Apparatus and method for manufacturing secondary battery electrode plate and roller used therefor

Abstract

The present disclosure relates to an apparatus and a method for manufacturing a secondary battery electrode plate, and a roller used therein. The apparatus for manufacturing a secondary battery electrode plate includes: a coating unit configured to coat an electrode material slurry on a substrate to form an electrode plate; a rolling unit configured to roll the electrode plate; a slitting unit configured to slit the rolled electrode plate in a moving direction of the rolled electrode plate; and a transfer unit including a roller contacting with a corresponding electrode plate among the electrode plate, the rolled electrode plate, and the slit electrode plate to transfer the corresponding electrode plate. The roller has a first diameter portion having a first diameter, a second diameter portion having a smaller diameter than the first diameter portion, and an inclined portion extending between the first diameter portion and the second diameter portion.

Description

Technical Field

[0001] Aspects of embodiments of the present disclosure relate to an apparatus and method for manufacturing a secondary battery electrode plate and a roller used in the apparatus and method. Background Art

[0002] Unlike a primary battery that is not designed to be charged, a secondary battery is designed to be discharged and charged. Generally, a secondary battery includes an electrode assembly and a housing (e.g., a case or can) that houses the electrode assembly, and the electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. Depending on the type of stacking of the electrode plates and the separator, the electrode assembly can be classified into a wound electrode assembly or a stacked electrode assembly. The wound electrode assembly can be in the form of a jelly roll, and the stacked electrode assembly can be in the form of a stack.

[0003] The positive and negative electrode plates of the electrode assembly can be manufactured by coating a substrate with a slurry containing an electrode active material to form an electrode plate, roll-pressing the slurry-coated electrode plate, and then longitudinally (e.g., in the conveying direction of the electrode plate) slitting the roll-pressed electrode plate.

[0004] In the process of manufacturing a secondary battery, during a pressing (e.g., roll-pressing) process, due to the height (or thickness) difference between the non-coated portion and the coated portion of the electrode plate, the non-coated portion and the coated portion of the electrode plate may exhibit elongation differences, resulting in stress generation in the electrode plate. During a subsequent slitting process, when the electrode plate is slit, since its width decreases, the stress may be unevenly distributed, resulting in asymmetric deformation such as curvature or skew in the slit electrode plate.

[0005] This problem may occur not only in the non-coated portion and the coated portion of the slit electrode plate but also in the electrode plate in other processes. In addition, this problem may occur not only in the non-coated portion / coated portion but also in any electrode plate including various parts (or portions) having different thicknesses (such as a thin portion (hereinafter, a first thickness portion) and a thick portion (hereinafter, a second thickness portion)).

[0006] The above information disclosed in this background art section is used to enhance the understanding of the background of the present disclosure. Therefore, it may contain information that does not constitute related (or prior) art. Summary of the Invention

[0007] Embodiments of the present disclosure provide an improved roller (including both a drive roller and an idler roller) that conveys a slit electrode plate having a coated portion and an uncoated portion or an electrode plate manufactured in other processes having portions of different thicknesses. According to embodiments of the present disclosure, by making the diameter of the roller portion in contact with the first thickness portion or the uncoated portion of the electrode plate larger than the diameter of the roller portion in contact with the second thickness portion (which is thicker than the first thickness portion) or the coated portion of the electrode plate, and allowing a greater external force to act on the first thickness portion or the uncoated portion, thereby causing additional elongation of the first thickness portion or the uncoated portion, deformation of the electrode is alleviated or avoided.

[0008] According to an embodiment of the present disclosure, an apparatus for manufacturing a secondary battery electrode plate includes: a coating unit configured to coat an electrode material slurry on a substrate to form an electrode plate; a rolling unit configured to roll the electrode plate; a slitting unit configured to slit the rolled electrode plate in the conveying direction (moving direction) of the rolled electrode plate; and a conveying unit including a roller that contacts a corresponding one of the electrode plate, the rolled electrode plate, and the slit electrode plate to convey the corresponding electrode plate. The roller in contact with the electrode plate has a first diameter portion having a first diameter, a second diameter portion having a diameter smaller than the first diameter portion, and an inclined portion connecting the first diameter portion and the second diameter portion.

[0009] According to another embodiment of the present disclosure, a method of manufacturing a secondary battery electrode plate includes: coating an electrode material slurry on a substrate to form an electrode plate; rolling the electrode plate; slitting the rolled electrode plate in the conveying direction (moving direction) of the rolled electrode plate; and conveying the relevant one of the electrode plate, the rolled electrode plate, and the slit electrode plate by the roller, and the roller contacts the relevant electrode plate. The roller in contact with the electrode plate has a first diameter portion having a first diameter, a second diameter portion having a diameter smaller than the first diameter portion, and an inclined portion extending between the first diameter portion and the second diameter portion. The electrode plate conveyed by the roller has a first thickness portion in contact with the first diameter portion of the roller, a second thickness portion in contact with the second diameter portion of the roller and thicker than the first thickness portion, and a boundary portion between the first thickness portion and the second thickness portion in contact with the inclined portion of the roller.

[0010] In some embodiments, the electrode plate conveyed by the roller may have a first thickness portion in contact with the first diameter portion of the roller, a second thickness portion in contact with the second diameter portion of the roller and thicker than the first thickness portion, and a boundary portion between the first thickness portion and the second thickness portion in contact with the inclined portion of the roller. The electrode plate may be a slit electrode plate slit by the slitting unit, the first thickness portion may be an uncoated portion of the slit electrode plate, and the second thickness portion may be a coated portion of the slit electrode plate.

[0011] In some embodiments, a roller for manufacturing a secondary battery electrode plate is provided. The roller contacts the electrode plate to convey the electrode plate, and the roller has a first diameter portion having a first diameter, a second diameter portion having a diameter smaller than that of the first diameter portion, and an inclined portion extending between the first diameter portion and the second diameter portion.

[0012] According to an embodiment of the present disclosure, a driving roller or an idle roller for conveying an electrode plate has a large diameter portion and a small diameter portion to position and convey the electrode plate such that a first thickness portion or an uncoated portion of the electrode plate contacts the large diameter portion, and a second thickness portion or a coated portion of the electrode plate that is thicker than the first thickness portion contacts the small diameter portion. Accordingly, by mainly applying pressure to the first thickness portion or the uncoated portion (whose elongation amount is smaller (or less) compared to the coated portion) to increase the elongation amount and reduce the difference in elongation degree between the first thickness portion or the uncoated portion and the second thickness portion or the coated portion, deformation of the electrode plate, such as bending or skew, can be avoided or alleviated. In addition, the roller has an inclined portion between its large diameter portion and small diameter portion. Accordingly, by bringing a boundary portion between the first thickness portion or the uncoated portion and the second thickness portion or the coated portion into contact with the inclined portion, damage to the boundary portion between the first thickness portion or the uncoated portion and the second thickness portion or the coated portion can be reduced.

[0013] However, aspects and features of the present disclosure are not limited to those described above, and other aspects and features not mentioned herein will be clearly understood by those skilled in the art from the detailed description described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The following attached drawings illustrate embodiments of the present disclosure and are provided to further describe aspects and features of the present disclosure together with the detailed description of the present disclosure. Accordingly, the present disclosure should not be construed as being limited to the drawings, in which:

[0015] Figure 1 An electrode assembly of a secondary battery is schematically shown;

[0016] Figure 2 A pouch-type secondary battery is schematically shown;

[0017] Figure 3 is a cross-sectional view of a cylindrical secondary battery;

[0018] Figure 4 is a cross-sectional view showing an internal configuration of a prismatic secondary battery;

[0019] Figure 5 describes the manufacturing Figure 1 of the electrode plate of the electrode assembly shown in;

[0020] Figure 6 It is a schematic view showing a slitting unit and a conveying unit for conveying the slit electrode plates to a rewinder;

[0021] Figure 7 It is a view schematically showing a slit electrode plate where a coating layer and a non - coating layer coexist;

[0022] Figure 8 It is a perspective view showing a roller according to an embodiment of the present disclosure;

[0023] Figure 9 It schematically shows that the slit electrode plate passes through Figure 8 the state of being conveyed by the roller shown in;

[0024] Figure 10 It schematically shows the state where the slit electrode plate is conveyed by two rollers according to another embodiment of the present disclosure;

[0025] Figure 11 It schematically shows the state where the electrode plate with an insulating layer applied on the non - coating part is conveyed by a roller;

[0026] Figure 12 It shows Figure 8 the main dimensions of the shape of the roller shown in;

[0027] Figure 13 It is a view of a secondary battery module in which a secondary battery is arranged according to an embodiment of the present disclosure;

[0028] Figure 14 It includes Figure 13 a view of a secondary battery pack including the secondary battery module shown in; and

[0029] Figure 15 It is a conceptual view of a vehicle equipped with Figure 14 the secondary battery pack shown in; Detailed Embodiments

[0030] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The terms or words used in the present disclosure and the claims should be interpreted as having meanings and concepts consistent with the technical idea of the present disclosure based on the principle that the inventor can be his / her own lexicographer to appropriately define the terms so as to describe his / her invention in a suitable manner.

[0031] The embodiments described in this specification and the configurations shown in the drawings are only some embodiments of the present disclosure and do not represent all of the embodiments of the present disclosure. Therefore, it should be understood that there can be various equivalents and modifications capable of replacing or modifying one or more of the embodiments described herein at the time of filing this application.

[0032] It will be understood that if an element or layer is referred to as being "on", "linked to", "connected to", or "coupled to" another element or layer, it can be directly on, directly linked to, directly connected to, or directly coupled to the other element or layer, or there can also be one or more intervening elements or layers. When an element or layer is referred to as being "directly on", "directly linked on", "directly connected to", or "directly coupled to" another element or layer, there are no intervening elements or layers. For example, when a first element is described as being "coupled" or "connected" to a second element, the first element can be directly coupled or connected to the second element, or the first element can be indirectly coupled or connected to the second element via one or more intervening elements.

[0033] In the drawings, for clarity of illustration, the dimensions of various elements, layers, etc. may be exaggerated. Like reference numerals denote like elements. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Further, if embodiments of the present disclosure are described, the use of "may" pertains to "one or more embodiments of the present disclosure". Expressions such as "at least one of..." and "any one of..." when following a list of elements modify the entire list of elements and not individual elements of the list. When phrases such as "at least one of A, B, and C", "at least one of A, B, or C", "at least one selected from the group consisting of A, B, and C", or "at least one selected from among A, B, and C" are used to specify a list of elements A, B, and C, the phrase can refer to any and all suitable combinations or subsets of A, B, and C, such as A, B, C, A and B, A and C, B and C, or A and B and C. As used herein, the terms "use", "using...", and "being used" can be considered to be synonymous with the terms "utilize", "utilizing...", and "being utilized", respectively. As used herein, the terms "substantially", "about", and similar terms are used as approximating terms and not terms of degree, and are intended to account for the inherent variations in measured or calculated values that would be recognized by a person of ordinary skill in the art.

[0034] It will be understood that although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, the first element, component, region, layer, or section discussed below may be referred to as the second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0035] For ease of description, spatial relationship terms such as "beneath", "below", "under", "above", "on", etc. may be used herein to describe the relationship of one element or feature to another element or feature as shown in the figures. It will be understood that, in addition to the orientation depicted in the figures, the spatial relationship terms are also intended to encompass different orientations of the device during use or operation. For example, if the device in the figures is flipped over, an element described as "beneath" or "under" another element or feature will be oriented "above" or "over" the other element or feature. Thus, the term "beneath" can encompass both an upper and a lower orientation. The device may be oriented in other ways (rotated 90 degrees or at other orientations), and the spatial relationship descriptors used herein should be interpreted accordingly.

[0036] The terms used herein are for the purpose of describing embodiments of the present disclosure and are not intended to limit the present disclosure. As used herein, the singular form "a" is also intended to include the plural form unless the context clearly indicates otherwise. It will be further understood that the terms "comprises", "comprising", "includes", and / or "including", if used in this specification, specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0037] In addition, any numerical range disclosed and / or recited herein is intended to include all sub-ranges of the same numerical precision that fall within the recited range. For example, the range "1.0 to 10.0" is intended to include all sub-ranges between the recited minimum value of 1.0 and the recited maximum value of 10.0 (and including the recited minimum value of 1.0 and the recited maximum value of 10.0), that is, all sub-ranges having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4 to 7.6. Any maximum numerical limitation recited herein is intended to include all lower numerical limitations subsumed therein, and any minimum numerical limitation recited in this specification is intended to include all higher numerical limitations subsumed therein. Accordingly, the applicant reserves the right to amend this specification (including the claims) to expressly recite any sub-ranges that fall within the ranges expressly recited herein. All such ranges are intended to be inherently described in this specification such that amending to expressly recite any such sub-ranges will comply with the requirements of the patent laws.

[0038] Two compared elements, features, etc. being referred to as "the same" can mean that they are "substantially the same". Thus, the phrase "substantially the same" can include comparisons having a deviation that is considered low in the art (e.g., a deviation of 5% or less). Additionally, if a certain parameter is said to be uniform in a given region, this can mean that it is uniform in terms of the average value.

[0039] Throughout the specification, unless stated otherwise, each element can be singular or provided as plural.

[0040] Positioning any element "above (or below)" or "on (or under)" an element can mean that the any element can contact the upper (or lower) surface of the element, and another element can be interposed between the element and the any element located on (or under) the element.

[0041] Additionally, it will be understood that if a component is referred to as being "linked", "coupled", or "connected" to another component, the components can be "coupled", "linked", or "connected" directly to each other, or another component can be "interposed" between the components.

[0042] Throughout the specification, if it is stated "A and / or B", it means A, B, or A and B, unless stated otherwise. That is, "and / or" includes any or all combinations of the recited items. When it is stated "C to D", it means C or more and D or less, unless otherwise specified.

[0043] The terms used herein are for the purpose of describing embodiments of the present disclosure and are not intended to limit the present disclosure.

[0044] Figure 1Shows an electrode assembly of a secondary battery.

[0045] The electrode assembly 10 may be formed by winding or stacking a stack of a first electrode plate 11, a separator 12, and a second electrode plate 13, and the first electrode plate 11, the separator 12, and the second electrode plate 13 are formed as thin plates or films. When the electrode assembly 10 is a wound stack, the winding axis may be parallel to the longitudinal direction of the case 51 (see, for example Figure 4 ). In other embodiments, the electrode assembly 10 may be a stacked type rather than a wound type, but the shape of the electrode assembly 10 is not limited in the present disclosure. Additionally, the electrode assembly 10 may be a Z-stack electrode assembly in which a positive electrode plate and a negative electrode plate are inserted on both sides of the separator and then bent into a Z-stack. Additionally, one or more electrode assemblies may be stacked such that the long sides of the electrode assemblies are adjacent to each other and accommodated in the case, and the number of electrode assemblies in the case is not limited in the present disclosure. The first electrode plate 11 of the electrode assembly 10 may serve as a negative electrode, and the second electrode plate 13 may serve as a positive electrode. Of course, the reverse is also possible.

[0046] The first electrode plate 11 may be formed by applying a first electrode active material (such as graphite or carbon) to a first electrode current collector formed of a metal foil (such as copper, copper alloy, nickel, or nickel alloy). The first electrode plate 11 may include a first electrode tab 14 (e.g., a first non-coated portion), which is an area where the first electrode active material is not applied. The first electrode tab 14 may be connected to an external first terminal. In some embodiments, when manufacturing the first electrode plate 11, the first electrode tab 14 may be formed by pre-cutting to protrude to one side of the electrode assembly 10, or the first electrode tab 14 may protrude to one side of the electrode assembly 10 more (e.g., farther or beyond the separator 12) than the separator 12 without separate cutting.

[0047] The second electrode plate 13 may be formed by applying a second electrode active material (such as a transition metal oxide) on a second electrode current collector formed of a metal foil (such as aluminum or aluminum alloy). The second electrode plate 13 may include a second electrode tab 15 (e.g., a second non-coated portion), which is an area where the second electrode active material is not applied. The second electrode tab 15 may be connected to an external second terminal. In some embodiments, when manufacturing the second electrode plate 13, the second electrode tab 15 may be formed by pre-cutting to protrude to one side of the electrode assembly 10, or the second electrode tab 15 may protrude to one side of the electrode assembly 10 more (e.g., farther or beyond the separator 12) than the separator 12 without separate cutting.

[0048] In some embodiments, the first electrode tab 14 and the second electrode tab 15 may be located on opposite sides of the electrode assembly 10 (see, for example, Figure 3 and Figure 4 ). In other embodiments, the first electrode tab 14 and the second electrode tab 15 may be located on one side in the same direction of the electrode assembly 10 (see, for example, Figure 1 and Figure 2 ).

[0049] The separator 12 prevents short - circuit between the first electrode plate 11 and the second electrode plate 13, while allowing lithium ions to move between them. The separator 12 may be made of, for example, a polyethylene film, a polypropylene film, a polyethylene - polypropylene film, etc.

[0050] In some embodiments, the electrode assembly 10 may be accommodated in a housing together with an electrolyte.

[0051] In a pouch - type secondary battery, the electrode assembly 10 may be accommodated in a pouch made of a flexible material (see, for example, Figure 2 ). In a cylindrical or prismatic secondary battery, the electrode assembly 10 may be accommodated in a cylindrical or prismatic metal housing (see, for example, Figure 3 and Figure 4 ).

[0052] Figure 2 A pouch - type secondary battery is schematically shown.

[0053] The pouch - type secondary battery includes an electrode assembly 10 and a pouch 20 that houses the electrode assembly 10.

[0054] The electrode assembly 10 is the same as that shown in Figure 1 . The first electrode tab 14 and the second electrode tab 15 of the electrode assembly 10 may be electrically connected to the corresponding external first terminal lead 16 and second terminal lead 17 by welding. Each of the first terminal lead 16 and the second terminal lead 17 may be attached with a tab film 18 (for example, covered by the tab film 18) for insulation from the pouch 20.

[0055] The pouch 20 may be sealed while housing the electrode assembly 10 by having a sealing portion 21 at its edge (the sealing portions 21 contact each other), and the tab film 18 is interposed between the sealing portions 21. Each of the sealing portions 21 of the pouch 20 may be made of a hot - melt material that generally has weak adhesion to metal. Thus, the first electrode tab 14 and the second electrode tab 15 can be fused to the pouch 20 by interposing the tab film 18 between the sealing portions 21.

[0056] Figure 3 A cylindrical secondary battery is shown. Referring to Figure 3, the secondary battery may include an electrode assembly 10, a case 31 that houses the electrode assembly 10 and an electrolyte, a cap assembly 32 coupled to an opening in the case 31 to seal the case 31, and an insulating plate 33 disposed inside the case 31 between the electrode assembly 10 and the cap assembly 32.

[0057] The case 31 houses the electrode assembly 10 and the electrolyte and forms an exterior appearance of the secondary battery together with the cap assembly 32. The case 31 may have a substantially cylindrical body portion and a bottom portion connected to one side (e.g., one end) of the body portion. An inwardly deformed beading portion 34 (e.g., a bead) may be formed in the body portion, and an inwardly curved crimping portion 35 (e.g., a crimp) may be formed at an open end of the body portion.

[0058] The beading portion 34 may reduce or prevent movement of the electrode assembly 10 inside the case 31 and may assist in the positioning of the gasket 36 and the cap assembly 32. The crimping portion 35 may firmly fix the cap assembly 32 by pressing an edge of the case 31 against the gasket 36. For example, the case 31 may be formed of nickel-plated iron.

[0059] The cap assembly 32 may be fixed to the inside of the crimping portion 35 through the gasket 36 to seal the case 31.

[0060] A first lead tab 37 pulled out (e.g., extending from) the electrode assembly 10 may be connected to the cap assembly 32, and a second lead tab 38 pulled out (e.g., extending from) the electrode assembly 10 may be electrically connected to the bottom of the case 31.

[0061] Figure 4 An internal structure of a prismatic secondary battery is shown.

[0062] As Figure 4 shown, the prismatic secondary battery may include an electrode assembly 40, a first current collector 41, a first terminal 62, a second current collector 42, a second terminal 63, a case 51, and a cap assembly 60.

[0063] The electrode assembly 40 may be formed by winding or stacking a stack of a first electrode plate, a separator, and a second electrode plate, and the first electrode plate, the separator, and the second electrode plate are formed as thin plates or films. If the electrode assembly 40 is a wound stack, the winding axis may be parallel to the longitudinal direction of the housing 51. In other embodiments, the electrode assembly 40 may be a stacked type rather than a wound type, but the shape of the electrode assembly 40 is not limited in the present disclosure. Additionally, the electrode assembly 40 may be a Z-stacked electrode assembly, where a positive electrode plate and a negative electrode plate are inserted on both sides of the separator and then bent into a Z-stack. Additionally, one or more electrode assemblies may be stacked such that the long sides of the electrode assemblies are adjacent to each other and housed in the housing, and the number of electrode assemblies in the housing is not limited in the present disclosure. The first electrode plate of the electrode assembly may be used as the negative electrode, and the second electrode plate may be used as the positive electrode. Of course, the reverse is also possible.

[0064] In the electrode assembly 40, a first current collector 41 and a second current collector 42 may be respectively welded and connected to a first electrode tab 43 extending from the first electrode plate and a second electrode tab 44 extending from the second electrode plate. As described above, in some embodiments where the first electrode tab 43 and the second electrode tab 44 are located at the top of the electrode assembly 40, the first current collector and the second current collector will be located at the top of the electrode assembly 40.

[0065] As Figure 4 shown, the first current collector 41 and the second current collector 42 are respectively connected to a first terminal 62 and a second terminal 63 through a connection member 67. In some embodiments, the connection member 67 may each have a threaded outer peripheral surface and may be fastened to the first terminal 62 and the second terminal 63 by a threaded connection. However, the present disclosure is not limited thereto. For example, the connection member 67 may also be joined to the first terminal 62 and the second terminal 63 by riveting or welding.

[0066] Figure 5 is a schematic diagram of the process of manufacturing Figure 1 the electrode plate (e.g., the first electrode plate 11 or the second electrode plate 13) of the electrode assembly 10 shown in

[0067] The supply roller 110 is a roller around which a substrate P1 for the electrode plate is wound. When the apparatus for manufacturing an electrode plate according to an embodiment of the present disclosure is used to manufacture a positive electrode plate, the substrate P1 may be, for example, a metal foil containing aluminum (Al). When the apparatus for manufacturing an electrode plate according to an embodiment of the present disclosure is used to manufacture a negative electrode plate, the substrate P1 may be a metal foil containing copper (Cu) or nickel (Ni).

[0068] The transfer roller 150 may be an idle roller that guides the substrate P1 after the substrate P1 is unwound from the supply roller 110, or a driving roller that applies a pulling force to allow the substrate P1 to be unwound from the supply roller 110.Figure 5 An embodiment including a total of four transfer rollers 150 is shown as an example, but the number and positions of the transfer rollers may vary.

[0069] The coating unit 120 forms a coating by coating the substrate P1 with a pre-prepared electrode material slurry. The slurry contains an active material. When the device is used to manufacture a positive electrode plate, the slurry can be prepared with an active material containing, for example, a transition metal oxide, a binder, a volatile solvent, etc. When the device is used to manufacture a negative electrode plate, the slurry can be prepared with an active material containing a transition metal oxide, a binder, a solvent, etc. In addition, the two surfaces (e.g., the upper surface and the lower surface) of the substrate P1 can be coated in parallel (or simultaneously) by adding a second coating unit 120' (which may have the same configuration as the coating unit 120) to the lower surface of the substrate P1.

[0070] The rolling unit (e.g., the rolling pressing unit) 130 presses the electrode plate P2 coated with the slurry (mixture) by the coating unit 120 using pressing rollers to produce a secondary battery with high capacity and high density.

[0071] The winding roller 140 is a roller that winds and accommodates the electrode plate P3 coated and rolled by the coating unit 120 and the rolling unit 130.

[0072] A drying unit can be added between the coating unit 120 and the winding roller 140 to dry or cure the electrode plate P2 coated with the slurry. The drying unit can include a heating device. In addition, the drying unit can be physically separated from the rolling unit 130 or otherwise functionally integrated into the rolling unit 130. For example, when the rolling unit 130 is configured in the form of a roller, the roller can be equipped with a heating device to heat and roll the coating in parallel (or simultaneously), thereby allowing the rolling unit 130 to be configured to also function as a drying unit.

[0073] Figure 6 is a schematic diagram showing the slitting unit 160 and the transfer units 170a and 170b. The slitting unit 160 longitudinally (e.g., in the moving direction of the electrode plate) slits the electrode plate P3 rolled by the rolling unit 130 and wound around the winding roller 140 (as Figure 5 shown), and the transfer units 170a and 170b are used to transfer the slit electrode plates 80a and 80b to the corresponding rewinding machines 180a and 180b.

[0074] Two electrode plates 80a and 80b that are slit (e.g., cut in the longitudinal direction of the electrode plate, i.e., in the moving direction of the electrode plate) and separated by the slitting unit 160 can be respectively conveyed to the rewinding machines 180a and 180b through a plurality of rollers 171a, 172a, 173a included in the conveying units 170a and 170b and 171b, 172b, 173b and rewound on the rewinding machines 180a and 180b.

[0075] The slitting unit 160 slits the electrode plate P3 coated and roll-pressed in the process described with reference to Figure 5 along a line of a cutting plane parallel to the conveying direction to separate the electrode plate P3 into individual rows. When passing through this slitting process, the slit electrode plate 80 in the form of a strip can be obtained, in which the coated portion 90 and the non-coated portion 95 coexist (e.g., having both the coated portion 90 and the non-coated portion 95). The coated portion 90 has a second thickness and a coating is formed thereon. The non-coated portion 95 has a first thickness smaller than the second thickness and no coating is formed thereon, as Figure 7 shown.

[0076] The slitting unit 160, the conveying units 170a and 170b, and the rewinding machines 180a and 180b can be arranged in a continuous line behind (or after) the roll-pressing unit 130 shown in Figure 5 or can be organized into separate production lines, as Figure 6 shown. In the latter embodiment, the electrode plate P3 obtained by roll-pressing the electrode plate P2 through the production line shown in Figure 5 can be wound on the winding roller 140 and conveyed to a separately organized slitting line, as Figure 6 shown. Then, in the slitting line, the electrode plate P3 can be unwound from the winding roller 140 and slit by the slitting unit 160 in the conveying direction of the electrode plate P3.

[0077] Since the portion roll-pressed by the roll-pressing unit 130 is mainly the thick-coated portion, there may be a difference in elongation between the coated portion and the non-coated portion because the elongation amount generated by roll-pressing is larger in the coated portion than in the non-coated portion. In this case, the electrode plate does not deform because the electrode plate has a relatively large width before slitting and the stress generated due to the difference in elongation is dispersed on (or through) the electrode plate. However, since the slit electrode plate 80 obtained by the slitting process has a small width and the stress generated due to the difference in elongation between the coated portion 90 and the non-coated portion 95 is unevenly (or non-uniformly) dispersed on (or through) the electrode plate (as Figure 7As shown, deformation of the electrode plate, such as bending or skewing, may occur in the electrode plate 80. If the electrode plate 80 is continuously deformed, the electrode plate 80 may break during subsequent assembly processes, such as winding or slitting.

[0078] To reduce or minimize electrode deformation, a method of increasing ductility (weakening tensile strength) by applying induction heat annealing (IHA) may be applied to the non-coated portion 95 to increase the elongation of the non-coated portion during the pressing process. However, as the degree of compression in the rolling process increases with the trend of producing electrodes with high energy density and the difference in elongation between the coated portion 90 and the non-coated portion 95 increases, an additional (or alternative) method for reducing electrode deformation is needed.

[0079] Figure 8 FIG. shows one of the plurality of rollers 171 included in the transfer units 170a and 170b according to an embodiment of the present disclosure. The roller 171 may be a driving roller or an idle roller. According to an embodiment of the present disclosure, the roller 171 may include two portions having different diameters, for example, a large-diameter portion 191 and a small-diameter portion 192, wherein an inclined portion 193 extends between the large-diameter portion 191 and the small-diameter portion 192. Hereinafter, the large-diameter portion 191 will be referred to as the first diameter portion, and the small-diameter portion 192 will be referred to as the second diameter portion. The second diameter portion 192 has a diameter smaller than that of the first diameter portion 191.

[0080] Figure 9 FIG. schematically shows a state in which the slit electrode plate 80 is transferred by the roller 171. The following embodiments will be described in the context of reducing or preventing deformation (such as bending or skewing) of the slit electrode plate 80 including the coated portion 90 and the non-coated portion 95, but the aspects and features of the present disclosure are not limited thereto. For example, the electrode plate may refer to an electrode plate manufactured by other processes, such as coating, pressing, and drying, as well as the slit electrode plate 80, and may also include an electrode plate having portions with different thicknesses and an electrode plate including a non-coated portion and a coated portion.

[0081] When the electrode plate 80 is transferred by the roller 171, the electrode plate 80 may be positioned such that the non-coated portion 95 contacts the first diameter portion 191, the coated portion 90 contacts the second diameter portion 192, and the boundary portion 91 between the non-coated portion 95 and the coated portion 90 contacts the inclined portion 193. Since the non-coated portion 95 is transferred in contact with the first diameter portion 191, pressure is mainly applied to the non-coated portion 95 (as Figure 7As shown, the elongation of the non-coated portion 95 is smaller than that of the coated portion 90), thereby generating additional elongation. Therefore, the difference in elongation between the non-coated portion 95 and the coated portion 90 can be reduced, thereby reducing or avoiding deformation (such as bending or skewing) of the electrode plate 80.

[0082] The boundary portion 91 between the coated portion 90 and the non-coated portion 95 is located on the inclined portion 193 (the inclined portion 193 has a diameter that gradually decreases between the first diameter portion 191 and the second diameter portion 192 of the roller 171), which can relieve the pressure applied to the boundary portion 91 between the coated portion 90 and the non-coated portion 95 and the bending at the boundary portion 91 between the coated portion 90 and the non-coated portion 95. Therefore, damage to the electrode plate can be prevented. Since the inclined portion 193 has a tapered diameter, the boundary portion 91 between the coated portion 90 and the non-coated portion 95 does not have to coincide (or precisely coincide) with the starting point of the inclined portion 193.

[0083] In some embodiments, the roller 171 can be manufactured such that the frictional force between the non-coated portion 95 of the electrode plate 80 and the first diameter portion 191 of the roller 171 is different from the frictional force between the coated portion 90 and the second diameter portion 192. For example, the first diameter portion 191 and the second diameter portion 192 can be formed (or machined) such that the surface frictional force of the second diameter portion 192 in contact with the coated portion 90 is greater than the surface frictional force of the first diameter portion 191 in contact with the non-coated portion 95. When the electrode plate 80 is conveyed through the roller 171, this difference in frictional force can prevent the electrode plate 80 from slipping due to the difference in pressure applied to the coated portion 90 and the non-coated portion 95 by the first diameter portion 191 and the second diameter portion 192 of different diameters.

[0084] According to an embodiment, in order to provide a frictional force between the first diameter portion 191 and the non-coated portion 95 that is different from the frictional force between the second diameter portion 192 and the coated portion 90, the surface roughness of the first diameter portion 191 can be different from the surface roughness of the second diameter portion 192. For example, the surface of the second diameter portion 192 can be machined to be rougher than the surface of the first diameter portion 191.

[0085] According to another embodiment, in order to provide a frictional force between the first diameter portion 191 and the non-coated portion 95 that is different from the frictional force between the second diameter portion 192 and the coated portion 90, the first diameter portion 191 and the second diameter portion 192 can be made of different materials. For example, the second diameter portion 192 can be made of a material with higher frictional force, and the first diameter portion 191 can be made of a material with relatively low frictional force.

[0086] According to another embodiment, in order to provide a frictional force between the first diameter portion 191 and the uncoated portion 95 that is different from the frictional force between the second diameter portion 192 and the coated portion 90, coatings with different frictional forces can be formed on the first diameter portion 191 and the second diameter portion 192. For example, a coating with a higher frictional force can be formed on the second diameter portion 192, and a coating with a relatively low frictional force can be formed on the first diameter portion 191.

[0087] Figure 10 The state in which the electrode plate 80 is conveyed by two rollers 172 and 173 (or between the two rollers 172 and 173) is schematically shown. In order to avoid problems such as insufficient elongation of the uncoated portion 95 or the electrode plate 80 being bent only to one side when the electrode plate 80 is conveyed by one roller 171 in the embodiment shown in Figure 9 , a plurality of rollers 172 and 173 can be used, each roller having the same shape as that shown in Figure 8 .

[0088] When two or more rollers are used as shown in Figure 10 , different surfaces (e.g., opposite surfaces) of the electrode plate 80 can be in contact with the corresponding rollers. For example, the electrode plate 80 can be conveyed in such a way that its first surface is in contact with the first roller 172 and its second surface is in contact with the second roller 173. Such an arrangement can prevent or avoid the electrode plate 80 from being bent only to one side. In addition, since the electrode plate 80 is conveyed by two rollers 172 and 173, the elongation of the uncoated portion 95 can be doubled.

[0089] In the process of coating an electrode plate (see, for example, Figure 5 ), sometimes an insulating portion (or insulating layer) can be formed by applying an insulating layer to some regions of the uncoated portion. The insulating portion can be formed longitudinally and have a width (e.g., a predetermined width) at the boundary between the uncoated portion and the coated portion. The insulating portion can have a third thickness that is equal to or different from the thicknesses of the uncoated portion and the coated portion.

[0090] Figure 11 The state in which the electrode plate 82 having the insulating portion 97 formed on the uncoated portion 95 according to an embodiment of the present disclosure is conveyed by the roller 171 is shown. The insulating portion 97 is formed with a width on (or above) the uncoated portion 95 of the electrode plate 82. The boundary portion 91 between the coated portion 90 and the insulating portion 97 and the boundary portion 92 between the uncoated portion 95 and the insulating portion 97 are shown.

[0091] In the electrode plate 82, the insulating portion 97 may be located (e.g., disposed) on the inclined portion 193 of the roller 171. The boundary portion 91 between the coating portion 90 and the insulating portion 97 and the boundary portion 92 between the non - coating portion 95 and the insulating portion 97 may be located at least at the starting point and the ending point of the inclined portion 193.

[0092] Figure 12 The dimensions defining the shape of each of the rollers 171, 172, or 173 according to an embodiment of the present disclosure are shown. In Figure 12 wherein, r1 represents the radius of the second diameter portion 192, r2 represents the radius of the first diameter portion 191, L1 represents the length of the inclined portion 193, and θ represents the inclination angle of the inclined portion 193 (e.g., the angle with respect to the longitudinal outer surface of the first diameter portion 191 or the second diameter portion 192).

[0093] The roller 171 can be designed with the main dimensions defining its shape considering various factors. The factors to be considered may include whether the coating of the electrode plate is a single - side coating or a double - side coating. Additionally, as described above, the insulating portion 97 that can be added to a part of the width of the non - coating portion 95 can be one of the factors to be considered when designing the roller 171.

[0094] Table 1 below shows the experimental data obtained by the inventor to obtain the basis for designing the shape of the roller 171. The improvement rate of the bending or skew of the electrode plate 80 is calculated by changing the presence or absence of the insulating portion 97, the angle of the inclined portion 193, and the length of the inclined portion 193. The improvement rate m of the bending or skew can be calculated using the following formula. In the following formula, m1 is the bending or skew value of the existing electrode plate, and m2 is the bending or skew value of the electrode plate when applying the shape of the roller according to the embodiment of the present disclosure:

[0095]

[0096] [Table 1]

[0097]

[0098]

[0099] In the results of the experiment, in the case of the electrode plate 80 without the insulating portion 97, when L1 is 3 mm and θ is 5°, the improvement rate of bending is 40.0%, and the improvement rate of skew is 30.9%. When θ is 1°, the bending and skew are aggravated.

[0100] In the case of the electrode plate 82 having the insulating portion 97, when L1 is 1.5 mm, as θ increases, the improvement rates of bending and skew generally increase. However, when θ is 1°, the bending is aggravated and only the skew is improved, and when θ is 25° (that is, when the difference between the first diameter portion 191 and the second diameter portion 192 is relatively large), the electrode plate 82 breaks during conveyance. After the breakage occurs, L1 is changed to 1 mm. Therefore, when θ is 20°, the improvement rates of bending and skew are 93.3% and 93.1% respectively, and when θ is 10°, the improvement rates of bending and skew are 94.3% and 64.9% respectively.

[0101] Based on this experimental data, the shapes of each of the rollers 171, 172, or 173 can be designed according to the embodiments of the present disclosure as follows.

[0102] 1) The range of the angle θ formed by the inclined portion 193 is in the range of about 5° ≤ θ ≤ about 20°.

[0103] In such an embodiment, the narrower the width of the electrode plate, the larger the inclination angle can be applied to reduce the damage to the electrode plate. In addition, if an angle smaller than the above range is used, the effect of improving bending and skew may be reduced due to the decrease in the elongation amount through the roller. On the other hand, if a higher angle is used, the damage to the non-coated portion may be aggravated, resulting in severe waviness or breakage during the conveyance of the electrode plate.

[0104] 2) The length L1 of the inclined portion 193 is in the range of about 1 mm ≤ L1 ≤ about 3 mm.

[0105] 3) The difference between the radius r2 of the first diameter portion 191 and the radius r1 of the second diameter portion 192 is about 100 μm ≤ (r2 - r1) ≤ about 350 μm. If the range of this radius difference is subdivided according to the single-sided coating and double-sided coating of the electrode plate, the roller for conveying the double-sided coated electrode plate should exhibit about 150 μm ≤ (r2 - r1) ≤ about 350 μm, and the roller for conveying the single-sided coated electrode plate should exhibit about 100 μm ≤ (r2 - r1) ≤ about 300 μm. Since the double-sided coated electrode plate is thicker than the single-sided coated electrode plate, r2 - r1 is larger in the former embodiment.

[0106] Hereinafter, the materials that can be used for the secondary battery according to the present disclosure will be described.

[0107] As the positive electrode active material, a compound capable of reversibly inserting / extracting lithium (for example, a lithiated insertion compound) can be used. For example, at least one of composite oxides of lithium and metals selected from cobalt, manganese, nickel, and combinations thereof can be used.

[0108] The composite oxide can be a lithium transition metal composite oxide, and examples thereof can include lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, cobalt-free nickel-manganese-based oxides, or combinations thereof.

[0109] As an example, a compound represented by any of the following chemical formulas can be used: Li a A 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Mn 2-b X b O 4-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 < α < 2); Li a Ni 1-b- c Mn b X c O 2-α D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 < α < 2); Li a Ni b Co c L 1 d G e O2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 0.1); Li a NiG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a CoG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn 1-b G b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn2G bO4 (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn 1-g G g PO4 (0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5); Li (3-f) Fe2(PO4)3 (0 ≤ f ≤ 2); or Li a FePO4 (0.90 ≤ a ≤ 1.8).

[0110] In the above chemical formulas: A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; L 1 is Mn, Al, or a combination thereof.

[0111] The positive electrode of the lithium secondary battery may include a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer may include a positive electrode active material, and may also include a binder and / or a conductive material.

[0112] The content of the positive electrode active material ranges from about 90 wt% to about 99.5 wt% based on about 100 wt% of the positive electrode active material layer, and the contents of the binder and the conductive material range from about 0.5 wt% to about 5 wt% respectively based on about 100 wt% of the positive electrode active material layer.

[0113] The current collector may be aluminum (Al), but is not limited thereto.

[0114] The negative electrode active material may include a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and undoping lithium, or a transition metal oxide.

[0115] The material capable of reversibly intercalating / deintercalating lithium ions may be a carbon-based negative electrode active material, and the carbon-based negative electrode active material may include, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of crystalline carbon may include graphite, such as natural graphite or artificial graphite, and examples of amorphous carbon may include soft carbon, hard carbon, pitch carbide, mesophase pitch carbide, sintered coke, etc.

[0116] The Si-based negative electrode active material or the Sn-based negative electrode active material may be used as the material capable of doping and undoping lithium. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiO x (0 < x < 2), a Si-based alloy, or a combination thereof.

[0117] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one or more embodiments, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles.

[0118] The silicon-carbon composite may also include crystalline carbon. For example, the silicon-carbon composite may include a core containing crystalline carbon and silicon particles and an amorphous carbon coating on the surface of the core.

[0119] The negative electrode of the lithium secondary battery may include a current collector and a negative electrode active material layer on the current collector. The negative electrode active material layer may include a negative electrode active material and may also include a binder and / or a conductive material.

[0120] For example, the negative electrode active material layer may include from about 90 wt% to about 99 wt% of the negative electrode active material, from about 0.5 wt% to about 5 wt% of the binder, and from about 0 wt% to about 5 wt% of the conductive material.

[0121] A non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof may be used as the binder. If an aqueous binder is used as the negative electrode binder, a cellulose-based compound capable of imparting viscosity may also be included.

[0122] As the negative electrode current collector, one selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a conductive metal-coated polymer substrate, and combinations thereof may be used.

[0123] The electrolyte of the lithium secondary battery may include a non-aqueous organic solvent and a lithium salt.

[0124] The non-aqueous organic solvent acts as a medium through which ions participating in the electrochemical reaction of the battery can move.

[0125] The non-aqueous organic solvent may be a carbonate-based solvent, an ester-based solvent, an ether-based solvent, a ketone-based solvent, an alcohol-based solvent, an aprotic solvent, and may be used alone or in combination of two or more.

[0126] If a carbonate-based solvent is used, a mixture of cyclic carbonate and linear carbonate may be used.

[0127] Depending on the type of the lithium secondary battery, a separator may be present (e.g., disposed) between the first electrode plate (e.g., the negative electrode) and the second electrode plate (e.g., the positive electrode). As the separator, polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof may be used.

[0128] The separator may include a porous substrate and a coating on one or both surfaces of the porous substrate, the coating including an organic material, an inorganic material, or a combination thereof.

[0129] The organic material may include a polyvinylidene fluoride-based heavy antibody or a (meth)acrylic polymer.

[0130] The inorganic material may include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof, but is not limited thereto.

[0131] The organic material and the inorganic material may be mixed in a single coating or may be in the form of a coating containing an organic material and a coating containing an inorganic material laminated on top of each other.

[0132] Figure 13 is a view of a secondary battery module in which a prismatic secondary battery is arranged according to an embodiment of the present disclosure. As the capacity of secondary batteries for driving electric vehicles and the like increases, a secondary battery module can be manufactured by arranging a plurality of secondary battery cells horizontally and / or vertically and connecting them together. The plurality of secondary battery cells may be arranged in a space defined by a pair of facing / opposite end plates 68a and 68b and a pair of facing / opposite side plates 69a and 69b. The secondary battery cells may be provided and configured in both arrangement (e.g., orientation) and quantity to provide the required voltage and current specifications.

[0133] Figure 14 is a view schematically showing the configuration of a battery pack 70 according to an embodiment of the present disclosure. Referring to Figure 14 , the battery pack 70 may include components electrically connected to each battery and a pack housing that houses the components. In the drawings, some components, including bus bars, a cooling unit, external terminals for electrically connecting the batteries, etc., are omitted for ease of illustration.

[0134] The battery pack 70 may be installed on (or in) a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may be a four-wheeler or a two-wheeler, but is not limited thereto. Figure 15 shows a vehicle V according to an embodiment of the present disclosure, which includes the battery pack 70 shown in Figure 14 on its lower body. The vehicle V may operate by receiving power from the battery pack 70 (e.g., may be powered by receiving power from the battery pack 70).

[0135] Although the present disclosure has been described above with respect to embodiments of the present disclosure, the present disclosure is not limited thereto. Those skilled in the art can make various modifications and variations within the spirit of the present disclosure and the scope of equivalents of the appended claims (including equivalents thereof).

Claims

1. An apparatus for manufacturing an electrode plate of a secondary battery, the apparatus comprising: a coating unit configured to coat an electrode material paste on a substrate to form an electrode plate; a rolling unit configured to roll the electrode plate; a slitting unit configured to slit the rolled electrode plate in a moving direction of the rolled electrode plate; and a conveying unit including rollers that contact respective ones of the electrode plate, the rolled electrode plate, and the slit electrode plate to convey the respective electrode plate, wherein the roller has a first diameter portion having a first diameter, a second diameter portion having a diameter smaller than the first diameter portion, and an inclined portion extending between the first diameter portion and the second diameter portion.

2. The apparatus according to claim 1, wherein the electrode plate conveyed by the roller has a first thickness portion and a second thickness portion thicker than the first thickness portion, and wherein the electrode plate is configured such that the first thickness portion contacts the first diameter portion of the roller, the second thickness portion contacts the second diameter portion of the roller, and a boundary portion between the first thickness portion and the second thickness portion contacts the inclined portion.

3. The apparatus according to claim 2, wherein the electrode plate conveyed by the roller is the slit electrode plate slit by the slitting unit, wherein the first thickness portion is an uncoated portion of the electrode plate, and wherein the second thickness portion is a coated portion of the electrode plate.

4. The apparatus according to claim 1, wherein the electrode plate conveyed by the roller has a first thickness portion, a second thickness portion thicker than the first thickness portion, and a third thickness portion between the first thickness portion and the second thickness portion, and wherein the electrode plate is configured such that the first thickness portion contacts the first diameter portion of the roller, the second thickness portion contacts the second diameter portion of the roller, and the third thickness portion contacts the inclined portion of the roller.

5. The apparatus according to claim 4, wherein the electrode plate conveyed by the roller is the slit electrode plate slit by the slitting unit, wherein the first thickness portion is an uncoated portion of the electrode plate, wherein the second thickness portion is a coated portion of the electrode plate, and wherein the third thickness portion is an insulating portion of the electrode plate.

6. The apparatus according to claim 1, wherein the inclined portion of the roller has an inclination angle in the range of 5° to 20°.

7. The apparatus according to claim 1, wherein the inclined portion of the roller has a length in the range of 1 mm to 3 mm.

8. The apparatus according to claim 1, wherein a difference between radii of the first diameter portion and the second diameter portion of the roller is in the range of 100 μm to 350 μm.

9. The apparatus according to claim 1, wherein the first diameter portion and the second diameter portion of the roller have different surface roughnesses.

10. The device according to claim 1, wherein the frictional force between the first diameter portion of the roller and the electrode plate in contact therewith is different from the frictional force between the second diameter portion of the roller and the electrode plate in contact therewith.

11. A roller for manufacturing a secondary battery electrode plate, the roller being in contact with the electrode plate to convey the electrode plate during the manufacture of a secondary battery, the roller comprising: a first diameter portion having a first diameter; a second diameter portion having a diameter smaller than that of the first diameter portion; and an inclined portion extending between the first diameter portion and the second diameter portion.

12. The roller according to claim 11, wherein the inclined portion of the roller has an inclination angle in the range of 5° to 20°.

13. The roller according to claim 11, wherein the inclined portion of the roller has a length in the range of 1 mm to 3 mm.

14. The roller according to claim 11, wherein the difference between the radii of the first diameter portion and the second diameter portion of the roller is in the range of 100 μm to 350 μm.

15. The roller according to claim 11, wherein the first diameter portion and the second diameter portion of the roller have different surface roughnesses.

16. A method for manufacturing a secondary battery electrode plate, the method comprising: coating an electrode material slurry on a substrate to form an electrode plate; rolling the electrode plate; slitting the rolled electrode plate in the moving direction of the rolled electrode plate; and conveying the corresponding electrode plate among the electrode plate, the rolled electrode plate, and the slit electrode plate by a roller, and the roller being in contact with the corresponding electrode plate, wherein the roller in contact with the electrode plate has a first diameter portion having a first diameter, a second diameter portion having a diameter smaller than that of the first diameter portion, and an inclined portion extending between the first diameter portion and the second diameter portion, and wherein the electrode plate conveyed by the roller has a first thickness portion in contact with the first diameter portion of the roller, a second thickness portion in contact with the second diameter portion of the roller and thicker than the first thickness portion, and a boundary portion between the first thickness portion and the second thickness portion in contact with the inclined portion of the roller.

17. The method according to claim 16, wherein the electrode plate conveyed by the roller is a slit electrode plate formed by slitting the rolled electrode plate, wherein the first thickness portion is an uncoated portion of the slit electrode plate, and wherein the second thickness portion is a coated portion of the slit electrode plate.

18. The method according to claim 16, wherein the electrode plate conveyed by the roller has a third thickness portion between the first thickness portion and the second thickness portion, and Wherein the electrode plate is configured such that the first thickness portion contacts the first diameter portion of the roller, the second thickness portion contacts the second diameter portion of the roller, and the third thickness portion contacts the inclined portion of the roller.

19. The method according to claim 18, wherein the electrode plate conveyed by the roller is the slit electrode plate formed by slitting the electrode plate after roll pressing, wherein the first thickness portion is the uncoated portion of the slit electrode plate, wherein the second thickness portion is the coated portion of the slit electrode plate, and wherein the third thickness portion is the insulating portion of the slit electrode plate.

20. The method according to claim 16, wherein the frictional force between the first diameter portion of the roller and the electrode plate in contact therewith is different from the frictional force between the second diameter portion of the roller and the electrode plate in contact therewith.

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