KR20240020426A - Electrode sheet coating device - Google Patents

Abstract

The present invention discloses an electrode coating device. The electrode coating device of the present invention includes: a coating unit for coating an active material on a current collector; A dryer unit that dries the active material coated on the current collector; a first heating roller disposed between the coating unit and the unwinder and heating the current collector supplied to the coating unit; and a second heating roller disposed between the dryer unit and the rewinder and heating the current collector discharged from the dryer unit.

Description

Electrode coating device {ELECTRODE SHEET COATING DEVICE}

The present invention relates to an electrode coating device that can prevent wrinkles from occurring in an electrode sheet and prevent cracks or disconnections in the electrode sheet.

Generally, secondary batteries include an anode, a cathode, and an electrolyte, and generate electrical energy using a chemical reaction. The use of secondary batteries is gradually increasing due to the advantage of being able to charge and discharge. Among such secondary batteries, lithium secondary batteries have a high energy density per unit weight, so they are widely used as a power source for electronic communication devices or as a driving source for high-output hybrid vehicles and electric vehicles.

In terms of the shape of these secondary batteries, demand is increasing for prismatic secondary batteries and pouch-shaped secondary batteries that can be applied to products such as mobile phones due to their thin thickness. In terms of secondary battery materials, demand for lithium secondary batteries such as lithium-ion batteries and lithium-ion polymer batteries with high energy density, discharge voltage, and output stability is increasing.

In these secondary batteries, an electrode assembly is accommodated inside a case. The electrode assembly is formed in a structure in which a cathode and an anode are stacked with a separator in between.

Electrodes (anode and cathode) have a structure in which an active material is applied to a current collector made of metal. Typically, the anode has a structure in which a carbon-based active material is applied to a current collector made of copper. The cathode consists of a current collector made of aluminum coated with an active material made of LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , etc. These active materials contain substances such as binders, thickeners, and solvents so that they can be easily applied to the current collector.

When manufacturing a positive or negative electrode, the active material is applied to the current collector in a coating machine. The current collector coated with the active material goes through a drying process in a dryer. When the current collector flows into the dryer, solvents such as N-methylpyrrolidone (NMP) contained in the active material are volatilized, and the solvent is volatilized from the surface of the active material layer that is in direct contact with the hot air of the dryer. The electrode sheet with the dried active material layer is wound on a rewinder.

However, conventionally, a current collector (electrode sheet) coated with an active material passes through a dryer while traveling at a constant speed. Wrinkles may occur in the uncoated area and the holding area due to thermal expansion of the current collector due to rapid temperature changes before and after the current collector passes through the dryer.

Additionally, if wrinkles occur in the holding portion, cracks or disconnection may occur in the electrode sheet. Additionally, as the adhesion of the active material decreases in the wrinkles of the holding part, dust may be generated or the active material may precipitate in the subsequent process.

Additionally, if wrinkles occur in the uncoated area, the wrinkles in the uncoated area may become worse when the current collector coated with the active material is rolled by a rolling roller. In addition, the electrode sheet may be tilted or distorted due to wrinkles in the non-coated area, which may reduce electrode folding or weldability during the slitting process.

Additionally, recently, secondary batteries have become larger or electrode sheets have been manufactured with a wider width to improve productivity, and a plurality of inner uncoated portions are formed as a plurality of lines on the inside of the electrode sheet. In this wide electrode sheet, a difference in cooling rate occurs between the holding part where the active material is applied and the uncoated part where the active material is not applied. As a difference in cooling rate occurs between the holding portion and the uncoated portion 13, the electrode sheet may be transferred in an inclined or twisted state.

Furthermore, electrode folding or weldability may deteriorate in the subsequent slitting process. Additionally, it may be difficult to accurately slit the width direction center of the uncoated portion of the electrode sheet. Therefore, the defect rate may increase in the slitting process of the electrode sheet.

Republic of Korea Patent Publication No. 2021-0144586 (published on November 30, 2021) discloses an electrode rolling device including an uncoated press portion and an electrode rolling method using the same.

The present invention was developed to solve the above-mentioned problems, and its purpose is to provide an electrode coating device that can prevent wrinkles from occurring in the electrode sheet.

The purpose of the present invention is to provide an electrode coating device that can prevent cracks in the electrode sheet or disconnection of the electrode sheet.

The purpose of the present invention is to provide an electrode coating device that can prevent the current collector from rapidly expanding thermally in the dryer unit.

The purpose of the present invention is to provide an electrode coating device that can prevent the electrode sheet from being transferred in an inclined or twisted state by maintaining a uniform cooling rate of the holding portion and the uncoated portion.

The technical problems of the present invention are not limited to the purposes mentioned above, and other purposes and advantages of the present invention that are not mentioned can be understood through the following description and will be more clearly understood by the examples of the present invention. . Additionally, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof indicated in the patent claims.

In order to solve the above problems, the electrode coating device of the present invention includes: a coating unit for coating an active material on a current collector; A dryer unit that dries the active material coated on the current collector; a first heating roller disposed between the coating unit and the unwinder and heating the current collector supplied to the coating unit; and a second heating roller disposed between the dryer unit and the rewinder and heating the current collector discharged from the dryer unit.

The first heating roller includes a first roller body portion in close contact with the current collector; and a first heater unit disposed inside the first roller body to heat the first roller body as a whole.

When the current collector includes copper, the first heating roller can heat the current collector to 45-55°C.

When the current collector includes aluminum, the first heating roller can heat the current collector to 100-120°C.

The second heating roller includes a second side heating roller that heats the side uncoated portions formed on both ends of the current collector in the width direction; And it may include a second inner heating roller that heats the inner uncoated area formed inside the width direction of the current collector.

The second side heating roller and the second inner heating roller may be formed to have the same diameter.

When the current collector includes copper, the second side heating roller and the second inner heating roller may heat the side uncoated area and the inner uncoated area to 45-55°C.

When the current collector includes aluminum, the second side heating roller and the second inner heating roller heat the side uncoated portion and the inner uncoated portion to maintain 50-60° C. when the current collector is wound on a rewinder. can do.

According to the present invention, since the current collector is preheated by the first heating roller and then supplied to the coating section, the current collector can be gradually heated in the coating section and the dryer section. Accordingly, the level of thermal expansion of the current collector due to rapid temperature changes in the dryer unit can be reduced.

According to the present invention, the current collector is prevented from rapidly expanding thermally in the dryer portion, thereby preventing wrinkles from occurring in the holding portion and the non-coating portion.

According to the present invention, since the second heating roller heats the electrode sheet discharged from the dryer unit, the electrode sheet can be cooled at a gentle rate. Accordingly, it is possible to prevent wrinkles from occurring in the electrode sheet due to rapid shrinkage.

According to the present invention, since the second heating roller eliminates the difference in cooling speed between the uncoated area and the holding area on the discharge side of the dryer unit, it is possible to prevent the electrode sheet from being wrinkled or cracked due to sudden temperature changes.

According to the present invention, it is also possible to prevent wrinkles from forming in the uncoated area and the holding area, thereby preventing meandering or twisting of the electrode sheet.

In addition to the above-described effects, specific effects of the present invention are described below while explaining specific details for carrying out the invention.

1 is a diagram schematically showing an electrode coating device according to the present invention.
FIG. 2 is a perspective view schematically showing the first heating roller of FIG. 1.
FIG. 3 is a plan view schematically showing the second heating roller of FIG. 1.
FIG. 4 is a front view schematically showing the second heating roller of FIG. 1.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention is not limited to the embodiments disclosed below, but may be subject to various changes and may be implemented in various different forms. This example is provided solely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention. Therefore, the present invention is not limited to the embodiments disclosed below, but substitutes or adds to the configuration of one embodiment and the configuration of another embodiment, as well as all changes and equivalents included in the technical spirit and scope of the present invention. It should be understood to include substitutes.

The attached drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical idea disclosed in the present specification is not limited by the attached drawings, and all changes and equivalents included in the spirit and technical scope of the present invention are not limited to the attached drawings. It should be understood to include water or substitutes. In the drawings, components may be expressed exaggeratedly large or small in size or thickness for convenience of understanding, etc., but the scope of protection of the present invention should not be construed as limited due to this.

The terms used in this specification are only used to describe specific implementations or examples, and are not intended to limit the invention. And singular expressions include plural expressions, unless the context clearly dictates otherwise. In the specification, terms such as ~include, ~consist of, etc. are intended to indicate the existence of features, numbers, steps, operations, components, parts, or a combination thereof described in the specification. In other words, terms such as ~include, ~consist, etc. in the specification. It should be understood that this does not exclude in advance the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

Terms containing ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

When a component is said to be "connected" or "connected" to another component, it is understood that it may be directly connected to or connected to the other component, but that other components may exist in between. It should be. On the other hand, when it is mentioned that a component is “directly connected” or “directly connected” to another component, it should be understood that there are no other components in between.

When a component is referred to as being "on top" or "below" another component, it should be understood that not only is it placed directly on top of the other component, but there may also be other components in between. .

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless explicitly defined in the present application, should not be interpreted in an ideal or excessively formal sense. No.

Hereinafter, an electrode coating device according to an embodiment of the present invention will be described.

Figure 1 is a diagram schematically showing an electrode coating device according to the present invention, Figure 2 is a perspective view schematically showing the first heating roller in Figure 1, and Figure 3 is a schematic diagram showing the second heating roller in Figure 1. It is a plan view, and FIG. 4 is a front view schematically showing the second heating roller of FIG. 1.

1 to 4, the electrode coating device 100 according to an embodiment of the present invention includes a coating unit 120, a dryer unit 130, a first heating roller 150, and a second heating roller 160. Includes.

The electrode sheet 10 includes a positive electrode sheet 10 and a negative electrode sheet 10. The positive electrode sheet 10 is formed by coating the inner and outer surfaces of the positive electrode current collector 10a with a positive electrode active material. In addition, the negative electrode sheet 10 is formed by coating the inner and outer surfaces of the negative electrode current collector 10 with a negative electrode active material. 1 to 4, the positive electrode sheet and the negative electrode sheet are indicated by 10, and the negative electrode current collector and positive electrode current collector are indicated by 10a.

The positive electrode active material is a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxide (LiMnO ₂ ) with the formula Li _1+x Mn _2-x O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO _{2 ,} etc.; 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 ; Nickelsite type lithium nickel _oxide ( _lithiated nickel) represented by the formula LiNi _1-x M oxide); _{Formula LiMn 2 - x M} lithium manganese complex oxide expressed as Ni, Cu or Zn); LiMn ₂ O ₄ in which part of the lithium in the chemical formula is replaced with alkaline earth metal ions; disulfide compounds; The main component may be a lithium intercalation material, such as Fe ₂ (MoO ₄ ) ₃ or a complex oxide formed by a combination thereof. There are the types of positive electrode active materials described above, but they are not limited to these.

The positive electrode current collector 10 has a thickness of, for example, 3 to 500 ㎛. The positive electrode current collector 10 is not particularly limited as long as it has conductivity without causing chemical changes in the battery. For example, the positive electrode current collector 10 may be made of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc. The electrode current collector 10 may form fine irregularities on its surface to increase the adhesion of the positive electrode active material. This electrode current collector 10 can take various forms such as film, sheet, foil, net, porous material, foam, and non-woven material.

A conductive material may be additionally mixed with the positive electrode active material particles. This conductive material is added, for example, in an amount of 1 to 50% by weight based on the total weight of the mixture including the positive electrode active material. These conductive materials are not particularly limited as long as they have high conductivity without causing chemical changes in the battery. For example, the conductive material may be 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 whiskeys such as zinc oxide and potassium titanate; Conductive oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

In addition, the negative electrode sheet 10 is manufactured by applying and drying negative electrode active material particles on the negative electrode current collector 10a, and if necessary, components such as the conductive material, binder, and solvent described above may be further included.

The negative electrode current collector 10a has a thickness of, for example, 3 to 500 ㎛. This negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical changes in the battery. For example, the negative electrode current collector 10a is made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface treated with carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy. etc. may be used. In addition, like the positive electrode current collector, the bonding power of the negative electrode active material can be strengthened by forming fine irregularities on the surface, and it can be used in various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven materials.

The negative electrode active material includes, for example, carbon such as non-graphitized carbon and graphitic carbon; Li _x Fe ₂ O ₃ (0≤x≤1), Li _x WO ₂ (0≤x≤1 _{) , Sn} Al, B, P, Si, elements of groups 1, 2, and 3 of the periodic table, halogens; metal complex oxides of 0<x≤1;1≤y≤3;1≤z≤8); lithium metal; lithium alloy; silicon-based alloy; tin-based 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 , oxides such as Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni based materials, etc. can be used.

The electrode coating device 100 has two lines of side uncoated areas 13a on which no active material is applied on both sides of the current collector 10a in the width direction, and no active material is applied on the inside of the current collector 10a in the width direction. An electrode sheet 10 in which at least one line of uncoated inner uncoated portions 13b is formed is manufactured. In addition, the electrode sheet 10 has an uncoated area 13 formed between the side uncoated area 13a and the inner uncoated area 13b. This electrode coating device manufactures a plurality of uncoated areas 13 and a wide electrode sheet 10 having the uncoated areas 13.

A wide current collector 10a in the form of a sheet is wound on the unwinder 110. The current collector 10a wound on the unwinder 110 is unwound and supplied to the coating portion 120.

The coating unit 120 is disposed between the unwinder 110 and the dryer unit 130. The coating unit 120 includes a transfer roller 121 that transfers the current collector, and a coater 123 that coats the active material on one or both sides of the contact body 10a transferred by the transfer roller 121.

At this time, when the positive electrode current collector 10a includes aluminum, an atmosphere of approximately 120° C. is formed in the coating portion 120 when the positive electrode active material is coated on the positive current collector 10a. This is because aluminum does not oxidize even when heated to about 120℃.

Additionally, when the negative electrode current collector 10a includes copper, an atmosphere of approximately 50-55° C. is formed in the coating portion 120 when the negative electrode active material is coated on the negative electrode current collector 10a. The reason is that copper has the possibility of being oxidized in the presence of oxygen at approximately 60°C.

The dryer unit 130 dries the active material coated on the current collector 10a. An atmosphere of approximately 120°C is formed inside the dryer unit 130. The dryer unit 130 may heat the current collector 10a using a heater or heat the current collector 10a using hot air. Various heating methods of the dryer unit 130 may be applied.

Additionally, a rolling roller (not shown) may be installed in the dryer unit 130 to press the active material coated on the current collector 10a onto the current collector. As the rolling roller compresses the active material to the current collector 10a, the adhesion of the active material may be improved. Additionally, the capacity of the electrode can be increased by increasing the amount of active material coated on the current collector 10a.

The first heating roller 150 is disposed between the coating unit 120 and the unwinder 110 and heats the current collector 10a supplied to the coating unit 120. The first heating roller 150 preheats the current collector 10a before the current collector is supplied to the coating unit 120. Since the current collector 10a is preheated by the first heating roller 150 and then supplied to the coating unit 120, the current collector can be gradually heated in the coating unit 120 and the dryer unit 130. Accordingly, the level of thermal expansion of the current collector 10a due to a sudden temperature change in the dryer unit 130 can be reduced. Additionally, since the current collector 10a is prevented from rapidly expanding thermally in the dryer portion 130, wrinkles can be prevented from occurring in the holding portion 11 and the uncoated portion 13.

The second heating roller 160 is disposed between the dryer unit 130 and the rewinder 140 and heats the current collector 10a discharged from the dryer unit 130. At this time, the second heating roller 160 cools the current collector 10a at a gentle rate until the current collector 10a is wound around the rewinder 140. Accordingly, it is possible to prevent wrinkles from occurring in the current collector 10a due to rapid shrinkage.

As described above, the first heating roller 150 preheats the current collector 10a on the supply side of the coating unit 120, and the second heating roller 160 cools the current collector on the discharge side of the dryer unit 130. By slowing down the speed, it is possible to prevent the current collector from being wrinkled or cracked due to sudden temperature changes. In addition, since it is possible to prevent wrinkles from forming in the holding portion 11, it is possible to prevent a decrease in the adhesion of the active material and prevent precipitation of the active material. In addition, since it is possible to prevent wrinkles from occurring in the uncoated area 13, it is possible to prevent wrinkles in the uncoated area from worsening when rolling the current collector 10a, to prevent folding of the electrode during the slitting process, and to improve weldability. It can prevent various process issues, such as degradation, from occurring.

Additionally, in the wide electrode sheet 10, the cooling rate may be substantially the same between the holding portion 11 to which the active material is applied and the uncoated portion 13 to which the active material is not applied. By maintaining the cooling rate of the holding portion 11 and the uncoated portion 13 uniformly, the electrode sheet 10 can be prevented from being transported in an inclined or distorted state.

Furthermore, it is possible to prevent electrode folding or deterioration of weldability in the subsequent slitting process. In addition, since the width direction center of the uncoated portion 13 in the electrode sheet 10 can be accurately slit, the defect rate in the slitting process of the electrode sheet 10 can be reduced.

The first heating roller 150 includes a first roller body portion 151 and a first heater portion 153. The first roller body portion 151 has a circular cross-section to be in close contact with the current collector 10a. The first heater unit 153 is disposed inside the first roller body unit 151 to heat the first roller body unit 151 as a whole. The first heater unit 153 may be installed in a circular or spiral shape inside the first roller body unit 151. This first heater unit 153 may be applied in various forms as long as it heats the first roller body unit 151 as a whole.

When the current collector 10a contains copper, the first heating roller 150 heats the current collector to 45-55°C. The reason is that copper may be oxidized in the presence of oxygen at a temperature of approximately 60°C, so it is preferable to heat the current collector 10a to a temperature lower than 60°C to prevent oxidation.

When the current collector 10a includes aluminum, the first heating roller 150 heats the current collector 10a to 100-120°C. This is because aluminum is not oxidized at a temperature of 120°C, so it may be heated to a temperature that sufficiently dries the active material coated on the current collector.

The second heating roller 160 includes a second side heating roller 161 and a second inner heating roller 163.

The second side heating roller 161 heats the side uncoated portions 13a formed at both ends of the current collector in the width direction. The second inner heating roller 163 heats the inner uncoated portion 13b formed on the inside of the current collector in the width direction. The second side heating roller 161 and the second inner heating roller 163 are formed to have the same diameter.

When the current collector 10a is discharged from the dryer portion 130, the side uncoated portion 13a is in contact with one holding portion 11, while the inner uncoated portion 13b is connected to two holding portions 11. . Accordingly, since the heat dissipation speed of the side uncoated area 13a is relatively faster than the heat dissipation speed of the inner uncoated area 13b, the heating temperature of the second side heating roller 161 is higher than that of the second inner heating roller 163. It may be heated to a slightly higher temperature than the heating temperature. In this way, the difference in cooling rates between the side uncoated area 13a and the inner uncoated area 13b can be resolved by setting the heating temperatures of the second side heating roller 161 and the second inner heating roller 163 differently.

When the current collector 10a contains copper, the second side heating roller 161 and the second inner heating roller 163 heat the side uncoated area 13a and the inner uncoated area 13b to 45-55°C. can do. Accordingly, the side uncoated area 13a and the inner uncoated area 13b are cooled at approximately the same rate as the holding part 11, thereby eliminating the difference in elongation between the holding part 11 and the uncoated area 13, thereby eliminating the uncoated area ( 13) It can prevent the occurrence of wrinkles. Additionally, since the current collector 10a is wound around the rewinder 140 while heated to a temperature slightly higher than room temperature, the current collector 10a can be cooled more slowly while wound around the rewinder 140.

When the current collector 10a includes aluminum, the second side heating roller 161 and the second inner heating roller 163 are maintained at 50-60° C. when the current collector 10a is wound on the rewinder 140. The side uncoated area 13a and the inner uncoated area 13b can be heated to do so. Accordingly, the side uncoated area 13a and the inner uncoated area 13b are cooled at approximately the same rate as the holding part 11, thereby eliminating the difference in elongation between the holding part 11 and the uncoated area 13, thereby eliminating the uncoated area ( 13) It can prevent the occurrence of wrinkles.

As described above, the present invention has been described with reference to the illustrative drawings, but the present invention is not limited to the embodiments and drawings disclosed herein, and various modifications may be made by those skilled in the art within the scope of the technical idea of the present invention. It is obvious that transformation can occur. In addition, although the operational effects according to the configuration of the present invention were not explicitly described and explained while explaining the embodiments of the present invention above, it is natural that the predictable effects due to the configuration should also be recognized.

10: Electrode sheet
10a: current collector
11: maintenance part
13: No part
13a: side plain
13b: Inner blank area
100: Coating device
110: Unwinder
120: Coating part
121: Transfer roller
123: coater
130: Dryer unit
140: Rewinder
150: First heating roller
151: First roller body part
153: First heater unit
160: Second heating roller
161: Second side heating roller
163: Second inner heating roller

Claims (8)

A coating unit that coats the current collector with an active material;
A dryer unit that dries the active material coated on the current collector;
a first heating roller disposed between the coating unit and the unwinder and heating the current collector supplied to the coating unit; and
An electrode coating device comprising; a second heating roller disposed between the dryer unit and the rewinder and heating the current collector discharged from the dryer unit. According to paragraph 1,
The first heating roller is,
a first roller body portion in close contact with the current collector; and
An electrode coating device including; a first heater unit disposed inside the first roller body to heat the first roller body as a whole. According to paragraph 1,
When the current collector includes copper, the first heating roller heats the current collector to 45-55°C. According to paragraph 1,
When the current collector includes aluminum, the first heating roller heats the current collector to 100-120°C. According to paragraph 1,
The second heating roller is,
a second side heating roller that heats the side uncoated portions formed at both ends of the current collector in the width direction; and
An electrode coating device comprising a second inner heating roller that heats an inner uncoated portion formed inside the width direction of the current collector. According to clause 5,
The electrode coating device wherein the second side heating roller and the second inner heating roller are formed to have the same diameter. According to clause 5,
When the current collector includes copper, the second side heating roller and the second inner heating roller heat the side uncoated area and the inner uncoated area to 45-55°C. According to clause 5,
When the current collector includes aluminum, the second side heating roller and the second inner heating roller heat the side uncoated portion and the inner uncoated portion to maintain 50-60° C. when the current collector is wound on a rewinder. electrode coating device.