receiving portion 21 in the punching jig 50 to about 0.75 mm The lower edges 24 and the upper edges 26 of the receiving portion 21 of the first case 20 having the deep drawing formed therein also have curvature radii R1 'and R2' of approximately 0.75 mm, At this time, the thickness t2 of the laminate sheet corresponding to the edges 24, 26 is thinner than 70% of the thickness t1 of the laminate sheet corresponding to the base 22.

Therefore, since the strength of the edges, particularly, the lower edges that do not bond to the second case is relatively weak and the possibility of deformation is high, problems such as cracks and ruptures easily occur due to an external impact and the like, Or the leakage can not be prevented, and the electrode assembly is pushed or deformed into the ruptured portion, thus degrading the safety of the battery.

Therefore, there is a need to develop a pouch case that can solve the safety problem due to the above-described molding by a simpler method.

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 It is an object of the present invention to solve the problem of increasing the radius of curvature of the lower edges of the housing part and reducing the thickness of the corresponding laminate sheet during the molding process for manufacturing the pouch-shaped battery cell case made of a laminate sheet. And to provide a case for a secondary battery capable of ensuring battery safety by a simple method.

According to an aspect of the present invention, there is provided a pouch-shaped battery cell case,

1. A pouch-type battery cell case made of a laminate sheet,

And an accommodating portion for accommodating the electrode assembly and the electrolyte;

The housing portion includes a base portion on which the electrode assembly is mounted on an upper surface, side walls surrounding side surfaces of the electrode assembly, and lower edges connecting the base portion and the side walls and having curved surfaces;

And a radius of curvature R of at least one of the lower edges is 0.8 mm to 1.5 mm.

In the case where the curvature radius of the edges is increased as in the present invention, the reduction rate of the thickness of the laminate sheet due to the deep drawing forming process for manufacturing the housing portion of the case is reduced. The thickness of the laminate sheet is thinner than other portions It is possible to minimize the thickness reduction of the lower edges that are vulnerable to external impact, thereby ensuring battery safety.

The relationship between this radius of curvature and the reduction in the thickness of the laminate sheet due to the deep drawing forming will be discussed in more detail later in the description of the apparatus for manufacturing the battery cell case according to the present invention.

For this reason, the lower edges preferably have a radius of curvature of 0.8 mm to 1.5 mm, and more specifically, 1 mm to 1.5 mm.

When the radius of curvature is less than 0.8 mm, the thickness of the laminate sheet corresponding to the lower edges becomes thinner than 70% of the thickness of the laminate sheet corresponding to the base portion, It is difficult to prevent the inflow or outflow of the electrolyte and water due to the occurrence of problems such as cracks and rupture due to external impact or the like and thus the electrode assembly is pushed or deformed to the ruptured portion and the cell stability is lowered If it is excessively larger than 1.5 mm, the dead space increases with the increase of the radius of curvature, and accordingly the volume-to-volume ratio may be reduced.

The battery cell case according to the present invention further includes a sealing portion extending from an outer periphery of the housing portion and upper edges having a curved surface connecting the sealing portion to the side walls of the housing portion; The radius of curvature of at least one of the top edges may be 0.3 mm to 1.0 mm in a range that is less than the radius of curvature R 'of the adjacent bottom edge.

As described above, when the radius of curvature is large, the thickness reduction ratio due to the deep drawing molding is reduced. However, since the shape difference from the rectangular electrode assembly is generally increased to increase the dead space in the receiving portion, There is a problem that the capacity relative to the total volume is decreased because the width of the sealing portion is relatively increased. Therefore, the upper edges, which are the portions to which the second case for sealing the case to be coupled with the first case are joined, can have a predetermined strength by bonding with the second case, and can be formed by increasing the radius of curvature It is desirable to configure the radius of curvature to be smaller than the radius of curvature of the adjacent lower edges in order to minimize the increase of the dead space and maximize the capacity.

For this reason, it is preferable that the upper edges are all 0.3 mm to 1.0 mm in the range where the radius of curvature is smaller than the radius of curvature of the adjacent lower edge, and more specifically, 0.5 mm to 0.5 mm in the range smaller than the radius of curvature of the adjacent edge. 0.8 mm.

If the radius of curvature is less than 0.3 mm, the thickness of the laminate sheet of the upper edges becomes very thin by deep draw forming, and is too weak for external impacts. If the radius is too large, As described above, the dead space increases with the increase of the radius of curvature, and thus the volume-to-volume ratio can be reduced.

With this radius of curvature, the rate of change in thickness of the laminate sheet can be expected as described above. Specifically, in the case of performing the deep drawing forming for the housing portion so as to have the radius of curvature, if the housing portion is formed at the same depth, the degree of drawing of the laminate sheet decreases as the radius of curvature becomes larger and as the radius of curvature decreases, the degree of drawing of the laminate sheet increases The radius of curvature of the back surface affects the extent to which the laminate sheet is stretched. Further, the thickness of the laminate sheet varies depending on the degree of stretching of the laminate sheet.

Therefore, taking these points into consideration, the thickness of the laminate sheet varies depending on the radius of curvature. Specifically, when the radius of curvature increases, the degree of elongation of the laminate sheet is small and the rate of change in thickness is small. And the rate of change in thickness becomes large and thin.

In detail, the thickness of the laminate sheet at the lower edges with the radius of curvature in the range of 0.8 mm to 1.5 mm is 70-100% of the thickness of the laminate sheet of the base, and the upper edges of the radius of curvature are in the range of 0.3 mm to 1.0 mm The thickness of the laminate sheet may be 50 to 80% of the thickness of the laminate sheet of the base.

The thickness of the laminate sheet corresponds to the radius of curvature. However, when the radius of curvature satisfies the above range, the thickness of the laminate sheet corresponding to the thickness of the laminate sheet satisfies the above range. . Therefore, the depth of the receiving portion can also be determined within a range that satisfies the above conditions.

When the thickness of the laminate sheet at the lower edges is less than 70% of the thickness of the laminate sheet at the bottom edge, the laminate sheet corresponding to the lower edges is weak and the possibility of deformation is large. Problems such as cracks and rupture easily occur due to an external impact or the like, so that the inflow or outflow of the electrolytic solution and water can not be prevented, and the electrode assembly is pushed or deformed into the ruptured portion, which lowers the safety of the battery. If the thickness of the laminate sheet at the upper edges is less than 50% of the thickness of the laminate sheet at the upper edges, the thickness of the laminate sheet corresponding to the lower edges is less than 70% There is a problem in that it can act as a weak part of the case and cause the above-mentioned problems.

On the other hand, when the thickness of the laminate sheet at the upper edges exceeds 80% of the thickness of the laminate sheet of the base portion, it means that the radius of curvature is increased, which is not preferable because the radius of curvature increases.

Generally, the battery cell contains a small amount of water generated or introduced during the manufacturing process of the battery, and in the case of a case made of a laminate sheet, moisture can permeate from the outside through a crack or a ruptured portion. Such moisture reacts with the lithium salt or the electrode active material in the electrolyte in the battery, thereby deteriorating the battery performance. In particular, HF is generated, which causes serious problems in high temperature safety.

For example, if it contains LiPF ₆ lithium salt in the electrolyte, LiPF ₆ is Li ⁺ and PF ₆ ^- should be present in ionic form, but the intention is the side reaction arose unstable PF ₅ is produced as a by-product unlike which And reacts with H ₂ O present in a trace amount in the electrolyte to form HF. HF destroys the SEI layer, causing dissolution of the anode, and this phenomenon occurs more prominently at high temperatures. HF, HCl, HBr, HI and the like are generated in addition to HF depending on the type of lithium salt used as the electrolyte, which can act as an acid as HF.

Further, when the electrolyte is depleted for the same reason as the side reaction of the electrolyte solution, there is a limitation in the movement of lithium, and the life characteristic of the secondary battery is remarkably deteriorated.

Furthermore, when a part of the case ruptures due to an external impact, the internal electrode assembly is severely deformed, and the electrode assembly is liable to be ignited by deformation of the electrode assembly, so that the safety is seriously affected.

The inventors of the present application have confirmed that it is very important to prevent the lower edges of the receiving portion, which are generated due to the deep drawing forming of the laminated sheet, from becoming weak portions, thus completing the present invention.

That is, the battery cell case according to the present invention is configured so that the thickness of the laminate sheet corresponding to the lower edges of the storage portion for storing the electrode assembly after the deep drawing forming process of the laminate sheet is not made too thin, It is possible to prevent cracks or ruptures due to an external impact and prevent the loss of electrolytic solution and the penetration of moisture and to prevent the electrode assembly from being pushed or deformed by the ruptured portion It is possible to prevent the occurrence of the ignition and ensure the safety.

The battery cell case may include a first case including the accommodating portion, a second case connected to one end of the first case to seal the accommodating portion, or a second case that is independent of the first case, And a second case to which the first case is attached. That is, the second case is not limited to the form as long as it is connected to the first case as shown in FIG. 1, or the case where the electrode assembly is sealed by the first case and the second case, No.

The housing may be formed in a size corresponding to the electrode assembly on one side of the case and may be formed on both sides of the case. Thus, in one example, the second case may have a flat structure without a housing portion, In another example, the second case may be configured to include the receiving portion in a form similar to that of the first case, but may be a flat structure without the receiving portion in order to simplify and improve the manufacturing process.

The laminate sheet constituting the case is, in detail, a three-layer structure including an outer coating layer made of a weather-resistant polymer, an inner sealant layer made of a heat-sealable polymer, and a barrier layer interposed between the outer coating layer and the inner sealant layer. .

Here, the outer coating layer is made of a weather resistant polymer having a tensile strength and a weather resistance higher than a predetermined level, and the weather resistant polymer may be polyethylene terephthalate (PET), polyethylene naphthalate (PEN) or nylon .

The barrier layer may be a metal layer in one specific example so as to exhibit a function of improving the strength of the case in addition to the function of preventing the inflow or outflow of foreign matter such as gas or moisture, But are not limited to, one selected from the group consisting of aluminum, iron, copper, tin, nickel, cobalt, silver, stainless steel, and titanium.

Wherein the inner sealant layer is made of a heat-sealable polymer having a low heat-sealability (thermal adhesiveness) and low hygroscopicity so as to suppress the penetration of an electrolytic solution and which is not expanded or eroded by an electrolytic solution, It may be a polyolefin, and more preferably, it may be an unoriented polypropylene (cPP).

The present invention is also an apparatus for manufacturing the battery cell case according to the present invention by deep drawing molding,

A die jig having a depressed portion of a shape corresponding to the accommodating portion formed on an upper surface thereof and having a laminate sheet mounted on an open upper portion of the depressed portion for forming a deep drawing; And

A punching jig inserted into the indented portion of the die jig to form a receiving portion by deformation of the laminate sheet;

And,

Wherein the curvature radius r of at least one corner among the corners corresponding to the portions where the laminate sheet is deformed into the lower edges of the accommodating portion in the punching jig is 0.8 mm to 1.5 mm. Lt; / RTI >

As described above, the receiving portion of the pouch-shaped battery cell case is formed by deep drawing molding. In order to make the curvature radius R of at least one of the lower edges of the receiving portion 0.8 mm to 1.5 mm, The radius of curvature r of the portion corresponding to the portion to be deformed into the lower edges of the receiving portion in the jig for performing molding must have the radius of curvature.

Here, in the deep drawing process of the laminate sheet, since the punching jig determines the shape of the lower edge by directly contacting the portion of the laminate sheet to be deformed by the lower edges of the receiving portion, The radius of curvature of the corners corresponding to the portion to be deformed into the lower edges may be between 0.8 mm and 1.5 mm, and more specifically between 1.0 mm and 1.5 mm. In this case, it is more preferable that all of the lower edges have the radius of curvature. It is preferable that the radius of curvature of all four corners of the lower surface that directly contacts the laminate sheet in the punching jig is 0.8 mm to 1.5 mm, 1.5 mm.

Similarly, in order to make the radius of curvature R of at least one of the upper edges of the receiving portion 0.3 mm to 1.0 mm, it is preferable that the portion to be deformed to the upper edges of the receiving portion in the jig for performing the deep- The radius of curvature r 'of the corresponding portion must have the radius of curvature.

Here, in the deep drawing process of the laminate sheet, the shape of the upper edge directly contacting the portion of the laminate sheet to be deformed by the upper edges of the receiving portion is determined by the die jig, so that the laminate sheet of the die- The radius of curvature of the corners corresponding to the portion to be deformed to the upper edges may be 0.3 mm to 1.0 mm, and more specifically 0.5 mm to 0.8 mm. It is more preferable that all of the upper edges have the radius of curvature. It is preferable that the radius of curvature of the four corners of the upper surface which directly contact the laminate sheet in the die jig is 0.3 mm to 1.0 mm, 0.8 mm.

As described above, the radius of curvature is related to the thickness change rate of the laminate sheet in accordance with the deep drawing forming. Specifically, the thickness of the laminate sheet corresponding to the portion deformed by the edges after the deep drawing molding varies depending on the radius of curvature of the sheet. Specifically, the greater the radius of curvature of the sheet, the smaller the difference in thickness before and after the deep-drawing forming of the laminate sheet.

For this reason, as described above, the thickness t of the laminate sheet corresponding to the portion deformed by the lower edges after the deep drawing molding may be 70 to 100% of the thickness t0 of the laminate sheet before the deep drawing molding And the thickness t of the laminate sheet corresponding to the portion deformed by the upper edges after the deep drawing molding may be 50 to 80% of the thickness t0 of the laminate sheet before the deep drawing molding.

The present invention also relates to the battery cell case. An electrode assembly including a cathode, a cathode, and a separator interposed between the anode and the cathode; And the electrolyte. The battery cell is not particularly limited. Specifically, the battery cell may be a so-called lithium secondary battery in which an electrolyte solution containing a lithium salt is impregnated into the electrode assembly.

The electrode assembly is composed of an anode and a cathode so that charging and discharging can be performed. For example, a structure in which an anode and a cathode are stacked with a separator interposed therebetween may be a folding (jelly-roll) Folding type.

The anode is prepared by applying a mixture of a cathode active material, a conductive material and a binder on a cathode current collector, followed by drying and pressing. If necessary, 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 changes in the battery. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon, aluminum or stainless steel A surface 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 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); A lithium manganese composite oxide having a spinel structure represented by LiNi _x Mn _2-x O ₄ ; 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 prepared by coating, drying and pressing the negative electrode active material on the negative electrode current collector, and may optionally further include a conductive material, a binder, a filler, and the like as described above.

The negative electrode current 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 electrical conductivity without causing chemical changes in the battery, and examples of the anode current collector include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, a 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 < 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 binder, the conductive material, and the filler added as necessary are the same as those in the anode.

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 electrolyte may be a non-aqueous electrolyte containing a lithium salt. The non-aqueous electrolyte containing the lithium salt is composed of a non-aqueous electrolyte and a lithium salt. Non-aqueous organic solvents, organic solid electrolytes, inorganic solid electrolytes, But is not limited thereto.

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

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

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

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

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

In one specific _{example, LiPF 6, LiClO 4, LiBF} 4, LiN (SO 2 CF 3) 2 , such as a lithium salt, a highly dielectric solvent of DEC, DMC or EMC Fig solvent cyclic carbonate and a low viscosity of the EC or PC of To a mixed solvent of linear carbonate to prepare a nonaqueous electrolyte solution containing a lithium salt.

The present invention provides a battery module including the battery cell, a battery pack including the battery module, and further provides a device including the battery pack.

The device may be, but is not limited to, a mobile electronic device, a power tool powered by an electric motor, An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; And a power storage system, but the present invention is not limited thereto.

The structure and manufacturing method of such a device are well known in the art, so a detailed description thereof will be omitted herein.

As described above, in the battery cell case according to the present invention, when the deep drawing forming process for forming the accommodating portion is formed, the radius of curvature of the edge portions of the lower edges of the accommodating portion, By increasing the radius of curvature of the edges, it is possible to prevent the thickness of the laminate sheet corresponding to the edges from being significantly thinned by a very simple method and to prevent the loss of electrolyte and the infiltration of water due to cracks or ruptures due to external impacts And the safety of the battery can be secured without the problem that the electrode assembly is pushed to the ruptured portion or deformed.

At the same time, the battery cell case according to the present invention minimizes the decrease in capacitance by preventing the increase of the dead space caused by increasing the radius of curvature by maintaining the radius of curvature of the upper edges having relatively high strength There is an effect.

1 is a perspective view of a pouch case;
2 is a process drawing showing a manufacturing process of a first case including a housing portion;
3 is a cross-sectional view illustrating a process of manufacturing a storage portion of a conventional first case corresponding to the processes (c) and (d) of FIG. 2;
4 is an enlarged view of a portion A including the edges of Fig. 3;
5 is a cross-sectional view illustrating a process of manufacturing a storage portion of a first case according to one embodiment of the present invention corresponding to the processes (c) and (d) of FIG. 2;
Fig. 6 is an enlarged view of a portion B including the edges of Fig. 5;

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.

1, the pouch-shaped battery cell case made of a laminate sheet includes a first case including a recessed recessed portion for receiving the electrode assembly, a second case connected to the first case and sealing the recessed case, The first case including a bottom portion having a bottom portion on which the electrode assembly is mounted, side walls surrounding side surfaces of the electrode assembly, and bottom edges having a curved surface connecting the bottom and sidewalls of the receiving portion; Seals extending from the receiving portion; And a top edge having a curved surface connecting the side wall of the receiving part and the sealing part.

2, the manufacturing process of the receiving portion due to the deep drawing forming is performed by mounting a laminate sheet on the die jig on which the indent portion is formed (Steps (a) and (b)), And the punching jig is removed by deforming the laminate sheet so as to correspond to the shape of the indentation (steps (c) and (d)).

The structure of the case and the manufacturing process of the housing part according to the present invention have been described in detail with reference to FIGS. 1 and 2. Hereinafter, according to one embodiment of the present invention, which is different from the conventional battery cell case shown in FIGS. The present invention will be described with reference to a process of manufacturing a first case including a housing portion having a structure in which a radius of curvature of lower edges of a battery cell case is increased and an enlarged view of lower edge portions of the first case formed therefrom.

5 and 6 are a cross-sectional view illustrating a manufacturing process of the storage part 121 of the first case 120 according to one embodiment of the present invention corresponding to the processes (c) and (d) of FIG. 2, Here, a schematic view showing an enlarged view of a portion B including the edges 124 and 126 is provided.

Referring to FIGS. 5 and 6, a first case 120 according to the present invention forms a receiving portion 121 that houses an electrode assembly on the inner side by deep drawing molding.

In the deep drawing molding, the laminate sheet is mounted on the die jig 140, and the punching jig 150 is inserted into the indentation 141 of the die jig 140 and removed to remove the laminate sheet into the shape of the indentation 141 By forming the accommodating portion 121 in such a manner as to correspond to each other.

At this time, the curvature radius r 'of the edge 142 corresponding to the portion where the laminate sheet is deformed into the upper edges 126 of the receiving portion 121 in the die jig 140 is in the range of 0.3 mm to 1.0 mm And the curvature radius r of the edge 151 corresponding to the portion where the laminate sheet is deformed into the lower edges 124 of the accommodating portion 121 in the punching jig 150 has a range of 0.8 mm to 1.5 mm The curvature radii R of the lower edges 124 and the upper edges 126 of the first case 120 also have the above ranges respectively after the deep drawing process.

This is because the upper edges 126 may have a predetermined strength relative to the lower edges 124 while being bonded to the first case and the second case sealing the case, While keeping the radius of curvature r 'similar to conventional to minimize the increase of the dead space and the increase of the seal width and to maximize the capacity, the lower edges 124, which are substantially weaker at the time of external impact, (r) to prevent cracks or ruptures by preventing the thickness from becoming very thin.

The curvature radii r and r 'of the jigs 140 and 150 influence the extent to which the laminate sheet is stretched. Specifically, as the radius of curvature r increases, the degree of stretch of the laminate sheet Is reduced.

The radius of curvature r of the punching jig 150 may be set to a value between 0.8 mm and 1.5 mm so that the thickness t of the laminate sheet corresponding to the lower edges 124 is set to a value The lower edges 124 can be prevented from becoming too thin, and the radius of curvature r 'of the die jig 140 can be adjusted from 0.3 mm to 1.0 mm The thickness t 'of the laminate sheet corresponding to the upper edges 126 can be adjusted to 50 to 80% of the thickness t0 of the laminate sheet before the deep drawing molding.

As a result, it is possible to prevent the thickness of the laminate sheet corresponding to the lower edges from being significantly thinned by a very simple method of adjusting the radius of curvature of the edge of the punching jig used for deep drawing forming, It is possible to prevent the loss of the electrolytic solution and the penetration of water and to secure the safety of the battery without the problem of the electrode assembly being pushed or deformed to the ruptured portion and the radius of curvature of the upper edges is not too large, There is an effect that it can be prevented.

Although the present invention has been described with reference to the drawings and experimental data, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

Claims (18)

1. A pouch-type battery cell case made of a laminate sheet,
And an accommodating portion for accommodating the electrode assembly and the electrolyte;
The housing portion includes a base portion on which the electrode assembly is mounted on an upper surface, side walls surrounding side surfaces of the electrode assembly, and lower edges connecting the base portion and the side walls and having curved surfaces;
Wherein a curvature radius (R) of at least one of the lower edges is 0.8 mm to 1.5 mm. The battery cell case according to claim 1, wherein a curvature radius of all of the lower edges is 0.8 mm to 1.5 mm. The battery cell case according to claim 2, wherein a curvature radius of all of the lower edges is 1 mm to 1.5 mm. The battery cell case according to claim 1, wherein the battery cell case further includes a sealing portion extending from an outer periphery of the accommodating portion, and upper edges connecting the sealing portion to the side walls of the accommodating portion and having a curved surface;
Wherein a curvature radius of at least one of the upper edges is 0.3 mm to 1.0 mm in a range smaller than a curvature radius of an adjacent lower edge. 5. The battery cell case according to claim 4, wherein the curvature radii of all of the upper edges are 0.3 mm to 1.0 mm in a range smaller than a curvature radius of the adjacent lower edge. 6. The battery cell case according to claim 5, wherein the curvature radii of all the upper edges are 0.5 mm to 0.8 mm in a range smaller than a curvature radius of the adjacent lower edge. 7. A laminated sheet according to any one of claims 1 to 6, wherein the thickness of the laminate sheet at the lower edges with a radius of curvature in the range of 0.8 mm to 1.5 mm is 70 to 100% of the thickness of the laminate sheet of the base, wherein the thickness of the laminate sheet at the upper edges that are within the range of about 1.0 mm to about 1.0 mm is 50 to 80% of the thickness of the laminate sheet of the base. The battery cell case according to claim 1, wherein the battery cell case includes a first case including the accommodating portion, and a second case connected to one end of the first case to seal the accommodating portion. The battery cell case according to claim 1, wherein the battery cell case includes a first case including the accommodating portion, and a second case that seals the accommodating portion as a member independent of the first case. The battery cell case according to claim 8 or 9, wherein the second case has a flat structure without a storage portion. An apparatus for producing a battery cell case according to claim 1 by deep drawing molding,
A die jig having a depressed portion of a shape corresponding to the accommodating portion formed on an upper surface thereof and having a laminate sheet mounted on an open upper portion of the depressed portion for forming a deep drawing; And
A punching jig inserted into the indented portion of the die jig to form a receiving portion by deformation of the laminate sheet;
And,
Wherein the curvature radius r of at least one corner among the corners corresponding to the portions where the laminate sheet is deformed into the lower edges of the accommodating portion in the punching jig is 0.8 mm to 1.5 mm. . 12. The pegging jig as set forth in claim 11, wherein, in the die jig, a radius of curvature of at least one corner among corners corresponding to a portion where the laminate sheet is deformed to the upper edges of the accommodating portion is smaller than a radius of curvature of a corresponding corner of the punching jig Wherein the thickness of the battery cell case is 0.3 mm to 1.0 mm. 12. The method according to claim 11, wherein the thickness (t) of the laminate sheet corresponding to the portion deformed by the lower edges after the deep drawing forming is 70 to 100% of the thickness t0 of the laminate sheet before the deep drawing molding Battery cell case manufacturing apparatus. 14. The method according to claim 13, wherein the thickness (t) of the laminate sheet corresponding to the portion deformed by the upper edges after the deep drawing molding is 50 to 80% of the thickness t0 of the laminate sheet before the deep drawing molding Battery cell case manufacturing apparatus. A battery cell case according to claim 1;
An electrode assembly including a cathode, a cathode, and a separator interposed between the anode and the cathode; And
Electrolyte;
The battery cell comprising: A battery module comprising the battery cell according to claim 15. A battery pack comprising the battery module according to claim 16. A device comprising a battery pack according to claim 17.

Images