Manufacturing method of electrode plate

Abstract

To suppress a curved surface part from being formed on an outer peripheral edge part of an electrode tab of a manufactured electrode plate.SOLUTION: A manufacturing method of an electrode plate disclosed herein includes: a preparation step of preparing a strip-shaped electrode plate material 20A before tab cutting; and a tab cutting step of, while conveying the electrode plate material 20A in a long-side direction L, irradiating the electrode plate material 20A during conveyance with a pulse laser to manufacture an electrode plate having a plurality of electrode tabs at an end part in a short-side direction S of the electrode plate material 20A. In the tab cutting step, an average output of the pulse laser per unit time is controlled to 300 W to 1000 W. Accordingly, when irradiated with such a high-power pulse laser, an electrode core body 22 immediately evaporates, and thus it is possible to suppress the formation of a curved surface part which is a trace of melt cutting of the electrode core body 22.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The technology disclosed herein relates to a method for manufacturing an electrode plate. [Background technology]

[0002] An energy storage device such as a lithium-ion secondary battery includes, for example, an electrode assembly in which a positive electrode plate and a negative electrode plate face each other via a separator. Hereinafter, these positive and negative electrode plates are collectively referred to as "electrode plates." The electrode plate includes, for example, an electrode core, which is a foil-shaped metal member, and an electrode active material layer containing an electrode active material applied to the surface of the electrode core. To manufacture an electrode plate with such a configuration, first, an electrode active material layer is applied to the surface of a large electrode core. This results in a strip-shaped electrode plate material. A core-exposed region, where the electrode core is exposed without the electrode active material layer applied, is formed at the short-side end of the electrode plate material. An electrode tab is formed by cutting out the region including the core-exposed region with a laser or the like. An example of a technique for forming such an electrode tab is disclosed in JP 2016-33912 A. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-33912 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the transport speed of electrode plates has increased in the manufacture of electricity storage devices to improve productivity. Such high-speed manufacturing can result in damage to electrode tabs on the electrode plates, reducing the yield of electricity storage device manufacturing. The technology disclosed herein has been developed to solve this problem, and aims to provide a manufacturing method that can prevent damage to electrode tabs during transport. [Means for solving the problem]

[0005] To address the above-mentioned problems, there is provided a method for manufacturing an electrode plate (hereinafter also simply referred to as "manufacturing method") having the following configuration.

[0006] The method for manufacturing an electrode plate disclosed herein includes a preparation step of preparing a strip-shaped electrode plate material before tab cutting, and a tab cutting step of irradiating the electrode plate material with a pulsed laser while transporting the electrode plate material in the longitudinal direction to produce an electrode plate having multiple electrode tabs at the ends of the electrode plate material in the lateral direction. In this tab cutting step, the average output of the pulsed laser per unit time is controlled to 300 W to 1000 W.

[0007] According to the inventors' investigations, in the manufacturing method described in JP 2016-33912 A, a CW laser (continuous wave laser) is used to cut the electrode plate material. This CW laser cuts the electrode core while melting it. As a result, a portion (curved surface portion) where the molten metal has solidified is formed at the end of the manufactured electrode tab. The above document states that the curved surface portion has the function of preventing damage to the separation membrane (separator). However, in high-speed manufacturing of electrode plates, the electrode plate flutters during transportation. This may cause the curved surface portion to peel off from the end of the electrode tab, resulting in the electrode tab being torn.

[0008] In contrast, in the manufacturing method configured as described above, the average output of the pulse laser in the tab cutting process is controlled to 300 W or more. When such a high-output pulse laser is irradiated, the electrode core instantly evaporates. This prevents large amounts of heat from being transferred to the periphery of the laser irradiation position. As a result, the formation of a curved surface portion, which is a portion where molten metal has solidified, on the electrode tab after cutting can be suppressed. However, if the average output of the pulse laser is set too high, excessive heat is applied to the electrode core in the very short time before cutting. In this case, too, a curved surface portion is likely to be formed. For this reason, in the manufacturing method disclosed herein, the average output of the pulse laser is controlled to 1000 W or less. As described above, the manufacturing method disclosed herein can suppress the formation of a curved surface portion on the electrode tab of the manufactured electrode plate. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a plan view schematically showing an example of an electrode plate after manufacture. [Figure 2] FIG. 2 is a flowchart showing a method for manufacturing an electrode plate according to one embodiment. [Figure 3] FIG. 3 is a plan view illustrating a method for manufacturing an electrode plate according to one embodiment. [Figure 4] FIG. 4 is a cross-sectional view taken along the line VI-VI in FIG. [Figure 5] FIG. 5 is a cross-sectional SEM photograph (1000x magnification) of the negative electrode tab of the negative electrode plate. [Figure 6] FIG. 6 is a microscope photograph of the edge of the main body of the negative electrode plate. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the technology disclosed herein will be described with reference to the drawings. It should be noted that matters other than those specifically mentioned in this specification that are necessary for implementing the technology disclosed herein (for example, the general configuration and manufacturing process of an electricity storage device) can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the relevant field. In this specification, the expression "A to B" indicating a range means not less than A and not more than B, and also includes the meanings "preferably greater than A" and "preferably smaller than B."

[0011] In this specification, the term "electricity storage device" refers to a concept that encompasses devices in which charge and discharge reactions occur due to the movement of charge carriers between a pair of electrode plates (a positive electrode plate and a negative electrode plate). That is, the electricity storage device in the technology disclosed herein encompasses secondary batteries such as lithium ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries, as well as capacitors such as lithium ion capacitors and electric double layer capacitors.

[0012] 1. Description of the object of manufacture Below, an overview of the electrode plate to be manufactured will be explained, followed by a description of the method for manufacturing an electrode plate according to this embodiment. Fig. 1 is a plan view schematically showing an example of an electrode plate after manufacture. The manufacturing method according to this embodiment is directed to manufacturing a negative electrode plate 20 shown in Fig. 1.

[0013] As shown in FIG. 1, the negative electrode plate 20 is a long, strip-shaped member. The negative electrode plate 20 includes a negative electrode core 22, which is a foil-shaped metal member, and a negative electrode active material layer 24 provided on the surface of the negative electrode core 22. From the viewpoint of battery performance, the negative electrode active material layer 24 is preferably provided on both sides of the negative electrode core 22. In a plan view, the negative electrode plate 20 includes an electrode plate main body 20b and a negative electrode tab 22t. The electrode plate main body 20b is a region where the negative electrode active material layer 24 is provided on the surface of the negative electrode core 22. On the other hand, the negative electrode tab 22t is a region where the negative electrode active material layer 24 is not provided and where the negative electrode core 22 is exposed. The negative electrode tab 22t protrudes outward in the short-side direction S (upward in FIG. 1) from a part of an edge 20b1 of the electrode plate main body 20b in the short-side direction S. The negative electrode plate 20 also has a plurality of negative electrode tabs 22t. These plurality of negative electrode tabs 22t are provided in the longitudinal direction L of the negative electrode plate 20 at predetermined intervals.

[0014] Materials that can be used in conventional general electricity storage devices can be used without particular restrictions for each member constituting the negative electrode plate 20. For example, a metal material with a predetermined conductivity can be preferably used for the negative electrode substrate 22. The negative electrode substrate 22 is preferably made of, for example, copper or a copper alloy. The thickness of the negative electrode substrate 22 is preferably 2 μm to 30 μm, more preferably 3 μm to 20 μm, and even more preferably 5 μm to 15 μm.

[0015] The negative electrode active material layer 24 is a layer containing an electrode active material for a negative electrode (negative electrode active material). The negative electrode active material is a material capable of reversibly absorbing and releasing charge carriers in relation to the positive electrode active material. Examples of such negative electrode active materials include carbon materials and silicon-based materials. Examples of carbon materials that can be used include graphite, hard carbon, soft carbon, and amorphous carbon. Amorphous carbon-coated graphite, in which the surface of graphite is coated with amorphous carbon, can also be used. Examples of silicon-based materials include silicon and silicon oxide (silica). Silicon-based materials may also contain other metal elements (e.g., alkaline earth metals) or their oxides. The negative electrode active material layer 24 may also contain additives other than the negative electrode active material. Examples of such additives include binders and thickeners. Specific examples of binders include rubber-based binders such as styrene butadiene rubber (SBR). Specific examples of thickeners include carboxymethyl cellulose (CMC). The content of the negative electrode active material is generally 30% by mass or more, and typically 50% by mass or more, when the total solid content of the negative electrode active material layer 24 is taken as 100% by mass. The negative electrode active material may account for 80% by mass or more, or may account for 90% by mass or more, of the negative electrode active material layer 24. The thickness of the negative electrode active material layer 24 is preferably 10 μm to 500 μm, more preferably 30 μm to 400 μm, and even more preferably 50 μm to 300 μm.

[0016] 2. Electrode plate manufacturing method Next, a method for manufacturing the negative electrode plate 20 having the above configuration will be described. FIG. 2 is a flowchart showing a method for manufacturing an electrode plate according to this embodiment. FIG. 3 is a plan view illustrating the method for manufacturing an electrode plate according to this embodiment. As shown in FIG. 2, the manufacturing method according to this embodiment includes a preparation step S10 and a tab cutting step S20. Each step will be described below.

[0017] (1) Preparation process S10 In this step, a strip-shaped electrode plate material is prepared before tab cutting. In this specification, the term "electrode plate material" refers to an electrode plate before electrode tabs are formed. As shown in FIG. 3, when manufacturing a negative electrode plate 20, an electrode plate material for the negative electrode plate 20 (hereinafter referred to as "negative electrode plate material 20A") is prepared. This negative electrode plate material 20A includes a strip-shaped negative electrode core 22 that is a metal foil. The area of ​​the negative electrode core 22 of this negative electrode plate material 20A is larger than the area of ​​the manufactured negative electrode plate 20 (see FIG. 2). A negative electrode active material layer 24 is applied to the surface of the negative electrode core 22. The negative electrode active material layer 24 is applied to the central portion of the negative electrode core 22 in the short-side direction S. The negative electrode active material layer 24 extends along the long-side direction L. In this specification, the region where the negative electrode active material layer 24 is applied is referred to as the "negative electrode active material applied region A1." On the other hand, at both ends of the negative electrode plate material 20A in the short-side direction S (regions outside the short-side direction S of the negative electrode active material layer 24), the negative electrode active material layer 24 is not provided, and the negative electrode core 22 is exposed. In this specification, the region where the negative electrode core 22 is exposed is referred to as the "negative electrode core exposed region A2." The means for preparing the negative electrode plate material 20A having the above configuration is not particularly limited, and various conventionally known methods can be used without particular limitation. For example, the negative electrode plate material 20A can be prepared by applying a raw material paste containing a negative electrode active material and the like to the surface of the negative electrode core 22 and then drying it. Furthermore, the preparation step S10 is not particularly limited as long as the negative electrode plate material 20A can be prepared. For example, a separately prepared negative electrode plate material 20A may be purchased and prepared. Note that the negative electrode plate material is not limited to the structure shown in FIG. 3 . For example, the negative electrode plate material may have a structure in which a negative electrode core exposed region is formed only at one end in the short-side direction.

[0018] (2) Tab cutting process S20 In this step, the electrode plate material (negative electrode plate material 20A) is conveyed in the longitudinal direction L, and the electrode plate material (negative electrode plate material 20A) being conveyed is irradiated with a pulsed laser. As a result, an electrode plate (negative electrode plate 20) having a plurality of electrode tabs (negative electrode tabs 22t) at the end of the electrode plate material (negative electrode plate material 20A) in the lateral direction S can be produced, as shown in FIG. 2. The tab cutting step S20 in this embodiment will be described in detail below.

[0019] (a) Cutting of the active material application region Dotted line L in Figure 3 N1 As shown in Fig. 3, in the tab cutting process S20, first, the negative electrode active material application region A1 of the negative electrode plate material 20A is cut with a pulse laser along the longitudinal direction L. In this laser cutting, the irradiation position of the pulse laser in the transverse direction S is fixed to the negative electrode active material application region A1. Then, in the tab cutting process S20, the negative electrode plate material 20A is transported in a first direction L1 (leftward in Fig. 3) along the longitudinal direction L of the negative electrode plate material 20A. Then, the irradiation position of the pulse laser is controlled so that the pulse laser moves relatively in a second direction L2, which is the opposite direction to the first direction L1. As a result, the dotted line L N1 The negative electrode active material application region A1 is cut along the line.

[0020] In controlling the irradiation position of the pulse laser, the direction in which the pulse laser is actually moved is not particularly limited. For example, if the pulse laser is moved in the second direction L2 relative to the negative electrode plate material 20A being transported in the first direction L1, the cutting speed (processing speed) is significantly improved. On the other hand, if the movement of the pulse laser in the longitudinal direction L is stopped, the laser cutting speed and the transport speed of the negative electrode plate material 20A become the same. Also, the pulse laser may be moved in the first direction L1 as long as it is slower than the transport speed of the negative electrode plate material 20A. Even in this case, since the pulse laser moves in the second direction L2 relative to the negative electrode plate material 20A, the dotted line L N1 The negative electrode plate material 20A can be cut along the

[0021] In addition, the above dotted line L N1As shown in Fig. 1, when the negative electrode active material-applied region A1 is cut with a laser, a portion of the negative electrode substrate 22 melted by the heat of the laser may be mixed into the negative electrode active material layer 24. If the molten metal solidifies within the negative electrode active material layer 24, the flexibility of the negative electrode active material layer 24 is significantly reduced, potentially resulting in fragments of the negative electrode active material layer 24 easily falling off or peeling off with a slight impact. In the active material-applied region cutting step S2 of this embodiment, a pulsed laser is used to cut the negative electrode active material-applied region A1 to prevent a decrease in flexibility due to the inclusion of the molten metal. A pulsed laser can apply a large amount of concentrated energy in a short time span (high peak output), allowing the negative electrode substrate 22 to be quickly cut with a small amount of melting. This prevents a decrease in flexibility of the negative electrode active material layer 24 due to the inclusion of the molten metal, thereby preventing fragments of the negative electrode active material layer 24 from falling off or peeling off.

[0022] (b) Migration to the core-exposed area Next, the dotted line L in Figure 3 N2 As shown in Fig. 1, the pulsed laser is moved from the negative electrode active material application region A1 toward the negative electrode substrate exposed region A2. Specifically, by moving the pulsed laser toward the outside in the short-side direction S, the laser irradiation position can be moved to the negative electrode substrate exposed region A2. In this process, in addition to the outward movement in the short-side direction S, it is preferable to move the pulsed laser in a first direction L1 so as to follow the negative electrode plate material 20A being transported. This reduces the relative laser movement speed in the longitudinal direction L.

[0023] (c) Cutting the exposed core area Next, the dotted line L in Figure 3 N3 As shown in Fig. 1, in this process, the negative electrode substrate exposed region A2 of the negative electrode plate material 20A is cut with a pulsed laser along the longitudinal direction L. Specifically, after the pulsed laser reaches the negative electrode substrate exposed region A2, the irradiation position of the pulsed laser in the short direction S is fixed. Then, the irradiation position of the pulsed laser is controlled so that the pulsed laser moves in the second direction L2 relative to the negative electrode plate material 20A being transported in the first direction L1. As a result, the negative electrode plate material 20A is cut along the dotted line L N3The negative electrode substrate exposed region A2 can be cut along the line . As in the above "(a) Cutting of the active material applied region", the actual movement direction of the pulsed laser is not particularly limited.

[0024] (d) Movement to the active material application area Next, the dotted line L in Figure 3 N4 As shown in Fig. 1, in this step, the pulsed laser is moved from the negative electrode substrate exposed region A2 toward the negative electrode active material applied region A1. Specifically, by moving the pulsed laser toward the inside in the short side direction S, the laser irradiation position can be moved to the negative electrode active material applied region A1. Note that, similar to the above "(b) Movement to the substrate exposed region," in this step, in addition to the movement in the short side direction S, it is preferable to move the pulsed laser in the first direction L1 so as to follow the negative electrode plate material 20A being transported.

[0025] In the manufacturing method according to this embodiment, after the pulsed laser reaches the negative electrode active material applied region A1, the irradiation position of the pulsed laser in the short-side direction S is fixed. This allows the above-mentioned "(a) Cutting of the active material applied region" to be performed again, and the negative electrode active material applied region A1 of the negative electrode plate material 20A to be cut along the longitudinal direction L (dotted line L N1 In this way, in the tab cutting step S20 of this embodiment, the dotted line L N1 The pulse laser is repeatedly moved along LN4, thereby forming a plurality of negative electrode tabs 22t at the end of the negative electrode plate material 20A in the short-side direction S.

[0026] In the tab cutting process S20 of this embodiment, the average output of the pulse laser per unit time is controlled to 300 W to 1000 W. This can prevent the formation of a curved surface on the negative electrode tab 22t after cutting. Specifically, when a pulse laser with an average output of 300 W or more is used, the negative electrode substrate 22 immediately evaporates during the above-described tab cutting. This can prevent large amounts of heat from being transferred to the periphery of the laser irradiation position. As a result, the amount of melting of the negative electrode substrate 22 at the laser irradiation position can be reduced, thereby preventing the formation of a curved surface due to solidification of the molten metal. Note that as the average output of the pulse laser increases, the above-described melting suppression effect improves. From this perspective, the lower limit of the average output of the pulse laser may be 350 W or more, 400 W or more, 450 W or more, 500 W or more, 550 W or more, or 600 W or more. On the other hand, if the average output of the pulsed laser becomes too high, there is a risk that excessive heat will be applied to the negative electrode substrate 22 in the short time before cutting. In this case, it is more likely that a curved surface portion will be formed. For this reason, in this embodiment, the upper limit of the average output of the pulsed laser is controlled to 1000 W or less. Furthermore, as the average output of the pulsed laser decreases, it becomes more difficult for excessive heat to be applied to the negative electrode substrate 22. From this perspective, the lower limit of the average output of the pulsed laser may be 950 W or less, 900 W or less, 850 W or less, 800 W or less, 750 W or less, or 700 W.

[0027] The conveying speed of the negative electrode plate material 20A is preferably 30 m / min or more, more preferably 35 m / min or more, even more preferably 40 m / min or more, and particularly preferably 45 m / min or more. This improves the production efficiency of the negative electrode plate 20. On the other hand, as the conveying speed increases, the negative electrode tab is more likely to be damaged due to peeling of the curved surface. However, the technology disclosed herein can suppress the formation of a curved surface on the negative electrode tab 22t, thereby achieving stable high-speed conveying. On the other hand, if the conveying speed of the negative electrode plate material 20A becomes too fast, it becomes difficult to move the pulse laser in accordance with the conveying speed. From this perspective, the conveying speed of the negative electrode plate material 20A is preferably 80 m / min or less, more preferably 75 m / min or less, even more preferably 70 m / min or less, and particularly preferably 65 m / min or less.

[0028] The laser processing speed in the tab cutting process S20 may be 26 m / min or more, 28 m / min or more, 30 m / min or more, or 32 m / min or more. In this specification, the term "laser processing speed" refers to the average relative movement speed of the pulse laser with respect to the electrode plate material being transported. As described above, moving the pulse laser in the direction of transport of the electrode plate material decreases the laser processing speed. Moving the pulse laser in the opposite direction to the direction of transport of the electrode plate material increases the laser processing speed. Increasing this laser processing speed prevents laser heat from concentrating at specific locations, thereby more effectively suppressing the formation of curved surfaces. Therefore, from the perspective of more effectively suppressing the formation of curved surfaces, the laser processing speed is preferably 34 m / min or more, and particularly preferably 36 m / min or more.

[0029] Furthermore, when the conveying speed of the negative electrode plate material 20A is 100%, the laser processing speed (relative moving speed of the laser) is preferably 115% or more, more preferably 120% or more, and particularly preferably 125% or more. This can more effectively suppress the formation of curved surfaces. On the other hand, from the viewpoint of preventing cutting defects, the ratio of the laser processing speed to the conveying speed is preferably 140% or less, more preferably 135% or less, and particularly preferably 130% or less. Note that when controlling the laser processing speed, it is preferable to adjust the moving speed of the pulse laser while keeping the conveying speed of the negative electrode plate material 20A constant. This is because changing the conveying speed of the negative electrode plate material 20A makes it difficult to control other manufacturing equipment. For example, when the laser processing speed is 128% of the conveying speed, it is recommended to move the pulse laser in the opposite direction (second direction) to the conveying direction at a speed of 28% of the conveying speed. Furthermore, when the pulse laser is moved in the transport direction (first direction), the pulse laser may be moved at a speed that is 228% of the transport speed.

[0030] Furthermore, the pulse width of the pulse laser is preferably 30 ns or more, more preferably 35 ns or more, even more preferably 40 ns or more, and particularly preferably 45 ns or more. This prevents poor cutting due to insufficient energy. On the other hand, if the pulse width of the pulse laser is too long, excessive energy is applied to the area around the laser irradiation position, increasing the possibility of forming a curved surface after cutting. From this perspective, the pulse width of the pulse laser is preferably 120 ns or less, more preferably 110 ns or less, even more preferably 100 ns or less, and particularly preferably 90 ns or less.

[0031] Furthermore, the repetition frequency of the pulsed laser is preferably 2250 kHz or less, more preferably 2200 kHz or less, even more preferably 2150 kHz or less, and particularly preferably 2100 kHz or less. This can prevent the formation of curved surfaces due to excess energy. On the other hand, the repetition frequency of the pulsed laser is preferably 450 kHz or more, more preferably 500 kHz or more, even more preferably 550 kHz or more, and particularly preferably 600 kHz or more. This can prevent poor cutting due to insufficient energy.

[0032] The overlap ratio of the pulsed laser is preferably 99% or less, more preferably 98.8% or less, even more preferably 98.4% or less, and particularly preferably 98.2% or less. As the overlap ratio decreases, the area of ​​the laser irradiated overlappingly at the same position on the electrode plate material decreases, making it difficult to form a curved surface on the negative electrode tab 22t after cutting. The overlap ratio of the pulsed laser is preferably 95% or more, more preferably 96% or more, even more preferably 97% or more, and particularly preferably 97.5% or more. This can prevent cutting defects. Note that the "overlap ratio" in this specification refers to the degree to which two adjacent spots overlap when irradiated with a pulsed laser. Note that the spot diameter of the pulsed laser is preferably 10 μm to 60 μm, more preferably 20 μm to 50 μm, and even more preferably 25 μm to 40 μm. This allows the negative electrode plate 20 to be easily cut out from the negative electrode plate material 20A.

[0033] (Other processes) As described above, the tab cutting step S20 in this embodiment is the cutting of the active material-applied region (dotted line L in FIG. 3). N1 ) ~ Movement to the active material application region (dotted line L in Figure 3) N4 ) are repeated to form a plurality of negative electrode tabs 22t. N5As shown in FIG. 1, the center of the negative electrode plate material 20A in the short-side direction S is cut along the longitudinal direction L. This makes it possible to produce a negative electrode plate 20 (see FIG. 2) in which a negative electrode tab 22t is formed on only one side of the edge portion 20b1 of the electrode plate main body portion 20b. N6 As shown in the figure, the negative electrode plate material 20A is cut in the short direction S at predetermined intervals in the longitudinal direction L. This allows the negative electrode plate 20 to be manufactured in a desired length. N5 , L N6 The cutting of the negative electrode plate material 20A along the two-dot chain line L does not necessarily require laser cutting, and a cutting blade, a mold, a cutter, or the like may be used. N5 , L N6 When laser cutting is used for cutting along these two-dot chain lines L, it is preferable to use a pulsed laser, as in the tab cutting step S20. This makes it possible to more suitably prevent the fragments of the negative electrode active material layer 24 from peeling off or falling off. N5 , L N6 The cutting along the line may be carried out as appropriate depending on the shape of the negative electrode plate after manufacture, and does not limit the technology disclosed herein.

[0034] As described above, in the manufacturing method according to this embodiment, the average output of the pulse laser in the tab cutting process S20 is controlled to 300 W to 1000 W. This prevents the negative electrode substrate 22 from melting due to the heat of the laser. As a result, as shown in FIG. 4, the formation of a curved portion (in other words, a cut mark having a substantially spherical cross-sectional shape) due to solidification of molten metal can be suppressed at the side edge portion 22t1 of the negative electrode tab 22t of the manufactured negative electrode plate 20. The effectiveness of this manufacturing method has been confirmed by experiments. FIG. 5 is a cross-sectional SEM photograph of a negative electrode tab cut using the technology disclosed herein. As shown in this cross-sectional SEM photograph, the manufacturing method according to this embodiment can suppress the formation of a curved portion at the side edge portion of the negative electrode tab after cutting. FIG. 6 is a microscope photograph of the edge portion of the electrode plate main body portion cut using the technology disclosed herein. As shown in this photograph, the manufacturing method according to this embodiment can also suppress the formation of a curved portion at the edge portion of the electrode plate main body portion.

[0035] <Other embodiments> The above describes one embodiment of the technology disclosed herein. Note that the above embodiment shows an example to which the technology disclosed herein is applied, and does not limit the technology disclosed herein.

[0036] For example, in the above-described embodiment, a negative electrode plate is manufactured as the electrode plate. However, the manufacturing target of the electrode plate manufacturing method disclosed herein is not limited to a negative electrode plate, and may also be a positive electrode plate. Even when such a positive electrode plate is manufactured, the formation of a curved surface portion on the electrode tab (positive electrode tab) of the manufactured electrode plate (positive electrode plate) can be prevented. As described above, the electrode core (negative electrode core) of the negative electrode plate is made of copper or a copper alloy. These copper-based electrode cores have a high melting point, so the formation of a curved surface portion due to melt cutting is likely to occur. In contrast, according to the manufacturing method disclosed herein, even in the manufacture of a negative electrode plate using a copper-based electrode core, the electrode core can be instantly evaporated, thereby suppressing the formation of a curved surface portion. Therefore, the electrode plate manufacturing method disclosed herein is particularly suitable for the manufacture of negative electrode plates.

[0037] In the above-described embodiment, a wound electrode body is used as the electrode body. However, the electrode body is not limited to a wound electrode body as long as a positive electrode plate and a negative electrode plate face each other via a separator. Another example of the electrode body structure is a stacked electrode body in which multiple positive electrode plates and negative electrode plates are stacked in order with a separator interposed therebetween. To manufacture a negative electrode plate for this type of stacked electrode body, a two-dot chain line L in FIG. N6 It is advisable to perform cutting along the short direction S as shown in for each negative electrode tab 22t. Although detailed explanation will be omitted, the positive electrode plates are fabricated in a similar manner. Then, multiple positive electrode plates and multiple negative electrode plates are stacked with separators interposed between them so that the positive electrode tabs are stacked in the same position and the negative electrode tabs of the negative electrode plates are stacked in the same position. In this way, a laminated electrode body can be fabricated.

[0038] Furthermore, the above-described embodiment is directed to a high-capacity electricity storage device 100 in which three wound electrode assemblies 40 are housed inside a battery case 50. However, the number of electrode assemblies housed in one battery case is not particularly limited and may be two or more (plural), or may be one. Furthermore, the electricity storage device 100 according to the above-described embodiment is a lithium-ion secondary battery in which lithium ions are the charge carrier. However, the electricity storage device disclosed herein is not limited to lithium-ion secondary batteries. The manufacturing process for other electricity storage devices (such as nickel-metal hydride batteries) also includes a step of cutting the active material-provided region and the core-exposed region of the electrode plate material with a laser, and therefore the technology disclosed herein can be applied without particular limitations.

[0039] Furthermore, the energy storage device 100 according to the above-described embodiment is a nonaqueous electrolyte secondary battery that uses a nonaqueous electrolyte as the electrolyte. However, the technology disclosed herein can also be applied to batteries other than nonaqueous electrolyte secondary batteries. Another example of the structure of an energy storage device is an all-solid-state battery. In this all-solid-state battery, a solid electrolyte layer formed from a solid electrolyte in a sheet form is used as a separator interposed between a positive electrode plate and a negative electrode plate. In this all-solid-state battery, the separator and the electrolyte are integrated and contained within the electrode body, thereby preventing leakage of the electrolyte. The manufacturing process for this type of all-solid-state battery also includes a step of laser cutting the active material-containing region and the core-exposed region of the electrode plate material, so the technology disclosed herein can be applied without particular restrictions.

[0040] Although the present invention has been described in detail above, the above description is merely an example, and the technology disclosed herein includes various modifications and alterations of the above-described specific examples. [Explanation of symbols]

[0041] 10: Positive electrode plate 12: Positive electrode core 12t: Positive electrode tab 14: Positive electrode active material layer 16:Protective layer 20: Negative electrode plate 20A:Negative plate material 20b: Plate main body 20b1 :Edge 22: Negative electrode core 22t: Negative electrode tab 24:Negative electrode active material layer 30: Separator 40:Wound electrode body 42: Positive electrode tab group 44: Negative electrode tab group 50: Battery case 52: Exterior body 60: Positive terminal 65: Negative terminal 70: Positive electrode current collecting part 75: Negative electrode current collector 90: Gasket 100: Energy storage device A1: Negative electrode active material applied region A2: Negative electrode core exposed area

Claims

1. a preparation step of preparing a strip-shaped electrode plate material before tab cutting; a tab cutting process in which a pulse laser is irradiated onto the electrode plate material while the electrode plate material is being transported in the longitudinal direction, thereby producing an electrode plate having a plurality of electrode tabs at the ends of the electrode plate material in the lateral direction; Equipped with In the tab cutting step, an average output of the pulse laser per unit time is controlled to 300 W to 1000 W.

2. 2. The method for manufacturing an electrode plate according to claim 1, wherein the relative moving speed of the pulse laser with respect to the conveying speed of the electrode plate material is controlled to 110% to 140%.

3. The method for manufacturing an electrode plate according to claim 1, wherein the pulse width of the pulse laser is controlled to 30 ns to 120 ns.

4. The method for manufacturing an electrode plate according to claim 1, wherein the frequency of the pulsed laser is controlled to be in the range of 500 kHz to 2100 kHz.

5. The method for manufacturing an electrode plate according to claim 1, wherein the overlap rate of the pulsed laser is controlled to 96% to 99%.

6. The electrode plate is a negative electrode plate comprising a negative electrode core made of copper or a copper alloy and a negative electrode active material layer containing a carbon material as an electrode active material. The method for manufacturing an electrode plate according to any one of claims 1 to 5.

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