Electrode and method for manufacturing same

Abstract

An electrode according to an embodiment of the present invention comprises: a base current collector; the porous current collector is laminated on the substrate current collector in layers and is thicker than the substrate current collector; and an active material layer coated on the porous current collector and thicker than the base current collector.

Description

TECHNICAL FIELD

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Korean Patent Application No. 10-2023-0099166, filed on July 28, 2023, in the Republic of Korea, the disclosure of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to an electrode having an active material layer coated on a current collector and a manufacturing method thereof. BACKGROUND

[0004] A secondary battery generally includes an electrode assembly and a case that accommodates the electrode assembly, the electrode assembly accommodated in the case including at least a positive electrode, a separator, and a negative electrode stacked one upon another. Further, each of the positive electrode and the negative electrode can include a current collector and an active material layer coated on at least one surface of the current collector.

[0005] A process for mass-producing a positive electrode or a negative electrode includes the steps of: coating an active material slurry including a binder and a conductive material mixed at an optimal ratio onto at least one surface of an electrode current collector web delivered by a roll-to-roll method; and drying the coated active material slurry to form an active material layer. Through a series of steps, a stacked structure having an active material layer coated on an electrode current collector is formed.

[0006] Subsequently, the stacked structure can be cut into a predetermined size to manufacture an electrode. Further, an electrode assembly can be manufactured by stacking a plurality of electrodes with a separator interposed therebetween.

[0007] In the electrode of the electrode assembly, the amount of the active material coated to the current collector is an important factor that determines the capacity of the secondary battery. That is, as the thickness of the active material layer coated on a predetermined area of the current collector increases, the capacity of the electrode can increase.

[0008] However, when the thickness of the active material layer is very large compared to the thickness of the current collector, the transport path of lithium ions increases, causing the intercalation / deintercalation of lithium ions with the active material far from the current collector, and the movement of electrons through the current collector is limited. Further, the conductive material that provides an electrical path in the electrode is distributed chaotically between the active material and the binder, and as the loading amount of the electrode layer increases, the curvature of the electrical path increases, eventually causing an increase in resistance. That is, the output of the electrode decreases.

[0009] To solve this problem, a method of using a porous current collector having a greater thickness can be considered. However, this method has the following problems: the active material slurry coated to the porous current collector flows down, and it is not easy to groove and weld the electrode tabs. Summary of the Invention

[0010] Technical issues

[0011] This disclosure aims to provide an electrode with high capacity and high output, and a method for manufacturing the same, in which the active material slurry does not flow down during its manufacturing process.

[0012] Technical solution

[0013] An electrode according to an embodiment of the present disclosure may include: a substrate current collector; a porous current collector laminated on the substrate current collector and having a thickness greater than that of the substrate current collector; and an active material layer coated on the porous current collector and having a thickness greater than that of the substrate current collector.

[0014] The substrate current collector may include: a coated portion of the porous current collector layered on top of the substrate; and an uncoated portion connected to the coated portion and protruding further outward compared to the porous current collector and the active material layer.

[0015] A portion of the active material layer can contact the substrate current collector through the porous current collector.

[0016] The thickness of the active material layer can be equal to or greater than the thickness of the porous current collector.

[0017] The porous current collector may include: a first porous current collector, which is laminated on the surface of the substrate current collector; and a second porous current collector, which is laminated on another surface of the substrate current collector. The active material layer may include: a first active material layer coated on the outer surface of the first porous current collector; and a second active material layer coated on the outer surface of the second porous current collector.

[0018] The method for manufacturing an electrode according to embodiments of the present disclosure may include the following steps: stacking a porous current collector on a substrate current collector, wherein the thickness of the porous current collector is greater than the thickness of the substrate current collector; and coating an active material layer on the porous current collector, wherein the thickness of the active material layer is greater than the thickness of the substrate current collector.

[0019] The step of coating an active material layer may include the following steps: applying an active material slurry to a porous current collector; and drying the active material slurry while a portion of it is in contact with a substrate current collector through the porous current collector to form an active material layer.

[0020] The thickness of the active material slurry applied to the porous current collector is equal to or greater than the thickness of the porous current collector.

[0021] The electrode manufacturing method may also include the steps of rolling a substrate current collector, a porous current collector, and an active material layer.

[0022] The substrate current collector may include: a coated portion having a porous current collector layered thereon; and an uncoated portion connected to the coated portion and protruding further outward compared to the porous current collector and the active material layer. The method of manufacturing the electrode may further include the step of slotting the uncoated portion into an electrode connector.

[0023] Beneficial effects

[0024] According to an exemplary embodiment of this disclosure, since the porous current collector is thicker than the substrate current collector, the thickness of the active material layer can be increased without worrying about a decrease in electrode output, thereby increasing the electrode capacity. In other words, the electrode can have both high capacity and high output.

[0025] In addition, the substrate current collector can prevent the active material slurry from flowing down through the porous current collector during the electrode manufacturing process.

[0026] Furthermore, an active material layer can be formed by drying the active material slurry while a portion of it fills multiple pores in the porous current collector. Therefore, the active material layer can be firmly bonded not only to the porous current collector but also to the substrate current collector, thus improving the bond strength between the porous current collector and the substrate current collector.

[0027] Furthermore, the effects of this disclosure may include those readily predictable by those skilled in the art based on the construction of exemplary embodiments of this disclosure. Attached Figure Description

[0028] The accompanying drawings illustrate exemplary embodiments of the present disclosure and are used, together with the following detailed description, to better understand the technical aspects of the present disclosure. Therefore, the present disclosure should not be construed as being limited to the drawings.

[0029] Figure 1 This is a plan view of the electrode according to the first embodiment of the present disclosure.

[0030] Figure 2 yes Figure 1 A sectional view along line A-A'.

[0031] Figure 3 This is a cross-sectional view of an electrode according to a second embodiment of the present disclosure.

[0032] Figure 4 This is a flowchart of a method for manufacturing an electrode according to a third embodiment of the present disclosure.

[0033] Figure 5 This is a schematic diagram illustrating a method for manufacturing an electrode according to a third embodiment of the present disclosure.

[0034] Figure 6 yes Figure 5The plan view of the stacked structure shown. Detailed Implementation

[0035] Hereinafter, exemplary embodiments of the present disclosure will be described in full detail with reference to the accompanying drawings to enable those skilled in the art to readily implement the present disclosure. However, the present disclosure may be embodied in many different forms and is not limited to the following embodiments.

[0036] In order to clearly describe this disclosure, irrelevant descriptions or detailed descriptions of related known technologies that may unnecessarily obscure the essential points of this disclosure have been omitted, and when reference numerals are attached to elements in each figure, the same or similar elements are attached with the same or similar reference numerals throughout the specification.

[0037] Furthermore, the terms or words used in the specification and appended claims should not be construed as limited to their general and dictionary meanings, but rather as being interpreted based on the meanings and concepts corresponding to the technical aspects of this disclosure, on the basis of the principle that the inventors are permitted to properly define the terms for the best interpretation.

[0038] Figure 1 This is a plan view of the electrode according to the first embodiment of the present disclosure. Figure 2 yes Figure 1 A sectional view along line A-A'.

[0039] The electrode 1 according to the first embodiment of the present disclosure may include a substrate current collector 10, a porous current collector 20 stacked on the substrate current collector 10, and an active material layer 30 coated on the porous current collector 20.

[0040] The substrate current collector 10 and the porous current collector 11 can supply electrons from external wires (not shown) to the active material layer 30, or transfer electrons generated as a result of electrode reactions to the external wires.

[0041] The substrate current collector 10 and the porous current collector 20 can comprise any type of highly conductive metal that will not cause any chemical change within the voltage range of the battery. For example, the metal can comprise, but is not limited to, copper, gold, iron, stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel treated on the surface with carbon, nickel, titanium, or silver.

[0042] The substrate current collector 10 can adhere to one surface of the porous current collector 20, and the active material layer 30 can adhere to the other surface of the porous current collector 20.

[0043] The thickness of the substrate current collector 10 can be, for example, from 3 μm to 500 μm, but is not limited to this range.

[0044] The porous current collector 20 can have a three-dimensional network structure. Therefore, the porous current collector 20 can have multiple pores 21 (for convenience, Figure 2 A single pore is shown. Multiple pores 21 can be formed regularly or irregularly. However, the construction of the porous current collector 20 is not limited to this construction.

[0045] The active material layer 30 can be easily adhered to the porous current collector 20. The active material layer 30 can be referred to as the electrode material layer. The active material layer 30 includes an electrode active material and a binder, and may also include a conductive material if desired. Depending on the polarity of the electrode 1, the electrode active material can be a positive electrode active material or a negative electrode active material.

[0046] Positive electrode active materials can include those commonly used in the positive electrode of secondary batteries. For example, positive electrode active materials can include materials such as LiMxOy (M = Co, Ni, Mn, Co...). a Ni b Mn c Lithium transition metal complex oxides (e.g., lithium manganese complex oxides such as LiMn2O4, lithium nickel oxides such as LiNiO2, lithium cobalt oxides such as LiCoO2, and these oxides in which manganese, nickel and cobalt are replaced by other transition metals or lithium vanadium oxides) or chalcogenides (e.g., manganese dioxide, titanium disulfide, molybdenum disulfide).

[0047] The negative electrode active material can include the active materials commonly used in the negative electrode of a secondary battery. For example, the negative electrode active material can include lithium adsorbent materials (such as lithium alloys, carbon, petroleum coke, activated carbon, graphite or other carbons), and can include metal oxides (such as TiO2, SnO2 or Li4Ti5O) with a potential of less than 2V relative to lithium. 12 (but not limited to these).

[0048] Based on the total weight of the electrode active material, the adhesive can be used appropriately in an amount of 1 wt% to 10 wt%, and the conductive material can be used appropriately in an amount of 1 wt% to 30 wt%. Examples of available adhesives may include aqueous adhesives such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinyl acetate, polyethylene oxide, polypyrrolidone, polyvinyl alcohol, polyacrylonitrile, polyacrylic acid (PAA), carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR).

[0049] Conductive materials can typically include carbon black. Currently available commercially available conductive materials include acetylene black (manufactured by Chevron Chemicals or Gulf Oil), Ketjen Black EC (manufactured by Armak), Vulcan XC-72 (manufactured by Cabot), and Super P (manufactured by MMM), as well as linear conductive materials such as carbon nanotubes and carbon (nano)fibers.

[0050] The active material layer 30 can be formed on the porous current collector 20 using common methods. For example, the electrode active material can be mixed with a binder and solvent, and if necessary, mixed with a conductive material and dispersant and stirred to prepare an active material slurry. The active material slurry can then be applied to one surface of the porous current collector 20, followed by compression and drying to form the active material layer 30. The method of applying the active material slurry to the current collector is not limited to a specific method and can include, for example, blade coating, dip-coating, and brush coating.

[0051] The method of removing solvent or dispersant is not limited to a specific method, but may include drying to evaporate the solvent or dispersant as quickly as possible within a range of speeds that do not cause stress concentration, so as to avoid cracking in the active material layer 30 or peeling of the active material layer 30 from the porous current collector 20.

[0052] A portion 30a of the active material layer 30 can contact the substrate current collector 10 through the porous current collector 20. More specifically, since the active material layer 30 is formed by applying an active material slurry to the porous current collector 20, a portion of the active material slurry can fill the plurality of pores 21 of the porous current collector 20. Furthermore, the active material slurry filling the plurality of pores can reach and contact a surface of the substrate current collector 10. A surface of the substrate current collector 10 refers to the surface on which the porous current collector 20 is laminated.

[0053] Therefore, the active material layer 30 can be firmly bonded not only to the porous current collector 20, but also to the substrate current collector 10. Furthermore, the bonding strength between the porous current collector 20 and the substrate current collector 10 can be improved. Thus, peeling of the active material layer 30 due to repeated expansion and contraction during repeated charging and discharging of the battery can be prevented.

[0054] In the absence of a substrate current collector 10 on electrode 1, the active material slurry applied to the porous current collector 20 may flow down through the multiple pores 21 of the porous current collector 20. The substrate current collector 10 can prevent this problem.

[0055] The thickness t2 of the porous current collector 20 can be greater than the thickness t1 of the substrate current collector 10. Therefore, since the porous current collector 20 can be formed with a sufficiently large thickness t2, even if the thickness t3 of the active material layer 30 is increased to increase the capacity of the electrode 1, the output of the electrode 1 can be prevented from decreasing. In other words, by using the porous current collector 20, the thickness t1+t2 of the current collectors 10 and 20 can be prevented from becoming too small compared to the thickness t3 of the active material layer 30.

[0056] The thickness t3 of the active material layer 30 can be greater than the thickness t1 of the substrate current collector 10. The thickness t3 of the active material layer 30 can be equal to or greater than the thickness t2 of the porous current collector 20. Therefore, since the active material layer 30 can be formed with a sufficiently large thickness t3, the capacity of the electrode 1 can be increased.

[0057] Meanwhile, the substrate current collector 10 may include: a coated portion 11 on which a porous current collector 20 is stacked; and an uncoated portion 12 which is connected to the coated portion 11 and protrudes further outward compared to the porous current collector 20 and the active material layer 30.

[0058] The coating portion 11 can be the area that overlaps with the porous current collector 20 and the active material layer 30 in the thickness direction of the electrode 1.

[0059] The uncoated portion 12 can be a region that does not overlap with the porous current collector 20 and the active material layer 30 in the thickness direction of the electrode 1. The uncoated portion 12 can be slotted into an electrode connector with a predetermined shape. The uncoated portion and the electrode connector are substantially the same, and in the following, these two elements are indicated by the same reference numeral "12".

[0060] Therefore, the electrode connector 12 can be easily formed by slotting the substrate current collector 10, which has a relatively small thickness. When forming the electrode connector by slotting the porous current collector 20, it may be difficult to slot due to the large thickness of the porous current collector 20.

[0061] Furthermore, when an electrode assembly is manufactured by stacking multiple electrodes 1, the electrode joints 12 of the multiple electrodes 1 can be welded together. Because each electrode joint 12 is formed by slotting the substrate current collector 10, the electrode joint 12 can have a small thickness, thus making it easy to weld multiple electrode joints 12. In the case where each electrode joint is formed by slotting the porous current collector 20, the thickness of the electrode joint may make it difficult to weld multiple electrode joints.

[0062] Figure 3 This is a cross-sectional view of an electrode according to a second embodiment of the present disclosure.

[0063] The following descriptions that overlap with the foregoing descriptions will be omitted, and the differences in descriptions will be explained.

[0064] In the case of the electrode according to this embodiment, the porous current collector 20 may include a pair of porous current collectors, and the active material layer 30 may include a pair of active material layers.

[0065] More specifically, the porous current collector 20 may include: a first porous current collector 20a laminated on one surface of the substrate current collector 10; and a second porous current collector 20b laminated on the other surface of the substrate current collector 10.

[0066] Furthermore, the active material layer 30 may include: a first active material layer 30a coated on the outer surface of the first porous current collector 20a; and a second active material layer 30b coated on the outer surface of the second porous current collector 20b. The outer surface of each porous current collector 20a, 20b refers to the surface located on the opposite side of the substrate current collector 10.

[0067] With this construction, the capacity and output of the electrode according to this embodiment can be further improved.

[0068] Figure 4 This is a flowchart of a method for manufacturing an electrode according to a third embodiment of the present disclosure. Figure 5 This is a schematic diagram illustrating a method for manufacturing an electrode according to a third embodiment of the present disclosure, and Figure 6 yes Figure 5 The plan view of the stacked structure shown.

[0069] The electrode manufacturing method according to the third embodiment of the present disclosure (hereinafter referred to as the "manufacturing method") may include: a step of stacking a porous current collector 20 on a substrate current collector 10 (S10) (hereinafter referred to as the "stacking step"); and a step of coating an active material layer 30 on the porous current collector 20 (S20) (hereinafter referred to as the "coating step").

[0070] Figure 4 The lamination step (S10) and coating step (S20) are shown to be performed sequentially. However, this disclosure is not limited thereto; the coating step (S20) may be performed before the lamination step (S10), or the lamination step (S10) and coating step (S20) may be performed simultaneously.

[0071] In the lamination step (S10), each of the substrate current collector 10 and the porous current collector 20 can be supplied in a sheet shape with a constant width. In this case, the width W1 of the substrate current collector 10 can be greater than the width of the porous current collector 20. Furthermore, as mentioned above, the porous current collector 20 can be thicker than the substrate current collector 10.

[0072] The porous current collector 20 can be supplied to be laminated on at least one surface of the substrate current collector 10. AlthoughFigure 5 A single porous current collector 20 is shown to be supplied to be laminated on one surface of the substrate current collector 10, but a pair of porous current collectors 20 can be supplied to be laminated on both surfaces of the substrate current collector 10.

[0073] The substrate current collector 10 and the porous current collector 20 can travel at the same speed.

[0074] The coating step (S20) may include: applying an active material slurry to the porous current collector 20 (hereinafter referred to as the "coating step"); and drying the active material slurry to form an active material layer 30 (hereinafter referred to as the "drying step"). The active material slurry and the active material layer are substantially the same, and in the following, these two elements are indicated by the same reference numeral "30".

[0075] In the coating step, the coating machine 110 can continuously or at predetermined intervals apply the active material slurry 30 to the outer surface of the traveling porous current collector 20.

[0076] The thickness of the active material slurry 30 applied to the porous current collector 20 can be greater than the thickness t1 of the substrate current collector 10. The thickness of the active material slurry 30 can be equal to or greater than the thickness t2 of the porous current collector 20.

[0077] The width W2 of the active material slurry 30 applied to the porous current collector 20 can be equal to or similar to the width of the porous current collector 20. Therefore, the width W1 of the substrate current collector 10 can be greater than the width W2 of the active material slurry 30. The portion of the substrate current collector 10 that protrudes further outward compared to the active material slurry 30 can be defined as the uncoated portion 12.

[0078] In the drying step, the active material slurry 30 applied to the porous current collector 20 can be dried while passing through the drying chamber 120, and can form an active material layer 30.

[0079] When the active material slurry 30 dries, a portion of the active material slurry 30 can contact the substrate current collector 10 through the porous current collector 20. That is, the active material slurry 30 can dry while a portion of it fills the multiple pores 21 of the porous current collector 20. Therefore, the active material layer 30 can be firmly bonded not only to the porous current collector 20 but also to the substrate current collector 10. Furthermore, the bonding strength between the porous current collector 20 and the substrate current collector 10 can also be improved.

[0080] When the drying step is completed, a laminated structure 1a comprising a substrate current collector 10, a porous current collector 20, and an active material layer 30 can be manufactured.

[0081] The manufacturing method may also include the step of rolling the substrate current collector 10, the porous current collector 20 and the active material layer 30 (S30) (hereinafter referred to as the "rolling step").

[0082] In the rolling step (S30), the laminated structure 1a can be rolled simultaneously between a pair of pressure rolls 130. Therefore, the substrate current collector 10, the porous current collector 20, and the active material layer 30 can be more firmly connected to each other.

[0083] The manufacturing method may also include a step (S40) of slotting the uncoated portion 12 of the substrate current collector 10 into an electrode connector 12 (hereinafter referred to as the "slotting step").

[0084] A grooving unit (not shown) can groove the uncoated portion 12 into a predetermined shape to form the electrode connector 12. The grooving unit can groove a portion of the edge of the uncoated portion 12 and the coated portion 11 together. The grooving unit can groove along an imaginary grooving line NL, and the area outside the grooving line NL can be cut and removed.

[0085] Electrode connector 12 may be the remaining portion of the uncoated portion 12 after cutting. Electrode connector 12 may be formed at predetermined intervals along the length direction of the laminated structure 1a.

[0086] Subsequently, in subsequent processes, the laminated structure 1a with electrode connector 12 can be cut to a predetermined length to manufacture electrode 1.

[0087] The foregoing description illustrates the technical aspects of this disclosure by way of example, and those skilled in the art to which this disclosure pertains can make various modifications and changes without departing from the essential characteristics of this disclosure.

[0088] Therefore, the disclosed embodiments are provided to describe the technical aspects of this disclosure and are not intended to be limiting, and the technical scope of this disclosure is not limited to these embodiments.

[0089] The scope of protection of this disclosure shall be interpreted by the appended claims, and shall be interpreted as including all technical spirit within the equivalent scope within the scope of protection of this disclosure.

[0090] [List of reference numerals]

[0091] 1: Electrode 1a: Layered structure

[0092] 10: Substrate current collector; 11: Coated part

[0093] 12: Uncoated portion, electrode connector; 20: Porous current collector.

[0094] 30: Active material layer, active material slurry

Claims

1.An electrode comprising: a base current collector; a porous current collector laminated on the base current collector and having a greater thickness than the base current collector; and an active material layer coated on the porous current collector and having a greater thickness than the base current collector. 2.The electrode of claim 1, the base current collector comprises: wherein, a coated portion on which the porous current collector is laminated; and an uncoated portion connected to the coated portion and more outwardly protruding than the porous current collector and the active material layer. 3.The electrode of claim 1, a portion of the active material layer is in contact with the base current collector through the porous current collector. wherein, 4.The electrode of claim 1, a thickness of the active material layer is equal to or greater than a thickness of the porous current collector. wherein 5.The electrode of claim 1, the porous current collector comprises: wherein a first porous current collector laminated on one surface of the base current collector; and a second porous current collector laminated on the other surface of the base current collector, and wherein the active material layer comprises: a first active material layer coated on an outer surface of the first porous current collector; and a second active material layer coated on an outer surface of the second porous current collector. 6.A method of manufacturing an electrode, the method of manufacturing an electrode comprising: laminating a porous current collector on a base current collector, wherein the porous current collector has a greater thickness than the base current collector; and coating an active material layer on the porous current collector, wherein the active material layer has a greater thickness than the base current collector. 7.The method of manufacturing an electrode of claim 6, the step of coating the active material layer comprises: wherein, applying an active material slurry to the porous current collector; and drying the active material slurry in a state in which a portion of the active material slurry is in contact with the base current collector through the porous current collector to form the active material layer. 8.The method of manufacturing an electrode of claim 7, a thickness of the active material slurry applied to the porous current collector is equal to or greater than a thickness of the porous current collector. wherein 9.The method of manufacturing an electrode of claim 6, further comprising: rolling the base current collector, the porous current collector, and the active material layer. 10.The method of manufacturing an electrode of claim 6, the base current collector comprises: wherein a coated portion on which the porous current collector is laminated; and an uncoated portion connected to the coated portion and more outwardly protruding than the porous current collector and the active material layer, and wherein the method of manufacturing an electrode further comprises the step of slitting the uncoated portion into an electrode tab. ​

Images