Method for manufacturing electrode and method for manufacturing battery

Abstract

To provide a method for manufacturing an electrode with a less wrinkled collector.SOLUTION: The method for manufacturing an electrode with a collector and a resin layer includes the step of welding the collector and the resin layer to each other while adjusting the heating temperature of a heating unit according to the overlapping part of the collector and the resin layer.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing an electrode and a method for manufacturing a battery. [Background technology]

[0002] Batteries equipped with electrodes in which wrinkles and distortion of the current collector are suppressed by disposing a reinforcing member made of resin on the surface of the current collector that is not coated with the active material are being considered.

[0003] Patent Document 1 discloses "a storage cell comprising: a positive electrode and a negative electrode having an active material layer on one surface of a current collector made of metal foil, the active material layers being arranged so as to face each other; a separator arranged between the positive electrode and the negative electrode and interposed between the active material layers; a spacer arranged between the positive electrode and the negative electrode and sealing between the edges of the current collector so as to surround the active material layer and form a storage space for storing an electrolyte; and a reinforcing member for reinforcing an uncoated portion of the current collector where the active material layer is not located, wherein the current collector has the uncoated portion between the spacer and the active material layer when viewed from a direction in which the active material layers of the positive electrode and the negative electrode face each other, and the reinforcing member is arranged along the uncoated portion so as to straddle a boundary between the active material layer and the uncoated portion and a boundary between the spacer and the uncoated portion when viewed from the facing direction." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-69042 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when assembling a battery, the resin expands or contracts due to heat when welding the current collector and the resin layer, which may cause wrinkles in the current collector. In particular, depending on the overlapping state between the current collector and the resin layer, the difference in the thermal expansion and contraction rates between the two may become significant, increasing the risk of wrinkles. Wrinkles in the current collector may lead to scratches or breakage of the current collector, which may reduce the sealing ability of the electrolyte in the battery, for example.

[0006] An object of one embodiment of the present disclosure is to provide a method for manufacturing an electrode having a current collector with reduced wrinkles. A problem to be solved by another embodiment of the present disclosure is to provide a method for manufacturing a battery including an electrode having a current collector with reduced wrinkles. [Means for solving the problem]

[0007] Means for solving the above problems include the following aspects. <1> A method for manufacturing an electrode having a current collector and a resin layer, comprising the steps of: a heating temperature of a heater being adjusted according to an overlapping area between the current collector and the resin layer, thereby fusing the current collector and the resin layer together. <2> When the overlapping area between the current collector and the resin layer is large, the heating temperature of the heater is reduced compared to when the overlapping area is small. <1> A method for producing the electrode according to claim 1. <3> The method further includes a step of checking an overlap between the current collector and the resin layer before welding the current collector and the resin layer. <1> or <2> A method for producing the electrode according to claim 1. <4> The method further includes a step of forming a positive electrode active material layer or a negative electrode active material layer on the current collector, <1> ~ <3> 13. A method for producing an electrode according to any one of the preceding claims. <5> <4> 2. A method for producing a battery, comprising: a step of producing an electrode by the electrode production method described in claim 1; a step of stacking the electrodes with a separator interposed therebetween to produce a laminate; and a step of sealing the laminate by welding a resin layer possessed by the electrodes. Effect of the Invention

[0008] According to one embodiment of the present disclosure, there is provided a method for manufacturing an electrode having a current collector with reduced wrinkles, and according to another embodiment of the present disclosure, there is provided a method for manufacturing a battery including an electrode having a current collector with reduced wrinkles. [Brief description of the drawings]

[0009] [Figure 1A] FIG. 1A is a schematic top view showing an example of an electrode structure according to the electrode manufacturing method of the present disclosure. [Figure 1B] FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A. [Diagram 2] FIG. 2 is a schematic top view showing an example of the welding step in the electrode manufacturing method of the present disclosure. [Diagram 3] FIG. 3 is a plot showing the relationship between the heating temperature of the heater or the welding temperature and the overlapping distance in the electrode manufacturing method of the present disclosure. [Figure 4] FIG. 4 is a schematic cross-sectional view showing an example of the structure of the battery of the present disclosure (the resin layer is not shown). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described. The description is for illustrating the embodiments and is not intended to limit the scope of the present disclosure.

[0011] In this specification, a numerical range indicated using "~" indicates a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in the present embodiment, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in the present embodiment. In addition, in the numerical ranges described in the present embodiment, the upper or lower limit of the numerical range may be replaced with a value shown in the examples.

[0012] In this specification, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.

[0013] In this specification, when an embodiment is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the size of the members in each drawing is conceptual, and the relative relationship between the sizes of the members is not limited to this.

[0014] In the present specification, each component may contain a plurality of corresponding substances. In the present embodiment, when the amount of each component in the composition is mentioned, in the case where a plurality of substances corresponding to each component are present in the composition, the amount means the total amount of the plurality of substances present in the composition, unless otherwise specified.

[0015] In this specification, the term "overlap width" refers to the so-called seal width (the portion where the current collector and the resin layer overlap) when the current collector and the resin layer are welded together.

[0016] <Electrode manufacturing method> The method for producing an electrode according to the present disclosure is a method for producing an electrode having a current collector and a resin layer, and includes a process for adjusting the heating temperature of a heater according to the overlapping area between the current collector and the resin layer, and fusing the current collector and the resin layer (hereinafter, also referred to as a "temperature-adjusted fusing process"). By including the above process, an electrode having a current collector with reduced wrinkles can be provided.

[0017] Here, Fig. 1A is a schematic top view showing an example of the structure of an electrode according to the manufacturing method of an electrode of the present disclosure. Fig. 1B is a cross-sectional view taken along line AA in Fig. 1A. In Figs. 1A and 1B, the electrode has a current collector 10 and a resin layer 20. The resin layer 20 is provided on the surface of the current collector 10 on which the active material is not coated. In addition, an active material layer 30 is provided on the current collector 10.

[0018] The manufacturing method of the electrode according to the present disclosure will be described in detail below.

[0019] -Current collector- The current collector preferably includes a positive electrode current collector and a negative electrode current collector, and may be a current collector in which a positive electrode current collector and a negative electrode current collector are bonded together.

[0020] The positive electrode current collector may be made of, for example, nickel, iron, stainless steel (SUS), titanium, or aluminum.

[0021] The positive electrode current collector may be in the form of, for example, a foil or a mesh.

[0022] Among them, the positive electrode current collector is preferably made of aluminum foil, which has excellent corrosion resistance and electrical conductivity. The aluminum foil may be surface-treated or carbon-coated.

[0023] The positive electrode current collector has a thickness of, for example, 8 μm to 10 μm.

[0024] The negative electrode current collector may be made of, for example, copper, stainless steel (SUS), or nickel.

[0025] The negative electrode current collector has a foil or mesh shape, for example.

[0026] Of these, the negative electrode current collector is preferably a copper foil from the viewpoint of excellent corrosion resistance and electrical conductivity.

[0027] The negative electrode current collector has a thickness of, for example, 10 μm to 20 μm.

[0028] -Resin layer- The resin layer is preferably a plate-like body containing a resin on the surface to be welded. When the battery is a laminated battery, the resin layer may be a part of the laminated exterior material. After the temperature-controlled welding step, the resin layer is provided on a part or the whole of the active material uncoated surface of the current collector.

[0029] The resin may be a polyolefin resin. Examples of the polyolefin resin include high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (L-LDPE), and polypropylene (PP). Among them, polypropylene (PP) is particularly preferred from the viewpoint of excellent weldability and electrolyte resistance. Polypropylene (PP) may be modified polypropylene.

[0030] The resin layer has a thickness of, for example, 40 μm to 100 μm.

[0031] (Temperature adjustment welding process) In the electrode manufacturing method of the present disclosure, when the current collector and the resin layer are welded together, the heating temperature of a heater is adjusted according to the overlapping area between the current collector and the resin layer. Description will be given with reference to Fig. 2. Fig. 2 is a schematic top view showing an example of the welding step in the manufacturing method of an electrode according to the present disclosure. 2, resin layer 20 is disposed on the surface of current collector 10 that is not coated with the active material, and heater H, an example of a temperature-adjustable heater, is disposed in a thermally connected state below current collector 10. The heating temperature of heater H is adjusted according to overlapping area W between current collector 10 and resin layer 20 to weld the current collector and the resin layer, thereby obtaining an electrode having a current collector with reduced wrinkles.

[0032] The heater refers to one including a heating element having a heat generating portion, and may be either a contact heater or a non-contact heater, and examples thereof include heaters such as electric heaters and radiant heaters.

[0033] Here, when heat is applied to the object, the degree of expansion is considered to be proportional to the thermal expansion coefficient, length (or area), and temperature rise of the object. Also, when the object is cooled, the degree of contraction is considered to be proportional to the contraction rate, length (or area), and temperature drop during the cooling and solidification process of the object. Since there is a difference in thermal expansion coefficient and contraction coefficient between the current collector and the resin layer, in order to suppress wrinkles in the current collector after the welding process, it is preferable to suppress the above-mentioned temperature rise and temperature drop and relieve the internal stress generated when welding the two. In this respect, in the manufacturing method of the electrode of the present disclosure, welding is performed by adjusting the heating temperature of the heater. That is, welding is performed while suppressing the temperature rise and temperature drop. As a result, an electrode having a current collector with suppressed wrinkles is obtained.

[0034] The temperature is adjusted according to the overlap. When the overlap is large, the contact area between the current collector and the resin layer increases, so that wrinkles caused by internal stress are more likely to occur. In this case, the heating temperature of the heater is lowered to suppress the thermal expansion and contraction of the portion to be welded, and the increase in the difference in thermal expansion and contraction between the resin and the current collector at the welded portion is suppressed. In other words, when the overlap is large, it is preferable to lower the heating temperature of the heater compared to when the overlap is small. On the other hand, when the overlap is small, the contact area between the current collector and the resin layer decreases, so that the internal stress decreases overall. In this case, the heating temperature of the heater can be increased to promote welding of the portion to be welded.

[0035] The temperature adjustment may be performed, for example, by lowering the heating temperature of the heater by 2°C from the predetermined temperature every time the overlap increases by 1 mm (see FIG. 3), by lowering the heating temperature of the heater by 1°C from the predetermined temperature every time the overlap increases by 1 mm, or by lowering the heating temperature of the heater by 0.5°C from the predetermined temperature every time the overlap increases by 1 mm. The temperature adjustment may be performed, for example, by raising the heating temperature of the heater by 2°C from the predetermined temperature every time the overlap decreases by 1 mm (see FIG. 3), by raising the heating temperature of the heater by 1°C from the predetermined temperature every time the overlap decreases by 1 mm, or by raising the heating temperature of the heater by 0.5°C from the predetermined temperature every time the overlap decreases by 1 mm. The temperature adjustment may be performed appropriately while observing the welding between the current collector and the resin layer.

[0036] The heating temperature of the heater can be set in a range equal to or higher than the softening point or melting point of the resin of the resin layer, and is preferably from the softening point or melting point to 200° C., and may be from 130° C. to 200° C., or may be from 130° C. to 150° C. For example, when the resin of the resin layer is polypropylene (PP), the heating temperature is preferably from 130° C. to 170° C., and more preferably from 140° C. to 160° C. By welding within the above range, welding strength can be high, and therefore an electrode having a current collector with reduced wrinkles can be easily obtained.

[0037] The welding pressure is not particularly limited as long as the current collector and the resin layer can be welded together while preventing wrinkles in the current collector. The welding pressure may be appropriately determined.

[0038] The welding method is not particularly limited as long as the current collector and the resin layer can be welded while suppressing wrinkles in the current collector. The current collector and the resin layer may be welded by heating them from above and / or below with a heater. In addition, from the viewpoint of sealing the electrodes, it is preferable to perform the welding under reduced pressure.

[0039] (Overlap check process) It is preferable that the method for manufacturing an electrode according to the present disclosure further includes a step of checking an overlap between the current collector and the resin layer before welding the current collector and the resin layer (hereinafter also referred to as an "overlap confirmation step").

[0040] The overlapping area may be checked visually or by using an image inspection device that displays a captured image. Using an image inspection device is more preferable from the viewpoint of process management because the overlapping area can be quantified. A commercially available flat sheet inspection device can be used as the image inspection device.

[0041] According to the method for manufacturing an electrode of the present disclosure described above, one embodiment of the present disclosure can provide a method for manufacturing an electrode having a current collector with reduced wrinkles.

[0042] The method for producing an electrode according to the present disclosure may include, in addition to the above-mentioned temperature-adjusted welding step and overlapping confirmation step, other steps for producing an electrode (for example, a series of steps including a kneading step, a coating step, a drying step, a pressing step, a slitting step, etc. (i.e., an active material layer forming step described below)). The method for producing an electrode according to the present disclosure preferably includes a step of forming a positive electrode active material layer or a negative electrode active material layer on a current collector (hereinafter also referred to as an "active material layer forming step").

[0043] In the kneading step, the positive electrode active material or the negative electrode active material, the conductive material, and the binder are kneaded to prepare a positive electrode or a negative electrode slurry. The kneading may be performed by a known method, for example, using a planetary mixer, a sand mill, a ball mill, a planetary mill, a roll mill, an extruder, or the like.

[0044] In the coating step, the slurry for forming the positive electrode active material layer or the negative electrode active material layer is preferably applied to the positive electrode current collector or the negative electrode current collector, respectively. The coating may be performed by a known method, for example, a slit die method or a doctor roll method.

[0045] In the drying step, the slurry applied to form the positive electrode active material layer or the negative electrode active material layer is dried at a temperature of 80°C to 135°C, for example.

[0046] In the pressing step, the dried positive electrode or negative electrode is pressed and rolled. The pressing is performed by, for example, a roll press, a cold isostatic press (CIP), or the like. The pressing pressure is, for example, 1.0 t / cm. 2 ~3.0t / cm 2 It is.

[0047] In the slitting step, the rolled positive electrode or negative electrode is cut into a predetermined size. The slitting can be performed according to a known method.

[0048] <Battery manufacturing method> The method for manufacturing a battery according to the present disclosure includes at least a step of manufacturing an electrode by the above-described method for manufacturing an electrode according to the present disclosure (hereinafter also referred to as an "electrode manufacturing step"), a step of stacking the electrodes with a separator interposed therebetween to manufacture a laminate (hereinafter also referred to as a "laminate manufacturing step"), and a step of sealing the laminate by welding a resin layer possessed by the electrode (hereinafter also referred to as a "sealing step"), and may include a connecting step, a laminating step, etc. as necessary.

[0049] In the lamination step, the electrodes are alternately laminated with a solid electrolyte layer or a separator interposed therebetween to produce a laminate. The lamination can be performed, for example, by using a known lamination device.

[0050] In the sealing step, the laminate is sealed by welding the resin layers of the electrodes. The welding can be performed using an ultrasonic welding device or the like.

[0051] When the method includes a connecting step, the side members (terminals, etc.) are connected to the current collectors (positive electrode current collector and / or negative electrode current collector). The connection of the terminals, etc. can be performed using, for example, an ultrasonic welding device.

[0052] When a lamination step is included, an electrode body including the electrode and active material layer of the present disclosure can be covered with a laminate exterior material and heat-sealed to form a laminate body. When the battery including the electrode of the present disclosure is, for example, a laminate type battery, the battery can be manufactured through a lamination process in which a laminate exterior material is used for lamination.

[0053] <Battery> In the present disclosure, the battery preferably includes an electrode having a current collector and a resin layer, a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer or a separator. If the battery is not an all-solid-state battery, the battery preferably includes a separator and contains a liquid electrolyte.

[0054] Fig. 4 is a schematic cross-sectional view showing an example of the structure of a battery (a resin layer is not shown). In Fig. 4, the battery has a negative electrode current collector 113, a negative electrode active material layer A, a solid electrolyte layer B or a separator B, a positive electrode active material layer C, and a positive electrode current collector 115. The negative electrode active material layer A contains a negative electrode active material 101, a conductive material 105, and a binder 109. The positive electrode active material layer C contains a positive electrode active material 103, a conductive material 107, and a binder 111. The solid electrolyte layer B or the separator B may have a single-layer structure or a multi-layer structure.

[0055] -Cathode active material layer- The positive electrode active material layer preferably contains a positive electrode active material. The positive electrode active material may be, for example, a lithium composite oxide. The lithium composite oxide may contain at least one element selected from the group consisting of F, Cl, N, S, Br and I. The shape of the positive electrode active material is not particularly limited, and may be, for example, spherical (e.g., perfect sphere, oval sphere, etc.), fibrous, etc. When the positive electrode active material is spherical, the particle size is, for example, 0.1 μm to 30 μm. The specific surface area of ​​the positive electrode active material is, for example, 0.1 m 2 / g~100m 2 / g.

[0056] -Negative electrode active material layer- The negative electrode active material layer preferably contains a negative electrode active material. Examples of the negative electrode active material include Li-based active materials such as metallic lithium, carbon-based active materials such as graphite, and lithium titanate (e.g., Li 4 Ti 5 O 12 and Si-based active materials such as simple silicon. The shape of the negative electrode active material is not particularly limited, and may be, for example, spherical (e.g., perfect sphere, oval sphere, etc.), fibrous, etc. When the negative electrode active material is spherical, the particle size is, for example, 0.1 μm to 30 μm. The specific surface area of ​​the negative electrode active material is, for example, 0.1 m 2 / g~1500m 2 / g.

[0057] The positive electrode active material layer and the negative electrode active material layer preferably contain a conductive material and a binder. By containing the conductive material, the conductivity between the active materials and between the active materials and the current collector can be improved. In addition, by containing the binder, the active materials can be bonded to each other and between the active materials and the current collector.

[0058] Examples of conductive materials include acetylene black, ketjen black, vapor grown carbon fiber (VGCF (registered trademark)), and carbon nanotubes. The content of the conductive material is, for example, 3% by mass to 5% by mass with respect to the active material.

[0059] Examples of the binder include polyvinylidene fluoride (PVDF) / NMP-based and styrene-butadiene rubber (SBR) / water-based binders. The content of the binder is, for example, 3% by mass to 5% by mass with respect to the active material.

[0060] -Solid electrolyte layer- When the battery of the present disclosure is a solid-state battery (e.g., an all-solid-state battery), the battery preferably has a solid electrolyte layer.

[0061] The solid electrolyte may be, for example, at least one solid electrolyte selected from the group of solid electrolytes consisting of sulfide solid electrolytes, oxide solid electrolytes, and halide solid electrolytes. The shape of the solid electrolyte is not particularly limited and may be, for example, spherical (for example, perfect sphere, oval sphere, etc.), fibrous, etc. When the solid electrolyte is spherical, the particle size is, for example, 0.01 μm to 1 μm. The specific surface area of ​​the solid electrolyte is, for example, 25 m 2 / g~30m 2 / g.

[0062] -Separator- When the battery of the present disclosure contains a liquid electrolyte (electrolytic solution), the battery preferably contains a separator, such as a resin sheet of polyethylene (PE) or polypropylene (PP).

[0063] -Liquid electrolyte- The liquid electrolyte is, for example, LiPF with a concentration of 0.1 mol / L to 1 mol / L. 6 , LiBF 4 , LiAsF 6 and carbonate-based solvents such as ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC), which contain salts of the above. [Explanation of symbols]

[0064] 10 Current collector 20 Resin layer 30 Active material layer 101 Negative electrode active material 103 Cathode active material 105, 107 Conductive materials 109, 111 Binder 113 Negative electrode current collector 115 Positive electrode current collector A negative electrode active material layer B Solid electrolyte layer or separator C positive electrode active material layer H heater W overlap (seal width)

Claims

1. A method for manufacturing an electrode having a current collector and a resin layer, comprising the steps of: a heating temperature of a heater being adjusted according to an overlapping area between the current collector and the resin layer, thereby fusing the current collector and the resin layer together.

2. The method for manufacturing an electrode according to claim 1 , wherein when the overlapping area between the current collector and the resin layer is large, the heating temperature of the heater is lowered compared to when the overlapping area is small.

3. The method for producing an electrode according to claim 1 or 2, further comprising the step of checking an overlapping margin between the current collector and the resin layer before welding the current collector and the resin layer together.

4. The method for producing an electrode according to claim 1 or 2, further comprising the step of forming a positive electrode active material layer or a negative electrode active material layer on the current collector.

5. A step of producing an electrode by the method of producing an electrode according to claim 4; a step of stacking the electrodes with a separator therebetween to produce a laminate; a step of sealing the laminate by welding the resin layer of the electrode; A method for manufacturing a battery comprising at least the steps of:

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