KR20060092421A - Pouch-typed battery of improved stability - Google Patents

Abstract

The present invention provides a pouch-type battery having a lead-out portion for fixing the generator on the inner upper end of the accommodating part of the pouch-type battery case in which the power generator is seated, the battery is external force due to a drop or an external impact applied to the upper part of the battery Even if this is applied, the movement of the power generator is suppressed in the storage space and the internal safety of the battery can be improved by preventing the internal short circuit caused by the contact between the electrode terminal and the power generator.

Description

Pouch-typed Battery of Improved Stability

1 is an exploded perspective view of a pouch type battery including a general stacked power generator;

FIG. 2 is a top perspective view of the battery of FIG. 1 in an assembled state; FIG.

3 is a schematic diagram showing the configuration of electrode tabs and electrode leads in the spaced space between the inside of the battery case and the top surface of the power generator in the battery of FIG.

4 is an exploded perspective view of a pouch-type battery including a stack type power generator according to one embodiment of the present invention;

5 is a plan perspective view in a state in which the battery of FIG. 4 is assembled.

<Description of Major Symbols in Drawing>

100, 101: pouch type battery

200, 201: battery case

230, 231: storage

240, 241: protrusions

300: generator

400, 410: electrode lead

500: insulation film

The present invention relates to a pouch-type battery with improved safety, and more particularly, a protrusion for fixing the generator to the storage space is formed at an inner upper end of the accommodating portion of the pouch-type battery case, so that the battery is dropped or external to the battery. The impact is applied to move the generator to provide a battery that can prevent the internal short circuit caused by the contact of the electrode terminal and the generator.

As technology development and demand for mobile devices increase, the demand for batteries as energy sources is rapidly increasing, and accordingly, many studies on batteries that can meet various demands have been conducted.

Typically, there is a high demand for square and pouch type batteries that can be applied to products such as mobile phones with a thin thickness in terms of shape of the battery, and lithium ion batteries with high energy density, discharge voltage, and output stability in terms of materials, and lithium polymers. There is a high demand for secondary batteries such as batteries.

One of the major research challenges in these cells is to improve safety. For example, lithium secondary batteries may be subjected to high temperatures within the cell, which may be caused by abnormal operating conditions of the battery, such as internal short circuits, overcharge conditions exceeding the allowed currents and voltages, exposure to high temperatures, and impacts from drops. High pressure can cause the battery to explode. In one such case, there is a possibility that the secondary battery may generate an internal short circuit upon impact such as a drop or an action of an external force.

1 schematically illustrates a general structure of a pouch type secondary battery including a stack type power generator, and FIG. 2 illustrates a plan view of the battery in FIG.

First, referring to FIG. 1, the pouch type secondary battery 100 includes a positive electrode, a negative electrode, and a solid electrolyte coated separator disposed between the positive electrode and the positive electrode thereof in the pouch type battery case 200. And two electrode leads 400 and 410 electrically connected to the negative electrode tabs 302 and 304 are sealed to be exposed to the outside.

The battery case 200 is made of a soft packaging material such as an aluminum laminate sheet, and includes a case body 210 and a concave shape accommodating portion 230 on which the generator 300 can be seated. It consists of a lid 220 connected as one body. The accommodating part 230 of the battery case 200 may be formed by molding a plate-shaped laminate sheet, for example, in a mold in which a shape corresponding thereto is imprinted so that the power generator 300 may be seated.

The generator 300 used in the pouch type secondary battery 100 may have a jelly roll type structure in addition to the stack type structure shown in FIG. 1. In the stack type generator 300, a plurality of positive electrode tabs 310 and a plurality of negative electrode tabs 320 are fused to each other and coupled to the electrode leads 400 and 410, respectively, and the battery case is attached to the electrode leads 400 and 410. Insulating film 500 is attached to the upper and lower surfaces in order to ensure electrical insulation and sealing properties with the (200).

The major disadvantage of the pouch type secondary battery 100 is that the battery case 200 is a soft packaging material of low strength, and thus can be easily deformed by external impact, and the power generation mounted to the case 200. The fixedness of the device 300 is inferior. Thus, when the battery falls or is subjected to an external shock, the generator 300 is moved so that the electrode tabs 302, 304 or the electrode leads 400, 410 on the top of the battery are opposite to the generator 300. Contact with the electrodes may cause a short circuit.

In this regard, referring to FIG. 2, the inside of the case 200 has a space in which a plurality of positive electrode tabs 310 and a plurality of negative electrode tabs 320 are fused and coupled to the electrode leads 400 and 410, respectively. It is spaced apart from the generator 300 to provide a. Therefore, in the state in which the power generator 300 is seated on the accommodating part 230 of the battery case 200, the upper ends a and b of both sides of the power generator 230 are fixed from the inner top surface of the battery case 200. It is spaced apart by the distance w. For this reason, the generator 300 may move upward by the separation distance w by the drop or the external impact.

This phenomenon is described in detail with reference to FIG. 3 as follows.

FIG. 3 is a partially enlarged view of an upper portion of a case inner side in which a plurality of positive electrode tabs are fused in a compact form and connected to a positive electrode lead in a secondary battery including a stacked power generator.

Referring to FIG. 3, the plurality of positive electrode tabs 302 extending from the positive electrode current collector 310 of the power generator 300 may be integrated by, for example, ultrasonic welding, laser welding, spot welding, soldering, or the like. It is coupled to the anode lead 400 in the form of a fusion unit 322 coupled to. The positive lead 400 is sealed by the battery case 200 while the opposite end to which the positive electrode tab fusion unit 322 is coupled is exposed to the outside. Since the plurality of positive electrode tabs 302 are integrally coupled to form a fusion portion 322, the inner upper portion of the battery case 200 is spaced apart from the top surface of the power generator 300 by a predetermined distance, and the fusion portion ( The positive electrode tabs 302 of 322 are V-shaped.

Thus, when the battery falls on its upper end, ie, toward the positive lead 400, the generator 300 may move to the inner upper end of the case 200 to cause an internal short circuit. That is, the positive electrode tab 302 or the positive electrode lead 400 may contact the negative electrode current collector or the active material of the power generator 300. This phenomenon is the same when the case 200 is deformed due to the physical shock applied to the battery and the power generator 300 is moved.

In this regard, Korean Patent Application Laid-Open No. 2003-95519 discloses a method for treating electrode tabs of a crude cell for lithium secondary batteries, wherein the polysilicon having excellent heat resistance and chemical resistance is formed so as to surround the electrode tabs in the fusion region where the lead and the tab member are connected. A method for preventing a short circuit caused by attaching an insulating tape in the form of a mid or polypropylene using an acrylic or silicone adhesive by damaging the metal part of the exterior member is disclosed. However, this configuration has the disadvantage that the short circuit between the tab and the exterior member can be prevented because the position of the insulating tape is placed on the sealing portion of the exterior member, and the short circuit inside the battery cannot be prevented. Since the adhesive is used, the adhesive strength falls while the electrolyte is in contact.

Also in Korean Patent Application Publication No. 2003-66959, in a stacked polymer battery, as a means for preventing the electrode tab from short-circuiting with the electrode plate having a different polarity, it is composed of polypropylene, polyethylene or amorphous polyimide-based polymer resin. A method of adhering or dripping an insulating member in the form of a film or a liquid onto the electrode tab is disclosed. In this case, however, since the part to which the insulating member is applied is part of the tab protruding from the electrode plate, it is impossible to secure a perfect short circuit, and there is a limit in terms of securing the battery safety against external impact.

In addition, in Korean Patent Application Laid-Open No. 1999-78101, in the rectangular lithium ion battery of a jelly roll-type power generator, the surface of the metal surface and the tab attached to the metal surface of the portion where the electrode active material is not coated is formed of polyimide (kapton) and poly Overcoating with propylene polymer material prevents abnormal heat generation of metal foil from being transferred to the separator, and the membrane to which the electrode active material directly contacts causes a short circuit first to block the flow of ions to secure battery stability. It is. However, the above technique is configured to prevent the electrode tab of the jelly roll type power generator from contacting the separator in the rectangular battery, and cannot be applied to the pouch type battery, and also cannot solve the problem of the pouch type battery as described above.

In Korean Patent Application Publication No. 2004-26544, in a pouch type secondary battery, it is possible to maintain a good sealing state between the externally protruded electrode tabs and the exterior member, effectively prevent a short circuit between the electrode tab and the exterior member, and solve the problem that the adhesive tape melts at once. In order to solve the problem, a method of sealing the upper and lower portions of a pouch case using an adhesive tape for insulating members such as natural rubber and synthetic rubber is disclosed. However, such an adhesive tape has a disadvantage in that adhesive strength falls while the electrolyte is in contact, and a short circuit between the tab and the exterior member can be prevented, but a short circuit inside the battery cannot be prevented.

Therefore, in the pouch type battery, there is a high need for a technology capable of ensuring the safety of the battery in a more efficient manner.

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

The inventors, after extensive research and various experiments, form a protrusion on the inner top of an accommodating part in which a power generator is seated in a pouch-type battery, which causes the power generator to move due to the drop of the battery or the application of an external material shock. It has been found that the present invention can prevent the contact between the electrode tab or the electrode lead and the generator, that is, the internal short circuit due to the movement of the generator, thereby completing the present invention.

Therefore, the pouch-type battery according to the present invention is characterized in that the lead-out portion for fixing the generator in the upper end of the receiving portion of the pouch-type battery case in which the generator is seated.

In the pouch type secondary battery of the present invention, since the generator is stably fixed in the storage space by the protrusion of the upper end of the housing, it reduces the possibility of the generator moving by the dropping of the battery or the application of an external shock, and thus the electrode tab or the electrode. By preventing the leads (hereinafter sometimes abbreviated as electrode terminals) from contacting the generator, internal short circuits can be prevented.

The pouch-shaped battery case generally consists of a case body in which an accommodating portion is formed and a cover formed integrally with such a body. In some cases, an accommodating portion is formed in the main body and the lid, respectively, and the battery case may have a size corresponding to the thickness of the generator when the accommodating space created by the accommodating portions when the main body and the lid are combined. Thus, a pouch type battery case each having an accommodating portion in a main body and a lid is disclosed in PCT International Application No. PCT / KR2004 / 3312 of the applicant, which is incorporated herein by reference.

The position of the protruding portion formed in the receiving portion may be anywhere in the upper end of the receiving portion except for the portion where the electrode tab is coupled with the electrode lead, and the size and number of the protruding portion are not particularly limited as long as they are for fixing the generator to the receiving portion. Do not.

In general, in the battery, the separator is made larger than these electrodes in order to prevent a short circuit due to contact between the positive electrode and the negative electrode, and the positive electrode is made slightly smaller than the negative electrode in consideration of the lithium ion precipitation occurring intermittently in the negative electrode during charging and discharging. In the power plant, the size of the components is in the order of anode <cathode <separator. This difference in size is also consistent with the order of the components in which the electrode terminals come in contact with the top of the generator, due to the drop of the battery or the action of external forces. Thus, the electrode terminal is more likely to contact the top of the cathode first than the anode, regardless of whether it is a positive electrode tab or a negative electrode tab. In view of this, a short circuit does not occur when the electrode terminal is a cathode tab because it preferentially contacts the cathode of the generator, but a short circuit is likely due to preferential contact with the cathode when the electrode terminal is a cathode tab. Therefore, the protrusion of the inner upper end of the housing is preferably formed at least around the anode.

In one preferred embodiment, the protrusion is formed symmetrically on both sides of the upper end of the housing portion can perform a balanced fixing of the power generator.

The generator seated on the receiving portion may be a stacked structure or a jellyroll type structure. Among them, the stacked generator generates a plurality of electrode tabs by fusion and bonding them to the electrode leads, so that the electrode tabs in the upper portion of the housing are relatively in contact with the generator. Therefore, the structure according to the present invention is particularly preferable in a pouch type battery including a stack type generator. Such a stack-type power generator is an electrode assembly in which a plurality of anodes and cathodes are sequentially stacked with a separator therebetween, including the stacking / discovery disclosed in Korean Patent Application Publication No. 2001-82059 of the present applicant. Stacking & folding generators are also included.

The pouch type battery according to the present invention can be used for various kinds of batteries, and preferably for lithium secondary batteries.

The lithium secondary battery is composed of a positive electrode, a negative electrode, a separator, and a lithium salt-containing nonaqueous electrolyte.

The positive electrode is prepared by, for example, applying a mixture of a positive electrode active material, a conductive agent, and a binder onto a positive electrode current collector, followed by drying, and optionally, a filler may be further added to the mixture.

The positive electrode 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 , Cu ₂ V ₂ O ₇ and the like; Ni-site type lithium nickel oxide represented by the formula LiNi _1-x M _x O ₂ , wherein 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 (wherein M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li ₂ Mn ₃ MO ₈ (wherein M = Fe, Co, Lithium manganese composite oxide represented by Ni, Cu or Zn); LiMn ₂ O _{4 in} which a 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 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, the surface of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel Surface treated with carbon, nickel, titanium, silver or the like can be used. The current collector may form fine irregularities on its surface to increase the adhesion of the positive electrode active material, and may be in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

The conductive agent is typically added in an amount of 1 to 50 wt% based on the total weight of the mixture including the positive electrode active material. Such a conductive agent is not particularly limited as long as it has conductivity without causing chemical change in the battery. Examples of the conductive agent include graphite such as natural graphite and artificial graphite; Carbon blacks such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder and nickel powder; Conductive whiskeys 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 that assists in bonding the active material and the conductive agent to the current collector, and is generally added in an amount of 1 to 50 wt% based on the total weight of the mixture including the positive electrode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, 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 inhibiting the expansion of the positive electrode, and is not particularly limited as long as it is a fibrous material without causing chemical change in the battery, for example, olefinic polymers such as polyethylene, polypropylene; Fibrous materials, such as glass fiber and carbon fiber, are used.

The negative electrode is manufactured by applying and drying a negative electrode material on the negative electrode current collector, and if necessary, the components as described above may be further included.

The negative electrode current collector is generally made to a thickness of 3 to 500 ㎛. Such a negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery. For example, the surface of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel Surface-treated with carbon, nickel, titanium, silver, and the like, aluminum-cadmium alloy, and the like can be used. In addition, like the positive electrode current collector, fine concavities and convexities may be formed on the surface to enhance the bonding strength of the negative electrode active material, and may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

The negative electrode material may be, for example, carbon such as hardly 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 ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8); Lithium metal; Lithium alloys; 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 metal oxides such as Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

The separator is interposed between the cathode 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 from 0.01 to 10 ㎛ ㎛, thickness is generally 5 ~ 300 ㎛. As such a separator, for example, olefin polymers such as chemical resistance and hydrophobic polypropylene; Sheets or non-woven fabrics made of glass fibers 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 lithium salt-containing non-aqueous electrolyte consists of a nonaqueous electrolyte and lithium. As the nonaqueous electrolyte, a nonaqueous electrolyte, a solid electrolyte, an inorganic solid electrolyte, and the like are used.

As said non-aqueous electrolyte, N-methyl- 2-pyrrolidinone, a propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyl Low lactone, 1,2-dimethoxy ethane, tetrahydroxy franc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolon, formamide, dimethylformamide, dioxolon, aceto Nitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxy methane, dioxorone derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative Aprotic organic solvents such as tetrahydrofuran derivatives, ethers, methyl pyroionate and ethyl propionate can be used.

Examples of the organic solid electrolytes include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, poly edgementation lysine, polyester sulfides, polyvinyl alcohols, polyvinylidene fluorides, Polymers containing ionic dissociating groups and the like can be used.

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

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

In addition, for the purpose of improving charge / discharge characteristics, flame retardancy, etc., for example, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexaphosphate triamide, etc. Nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, 2-methoxy ethanol, aluminum trichloride, etc. It may be. In some cases, in order to impart nonflammability, halogen-containing solvents 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.

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.

4 is an exploded perspective view schematically showing a pouch-type battery according to an embodiment of the present invention.

Referring to FIG. 4, the pouch-type battery 101 includes a pouch-type case 201 and a power generator 300 having a cover 221 integrally formed on the main body 211. The accommodating part 231 to which the generator 300 is seated is formed in the case body 211, and a pair of protrusions 240 and 242 are formed at both inner upper sides of the accommodating part 231. The generator 300 is composed of a stacked electrode assembly of anode / membrane / cathode, and a plurality of electrode tabs 302 and 304 extending from the anode and the cathode are fused to each other and coupled to the electrode leads 400 and 410. It is. An insulating film 500 is attached to upper and lower portions of the electrode leads 400 and 410 to ensure electrical insulation and sealing property with the battery case 200 in an assembled state.

When the generator 300 is seated in the housing 231 of the case 201, both upper end portions (a, b) of the generator 300 is in close contact with the lower ends of the protrusions (240, 242).

FIG. 5 is a plan view illustrating the case in which the power generator 300 is fused to the main body 211 by covering the case cover 221 in a state in which the power generator 300 is seated on the housing 231 of the case 200.

4 and 5 together, the generator 300 is seated in the housing 231 of the case body 211, and the contact portion (hatched portion) with the case body 211 is covered by covering the case cover 221. ) By heating and pressing, and then folding both sides of the case of the fusion site to obtain the shape as shown in FIG.

Since both upper end portions a and b of the power generator 300 are pressed by the protrusions 240 and 242 of the housing 231, the power generator 300 is stably fixed to the storage 231. Therefore, even if the battery 101 is dropped or an external shock is applied to the battery 101, the power generator 300 hardly moves in the accommodating part 231, so that the power generator 300 is connected to the electrode tab 302. , 304, or the electrode leads 400, 410.

Although the pouch-type battery according to one embodiment of the present invention has been described above, those skilled in the art will be able to perform various applications and modifications within the scope of the present invention based on the above contents. .

As described above, according to the present invention, the pouch-type battery is prevented from moving by the power generator in the storage space and preventing the electrode terminals from contacting the power generator even when an external force is applied due to a drop or an external shock applied to the upper part of the battery. Can improve the safety.

Claims (8)

A pouch type battery having a lead-out portion for fixing a generator at an inner upper end of a pouch-type battery case in which a generator is mounted. The pouch-type battery according to claim 1, wherein the pouch-type battery case comprises a case body in which a housing portion is formed and a cover formed integrally with the body. According to claim 1, wherein the pouch-type battery case has a housing portion formed in the main body and the lid, respectively, when the main body and the lid combined the storage space made by the respective receiving portion having a size corresponding to the thickness of the power generator Pouch type battery, characterized in that. The pouch type battery of claim 1, wherein the protrusion is formed around a positive electrode of an inner upper end of the housing. The pouch type battery of claim 1, wherein the protrusions are symmetrically formed on both sides of an upper end of the inner side of the housing. The pouch type battery of claim 1, wherein the power generator is a stack type or jelly roll type power generator. The pouch type battery according to claim 6, wherein the battery is a stacked power generator. The pouch type battery of claim 1, wherein the battery is a lithium secondary battery.

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