KR101811838B1 - Insulating Composition for Electrode of Secondary Battery and Electrode Comprising Electrode Tab Coated by the Same - Google Patents

Abstract

The present invention relates to an insulating composition for a secondary battery electrode, which comprises a styrene butadiene rubber (SBR), a carboxymethyl cellulose (CMC), and a coloring agent, To the electrodes.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an insulating composition for a secondary battery electrode and an electrode coated with an insulating composition on the electrode tab.

The present invention relates to an insulating composition for a secondary battery electrode and an electrode coated with an insulating composition on the electrode tab.

2. Description of the Related Art As technology development and demand for mobile devices have increased, the demand for secondary batteries as energy sources has been rapidly increasing. Recently, the use of secondary batteries as power sources for electric vehicles (EV) and hybrid electric vehicles (HEV) .

Typically, in terms of the shape of a battery, there is a high demand for a prismatic secondary battery and a pouch-type secondary battery which can be applied to products such as mobile phones with a small thickness, and has advantages such as high energy density, discharge voltage, There is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries.

Also, the secondary battery is classified according to how the electrode assembly having the anode / separator / cathode structure is formed. Typically, the long battery-shaped anodes and cathodes are jelly- A stacked (stacked) electrode assembly in which a plurality of positive electrodes and negative electrodes cut in units of a predetermined size are sequentially stacked with a separator interposed therebetween, a stacked (stacked) electrode assembly in which a predetermined unit of positive and negative electrodes are stacked, A stack / folding type electrode assembly having a structure in which a bi-cell or full cell stacked in a single state is wound with a separating film or the like can be given.

Recently, a pouch-shaped battery having a structure in which a stacked or stacked / folded electrode assembly is embedded in a pouch-shaped battery case of an aluminum laminate sheet is attracting much attention due to low manufacturing cost, small weight, Its usage is also gradually increasing.

On the other hand, one of the main research tasks in such a secondary battery is to improve safety. The main cause of battery safety related accidents is due to abnormal temperature conditions due to a short circuit between the anode and the cathode. That is, in a normal situation, the separator is positioned between the anode and the cathode to maintain the electrical insulation, but the battery may cause overcharge or over discharge, dendritic growth of the electrode material or internal short-circuit by foreign matter, , A sharp object such as a screw penetrates the battery, or an unreasonable deformation is applied to the battery due to an external force.

Particularly, in the case of a stacked or stacked / folded type electrode assembly in which an anode and a cathode are cut to have a predetermined size and a plurality of stacked layers are stacked, the uncoated surface of the anode and the coated surface of the anode are short- A very large heat can be generated, which not only adversely affects the battery function but also causes a serious problem such as explosion.

Accordingly, there is a high need for a secondary battery technology which is excellent in terms of the processability and can effectively prevent the problem of battery heat generation due to the internal short circuit.

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.

The inventors of the present application have conducted intensive studies and various experiments and have found that by using an insulating composition comprising styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), and a coloring agent It has been confirmed that the possibility of an internal short circuit between the positive electrode and the negative electrode can be minimized in terms of processability when the insulating layer is formed on the electrode tab and the present invention has been accomplished.

Accordingly, the insulating composition for a secondary battery electrode according to the present invention is characterized by containing styrene butadiene rubber (SBR), carboxy methyl cellulose (CMC), and a coloring agent.

The inventors of the present application found that the SBR plays a role of securing the insulation of the composition and CMC improves the miscibility of the materials to prevent precipitation of the insulation composition thereafter, It was confirmed that the coating position, area, range, and thickness of the composition can be visually confirmed easily when the color is developed and then used to form an insulating layer on the electrode tab.

Therefore, all of the above materials must be included in the insulating composition, and even when any one of them is not contained, the desired effect of the present invention, that is, the insulating property and the easiness of the process can not be secured simultaneously .

Such an insulating composition may further comprise a solvent to easily mix and easily coat the materials on the electrode tab, wherein the solvent is selected such that the SBR and CMC are readily dispersed in emulsion form in water In consideration of the fact that it can be water-soluble, it can be water-based daily.

Specifically, the morphology formed by the SBR, the CMC, and the coloring agent contained in the insulating composition and the aqueous solvent is not limited. However, the materials may be dispersed in emulsion form or partially or completely dissolved form Lt; / RTI >

At this time, the total content of the SBR, CMC, and color developer may be 30 to 50 wt% based on the total weight of the insulating composition.

Exceeding the above range, when the weight of the solid content exceeds 50% by weight, the materials are not easily mixed in the solvent, and the viscosity is too high to lower the coating easiness of the composition, It is difficult to obtain a viscosity of not less than a predetermined value, so that it is difficult to maintain the coating form upon coating the composition and insufficient insulation can be secured as intended by the present invention.

In addition, the inventors of the present application have further investigated in order to optimally exhibit the effects of the present invention, and have found that the solid contents contained in the insulating composition are SBR 72 to 87 weight % Of CMC, 0.001 to 1 wt% of CMC, and 12 to 27 wt% of a coloring agent.

If the SBR exceeds 87 wt%, the viscosity of the composition becomes too high. If the SBR is less than 72 wt%, the insulation decreases. When the CMC exceeds 1 wt%, the SBR content The insulating property can not be sufficiently secured. If the content is less than 0.001% by weight, miscibility between the materials is lost and the precipitation phenomenon can not be prevented. When the coloring agent is contained in an amount of more than 27% by weight, the viscosity is increased. When the coloring agent is less than 12% by weight, a sufficient coloring effect can not be obtained. It is not easy to confirm, which is not preferable. Therefore, when satisfying the above-mentioned range, it is possible to effectively exhibit both effects of ensuring sufficient insulating property and ease of process.

The viscosity of the insulating composition according to the present invention including all of the above materials may be in the range of 1.0 cps to 3.0 cps to satisfy both coating easiness and shape retention.

As described above, when the viscosity of the composition is too high, the coating easiness of the composition is deteriorated. If the viscosity of the composition is too low, a predetermined viscosity can not be obtained even if the viscosity of the composition is too high. Because.

The coloring agent used in the insulating composition of the present invention is not limited as long as it is a material capable of exhibiting color in the composition, but a material which further increases the insulating property and does not adversely affect the battery is more preferable. Specifically, it may be a metal oxide , more specifically, the color expressible, aluminum oxide (Al ₂ O _3), ferrous oxide (FeO), ferric oxide (Fe ₂ O _3), the third iron oxide (Fe ₃ O ₄₎ , copper oxide (CuO), cobalt oxide (Co ₂ O _3), chromium oxide (Cr ₂ O _3), manganese oxide (MnO _2), nickel oxide (NiO), tin oxide (SnO _2), zinc oxide (ZnO) , Rutile (FeTiO ₂ ), and the like.

The present invention also provides an electrode in which an insulating layer is formed by coating the insulating composition on an electrode tab.

Specifically, the electrode according to the present invention includes an electrode current collector coated with an electrode active material on one or both surfaces thereof, and an electrode tab extending from an end of the electrode current collector and not coated with an electrode active material,

And an insulating layer coated on the electrode tab with an insulating composition including styrene butadiene rubber (SBR), carboxy methyl cellulose (CMC), and a coloring agent.

More specifically, the insulating layer may be formed to have a length of 1 mm to 3 mm in the extending direction of the electrode tab from the lower end of the electrode tab, On the other side, the insulating layer may be formed so as to cover 1% to 50% of the total length of the electrode tabs in the extending direction of the electrode tabs from the lower ends of the electrode tabs.

If the insulating layer is formed to be less than 1 mm in the extending direction of the electrode tab or is formed to be less than 1% of the total length of the electrode tabs, sufficient insulation can not be ensured and an internal short circuit may occur, If the thickness of the electrode tab is more than 3 mm in the extending direction of the electrode tab, or more than 50% of the total length of the electrode tab is used, an excessive amount of the insulating composition is used, It is difficult to secure a sufficient connection area with the electrode lead for electrical connection for the sake of original purpose.

Of course, the insulating layer may be formed to overlap with a portion to which the electrode active material is applied in a range of 0.5 mm or less.

The insulating layer may be formed to have a width equal to the width of the electrode tab perpendicular to the extending direction of the electrode tab of the electrode tab. However, the present invention is not limited thereto. It can be formed in a wider range.

Furthermore, the insulating layer may be formed to a thickness of 5 micrometers to 20 micrometers, and more specifically, may be formed to a thickness of 5 micrometers to 15 micrometers. In another aspect, May be formed to have a thickness of 30% to 100% of the coating thickness of the electrode active material on the electrode current collector.

Outside of the above range, if the forming thickness is less than 5 탆 or too thin to less than 30% of the electrode active material coating thickness, it is difficult to obtain the desired insulating property and there still exists a problem of internal short circuit. Conversely, If it is more than 100%, if it is too thick, the thickness of the electrode tab may be increased to increase the thickness of the electrode as a whole, which is not preferable.

On the other hand, the electrode may be a positive electrode or a negative electrode, but is not limited. Generally, the negative electrode is made larger than the positive electrode, so that there is a high possibility that the active material coated surface of the positive electrode contacts the active material coated surface of the negative electrode. Since the resistance of the uncoated surface of the positive electrode on which the active material is not coated is low and the heat generated on the positive electrode is large, it can be an anode in detail.

When the electrode is an anode, the electrode active material may be a cathode active material, and the electrode current collector may be a cathode current collector. The positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or the like. The positive electrode active material may further include a binder, a conductive material and a filler in addition to the positive electrode active material. Compounds substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _{2 -x} O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; A Ni-site type lithium nickel oxide expressed by the formula LiNi _1-x M _x O ₂ (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); Formula _{LiMn 2-x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); A lithium manganese composite oxide having a spinel structure represented by LiNi _x Mn _2-x O ₄ ; LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like. However, the present invention is not limited to these.

The cathode current collector generally has a thickness of 3 to 500 mu m. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon, aluminum or stainless steel A surface treated with carbon, nickel, titanium, silver or the like may be used. The current collector may have fine irregularities on the surface thereof to increase the adhesive force of the cathode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible.

The 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 electrode material mixture layer containing the electrode 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 conductive material is usually added in an amount of 1 to 50 wt% based on the total weight of the mixture including the anode 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 filler is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery, and is used selectively as a component for suppressing the expansion of the negative electrode. Examples of the filler include an oligomer based polymer such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

When the electrode is a cathode, the electrode active material may be a negative active material, and the electrode current collector may be a negative electrode collector. At this time, the negative electrode current collector may be coated with a binder, a conductive material, and a filler as needed in addition to the negative electrode active material as in the positive electrode.

The negative electrode active material may be 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 < 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, Bi ₂ O ₅ and the like; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials; Titanium oxide; Lithium titanium oxide and the like can be used.

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 present invention further provides an electrode assembly including the electrode, and a secondary battery including the electrode assembly.

Specifically, the electrode assembly includes a stacked (stacked) electrode assembly in which a plurality of positive electrodes and negative electrodes cut in a predetermined size unit are sequentially stacked with a separator interposed therebetween, A stack / folding type electrode assembly in which a bi-cell or a full cell stacked with a separator interposed therebetween is wrapped with a separation film or the like, or a stack / folding type electrode assembly in which a bi- Stacked < / RTI > electrode assembly.

Here, the separating film and the separating film are made of an insulating thin film having high ion permeability and mechanical strength. The pore diameter of the separation membrane and the separation film is generally 0.01 to 10 mu m, and the thickness is generally 5 to 300 mu m. Such separation membranes and separation films include, for example, olefin-based polymers such as polypropylene, which is chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like; Kraft paper and the like are used. Representative examples currently on the market include the Celgard ^R 2400, 2300 (from Hoechest Celanese Corp.), polypropylene separator (from Ube Industries Ltd. or Pall RAI), and polyethylene series (from Tonen or Entek).

In some cases, a gel polymer electrolyte may be coated on the separation membrane or the separation film to improve the stability of the cell. Representative examples of such a gel polymer include polyethylene oxide, polyvinylidene fluoride, and polyacrylonitrile.

On the other hand, when a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane.

The secondary battery has a structure in which a lithium salt-containing non-aqueous electrolyte is impregnated in the electrode assembly.

The lithium salt-containing non-aqueous electrolyte is composed of a non-aqueous electrolyte and a lithium salt. Non-aqueous organic solvents, organic solid electrolytes, and inorganic solid electrolytes are used as the non-aqueous electrolyte, but the present invention is not limited thereto.

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

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

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

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

The lithium salt-containing non-aqueous electrolyte may further contain, for the purpose of improving charge / discharge characteristics, flame retardancy, etc., for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salts, pyrrole, 2-methoxyethanol, trichloro-aluminum triflate, tetraethoxysilane, hexafluorophosphoric triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, Etc. may be added. In some cases, halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further added to impart nonflammability. In order to improve the high-temperature storage characteristics, carbon dioxide gas may be further added. FEC (Fluoro-Ethylene Carbonate, PRS (Propene sultone), and the like.

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

The lithium secondary battery according to the present invention can be used not only in a battery cell used as a power source of a small device but also as a unit cell in a middle- or large-sized battery module including a plurality of battery cells.

As described above, the insulating composition for a secondary battery electrode according to the present invention comprises styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), and a coloring agent, The application position and the application area of the insulating composition can be clearly confirmed and it is possible to prevent precipitation of the composition according to an appropriate content ratio of the materials contained in the insulating composition and to have the most suitable viscosity for easy application. It is possible to apply the insulating composition on the electrode tabs very well, thereby minimizing the possibility of internal short-circuiting between the positive electrode and the negative electrode, and securing the safety of the battery.

1 is a schematic view of an electrode in which an insulating layer is formed.

Hereinafter, the present invention will be described with reference to Examples. However, the following Examples are intended to illustrate the present invention, and the scope of the present invention is not limited thereto.

≪ Preparation Example 1 &

The insulating composition was prepared by adding 79.940% by weight of SBR, 0.008% by weight of CMC, 20.052% by weight of alumina (Al ₂ O ₃ ) as a coloring agent, and 40% by weight of solids content, based on the total weight of the solids.

≪ Preparation Example 2 &

The insulating composition was prepared by adding 73.94% by weight of SBR, 0.1% by weight of CMC, 25.96% by weight of copper oxide (CuO) as a coloring agent, and 50% by weight of solids content, based on the total weight of the solids.

≪ Example 1 >

An insulating layer was formed on the tabs of the positive electrode current collector by using the insulating composition prepared in Preparation Example 1, 1.7 mm in thickness and 10 micrometers in thickness in the extending direction of the electrode tabs from the lower end of the positive electrode tab as the end portion of the positive electrode active material Except that the electrodes were made by materials and methods known in the art.

≪ Example 2 >

An electrode was prepared in the same manner as in Example 1, except that an insulating layer was formed using the insulating composition prepared in Preparation Example 2.

≪ Example 3 >

Based on the solid content of the total weight of a SBR 68.94% by weight, CMC 1% by weight, and the coloring reagent was used to form the insulating composition prepared by the alumina (Al ₂ O ₃₎ a solids content of 30.06% by weight was added in an aqueous solution such that 40% by weight The electrode was prepared in the same manner as in Example 1.

<Example 4>

90.2% by weight of SBR and 0.08% by weight of CMC, and 9.92% by weight of alumina (Al ₂ O ₃ ) as a coloring agent, in an aqueous solution so as to have a solid content of 40% by weight The electrode was prepared in the same manner as in Example 1.

&Lt; Comparative Example 1 &

An electrode was prepared in the same manner as in Example 1, except that an insulating layer was not formed.

&Lt; Comparative Example 2 &

In the example, except on the basis of the solid content total weight as CMC 7.82% by weight, and the coloring reagent was used to form the insulating composition prepared by the alumina (Al ₂ O ₃₎ a solid content of 92.18 wt% was added in an aqueous solution such that 40% by weight 1 &lt; / RTI &gt;

&Lt; Comparative Example 3 &

Except for using an insulating composition prepared by adding 80.02% by weight of SBR based on the total weight of solid components, and 19.98% by weight of alumina (Al ₂ O ₃ ) as a coloring agent in an aqueous solution so as to have a solid content of 40% by weight 1 &lt; / RTI &gt;

<Experimental Example 1>

The insulation resistance of the insulating layers of Examples 1 to 4 and Comparative Examples 2 to 3 was measured and the change in electrolyte impregnation, high temperature storage, and physical impact was measured as compared with that at the time of coating, .

Example 1 Example 2 Example 3 Example 4 Comparative Example 2 Comparative Example 3 When coating > 300 MΩ > 300 MΩ > 300 MΩ > 300 MΩ <100 MΩ > 300 MΩ Impregnation with electrolyte (23 & 60 ℃, 30 days) No change No change No change No change No change No change High temperature storage (130 ~ 150 ℃, 12 hours) No change No change No change No change Insulating layer
crack Insulating layer
decrease Physical impact (bending up and down 500 times) No change No change No change No change No change Adherence to tab

Referring to Table 1, in Comparative Example 2, which does not include SBS, insufficient insulation resistance can not be secured. In Comparative Example 3, which does not include CMC, viscosity is increased, . Therefore, when the insulating layer is formed using a composition that is out of the range of the composition according to the present invention, it is not sufficient to secure the insulating property, and it may be difficult to maintain the insulating property according to the physical change.

<Experimental Example 2>

The surface and cross-section of the insulating layer and the occurrence of a short circuit at the time of physical impact were observed in the electrodes prepared in Examples 1 to 4 and Comparative Examples 1 to 3, respectively, and the results are shown in Table 2 below.

Surface and cross-section during coating Physical impact
(Bending up and down 500 times repeatedly) Example 1 Uniform distribution of coloring agent and SBR No change Example 2 Uniform distribution of coloring agent and SBR No change Example 3 Uniform distribution of coloring agent and SBR No change Example 4 Uniform distribution of coloring agent and SBR No change Comparative Example 1 - A tab short occurs Comparative Example 2 Mass distribution of coloring agents No change Comparative Example 3 Decrease in uniformity due to viscosity increase, increase in thickness (more than 700 mu m) A tab short occurs

Table 2 shows that, in the case of applying the insulating layer of the present invention, in any case, the insulating layer is maintained without inducing a physical short circuit, whereas in the comparative example, there is no insulating layer, It can not be maintained, and it can be understood that it is short-circuited.

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.

FIG. 1 is a schematic view for explaining the structure of an electrode provided with an insulating layer in more detail.

1, an electrode 100 according to the present invention includes an electrode current collector 110 having an electrode active material coated on one or both surfaces thereof, and an electrode assembly 110 extending from an end of the electrode current collector 110, And an electrode tab 120 that is not provided with an electrode tab 120. The electrode tab 120 includes an electrode tab 120 formed of an insulating material including styrene butadiene rubber (SBR), carboxy methyl cellulose (CMC) An insulating layer 130 coated with the composition is formed.

Specifically, the insulating layer 130 is formed on the entire length of the electrode tab 120, that is, 1% to 1% of the entire length L of the electrode tab 120 in the extending direction of the electrode tab 120 from the lower end of the electrode tab 120 And is formed to have a width w equal to the width w of the electrode tab 120 perpendicular to the extending direction of the electrode tab 120. [ This is because an insulating layer is formed only in an area where the facing portion of the facing electrode is in contact with the coated portion coated with the active material, thereby ensuring sufficient insulation for preventing internal short circuit, and at the same time enabling effective electrical connection between the tab and the lead.

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 (20)

Based on the total weight of the solid content, 72 to 87% by weight of styrene butadiene rubber (SBR), 0.001 to 1% by weight of carboxymethyl cellulose (CMC) and 12 to 27% by weight of a color developer,
Wherein the solvent further comprises an aqueous solvent. delete delete The insulating composition for a secondary battery electrode according to claim 1, wherein the total content of the SBR, CMC, and color developer ranges from 30 to 50% by weight based on the total weight of the insulating composition. delete The insulating composition for a secondary battery electrode according to claim 1, wherein the insulating composition has a viscosity of 1.0 cps to 3.0 cps. The insulating composition for a secondary battery electrode according to claim 1, wherein the coloring agent is a metal oxide. The method of claim 7, wherein the metal oxide is selected from the group consisting of aluminum oxide (Al ₂ O ₃ ), ferrous oxide (FeO), ferric oxide (Fe ₂ O ₃ ), ferric oxide (Fe ₃ O ₄ ) oxide (CuO), cobalt oxide (Co ₂ O _3), chromium oxide (Cr ₂ O _3), manganese oxide (MnO _2), nickel oxide (NiO), tin oxide (SnO _2), zinc oxide (ZnO), and Rutile (FeTiO ₂ ), and the like. And an electrode tab extending from an end of the electrode current collector and not coated with an electrode active material,
On the electrode tab, 72 to 87% by weight of styrene butadiene rubber (SBR), 0.001 to 1% by weight of carboxy methyl cellulose (CMC) and 12 to 27 And an insulating layer coated with an insulating composition further comprising an aqueous solvent. 10. The electrode of claim 9, wherein the insulating layer is formed to cover a portion of the electrode tab. The electrode according to claim 10, wherein the insulating layer is formed to have a length of 1 mm to 3 mm in the extending direction of the electrode tab from the lower end of the electrode tab. The electrode according to claim 10, wherein the insulating layer is formed so as to cover 1% to 50% of the total length of the electrode tabs in the extending direction of the electrode tabs from the lower ends of the electrode tabs. The electrode according to claim 9, wherein the insulating layer is formed to have the same width as the width of the electrode tab perpendicular to the extending direction of the electrode tab. The electrode according to claim 9, wherein the insulating layer is formed to a thickness of 5 micrometers to 20 micrometers. The electrode according to claim 9, wherein the insulating layer is formed to a thickness of 30% to 100% of a coating thickness of the electrode active material on the electrode current collector. The electrode according to claim 9, wherein the coloring agent is a metal oxide. 17. The method of claim 16 wherein the metal oxide is aluminum oxide (Al ₂ O _3), ferrous oxide (FeO), ferric oxide (Fe ₂ O _3), the third iron oxide (Fe ₃ O _4), copper oxide (CuO), cobalt oxide (Co ₂ O _3), chromium oxide (Cr ₂ O _3), manganese oxide (MnO _2), nickel oxide (NiO), tin oxide (SnO _2), zinc oxide (ZnO), and Rutile (FeTiO ₂ ). An electrode assembly comprising an electrode according to any one of claims 9 to 17. 19. The electrode assembly of claim 18, wherein the electrode assembly is a stacked electrode assembly, or a stacked / folded electrode assembly, or a stacked / laminated electrode assembly. A secondary battery comprising the electrode assembly according to claim 18.

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