Apparatus and method for roll-pressing electrode sheets and electrode sheets manufactured by the method

Abstract

An apparatus for roll-pressing an electrode sheet is provided, in which the electrode sheet has a coated portion located in the middle along a width thereof and extending in a length direction thereof, and uncoated portions located on both sides of the coated portion, respectively. The apparatus includes a stage for placing the electrode sheet, and a tab press roller configured to roll-press on one of the uncoated portions of the electrode sheet to perform a pressing process, in which the tab press roller is configured to form a preset angle with respect to the stage during the pressing process, such that the tab press roller applies a smaller pressure on a side of the uncoated portion closer to the coated portion than on the other side farther from the coated portion.

Description

Technical Field

[0001] The present invention relates to apparatus and method for rolling electrode sheets and electrode sheets manufactured by the method.

[0002] More specifically, the present invention relates to an apparatus for rolling electrode sheets, which is capable of preventing damage to the electrode sheets during the rolling process, and more specifically, during the bonding pressing process.

[0003] The present invention also relates to a method for rolling electrode sheets, according to which damage to the electrode sheets due to applied pressure can be prevented during the rolling process of the electrode sheets, and more specifically, during the bonding pressing process.

[0004] Furthermore, the present invention relates to an electrode sheet manufactured by a method for rolling electrode sheets, according to which potential damage that may be caused by applied pressure during the bonding pressing process of the electrode sheet is avoided. Background Technology

[0005] Secondary batteries (commonly known as rechargeable batteries) can be discharged through use and then restored to their original state through charging. They have recently been widely used as a power source for wireless devices such as personal digital devices, mobile phones, or laptops. Furthermore, secondary batteries have gained attention as a power source for electric vehicles, hybrid electric vehicles, and other vehicles considered a solution to the air pollution problems caused by conventional gasoline or diesel vehicles using fossil fuels. Due to their significant advantages over other conventional energy sources, the applications of secondary batteries are becoming increasingly widespread, and consumer demand for them is also increasing.

[0006] Among various rechargeable batteries, lithium-ion batteries are particularly widely used as an energy source for various electronic products because they exhibit high energy density, high operating voltage, and excellent storage and lifespan characteristics.

[0007] With the expansion of applications for secondary batteries, the demand for higher-capacity secondary batteries is rapidly increasing. As a method to increase the capacity of secondary batteries, techniques for increasing the loading of the electrode mixture layer are being researched. However, increasing the loading of the electrode mixture layer leads to an increase in the volume of the electrode sheet. To reduce the volume of the electrode sheet, a process of rolling the electrode sheet at higher pressure is required. However, during the high-pressure rolling process, defects may appear on the sides of the electrode sheet.

[0008] Therefore, it would be beneficial to develop a technology that can solve the above-mentioned technical problems by preventing or reducing damage to the uncoated portions of the electrode sheets during the pressing process using a sheet-jointing roller. Summary of the Invention

[0009] [Technical Issues]

[0010] In view of the aforementioned problems in the related art, the present invention has been made. One object of the present invention is to provide an apparatus and method for rolling electrode sheets, which can prevent the electrode sheets from being damaged during the pressing process, especially due to pressure applied to the uncoated portions of the electrode sheets.

[0011] [Technical Solution]

[0012] One aspect of the invention relates to an apparatus for rolling an electrode sheet. The electrode sheet may have a coated portion located in the middle of its width and extending along its length, and uncoated portions located on either side of the coated portion. The apparatus includes a platform for placing the electrode sheet. The apparatus may also include a receiving roller configured to roll over an uncoated portion of the electrode sheet to perform a pressing process. Furthermore, the receiving roller may be configured to form a predetermined angle relative to the platform during the pressing process, such that the receiving roller applies less pressure on the side of the uncoated portion closer to the coated portion than on the side farther from the coated portion.

[0013] Therefore, by applying a small amount of pressure to the portion of the uncoated portion adjacent to the coated portion, the present invention can prevent or reduce damage when bonding is performed on the uncoated portion of the electrode sheet.

[0014] The electrode sheet rolled by this equipment can have a structure in which an electrode mixture layer is coated on one or both sides of a current collector layer. Specifically, the electrode mixture layer can be a slurry containing active materials, binders, and solvents, wherein the active materials are components that undergo electrochemical reactions during charge and discharge cycles in a secondary battery to store and release energy. The current collector layer can be a thin metal foil designed to conduct current between the electrochemical active materials and the external circuitry of the battery.

[0015] During the process of coating the electrode mixture onto the current collector layer, the electrode mixture layer can be coated onto the current collector layer in a desired area and at a desired thickness. The coated portion can be located in the middle of the electrode sheet along its width and extend in its length direction, while the uncoated portion can be located on either side of the coated portion, for example. For example, the slurry can be uniformly spread on the surface of the current collector layer by a blade, or the slurry can be extruded onto the moving current collector layer by a slot die, such that the coated portion extends longitudinally along the direction of the moving current collector layer. However, the coating method is not limited to these. The current collector can be immersed in the slurry and then removed at a controlled speed. Alternatively, the slurry can be atomized and sprayed onto the current collector.

[0016] After the electrode mixture layer is coated onto the current collector layer, rolling can be performed on the electrode sheet to increase the density of the coated electrode mixture layer. This process is often referred to as a drying and pressing process. This process reduces the thickness of the electrode sheet to achieve the desired density, which enhances the energy density and mechanical integrity of the electrode sheet. For example, a heavy roller with a heater can be used to press the electrode sheet. During this process, pressure is applied to the electrode sheet by the heavy roller.

[0017] Equipment for drying and pressing may include hot-pressing rollers and a platform for supporting the electrode sheet, allowing the rollers to roll over the electrode sheet and perform the drying and pressing process. However, instead of a platform, the rollers may be arranged in pairs, rotating relative to each other, with the electrode sheet sandwiched between them. During the pressing process, where the electrode sheet is pressed under high pressure by the rollers, expansion may occur on the sides of the electrode sheet, particularly in the uncoated portions, leading to an increased rate of process defects. To prevent this, the pressing process employs one or more pressing rollers to roll over the uncoated portions. The uncoated portions of the electrode sheet are pressed by a pair of pressing rollers positioned on two sides of the coated portion of the electrode sheet.

[0018] In this device, a preset angle greater than zero degrees can be determined such that the boundary of the contact surface between the bonding roller and the uncoated portion closest to the uncoated portion remains in contact during bonding pressing. During bonding pressing, the relative boundary of the contact surface between the bonding roller and the uncoated portion furthest from the coated portion can be slightly below the upper surface of the platform because this part of the platform elastically deforms due to the downward pressure applied by the bonding roller.

[0019] According to an embodiment of the present invention, the sheet-jointing pressure roller may have a truncated cone shape.

[0020] For example, the splicing roller can have the shape of a conical segment or a pyramid, without a vertex and terminating in a plane parallel to its base. The base of the truncated cone shape is perpendicular to the roller axis of the splicing roller. The central roller axis of the splicing roller can be set parallel to the platform. The splicing roller forms a predetermined angle relative to the platform due to its external shape, while keeping its roller axis parallel to the platform.

[0021] According to an embodiment of the present invention, the sheet-attaching pressure roller may have a cylindrical shape and may be configured to be applied to the electrode sheet during pressing while maintaining a preset angle relative to the platform.

[0022] For example, during pressing (i.e., bonding pressing), the curved surface of the bonding roller can be applied to the uncoated portion of the electrode sheet while maintaining a preset angle.

[0023] According to an embodiment of the invention, the side of the sheet-jointing roller closest to the coating portion during the pressing process can be rounded or chamfered.

[0024] Therefore, the above-described structure of the splicing roller prevents the uncoated portion from being damaged due to the abrupt pressure difference at the boundary of the contact surface between the splicing roller and the uncoated portion of the adjacent coated portion.

[0025] According to an embodiment of the present invention, the surface of the contact roller that contacts the electrode sheet during the pressing process may have a raised or recessed pattern.

[0026] For example, the depth of the pattern transferred onto the uncoated portion by the embossing is less than the height of the embossing itself. In this case, a preset angle between the curved surface of the bonding roller and the platform can be determined based on the length of the curved surface of the bonding roller and the height of the embossing. In this way, the boundary of the contact surface between the bonding roller and the uncoated portion closest to the coated portion can remain in contact during bonding.

[0027] According to an embodiment of the invention, the device may further include another bonding roller for bonding and pressing the uncoated portion of the electrode sheet from the opposite side of the bonding roller. Here, the bonding roller and the other bonding roller may be configured to engage with each other, with the electrode sheet placed between the bonding roller and the other bonding roller.

[0028] Therefore, it can be advantageous to use a combination of top and bottom contact rollers on the top and bottom surfaces of the electrode sheet, especially when both surfaces are coated with an electrode mixture layer. However, the use of top and bottom contact rollers is not limited to such double-sided coated electrode sheets.

[0029] According to an embodiment of the invention, another lamination roller can be configured to form a predetermined angle relative to the platform during the pressing process. The other lamination roller can apply less pressure on the side of the uncoated portion closer to the coated portion than on the side farther from the coated portion.

[0030] Another aspect of the invention relates to a method for rolling an electrode sheet. The electrode sheet may have a coated portion located in the middle of its width and extending along its length, and uncoated portions located on either side of the coated portion. The method may include placing the electrode sheet on a platform. The method may further include rolling an uncoated portion of the electrode sheet by a pressing roller to perform a pressing process. According to the invention, during the pressing process, the pressing roller may be applied to the electrode sheet while forming a predetermined angle relative to the platform, such that the pressing roller applies less pressure on the side of the uncoated portion closer to the coated portion than on the side farther from the coated portion.

[0031] According to an embodiment of the invention, the electrode pressing roller may have a truncated cone shape, and during the pressing process, the electrode pressing roller may be applied to the electrode sheet, and its axis of rotation is parallel to the platform.

[0032] According to an embodiment of the present invention, the electrode pressing roller may have a cylindrical shape, and during the pressing process, the electrode pressing roller may be applied to the electrode sheet, and its rotation axis maintains a preset angle relative to the platform.

[0033] According to an embodiment of the present invention, during the pressing process, the sheet-attaching roller can impart a raised or recessed pattern on the uncoated portion of the electrode sheet.

[0034] According to an embodiment of the present invention, the method may further include: rolling an uncoated portion of the electrode sheet using another bonding roller from the opposite side of the bonding roller to perform a pressing process. Here, the bonding roller and the other bonding roller may be engaged with each other, and the electrode sheet is placed between the bonding roller and the other bonding roller.

[0035] According to an embodiment of the invention, during the pressing process, another contact roller can be applied to the electrode sheet while forming a predetermined angle relative to the platform. The other contact roller can apply less pressure on the side of the uncoated portion closer to the coated portion than on the side farther from the coated portion.

[0036] According to another aspect of the invention, an electrode sheet manufactured by a method for rolling an electrode sheet is provided. The electrode sheet may have a coated portion located in the middle of its width and extending in its length direction, and uncoated portions located on both sides of the coated portion. The electrode sheet includes tabs formed from the uncoated portions, which have undergone a pressing process. Preferably, the tabs do not have a line pattern extending in their width direction and dividing one side of the tab with a certain height.

[0037] According to an embodiment of the invention, the contact patch may have a pattern formed on its surface, the pattern having a continuously varying depth depending on the distance from the coated portion of the electrode patch.

[0038] According to an embodiment of the invention, the depth of the pattern is shallower in the portion closer to the coated portion than in the portion farther away from the coated portion 120.

[0039] [Beneficial Effects]

[0040] When the electrode sheet is rolled using the device according to the invention, damage can be prevented or reduced because a smaller pressure is applied to the side of the uncoated portion during the pressing process. Attached Figure Description

[0041] To gain a more complete understanding of the invention and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings. The invention is explained in more detail below using exemplary embodiments specified in the schematic diagrams of the drawings, wherein:

[0042] Figure 1A schematic plan view of a rolled electrode sheet according to the relevant technology is shown.

[0043] Figure 2 A schematic cross-sectional view of a rolled electrode sheet according to the related technology is shown from the side.

[0044] Figure 3 The image shows a photograph of an electrode sheet damaged during pressing processing using equipment based on related technology.

[0045] Figure 4 This is a schematic diagram of an apparatus for rolling electrode sheets according to an embodiment of the present invention.

[0046] Figure 5 (a) and (b) are respectively based on Figure 4 Enlarged partial views of two variations of the bonding roller that presses the uncoated portion of the electrode sheet according to the embodiment.

[0047] Figure 6 It is based on Figure 4 and Figure 5 A cross-sectional view taken along the A-A' direction of the bonding roller that presses the uncoated portion of the embodiment.

[0048] Figure 7 (a) and (b) are schematic diagrams of two variations of a bonding roller for bonding uncoated portions according to another embodiment of the present invention.

[0049] Figure 8 This is a schematic cross-sectional view of a splicing roller for an uncoated portion according to another embodiment of the present invention.

[0050] Figure 9 A cross-sectional view from the side is schematically shown of an apparatus for rolling electrode sheets according to an embodiment of the present invention.

[0051] Figure 10 (A) to (C) are schematic diagrams of an apparatus for rolling electrode sheets according to an embodiment of the present invention. Detailed Implementation

[0052] The terms or words used in this specification and claims should not be construed as having a general meaning or dictionary-based meaning, but should be interpreted as having a meaning and concept consistent with the technical spirit of the invention in the broadest possible way.

[0053] In this disclosure, it should be understood that the terms "comprising," "including," "having," etc., specify the presence of the stated features, numbers, steps, operations, elements, components, or combinations thereof, but do not exclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations thereof.

[0054] Furthermore, when a portion such as a layer, membrane, region, or plate is referred to as being "on" another portion, this includes not only the case where the portion is "directly" "on" the other portion, but also the case where another portion is inserted between them. Conversely, when a portion such as a layer, membrane, region, or plate is referred to as being "below" another portion, this includes not only the case where the portion is "directly" "below" the other portion, but also the case where another portion is inserted between them. Additionally, in this disclosure, "above" can include both lower and upper portions.

[0055] Terms such as “first” and “second” may be used to describe various components, but components should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the invention, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component. Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0056] Furthermore, the same reference numerals are used throughout the drawings to refer to parts that perform similar functions or operations. In this disclosure, where one part is referred to as being connected to another part, not only can one part be directly connected to another part, but one part can also be indirectly connected to another part via yet another part. Moreover, including an element does not imply the exclusion of other elements, but rather means that these elements may be further included, unless otherwise specified.

[0057] The apparatus and method for rolling electrode sheets according to the present invention will be described in detail below with reference to the accompanying drawings.

[0058] The electrode sheet 100 may have a structure in which the electrode mixture layer is coated on one or both sides of the current collector layer.

[0059] The electrode mixture layer can be a slurry containing active materials, a binder, and a solvent, where the binder helps to hold the active material particles together and adhere them to the current collector layer. Active materials are components that undergo electrochemical reactions to store and release energy during the charge and discharge cycles of a secondary battery. For example, one or more of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, nickel manganese, and nickel cobalt aluminum oxide can be used as cathode active materials. For example, one or more of graphite, lithium titanate, and silicon-based materials can be used as anode active materials.

[0060] The current collector layer can be a thin metal foil designed to conduct current between the electrochemical active material and the external circuitry of the battery. For example, an aluminum layer can be used for the cathode current collector, and a copper layer can be used for the anode current collector. Additional coatings can be applied to the current collector layer to improve adhesion to the active material, enhance corrosion resistance, or reduce resistance.

[0061] An electrode mixture layer can be coated onto a current collector layer at a desired thickness in a desired area. The coated portion can be located in the middle of the electrode sheet along its width, while uncoated portions can be located on either side of the coated portion. Various methods can be used in the coating process. For example, the slurry can be uniformly spread onto the surface of the current collector layer using blades. The slurry can be extruded onto a moving current collector layer using a slot die. The current collector can be immersed in the slurry and then removed at a controlled speed. Alternatively, the slurry can be atomized and sprayed onto the current collector.

[0062] After the electrode mixture layer is coated onto the current collector layer, a process is performed to increase the density of the coated electrode mixture layer; this process is commonly referred to as a drying and pressing process. This process reduces the thickness of the electrode sheet to achieve the desired density, which enhances the energy density and mechanical integrity of the electrode sheet. For example, a heavy roller with a heater can be used to press the electrode sheet. During this process, pressure is applied to the electrode sheet by the heavy roller.

[0063] The apparatus for drying and pressing may include a hot-pressing roller and a platform for supporting the electrode sheet, such that the roller can press the electrode sheet and perform the drying and pressing process. However, instead of a platform, the rollers may be arranged in a pair, such that the pair of rollers rotate relative to each other, with the electrode sheet sandwiched between the pair of rollers.

[0064] Figure 1 and Figure 2 This is a schematic diagram illustrating the pressing process of an electrode sheet according to related technologies. (Reference) Figure 1 and Figure 2 The electrode sheet 100 undergoes a pressing process as it passes through the pressure roller 11. The electrode sheet 100 has a structure in which an electrode mixture layer is coated on the surface of a current collector layer made of aluminum foil. Through the pressing process of the electrode sheet 100, the density of the electrode mixture layer increases while its volume decreases. However, during the pressing process of the electrode sheet 100 under high pressure by passing through the pressure roller 11, expansion may occur on the sides of the electrode sheet 100, particularly in its uncoated portion 110, leading to an increase in the process defect rate.

[0065] To prevent this situation, such as Figure 1 and Figure 2 As shown, the pressing process uses one or more sheet-jointing pressure rollers 12(a) and 12(b) to press the uncoated portion 110. The uncoated portion 110 of the electrode sheet 100 is pressed by a pair of sheet-jointing pressure rollers 12(a) and 12(b) respectively disposed on two sides of the coated portion 120 of the electrode sheet.

[0066] However, when the uncoated portion 110 is pressed by the bonding rollers 12(a) and 12(b), accidental damage may occur on the side of the uncoated portion 110 near the coated portion 120, at the position that has already come into contact with the outermost circumference of the bonding roller 12 during the bonding pressing process. Figure 3 An example of an uncoated portion of an electrode sheet damaged by the electrode pressing roller during the electrode pressing process is shown.

[0067] Figure 4 An apparatus 20 for rolling electrode sheets 100 according to one embodiment of the present invention is shown schematically.

[0068] Electrode sheet 100 may include a coated portion 120 located in the middle of its width and extending along its length, and uncoated portions 110 located on both sides of the coated portion 120. Figure 4 (Only one side is shown in the image). The electrode sheet 100 may have a coating portion 120 on one surface or on both the top and bottom surfaces. The electrode sheet 100 is disposed on the platform 23, which will be described in detail below.

[0069] The rolling equipment 20 may include a roller (not shown) for rolling the central portion (i.e., the coated portion 120) of the electrode sheet 100. Furthermore, the rolling equipment 20 of this embodiment may include a bonding roller 22 configured to roll over the uncoated portion 110 of the electrode sheet 100 to perform a bonding pressing process. The bonding rollers 22 may be arranged in pairs, located on opposite sides of the coated portion 120 for the respective uncoated portions 110. For example, the rolling equipment 20 includes a platform 23 on which the electrode sheet 100 is placed to undergo a pressing process. The platform 23 is formed of a material with a degree of elasticity, allowing it to deform during the pressing process according to the movement of the overhead roller and the bonding roller 22.

[0070] However, the present invention is not limited to the above-described configuration including platform 23 and pressure rollers and bonding rollers 22 arranged on platform 23 to perform rolling and bonding pressing respectively. For example, pressure rollers for rolling the center portion can be configured as a pair, one located above the coated portion 120 of electrode sheet 100 and the other located below the coated portion 120 of electrode sheet 100. The pair of pressure rollers can roll relative to each other, with the uncoated portion 120 of electrode sheet 100 sandwiched between the pair of pressure rollers. In this embodiment, the platform 23 described above is not required. Additionally or alternatively, bonding rollers 22 for rolling the periphery (uncoated portion) of electrode sheet 100 can be configured as a pair, one located above the uncoated portion 110 and the other located below the uncoated portion 110. A pair of bonding rollers 22 can roll relative to each other, with the uncoated portion 110 sandwiched between the pair of bonding rollers. In this case, platform 23 is not needed, or the size of platform 23 can be reduced so that only the coated portion 120 of electrode sheet 100 can be placed on platform 23, while the uncoated portion 110 is outside the range of platform 23.

[0071] The rolling apparatus 20 of this embodiment includes a configuration for applying a smaller pressure on the side of the uncoated portion 110 closer to the coated portion 120 than on the other side farther from the coated portion 120. Due to this configuration, during the pressing process, a smaller pressure is applied to the side of the uncoated portion 110 closer to the coated portion 120. Therefore, when bonding pressing is performed on the uncoated portion of the electrode sheet using the apparatus according to the invention, damage can be prevented or reduced.

[0072] according to Figure 5 In (a), the cylindrical contact roller 22 is positioned to form a preset angle θ1 relative to the platform 23. During the pressing process (i.e., contact pressing), the curved surface of the contact roller 22 is applied to the uncoated portion 110 of the electrode sheet 100 while maintaining the preset angle θ1. This configuration prevents damage to the uncoated portion 110 due to abrupt pressure differences at the boundary of the contact surface between the contact roller 22 and the uncoated portion 110 closest to the coated portion 120. The preset angle θ1 can be determined such that the boundary of the contact surface between the contact roller 22 and the uncoated portion 110 closest to the coated portion 120 remains in contact during contact pressing. In other words, contact between the contact roller 22 and the uncoated portion 110 needs to be maintained across the entire width of the contact roller 22. When the bonding pressing is performed, the relative boundary of the contact surface between the bonding roller 22 and the uncoated portion 110 furthest from the coated portion 120 is slightly below the upper surface of the platform 23, because this portion of the platform 23 is elastically deformed due to the downward pressure applied by the bonding roller 22.

[0073] like Figure 6As shown, the bonding roller 22 may also have an embossed pattern on its curved surface. According to 5(b), the depth of the pattern transferred to the uncoated portion 110 by the embossed pattern is less than the height H of the embossed pattern itself. In this case, a preset angle θ2 between the curved surface of the bonding roller 22 and the platform 23 can be determined based on the length L of the curved surface of the bonding roller 22 and the height H (or depth) of the embossed pattern. The maximum value of the preset angle θ2 can be calculated as the height H divided by the arctangent of the length L, as shown in the following formula.

[0074] θ2=tan -1 (H / L),

[0075] H: Pattern height, L: Length / width of the curved surface of the splicing roller

[0076] In this way, the boundary of the contact surface between the bonding roller 22 and the uncoated portion 110 closest to the coated portion 120 can remain in contact during bonding. For example, if the length L is 15 mm and the pattern height H is 1 mm, the preset angle θ2 can be set to no more than 3.8 degrees.

[0077] The material of the electrode bonding roller 22 can be selected from any material with a certain degree of elasticity, as long as it can achieve the above-mentioned purpose without damaging the uncoated portion of the electrode sheet. For example, the electrode bonding roller 22 can be made of polyurethane.

[0078] Figure 7 (a) schematically illustrates a snap-fit ​​roller 32 according to another embodiment of the invention, which has a truncated conical shape. For example, the snap-fit ​​roller 32 has the shape of a conical segment or pyramid, without a vertex and terminating in a plane parallel to the base. The base of the truncated conical shape is perpendicular to the roller axis of the snap-fit ​​roller 32. In this embodiment, the central roller axis of the snap-fit ​​roller 32 may be arranged parallel to the platform 23. However, the snap-fit ​​roller 32 forms a predetermined angle θ3 relative to the platform 23 due to its external shape, while keeping its roller axis parallel to the platform 23.

[0079] A preset angle θ3 can be determined such that the boundary of the contact surface between the bonding roller 32 and the uncoated portion 110 closest to the coated portion 120 remains in contact. In other words, contact between the bonding roller 32 and the uncoated portion 110 needs to be maintained across the entire width of the bonding roller 32. During bonding pressing, the relative boundary of the contact surface between the bonding roller 32 and the uncoated portion 110 furthest from the coated portion 120 is slightly below the upper surface of the platform 23 because this portion of the platform 23 elastically deforms due to the downward pressure applied by the bonding roller 32.

[0080] and Figure 6Similarly, the curved surface of the truncated cone-shaped contact roller 32 that contacts the electrode sheet 100 (more precisely, the uncoated portion) during the contact pressing process may also have an embossed pattern. The truncated cone-shaped contact roller 32 may preferably be made of polyurethane.

[0081] Reference Figure 7 (b) The preset angle θ4 of the truncated conical contact roller 32 with the embossed pattern can be set by taking into account the length or width L of the contact roller 32 and the height or depth H of the embossed pattern. The maximum value of the preset angle θ4 can be calculated as the arctangent of the height H divided by the length L, as shown in the following formula.

[0082] θ2=tan -1 (H / L),

[0083] H: Pattern height, L: Length / width of the curved surface of the splicing roller

[0084] For example, if the length L of the bonding roller 32 is 15mm and the pattern height H is 1mm, then the preset angle θ4 can be set to no more than 3.8 degrees.

[0085] Figure 8 A bonding roller 42 for bonding and pressing an uncoated portion of an electrode sheet according to another embodiment of the present invention is schematically shown. According to this embodiment, the bonding roller 42 may have rounded or chamfered portions 41 at its edges and / or corners in contact with the electrode sheet. The rounded or chamfered portions 41 of the bonding roller 42 can prevent or reduce damage caused by abrupt pressure differences at the boundary between the bonding roller 42 and the uncoated portion 110 closest to the coated portion 120. The radius of curvature of the rounded portion 41 may be approximately 1 mm. The bonding roller 42 of this embodiment may have a cylindrical shape, a truncated cone shape, or any other shape, as long as the bonding roller 42 has rounded or chamfered portions 41 at its edges and / or corners and can achieve the above-described function without damaging the uncoated portion of the electrode sheet.

[0086] According to an embodiment of the present invention, see Figure 9 and Figure 10 A second bonding roller 52, used for bonding the uncoated portion of the electrode sheet 110 from the bottom surface of the electrode sheet, may be additionally provided below the platform 23. The second bonding roller 52 may be positioned opposite any of the bonding rollers 22, 32, and 42 located on the top surface of the electrode sheet 100, such that the top and bottom rollers can engage with each other. By engaging with any of the bonding rollers 22, 32, and 42, the second bonding roller 52 can perform rolling pressure on the back surface of the electrode sheet 100, or more specifically, bonding pressure on the back surface of the uncoated portion 110.

[0087] Using a combination of top and bottom contact rollers on the top and bottom surfaces of electrode sheet 100 can be advantageous, especially when both the top and bottom surfaces of electrode sheet 100 are coated with an electrode mixture layer. However, the use of top and bottom contact rollers is not limited to such double-sided coated electrode sheets.

[0088] The second bonding roller 52 can be configured similarly to any one of the bonding rollers 22, 32, and 42 according to the above embodiments. The second bonding roller 52 may or may not have a preset angle relative to the platform 23 or the surface of the electrode sheet 100 to be bonded, as long as the opposing bonding roller (hereinafter referred to as the first roller) located on the upper surface of the electrode sheet 100 has a preset angle relative to the platform 23. Furthermore, the second bonding roller 52 may have a different preset angle than the first bonding rollers 22, 32, and 42 located above the platform 23.

[0089] The circumferential surface of the second bonding roller 52 that contacts the rear surface of the electrode sheet 100 may have an embossed pattern. The embossed patterns formed on the first bonding rollers 22, 32, 42 and the second bonding roller 52 may be the same or different. In the case of two different embossed patterns, the patterns transferred onto the top and bottom surfaces of the electrode sheet 100 will not overlap. For example, only one of the top and bottom surfaces of the uncoated portion 110 of the electrode sheet 100 may have a pattern to prevent or reduce damage.

[0090] According to one aspect of the invention, a method for rolling an electrode sheet first places the electrode sheet 100 on, for example, a platform 23, and then performs a pressing process (sheet pressing). Specifically, one or more uncoated portions 110 of the electrode sheet 100 are rolled by sheet pressing rollers 22, 32, 42, and 52. During the pressing process, the sheet pressing rollers 22, 32, 42, and 52 are applied to the electrode sheet 100 while forming a predetermined angle relative to the platform 23, such that the sheet pressing rollers 22, 32, 42, and 52 apply a smaller pressure on the side of the uncoated portion 110 closest to the coated portion 120 and in contact with the edge of the sheet pressing roller 22.

[0091] According to another aspect of the invention, an electrode sheet 100 manufactured by a method for rolling electrode sheets is provided. The electrode sheet may have a coated portion 120 located in the middle of its width and extending in its length direction, and uncoated portions 110 located on both sides of the coated portion 120. The electrode sheet 100 includes tabs formed from the uncoated portions 110, which have undergone a pressing process. Preferably, the tabs do not have a line pattern extending in their width direction and dividing one side of the tab with a certain height.

[0092] According to an embodiment of the invention, the contact patch may have a pattern formed on its surface, the pattern having a continuously varying depth depending on the distance from the coating portion 120 of the electrode patch 100.

[0093] According to an embodiment of the present invention, the depth of the pattern may be shallower in the portion closer to the coating portion 120 than in the portion farther away from the coating portion 120.

[0094] Although specific embodiments have been shown and described herein, those skilled in the art will understand that various alternative and / or equivalent embodiments exist. It should be understood that the exemplary embodiments are merely examples and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and specific embodiments will provide a convenient guide for those skilled in the art to implement at least one exemplary embodiment, and it should be understood that various changes can be made to the function and arrangement of the elements described in the exemplary embodiments without departing from the scope set forth in the appended claims. Generally, this application is intended to cover any modifications or variations of the specific embodiments discussed herein.

[0095] List of reference numerals

[0096] 10 and 20 are equipment used for rolling electrode sheets.

[0097] 11. Pressure rollers for the coating section

[0098] 12-piece pressing roller

[0099] 22-piece pressing roller

[0100] 23 Platform

[0101] 32-piece pressing roller

[0102] 41. Circular or chamfered parts

[0103] 42-piece pressing roller

[0104] 52 Second joint pressure roller

[0105] 100 electrode sheet

[0106] 110 Uncoated area

[0107] 120 Coating Part

Claims

1. An apparatus for rolling an electrode sheet, wherein the electrode sheet has a coated portion located in the middle of its width and extending in its length direction, and uncoated portions located on both sides of the coated portion, wherein the apparatus comprises: A platform for placing the electrode sheets; and A bonding roller, configured to roll over an uncoated portion of the electrode sheet to perform a pressing process. The joining pressure roller is configured to form a preset angle relative to the platform during the pressing process, such that the joining pressure roller applies less pressure on the side of the uncoated portion closer to the coated portion than on the other side farther from the coated portion.

2. The device according to claim 1, wherein the plate pressing roller has a truncated cone shape.

3. The apparatus of claim 1, wherein the sheet-attaching roller has a cylindrical shape and is configured to be applied to the electrode sheet during the pressing process while maintaining the preset angle relative to the platform.

4. The apparatus according to any one of the preceding claims, wherein the side of the sheet-attaching roller closest to the coated portion during the pressing process is rounded or chamfered.

5. The device according to any one of the preceding claims, wherein the surface of the electrode sheet contacting the electrode sheet during the pressing process has a raised or recessed pattern.

6. The device according to any one of the preceding claims further includes another bonding roller for bonding and pressing the uncoated portion of the electrode sheet from the opposite side of the bonding roller, wherein the bonding roller and the other bonding roller are configured to engage with each other, and the electrode sheet is disposed between the bonding roller and the other bonding roller.

7. The apparatus of claim 6, wherein the other sheet-joining pressure roller is configured to form a preset angle relative to the platform during the pressing process, such that the other sheet-joining pressure roller applies less pressure on the side of the uncoated portion closer to the coated portion than on the other side farther from the coated portion.

8. A method for rolling an electrode sheet, wherein the electrode sheet has a coated portion located in the middle of its width and extending in its length direction, and uncoated portions located on both sides of the coated portion, wherein the method comprises: Place the electrode sheet on the platform; and A pressing process is performed by rolling an uncoated portion of the electrode sheet using a bonding roller. During the pressing process, the bonding roller is applied to the electrode sheet while forming a preset angle relative to the platform, such that the bonding roller applies less pressure on the side of the uncoated portion closer to the coated portion than on the other side farther from the coated portion.

9. The method of claim 8, wherein the sheet-attaching pressure roller has a truncated cone shape, and during the pressing process, the sheet-attaching pressure roller is applied to the electrode sheet, and its axis of rotation is parallel to the platform.

10. The method of claim 9, wherein the contact roller has a cylindrical shape, and during the pressing process, the contact roller is applied to the electrode sheet, and its axis of rotation maintains the preset angle relative to the platform.

11. The method according to any one of the preceding claims, wherein during the pressing process, the sheet roller imparts an embossed pattern on the uncoated portion of the electrode sheet.

12. The method according to any one of the preceding claims further comprises: A pressing process is performed by rolling the uncoated portion of the electrode sheet using another pressing roller from the opposite side of the first pressing roller, wherein the first pressing roller and the other pressing roller are engaged with each other, and the electrode sheet is placed between the first pressing roller and the other pressing roller. During the pressing process, the other contact roller is applied to the electrode sheet while forming a preset angle relative to the platform, such that the other contact roller applies less pressure on the side of the uncoated portion closer to the coated portion than on the other side farther from the coated portion.

13. An electrode sheet manufactured by the method of claims 8 to 12, comprising: The coated portion that is located in the middle of its width and extends along its length. The uncoated portions located on both sides of the coated portion, and The tab formed from the uncoated portion, the tab having undergone the pressing process, The patch does not extend in its width direction and has a line pattern that divides one side of the patch from the other side with a certain height.

14. The electrode sheet of claim 13, wherein the electrode sheet comprises a pattern formed on its surface. The pattern includes a continuously varying depth depending on the distance from the coated portion of the electrode sheet.

15. The electrode sheet of claim 14, wherein the depth of the pattern is shallower in the portion closer to the coated portion than in the portion farther from the coated portion.

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