KR20150122601A - A secondary battery with improving capacity - Google Patents

Abstract

The present invention relates to a battery comprising: an electrode assembly comprising a positive electrode plate, a negative electrode plate, and a separation membrane; and a battery case which accommodates the electrode assembly and a certain amount of electrolyte, is sealed to expose two electrode terminals, connected to relevant electrode tabs of two electrode plates of the electrode assembly, to the outside, and has both attachment units folded to close sides. An upper end portion attachment unit of the battery case is bent toward the direction of an upper end side of a long axis of the battery case with respect to the long axis (Y direction) and a short axis (X direction) of the battery case. Two electrode terminals, arranged to horizontally cross on the upper end portion attachment unit, is bent toward the direction of the long axis of the battery case along the upper end side.

Description

A secondary battery with improved capacity < RTI ID = 0.0 >

The present invention relates to a battery having an increased capacity.

The secondary battery may be used in a detachable structure that is free to be inserted or removed depending on the type of external equipment to which the secondary battery is to be used, or may be used as a built-in structure in which the secondary battery is embedded in an external device. For example, devices such as notebooks can insert and leave batteries according to the user's needs, while devices such as some phones, MPEG Audio Layer-3 (MP3), tablet PCs, smart pads, etc., The use of built-in battery packs is also a problem.

On the other hand, the lithium secondary battery, which has recently been rapidly used, contains various combustible materials and has a serious disadvantage in terms of safety due to the danger of overheating, explosion, etc. due to overcharging, overcurrent and other physical external impacts. Therefore, a lithium secondary battery has a positive temperature coefficient (PTC) element, a protection circuit module (PCM), a thermal cut-out (TCO), and the like as safety elements capable of effectively controlling an abnormal state such as overcharging and overcurrent (Battery Management Unit) that controls the operation of the battery pack.

Since such a secondary battery is preferably manufactured with a small size and weight, a prismatic battery or a pouch-type battery having a small weight to capacity ratio is mainly used as a battery cell of a secondary battery. Particularly, a pouch-shaped battery using an aluminum laminate sheet or the like as an exterior member has recently attracted a great deal of attention due to its advantages such as low weight and low manufacturing cost.

However, since the conventional battery having such a structure has a limited length in relation to the device and the upper joint portion extends in the longitudinal direction of the battery case, the built-in battery housed in the battery case, that is, There is a problem that the power storage capacity and output of the battery are relatively lowered. That is, due to the upper joint, the capacity of the battery is reduced compared to the same standard, and problems such as a drop in the battery pack or a large internal short circuit upon application of an external shock may be caused due to a structure-

Therefore, a battery having a specific structure capable of solving the above problems is very much needed.

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.

It is an object of the present invention to increase the length of an electrode assembly accommodated in a battery case and an accommodating portion of the battery case by a width that the upper joint portion of the battery case occupies in the longitudinal direction of the battery case, And to provide a battery having a package structure capable of increasing power storage capacity and output of the battery.

Yet another object of the present invention is to provide a protection circuit mounted on an upper junction of a battery case, in which a thermal cut-out (TCO) formed on the back surface is in direct contact with the upper surface of the battery cell, Which can be used as a battery.

According to an aspect of the present invention, there is provided an electrode assembly comprising a positive electrode plate, a negative electrode plate, And a battery case which houses the electrode assembly and a predetermined amount of electrolyte and is sealed so that two electrode terminals connected to corresponding electrode tabs of the two electrode plates of the electrode assembly are exposed to the outside and the both side joints are folded on adjacent sides, In this case,

The upper joint portion of the battery case is bent to the upper end surface of the long axis of the battery case with respect to the long axis (Y direction) and the short axis (X direction) of the battery case, And the two electrode terminals are bent along the upper surface in the longitudinal direction of the battery case.

Therefore, by increasing the length of the battery case accommodating portion and the electrode assembly accommodated in the accommodating portion by the width of the top joint portion of the battery case in the longitudinal direction of the battery case, the power storage capacity and output Can be increased.

In one preferred example, the electrode assembly is preferably applicable to, but not limited to, a stacked electrode assembly or a jellyroll-type electrode assembly.

Preferably, the upper end joint portion of the battery case and the common portion of the both end joint portions are cut to a predetermined size. The size of the shared portion to be cut is determined according to the size of a portion where the upper joining portion and the both joining portions are overlapped when the upper joining portion is in contact with the upper surface of the battery case and the both joining portions are folded in contact with both side surfaces of the battery case. Therefore, when the size of the joint is large, the size of the shared portion to be cut is also increased.

In addition, by rounding the cut ends of the upper joint portion and the both side joint portions, it is possible to prevent the handler from being injured during the assembly process of the battery.

In one preferred embodiment, the inner corner corresponding to the top joint is configured to have a large radius of curvature, in order to compensate for the width of the joint reduced in accordance with the severance of the share. The width of the portion where the upper joining portion and the both joining portions meet is smaller than that of the upper joining portion and the both joining portions due to cutting of the corresponding common portion.

When the protection circuit is disposed on the upper surface of the folded battery case, the back surface of the protection circuit may be disposed in contact with the upper surface of the folded battery case. In a specific example, a thermal cut-out (TCO) may be attached to the back surface of the protection circuit so as to be in direct contact with the upper surface of the battery case.

Generally, the TCO is a part in which the current is cut off when the temperature rises and reaches a predetermined value. Since the TCO is in direct contact with the upper surface of the electrode assembly built in the battery case, .

When the inner corner portion of the battery case is configured to have a large radius of curvature in the preferred embodiment as described above, the corresponding end of the electrode assembly may also be configured in a corresponding shape. With this configuration, the capacity of the battery can be further increased.

The secondary battery according to the present invention is not particularly limited as long as the electrode assembly is mounted on the battery case of the laminate sheet, but it may preferably be a lithium secondary battery.

Such a lithium secondary battery is composed of a positive electrode, a negative electrode, an electrolyte and the like as is well known in the art and will be described in detail below.

Generally, the positive electrode is prepared, for example, by coating a mixture of a positive electrode active material, a conductive agent and a binder on a positive electrode current collector, and then drying the resultant. Optionally, a filler may be further added to the mixture.

The cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _{2 -x} O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; A Ni-site type lithium nickel oxide expressed by the formula LiNi _1-x M _x O ₂ (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); Formula _{LiMn 2-x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like. However, the present invention is not limited to these.

The 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 change in the battery, and may be formed of a material such as stainless steel, aluminum, nickel, titanium, sintered carbon, or a surface of aluminum or stainless steel 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 conductive agent is usually added in an amount of 1 to 50% by weight based on the total weight of the mixture including the cathode active material. Such a conductive agent is not particularly limited as long as it has electrical conductivity without causing a chemical change in the battery, and examples thereof include graphite such as natural graphite and 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 that assists in bonding of the active material and the conductive agent to the binder and in binding to the current collector, and is usually added in an amount of 1 to 50% by weight based on the total weight of the mixture containing the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.

The filler is optionally used as a component for suppressing the expansion of the anode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

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

The negative electrode 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 conductivity without causing chemical change in the battery, and may be formed of a material such as copper, stainless steel, aluminum, nickel, titanium, fired carbon, 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 material may be, 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 non-aqueous electrolyte containing a lithium salt is composed of a solvent for a nonaqueous electrolyte and a lithium salt. Examples of the solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, But are not limited to, lactone, 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 derivatives, Tetrahydrofuran derivatives, ether, methyl pyrophosphate, ethyl propionate and the like can be used.

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

In some cases, organic solid electrolytes, inorganic solid electrolytes, etc. may be used.

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

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

For the purpose of improving charge / discharge characteristics, flame retardancy, etc., non-aqueous electrolytes may be used in the form of, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride and the like are added It is possible. 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), FPC (fluoro-propylene carbonate), and the like.

In one preferred embodiment, the battery case may have a structure in which a sealing tape is attached to the entire outer circumferential surface excluding the electrode terminal portion. In a specific example, the sealing tape may be an insulating adhesive, but is not limited thereto .

The present invention provides a device using the secondary battery as a power source, and preferable examples of the device include a mobile phone, a portable computer, a smart phone, a tablet PC, a smart pad, a netbook, a LEV (Light Electronic Vehicle) Automobiles, hybrid electric vehicles, plug-in hybrid electric vehicles, and electric power storage devices.

As described above, the battery package structure according to the present invention enlarges the length of the battery case accommodating portion accommodated in the battery case and the electrode assembly accommodated in the accommodating portion by the width of the upper joint portion of the battery case occupied in the longitudinal direction of the battery case, Thereby increasing the power storage capacity and output of the battery compared to the external standard. Further, the thermal cut-out (TCO) formed on the back surface of the protection circuit is configured to be in direct contact with the battery cell, so that the heat generation of the battery can be detected more quickly.

1 is a perspective view of a battery cell according to the present invention;
2 is a schematic view of a battery according to the present invention and a conventional battery;
3 is a schematic diagram of a manufacturing process of a battery according to one embodiment of the present invention;
4 is an enlarged view of the portion 'A' of FIG. 3;
5 is a schematic view of a battery according to the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

1 is a perspective view of a battery cell according to the present invention.

Referring to FIG. 1, a battery cell 100 is a plate-shaped battery cell 100 having electrode terminals (a positive electrode terminal 101 and a negative electrode terminal 102) formed at one end. Specifically, the plate-shaped battery cell 100 includes an electrode assembly (not shown) in a pouch-type case 110 of a laminate sheet including a metal layer (not shown) and a resin layer (not shown) And a sealing portion 116 is formed.

The battery cell 100 is formed in a plate-like plate structure so that the electrode terminals 101 and 102 are in surface contact with each other between terminal connection members (not shown).

In order to improve space efficiency, only the sealing portions 116 on both sides are bent so as to be closely contacted to the main body of the battery cell 100, and the upper sealing portion 120 is kept in the unfolded state, A PCM (not shown) is mounted.

FIG. 2 is a schematic view of a battery according to the present invention and a conventional battery.

Referring to FIG. 2 together with FIG. 1, a battery 100 according to the present invention includes an electrode assembly 150 composed of a positive electrode plate, a negative electrode plate, and a separator, And a battery case 110 configured to be sealed so as to expose the two electrode terminals 101 and 102 to the outside.

The battery 100 according to the present invention has a structure in which the TCO 300a and the PCB 200a are mounted long in the outward direction in a state where the upper sealing part 120a is not bent, The upper end sealing portion 120 and the both side sealing portion 116 of the battery case 110 are formed and the upper end sealing portion 120 of the battery case 110 increases the length of the electrode assembly 150, The two electrode terminals 101 and 102 disposed across the upper sealing portion 120 are folded toward the upper end face of the battery case 110 so as to increase the output of the battery case 110 in the longitudinal direction of the battery case 110 Is bent.

The TCO 300 connected to the PCB 200 directly contacts the upper surface of the electrode assembly 150 and contacts the inner surface of the upper sealing part 120 to raise the temperature of the battery 100, The current is quickly cut off.

FIG. 3 is a schematic view illustrating a manufacturing process of a battery according to an embodiment of the present invention. FIG. 4 is a schematic enlarged view of a portion 'A' of FIG. 3, Is shown in FIG.

Referring to these drawings with reference to FIG. 2, a manufacturing process of the battery 100 according to the present invention will be described below.

An upper end sealing portion 120 and a side sealing portion 116 are formed on an outer circumferential surface of the battery case 110. In a state where two electrode terminals 101 and 102 protrude from the upper end of the battery case 110, The shared portion 105 where the upper sealing portion 120 and the both side sealing portions 116 of the battery case 110 meet is cut so that the upper sealing portion 120 can be easily folded on the adjacent side surface of the battery case 300 have. Therefore, it is very easy to fold the upper sealing portion 120 and the both side sealing portions 116 to the adjacent side surfaces of the battery case 110.

Here, the shared portion 105 is rounded at each end, thereby preventing the operator from being injured in a battery assembling process or the like.

The sealing portion 105 of the upper sealing portion 120 and the opposite side sealing portion 116 is cut so that the sealing force of the cut portion is relatively lower than that of the upper sealing portion 120 and the both side sealing portions 116 do. Accordingly, the vacuum decompression of the electrode assembly 150 in a normal operating state can be concentrated in the cut-off region where the sealing force is relatively low. In order to solve such a problem, the inner upper corner portion 314 corresponding to the upper sealing portion 120 of the battery case 110 is formed with a large radius of curvature so as to secure a wide thickness of the joint portion. That is, the size of the joint portion reduced at the outer surface due to cutting of the sharing portion 105 can be supplemented at the inner surface to provide an excellent sealing force. In addition, the curvature radius of the inner upper corner portion 314 is set in an appropriate range, and when the internal pressure is higher than the threshold value, the pressurized gas can be discharged, thereby ensuring safety of the battery.

According to the present invention, since the TCO 300 electrically connected to the PCB 200 is attached to one surface of the upper sealing part 120, the upper sealing part 120 is bent, The TCO 300 directly contacts one surface of the electrode assembly 150 by being in close contact with the upper surface of the case 110. [ Also, as the upper sealing portion 120 is bent, the two electrode terminals 101 and 102 are also bent.

The insulating wire sealing tape 400 is attached along the outer circumferential surface of the battery case 110 excluding the two electrode terminals 101 and 102 in a state where the upper sealing part 120 and the both side sealing parts 116 are bent , The manufacturing process of the battery is completed.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (12)

An electrode assembly comprising a positive electrode plate, a negative electrode plate and a separator; And a battery case which houses the electrode assembly and a predetermined amount of electrolyte and is sealed so that two electrode terminals connected to corresponding electrode tabs of the two electrode plates of the electrode assembly are exposed to the outside and the both side joints are folded on adjacent sides, In this case,
The upper joint portion of the battery case is bent in the direction of the upper end surface of the battery case with respect to the long axis (Y direction) and the minor axis (X direction) of the battery case, Wherein the two electrode terminals are bent in the longitudinal direction of the battery case along the top surface. The battery according to claim 1, wherein the electrode assembly is a stacked electrode assembly or a jelly roll type electrode assembly. The battery according to claim 1, wherein a shared portion of the upper joint portion and both joint portions of the battery case are cut off.  4. The battery according to claim 3, wherein the cut ends of the cut ends and the ends of the both side joints are rounded. The battery according to claim 3 or 4, wherein the inner corner portion corresponding to the upper joint portion is formed to have a large radius of curvature in order to compensate for the width of the joint portion reduced due to the cutting of the common portion. The battery according to claim 1, wherein the protection circuit is disposed on the upper surface of the battery case in which the upper junction is folded, so that the back surface of the protection circuit is in contact with the upper surface. [7] The battery according to claim 6, wherein a TCO (Thermal Cut-out) is attached to the back surface of the protection circuit so as to directly contact the upper surface of the battery case. The battery according to claim 4, wherein an end portion of the electrode assembly is formed in a shape corresponding to a radius of curvature of the inner corner portion. The battery according to claim 1, wherein the battery is a lithium secondary battery. The battery according to claim 1, wherein an insulating line sealing tape is attached to the entire outer circumferential surface of the battery case excluding the electrode terminal portion. A device as claimed in any one of claims 1 to 10 as a power supply. 12. The device of claim 11, wherein the device is selected from a cell phone, a portable computer, a smart phone, a smart pad, a tablet PC, and a netbook.

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