KR20160035422A - Novel Device for Unwinding Electrode Sheet and Secondary Battery Manufactured Using the Same - Google Patents

Abstract

The present invention relates to a device for unwinding an electrode sheet in order to produce a plurality of unit electrodes from a continuous electrode sheet where an electrode active material is coated on one side or both sides. The device for unwinding an electrode sheet comprises: an electrode roll where the continuous electrode sheet is winded; and a touch roll which induces unwinding of the electrode sheet while coming into contact with an outer side of the electrode roll in order to prevent folding of the electrode sheet generated from a withdrawing process of the electrode sheet.

Description

[0001] The present invention relates to a novel electrode sheet winding apparatus and a secondary battery produced using the same,

The present invention relates to an apparatus for winding an electrode sheet to produce a plurality of unit electrodes from a continuous electrode sheet coated with an electrode active material on one surface or both surfaces thereof, the electrode roll having the continuous electrode sheet wound thereon; And a touch roll for guiding the winding of the electrode sheet in a state of being in contact with the outer surface of the electrode roll so as to prevent folding of the electrode sheet caused in the drawing process of the electrode sheet .

As technology development and demand for mobile devices are increasing, the demand for batteries as energy sources is rapidly increasing, and accordingly, a lot of researches on batteries capable of meeting various demands have been conducted.

In addition, in recent years, rechargeable secondary batteries have been extensively used as an energy source or auxiliary power device for wireless mobile devices. In addition, the secondary battery is an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (HEV), and the like, which are proposed as solutions for air pollution of existing gasoline vehicles and diesel vehicles using fossil fuels (Plug-In HEV) and the like.

Such a secondary battery is manufactured such that the electrode assembly is embedded in the battery case together with the electrolyte solution. The electrode assembly is classified into a stack type, a folding type, and a stack-folding type according to a manufacturing method. In the case of the stacked or stacked-folded electrode assembly, the unit assembly has a structure in which an anode and a cathode are sequentially stacked with a separator interposed therebetween. In order to make such an electrode assembly, it is necessary to first manufacture a unit electrode laminate of a bi-cell or pull-cell structure.

In order to manufacture such a unit electrode electrode body, a unit electrode laminate body is cut into unit electrode intervals from an electrode sheet laminate having two or more continuous electrode sheets coated with electrode active materials on one or both surfaces thereof In the cutting process, a method of cutting an electrode sheet laminate using a cutter is generally used, and a continuous feeding method is widely used.

In order to manufacture a continuous electrode sheet as a unit electrode, it is necessary to roll the electrode sheet in a rolled state and slit the electrode sheet in accordance with the standard. To this end, in the step of unwinding the wound electrode, a phenomenon occurs in which the electrode is continuously folded due to the gap between the roll and the roll and the unspecified length of the electrode.

Therefore, it is very necessary to develop an apparatus for winding an electrode sheet to solve the above problems.

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.

An object of the present invention is to provide an electrode roll in which a continuous electrode sheet is wound; And a touch roll for guiding the winding of the electrode sheet in contact with the outer surface of the electrode roll, thereby preventing the folding of the electrode sheet.

It is still another object of the present invention to provide a secondary battery manufactured using such an apparatus.

In order to accomplish the above object, the present invention provides an apparatus for winding an electrode sheet for producing a plurality of unit electrodes from a continuous electrode sheet coated with an electrode active material on one surface or both surfaces thereof, An electrode roll on which the continuous electrode sheet is wound; And a touch roll for guiding the electrode sheet in a state of being in contact with the outer surface of the electrode roll so as to prevent folding of the electrode sheet occurring in the process of pulling out the electrode sheet.

Conventionally, by using a touch roll spaced apart from an electrode roll, a phenomenon that the electrode is folded due to the interval therebetween has occurred. In order to solve this problem, in the present invention, by including the touch roll which brings the electrode sheet into contact with the outer surface of the electrode roll, the gap between the roll and the roll can be narrowed to prevent electrode folding.

The diameter of the electrode roll is reduced as the electrode is wound. Therefore, when the touch roll is fixed, the distance between the roll and the roll increases as the winding is performed, resulting in the same electrode folding phenomenon as in the conventional art. Therefore, it is preferable that the position of the touch roll varies with the change in diameter of the electrode roll. Specifically, the touch roll includes a case in which the electrode roll is in contact with the upper outer surface and has a displacement in the vertical direction.

In one preferred example, the touch roll is connected to a guide in the vertical direction and has a displacement in the vertical direction. The vertical guide allows the touch roll to have only vertical displacement according to the diameter change of the electrode roll.

In another preferred embodiment, the touch roll may exhibit vertical displacement according to the diameter change of the electrode roll with its own weight. That is, as the diameter of the electrode roll becomes smaller, the position of the touch roll should be changed to the vertical downward direction. In the state where the touch roll is in contact with the upper outer surface of the electrode roll, since the weight of the touch roll itself is vertically downward, the touch roll is downward corresponding to the reduced diameter as the diameter of the electrode roll decreases.

The width of the touch roll is preferably larger than the width of the electrode sheet. When the width of the touch roll is smaller than the width of the electrode sheet, the folding phenomenon may occur in the presence of the electrode sheet which does not contact the touch roll, which is not preferable. The larger the contact area of the rolled electrode with the roll is, the more the folding phenomenon can be prevented. However, when the touch roll is too large, the volume is increased and the driving energy consumption is also increased. Therefore, the width of the touch roll is preferably 1.1 to 2 times the width of the electrode sheet.

In one preferred embodiment of the present invention, the diameter of the touch roll is 0.5 to 3 times the initial diameter of the electrode roll. When the diameter of the touch roll is less than 0.5 times the initial diameter of the electrode roll, it is not preferable since the area of the electrode sheet in contact with the touch roll is small and the angle is small to cause defective electrode sheet. Conversely, The size of the touch roll is too large to increase the volume of the device and increase driving energy consumption. For the above reasons, it is more preferable that the diameter of the touch roll is 0.7 to 1.5 times the initial diameter of the electrode roll.

Since the touch roll continuously contacts the electrode sheet, abrasion tends to occur due to friction of the electrode surface. If such abrasion occurs, the surface of the worn touch roll may cause damage to the electrode, which is undesirable. In order to solve this problem, one preferable example is to provide a wear-resistant coating on the surface of the touch roll. For the above reasons, it is more preferable that the abrasion-proof coating is a titanium coating.

In one example of the present invention, the touch roll may generate a vertical displacement using a separate power source. In this case, it is necessary to set a gap between the outer surface of the touch roll and the outer surface of the electrode roll in order to achieve the object of the present invention.

The power source may be any one capable of generating displacement of the touch roll, but in one preferred example, the power source is an air cylinder.

The present invention also provides an electrode manufacturing method for manufacturing an electrode using the apparatus, and provides an electrode manufactured using the apparatus.

The electrode may be an anode and / or a cathode.

The present invention also provides a secondary battery comprising the electrode. The secondary battery may be a lithium secondary battery having a structure in which a nonaqueous electrolyte solution containing a lithium salt is impregnated into an electrode assembly having a separator interposed between an anode and a cathode.

The positive electrode may be prepared, for example, by applying a positive electrode mixture containing a positive electrode active material on a positive electrode collector and then drying the positive electrode mixture. Optionally, a binder, a conductive material, a filler, .

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 positive electrode current collector may have fine unevenness formed on the surface thereof to increase the adhesive force of the positive electrode active material as in the case of the negative electrode current collector. Alternatively, the positive electrode current collector may have various properties such as a film, sheet, foil, net, porous body, Form is possible.

The cathode active material is a material capable of causing an electrochemical reaction. Examples of the lithium transition metal oxide include lithium cobalt oxide (LiCoO ₂ ) containing two or more transition metals and substituted with one or more transition metals, lithium Layered compounds such as nickel oxide (LiNiO ₂ ); Lithium manganese oxide substituted with one or more transition metals; Formula _{LiNi 1-y M y O 2} ( where, M = Co, Mn, Al , Cu, Fe, Mg, B, Cr, Zn or Ga and Lim, 0.01≤y≤0.7 include one or more elements of the element) A lithium nickel-based oxide represented by the following formula: _{Li 1 + z Ni 1/3 Co 1/3} Mn 1/3 O 2, Li 1 + z Ni 0.4 Mn 0.4 Co 0.2 O 2 , such as _{Li 1 + z Ni b Mn c} Co 1- (b + c + d _{) M d O (2-e} ) A e ( where, -0.5≤z≤0.5, 0.1≤b≤0.8, 0.1≤c≤0.8, 0≤d≤0.2 , 0≤e≤0.2, b + c + d <1, M = Al, Mg, Cr, Ti, Si or Y, and A = F, P or Cl; lithium nickel cobalt manganese composite oxide; And the formula _{Li 1 + x M 1-y} M 'y PO 4-z X z ( wherein, M = a transition metal, preferably Fe, Mn, Co or Ni, M' = Al, Mg or Ti, X = F, S or N, and -0.5? X? +0.5, 0? Y? 0.5, and 0? Z? 0.1), but the present invention is not limited thereto.

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, and various copolymers.

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

The negative electrode is prepared, for example, by applying a negative electrode mixture containing a negative electrode active material on a negative electrode collector and then drying the same. The negative electrode mixture may contain a conductive material, a binder, a filler, May be included.

The negative electrode collector is generally made to have a thickness of 3 to 500 mu m. The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery. Examples of the negative electrode current collector include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, copper or stainless steel Surface-treated with carbon, nickel, titanium, silver or the like, 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 active material may include, 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 &lt; 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, Bi ₂ O ₅ and the like; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

The binder, the conductive material, and the components added as necessary are the same as those in the negative electrode.

In some cases, a filler may be optionally added as a component to suppress the expansion of the negative electrode. Such a filler is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery, and examples thereof include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

In addition, other components such as a viscosity adjusting agent, an adhesion promoter and the like may be further included as a selective or a combination of two or more.

The viscosity modifier may be added up to 30% by weight based on the total weight of the negative electrode mixture as a component for adjusting the viscosity of the electrode mixture so that the mixing process of the electrode mixture and the coating process on the current collector may be easy. Examples of such viscosity modifiers include carboxymethylcellulose, polyvinylidene fluoride and the like, but are not limited thereto. In some cases, the above-described solvent may play a role as a viscosity adjusting agent.

The adhesion promoter may be added in an amount of 10% by weight or less based on the binder, for example, oxalic acid, adipic acid, Formic acid, acrylic acid derivatives, itaconic acid derivatives, and the like.

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 separator is generally 0.01 to 10 mu m, and the thickness is generally 5 to 300 mu m. 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 lithium salt-containing nonaqueous electrolyte solution is composed of an electrolyte solution and a lithium salt. As the electrolyte solution, a nonaqueous organic solvent, an organic solid electrolyte, and an inorganic solid electrolyte may be used.

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.

For the purpose of improving the charge / discharge characteristics and the flame retardancy, the electrolytic solution is preferably mixed with an organic solvent such as pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, Benzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, . 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 a preferred _{embodiment, 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 adding it to a mixed solvent of linear carbonate to prepare a lithium salt-containing non-aqueous electrolyte.

The present invention also provides a battery module including the lithium secondary battery as a unit cell, and a battery pack including the battery module.

The battery pack can be used as a power source for a medium and large-sized device requiring high temperature stability, long cycle characteristics, and high rate characteristics.

Preferred examples of the above medium to large devices include a power tool that is powered by an electric motor and moves; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; And a power storage system, but the present invention is not limited thereto.

As described above, in the electrode sheet unwinding apparatus according to the present invention, since the electrode sheet can be wound in a state in which the electrode roll and the touch roll are in contact with each other, folding of the electrode sheet can be prevented, The efficiency can be improved.

1 is a schematic cross-sectional view of a conventional electrode sheet unwinding device;
2 is a cross-sectional schematic diagram of an electrode sheet unwinding apparatus according to one embodiment of the present invention.

Hereinafter, the contents of 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 schematically shows a cross-sectional view of a conventional electrode sheet unwinding apparatus.

Referring to FIG. 1, the electrode sheet 300 is drawn out via a roll 200 spaced apart from the electrode roll 100 on which the electrode sheet 300 is continuously wound. In this case, since there is a distance between the electrode roll 100 and the roll 200, a continuous electrode folding phenomenon occurs.

2 is a cross-sectional view schematically showing an electrode sheet unwinding apparatus according to an embodiment of the present invention.

2, the electrode sheet unwinding apparatus according to one embodiment of the present invention guides the winding of the electrode sheet 310 in a state in which the electrode sheet 310 is in contact with the upper outer surface of the electrode roll 110, And a touch roll 210 for holding the touch screen. The touch roll 210 may be connected to the vertical guide 220 to have a vertical displacement.

In one preferred example, the touch roll 210 may exhibit vertical displacement according to the diameter of the electrode roll 110 due to its own weight. In addition, the touch roll 210 may generate a vertical displacement by using a separate power source, for example, an air cylinder.

In another example, the touch roll 210 may have a width greater than the width of the electrode sheet 310 to prevent folding, and the diameter of the touch roll 210 may be 0.7 to 1.5 times the initial diameter of the electrode roll 110 .

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 (18)

An apparatus for winding up an electrode sheet for producing a plurality of unit electrodes from a continuous electrode sheet coated with an electrode active material on one surface or both surfaces,
An electrode roll on which the continuous electrode sheet is wound; And
A touch roll for guiding the electrode sheet in a state of being in contact with the outer surface of the electrode roll so as to prevent folding of the electrode sheet caused in the drawing process of the electrode sheet;
And an electrode sheet winding device for winding the electrode sheet. The electrode sheet unwinding device according to claim 1, wherein the touch roll is in contact with an upper outer surface of the electrode roll and has a vertical displacement. The apparatus of claim 2, wherein the touch roll is connected to a vertical guide to have a vertical displacement. The apparatus of claim 2, wherein the touch roll exhibits vertical displacement according to a change in diameter of the electrode roll due to its own weight. The apparatus of claim 1, wherein the width of the touch roll is greater than the width of the electrode sheet. The electrode sheet winding apparatus according to claim 1, wherein the diameter of the touch roll is 0.5 to 3 times the initial diameter of the electrode roll. The apparatus of claim 1, wherein the surface of the touch roll is coated with a wear-resistant coating. The apparatus of claim 7, wherein the wear-resistant coating is a titanium coating. The apparatus of claim 2, wherein the touch roll generates a vertical displacement using a separate power source. The electrode sheet unwinding device according to claim 9, wherein the power source is an air cylinder. A method for manufacturing an electrode, wherein an electrode is manufactured using the apparatus according to any one of claims 1 to 10. An electrode, characterized in that it is manufactured using an apparatus according to any one of claims 1 to 10. A secondary battery comprising the electrode according to claim 12. 14. The secondary battery according to claim 13, wherein the secondary battery is a lithium secondary battery. A battery module comprising a secondary battery according to claim 13 as a unit cell. A battery pack comprising the battery module according to claim 15. 17. The battery pack according to claim 16, wherein the battery pack is used as a power source for a middle- or large-sized device. 18. The battery pack according to claim 17, wherein the middle- or large-sized device is an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a power storage system.

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