KR20230067927A - Electrode drying device that can prevent thermal wrinkles in the non-coated portion - Google Patents

Abstract

The present invention relates to an electrode drying device capable of preventing thermal wrinkles on a non-coated area, and more particularly, to a coated portion (Sc) coated with an electrode active material on a metal foil and a non-coated area (Sc) not coated with the electrode active material ( An apparatus for drying an electrode sheet (S) containing Sn), comprising: a chamber in which the electrode sheet (S) is dried; a heating means provided in the upper part of the chamber to adjust the temperature in the chamber to a temperature for drying the electrode sheet; a guide roll for guiding movement of the electrode sheet in front and behind the chamber and maintaining tension of the electrode sheet; and a cooling means for cooling the uncoated portion of the electrode sheet.

Description

Electrode drying device that can prevent thermal wrinkles in the non-coated portion}

The present invention relates to an electrode drying device capable of preventing thermal wrinkles in the uncoated region, and more particularly, means for selectively cooling the uncoated region of an electrode to prevent thermal wrinkling occurring in the uncoated region during electrode drying. It relates to an electrode drying device capable of preventing thermal wrinkles in the uncoated portion provided therewith.

As technology development and demand for mobile devices such as smartphones, laptops, and digital cameras increase, technologies related to secondary batteries capable of charging and discharging are becoming more active. In addition, secondary batteries are an alternative energy source for fossil fuels that cause air pollutants, and are used in electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (P-HEVs) and energy storage devices (ESSs). etc. are applied.

Types of secondary batteries that are currently widely used include lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel hydride batteries, nickel zinc batteries, and the like.

Such a secondary battery is generally formed by accommodating an electrode assembly and an electrolyte solution in a battery case.

Here, the electrode assembly is a jelly-roll-type assembly consisting of a structure in which a separator is interposed between a long sheet-shaped positive electrode and a negative electrode and then wound, or a stacked assembly having a structure in which rectangular positive and negative electrodes are stacked with a separator interposed therebetween , It is common to consist of a stack-folding assembly in which unit cells are wound by a long separation film, or a lamination-stack assembly in which battery cells are stacked and attached to each other with a separator interposed therebetween.

In addition to the generally used liquid electrolyte, the electrolyte may be replaced with a solid electrolyte or a gel-type semi-solid electrolyte having an intermediate form between a liquid and a solid by adding an additive to the solid electrolyte.

The electrode assembly as described above is accommodated in a battery case, and depending on the type of battery case, a cylindrical battery and a prismatic battery in which the electrode assembly is embedded in a cylindrical or prismatic metal can, and an electrode assembly is embedded in a pouch-type case of aluminum laminate sheet It can be classified as a pouch type battery.

On the other hand, as a method of manufacturing an electrode of such a secondary battery, a slurry prepared by dispersing an active material, a conductive material, a binder, etc. in a solvent is applied on an electrode current collector and dried.

At this time, as a method of drying the electrode, there is a method of putting the sheet-type electrode into a drying device in a state of being wound on a roll and drying it. i have a problem

1 is a front view schematically showing the structure of a conventional electrode drying apparatus, and FIG. 2 is a non-coated state before (a) and after (b) inserting an electrode sheet into a chamber using the conventional electrode drying apparatus. it is a drawing

As shown in FIG. 1, the conventional electrode drying apparatus includes an empty chamber 11, a heating means 12, and a guide roll 13, and dries the electrode sheet 20 while passing through it.

According to such a device, there is an advantage in that the electrode sheet 20 can be dried evenly, but since the electrode sheet 20 is heated over the entire surface, as shown in FIG. Thermal wrinkles are generated in the exposed portion of the electrode current collector.

Looking specifically at the reason for the occurrence of such thermal wrinkles, when the electrode sheet enters a chamber having a higher temperature than the outside, the rigidity of an electrode current collector generally using a metal foil is lowered due to heat. .

On the other hand, since the guide rolls on both sides of the chamber continue to maintain a constant tension, more stretching occurs in the chamber at a higher temperature than room temperature.

3 is a graph measuring unit stress change of an electrode current collector before entering the chamber, inside the chamber, and after passing through the chamber.

Specifically, the process was carried out while the outside of the chamber was at room temperature and the temperature inside the chamber was maintained at 170° C., and this is the result of measuring unit stress for maintaining the elongation of the metal foil by 1 mm.

As shown in FIG. 3, despite the low unit stress required to maintain the elongation state in the high-temperature chamber, the conventional electrode drying apparatus maintains a constant tension regardless of this, so that the metal foil is more elongated. As a result, thermal wrinkles occur.

The reason why thermal wrinkles are not a problem in the coated area where the active material is relatively applied compared to the uncoated area is that the active material applied on the metal foil contributes to the mechanical properties and increases the tensile strength and partial rigidity, thereby reducing thermal wrinkles. This is because it does not occur or occurs at a level that is insignificant to the extent that it is not a problem.

On the other hand, as a method for suppressing the occurrence of such thermal wrinkles, in Patent Document 1, an air conditioner for cooling external air and a cool air discharge nozzle for discharging the cooled air to the uncoated area are provided near the outlet from which the electrode sheet of the chamber is discharged. An electrode drying apparatus is disclosed.

However, the device of Patent Document 1 supplies cold air to the uncoated area where thermal wrinkles have already occurred in a high-temperature chamber, and although it can be cooled more quickly than in the case of natural cooling outside the chamber, the occurrence of thermal wrinkles is fundamentally prevented. There are problems that cannot be suppressed.

Korean Registered Patent Publication No. 1810146

In order to solve the above problems, an object of the present invention is to provide an electrode drying device capable of preventing thermal wrinkles occurring in a non-coated area during electrode drying.

An electrode drying apparatus according to the present invention for achieving the above object is an apparatus for drying an electrode sheet including a coated portion coated with an electrode active material on a metal foil and a non-coated portion not coated with the electrode active material. A chamber that is a space in which the electrode sheet is dried, a heating means provided on the top of the chamber to adjust the temperature in the chamber to a temperature for drying the electrode sheet, guiding the movement of the electrode sheet in front and behind the chamber, and It is characterized in that it includes a guide roll for maintaining the tension of the sheet and a cooling means for cooling the uncoated portion of the electrode sheet.

In addition, the electrode drying apparatus according to the present invention is characterized in that the cooling means supplies cold air to the non-coating portion from the lower part of the electrode sheet.

In addition, the electrode drying apparatus according to the present invention is characterized in that the cooling unit maintains the temperature of the uncoated portion below a predetermined temperature by continuously supplying cold air to the uncoated portion from the start to the end of drying the electrode sheet.

In addition, the electrode drying apparatus according to the present invention is characterized in that the heating means is any one of an infrared lamp, a heat coil, or a hot air blower.

In addition, the electrode drying apparatus according to the present invention is characterized in that it further comprises a humidity controller for controlling the humidity in the chamber.

In addition, the electrode drying apparatus according to the present invention is characterized in that it further comprises a temperature sensor for measuring the temperature of the uncoated portion.

In addition, the electrode drying method according to the present invention is a method of drying an electrode sheet using the electrode drying apparatus according to the present invention, comprising the steps of a) putting the electrode sheet into a chamber to heat and dry it, and b) the above electrode sheet. It is characterized in that it comprises the step of cooling the uncoated part.

In addition, in the electrode drying method according to the present invention, the step b) continuously supplies cold air to the uncoated area from the lower part of the electrode sheet from the start to the end of drying the electrode sheet to maintain the temperature of the uncoated area below a certain temperature. It is characterized in that it is a step of doing.

In addition, in the electrode drying method according to the present invention, steps a) and steps b) are performed simultaneously.

In addition, the battery cell according to the present invention is characterized by including an electrode dried using the electrode drying method of the present invention.

In addition, the battery module according to the present invention is characterized in that it includes the battery cell according to the present invention.

According to the electrode drying device capable of preventing thermal wrinkles in the uncoated region of the present invention, a cooling means is provided under the uncoated region of the electrode to cool the uncoated region, thereby suppressing thermal wrinkles occurring in the uncoated region. there is

In addition, according to the electrode drying device capable of preventing thermal wrinkles in the uncoated region of the present invention, the high-temperature state of the metal foil can be alleviated, so that the binder distributed at the foil-electrode interface, which is directly involved in the adhesive force, moves to the electrode surface. It has the advantage of contributing to improving adhesion by suppressing binder migration.

1 is a front view schematically showing the structure of a conventional electrode drying apparatus.
2 is a view showing the uncoated state before (a) and after (b) putting an electrode sheet into a chamber using a conventional electrode drying apparatus.
3 is a graph measuring unit stress change of an electrode current collector before entering the chamber, inside the chamber, and after passing through the chamber.
4 is a perspective view schematically showing the structure of an electrode drying apparatus according to an embodiment of the present invention.
5 is a front view schematically showing the structure of an electrode drying apparatus according to an embodiment of the present invention.
6 is a cross-sectional view showing a section AA' of FIG. 4 .

In this application, terms such as "comprise", "have" or "have" are intended to indicate that there is a feature, number, step, component, part, or combination thereof described in the specification, but one or more other It should be understood that it does not preclude the possibility of addition or existence of features, numbers, steps, operations, components, parts, or combinations thereof.

In addition, the same reference numerals are used for parts having similar functions and actions throughout the drawings. Throughout the specification, when a part is said to be connected to another part, this includes not only the case where it is directly connected, but also the case where it is indirectly connected with another element interposed therebetween. In addition, including a certain component does not exclude other components unless otherwise stated, but means that other components may be further included.

Hereinafter, an electrode drying apparatus according to the present invention will be described with reference to the accompanying drawings.

Figure 4 is a perspective view schematically showing the structure of an electrode drying apparatus according to an embodiment of the present invention, Figure 5 is a front view schematically showing the structure of an electrode drying apparatus according to an embodiment of the present invention, and Figure 6 is a diagram It is a cross-sectional view showing the A-A' section of Fig. 4.

Looking at the electrode drying apparatus 1000 of the present invention with reference to FIGS. 4 to 6, the electrode drying apparatus 1000 is a device for continuously drying a long sheet-shaped electrode, that is, an electrode sheet S, (100), a heating means (200), a guide roll (300) and a cooling means (400).

First, the electrode sheet S to be dried is composed of a coated portion Sc coated with an electrode active material on a metal foil and a non-coated portion Sn not coated with the electrode active material.

The electrode active material can be divided into a positive electrode active material and a negative electrode active material, and a slurry is prepared by adding a conductive material and a binder to these active materials, and then applied on a metal foil.

The cathode active material may include layered compounds such as lithium cobalt oxide (LiCoO ₂ ) and lithium nickel oxide (LiNiO ₂ ), or 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 ; 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 ; Ni site type lithium nickel oxide represented 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, Zn or Ta and x = 0.01 to 0.1 or Li ₂ Mn ₃ MO ₈ where M = Fe, Co, Ni, Cu or Zn) lithium manganese composite oxide; LiMn ₂ O ₄ in which Li part of the formula is substituted with an alkaline earth metal ion; disulfide compounds; Fe ₂ (MoO ₄ ) ₃ etc. are mentioned, but it is not limited only to these.

The conductive material is typically added in an amount of 1 to 30% by weight based on the total weight of the mixture including the cathode active material.

The conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include 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; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

The binder is a component that assists in the binding of the active material and the conductive material and the binding to the current collector, and is typically added in an amount of 1 to 30% by weight based on the total weight of the mixture including the positive 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 butyrene rubber, fluororubber, various copolymers, and the like.

Examples of the negative electrode active material include carbon such as non-graphitizing carbon and graphite-based 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 composite oxides such as Al, B, P, Si, elements of groups 1, 2, and 3 of the periodic table, halogens, 0<x≤1;1≤y≤3;1≤z≤8); lithium metal; lithium alloy; silicon-based alloys; tin-based alloys; 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 , metal oxides such as Bi ₂ O ₅ ; conductive polymers such as polyacetylene; Li-Co-Ni based materials; Si, SiO, SiO ₂ Alone or a mixture thereof, such as Si-based, may be used, but is not limited to these.

In addition, the conductive material, the binder, and the like may be selectively further included in the anode active material.

The chamber 100 is for accommodating the electrode sheet S composed of the coated portion Sc coated with the electrode active material and the uncoated portion Sn not coated with the electrode active material and drying the coated portion Sc. .

Specifically, a part of the front and rear surfaces is open so that the supply and discharge of the electrode sheet S can be continuously performed while the inside is empty, and the remaining surfaces, that is, the lower surface, the upper surface, and a pair of side surfaces are sealed.

Therefore, it is possible to maintain the internal temperature within a predetermined range, and it is possible to prevent foreign matter or the like from the outside from entering.

The heating means 200 is a component for maintaining the temperature inside the aforementioned chamber 100 within a predetermined range. Specifically, the temperature inside the chamber 100 is maintained within a predetermined range so that the coated portion Sc of the electrode sheet S can be dried. , it is obvious that it can be additionally provided on the side.

The heating means 200 for performing the above function heats the inside of the chamber 100 or the electrode sheet S, such as heat, hot air, or a light source, and various known known A heat source may be used. For example, any one or a mixture of two or more of an infrared lamp, a heat coil, or a hot air balloon may be used.

Next, the guide roll 300 is located near the inlet and outlet of the chamber 100 to guide the movement of the electrode sheet S, and the electrode sheet S dried in the chamber 100 has a constant tension without sagging. to be able to maintain

As described above, the guide roll 300 supports the entire electrode sheet S to have a constant tension without distinguishing between the coated portion Sc and the uncoated portion Sn of the electrode sheet S. Accordingly, in the chamber 100 where the temperature is raised to a predetermined temperature, the non-coated portion Sn on which the active material of the electrode sheet S is not applied is relatively elongated, resulting in wrinkles.

However, the electrode drying apparatus 1000 of the present invention is equipped with a cooling means 400 capable of minimizing elongation by lowering the temperature of the uncoated region Sn, so that wrinkle formation can be suppressed.

Specifically, the cooling unit 400 is provided near the bottom of the electrode drying device 1000 so as to face the back side of the electrode sheet S on which the coated portion Sc is not formed, and cool air is directed toward the uncoated portion Sn. supply

The cooling unit 400 may employ various well-known cooling units, and may be manufactured in a desired shape using a device for cooling air, a nozzle for injecting cooled air to a desired location, and the like.

In addition, the cooling means 400 is discharged from the vicinity of the internal entrance of the chamber 100 to the vicinity of the exit of the chamber 100, that is, from the time the electrode sheet S enters the chamber 100 to the outside of the chamber 100. It may be provided so that it can be cooled by continuously supplying cold air to the uncoated part until the point of time.

In addition, when the cooling unit 400 is a nozzle that sprays cold air, a height adjusting unit capable of adjusting the height of the nozzle may be provided, and a separate cooling air control unit is provided to adjust the temperature and amount of the sprayed air. It may be provided additionally.

In addition, it is also possible to simultaneously control the cooling means 400 while continuously measuring the temperature of the uncoated portion Sn through a thermometer for measuring the temperature of the uncoated portion Sn, for example, a non-contact infrared thermometer.

In this way, when the temperature of the uncoated portion Sn is lowered to a predetermined range, elongation locally occurring in the uncoated portion Sn can be reduced, and accordingly, formation of wrinkles can be suppressed.

On the other hand, the binder included in the active material is a component that assists in the binding of the active material and the conductive material and the metal foil, as described above.

However, when the temperature of the metal foil increases due to heating in the drying process, the binder distributed on the contact surface with the metal foil among the binders may migrate into the coating portion Sc.

When such a movement phenomenon occurs, a defect may occur due to a decrease in adhesive strength between the active material and the metal foil. In the present invention, the cooling means 400 ), since the temperature of not only the uncoated portion (Sn) but also the entire metal foil can be lowered compared to the existing device not provided, there is also an advantage in that such a movement phenomenon can be suppressed.

Meanwhile, although not shown in the drawing, the electrode drying apparatus 1000 includes a humidity control unit for controlling the humidity in the chamber 100, a temperature sensor for measuring the temperature in the chamber 100, and a control unit for controlling the heating unit 200. may be further provided.

Hereinafter, a method of drying the electrode sheet S using the electrode drying apparatus 1000 of the present invention described above will be described.

The drying method according to the present invention includes the steps of a) putting the electrode sheet S into the chamber 100 to heat and dry it, and b) cooling the uncoated portion Sn of the electrode sheet S. .

Here, step b) maintains the temperature of the uncoated region Sn below a certain temperature by continuously supplying cool air to the uncoated region Sn from the lower part of the electrode sheet S from the start to the end of the drying of the electrode sheet S. It is a step to

Also, steps a) and steps b) may be performed simultaneously. Here, the meaning of simultaneously progressing means that the supply of cool air to the uncoated portion Sn is started at almost the same time that the electrode sheet S enters the chamber 100 .

A battery cell may be manufactured including an electrode manufactured by the above drying method, and a battery module or a battery pack may be manufactured using the battery cell.

Such a battery module or battery pack may be used as a power supply source for various devices.

As above, specific parts of the present invention have been described in detail, to those skilled in the art, these specific descriptions are only preferred embodiments, and the scope of the present invention is not limited thereby, and the scope of the present invention It is obvious to those skilled in the art that various changes and modifications are possible within the scope and scope of the technical idea, and it goes without saying that these changes and modifications fall within the scope of the appended claims.

1000: electrode drying device
100: chamber
200: heating means
300: guide roll
400: cooling means
S: electrode sheet
Sc: coating part
Sn: Uncoated region

Claims (11)

An apparatus for drying an electrode sheet including a coated portion coated with an electrode active material on a metal foil and a plain portion uncoated with the electrode active material,
a chamber in which the electrode sheet is dried;
a heating means provided in the upper part of the chamber to adjust the temperature in the chamber to a temperature for drying the electrode sheet;
a guide roll for guiding movement of the electrode sheet in front and behind the chamber and maintaining tension of the electrode sheet; and
An electrode drying apparatus comprising a cooling means for cooling the uncoated portion of the electrode sheet.
The electrode drying apparatus according to claim 1, wherein the cooling unit supplies cold air to the non-coating portion from a lower portion of the electrode sheet.
3. The electrode drying apparatus according to claim 2, wherein the cooling unit maintains the temperature of the non-coated area below a predetermined temperature by continuously supplying cold air to the uncoated area from the start to the end of drying the electrode sheet.
The electrode drying apparatus according to claim 1, wherein the heating means is any one of an infrared lamp, a heat coil, and a hot air blower.
The electrode drying apparatus according to claim 1, further comprising a humidity control unit for controlling humidity in the chamber.
[4] The electrode drying apparatus according to claim 3, further comprising a temperature sensor for measuring the temperature of the uncoated region.
A method of drying an electrode sheet using the electrode drying device of any one of claims 1 to 6,
a) putting the electrode sheet into a chamber to heat and dry it; and
b) cooling the uncoated portion of the electrode sheet;
The method of claim 7, wherein step b) is a step of continuously supplying cold air to the uncoated area from the lower part of the electrode sheet from the start to the end of drying of the electrode sheet to maintain the temperature of the uncoated area below a predetermined temperature. Characterized electrode drying method.
[Claim 9] The electrode drying method according to claim 8, wherein steps a) and steps b) are performed simultaneously.
A battery cell comprising an electrode dried using the electrode drying method according to claim 7 .
A battery module comprising the battery cell according to claim 10 .

Images