KR20140141742A - A Secondary Battery having Two More anode Taps - Google Patents

Abstract

In the present invention, provided is a jelly-roll type electrode assembly in which an anode and a cathode include an active material coating part on at least one surface of an anode current collector or a cathode current collector and are wound to face each other by using a separation membrane, wherein the anode has at least two anode taps.

Description

[0001] The present invention relates to a secondary battery having two or more anode taps,

The present invention relates to a secondary battery including two or more negative electrode tabs, and more particularly, to a secondary battery having a structure in which a jelly-roll is embedded in a battery case with an electrolyte impregnated therein, Wherein at least one of the positive electrode and the negative electrode includes an active material coated portion on at least one side of the whole of the positive electrode and the negative electrode opposite to each other using a separation membrane and at least two negative electrode tabs are mounted on the negative electrode, Battery.

The secondary battery is classified into a cylindrical battery and a prismatic battery in which the electrode assembly is housed in a cylindrical or rectangular metal can according to the shape of the battery case, and a pouch-shaped battery in which the electrode assembly is housed in a pouch-shaped case of an aluminum laminate sheet . Among them, the cylindrical battery has a relatively large capacity and is structurally stable.

The electrode assembly is embedded in a battery case. The electrode assembly includes a positive electrode / separator / negative electrode laminate structure. The positive electrode / separator / negative electrode has a jelly-roll type structure in which a separator is interposed between a positive electrode and a negative electrode coated with an active material. A stacked type in which a plurality of positive and negative electrodes of a predetermined size are stacked in a state in which a separator is interposed, and a stacked / folded type which is a composite structure of a jelly-roll type and a stack type. Among them, the jelly-roll type electrode assembly has an advantage of being easy to manufacture and having a high energy density per weight.

In this regard, FIG. 1 is a plan view of a negative electrode in a prior art jelly-roll type electrode assembly, and FIG. 2 is a partial schematic view of the jelly-roll type electrode assembly of FIG.

Referring to these drawings, the jelly-roll type (wound type) electrode assembly 20 basically comprises a cathode 10 on which a cathode (not shown) and a cathode tab 11 equipped with a cathode tab 12 are mounted, And a structure in which a separator is interposed therebetween and then is wound in a round shape.

In this structure, the positive electrode tab 12 and the negative electrode tab 11 are co-located on the winding outer end of the electrode assembly 20, and the negative electrode tab 11 protrudes from the open top of the top cap (not shown) And is electrically connected to the lower end of a negative electrode terminal (not shown).

On the other hand, when the secondary battery is used as a power source for a mobile phone or a notebook computer, a secondary battery that stably supplies a constant output is required. On the other hand, when the secondary battery is used as a power source for a power tool such as an electric drill, A secondary battery which can be stable and stable. That is, the power tool requires an instantaneous high output, and the heat generation of the battery is largely increased by continuous operation for a long time.

However, when a conventional secondary battery is used as a power source for a power tool that provides a high output in a short time, a high current is generated according to an instantaneous high output, so that the contact resistance between the electrode assembly and the electrode terminal So that it is difficult to provide a uniform output.

Accordingly, there is a high need for a prismatic secondary cell suitable for use as a high power source for a power tool or the like, so that it can be stably provided even at a high current transmitted to an electrode terminal.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems of the prior art and the technical problems required from the past.

Specifically, it is an object of the present invention to improve the safety of a battery by effectively reducing the heat generated in the battery by using two or more negative electrode tabs on the negative electrode of the jelly-roll, and to improve the defect rate Roll electrode assembly and a secondary battery including the jelly-roll electrode assembly.

In order to achieve the above object, a secondary battery according to the present invention is a secondary battery comprising a positive electrode collector or a negative electrode collector wound on a positive electrode and a negative electrode collector, the positive electrode including an active material coating portion on at least one surface thereof facing the negative electrode using a separator, And negative electrode tabs.

Therefore, in order to satisfy the above-described requirements, the secondary battery according to the present invention includes a plurality of negative electrode tabs, thereby effectively reducing the heat generated in the battery even if a high current is delivered to the electrode terminal according to the capacity of the battery. It is possible to improve the safety and significantly reduce the defect rate generated in manufacturing the jelly-roll electrode assembly.

The negative electrode taps according to the present invention may preferably have a structure in which they are mutually fused to constitute one current loop. Therefore, the defect rate can be greatly reduced as compared with the case where the thickness and size of the negative electrode tab are separately adjusted.

In one preferred embodiment, the negative electrode tabs may be respectively installed at both ends of the outermost one of the uncoated portions of the negative electrode, but the positions and the number of the negative electrode tabs may vary depending on the capacity of the battery cells. Of course.

In a specific example, the negative electrode tabs may be formed in an upward direction or a downward direction at a position overlapping with a center portion of the electrode assembly, centering on a virtual line passing through the central axis of the electrode assembly.

The negative electrode tabs may be a conductive plate in the form of a strip. Preferably, the negative electrode tabs may be formed at a close position so as to facilitate fusion.

For reference, a typical lithium secondary battery is composed of a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte containing a lithium salt.

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

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

The conductive material is usually added in an amount of 1 to 30% by weight based on the total weight of the mixture including the cathode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

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

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

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

Examples of the negative electrode active material include carbon such as non-graphitized carbon and graphite carbon; _{Li x Fe 2 O 3 (0≤x≤1} ), Li x WO 2 (0≤x≤1), Sn x Me 1-x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me' : Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, Halogen, 0 < x &lt; Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, and Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

The separation membrane is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the membrane is generally 0.01 to 10 micrometers, and the thickness is generally 5 to 300 micrometers. Such separation membranes include, for example, olefinic polymers such as polypropylene, which are chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane.

The non-aqueous electrolyte solution containing a lithium salt is composed of a polar organic electrolyte and a lithium salt. As the electrolytic solution, a non-aqueous liquid electrolytic solution, an organic solid electrolyte, an inorganic solid electrolyte and the like are used.

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

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

The inorganic solid electrolyte is, 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 can be used.

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

For the purpose of improving the charge-discharge characteristics and the flame retardancy, the non-aqueous liquid electrolyte may contain, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride and the like are added It is possible. In some cases, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart nonflammability, or a carbon dioxide gas may be further added to improve high-temperature storage characteristics.

Meanwhile, the negative electrode tabs may have a structure in which a protective tape of insulating material is attached on the interface with the current collector.

In one preferred example, the negative electrode tab and the positive electrode tab mounted on the positive electrode may be formed at a position close to the positive electrode so as to minimize the magnetic field generated by the positive and negative electrode currents.

The present invention provides a prismatic secondary battery including the electrode assembly as described above. The secondary battery may be manufactured by attaching the electrode assembly to a rectangular metal case or a pouch battery case, and then injecting an electrolyte solution. . Such a lithium secondary battery is well known in the art, so a description thereof will be omitted herein.

The present invention also provides a battery pack including two or more of the secondary batteries as a unit battery, and a device using the battery pack as a power source.

A preferable example of the device in which the battery pack according to the present invention can be used is an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a power storage device having a limited mounting space and exposed to frequent vibration and strong shock , But is not limited thereto.

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

As described above, the secondary battery according to the present invention can improve the safety of the battery by effectively reducing the heat generated in the battery by using two or more negative electrode tabs on the negative electrode of the jelly-roll, It is possible to largely reduce the defective rate generated at the time.

1 is a plan view of a negative electrode in a jelly-roll type electrode assembly of the prior art;
Figure 2 is a partial schematic view of the jelly-roll type electrode assembly of Figure 1;
3 is a plan view of a cathode according to one embodiment of the present invention;
4 is a perspective view of an electrode assembly after winding the jelly-roll type electrode assembly of FIG. 3;
5 is a partial schematic view of a prismatic battery incorporating the jelly-roll type electrode assembly 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.

FIG. 3 is a plan view of a negative electrode according to one embodiment of the present invention, and FIG. 4 is a perspective view of an electrode assembly after the jelly-roll type electrode assembly of FIG. 3 is wound. In FIG. 3, the shape before rounding is shown for convenience of explanation.

Referring to these drawings, a negative electrode 200 for manufacturing a jelly-roll type electrode assembly has a structure in which an active material 220 is coated on both sides of a current collector (copper foil 210) and a pair of negative electrode tabs (101) is attached by spot welding (250) or the like. An insulating tape 230 is attached to the interface between the negative electrode tabs 101 and the current collector 210 so as to extend slightly from the upper end to the lower end of the current collector 210.

In this structure, after the cathode is wound, a sealing tape 103 is attached to the outermost electrode end portion and compressed so as to be inserted into a prismatic battery case (not shown).

FIG. 5 is a partial schematic view of a prismatic battery incorporating the jelly-roll type electrode assembly according to the present invention.

Referring to FIG. 5 together with FIGS. 3 and 4, the prismatic battery 200 includes a jelly-roll type electrode assembly 100 housed in a rectangular metal case 110, And an upper cap 120 on which the cap 122 is formed.

The cathode of the electrode assembly 100 is electrically connected to the lower end of the cathode terminal 122 on the upper cap 120 through a pair of cathode taps 101 welded together to form a current loop, The negative electrode terminal 122 is insulated from the upper cap 120 by an insulating member 121. On the other hand, another electrode (for example, an anode) of the electrode assembly 100 is electrically connected to the upper cap 120 whose anode tab 102 is made of a conductive material such as aluminum, stainless steel, And forms a bipolar terminal by itself.

The rectangular case 110 and the electrode assembly 100 may be separated from each other in order to ensure the electrical insulation between the electrode assembly 100 and the upper cap 120 except for the positive electrode tab 102 and the pair of negative electrode tabs 102. [ Type insulating member 130 is inserted between the top cap 120 and the case 110 and welded together by welding along the contact surfaces of the top cap 120 and the case 110. [ Then, an electrolyte is injected through the electrolyte injection opening 123, and then the battery is sealed by welding, and the welding part is coated with epoxy or the like to complete battery assembly.

Accordingly, as described above, a pair of anode taps formed at both ends of the cathode are fused to each other to form one current loop, thereby effectively reducing the heat generation of the battery cells due to high power consumption.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

Claims (12)

The positive electrode current collector or the negative electrode current collector is wound on the positive electrode current collector and the negative electrode current collector such that the positive electrode and the negative electrode including the active material coating portion are opposed to each other using a separator and two or more negative electrode tabs are mounted on the negative electrode. Assembly. The electrode assembly of claim 1, wherein the negative electrode taps are mutually fused to form a current loop. The electrode assembly according to claim 1, wherein the negative electrode taps are respectively mounted on both ends of an outermost one of the uncoated portions on which the active material of the negative electrode is not coated. The electrode assembly according to claim 1, wherein the negative electrode tabs are formed in an upward direction or a downward direction at a position overlapping with a center portion of the electrode assembly about an imaginary line passing through a central axis of the electrode assembly. . The electrode assembly of claim 1, wherein the negative electrode tabs are strip-shaped conductive plates. The electrode assembly according to claim 1, wherein the negative electrode tabs are provided with a protective tape of an electrically insulating material on the interface with the current collector. The electrode assembly according to claim 1, wherein the negative electrode tab and the positive electrode tab mounted on the positive electrode are formed at positions close to each other to minimize a magnetic field. A secondary battery comprising an electrode assembly according to any one of claims 1 to 7. The secondary battery according to claim 8, wherein the electrode assembly is mounted on a rectangular or pouch battery case, and then an electrolyte is injected. The battery pack according to claim 9, wherein the secondary battery comprises two or more unit cells. A device comprising a battery pack according to claim 10. 12. The device of claim 11, wherein the device is an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a power storage device.

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