KR101378453B1 - Manufacturing method for lithium secondary battery and lithium secondary battery manufactured by the same - Google Patents

Abstract

The present invention provides a method for manufacturing a lithium secondary battery with excellent high temperature stability by forming an electrode active material layer of a predetermined thickness on a ceramic coating layer which is formed on a separation membrane of the lithium secondary battery, and then contacting the separation membrane with an electrode which has the electrode active material layer, thereby having a structure in which the ceramic coating layer formed on the separation membrane and the electrode active material layer formed in the electrode are integrally combined. The manufacturing method according to the present invention comprises the following: a step of forming a ceramic coating layer by spreading a composition for ceramic coating to at least one side of the separation membrane and drying; a step of forming a first electrode active material layer by spreading slurry for forming the first electrode active material layer on the ceramic coating layer and drying; a step of forming a second electrode active material layer by spreading slurry for forming the second electrode active material layer on a current collector and drying; a step of combining the first electrode active material layer and the second electrode active material layer.

Description

Manufacturing Method of Lithium Secondary Battery and Lithium Secondary Battery Produced by It {MANUFACTURING METHOD FOR LITHIUM SECONDARY BATTERY AND LITHIUM SECONDARY BATTERY MANUFACTURED BY THE SAME}

The present invention relates to a method for manufacturing a lithium secondary battery and to a lithium secondary battery manufactured thereby, and more particularly, to form an electrode active material layer having a predetermined thickness on a ceramic coating layer formed after forming a ceramic coating layer on a separator of a lithium secondary battery. Then, by bonding to the electrode formed with the electrode active material layer, to have a structure in which the ceramic coating layer formed on the separator and the electrode active material layer formed on the electrode integrally bonded, a method for producing a lithium secondary battery excellent in high temperature stability in particular It is about.

Recently, lithium secondary batteries are not only power sources for portable electronic products including mobile phones, laptops, computers, etc., but also power tools, e-bikes, hybrid electric vehicle HEVs, and plug-in hybrid electric vehicles. The application is rapidly expanding to medium and large power sources such as automotive (plug-in HEV).

As the application field expands and the demand increases, the appearance and size of the battery are also changed in various ways, and life characteristics and safety are required to be superior to those required in conventional small batteries.

 Specifically, the explosion or fire caused by the lithium secondary battery during the use of the mobile phone is often occurring, and the demand for improving the thermal stability of the lithium secondary battery is increasing. In particular, in the case of a transportation device such as an electric vehicle, the safety of the battery is a transportation device. If the safety of the battery is not secured because it is a problem directly connected to the life of using, there is a limiting factor in the application of the lithium secondary battery to the transportation device.

Accordingly, studies are being actively conducted to increase the safety of the lithium secondary battery and to improve the high rate charging characteristics and the life characteristics.

On the other hand, in the case of a lithium secondary battery having a separator made of a polymer, when the alignment of the unit cell is misaligned due to vibration, dropping, winding during battery assembly, the separator does not perform the original function of separating the positive electrode and the negative electrode, There is a problem in that a short circuit between the positive electrode and the negative electrode occurs, and the battery cannot function as a battery.

In addition, the polymer separator itself, which is represented by a polyolefin, has a problem in that shrinkage occurs at a high temperature of 100 ° C. or higher, causing short circuits between electrodes, thereby deteriorating high temperature stability.

As a method for solving the problem of the separator, Patent Document 1 below forms a ceramic coating layer on at least one surface of the positive electrode or the negative electrode, thereby preventing a short circuit between the positive electrode and the negative electrode due to shrinkage and expansion of the separator, in a high temperature environment A technique for improving the heat resistance of the lithium secondary battery to improve the safety and life characteristics of the lithium secondary battery is disclosed.

However, in the technique disclosed in Patent Document 1 below, in order to form a ceramic coating layer, a low viscosity slurry containing ceramic powder, a dispersion medium, a binder, a surfactant, and the like having a fine particle size is used. Such a slurry is used as an electrode active material layer. When applied onto the ceramic powder, the ceramic powder, which is very small compared to the particle size of the active material constituting the electrode active material layer, penetrates into the gap between the particles of the electrode active material. Since a difference occurs in thickness, irregularities are formed in the ceramic coating layer, thereby making it difficult to form a ceramic coating layer having a uniform thickness. Accordingly, the ceramic coating layer may exhibit non-uniform insulation resistance, and as a result, may not meet the purpose of the ceramic coating to improve stability.

As an alternative to solve the problem of the ceramic coating layer formed on the electrode active material layer, a method of coating a ceramic material on a separator having no problem of non-uniform coating is considered, but the material constituting the separator (generally polyolefin-based synthetic resin) and ceramic Due to material differences between materials, a large difference occurs in the heat shrinkage rate, which leads to a deterioration in battery safety.

Republic of Korea Patent Publication No. 10-2008-0105853

The present invention has been researched and developed in order to solve the above problems of the prior art, the problem of the present invention can form a ceramic coating layer having a uniform electrical resistance to provide a method for producing a lithium secondary battery excellent in high temperature stability will be.

The present invention as a means for solving the above problems, (a) coating and drying the ceramic coating composition on at least one surface of the separator to form a ceramic coating layer; (b) applying and drying a slurry for forming a first electrode active material layer on the ceramic coating layer to form a first electrode active material layer; (c) applying and drying a slurry for forming a second electrode active material layer on the current collector to form a second electrode active material layer; And (d) bonding the first electrode active material layer and the second electrode active material layer to each other.

In the method of manufacturing a lithium secondary battery according to the present invention, the thickness of the first electrode active material layer formed on the separator may be 1/10 to 1/2 of the thickness of the second electrode active material layer.

In addition, in the method of manufacturing a lithium secondary battery according to the present invention, the first electrode active material layer and the second electrode active material layer may be formed of substantially the same material.

In addition, in the method of manufacturing a lithium secondary battery according to the present invention, the bonding between the first electrode active material layer and the second electrode active material layer is a material including a binder used in the first electrode active material layer or the second electrode active material layer. It can be done through.

In addition, in the method of manufacturing a lithium secondary battery according to the present invention, the porosity of the ceramic coating layer may be 45 to 75%.

In addition, in the method of manufacturing a lithium secondary battery according to the present invention, the ceramic coating layer may include a ceramic powder and a binder.

In addition, in the method of manufacturing a lithium secondary battery according to the present invention, the viscosity of the ceramic coating composition may be 50 ~ 200cPS.

In addition, in the method of manufacturing a lithium secondary battery according to the present invention, the ceramic powder may be alumina (Al ₂ O ₃ ), titania (TiO ₂ ), zirconia (ZrO ₂ ), silicon dioxide (Si0 ₂ ), tin oxide (Sn0). ₂ ), cerium oxide (Ce0 ₂ ), magnesium oxide (MgO), calcium oxide (CaO), yttria (Y ₂ O ₃ ) may be one or more selected from.

In addition, in the method of manufacturing a lithium secondary battery according to the present invention, the thickness of the ceramic coating layer may be 2 ~ 10㎛.

The present invention also provides a lithium secondary battery produced by the above-described method.

In the lithium secondary battery provided by the present invention, since the ceramic coating layer is formed on the separator, it is possible to eliminate the thickness nonuniformity and therefore the nonuniformity of resistance characteristics caused when the ceramic coating layer is formed on the electrode active material layer. Since the coating layer and the electrode active material layer are provided in an integrated form, the shape between the ceramic coating layer and the electrode active material layer is maintained even when the separator is deformed, thereby providing a highly stable lithium secondary battery.

1 is a view illustrating a process of laminating a separator and an electrode in manufacturing a lithium secondary battery according to the present invention.
2 is a view showing the configuration of a gravure roll for forming a ceramic coating layer in a separator for a lithium secondary battery according to the present invention.
3 is a micrograph showing a cross section of a lithium secondary battery manufactured according to an embodiment of the present invention.
Figure 4 shows the result of performing a high-temperature discharge test of 60 ℃ for the lithium secondary battery prepared according to the embodiment of the present invention and the lithium secondary battery prepared according to the comparative example.

The ceramic coating layer is coated on the electrode active material layer of the positive electrode or the negative electrode to prevent a short circuit between the positive electrode and the negative electrode, in case a problem occurs in a separator that prevents self discharge by ion exchange between the positive electrode and the negative electrode, thereby preventing a short circuit between the positive electrode and the negative electrode. The coating layer to increase the safety.

The coating composition for forming such a ceramic coating layer usually includes a ceramic powder having excellent electrical insulation, a binder which provides a bonding force between particles constituting the ceramic powder when applied, and a liquid dispersion medium for dispersing the ceramic powder. It is done by

As the ceramic powder, for example, alumina (Al ₂ O ₃ ), titania (TiO ₂ ), zirconia (ZrO ₂ ), silicon dioxide (Si0 ₂ ), tin oxide (Sn0 ₂ ), cerium oxide (Ce0 ₂ ), It may include one or more selected from magnesium oxide (MgO), calcium oxide (CaO), yttria (Y ₂ O ₃ ), etc., and in addition to these materials can prevent a short circuit between the positive electrode and the negative electrode constituting the lithium secondary battery As long as the material can realize electrical insulation, the material is not limited thereto.

The binder may be used without particular limitation as long as it is capable of imparting a predetermined bonding force between the bonding with the ceramic powder or the electrode active material layer formed on the ceramic coating layer when the ceramic coating layer is formed. For example, acrylic polymer materials such as butyl acrylate polymer, ethylhexyl acrylate polymer can be used. At this time, the binder is preferably included in the range of 0.01 to 10% based on the weight of the entire ceramic coating layer, if less than 0.01%, it is difficult to obtain a sufficient bonding force, if it exceeds 10% battery characteristics may be degraded to be.

As the dispersion medium, any material that can easily disperse and dissolve the ceramic powder and the binder and can be easily volatilized and removed after coating can be used without particular limitation. For example, NMP (n-methyl-2-pyrrolidinone) or Materials such as cyclohexanone can be used.

The ceramic coating composition may be prepared by injecting the ceramic powder, the binder, and the dispersion medium into a container and mixing the same. At this time, the viscosity of the prepared ceramic coating composition is preferably 50cPS ~ 200cPS, because if the viscosity is less than 50cPS coating composition is easy to flow during the application process, if the viscosity exceeds 200cPS it is difficult to form a uniform coating layer to be.

The separator used in the lithium secondary battery is a porous membrane having a thickness of 10 to 30 μm, which not only provides a passage through which lithium ions can actively move, but also prevents contact between the positive electrode and the negative electrode, and is a polyolefin-based porous thin film. This is used a lot.

The coating of the ceramic coating layer may be used without limitation as long as it can form a ceramic coating layer having a uniform thickness on the separator, such as gravure and tape casting. In general, a gravure coating method using a gravure roll is used to form a functional film capable of increasing safety in the separator, the positive electrode plate, and the negative electrode plate.

On the other hand, in the formation of the ceramic coating layer, the coating thickness of the ceramic coating composition is preferably 2 ~ 10㎛, the viscosity control of the ceramic coating composition for making the coating thickness less than 2㎛ is not easy, the coating thickness is 10 This is because if the thickness is larger than that, the separation of the ceramic coating layer is likely to occur during the application process.

In addition, since the electrolyte is injected into the ceramic coating layer, in order for the properties of the electrolyte to be smoothly expressed, the porosity of the formed ceramic coating layer is preferably 45 to 75%. If it exceeds 75%, the bonding strength of the ceramic coating layer is lowered and the ceramic coating layer is likely to fall off.

In addition, the applied ceramic coating composition is heated through a dryer to form a final ceramic coating layer through a drying process to remove the dispersion medium. At this time, when the drying temperature is less than 50 ℃, the drying rate is too slow, if it exceeds 100 ℃ may cause damage to the separator mainly made of polymer, it is preferable that the drying process is carried out in the range of 50 ~ 100 ℃.

First on the ceramic coating layer Electrode active material layer  Forming step

After the ceramic coating layer is formed on the separator as described above, a first electrode active material layer having a predetermined thickness is further formed on the ceramic coating layer.

In this case, the thickness of the first electrode active material layer is the thickness of the second electrode active material layer formed on the current collector and the first electrode active material layer formed on the separator in consideration of the target thickness of the electrode active material layer required for the lithium secondary battery. It is formed by adjusting the sum to be the target thickness.

The first electrode active material layer is formed through application and drying of a slurry including an electrode active material powder, a dispersion medium, a conductive material powder and a binder.

Of the electrode active materials, for example, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium copper oxide, lithium vanadium oxide, lithium nickel oxide, lithium manganese composite oxide, lithium iron phosphate, etc. may be used. It is not limited only to these. In addition, the negative electrode active materials include carbon and graphite materials such as natural graphite, artificial graphite, expanded graphite, carbon fiber, non-graphitizable carbon, carbon black, carbon nanotube, fullerene and activated carbon, and Al, Si, Sn alloys capable of alloying with lithium. Metals such as Ag, Bi, Mg, Zn, In, Ge, Pb, Pd, Pt, Ti, and compounds containing these elements, and metals and composites of the compounds with carbon and graphite materials, etc. may be used. It is not limited only to these.

The dispersion medium may be used as long as it can disperse the electrode active material and remove it after coating, and water is usually used.

The binder is a component that provides a bond between an electrode active material and a conductive material and a current collector, which is a component of an electrode, and is generally added in an amount of 1 to 50 wt% based on the total weight of the electrode mixture. Polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, poly Propylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, fluorine rubber, various copolymers thereof, and the like can be used.

The conductive material powder may be added in an amount of 1 to 20 wt% based on the total weight of the electrode mixture as a component for improving conductivity of the electrode 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 fibers and metal fibers may be used.

It is preferable that the viscosity of the slurry for forming the electrode active material layer is adjusted to 500 to 1500 cps. If the viscosity of the slurry for forming the electrode active material layer is less than 500 cps, it is difficult to form an electrode active material layer having a thickness of 5 to 15 μm, and the viscosity This is because when the content exceeds 1500 cps, the uniformity of the thickness cannot be secured with an excessively high viscosity.

In addition, the thickness of the first electrode active material layer preferably has 1/10 to 1/2 of the thickness of the second electrode active material layer formed on the current collector plate, when less than 1/10, it is difficult to form a uniform thickness, If more than 1/2 is the problem that the ceramic coating layer located below the crack or falling off occurs.

In addition, the coating of the electrode active material layer may be used without limitation as long as it is possible to form an electrode active material layer having a uniform thickness on the ceramic coating layer, such as gravure coating or tape casting, similarly to the formation of the ceramic coating layer. have.

House  On the second The electrode active material layer  Forming step

The current collector is a site where electrons move through an electrochemical reaction of the positive electrode or the negative electrode active material, and is not particularly limited as long as it is a conductive material without causing chemical changes in the battery. Preferably, copper, aluminum, Nickel, titanium, or alloys thereof, stainless steel, calcined carbon, and carbon, nickel, titanium, silver or the like coated on the surface of aluminum or stainless steel may be used.

In the same manner as forming the first electrode active material layer on the ceramic coating layer, a second electrode active material layer is formed on the current collector.

In this case, the first electrode active material layer and the second electrode active material layer are preferably made of substantially the same material.

1st Electrode active material layer  Second The electrode active material layer  Splicing step

In the bonding step of the first electrode active material layer and the second electrode active material layer, bonding the separator in which the ceramic coating layer and the first electrode active material layer are sequentially formed, and the current collector (ie, the electrode plate) on which the second electrode active material layer is formed. to be. That is, the side coated with the negative electrode active material on the separator is attached to the negative electrode plate coated with the negative electrode active material, and the side coated with the positive electrode active material is attached to the positive electrode plate coated with the positive electrode active material.

When the second electrode active material layer formed on the current collector and the first electrode active material layer formed on the ceramic coating layer are made of the same material, the second electrode active material layer may be simply bonded using an adhesive.

At this time, it is most preferable to include the dispersion medium and the binder used in the formation of the first and second electrode active material layers in the same ratio, but the adhesive is particularly limited as long as it can provide the adhesive force to the electrode active material powder without impairing the properties of the electrode active material. It doesn't work.

Attachment of the separator and the electrode may be performed through a conventional laminating process. For example, as illustrated in FIG. 1, the electrode plate 10 having the second electrode active material layer 11a formed thereon is disposed thereon. After applying an adhesive 20 (preferably a dispersion medium and a binder-containing material used to prepare a slurry for electrode active material coating) on the electrode plate 10, the ceramic coating layer 30 and the first electrode active material layer ( 11b) may be performed by arranging the first electrode active material layer 11b of the separator 40 sequentially formed to face downward, then pressing and attaching the same, followed by drying.

[Example]

Hereinafter, a preferred embodiment of the present invention will be described in detail.

An alumina (Al ₂ O ₃ ) powder having an average particle size of 0.9 μm, NMP as a solvent, and acrylonitrile as a binder were placed in a container and mixed with a stirrer to prepare alumina coating composition.

At this time, the mixing ratio of the alumina and the binder in the alumina coating composition was such that acrylonitrile was 4% by weight to 96% by weight of alumina. In addition, NMP was mixed in the solid content including alumina and acrylonitrile to be 40% by weight based on the total weight of the alumina coating composition.

Next, the alumina coating composition thus prepared was coated on the porous polyethylene separator.

Separation membrane was used having a thickness of 20㎛ in the case of the winding type, 12㎛ in the case of lamination type. And after the drying (inside) of the separator was subjected to ceramic paint coating to have a thickness of 2 ~ 5㎛.

Specifically, the alumina coating, as shown in Figure 2, the storage tank 110 for storing the composition for alumina coating, and the gravure rotatably disposed on the upper portion of the storage tank 110 in a clockwise or counterclockwise direction. It was performed through a micro gravure coating device 100 including a roll (Gravure roll) (120).

At this time, the separation membrane (S) is transferred from the supply roll (not shown) wound around the separation membrane (S) through the transfer rolls (130a, 130b) and the winding roll (not shown) while the alumina coating composition is attached to the gravure roll 120 The alumina coating composition is applied to the separator (S) to a thickness of about 2 ~ 5㎛ as being in contact with the).

The alumina coating composition applied as described above is heated by a dryer to remove NMP contained in the alumina coating composition by evaporation, thereby forming an alumina coating layer. In this example, the heating temperature of the dryer was set to 90 to 100 ° C.

The slurry for forming the first electrode active material layer is coated on the separator in which the alumina coating layer is formed. Specifically, the slurry for forming the first electrode active material layer includes artificial graphite as a negative electrode active material, styrene-butadiene rubber as a binder, carboxymethyl cellulose as a thickener, and acetylene black as a conductive material in a weight ratio of 96: 1.5: 1.5: 1. After mixing and dispersing in water, the viscosity was used to adjust the slurry to 500 ~ 1500cps.

The slurry was applied and dried on the alumina coating layer using the microgravure coating apparatus 100 described above, and then rolled to finally form a negative electrode active material layer having a thickness of about 10 μm.

In addition, after coating and drying the slurry for forming the first electrode active material layer on a copper foil having a thickness of 15 μm, which is a current collector, rolling was performed to form a negative electrode active material layer having a thickness of about 90 μm, and the negative electrode active material formed on the current collector. The thickness of the layer was adjusted to be about 5 to 10 μm thinner than the normal cathode.

Subsequently, the negative electrode plate and the separator are adhered using a press device, specifically, an adhesive (a low ratio aqueous binder solution, preferably a negative electrode active material slurry) is coated on the coated separator before passing through the press outlet nip of the press device. After the application of the solution), the negative electrode plate was placed on the separator, and then pressed. After pressing, the solvent was removed by drying under vacuum at a temperature of 80 to 110 ° C. to remove the solvent. .

Further, NMC / LMO (5: 5 weight ratio) powder as a positive electrode active material, polyvinylidene fluoride (PVdF) as a binder, and carbon powder as a conductive material were mixed in a weight ratio of 96: 2: 2, and then N-methyl Dispersion in -2-pyrrolidone to prepare a positive electrode slurry. The slurry was coated on an aluminum foil having a thickness of 20 μm, dried, and rolled to prepare a positive electrode plate.

A stacking electrode assembly was formed by using the anode prepared as described above, and a separator and a cathode bonded together, and EC / PC / EMC = 30: 5: 65 (volume ratio of 1.15 mol of lithium concentration (LiPF6)). The lithium secondary battery was prepared in the pouch together with the electrolyte solution.

3 is a micrograph showing a cross-sectional state of a cathode electrode prepared according to an embodiment of the present invention.

As shown in FIG. 3, a ceramic coating layer having a thickness of 2 to 5 μm is formed on the separator, and a negative electrode active material layer is formed to have a thickness of about 10 μm on the ceramic coating layer. It can be seen that it is bonded to the formed negative electrode active material layer.

[Comparative Example]

In addition, in order to compare and evaluate the characteristics of the lithium secondary battery manufactured according to the embodiment of the present invention, two kinds of lithium secondary batteries were manufactured by a conventional method.

Specifically, the positive electrode was prepared in the same manner as in the embodiment of the present invention, and the negative electrode was formed in a copper foil having a thickness of 15 μm, which is a current collector, with the same negative electrode active material layer as the embodiment of the present invention having a thickness of about 100 μm. One)

And using the alumina coating composition similar to the Example of this invention, the alumina coating layer of thickness about 2-5 micrometers was formed on the negative electrode active material layer. (Comparative Example 2)

The cathode prepared as described above and the anode coated with alumina were formed through a 20 μm thick polyethylene separator to form a stacking electrode assembly, and the lithium concentration (LiPF6) of 1.15 mol of EC / PC / EMC = 30: 5: A lithium secondary battery was prepared in an electrolyte solution and a pouch of 65 (volume ratio).

A lithium secondary battery manufactured according to an embodiment of the present invention and a lithium secondary battery prepared according to a comparative example were subjected to a high-temperature discharge test at 60 ° C. to evaluate and evaluate characteristics of a lithium secondary battery according to an embodiment of the present invention. 4 shows the results.

As confirmed in FIG. 4, the lithium secondary battery according to the embodiment of the present invention maintains good discharge capacity gradually down to 800 cycles, compared to the lithium secondary battery according to the comparative example, whereas the lithium secondary battery according to the comparative example is The discharge capacity drops sharply to 62.2% at about 530 cycles. That is, it can be seen that the high temperature stability of the lithium secondary battery according to the present invention is superior to the lithium secondary battery formed by the conventional method.

10: electrode 11a, b: electrode active material layer
12: current collector 20: adhesive
30: ceramic coating layer 40: separator
100: micro gravure coating device 110: storage tank
120: gravure roll 130a, b: feed roll
S: separator

Claims (8)

(a) coating and drying the ceramic coating composition on at least one surface of the separator to form a ceramic coating layer;
(b) applying and drying a slurry for forming a first electrode active material layer on the ceramic coating layer to form a first electrode active material layer;
(c) applying and drying a slurry for forming a second electrode active material layer on the current collector to form a second electrode active material layer; And
and (d) bonding the first electrode active material layer and the second electrode active material layer to each other. The method of claim 1,
The thickness of the first electrode active material layer is a manufacturing method of a lithium secondary battery, characterized in that 1/10 ~ 1/2 of the thickness of the second electrode active material layer. The method of claim 1,
The first electrode active material layer and the second electrode active material layer is a method of manufacturing a lithium secondary battery, characterized in that made of the same material. The method of claim 1,
Bonding of the first electrode active material layer and the second electrode active material layer is made of a material including a binder used in the first electrode active material layer or the second electrode active material layer. The method of claim 1,
The porosity of the ceramic coating layer is a manufacturing method of a lithium secondary battery, characterized in that 45 to 75%. The method of claim 1,
The viscosity of the ceramic coating composition is a method of manufacturing a lithium secondary battery, characterized in that 50 ~ 200cPS. The method of claim 1,
Ceramic powder constituting the ceramic coating layer is alumina (Al ₂ O ₃ ), titania (TiO ₂ ), zirconia (ZrO ₂ ), silicon dioxide (Si0 ₂ ), tin oxide (Sn0 ₂ ), cerium oxide (Ce0 ₂ ), A method for manufacturing a lithium secondary battery, characterized in that at least one selected from magnesium oxide (MgO), calcium oxide (CaO), yttria (Y ₂ O ₃ ). The lithium secondary battery manufactured by the method in any one of Claims 1-7.

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