Electrode stack and method for manufacturing an electrode stack

Abstract

This disclosure aims to provide an electrode laminate that is less susceptible to brittle fracture. [Solution] An electrode laminate 100 having a current collector layer 110 and an electrode active material layer 120 laminated on a part of the current collector layer, wherein the current collector layer 110 has a conductor layer 111 and a first carbon coating layer 112 laminated on at least a part of the conductor layer 111, the electrode active material layer 120 is laminated on at least a part of the first carbon coating layer 112, and in an adjacent region 200 adjacent to the electrode active material layer 120, the current collector layer 110 does not have the first carbon coating layer 112, or has a second carbon coating layer 113 which has a lower absorption rate of 970 nm laser light than the first carbon coating layer 112.

Description

[Technical Field]

[0001] This disclosure relates to an electrode stack and a method for manufacturing an electrode stack. [Background technology]

[0002] It is known that a carbon coating layer is laminated between the current collector layer and the electrode active material layer of an electrode laminate to reduce internal resistance. Various disclosures have been made regarding the composition of the carbon coating layer.

[0003] Patent Document 1 discloses a current collector foil comprising a metal foil, a carbon coating layer containing carbon particles laminated on the surface of the metal foil, and an active material layer containing an active material laminated on the surface of the carbon coating layer, wherein the carbon coating layer has a surface roughness Ra of 0.5 μm to 1.0 μm. Patent Document 1 states that, according to the disclosure in Patent Document 1, it is possible to suppress interfacial delamination between the carbon coating layer and the active material layer of the current collector foil and to improve battery characteristics.

[0004] Patent Document 2 discloses a carbon coating layer provided on a current collector, characterized in that the carbon material irregularities are provided on the side that comes into contact with the active material. Patent Document 2 states that, according to the disclosure in Patent Document 2, by forming irregularities on the current collector with a carbon material, the adhesion between the active material and the current collector is improved without impairing the amount of active material filled, internal resistance can be reduced, and excellent characteristics in charge-discharge cycles can be obtained without reducing the capacity of the battery.

[0005] On the other hand, laser irradiation is known as a drying and molding method for electrode slurry layers coated on current collector layers. In particular, drying electrode slurry by laser irradiation has the advantage of consuming less energy and having a lower environmental impact compared to drying with hot air.

[0006] Patent Document 3 discloses an electrode shape control method that includes a molding step in which a laser is irradiated onto at least a portion of an electrode sheet coated with electrode slurry, and the electrode slurry in the laser-irradiated area is moved to an adjacent area to shape the electrode slurry. Patent Document 3 states that, according to the disclosure in Patent Document 3, it is possible to provide an electrode shape control method and an electrode manufacturing method that can control the shape of the electrode after electrode coating while minimizing capacitance loss.

[0007] Patent Document 4 discloses an electrode manufacturing method comprising: a transport step of transporting an electrode body coated with at least one electrode material by a transport unit; and a drying step of drying the electrode material while transporting the electrode body by the transport unit, wherein the drying step includes an irradiation step of drying the electrode material by irradiating it with a laser when the electrode body is transported to at least one first position in the transport direction of the transport unit; and a recovery step of recovering the vapor generated as a result of the laser irradiation of the electrode material by a vapor recovery unit provided at least one second position adjacent to the first position in the transport direction. Patent Document 4 states that, according to the disclosure in Patent Document 4, it is possible to suppress a decrease in drying efficiency when drying the electrode material with a laser. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2010-212167 [Patent Document 2] Japanese Patent Publication No. 2015-088333 [Patent Document 3] Special Publication 2024-518633 [Patent Document 4] Japanese Patent Publication No. 2023-169591 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The electrode laminate is manufactured by applying an electrode mixture slurry onto a carbon coating layer of a current collector layer and heating and drying the electrode mixture slurry by light irradiation such as laser irradiation. When irradiating the electrode mixture slurry with light, it is difficult to irradiate only the electrode mixture slurry, and the adjacent carbon coating layer is also irradiated with light. Since the carbon coating layer has a high light absorption rate, it becomes high temperature, and the heat is transferred to the end of the electrode mixture slurry. As a result, the evaporation rate of the volatile substances in the electrode mixture slurry increases, the vapor pressure in the electrode mixture slurry becomes high, and cracks are likely to occur in the electrode active material layer formed by drying. Therefore, the electrode laminate is likely to undergo brittle fracture.

[0010] Therefore, an object of the present disclosure is to provide an electrode laminate in which brittle fracture hardly occurs.

Means for Solving the Problems

[0011] The present disclosure achieves the above object by the following means. <Aspect 1> An electrode laminate having a current collector layer and an electrode active material layer laminated on a part of the current collector layer, The current collector layer has a conductor layer and a first carbon coating layer laminated on at least a part of the conductor layer, The electrode active material layer is laminated on at least a part of the first carbon coating layer, In an adjacent region adjacent to the electrode active material layer, the current collector layer does not have a first carbon coating layer or has a second carbon coating layer having a lower absorption rate of 970 nm wavelength laser light than the first carbon coating layer. Electrode laminate. <Aspect 2> The electrode laminate according to Aspect 1, wherein the electrode active material layer is laminated only on a part of the first carbon coating layer. <Aspect 3> The electrode laminate according to Aspect 1 or 2, wherein the first carbon coating layer on which the electrode active material layer is not laminated is disposed at a peripheral portion of the current collector layer. <Aspect 4> The electrode laminate according to any one of embodiments 1 to 3, wherein the absorption rate of the current collector layer with a wavelength of 970 nm laser light in the adjacent region is 40% or less. <Aspect 5> Laminating an electrode composite slurry layer on at least a portion of the first carbon coating layer, and The electrode composite slurry layer, which is laminated on at least a portion of the first carbon coating layer, and the adjacent region are irradiated with laser light to dry the electrode composite slurry layer and form an electrode active material layer. A method for manufacturing an electrode laminate according to any one of embodiments 1 to 4, including the method described in any one of embodiments 1 to 4. [Effects of the Invention]

[0012] According to this disclosure, it is possible to provide an electrode laminate that is less prone to brittle fracture. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a front cross-sectional view illustrating the electrode stack of this disclosure. [Figure 2] Figure 2 is a top view illustrating the electrode stack of this disclosure. [Figure 3] Figure 3 is a schematic diagram illustrating the examples and comparative examples. [Figure 4] Figure 4 is a schematic diagram illustrating the examples and comparative examples. [Modes for carrying out the invention]

[0014] Electrode Stack The electrode stack in this disclosure is An electrode laminate having a current collector layer and an electrode active material layer laminated on a part of the current collector layer, The current collector layer has a conductive layer and a first carbon coating layer laminated on at least a portion of the conductive layer. The electrode active material layer described above is laminated on at least a portion of the first carbon coating layer described above. In an adjacent region adjacent to the electrode active material layer, the current collector layer either does not have a carbon coating layer, or has a second carbon coating layer that has a lower absorption rate of 970 nm laser light than the first carbon coating layer.

[0015] According to this disclosure, it is possible to provide an electrode laminate that is less prone to brittle fracture.

[0016] If the adjacent region does not have a carbon coating layer, or if the adjacent region has a carbon coating layer with high reflectivity, even if light energy is supplied to the adjacent region along with the electrode mixture slurry during drying, the adjacent region will not overheat, and heat transfer to the edge of the electrode mixture slurry will be suppressed. Therefore, cracks will not occur in the electrode active material layer, resulting in an electrode laminate that is less susceptible to brittle fracture.

[0017] Specifically, for example, as shown in Figure 1(a), the electrode laminate 100 of this disclosure has a current collector layer 110 and an electrode active material layer 120 laminated on a part of the current collector layer 110. Here, the current collector layer 110 has a conductor layer 111 and a first carbon coating layer 112, with the first carbon coating layer 112 laminated on a part of the conductor layer 111. The electrode active material layer 120 is laminated on a part of the first carbon coating layer 112. The first carbon coating layer 112 is not laminated on the conductor layer 111 in the adjacent region 200 of the electrode active material layer 120. Also, as shown in Figure 1(b), a second carbon coating layer 113 with a low laser light absorption rate may be laminated on the conductor layer 111 in the adjacent region 200. Note that Figure 2(a) is a top view of Figure 1(a), and Figure 2(b) is a top view of Figure 1(b).

[0018] The embodiments of this disclosure will be described in detail below. However, this disclosure is not limited to the embodiments described below and can be implemented in various ways within the scope of the gist of this disclosure.

[0019] The electrode laminate of this disclosure has a current collector layer and an electrode active material layer laminated on a portion of the current collector layer. The electrode laminate may also be a bipolar electrode laminate having a positive electrode active material layer and a negative electrode active material layer.

[0020] The electrode active material layer is laminated on at least a portion of the first carbon coating layer. Laminating the electrode active material layer on the carbon coating layer reduces internal resistance. Alternatively, the electrode active material layer may be laminated on only a portion of the first carbon coating layer.

[0021] <Current collector layer> The current collector layer comprises a conductive layer and a carbon coating layer laminated over at least a portion of the conductive layer.

[0022] In an adjacent region adjacent to the electrode active material layer, the current collector layer either does not have a first carbon coating layer, or has a second carbon coating layer that has a lower absorption rate of 970 nm laser light than the first carbon coating layer.

[0023] In this specification, "adjacent region" means a region outside the electrode active material layer that is adjacent to the electrode active material layer, within 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, or 100 mm from the edge of the electrode active material layer in the longitudinal and width directions of the electrode active material layer, as shown in Figures 1 and 2.

[0024] In adjacent regions, the absorption rate of the current collector layer with 970nm laser light may be 40% or less. Alternatively, the absorption rate of the current collector layer with 970nm laser light may be 35% or less, 30% or less, 25% or less, or 20% or less, and may be 0% or more, 5% or more, 10% or more, or 15% or more.

[0025] The first carbon coating layer, which does not have an electrode active material layer laminated on it, may be arranged on the periphery of the current collector layer. When multiple electrode stacks of this disclosure are stacked to form an energy storage module for a bipolar battery, having such a configuration can improve the adhesion between the periphery of the current collector layer having the carbon coating layer and a sealing member such as resin, thereby improving the sealing performance of the periphery.

[0026] The current collector layer may be a positive electrode current collector layer or a negative electrode current collector layer.

[0027] (Carbon coating layer) In this specification, "first carbon coating layer" means a carbon coating layer with a high laser light absorption rate. The laser light absorption rate (%) of the first carbon coating layer is not particularly limited and may be 50% or more, 60% or more, or 70% or more for laser light with a wavelength of 970 nm, or it may be 100% or less, 90% or less, or 80% or less.

[0028] In this specification, "second carbon coating layer" means a carbon coating layer with a lower laser light absorption rate than the first carbon coating layer. The laser light absorption rate (%) of the first carbon coating layer is not particularly limited and may be 5% or more, or 10% or more, for example, 40% or less, 35% or less, 30% or less, 25% or less, or 20% or less for laser light with a wavelength of 970 nm.

[0029] The laser light absorption rate (-) can be measured by spectrophotometric method using an ultraviolet-visible-near-infrared spectrophotometer (Shimadzu Corporation, SolidSpec-3700DUV).

[0030] The carbon coating layer's laser light absorption rate can be adjusted by rubbing its surface with a non-woven fabric or similar material; in particular, rubbing the surface with a non-woven fabric or similar material can reduce the laser light absorption rate.

[0031] The carbon coating layer may contain at least carbon particles and may also contain a binder, dispersant, etc. For details on the binder, refer to the description of the electrode active material layer below. Examples of dispersants include carboxyethyl cellulose. The content of carbon particles, binder, dispersant, etc., may be appropriately determined depending on the performance required of the carbon coating layer.

[0032] The shape of the carbon coating layer is not particularly limited and may be, for example, a sheet. The thickness of the carbon coating layer is not particularly limited and may be, for example, 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, or 0.5 μm or more, or 5.0 μm or less, 3.0 μm or less, 2.0 μm or less, or 1.0 μm or less.

[0033] (Conductive layer) The material of the conductive layer is not particularly limited, but commonly used conductors for batteries can be appropriately adopted. When the current collector layer is the positive electrode current collector layer, examples of conductive layer materials include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, etc. When the current collector layer is the negative electrode current collector layer, examples of conductive layer materials include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, or carbon sheets, etc. Furthermore, the conductive layer may be a metal foil or a substrate on which the above metals are plated or vapor-deposited.

[0034] The shape of the conductive layer is not particularly limited, but examples include foil-like, plate-like, or mesh-like shapes. Among these, a foil-like shape is preferred.

[0035] The thickness of the conductive layer is not particularly limited, but may be 0.1 μm or more, or 1 μm or more, or 1 mm or less, or 100 μm or less.

[0036] <Electrode active material layer> The electrode active material layer may be a positive electrode active material layer or a negative electrode active material layer. When the current collector layer is a positive electrode current collector layer, the positive electrode active material layer is laminated on the first carbon coat layer. When the current collector layer is a negative electrode current collector layer, the negative electrode active material layer is laminated on the first carbon coat layer.

[0037] The shape of the electrode active material layer is not particularly limited, but may be, for example, a sheet with a substantially flat surface. The thickness of the electrode active material layer is not particularly limited, but may be, for example, 0.1 μm or more, 1 μm or more, 10 μm or more, or 100 μm or more, or 2.0 mm or less, 1.0 mm or less, or 0.5 mm or less.

[0038] The electrode active material layer contains at least a positive electrode active material or a negative electrode active material, and may further optionally contain a binder, a solid electrolyte, and a conductive additive. The electrode active material layer may also contain various other additives. The respective content of the positive electrode active material, negative electrode active material, solid electrolyte, conductive additive, etc. in the electrode active material layer should be appropriately determined according to the desired battery performance.

[0039] (Cathode active material) The material of the positive electrode active material is not particularly limited as long as it is capable of intercalating and releasing lithium ions. Examples of positive electrode active materials include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMn2O4), and nickel-cobalt-manganese oxide (NCM:LiCO2). 1 / 3 Ni 1 / 3 Mn 1 / 3 O2), lithium nickel-cobalt aluminum oxide (LiNi 0.8 (CoAl) 0.2 O2), Li 1+x Mn 2-x-y M y This may include, but is not limited to, heteroatom-substituted Li-Mn spinel with a composition represented by O4 (where M is one or more metallic elements selected from Al, Mg, Co, Fe, Ni, and Zn).

[0040] The positive electrode active material is not particularly limited, but may have a coating layer. The coating layer contains a material that has lithium ion conduction performance, low reactivity with the positive electrode active material and the solid electrolyte, and can maintain the form of the coating layer without flowing even when in contact with the active material and the solid electrolyte. Specific examples of the material constituting the coating layer include, in addition to LiNbO3, Li4Ti5O 12 , Li3PO4, etc., but are not limited thereto.

[0041] The shape of the positive electrode active material is not particularly limited as long as it is a general shape as the positive electrode active material of the battery. The positive electrode active material may be, for example, particulate. The positive electrode active material may be primary particles or secondary particles in which a plurality of primary particles are aggregated. The average particle diameter D 50 of the positive electrode active material may be, for example, 1 nm or more, 5 nm or more, or 10 nm or more, and may also be 500 μm or less, 100 μm or less, 50 μm or less, or 30 μm or less. The average particle diameter D 50 is the particle diameter (median diameter) at 50% of the integrated value in the volume-based particle size distribution determined by the laser diffraction / scattering method. (Negative electrode active material) As the negative electrode active material, various materials having a potential (charge / discharge potential) for occluding and releasing lithium ions that is lower than that of the positive electrode active material of the present disclosure can be adopted. The material of the negative electrode active material is not particularly limited and may be metallic lithium or a material capable of occluding and releasing metal ions such as lithium ions. Examples of the material capable of occluding and releasing metal ions such as lithium ions include, but are not limited to, alloy-based negative electrode active materials, carbon materials, or lithium titanate (Li4Ti5O 12 ), etc.

[0042] The alloy-based anode active material is not particularly limited and includes, for example, Si alloy-based anode active materials or Sn alloy-based anode active materials. Si alloy-based anode active materials include silicon, silicon oxide, silicon carbide, silicon nitride, or solid solutions thereof. Si alloy-based anode active materials may also contain metallic elements other than silicon, such as Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, In, Sn, Ti, etc. Sn alloy-based anode active materials include tin, tin oxide, tin nitride, or solid solutions thereof. Sn alloy-based anode active materials may also contain metallic elements other than tin, such as Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, In, Ti, Si, etc.

[0043] The carbon material is not particularly limited and examples include hard carbon, soft carbon, and graphite.

[0044] The shape of the negative electrode active material is not particularly limited, but any shape common for negative electrode active materials in batteries is acceptable. The negative electrode active material may be in the form of parts or sheets, for example.

[0045] (Binder) The material of the binder is not particularly limited. The binder may be, for example, polyvinylidene fluoride (PVdF), butadiene rubber (BR), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), etc., but is not limited to these. The binder is not particularly limited, and may be used alone or in combination of two or more types.

[0046] (solid electrolyte) The material of the solid electrolyte is not particularly limited and may be, for example, a sulfide solid electrolyte, an oxide solid electrolyte, or a polymer electrolyte.

[0047] Examples of sulfide solid electrolytes include, but are not limited to, sulfide-based amorphous solid electrolytes, sulfide-based crystalline solid electrolytes, or argyrodite-type solid electrolytes. Specific examples of sulfide solid electrolytes include the Li2S-P2S5 system (Li7P3S11 , Li3PS4, Li8P2S9, etc.), Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-LiBr-Li2S-P2S5, Li2S-P2S5-GeS2 (Li 13 GeP3S 16 Li 10 GeP2S 12 ), LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li 7-x PS 6-x Cl x Etc.; or combinations thereof, but not limited to these.

[0048] An example of an oxide solid electrolyte is Li7La3Zr2O 12 Li 7-x La3Zr 1-x Nb x O 12 Li 7-3x La3Zr2Al x O 12 Li 3x La 2 / 3-x TiO3, Li 1+x Al x Ti 2-x (PO4)3, Li 1+x Al x Ge 2-x (PO4)3, Li3PO4, or Li 3+x PO 4-x N x Examples include (LiPON), etc.; or combinations thereof, but are not limited to these.

[0049] The sulfide solid electrolyte and oxide solid electrolyte may be glass or crystallized glass (glass ceramics).

[0050] Examples of polymer electrolytes include, but are not limited to, polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof.

[0051] (Conductive additive) The conductive additive is not particularly limited. Examples of conductive additives include, but are not limited to, vapor-grown carbon fibers (VGCF), acetylene black (AB), Ketjenblack (KB), carbon nanotubes (CNT), and carbon nanofibers (CNF). The conductive additive may be particulate or fibrous, and its size is not particularly limited. While the conductive additive is not particularly limited, it may be used alone or in combination of two or more types.

[0052] Method for manufacturing electrode stacks The method for manufacturing the electrode laminate disclosed herein is: Laminating an electrode composite slurry layer on at least a portion of the first carbon coating layer, and The method includes irradiating the electrode mixture slurry layer, which is laminated on at least a portion of the first carbon coating layer, and the adjacent region with laser light to dry the electrode mixture slurry layer and form an electrode active material layer.

[0053] According to this disclosure, it is possible to provide a method for manufacturing an electrode laminate that is less prone to brittle fracture.

[0054] The electrode active material layer is generally formed by coating an electrode mixture slurry onto, for example, a current collector layer to form an electrode mixture slurry layer, and then drying the electrode mixture slurry layer.

[0055] When drying the electrode mixture slurry layer by irradiating it with a laser, the laser also irradiates adjacent areas. If the laser light absorption rate of the current collector layer surface in the adjacent area is low, the current collector layer in the adjacent area will not overheat, and heat transfer to the edge of the electrode mixture slurry layer will be suppressed. Therefore, the drying rate at the edge of the electrode mixture slurry layer will not increase, cracks will not occur in the formed electrode active material layer, and it will be possible to manufacture an electrode active material layer that is less prone to brittle fracture.

[0056] The method for manufacturing the electrode laminate according to this disclosure includes laminating the electrode mixture slurry layer onto at least a portion of the first carbon coat layer. The electrode laminate and the first carbon coat layer can be described by referring to the above-described description of the electrode laminate.

[0057] The electrode mixture slurry layer contains an electrode active material and a dispersion medium. For details regarding the electrode active material, refer to the description of the electrode active material layer above. The electrode mixture slurry layer may further optionally contain a binder, a solid electrolyte, and a conductive additive. For details regarding the binder, solid electrolyte, and conductive additive, refer to the description of the electrode active material layer above.

[0058] In this disclosure, “electrode mixture” means a composition that can constitute an electrode active material layer, either as is or by further containing other components. In this disclosure, “electrode mixture slurry” means a slurry that includes a dispersion medium in addition to the “electrode mixture,” and thereby can be applied and dried to form an electrode active material layer.

[0059] The dispersion medium is not particularly limited and may be nonpolar solvents such as heptane, xylene, and toluene, as well as polar solvents such as water, tertiary amine solvents, ether solvents, thiol solvents, ketone solvents (e.g., diisobutyl ketone) and ester solvents (e.g., butyl butyrate).

[0060] The content of the dispersion medium is not particularly limited, and may be such that the solid content of the electrode mixture slurry is 30% or more, 35% or more, 40% or more, 45% or more, or 50% or more, or it may be such that it is 80% or less, 75% or less, 70% or less, 65% or less, or 60% or less.

[0061] The method for laminating the electrode mixture slurry layer is not particularly limited and may include the doctor blade method, die coating method, gravure coating method, spray coating method, electrostatic coating method, bar coating method, etc.

[0062] The method for manufacturing the electrode laminate of this disclosure includes irradiating the electrode mixture slurry layer, which is laminated on at least a portion of the first carbon coat layer, and the adjacent region with laser light to dry the electrode mixture slurry layer and form an electrode active material layer. The adjacent region and the electrode active material layer can be described in the above-mentioned description of the electrode laminate.

[0063] The laser light source is not particularly limited and may be, for example, a Yb fiber laser, a YAG laser, a carbon dioxide laser, etc. The wavelength of the laser light may be 0.5 μm or more, 0.6 μm or more, 0.7 μm or more, 0.8 μm or more, or 0.9 μm or more, and may be 1.5 μm or less, 1.4 μm or less, 1.3 μm or less, 1.2 μm or less, or 1.1 μm or less.

[0064] The output of the laser light source is not particularly limited and may be appropriately determined by the laser light irradiation area, laser light irradiation time, etc. The output of the laser light source may be, for example, 0.01 J / s or more, 0.1 J / s or more, 1 J / s or more, 5 J / s or more, or 100 J or less, 50 J or less, or 10 J or less.

[0065] The irradiation time of the laser beam is not particularly limited, and may be extended, for example, until the reduction drying period of the electrode mixture slurry layer is reached. The irradiation time of the laser beam may be, for example, 30 seconds or more, 1 minute or more, or 2 minutes or more, and may be 30 minutes or less, 20 minutes or less, or 10 minutes or less.

[0066] The drying temperature is not particularly limited and may be 50°C or higher, 70°C or higher, 90°C or higher, 100°C or higher, 110°C or higher, or 120°C or higher, and may be 200°C or lower, 180°C or lower, 160°C or lower, 150°C or lower, or 140°C or lower. [Examples]

[0067] The present invention will be specifically described by examples and comparative examples, but the present invention is not limited thereto.

[0068] Fabrication of electrode active material layer Graphite as the electrode active material and styrene-butadiene copolymer (SBR) as the binder were weighed in seconds at a mass ratio of 97.9:2.1 and mixed with ion-exchanged water to prepare an electrode mixture slurry with a solid content of 55%.

[0069] As shown in Figure 3(a), a current collector layer was prepared for the fabrication of Example 1, in which a first carbon coating layer was laminated in a square shape with sides of 100 mm in the center of a square aluminum foil surface with sides of 200 mm, which served as a conductive layer.

[0070] As shown in Figure 3(b), a current collector layer for Example 2 was prepared, in which a first carbon coating layer with a width of 10 mm was laminated on the outer periphery of the current collector layer for Example 1.

[0071] As shown in Figure 3(c), a current collector layer for Example 2 was prepared, in which a first carbon coating layer with a width of 25 mm was laminated on the outer periphery of the current collector layer for Example 1.

[0072] As shown in Figure 3(d), a second carbon coat layer was formed by rubbing the first carbon coat layer, which is located in a square region with a side length of 100 mm in the central part of the surface of the current collector layer used to create Comparative Example 1, with a nonwoven fabric. This reduced the laser light absorption rate of the first carbon coat layer in the rubbed area, thus preparing the current collector layer for Example 4.

[0073] As shown in Figure 3(e), a current collector layer was prepared for creating Comparative Example 1, in which a first carbon coating layer was laminated over the entire surface of a square-shaped aluminum foil with a side length of 200 mm, which served as the conductive layer.

[0074] The absorption rate of the first carbon coating layer at a wavelength of 970 nm laser light was 0.5, the absorption rate of the second carbon coating layer at a wavelength of 970 nm laser light was 0.4, and the absorption rate of the conductive layer at a wavelength of 970 nm laser light was 0.05.

[0075] For the current collector layers used in Examples 1-4 and Comparative Example 1, the electrode mixture slurry was applied to the center of the surface in a square shape with sides of 100 mm and a thickness of 400 μm to form an electrode mixture slurry layer. Then, a 970 nm laser beam was irradiated for 60 seconds onto the 200 mm square area where the current collector was located and on the side where the electrode mixture slurry layer was laminated, to dry the electrode mixture slurry layer and produce the electrode laminates of Examples 1-4 and Comparative Example 1.

[0076] Here, Figure 4(a) corresponds to the electrode stack of Example 1, Figure 4(b) corresponds to the electrode stack of Example 2, Figure 4(c) corresponds to the electrode stack having an electrode active material layer of Example 3, Figure 4(d) corresponds to the electrode stack of Example 4, and Figure 4(e) corresponds to the electrode stack of Comparative Example 1.

[0077] Brittleness evaluation of electrode stacks The drying status of the electrode active material layer within 10 mm from the edge of the electrode laminates in Examples 1-4 and Comparative Example 1 was evaluated, as well as whether cracks were present by visual inspection. If cracks were present, the drying time from the start of drying of the electrode composite slurry until cracks appeared was measured. The drying time was defined as the time from the start of laser irradiation until the electrode composite slurry layer reached the reduction drying period.

[0078] The results of each evaluation are shown in Table 1.

[0079] [Table 1]

[0080] From Examples 1-3 and Comparative Example 1 in Table 1, it can be seen that when the conductive layer is exposed in the adjacent region due to the absence of the first carbon coating layer, the current collector layer in the adjacent region does not overheat, excessive heat transfer to the edge of the electrode mixture slurry layer is suppressed, and the formed electrode active material layer is less prone to cracking and has high toughness. Furthermore, from Example 4 and Comparative Example 1, it can be seen that by placing a second carbon coating layer with a lower laser light absorption rate than the first carbon coating layer in the adjacent region, cracking is less likely to occur, and heat transfer to the edge of the electrode mixture slurry layer is suppressed. [Explanation of Symbols]

[0081] 100 electrode stack 110 Current collector layer 111 Conductive layer 112 First carbon coating layer 113 Second carbon coating layer 120 Electrode active material layer 200 adjacent regions

Claims

1. An electrode laminate having a current collector layer and an electrode active material layer laminated on a part of the current collector layer, The current collector layer comprises a conductive layer and a first carbon coating layer laminated on at least a portion of the conductive layer. The electrode active material layer is laminated on at least a portion of the first carbon coating layer. In an adjacent region adjacent to the electrode active material layer, the current collector layer either does not have a first carbon coating layer, or has a second carbon coating layer having a lower absorption rate of 970 nm laser light than the first carbon coating layer. Electrode stack.

2. The electrode laminate according to claim 1, wherein the electrode active material layer is laminated only on a portion of the first carbon coating layer.

3. The electrode laminate according to claim 1, wherein the first carbon coating layer, which does not have the electrode active material layer laminated on it, is arranged on the periphery of the current collector layer.

4. The electrode laminate according to claim 1, wherein the absorption rate of the current collector layer with a wavelength of 970 nm laser light in the adjacent region is 40% or less.

5. Laminating an electrode composite slurry layer on at least a portion of the first carbon coating layer, and The electrode mixture slurry layer is laminated on at least a portion of the first carbon coating layer, and the adjacent region is irradiated with laser light to dry the electrode mixture slurry layer and form an electrode active material layer. A method for manufacturing an electrode laminate according to any one of claims 1 to 4, including the method described in any one of claims 1 to 4.

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