KR102143366B1 - Secondary Battery Cell Case Having Round Edge and Apparatus for Manufacturing the Same - Google Patents

Abstract

The present invention is a pouch-shaped battery cell case made of a laminate sheet, comprising a storage unit for accommodating an electrode assembly and an electrolyte; The receiving portion includes a base portion on which the electrode assembly is mounted on an upper surface, sidewalls surrounding side surfaces of the electrode assembly, and lower edges connecting the base portion and the sidewalls and having a curved surface; It provides a battery cell case and a manufacturing apparatus thereof, characterized in that the radius of curvature (R) of at least one of the lower edges is 0.8 mm to 1.5 mm.

Description

{Secondary Battery Cell Case Having Round Edge and Apparatus for Manufacturing the Same}

The present invention relates to a battery cell case having a curved edge and a manufacturing apparatus thereof, wherein sidewalls are connected at the base of the receiving portion in the battery cell case and the radius of curvature of the lower edges having the curved surface is increased. About.

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

The lithium secondary battery mainly uses a lithium-based oxide as a positive electrode active material and a carbon material as a negative electrode active material. In addition, lithium secondary batteries are manufactured in various shapes, and representative shapes include a cylindrical shape, a square shape, and a pouch type.

Double pouch-type secondary batteries are widely used for reasons such as the possibility of transformation of secondary batteries and high energy density. Such a pouch-type secondary battery largely includes an electrode assembly and a pouch case that accommodates and seals the electrode assembly.

The electrode assembly includes a negative electrode to which a negative electrode active material is applied to a negative electrode current collector, a positive electrode to which a positive electrode active material is applied to the positive electrode current collector, and a separator interposed between the negative electrode and the positive electrode. In addition, the separator is a solid film made of a polymer, and in addition to the function of insulating the anode and the cathode, the separator enables the movement of lithium ions between the anode and the cathode.

The pouch case includes a lower case in which an accommodating space for the electrode assembly is formed, and an upper case having four ends coupled to the four ends of the lower case. Here, the lower case is usually molded into a shape having an accommodating portion of the electrode assembly therein by deep drawing molding, and the coupling between the four ends of the upper and lower cases is usually made in a thermal bonding method.

Figure 1 discloses a perspective view of the battery cell case, Figure 2 is a process diagram showing a manufacturing process of the first case including such a storage unit, Figure 3 is a process corresponding to the process (c) to (d) of Figure 2 A cross-sectional view of a conventional storage unit manufacturing process is shown as an example, and FIG. 4 schematically shows an enlarged view of a portion A including edges of the first case of FIG. 3.

First, referring to FIG. 1, a pouch-type battery cell 10 case made of a laminate sheet includes a first case 20 including a concave storage part 21 in which an electrode assembly is accommodated, and the first case 20. ) Is connected to one end of the second case 30 to seal the storage unit. 1 shows a configuration in which the second case 30 is connected to one side of the first case 20, but of course, the second case 30 may be separated from the first case 20 to be.

The receiving portion 21 of the first case 20 has a large rectangular parallelepiped shape, and includes a base portion 22 on which the electrode assembly is mounted and sidewalls 23 surrounding the sides of the electrode assembly, and the base portion 22 and It consists of a structure including lower edges 24 connecting the side walls 23.

Further, the first case 20 is composed of a structure including the sealing portions 25 extending from the receiving portion 21 and upper edges 26 connecting the receiving portion 21 and the sealing portion 25 have.

Referring to FIGS. 2 to 4, as mentioned above, the first case 20 forms a storage part 21 in which the electrode assembly is embedded inside by deep drawing molding.

In the deep drawing molding, a die jig 40 and a die in which an indentation portion 41 having a shape corresponding to the receiving portion is formed on the upper surface, and a laminate sheet is mounted on the open upper portion of the indentation portion 41 for deep drawing formation. It is made by a punching jig 50 that is inserted into the recess of the jig and deforms the laminate sheet to perform a deep drawing process.

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

At this time, referring to Figs. 3 and 4 together, in the conventional die jig 40, the edge 42 corresponding to the portion where the laminate sheet 20 ′ is to be deformed into the upper edges 26 of the receiving unit 21 And a radius of curvature (R1, R2) of the corner 51 corresponding to the portion where the laminate sheet 20 ′ is to be deformed into the lower edges 24 of the receiving part 21 in the punching jig 50 to approximately 0.75 mm. As a result, the lower edges 24 and the upper edges 26 of the receiving portion 21 of the first case 20 formed by deep drawing have a radius of curvature R1' and R2' of approximately 0.75 mm, At this time, the thickness t2 of the laminate sheet corresponding to the edges 24 and 26 is thinner than 70% of the thickness t1 of the laminate sheet corresponding to the base portion 22.

Therefore, the strength of the edges, in particular, the lower edges that are not bonded to the second case is relatively weak, and the possibility of deformation is high, so problems such as cracks and ruptures easily occur due to external impacts, and the electrolyte and moisture are introduced. Alternatively, there is a problem of deteriorating battery safety, such as failure to prevent leakage, and the electrode assembly being pushed out or deformed to the ruptured portion.

Therefore, it is necessary to develop a pouch case capable of solving the safety problem caused by the molding process in a simpler way.

An object of the present invention is to solve the problems of the prior art as described above and technical problems that have been requested from the past.

An object of the present invention is to solve the problem that the thickness of the laminate sheet corresponding thereto decreases by increasing the radius of curvature of the lower edges of the receiving unit during molding processing for manufacturing a pouch-shaped battery cell case made of a laminate sheet, It is to provide a secondary battery case that can secure battery safety in a simple way.

Therefore, the pouch-type battery cell case according to the present invention for achieving the above object,

As a pouch-type battery cell case made of a laminate sheet,

It includes an electrode assembly and a storage unit for storing an electrolyte;

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

At least one of the lower edges has a radius of curvature R of 0.8 mm to 1.5 mm.

In the case of manufacturing in the form of increasing the radius of curvature of the edges as in the present invention, the rate of decrease in the thickness of the laminate sheet due to deep drawing molding for manufacturing the housing part of the case decreases, and the thickness is thinner compared to other parts. It is possible to minimize the reduction in the thickness of the lower edges vulnerable to external impact, thereby securing battery safety.

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

For this reason, it is preferable that all of the lower edges have a radius of curvature of 0.8 mm to 1.5 mm, and specifically, may be 1 mm to 1.5 mm.

Outside the above range, when the radius of curvature is less than 0.8 mm, there is no significant difference from the conventional one, and the thickness of the laminate sheet corresponding to the lower edges becomes thinner to 70% or less than the thickness of the laminate sheet corresponding to the base part, so that the strength is increased. Since it is weak and has a high possibility of deformation, problems such as cracks and ruptures easily occur due to external shocks, so that the inflow or outflow of electrolyte and moisture cannot be prevented, and the electrode assembly is pushed out or deformed to the ruptured part, thereby reducing battery safety. If there is a problem that is too large, exceeding 1.5 mm, the dead space increases due to an increase in the radius of curvature, and accordingly, the capacity to volume may decrease, which is not preferable.

Meanwhile, the battery cell case according to the present invention further includes a sealing part extending from an outer circumference of the receiving part, and upper edges connecting the side walls of the receiving part and the sealing part and having a curved surface; The radius of curvature of at least one of the upper edges may be 0.3 mm to 1.0 mm in a range smaller than the radius of curvature R'of an adjacent lower edge.

As described above, when the radius of curvature is large, the thickness reduction rate due to the deep drawing molding decreases, but in general, the difference in shape from the rectangular electrode assembly increases, so that the dead space in the receiving portion increases and a predetermined sealing force is obtained. For this reason, there is a problem in that the capacity relative to the total volume decreases due to a relatively increase in the width of the sealing part. Therefore, the upper edges, which are areas where the second case is bonded to be bonded to the first case to seal the case, may have a predetermined strength by bonding with the second case, which may occur as the radius of curvature is increased. In order to minimize the increase in dead space and secure the maximum capacity, it is desirable to configure the radius of curvature to be smaller than the radius of curvature of adjacent lower edges.

For this reason, it is preferable that all of the upper edges have a radius of curvature of 0.3 mm to 1.0 mm in a range less than the radius of curvature of each adjacent lower edge, and in detail, from 0.5 mm to a range less than the radius of curvature of each adjacent lower edge. Can be 0.8 mm.

Outside the above range, 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 drawing molding, and there is a problem that it is too vulnerable to external impacts, etc., and if it is too large beyond 1.0 mm As described above, the dead space increases according to the increase in the radius of curvature, and accordingly, the capacity relative to the volume may decrease, which is not preferable.

As described above, the rate of change in thickness of the laminate sheet can be predicted with this radius of curvature. Specifically, in the case of performing the deep drawing molding for the receiving part to have the radius of curvature, if the receiving part is formed to the same depth, the degree of stretching of the laminate sheet decreases as the radius of curvature increases, and the degree of stretching of the laminate sheet increases as the radius of curvature decreases. The radius of curvature of the same influences the extent to which the laminate sheet is stretched. In addition, the thickness of the laminate sheet varies depending on the degree of stretching of the laminate sheet.

Therefore, taking these points together, the thickness of the laminate sheet varies according to the radius of curvature, and specifically, when the radius of curvature increases, the degree of elongation of the laminate sheet is small, so that the rate of change in thickness is small. As it increases, the rate of change in thickness increases and becomes thinner.

Specifically, the thickness of the laminate sheet at the lower edges having the 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 at the base, and the upper edges having the radius of curvature in the range of 0.3 mm to 1.0 mm In the thickness of the laminate sheet may be 50 to 80% compared to the thickness of the laminate sheet at the base.

The thickness of the laminate sheet corresponds to the radius of curvature, but is somewhat affected by the depth setting of the housing. When the radius of curvature satisfies the above range, the thickness of the laminate sheet corresponding thereto satisfies the above range. It is desirable to manufacture. Accordingly, the depth of the receiving portion may also be determined within a range satisfying the above condition.

Outside the above range, when the thickness of the laminate sheet at the lower edges is less than 70% of the thickness of the laminate sheet at the base, there is no significant difference from the prior art, and the strength of the laminate sheet corresponding to the lower edges is weak and the possibility of deformation is high. It is not preferable because problems such as cracks and ruptures easily occur due to external impact, etc., so that the inflow or outflow of electrolyte and moisture cannot be prevented, and battery safety is deteriorated, such as the electrode assembly being pushed out or deformed to the ruptured part. In addition, outside the above range, when the thickness of the laminate sheet at the upper edges is less than 50% of the thickness of the laminate sheet at the base, the upper edges are similar to that the thickness of the laminate sheet corresponding to the lower edges is less than 70%. There is a problem that can cause the above problem by acting as a weak part of the case.

On the other hand, when the thickness of the laminate sheet at the upper edges exceeds 80% of the thickness of the laminate sheet at the base, it means that the radius of curvature is increased, so it is not preferable to have a problem due to the increase of the radius of curvature.

In general, a small amount of moisture generated or introduced during the manufacturing process of the battery is contained inside the battery cell, and in the case of a case made of a laminate sheet, moisture may penetrate from the outside through a crack or a ruptured part. This moisture reacts with lithium salts or electrode active materials in the electrolyte in the battery to degrade battery performance, and in particular, generates HF, causing serious problems in high temperature safety.

For example, if the electrolyte contains LiPF ₆ lithium salt, LiPF ₆ must exist in the form of Li ⁺ and PF ₆ ^- ions, but contrary to the intention, side reactions occur and unstable PF ₅ is generated as a by-product. It reacts with H ₂ O present in a trace amount in the electrolyte to form HF. HF destroys the SEI layer and causes dissolution of the anode, and this phenomenon occurs more remarkably at high temperatures. Depending on the type of lithium salt used as an electrolyte, materials such as HF, HCl, HBr, HI, etc. are generated in addition to HF, and thus there is a problem that it can act like HF as an acid.

In addition, when the electrolyte is depleted for reasons such as side reactions of the electrolyte, there is a problem in that the movement of lithium is limited, and thus the lifespan characteristics of the secondary battery are significantly deteriorated.

Furthermore, when a part of the case is ruptured due to an external impact, the electrode assembly is deformed severely, and ignition is easily caused by the deformation of the electrode assembly, and thus safety is very seriously affected.

Accordingly, the inventors of the present application confirmed that it is very important to prevent the lower edges of the receiving portion from being weakened due to the deep drawing molding of the laminate sheet, and thus completed the present invention having the above structure.

In other words, 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 receiving portion accommodating the electrode assembly is not too thin even after the deep drawing of the laminate sheet is molded. It can be safe without being ruptured even by impact.By preventing the occurrence of cracks or ruptures due to external impacts, loss of electrolyte and penetration of moisture are prevented, and the electrode assembly is pushed out or deformed into the ruptured part. Safety can be secured by preventing possible ignition.

Meanwhile, the battery cell case may include a first case including the receiving unit, a second case connected to one end of the first case to seal the receiving unit, or as a member independent from the first case and sealing the receiving unit It may have a structure including a second case. That is, the second case is not limited to the shape if it is connected to the first case as shown in FIG. 1 or if the electrode assembly is embedded and sealed by the first case and the second case such as independent members. No.

In addition, since the receiving portion may be formed in a size corresponding to the electrode assembly on one side of the case or may be formed on both sides of the case, in one example, the second case may be formed in a flat structure without the receiving portion, In another example, the second case may be configured to include a storage unit in a shape similar to that of the first case, but in detail for convenience and efficiency of the manufacturing process, the second case may be formed in a flat structure without the storage unit.

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. I can.

Here, since the outer coating layer must have excellent resistance from the external environment, it is made of a weather-resistant polymer having a predetermined or more tensile strength and weather resistance, and the weather-resistant polymer may be polyethylene phthalate (PET), polyethylene naphthalate (PEN), or nylon. .

In one specific example, the barrier layer may be a metal layer in order to exhibit a function of improving the strength of the case in addition to the function of preventing the introduction or leakage of foreign substances such as gas and moisture, and the metal layer is, for example, Aluminum, iron, copper, tin, nickel, cobalt, silver, stainless steel, and may be one selected from the group consisting of titanium, or an alloy thereof, but is not limited thereto.

The inner sealant layer is made of a heat-sealable polymer that has heat-sealability (heat-adhesiveness), has low hygroscopicity to suppress the intrusion of the electrolyte, and does not expand or erosion by the electrolyte, and the heat-sealable polymer is It may be a polyolefin, more preferably non-stretched polypropylene (cPP).

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

A die jig having an indented portion having a shape corresponding to the receiving portion formed on the upper surface thereof, and having a laminate sheet mounted on the open upper portion of the indented portion to form 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;

Contains,

In the punching jig, from among the edges corresponding to the portions where the laminate sheet is to be deformed into the lower edges of the receiving portion, the curvature radius (r) of at least one edge is 0.8 mm to 1.5 mm. Provides.

As described above, the accommodating part of the pouch-type battery cell case is performed by deep drawing molding. In order to make at least one of the lower edges of the accommodating part a curvature radius R of 0.8 mm to 1.5 mm, deep drawing In a jig for performing molding, a radius of curvature r of a portion corresponding to a portion to be deformed to the lower edges of the receiving portion should have the radius of curvature.

Here, in the deep drawing process of the laminate sheet, it is the punching jig that directly contacts the portion of the laminate sheet to be deformed to the lower edges of the receiving unit to determine the shape of the lower edge, so that the laminate sheet in the punching jig is The radius of curvature of the corners corresponding to the portion to be deformed into the lower edges may be 0.8 mm to 1.5 mm, and in detail, it may be 1.0 mm to 1.5 mm. At this time, it is more preferable that all of the lower edges have the radius of curvature, and the radius of curvature of the four corners of the lower surface directly contacting the laminate sheet in the punching jig is all 0.8 mm to 1.5 mm, specifically 1.0 mm to It is preferably 1.5 mm.

Similarly, in order to have a radius of curvature R of at least one of the upper edges of the receiving unit from 0.3 mm to 1.0 mm, in a jig for performing deep drawing molding, the area to be deformed into the upper edges of the receiving unit The radius of curvature r'of the corresponding part must have the radius of curvature.

Here, in the deep drawing process of the laminate sheet, it is the die jig that directly contacts the portion of the laminate sheet to be deformed to the upper edges of the receiving unit to determine the shape of the upper edge, so that the laminate sheet is 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 in detail, it may be 0.5 mm to 0.8 mm. At this time, it is more preferable that all of the upper edges have the radius of curvature, and the radius of curvature of all four corners of the upper surface directly contacting the laminate sheet in the die jig is 0.3 mm to 1.0 mm, in detail, 0.5 mm to It is preferably 0.8 mm.

Although described above, the radius of curvature has a relationship with the rate of change in thickness of the laminate sheet due to deep drawing molding. Specifically, the thickness of the laminate sheet corresponding to the portion deformed into edges after deep drawing molding varies according to the radius of curvature of the jigs. Specifically, as the radius of curvature of the jigs increases, the difference in thickness before and after deep drawing molding of the laminate sheet decreases.

For this reason, as described above, the thickness t of the laminate sheet corresponding to the portion deformed into lower edges after the deep drawing molding may be 70 to 100% of the thickness t0 of the laminate sheet before deep drawing molding. In addition, the thickness t of the laminate sheet corresponding to the portion deformed into 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 includes the battery cell case; An electrode assembly including an anode, a cathode, and a separator interposed between the anode and the cathode; And an electrolyte, wherein the battery cell is not particularly limited, and in detail, it may be a so-called lithium secondary battery in which an electrolyte solution containing a lithium salt is impregnated in the electrode assembly.

The electrode assembly is composed of a positive electrode and a negative electrode to enable charging and discharging, and for example, a folding type (jelly-roll) method, a stack type method, or a stack/ It can be made in a folding type.

The positive electrode is prepared by applying a mixture of a positive electrode active material, a conductive material, and a binder on a positive electrode current collector, followed by drying and pressing, and if necessary, a filler may be further added to the mixture.

The positive electrode current collector is generally made to a thickness of 3 to 500 μm. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel. Surface treatment of carbon, nickel, titanium, silver, or the like may be used on the surface of. The current collector may increase the adhesion of the positive electrode active material by forming fine irregularities on its surface, and various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics are possible.

The positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ) or lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as the formula Li _1+x Mn _2-x O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ ; 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 ; Ni-site type lithium nickel oxide represented 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, Zn or Ta, and x = 0.01 to 0.1) or Li ₂ Mn ₃ MO ₈ (where M = Fe, Co, A lithium manganese composite oxide represented by 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 part of Li in the formula is substituted with alkaline earth metal ions; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ and the like, but are not limited to these.

The conductive material is typically added in an amount of 1 to 30% by weight based on the total weight of the mixture including the positive electrode active material. Such a conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and examples thereof include graphite such as natural graphite or artificial graphite; Carbon blacks such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; Conductive fibers such as carbon fibers and metal fibers; 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 may be used.

The binder is a component that aids in bonding of an active material and a conductive material and bonding to a current collector, and is typically added in an amount of 1 to 30% by weight based on the total weight of the mixture including the positive electrode active material. Examples of such a binder include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butyrene rubber, fluorine rubber, and various copolymers.

The filler is selectively used as a component that suppresses the expansion of the positive electrode, and is not particularly limited as long as it is a fibrous material without causing chemical changes to the battery, and examples thereof include olefin-based polymers such as polyethylene and polypropylene; Fibrous materials such as glass fiber and carbon fiber are used.

The negative electrode is manufactured by coating, drying, and pressing the negative active material on a negative electrode current collector, and a conductive material, a binder, a filler, and the like as described above may be optionally further included if necessary.

The negative electrode current collector is generally made to have a thickness of 3 to 500 μm. Such a negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical changes to the battery, for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel. For the surface treatment with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloys, etc. may be used. In addition, like the positive electrode current collector, it is possible to enhance the bonding strength of the negative electrode active material by forming fine irregularities on the surface thereof, and may be used in various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics.

The negative active material may include, for example, carbon such as non-graphitized carbon and graphite-based 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' : Al, B, P, Si, elements of groups 1, 2, and 3 of the periodic table, halogen, metal complex oxides such as 0<x≦1;1≦y≦3;1≦z≦8); Lithium metal; Lithium alloy; Silicon-based alloys; Tin-based alloys; 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 needed are the same as described in the positive electrode.

The separator is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 μm, and the thickness is generally 5 to 300 μm. Examples of such a separation membrane include olefin-based polymers such as polypropylene having chemical resistance and hydrophobicity; Sheets or non-woven fabrics made of glass fiber or polyethylene are used. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.

The electrolyte may be a lithium salt-containing non-aqueous electrolyte, and the lithium salt-containing non-aqueous electrolyte consists of a non-aqueous electrolyte and a lithium salt, and a non-aqueous organic solvent, an organic solid electrolyte, an inorganic solid electrolyte, etc. are used as the non-aqueous electrolyte. It is not limited to these only.

As the non-aqueous organic solvent, for example, N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma -Butyl lactone, 1,2-dimethoxy ethane, tetrahydroxy franc (franc), 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolone, formamide, dimethylformamide, dioxolone , Acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid tryster, trimethoxymethane, dioxolone derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbo Aprotic organic solvents such as nate derivatives, tetrahydrofuran derivatives, ethers, methyl pyropionate, and ethyl propionate may be used.

As the organic solid electrolyte, for example, a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, a poly agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, A polymerization agent or the like containing an ionic dissociating group may be used.

As the inorganic solid electrolyte, for example, 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 may be used.

The lithium salt is a material 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.

In addition, for the purpose of improving charge/discharge characteristics, flame retardancy, etc., the electrolyte solution includes, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexaphosphate triamide, and nitro. Benzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxy ethanol, aluminum trichloride, etc. may be added. . In some cases, in order to impart non-flammability, a halogen-containing solvent such as carbon tetrachloride and ethylene trifluoride may be further included, and carbon dioxide gas may be further included to improve high-temperature storage characteristics, and FEC (Fluoro-Ethylene Carbonate), PRS (Propene sultone), and the like may be further included.

In one specific example, lithium salts such as LiPF ₆ , LiClO ₄ , LiBF ₄ , and LiN(SO ₂ CF ₃ ) ₂ are formed of a cyclic carbonate of EC or PC as a highly dielectric solvent and DEC, DMC or EMC of a low viscosity solvent. A lithium salt-containing non-aqueous electrolyte may be prepared by adding it to a mixed solvent of linear carbonate.

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 include, but is not limited to, a mobile electronic device, a power tool that is moved by receiving power by an electric motor; Electric vehicles including electric vehicles (EV), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and the like; An electric two-wheeled vehicle including an electric bicycle (E-bike) and an electric scooter (E-scooter); Electric golf carts; Power storage systems, etc., but are not limited thereto.

Since the structure and manufacturing method of such a device are well known in the art, detailed descriptions thereof are omitted herein.

As described above, the battery cell case according to the present invention adjusts the radius of curvature of the corners of the jigs forming the lower edges of the receiving unit in which the electrode assembly is embedded when forming the deep drawing for forming the receiving unit. By increasing the radius of curvature of the edges compared to the existing one, the thickness of the laminate sheet corresponding to the edges is prevented from being significantly thinned in a very simple way, thereby preventing the loss of electrolyte and penetration of moisture due to cracks or rupture due to external impacts, etc. In addition, there is an effect of securing battery safety without problems such as the electrode assembly being pushed out or deformed to the ruptured part.

In addition, at the same time, the battery cell case according to the present invention can minimize the decrease in capacity by preventing an increase in dead space that may occur as the radius of curvature increases by maintaining the radius of curvature of the upper edges having relatively excellent strength. There is an effect.

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

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

As described with reference to FIG. 1, the pouch-type battery cell case made of a laminate sheet includes a first case including a concave-shaped storage part in which an electrode assembly is accommodated, and a second case connected to the first case to seal the storage part. The first case includes: a base portion on which the electrode assembly is mounted, sidewalls surrounding sidewalls of the electrode assembly, and a storage unit including lower edges having curved surfaces and connecting the base and sidewalls of the storage unit; Sealing portions extending from the receiving portion; It is composed of a structure including upper edges having curved surfaces and connecting the sidewalls of the receiving portion and the sealing portion.

In addition, as described in Fig. 2, in the manufacturing process of the receiving unit due to the deep drawing molding, a laminate sheet is mounted on a die jig in which the indentation is formed (processes (a) and (b)), and then the punching jig is It consists of a method of inserting the indentation to deform the laminate sheet to correspond to the shape of the indentation and removing the punching jig (processes (c) and (d)).

In the present invention, the structure of the case and the manufacturing process of the storage unit have been described in detail in FIGS. 1 and 2. Hereinafter, according to an embodiment of the present invention, which is different from the conventional battery cell case of FIGS. 3 and 4 The present invention will be described with reference to a process of manufacturing a first case including an accommodating portion having a structure in which the radius of curvature of the lower edges of the battery cell case is increased, and an enlarged schematic diagram of the lower edge portions of the first case formed therefrom.

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

Referring to FIGS. 5 and 6, the first case 120 according to the present invention forms an accommodating part 121 in which an electrode assembly is embedded inside by deep drawing molding.

In the deep drawing molding, a laminate sheet is mounted on the upper part of the die jig 140, and the punching jig 150 is inserted into the indentation part 141 of the die jig 140 and removed to form the laminate sheet in the shape of the indentation part 141. It is achieved by forming the receiving portion 121 in a way that is deformed to correspond.

At this time, the radius of curvature (r') of the corner 142 corresponding to the portion where the laminate sheet is to be deformed into the upper edges 126 of the receiving part 121 in the die jig 140 is in the range of 0.3 mm to 1.0 mm. In the punching jig 150, the radius of curvature r of the corner 151 corresponding to the portion where the laminate sheet is to be deformed to the lower edges 124 of the receiving part 121 is in the range of 0.8 mm to 1.5 mm. Therefore, after performing the deep drawing process, the radius of curvature R of the lower edges 124 and the upper edges 126 of the first case 120 also have the above ranges, respectively.

This may occur as the upper edges 126 are bonded to the first case and have a predetermined strength compared to the lower edges 124 as the second case is bonded to seal the case. In order to minimize the increase in dead space and increase the width of the sealing part and to secure the maximum capacity, the radius of curvature (r') is maintained similarly to the prior art, while the lower edges 124, which are substantially more vulnerable when external impacts, have a radius of curvature. It is to prevent cracking or rupture by increasing (r) to prevent the thickness from becoming very thin.

The radius of curvature (r, r') of these jigs (140, 150) affects the extent to which the laminate sheet is stretched, and specifically, as the radius of curvature (r, r') increases, the extent of stretching of the laminate sheet Decreases.

Therefore, according to the present invention, by increasing the radius of curvature r of the punching jig 150 to a value of 0.8 mm to 1.5 mm, the thickness t of the laminate sheet corresponding to the lower edges 124 is laminated before deep drawing molding. It can be adjusted to 70% to 100% of the thickness of the sheet (t0), it is possible to prevent the lower edges 124 from becoming too thin, and the radius of curvature (r') of the die jig 140 is 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 deep drawing molding by using a value of.

As a result, it is a very simple method of adjusting the radius of curvature of the corners of the punching jig used for deep drawing molding, and prevents the thickness of the laminate sheet corresponding to the lower edges from becoming significantly thinner, cracking or rupture due to external impact, etc. Loss of electrolyte and penetration of moisture due to the like are prevented, and battery safety is secured without problems such as the electrode assembly being pushed out or deformed to the ruptured part, while the curvature radius of the upper edges is not too large, reducing the capacity to volume. There is an effect that can prevent it.

It has been described above with reference to drawings and experimental data according to an embodiment of the present invention, but those of ordinary skill in the field to which the present invention pertains to perform various applications and modifications within the scope of the present invention based on the above contents. It will be possible.

Claims (18)

As a pouch-type battery cell case made of a laminate sheet,
It includes an electrode assembly and a storage unit for storing an electrolyte;
The receiving portion includes a base portion on which the electrode assembly is mounted on an upper surface, sidewalls surrounding side surfaces of the electrode assembly, and lower edges connecting the base portion and the sidewalls and having a curved surface;
In the battery cell case , characterized in that the radius of curvature (R) of at least one of the lower edges is 0.8 mm to 1.5 mm ,
The battery cell case further includes a sealing portion extending from an outer circumference of the receiving portion, and upper edges connecting the sidewalls of the receiving portion and the sealing portion and having a curved surface;
The radius of curvature of at least one of the upper edges is 0.3 mm to 1.0 mm in a range smaller than the radius of curvature of the adjacent lower edge,
The thickness of the laminate sheet at the lower edges within the range of the radius of curvature of 0.8 mm to 1.5 mm is 70 to 100% of the thickness of the laminate sheet at the base, and the thickness of the laminate sheet at the upper edges within the range of the radius of curvature is 0.3 mm to 1.0 mm. Battery cell case, characterized in that the thickness is 50 to 80% of the thickness of the laminate sheet at the base. The battery cell case of claim 1, wherein the radius of curvature of all of the lower edges is 0.8 mm to 1.5 mm. The battery cell case of claim 2, wherein the radius of curvature of all of the lower edges is 1 mm to 1.5 mm. delete The battery cell case according to claim 1 , wherein a radius of curvature of all of the upper edges is 0.3 mm to 1.0 mm in a range smaller than that of each adjacent lower edge. The battery cell case according to claim 5, wherein a radius of curvature of all of the upper edges is 0.5 mm to 0.8 mm in a range smaller than that of each adjacent lower edge. delete The battery cell case according to claim 1, wherein the battery cell case comprises a first case including the storage unit, and a second case connected to one end of the first case to seal the storage unit. The battery cell case according to claim 1, wherein the battery cell case comprises a first case including the storage unit, and a second case that seals the storage unit as an independent member from the first case. The battery cell case according to claim 8 or 9, wherein the second case has a flat structure without a receiving part. An apparatus for manufacturing the battery cell case according to claim 1 by deep drawing molding,
A die jig having an indented portion having a shape corresponding to the receiving portion formed on the upper surface thereof, and having a laminate sheet mounted on the open upper portion of the indented portion to form 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;
Contains,
In the punching jig, from among the edges corresponding to the portions where the laminate sheet is to be deformed into the lower edges of the receiving portion, the curvature radius (r) of at least one edge is 0.8 mm to 1.5 mm. . The method of claim 11, wherein in the die jig, a radius of curvature of at least one corner of the corners corresponding to a portion where the laminate sheet is to be deformed into upper edges of the receiving unit is smaller than a radius of curvature of a corresponding corner of the punching jig. In, the battery cell case manufacturing apparatus, characterized in that the 0.3 mm to 1.0 mm. The method of claim 11, wherein the thickness (t) of the laminate sheet corresponding to the portion deformed into lower edges after the deep drawing molding is 70 to 100% of the thickness (t0) of the laminate sheet before deep drawing molding. Battery cell case manufacturing device. The method of claim 13, wherein the thickness (t) of the laminate sheet corresponding to the portion deformed into upper edges after the deep drawing molding is 50 to 80% of the thickness (t0) of the laminate sheet before deep drawing molding. Battery cell case manufacturing device. The battery cell case according to claim 1;
An electrode assembly including an anode, a cathode, and a separator interposed between the anode and the cathode; And
Electrolytes;
A battery cell comprising a. 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 the battery pack according to claim 17.

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