Secondary battery and method for manufacturing secondary battery

Abstract

A secondary battery and a method of manufacturing the same are provided. The secondary battery includes: an electrode plate substrate; a mixture portion on an outer side of the electrode plate substrate, the mixture portion being a coating layer including an active material; and a hydrophobic coating portion on an outer side of the electrode plate substrate, the hydrophobic coating portion being a coating layer including a hydrophobic material outside a boundary of the mixture portion, and a position of the mixture portion on the outer side of the electrode plate substrate being restricted by the hydrophobic coating portion.

Description

Technical Field

[0001] The present disclosure relates to a secondary battery and a method of manufacturing the secondary battery. Background Art

[0002] Unlike a primary battery that cannot be charged, a secondary battery is a battery that can be charged and discharged. A low-capacity secondary battery can be used for portable small electronic devices, such as smart phones, feature phones, laptop computers, digital cameras, and camcorders, while a high-capacity secondary battery can be used as a power source for driving motors and power storage batteries in hybrid vehicles or electric vehicles. The secondary battery may include an electrode assembly having a positive electrode and a negative electrode, a case accommodating the electrode assembly, electrode terminals connected to the electrode assembly, and the like.

[0003] The above information disclosed in the art as the background of the present disclosure is only for enhancing the understanding of the background of the present disclosure, and thus may include information that does not constitute related art. Summary of the Invention

[0004] Aspects of an embodiment provide a secondary battery including: an electrode plate substrate; a mixture portion on an outer side of the electrode plate substrate, the mixture portion being a coating layer including an active material; and a hydrophobic coating portion on an outer side of the electrode plate substrate, the hydrophobic coating portion being a coating layer including a hydrophobic material outside a boundary of the mixture portion, and a position of the mixture portion on the outer side of the electrode plate substrate being limited by the hydrophobic coating portion.

[0005] The hydrophobic coating portion may be a strip-shaped coating layer on each of opposite sides in a width direction of the electrode plate substrate of the mixture portion.

[0006] The hydrophobic coating portion may include a first material including at least one of nano-silica, fluorinated nano-silica, polyurethane, non-acetic silicone, and fluorocarbon.

[0007] The hydrophobic coating portion may further include a second material that is an ethanol solvent.

[0008] The electrode plate substrate may be a negative electrode, and the mixture portion may include at least one of a conductive material, a binder, an additive, and an active material.

[0009] A thickness of the hydrophobic coating portion may be less than or equal to a thickness of the mixture portion.

[0010] The hydrophobic coating portion may be in direct contact with each of opposite sides in a width direction of the electrode plate substrate of the mixture portion.

[0011] Aspects of the embodiments provide a method of manufacturing a secondary battery, the method including: a supply operation of supplying an electrode plate substrate; a first coating operation of coating an outer side of the electrode plate substrate with a hydrophobic coating portion including a hydrophobic material; and a second coating operation of coating a mixture portion including an active material on the outer side of the electrode plate substrate after the first coating operation.

[0012] In one example, the method may further include a drying operation of drying the hydrophobic coating portion by operating a drying unit after the first coating operation.

[0013] In one example, in the drying operation, a drying method including at least one of heat drying and ultraviolet drying may be included.

[0014] In one example, the method may further include a correction operation of correcting a coating shape of the hydrophobic coating portion between the first coating operation and the drying operation.

[0015] In one example, in the first coating operation, a first material including at least one of nano silica, fluorinated nano silica, polyurethane, non-acetic acid type silicone, and fluorocarbon may be used.

[0016] In one example, in the first coating operation, the first material may be made into a powder form, a slurry may be formed by mixing the first material and a second material used as a solvent, and the slurry may be coated on the electrode plate substrate.

[0017] In one example, in the first coating operation, an adhesive component may be applied to the electrode plate substrate, and then the slurry may be coated on the electrode plate substrate.

[0018] In one example, in the first coating operation, a photosensitive adhesive component may be mixed with the slurry, and then the slurry may be coated on the electrode plate substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Features will become apparent to those skilled in the art by describing exemplary embodiments in detail with reference to the accompanying drawings, where:

[0020] Figure 1 is a cross-sectional view showing a positive electrode, a negative electrode, and a separator of a secondary battery according to an embodiment of the present disclosure.

[0021] Figure 2 is a front view showing an installation state of a coating module and a drying unit according to an embodiment of the present disclosure.

[0022] Figure 3 is a perspective view showing an installation state of a coating module and a drying unit according to an embodiment of the present disclosure.

[0023] Figure 4 is a plan view showing a state in which a hydrophobic coating portion and a mixture portion are formed on an electrode plate substrate according to an embodiment of the present disclosure.

[0024] Figures 5 to 7 is a cross-sectional view, each showing a state in which a hydrophobic coating portion and a mixture portion are formed on an electrode plate substrate according to an embodiment of the present disclosure.

[0025] Figure 8 is a plan view showing a state in which a coating module and a drying unit are installed according to an embodiment of the present disclosure.

[0026] Figure 9 is a plan view showing a state in which a guiding unit is installed between the coating module and the drying unit according to an embodiment of the present disclosure.

[0027] Figure 10 is a plan view showing a state in which the hydrophobic coating portion is aligned through the guiding unit according to an embodiment of the present disclosure.

[0028] Figure 11 is a perspective view showing a state in which a coating module is installed according to another embodiment of the present disclosure.

[0029] Figure 12 is a perspective view showing a coating module according to another embodiment of the present disclosure.

[0030] Figure 13 is a flowchart showing a method of manufacturing a secondary battery according to an embodiment of the present disclosure. Detailed Description

[0031] Hereinafter, example embodiments will be described more fully with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey exemplary implementations to those skilled in the art.

[0032] In the drawings, for clarity of illustration, the dimensions of layers and regions may be exaggerated. It will also be understood that when a layer or element is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals always refer to like elements.

[0033] In addition, as used in this specification, the terms "comprising" or "including" and / or "comprising... of" or "including... of" indicate the presence of the stated shape, quantity, step, operation, component, element, and / or combination thereof, but do not exclude the presence or addition of one or more other shapes, quantities, steps, operations, components, elements, and / or combinations thereof. When used to describe the embodiments of the present disclosure, the terms "may", "might", and "can be" are intended to include one or more embodiments of the present disclosure.

[0034] When two comparison objects are referred to as being the same, this means that the two objects are "substantially the same". Thus, substantially the same can include deviations that are considered to be low in the art, such as deviations of less than 5%. In addition, when a parameter is referred to as being uniform within a certain region, this may mean that the parameter is uniform from an average perspective.

[0035] Although "first", "second", etc. are used to describe various components, these components are of course not limited by these terms. These terms are only used to distinguish one component from other components. Unless otherwise stated, the first component can be referred to as the second component.

[0036] Throughout the specification, unless otherwise specifically stated, each component can be singular or plural.

[0037] When any element is referred to as being "disposed above (or below)" a component or "disposed on (or under)" a component, it not only means that any element is disposed in contact with the upper surface (or lower surface) of the component, but also means that other elements can be interposed between the component and any element disposed on (or under) the component.

[0038] In addition, it should be noted that when a component is described as being "connected" or "coupled" to another component, these components can be directly connected or coupled to each other, but a third component can be interposed between each component, or each component can be connected or coupled to each other through a third component. In addition, when a part is referred to as being electrically connected to another part, this includes not only direct connection, but also connection to other elements disposed between the parts.

[0039] Throughout the specification, the phrase "A and / or B" means (A), (B), or (A and B), unless otherwise stated. That is, the term "and / or" includes all combinations of one or more of the related listed items. The term "C to D" means C or more and D or less, unless otherwise specifically stated.

[0040] Hereinafter, a secondary battery according to an embodiment of the present disclosure will be described with reference to the accompanying drawings.

[0041] Figure 1is a partially enlarged cross-sectional view of an electrode assembly of a secondary battery according to an embodiment of the present disclosure. As Figure 1 shown, the electrode assembly may include a positive electrode 50, a negative electrode 60, and a separator 40 between the positive electrode 50 and the negative electrode 60.

[0042] The secondary battery according to the present embodiment may include one or more electrode assemblies, each of which is wound by inserting a separator 40 as an insulator between the positive electrode 50 and the negative electrode 60. The secondary battery may include a case in which the electrode assembly is inserted and a cover assembly coupled to an opening of the case. The secondary battery according to the present embodiment will be described by way of an example of a prismatic lithium-ion secondary battery. However, any suitable type of secondary battery, such as a lithium polymer battery or a cylindrical battery, may be implemented.

[0043] Referring to Figure 1 , each of the positive electrode 50 and the negative electrode 60 may include a coated portion (i.e., a region where an active material is applied to a current collector formed of a thin metal foil) and an uncoated portion (i.e., a region where the active material is not coated). In the present disclosure, the current collector of the negative electrode 60 may be referred to as an electrode plate substrate 10, and the coated portion of the negative electrode 60 may be referred to as a mixture portion 20.

[0044] For example, the positive electrode 50 and the negative electrode 60 may be wound after inserting the separator 40 as an insulator therebetween to form an electrode assembly. In another example, the electrode assembly may have a structure in which the positive electrode 50 and the negative electrode 60 each including a plurality of sheets are alternately stacked and the separator 40 is interposed therebetween.

[0045] The case may form an overall exterior of the secondary battery and may be formed of a conductive metal, such as aluminum, an aluminum alloy, or nickel-plated steel. In addition, the case may provide a space for accommodating the electrode assembly therein.

[0046] The cover assembly may include a cover plate covering the opening of the case, and the cover plate may be formed of a conductive material. Terminals of the positive electrode 50 and terminals of the negative electrode 60 (which are electrically connected to the positive electrode 50 and the negative electrode 60) may be mounted to protrude outward through the cover plate.

[0047] For example, the outer circumferential surface of an upper post of each of the terminals of the positive electrode 50 and the terminals of the negative electrode 60 protruding to the outside of the cover plate may be threaded and may be fixed to the cover plate with nuts. In another example, the terminals of the positive electrode 50 and the terminals of the negative electrode 60 may have a rivet structure and may be riveted to the cover plate, or may be welded to the cover plate.

[0048] In addition, the cover plate can be formed of a thin plate and can be coupled to the opening of the housing. In the cover plate, an electrolyte inlet to which a sealing cap can be mounted can be formed, and an exhaust portion with a cutout can be mounted. In some examples, the exhaust portion can cover an exhaust hole provided in the cover plate. In some examples, the exhaust portion can be coupled or welded to an area surrounding the exhaust hole (e.g., an area of the cover plate).

[0049] As Figure 1 shown, a hydrophobic coating portion 30 can be formed on the electrode plate substrate 10. For example, as Figure 1 shown, the hydrophobic coating portion 30 can be formed along the periphery of the electrode plate substrate 10 (e.g., along the longitudinal direction of the electrode plate substrate 10) to define the boundary of the mixture portion 20 (e.g., along the width direction of the electrode plate substrate 10), such that the mounting area of the mixture portion 20 of the negative electrode 60 can be located within a set area (e.g., the width direction of the electrode plate substrate 10). The same or similar hydrophobic coating portion can also be applied to the coating portion of the positive electrode 50.

[0050] The mixture portion 20, which is the coating portion of the negative electrode 60, can be a slurry having fluidity. Generally, if the mixture portion decreases in amount due to abnormal process conditions and environment, the mixture portion of the negative electrode facing the end of the coating portion of the positive electrode may become smaller. Therefore, excess lithium ions (Li ions) that are not accepted by the negative electrode during charging may form irreversible products that form an internal short - circuit path with the positive electrode, thus posing a risk of fire. In contrast, according to an embodiment, since the hydrophobic coating portion 30 is mounted at the boundary of the mixture portion 20 to reduce the risk of fire, a decrease in the amount of the mixture in the mixture portion 20 can be prevented or significantly reduced.

[0051] At least one of the electrode plate substrate 10 of the negative electrode 60 and the positive electrode substrate 52 of the positive electrode 50 can be coated with a mixture including an active material, a conductive material, a binder, and an additive. The negative electrode mixture forms the mixture portion 20, and the positive electrode mixture 54 is formed on the positive electrode substrate 52. The negative electrode mixture and the positive electrode mixture 54 can be coated by any suitable method (e.g., a slot - die coating method).

[0052] The electrode plate substrate 10 according to an embodiment of the present disclosure is a current collector of the negative electrode 60, and the mixture portion 20 can include at least one of a conductive material, a binder, an additive, and an active material. The mixture portion 20 can be any suitable mixture including an active material coated on the outer side of the electrode plate substrate 10.

[0053] The mixture portion 20 may be a mixture slurry containing a solvent and powder. If the hydrophobic coating portion 30 is not installed at the boundary of the mixture portion 20 in the slurry state, the end portion of the mixture portion 20 may flow and spread (e.g., toward the outermost edge in the width direction of the electrode plate substrate 10), thereby increasing the width of the end portion of the mixture portion 20 along the width of the electrode plate substrate 10. To prevent the insufficient application of the mixture at the end of the mixture portion 20, the hydrophobic coating portion 30 is coated on the boundary of the mixture portion 20. For example, referring to Figure 1 , the hydrophobic coating portion 30 may be in direct contact with the mixture portion 20, so that the position of the hydrophobic coating portion 30 can determine or define the boundary of the mixture portion 20.

[0054] The slurry for the negative electrode 60 may include distilled water or water and thus has hydrophilicity. Therefore, the hydrophobic coating portion 30 (which is a hydrophobic material or includes a hydrophobic material) may be applied to the position on the electrode plate substrate 10 where the mixture portion 20 (which is the hydrophilic slurry for the negative electrode 60) is not coated or applied. If the hydrophobic coating portion 30 is applied to the electrode plate substrate 10 outside the boundary of the mixture portion 20, after the mixture portion 20 is coated, the resulting mixture slurry for the negative electrode 60 (i.e., the mixture portion 20) having fluidity forms a high contact angle (e.g., a high inclined contact angle) at the coating edge portion. Since the hydrophobic coating portion 30 restricts the hydrophilic mixture portion 20 from moving beyond the hydrophobic coating portion 30, the phenomenon that the thickness of the mixture portion 20 (e.g., measured along the normal of the electrode plate substrate 10) decreases even at the end portion of the mixture portion 20 can be minimized.

[0055] Figure 2 is a front view showing the installation state of the coating module 160 (e.g., a coater) and the drying unit 170 (e.g., a dryer) according to an embodiment of the present disclosure. That is, Figure 2 shows a side view of the arrangement of the coating module 160 and the drying unit 170 relative to the electrode plate substrate 10 and the roller. Figure 3 is a perspective view showing the arrangement of the coating module 160 and the drying unit 170 according to an embodiment of the present disclosure.

[0056] As Figure 2 and Figure 3 shown, within the scope of the technical concept of forming a coating layer including a hydrophobic material on the electrode plate substrate 10 outside the boundary of the mixture portion 20, various modifications can be made to the hydrophobic coating portion 30. For example, referring to Figure 3 , it can be adjusted at the opposite edges of the electrode plate substrate 10 (i.e., at Figure 3At the relative edges along the width W of the electrode plate substrate 10 indicated by the horizontal arrow). Since the hydrophobic coating portion 30 is installed, the change in the width of the mixture portion 20 can be reduced (for example, the diffusion of the mixture portion 20 beyond the hydrophobic coating portion 30 along the width W of the electrode plate substrate 10 can be reduced). That is, the diffusion phenomenon of the mixture portion 20 (which affects the increase in the width of the mixture portion 20 or the dispersion of the mixture portion 20) may be reduced by applying the hydrophobic coating portion 30 (which includes a hydrophobic material) to the negative electrode 60, which is controlled only by the solid content and viscosity of the mixture slurry for the negative electrode 60, thereby increasing the width uniformity and improving the dispersion of the mixture portion 20.

[0057] In the electrode plate substrate 10 of the negative electrode 60, the hydrophobic coating portion 30 can be coated or applied to the boundary of the mixture portion 20. For example, referring to Figure 3 , the hydrophobic coating portion 30 can be linearly applied to the electrode plate substrate 10 in the moving direction or the longitudinal direction D (for example, the hydrophobic coating portion 30 can be continuously applied along the longitudinal direction D of the electrode plate substrate 10 parallel to the edge of the electrode plate substrate 10). By installing the hydrophobic coating portion 30, the phenomenon of the reduction in the amount of the mixture portion 20 when the mixture slurry for the negative electrode 60 having an aqueous (hydrophilic) property diffuses out of the designed coating area can be prevented or substantially minimized.

[0058] For example, the mixture portion 20 can be coated after the hydrophobic coating portion 30 is coated. The hydrophobic coating portion 30 can form a strip-shaped coating layer on each of the two sides of the mixture portion 20 in the width direction W. The hydrophobic coating portion 30 can be coated or applied in a strip shape extending in the longitudinal direction D of the electrode plate substrate 10. The longitudinal direction D of the electrode plate substrate 10 can be the same as the moving direction of the electrode plate substrate 10. The width direction W and the longitudinal direction D can form a right angle.

[0059] The hydrophobic material included in the hydrophobic coating portion 30 should have stable properties so as not to participate in the electrochemical reaction inside the secondary battery. The hydrophobic coating portion 30 according to an embodiment of the present disclosure may include a first material, which includes at least one of nano-silica, fluorinated nano-silica, polyurethane, non-acetic acid type silicone, and fluorocarbon.

[0060] The electrode plate substrate 10 of the negative electrode 60 may include copper. In order to apply the hydrophobic coating portion 30 to the electrode plate substrate 10, a pretreatment can be applied, in which the hydrophobic material in powder form is mixed with a solvent (for example, ethanol) and made into a slurry. In this case, a separate drying process can be added because the slurry-like hydrophobic material may have an adverse effect on the coating quality of the slurry (which is the mixture portion 20).

[0061] The application of the paste-like hydrophobic material can be carried out by a slot coating method, which is the same method as that used for coating the paste-like mixture portion 20. Referring to Figures 2 - 3 , the coating module 160 can be configured to discharge the slurry only when the electrode plate substrate 10 moves. Therefore, if the electrode plate substrate 10 stops moving, the coating module 160 does not operate, so that the over-application of the hydrophobic material to the electrode plate substrate 10 can be prevented or substantially minimized.

[0062] The hydrophobic coating portion 30 according to an embodiment of the present disclosure may further include a second material. The second material may be a solvent to be mixed with the first material. For example, the second material may include ethanol. The first material may include at least one of the hydrophobic materials as described above, such as nano-silica, fluorinated nano-silica, polyurethane, non-acetic acid type silicone, and fluorocarbon.

[0063] To form the mixture portion 20, the electrode plate substrate 10 may be coated with a slurry for the negative electrode 60. The slurry for the negative electrode 60 including a liquid may be cured to form the mixture portion 20. The electrode plate substrate 10 may pass through a plurality of rollers to maintain a constant tension.

[0064] The electrode plate substrate 10 may maintain the tension when passing through the first roller 100 having a pair of rollers and then through the second roller 110 serving as a support roller. The coating module 160 and the drying unit 170 may be installed between the first roller 100 and the second roller 110. For example, the coating module 160 and the drying unit 170 may be adjacent to each other along the longitudinal direction D. The coating module 160 and the drying unit 170 may be installed at positions facing the moving path of the electrode plate substrate 10.

[0065] The hydrophobic material discharged from the coating module 160 may be applied and attached to the electrode plate substrate 10 to form the hydrophobic coating portion 30. The hydrophobic material may be applied and attached while or before the electrode plate substrate 10 passes through the second roller 110 serving as a support roller. The coating of the mixture portion 20 may be carried out after coating the upper surface (based on Figure 2 ) of the electrode plate substrate 10 with the hydrophobic material. If both the upper and lower surfaces of the electrode plate substrate 10 are simultaneously coated with the hydrophobic material and the mixture slurry, contamination of the plurality of rollers may occur when the electrode plate substrate 10 passes through, and deformation of the shape of the hydrophobic coating portion 30 may occur. Therefore, only the upper surface of the electrode plate substrate 10 that does not directly contact the roller is first coated with the hydrophobic material and the mixture slurry, followed by a subsequent process in which the opposite side surface of the electrode plate substrate 10 is coated with the hydrophobic material and the mixture slurry.

[0066] A mixture supply unit 120 (e.g., a mixture supplier) configured to discharge a mixture slurry may be installed on a side surface of the second roller 110 serving as a support roller. For example, the mixture supply unit 120 may be located on a different side of the second roller 110 with respect to the coating module 160 and the drying unit 170 ( Figure 2 ). The mixture supply unit 120 may be any suitable unit for supplying a mixture slurry to the electrode plate substrate 10 to form a mixture portion 20. As Figure 2 shown, the mixture supply unit 120 according to an embodiment of the present disclosure may include a supply head 130, a connection conduit 140, and a control valve 150.

[0067] The supply head 130 may be installed at a position facing the second roller 110. The supply head 130 may supply the mixture slurry to an outer surface of the electrode plate substrate 10 moving along an outer surface of the second roller 110 (i.e., to the same side surface that already includes the hydrophobic coating portion 30). The supply head 130 according to an embodiment of the present disclosure may include a head body 132 installed at a position facing the second roller 110 and an inner tank 134 located inside the head body 132 and configured to store the mixture slurry received through the connection conduit 140. The supply head 130 may include an inner conduit 136 extending from the inner tank 134 in a direction toward the second roller 110. For example, as Figure 2 shown, the inner tank 134 and the inner conduit 136 may be in fluid communication with each other. For example, an outlet of the inner conduit 136 may face and overlap a central region of the electrode plate substrate 10 between the hydrophobic coating portions 30 at an edge of the electrode plate substrate 10.

[0068] The connection conduit 140 may extend into the head body 132 (e.g., inside the head body 132) and may be connected to the inner tank 134. The amount of the mixture slurry passing through the connection conduit 140 may be adjusted by an operation of the control valve 150 connected to the connection conduit 140. The inner tank 134 forms a space for storing the mixture slurry inside the head body 132. The mixture slurry stored in the inner tank 134 may move through the inner conduit 136 communicating with the inner tank 134 and then be applied to an outer side of the electrode plate substrate 10.

[0069] The coating module 160 may be installed between the first roller 100 and the second roller 110 and may be installed above the electrode plate substrate 10 moving from the first roller 100 to the second roller 110. The coating module 160 may receive a hydrophobic slurry and apply the hydrophobic slurry to an upper side (e.g., an outer side) of the electrode plate substrate 10 to form a hydrophobic coating portion 30. The structure of the coating module 160 may be the same as the structure of the mixture supply unit 120.

[0070] The drying unit 170 may be installed at a position facing the electrode plate substrate 10 passing through the coating module 160 to dry the hydrophobic slurry discharged from the coating module 160. The drying unit 170 may dry the hydrophobic slurry using, for example, at least one of heat drying and ultraviolet drying to form the hydrophobic coating portion 30.

[0071] As Figure 3 shown, the coating module 160 may be installed on each of the two sides of the electrode plate substrate 10 in the width direction W. For example, the coating module 160 may be installed to face and perpendicularly overlap the peripheral edges of each of the opposite sides of the electrode plate substrate 10 in the width direction W. The drying unit 170 may also be installed on each of the two sides of the electrode plate substrate 10 in the width direction W. For example, the drying unit 170 may be installed adjacent to the coating module 160 to face and perpendicularly overlap the peripheral edges of each of the opposite sides of the electrode plate substrate 10 in the width direction W. Based on the coating module 160, the drying unit 170 may be installed on the rear side of the electrode plate substrate 10 in the longitudinal direction D. For example, the drying unit 170 may be located between the coating module 160 and the second roller 110 in the longitudinal direction D. Thus, the slurry including the hydrophobic material and discharged from the coating module 160 to the electrode plate substrate 10 may be dried by the drying unit 170 so that the roller may not be contaminated in the post-treatment.

[0072] Figure 4 is a view showing a state in which the hydrophobic coating portion 30 and the mixture portion 20 are formed on the electrode plate substrate 10 according to an embodiment of the present disclosure. That is, Figure 4 is a plan view showing a part of the electrode plate substrate 10 coated with the hydrophobic coating portion 30 and the mixture portion 20.

[0073] As Figure 4 shown, the strip-shaped hydrophobic coating portion 30 extending in the longitudinal direction D may be coated (e.g., positioned) on each of the two sides of the electrode plate substrate 10 in the width direction W. The end portions of the hydrophobic coating portion 30 and the end portions of the electrode plate substrate 10 may be spaced apart from each other by a set distance in the width direction W to form an uncoated portion.

[0074] The hydrophobic coating portion 30 may be installed (e.g., coated or deposited) on each of the two sides of the mixture portion 20 in the width direction W. After the hydrophobic coating portion 30 is first coated, the mixture slurry for forming the mixture portion 20 may be applied to the electrode plate substrate 10 between the two hydrophobic coating portions 30. For example, as Figure 4As shown, the mixture portion 20 can be restricted (e.g., defined, blocked, or surrounded) between two hydrophobic coating portions 30. The mixture slurry with fluidity can be installed only in the area defined by the hydrophobic coating portions 30 (i.e., between the two hydrophobic coating portions 30).

[0075] Figures 5 to 7 are cross-sectional views, each showing a state in which the hydrophobic coating portion 30 and the mixture portion 20 are formed on the electrode plate substrate 10 according to an embodiment of the present disclosure.

[0076] As Figure 5 shown, the shape and the end contact angle of the mixture slurry for the negative electrode 60 can be adjusted according to the applied thickness or the coating thickness of the hydrophobic coating portion 30, so that the end portion contact angle and the shape of the mixture portion 20 can be adjusted. Since the shape of the mixture portion 20 can be controlled, the charge / discharge performance of the secondary battery can be optimized.

[0077] The hydrophobic material used in the hydrophobic coating portion 30 has stability, so that it does not participate in the electrochemical reaction inside the secondary battery, thereby maintaining the stability of the secondary battery.

[0078] The applied thickness of the hydrophobic coating portion 30 should be less than the coating height of the mixture slurry with fluidity and can have a level similar to the target height of the mixture portion 20 in the rolling process. If the hydrophobic coating portion 30 is applied thicker than the mixture slurry for the negative electrode 60, the hydrophobic coating portion 30 may be squeezed by the rolling roller and may cover the upper side of the mixture portion 20. Therefore, if the charge and discharge operations are performed, the charge / discharge performance may be reduced due to interference with the movement of lithium ions (Li ions). The thickness of the hydrophobic coating portion 30 according to an embodiment of the present disclosure can be less than or equal to the thickness of the mixture portion 20.

[0079] The two end portions of the mixture portion 20 in the width direction W can change in shape according to the height of the hydrophobic coating portion 30. If the height of the hydrophobic coating portion 30 is 20% or less of the height of the mixture portion 20, the contact angle of the mixture portion 20 increases. The contact angle is the angle formed between the inclined surface of the end portion of the mixture portion 20 in the width direction W and the electrode plate substrate 10.

[0080] As Figure 6 shown, if the height of the hydrophobic coating portion 31 increases, the contact angle of the mixture portion 20 decreases. As Figure 7 shown, if the height of the hydrophobic coating portion 32 increases to slightly lower than the height of the mixture portion 20, the contact angle of the mixture portion 20 can be Figure 6The contact angle therein is further reduced. The shape of the mixture slurry at the coated edge portion of the electrode plate substrate 10 can be determined by the contact angle formed between the slurry and the electrode plate substrate 10.

[0081] Figure 8 is a plan view showing a state in which a coating module 160 and a drying unit 170 according to an embodiment of the present disclosure are installed. As Figure 8 shown, the hydrophobic coating portion 30 can be dried by the drying unit 170 using at least one of heat drying and ultraviolet drying. If it is assumed that the electrode plate substrate 10 moves upward in the longitudinal direction D (based on Figure 8 ), then the drying unit 170 can be installed above the coating module 160 in the longitudinal direction D.

[0082] Figure 9 is a plan view showing a state in which a guiding unit 180 is installed between the coating module 160 and the drying unit 170 according to an embodiment of the present disclosure, Figure 10 is a plan view showing a state in which the hydrophobic coating portion 30 is aligned by the guiding unit 180 according to an embodiment of the present disclosure. As Figure 9 and Figure 10 shown, the hydrophobic slurry ejected from the coating module 160 may not be in a straight shape. Therefore, the guiding unit 180 can be installed between the coating module 160 and the drying unit 170, and can correct the shape of the hydrophobic coating portion 30. For example, the shape of the hydrophobic coating portion 30 can be made linear. The installation of the guiding unit 180 can improve the uniformity of the hydrophobic slurry on the upper side of the substrate base applied to the negative electrode 60 or the hydrophobic material applied on the photosensitive adhesive or the adhesive component, thereby improving the clarity and accuracy of the boundary of the hydrophobic coating portion 30.

[0083] According to an embodiment of the present disclosure, the guiding unit 180 may include a first guide 182 and a second guide 184. The first guide 182 is installed on one side of the hydrophobic coating portion 30 facing the moving path in the width direction W, and the second guide 184 is installed at a position facing the first guide 182 with the hydrophobic coating portion 30 interposed therebetween. The hydrophobic coating portion 30 may be located between the first guide 182 and the second guide 184, and the inlets and outlets of the first guide 182 and the second guide 184 are installed to be spaced apart from each other. The guiding unit 180 may be installed in a fixed state together with the coating module 160. In the first guide 182 and the second guide 184, the inlet width (length) L1 may be greater than the outlet width (length) L2. Since the inlet of the guiding unit 180 is wider than the outlet in width, the hydrophobic coating portion 30 moving from the inlet of the guiding unit 180 to the outlet of the guiding unit 180 may be corrected in shape to a straight shape extending in the longitudinal direction D while having a width equal to the outlet width of the guiding unit 180.

[0084] According to the present disclosure as shown above, the installation of the hydrophobic coating portion 30 can prevent the diffusion of the mixture portion 20, so that the mixture portion 20 can be uniformly installed and the energy density can be increased. In addition, the insufficient amount of the mixture portion 20 at the boundary of the mixture portion 20 can be prevented or substantially minimized, so that the charge / discharge performance of the secondary battery can be improved and the productivity can be increased.

[0085] Figure 13 is a flowchart showing a method of manufacturing a secondary battery according to an embodiment of the present disclosure. As Figure 13 shown, a method of manufacturing an exemplary secondary battery according to an embodiment of the present disclosure may include a supply operation (S10) of supplying the electrode plate substrate 10. The electrode plate substrate 10 may be moved through the first roller 100 and the second roller 110.

[0086] After the supply operation, a first coating operation (S20) of coating the electrode plate substrate 10 with the hydrophobic coating portion 30 containing a hydrophobic material may be performed. In the first coating operation (S20), a first material including at least one of nano-silica, fluorinated nano-silica, polyurethane, non-acetic acid type silicone, and fluorocarbon may be used. In the first coating operation (S20), the first material may be made into a powder form and then mixed with a second material used as a solvent to form a slurry, and then the slurry may be applied to the electrode plate substrate 10.

[0087] In the first coating operation (S20), after applying an adhesive component on the electrode plate substrate 10, the electrode plate substrate 10 may be coated with the slurry. A polymer adhesive such as polyurethane, polyacrylate, epoxy resin, etc. may be used as the adhesive.

[0088] In the first coating operation (S20), after mixing the photosensitive binder component into the slurry, the slurry can be applied to the electrode plate substrate 10. A polymer binder can be used as the photosensitive binder. When applying the hydrophobic material, the photosensitive binder component can be applied to the electrode plate substrate 10, and then the hydrophobic material in powder form can be further attached to the photosensitive binder component, thereby forming the hydrophobic coating portion 30. Alternatively, the hydrophobic material in a state where the photosensitive binder component and the hydrophobic material in powder form are mixed can be applied to the electrode plate substrate 10 by a slot coating method.

[0089] Between the first coating operation and the drying operation, a correction operation (S30) for correcting the coating shape of the hydrophobic coating portion 30 can be further included. The hydrophobic coating portion 30 discharged from the coating module 160 and applied to the electrode plate substrate 10 can be corrected in shape when passing through the guiding unit 180 including the first guiding member 182 and the second guiding member 184.

[0090] After the correction operation (S30), a drying operation (S40) for operating the drying unit 170 to dry the hydrophobic coating portion 30 can be further included. The drying operation (S40) can be performed by a drying method using at least one of heat drying and ultraviolet drying. The hydrophobic coating portion 30 that has passed through the guiding unit 180 or has been applied by the coating module 160 can be dried while passing through the drying unit 170.

[0091] After the first coating operation (S20), a second coating operation (S50) for applying the mixture portion 20 containing the active material to the outer side of the electrode plate substrate 10 can be included. After drying the hydrophobic coating portion 30 is completed, the mixture slurry can be applied to the electrode plate substrate 10 through the mixture supply unit 120 to form the mixture portion 20. The shape of the end portion of the mixture portion 20 can be controlled according to the height of the hydrophobic coating portion 30 without intruding into the area of the hydrophobic coating portion 30.

[0092] Figure 11 is a perspective view showing a state in which a coating module 260 according to another embodiment of the present disclosure is installed, Figure 12 is an enlarged perspective view showing a coating module 260 according to another embodiment of the present disclosure. As Figure 11 and Figure 12As shown, the coating module 260 according to another embodiment of the present disclosure can be variously modified within the technical idea of applying a hydrophobic slurry and a photosensitive adhesive or an adhesive component material to the electrode plate substrate 10. The coating module 260 according to another embodiment of the present disclosure may include a first coating head 262, a first conduit 264, a first tank 266, a first nozzle 268, a second coating head 272, a second conduit 274, a second tank 276, and a second nozzle 278. The main body of the coating module 260 includes the first coating head 262 and the second coating head 272.

[0093] A first tank 266 configured to store a hydrophobic slurry may be provided within the first coating head 262. The hydrophobic slurry may be transferred to the first tank 266 through the first conduit 264 connected to the first tank 266. The first nozzle 268 extending from the first tank 266 may extend from the first tank 266 to the outlet of the first coating head 262. Accordingly, the hydrophobic slurry moving from the first tank 266 to the first nozzle 268 is discharged toward the electrode plate substrate 10.

[0094] A second tank 276 configured to store a photosensitive adhesive or an adhesive component material may be provided within the second coating head 272, facing the first coating head 262. The photosensitive adhesive or the adhesive component material may be transferred to the second tank 276 through the second conduit 274 connected to the second tank 276. The second nozzle 278 extending from the second tank 276 may extend from the second tank 276 to the outlet of the second coating head 272. Accordingly, the photosensitive adhesive or the adhesive component material moving from the second tank 276 to the second nozzle 278 may be discharged toward the electrode plate substrate 10.

[0095] The photosensitive adhesive or the adhesive component material may be applied to the electrode plate substrate 10 through the second nozzle 278 to form an adhesive layer 300, and then the hydrophobic slurry may be applied to the electrode plate substrate 10 through the first nozzle 268, thereby forming a hydrophobic coating portion 30. A polymer adhesive, such as polyurethane, polyacrylate, epoxy resin, etc., may be used as the adhesive or the photosensitive adhesive.

[0096] By summarizing and reviewing, the present disclosure provides a secondary battery and a method of manufacturing a secondary battery, which allows the mixture applied to the electrode plate to be uniformly applied. That is, according to the present disclosure, the diffusion of the mixture portion (i.e., the coating layer on the coating portion of the current collector of the electrode) can be prevented by installing the hydrophobic coating portion, so that the mixture portion can be uniformly installed and the energy density can be increased. In addition, the insufficient amount of the mixture portion at the boundary of the mixture portion can be prevented or substantially minimized, thereby improving the charge / discharge performance of the secondary battery and increasing the productivity.

[0097] However, the technical problems to be solved by the present disclosure are not limited to the above problems, and those skilled in the art will clearly understand other problems not described from the description.

[0098] Example embodiments have been disclosed herein. Although specific terms are employed, they are used and interpreted in a general and descriptive sense only and not for the purpose of limitation. In some instances, as will be apparent to those of ordinary skill in the art at the time of filing of this application, unless otherwise specifically stated, features, characteristics, and / or elements described in connection with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in connection with other embodiments. Accordingly, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope of the present disclosure as set forth in the appended claims.

[0099] This application claims the priority and benefit of Korean Patent Application No. 10-2023-0165289, filed with the Korean Intellectual Property Office on November 24, 2023, the content of which is incorporated herein by reference in its entirety.

Claims

1. A secondary battery comprising: Electrode plate substrate; a mixture portion on the outer side of the electrode plate substrate, the mixture portion being a coating layer including an active material; as well as A hydrophobic coating portion on the outer side of the electrode plate substrate is a coating layer including a hydrophobic material outside a boundary of the mixture portion, and a position of the mixture portion on the outer side of the electrode plate substrate is limited by the hydrophobic coating portion. 2 . The secondary battery according to claim 1 , wherein the hydrophobic coating portion is a band-shaped coating layer on each of opposite sides of the mixture portion in a width direction of the electrode plate substrate. 3 . The secondary battery according to claim 1 , wherein the hydrophobic coating portion comprises a first material comprising at least one of nano-silica, fluorinated nano-silica, polyurethane, non-acetate siloxane, and fluorocarbon. 4 . The secondary battery according to claim 3 , wherein the hydrophobic coating portion further comprises a second material, and the second material is an ethanol solvent.

5. The secondary battery according to claim 1, wherein: The electrode plate substrate is a negative electrode, and The mixture part includes at least one of a conductive material, a binder, an additive and the active material. 6 . The secondary battery according to claim 1 , wherein a thickness of the hydrophobic coating portion is less than or equal to a thickness of the mixture portion. 7 . The secondary battery according to claim 1 , wherein the hydrophobic coating portion is in direct contact with each of opposite sides of the mixture portion in a width direction of the electrode plate substrate.

8. A method for manufacturing a secondary battery, the method comprising: Supplying operation of supplying electrode plate substrate; a first coating operation of coating the outer side of the electrode plate substrate with a hydrophobic coating portion, the hydrophobic coating portion comprising a hydrophobic material; as well as A second coating operation of coating a mixture part on the outer side of the electrode plate substrate, the mixture part including an active material, the second coating operation being performed after the first coating operation. 9 . The method of claim 8 , further comprising a drying operation of drying the hydrophobic coating portion by operating a drying unit after the first coating operation.

10. The method according to claim 9, wherein the drying operation comprises at least one of heat drying and ultraviolet drying. 11 . The method according to claim 9 , further comprising a correction operation of correcting a shape of the hydrophobic coating portion between the first coating operation and the drying operation.

12. The method according to claim 8, wherein in the first coating operation, a first material comprising at least one of nano-silica, fluorinated nano-silica, polyurethane, non-acetate siloxane, and fluorocarbon is used.

13. The method of claim 12, wherein in the first coating operation: preparing the first material into powder form, forming a slurry by mixing the first material and a second material serving as a solvent, and The slurry is coated on the electrode plate substrate.

14. The method of claim 13, wherein in the first coating operation: applying an adhesive component to the electrode plate substrate, and The slurry is coated on the electrode plate substrate.

15. The method of claim 13, wherein in the first coating operation: mixing a photosensitive adhesive component with the slurry, and The slurry is coated on the electrode plate substrate.

Images