Guide roll and electrode coating device including the same

Abstract

The present invention relates to a guide roll and an electrode coating apparatus including the same. The electrode coating apparatus according to one embodiment of the present invention includes a front coating section provided on a traveling path of a current collector for coating a front surface of the current collector with a slurry, a back coating section provided on the traveling path for coating a back surface of the current collector that has passed through the front coating section with a slurry, and a guide roll that includes a core section having a rotation axis and a surface section that surrounds the core section and is made of a material different from the core section, and transports the current collector with the back surface of the current collector facing the back coating section.

Description

[Technical field]

[0001] The present invention relates to a guide roll and an electrode coating apparatus including the same, and more particularly to a guide roll that is formed of different materials having different thermal conductivities, thereby preventing thermal deformation due to residual heat of a current collector, and an electrode coating apparatus including the same.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0061727 dated May 20, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference. [Background technology]

[0003] A lithium secondary battery has a structure in which an electrolyte containing a lithium salt is impregnated in an electrode assembly having a separator interposed between a positive electrode and a negative electrode, the positive electrode and the negative electrode being formed by applying an active material onto a current collector.

[0004] The current collector (also called "electrode substrate") is a thin metal plate that supports the electrode. Typically, the negative electrode uses copper foil as the current collector, and the positive electrode uses aluminum foil as the current collector.

[0005] In order to manufacture an electrode for a secondary battery, an active material, a conductive material, a binder, etc. may be dispersed in a solvent to prepare a slurry, and the slurry may then be applied to an electrode current collector, and the applied slurry may then be dried to form an electrode.

[0006] FIG. 1(a) is a schematic diagram showing roll 20 before thermal deformation, FIG. 1(b) is a schematic diagram showing roll 20′ after thermal deformation, and FIG. 2 is a schematic diagram for explaining the process of slurry application when a current collector is transported by the roll shown in FIG. 1(b).

[0007] The current collector is transported in a roll-to-roll manner, and an electrode sheet can be manufactured by front and back coating of the current collector 10. The current collector 10 is transported by a number of rolls 20 during the slurry coating and drying processes.

[0008] 1 and 2, during front coating of the current collector 10, the slurry applied to the front surface of the current collector 10 is dried to form a front coating layer 11. However, residual heat remains in the current collector 10 due to heat provided in the process of drying the slurry applied to the front surface of the current collector.

[0009] At this time, due to residual heat of the current collector 10, a roll 20' that transports the current collector 10 may be thermally deformed as shown in FIG. 1(b).

[0010] The roll 20' is heated by the residual heat of the current collector 10, and the faster the conveying speed of the current collector 10, the higher the temperature of the roll 20. In particular, the temperature of the central portion of the roll 20' becomes higher than the temperatures of both side ends.

[0011] Furthermore, if the transport of the current collector 10 with residual heat remaining therein is guided for a long period of time, the central portion of the roll 20' will be thermally deformed into a convex shape, as shown in FIG. 1(b).

[0012] Referring to Figure 2, when roll 20' is thermally deformed, the current collector 10 transported along the thermally deformed roll 20' also conforms to the shape of the thermally deformed roll 20', and the central portion of the current collector 10 in the width direction W of the current collector 10 protrudes in a convex shape toward the rear die coater 30.

[0013] In such a structure, when the current collector 10 is back-coated, the thickness of the slurry S applied by the back die coater 30 is not uniform along the width direction w of the current collector 10, resulting in defects in the back coating layer 12. Summary of the Invention [Problem to be solved by the invention]

[0014] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a guide roll that is surface-treated with a ceramic material to prevent thermal deformation caused by residual heat of a current collector, and an electrode coating apparatus including the same.

[0015] Another object of the present invention is to provide a guide roll having a core portion and a surface portion made of different materials, thereby increasing durability and preventing thermal deformation when guiding a current collector, and an electrode coating apparatus including the same.

[0016] Another object of the present invention is to provide a guide roll that can form a back coating layer of uniform thickness on the back surface of a current collector by guiding the current collector to a back coating process through a guide roll that does not undergo thermal deformation due to residual heat of the current collector after a front coating process of the current collector, and an electrode coating apparatus including the guide roll. [Means for solving the problem]

[0017] In order to solve the above-mentioned problems, an electrode coating apparatus according to one embodiment of the present invention includes a front coating unit that is provided on a traveling path of a current collector and that coats a front surface of the current collector with a slurry, a back coating unit that is provided on the traveling path and that coats a back surface of the current collector that has passed through the front coating unit with a slurry, and a guide roll that includes a core unit having a rotating shaft and a surface unit that surrounds the core unit and is made of a material different from that of the core unit, and that transports the current collector with the back surface of the current collector facing the back coating unit.

[0018] The surface portion may be made of a material having a lower thermal conductivity than the core portion, that is, the core portion and the surface portion may be made of different materials.

[0019] The guide roll may be provided to transport the current collector with the surface portion facing the front surface of the current collector, i.e., the guide roll may be provided to transport the current collector with the surface portion in contact with the front coating layer of the current collector.

[0020] The surface portion may be made of a ceramic material, of which various types may be used, and for example, the surface portion may include one or more of alumina or TiO2.

[0021] Also, the core part may be made of a metal material, for example, stainless steel.

[0022] Also, the surface portion may be formed by coating a surface of the core portion with a ceramic material.

[0023] In addition, the front coating unit may include a first coating unit disposed on the travel path and configured to coat a slurry on the front surface of the current collector, and a first drying unit configured to dry the slurry coated on the front surface of the current collector. As an example, the first drying unit may be configured to supply hot air to the current collector.

[0024] In addition, the back surface coating unit may include a second coating unit disposed on the travel path and configured to coat a slurry on the back surface of the current collector, and a second drying unit configured to dry the slurry coated on the back surface of the current collector. As an example, the second drying unit may be configured to supply hot air to the current collector.

[0025] In addition, the second applicator may be disposed to face a guide roll, and the second applicator may be configured to apply the slurry to a back surface of the current collector when the current collector passes through the guide roll.

[0026] Moreover, a guide roll according to one embodiment of the present invention includes a core portion having a rotation axis, and a surface portion surrounding the core portion and having a thermal conductivity different from that of the core portion.

[0027] The surface portion may be made of a material having a lower thermal conductivity than the core portion.

[0028] Also, the surface portion may be formed of a ceramic material, for example, the surface portion may include one or more of alumina or TiO2.

[0029] Also, the surface portion may be formed by coating a surface of the core portion with a ceramic material. Effect of the Invention

[0030] As described above, the guide roll and the electrode coating apparatus including the guide roll according to at least one embodiment of the present invention have the following advantages.

[0031] The guide roll is surface-treated with a material with low thermal conductivity, which can prevent thermal deformation caused by residual heat generated during front surface coating of the current collector.

[0032] In addition, by guiding the current collector to the back coating process through a guide roll, it is possible to prevent the edges of the current collector from sagging during the back coating process, and it is possible to uniformly apply the slurry along the width direction of the current collector in the back coating process.

[0033] Furthermore, by subjecting the surface of the guide roll to a surface treatment using a ceramic material, the transfer of fine electrode foreign matter to the guide roll can be reduced, and the appearance quality of the electrode sheet can be improved. [Brief description of the drawings]

[0034] [Figure 1] FIG. 2(a) is a schematic diagram showing the roll before being thermally deformed, and FIG. 2(b) is a schematic diagram showing the thermally deformed roll. [Diagram 2] FIG. 1(b) is a schematic diagram for illustrating a process in which a slurry is applied to a current collector when the current collector is transported by the rolls shown in FIG. [Diagram 3] 1 is a schematic diagram showing an electrode coating apparatus according to an embodiment of the present invention; [Figure 4] 2 shows a schematic cross section of a guide roll according to one embodiment of the present invention. [Diagram 5] 1A to 1C are diagrams illustrating a process in which a slurry is applied onto a current collector passing through guide rolls. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a guide roll and an electrode coating apparatus including the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0036] In addition, regardless of the drawing symbols, identical or corresponding components will be given the same or similar reference numbers, and duplicate descriptions thereof will be omitted, and the size and shape of each component shown for convenience of explanation may be exaggerated or reduced.

[0037] FIG. 3 is a schematic diagram showing an electrode coating apparatus according to one embodiment of the present invention, FIG. 4 is a schematic diagram showing a cross section of a guide roll according to one embodiment of the present invention, and FIG. 5 is a diagram for explaining the process of slurry being applied onto a current collector passing through the guide roll.

[0038] The electrode coating apparatus 100 according to one embodiment of the present invention includes a front coating section 110, a rear coating section 120, and a guide roll 130. The electrode coating apparatus 100 also includes a plurality of transport rolls 140 for transporting the current collector 10 so that the current collector 10 passes through the front coating section 110 and the rear coating section 120 in sequence.

[0039] The electrode coating apparatus 100 also includes a drive unit for rotating each of the transport rolls 140 and the guide rolls 130. As an example, the drive unit may include a motor.

[0040] In this specification, a current collector (also referred to as an "electrode substrate") is a thin metal plate that supports an electrode. Typically, a negative electrode uses copper foil as a current collector, and a positive electrode uses aluminum foil as a current collector.

[0041] The term electrode sheet refers to a plate-like member in which the front and back surfaces of the current collector 10 are each coated with the slurry S.

[0042] 3 and 4, the electrode coating apparatus 100 includes a front coating unit 110 provided on a travel path M of the current collector 10 for coating a slurry on a front surface of the current collector 10, and a back coating unit 120 provided on the travel path M for coating a slurry on a back surface of the current collector 10 that has passed through the front coating unit 110.

[0043] The electrode coating apparatus 100 further includes a guide roll 130 for transporting the current collector 10 with the rear surface of the current collector 10 facing the rear coating unit 120 .

[0044] The guide roll 130 includes a core portion 131 having a rotating shaft 134, and a surface portion 133 surrounding the core portion 131 and formed of a material different from that of the core portion 131. The rotating shaft 134 is connected to the driving unit described above.

[0045] The current collector 10 is transported from the front coating unit 110 to the back coating unit 120 along a travel path M. Here, the travel path M is a path along which the current collector 10 is transported along a plurality of transport rolls 140.

[0046] As the current collector 10 passes through the front coating unit 110, a slurry is applied to the front surface of the current collector 10, forming a front coating layer 11 on the front surface of the current collector 10. Then, as the current collector 10 passes through the back coating unit 120, a slurry S is applied to the back surface of the current collector 10, forming a back coating layer 12 on the back surface of the current collector 10.

[0047] The guide roll 130 is installed to transport the current collector 10 with the rear surface of the current collector 10 facing the rear coating unit 120 .

[0048] That is, since the current collector 10 passing through the guide roll 130 has passed through the front coating unit 110, residual heat remains on the current collector 10 when passing through the guide roll 130. Therefore, the guide roll 130 must not be thermally deformed by the residual heat of the current collector 10.

[0049] 4, the surface portion 133 of the guide roll 130 may be made of a material having a lower thermal conductivity than the core portion 131. That is, the core portion 131 and the surface portion 133 may be made of different materials.

[0050] In addition, the guide roll 130 may be provided to transport the current collector 10 with the surface portion 133 facing the front surface of the current collector 10. That is, the guide roll 130 may be provided to transport the current collector 10 with the surface portion 133 in contact with the front coating layer 11 of the current collector 10.

[0051] Also, the surface portion 133 may be made of a ceramic material. Various types of ceramic materials may be used, and for example, the surface portion 133 may include one or more of alumina or TiO2.

[0052] In addition, the core part 131 may be made of a metal material, for example, stainless steel. By forming the guide roll 130 from different materials in this manner, it is possible to increase durability and prevent thermal deformation when guiding the current collector 10.

[0053] Also, the surface portion 133 may be formed by coating the surface of the core portion 131 with a ceramic material.

[0054] In addition, the front coating unit 110 may include a first coating unit 111 arranged on the traveling path M for coating a slurry on the front surface of the current collector 10, and a first drying unit 115 for drying the slurry coated on the front surface of the current collector 10.

[0055] In addition, the rear coating unit 120 may include a second coating unit 121 arranged on the traveling path M for coating a slurry S onto the rear surface of the current collector 10, and a second drying unit 125 for drying the slurry coated on the rear surface of the current collector 10.

[0056] 3 and 5, guide roll 130 is provided facing second coating section 121. Guide roll 130 guides the transport of current collector 10 while rotating. That is, guide roll 130, together with multiple transport rolls 140, forms a travel path for current collector 10.

[0057] Further, the guide roll 130 guides the transport of the current collector 10 so that the back surface of the current collector 10 faces the back surface coating section 120 .

[0058] When the second coating unit 121 coats the slurry S, the guide roll 130 supports the current collector 10 in the width direction of the current collector 10. Specifically, the guide roll 130 is provided opposite the second coating unit 121 across the current collector 10, and guides the transportation of the current collector 10 so that the slurry S coated by the second coating unit 121 is uniformly coated in the width direction of the current collector 10.

[0059] Referring to FIG. 4, the guide roll 130 includes a core portion 131 and a surface portion 133 .

[0060] The core portion 131 may have a cylindrical shape with a circular cross section. The core portion 131 has a length greater than the width w of the current collector 10. The core portion 131 is rotatably provided on the travel path M, and guides the transport of the current collector 10 along the travel path.

[0061] The surface portion 133 is provided so as to surround the core portion 131. The surface portion 133 has a thermal conductivity different from that of the core portion 131.

[0062] The surface portion 133 is made of a material having a lower thermal conductivity than that of the core portion 131, and is formed by surface-treating the core portion 131. As an example, the surface portion 133 is made of a ceramic material.

[0063] In such a structure, the guide roll 130 has a lower thermal conductivity in the surface portion 133 than in the core portion 131, and can prevent thermal deformation due to residual heat of the current collector 10 that has passed through the front coating process.

[0064] In addition, the guide roll 130, which does not deform due to residual heat of the current collector 10, guides the current collector 10 to the back coating process, thereby preventing the current collector 10 from sagging to both sides of the guide roll 130 based on the center of the guide roll 130.

[0065] Referring to FIG. 5, when the second coating unit 121 coats the slurry S, the slurry S may be uniformly coated on the rear surface of the current collector 10 along the width direction of the current collector 10 .

[0066] In addition, the front coating unit 110 applies the slurry S to the front surface of the current collector 10 and dries it, thereby performing a front coating process on the front surface of the current collector 10. The front coating unit 110 includes a first application unit 111 and a first drying unit 115.

[0067] The front surface coating step proceeds while the current collector 10 passes through the first coating section 111 and the first drying section 115 along the travel path M in this order.

[0068] First coating section 111 is provided on travel path M of current collector 10, and coats the front surface of current collector 10 with slurry. Current collector 10 with the slurry coated on its front surface enters first drying section 115.

[0069] Here, the slurry is a mixture of an active material, a binder, a conductive material, and a solvent. The active material may be a positive electrode active material or a negative electrode active material. The binder may be a polymer additive for stabilizing the structure of the electrode, and the conductive material may be a carbon-based additive for improving the conductivity.

[0070] The first drying section 115 is provided on the outlet side of the first coating section 111. The first drying section 115 can provide hot air to the current collector 10 according to preset temperature conditions. The current collector 10 is heated and dried while passing through the first drying section 115.

[0071] In the drying process of the first drying section 115, while the water in the slurry applied to the front surface of the current collector 10 is dried, the components contained in the slurry S are coated on the front surface of the current collector 10 to form a front coating layer 11. The front coating layer 11 refers to a coating layer provided on the front surface of the current collector 10.

[0072] After the front coating step, the current collector 10 is transported along a plurality of transport rolls 140 and guide rolls 130 and enters the back coating section 120 .

[0073] The back surface coating unit 120 applies the slurry S to the back surface of the current collector 10 and dries it, thereby performing a back surface coating process on the back surface of the current collector 10. The back surface coating unit 120 includes a second application unit 121 and a second drying unit 125.

[0074] The back surface coating process proceeds while the current collector 10 passes through the second coating section 121 and the second drying section 125 in sequence along the travel path M.

[0075] The second applicator 121 is provided in the travel path M of the current collector 10 so as to face the guide roll 130 with the current collector 10 therebetween. The second applicator 121 applies the slurry S to the back surface of the current collector 10.

[0076] The second coating unit 121 coats the rear surface of the current collector 10 with the slurry S along the width direction of the current collector 10 while the current collector 10 passes through the guide roll 130. The second coating unit 121 differs from the first coating unit 111 only in its installation position, and the type and coating method of the slurry S coated on the current collector 10 may be the same.

[0077] The second drying section 125 is provided on the travel path from the direction of the outlet side of the second coating section 121. The second drying section 125 provides hot air to the current collector 10. The current collector 10 is heated and dried while passing through the second drying section 125.

[0078] In the drying process in the second drying section 125, while the water in the slurry S applied to the back surface of the current collector is dried, the components contained in the slurry S are coated on the back surface of the current collector 10 to form a back coating layer 12. The back coating layer 12 refers to a coating layer on the back surface of the current collector 10.

[0079] The above-described embodiment of the present invention has been disclosed for illustrative purposes, and a person skilled in the art having ordinary knowledge of the present invention may make various modifications, changes, and additions within the spirit and scope of the present invention, and such modifications, changes, and additions should be considered to fall within the scope of the following claims. [Industrial Applicability]

[0080] According to at least one embodiment of the guide roll and the electrode coating apparatus including the same according to the present invention, the guide roll is surface-treated with a material having low thermal conductivity, thereby preventing thermal deformation due to residual heat generated during front surface coating of the current collector. [Explanation of symbols]

[0081] 10 Current collector 11 Front coating layer 12 Back coating layer 20,20' roll 100 Electrode Coating Equipment 110 Front coating part 111 First application section 115 1st drying section 120 Back coating section 121 Second application section 125 2nd drying section 130 Guide Roll 131 Core 133 Surface part 134 Rotational Axis 140 Transport roll

Claims

1. a front coating unit provided on a travel path of the current collector for coating a front surface of the current collector with a slurry; a back coating section provided on the travel path for coating a slurry on a back surface of the current collector that has passed through the front coating section; an electrode coating device comprising: a core portion having a rotation axis; and a surface portion surrounding the core portion and formed of a material different from that of the core portion; and a guide roll that transports the current collector with the back surface of the current collector facing the back surface coating portion.

2. 2. The electrode coating device according to claim 1, wherein the surface portion is formed of a material having a thermal conductivity lower than that of the core portion.

3. 3. The electrode coating apparatus according to claim 2, wherein the guide roll transports the current collector with the surface portion facing the front surface of the current collector.

4. 4. The electrode coating device according to claim 2, wherein the surface portion is made of a ceramic material.

5. The electrode coating device according to claim 2 , wherein the core portion is made of a metal material.

6. 5. The electrode coating device according to claim 4, wherein the surface portion is formed by coating a surface of a core portion with a ceramic material.

7. The surface portion is made of alumina or TiO ２ 3. The electrode coating apparatus of claim 2, comprising one or more of:

8. the front surface coating unit is a first coating unit disposed on the travel path and configured to coat a slurry on a front surface of the current collector; The electrode coating apparatus according to claim 1 , further comprising: a first drying section for drying the slurry applied to the front surface of the current collector.

9. the back surface coating unit is a second coating unit disposed on the travel path and configured to coat a slurry on a back surface of the current collector; The electrode coating apparatus according to claim 1 , further comprising: a second drying section for drying the slurry applied to the back surface of the current collector.

10. The second coating unit is disposed to face a guide roll, The electrode coating apparatus according to claim 9 , wherein the second applicator is provided to apply the slurry to the back surface of the current collector when the current collector passes through the guide roll.

11. A core portion having a rotation axis; a surface portion surrounding the core portion and having a thermal conductivity different from that of the core portion.

12. The guide roll according to claim 11 , wherein the surface portion is formed of a material having a thermal conductivity lower than that of the core portion.

13. The guide roll according to claim 11 or 12, wherein the surface portion is made of a ceramic material.

14. The surface portion is made of alumina or TiO ２ The guide roll of claim 11 , comprising one or more of:

15. The guide roll according to claim 11, wherein the surface portion is formed by coating a surface of a core portion with a ceramic material.

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