Positive electrode plate, non-aqueous electrolyte secondary battery, and method for manufacturing positive electrode plate

Abstract

To provide a positive electrode plate obtained by a positive electrode plate production method where slurry for forming a protective layer has good applicability.SOLUTION: A positive electrode plate comprises a protective layer and an active material layer including a positive electrode active material that are on a surface of metal foil. The active material layer and the protective layer are adjacent to each other in a plan view of the positive electrode plate. The protective layer contains magnesia having a specific surface area of 5.0 m2 / g or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a positive electrode plate, a non-aqueous electrolyte secondary battery, and a method for manufacturing a positive electrode plate.

Background Art

[0002] A positive electrode plate having an active material layer on the surface of a metal foil and a protective layer adjacent to the side edge portion of the active material layer is known (for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The protective layer is formed by applying a slurry containing an inorganic filler to the surface of the metal foil. When magnesia is used as the inorganic filler, the static viscosity of the slurry may increase. An increase in the static viscosity of the slurry can make it difficult to spread the slurry on the surface of the metal foil, and thus can cause defects in the protective layer.

[0005] The present disclosure aims to provide a method for manufacturing a positive electrode plate, a positive electrode plate, and a non-aqueous electrolyte secondary battery including the same, in which the coatability of a slurry for forming a protective layer is good.

Means for Solving the Problems

[0006] 〔1〕 A positive electrode plate having an active material layer containing a positive electrode active material and a protective layer on the surface of a metal foil, the active material layer and the protective layer are adjacent to each other in a plan view of the positive electrode plate, the protective layer has a specific surface area of 5.0 m2 A positive electrode plate containing magnesia with a content of 1 g or less. 〔2〕 The specific surface area of the magnesia contained in the protective layer is 4.0 m 2 / g or less, and the positive electrode plate according to 〔1〕. 〔3〕 The protective layer contains 15% by weight or more and 25% by weight or less of the magnesia based on the total amount of the protective layer, and the positive electrode plate according to 〔1〕 or 〔2〕. 〔4〕 The protective layer further contains a binder, and the positive electrode plate according to any one of 〔1〕 to 〔3〕. 〔5〕 The protective layer further contains a conductive carbon material, and the positive electrode plate according to any one of 〔1〕 to 〔4〕. 〔6〕 A non-aqueous electrolyte secondary battery including the positive electrode plate according to any one of 〔1〕 to 〔5〕. 〔7〕 A method for manufacturing a positive electrode plate for obtaining a positive electrode plate from a positive electrode precursor, wherein the positive electrode precursor has an active material layer containing a positive electrode active material and a protective layer on the surface of a metal foil, in a plan view of the positive electrode precursor, the active material layer and the protective layer are adjacent to each other, the manufacturing method includes a step (S1) of preparing the positive electrode precursor, the step (S1) includes a step of applying a slurry for forming the protective layer on the surface of the metal foil, the slurry contains magnesia with a specific surface area of 5.0 m 2 / g or less, and the method for manufacturing a positive electrode plate. 〔8〕 The specific surface area of the magnesia contained in the slurry is 4.0 m 2 / g or less, and the method for manufacturing a positive electrode plate according to 〔7〕. 〔9〕 The manufacturing method further includes a step (S2) of cutting the positive electrode precursor with a laser, the step (S2) includes a step of cutting the protective layer, and the method for manufacturing a positive electrode plate according to 〔7〕 or 〔8〕. 〔10〕 The positive electrode plate has an electrode tab, the step (S2) includes a step of forming the electrode tab by cutting the positive electrode precursor with the laser, and the method for manufacturing a positive electrode plate according to 〔9〕. 〔11〕 The method for manufacturing a positive electrode plate according to 〔9〕 or 〔10〕, wherein the laser is a continuous wave laser. 〔12〕 The method for manufacturing a positive electrode plate according to 〔11〕, wherein the output of the continuous wave laser in the step (S2) is 400 W or more and 1200 W or less. 〔13〕 The method for manufacturing a positive electrode plate according to 〔11〕 or 〔12〕, wherein the scanning speed of the continuous wave laser in the step (S2) is 7660 mm / second or less.

Advantages of the Invention

[0007] According to the present disclosure, a method for manufacturing a positive electrode plate and a positive electrode plate having good coatability of a slurry for forming a protective layer can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0009] (Positive Electrode Plate) FIG. 1 is a schematic plan view showing an example of a positive electrode plate according to an embodiment of the present disclosure. The positive electrode plate 10 can be used in a battery, for example, in a non-aqueous electrolyte secondary battery. The positive electrode plate 10 has an active material layer 12 containing a positive electrode active material and a protective layer 13 on the surface of a metal foil 11, and the active material layer 12 and the protective layer 13 are adjacent to each other in a plan view of the positive electrode plate 10. The active material layer 12 and the protective layer 13 can be provided on one or both sides of the metal foil 11. The positive electrode plate 10 can have an electrode tab 14 that serves as a connection portion to an external terminal (positive electrode terminal). The electrode tab 14 can be provided so as to protrude outward from the protective layer 13 provided at the side edge portion of the positive electrode plate 10 in a plan view of the positive electrode plate 10 (FIG. 1). The electrode tab 14 can have a region where the surface of the metal foil 11 is exposed where the active material layer 12 and the protective layer 13 are not formed on the surface of the metal foil 11, and may include a part of the protective layer 13.

[0010] The metal foil 11 functions as a positive electrode current collector and can be formed using an aluminum material such as aluminum and aluminum alloy.

[0011] The active material layer 12 may contain one or both of a binder and a conductive assistant in addition to the positive electrode active material. Examples of the positive electrode active material include lithium transition metal oxides such as layered or spinel type (for example, LiNiCoMnO 2 、LiNiO 2 、LiCoO 2 、LiFeO 2 、LiMn 2 O 4 、LiNi 0.5 Mn 1.5 O 4 、LiCrMnO 4 、LiFePO 4 、LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 ).

[0012] Examples of the binder material include one or more selected from the group consisting of styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVdF), and polytetrafluoroethylene (PTFE).

[0013] Examples of the conductive auxiliary agent include carbon materials. Examples of the carbon materials include one or more selected from the group consisting of fibrous carbon, carbon black (such as acetylene black and ketjen black), coke, and activated carbon. Examples of the fibrous carbon include carbon nanotubes (CNT). The CNT may be a single-walled carbon nanotube (SWCNT) or a multi-walled carbon nanotube such as a double-walled carbon nanotube (DWCNT).

[0014] The protective layer 13 is preferably provided along the side edge of the active material layer 12 at the side edge portion where the electrode tab 14 of the positive electrode plate 10 is provided. The protective layer 13 usually has a lower electric conductivity than the metal foil 11 and the active material layer 12. By providing the protective layer 13 adjacent to the active material layer 12, it is possible to suppress the contact between the metal foil 11 of the positive electrode plate 10 and the negative electrode active material layer due to damage to the separator of the electrode body included in the battery, and to suppress the occurrence of an internal short circuit of the battery.

[0015] The protective layer 13 contains magnesia (MgO) (hereinafter also referred to as "this MgO") having a specific surface area (BET) of 5.0 m 2 / g or less. This MgO is preferably in the form of particles. The specific surface area of this MgO is preferably 4.5 m 2 / g or less, more preferably 4.0 m 2 / g or less, usually 0.5 m 2 / g or more, and 1.0 m 2It may also be 1 / g or more. As will be described later, the protective layer 13 is formed by applying a slurry containing this MgO onto the metal foil 11. The slurry with an increased static viscosity tends to be difficult to spread when applied onto the metal foil 11. Since the slurry containing this MgO can suppress the increase in static viscosity, it has excellent coatability of the slurry and can suppress the occurrence of coating unevenness when applied onto the metal foil 11. Thereby, it can be expected that the occurrence of defects in the protective layer 13 formed on the metal foil 11 can be suppressed.

[0016] The specific surface area of magnesia can be adjusted by controlling the particle size of magnesia, the firing temperature and firing time during the production of magnesia, etc. The specific surface area of this MgO can be calculated by an adsorption method in which liquid nitrogen is adsorbed on the surface of this MgO and the specific surface area is determined from the adsorption amount.

[0017] In addition to this MgO, the protective layer 13 may contain one or both of a binder and a conductive carbon material, and may further contain filler particles other than this MgO. Examples of the binder include one or more selected from the group consisting of polyimide (PI), polyamideimide (PAI), and polyvinylidene fluoride (PVdF). Examples of the conductive carbon material include one or more selected from the group consisting of carbon black (acetylene black, ketjen black, etc.), graphite, carbon nanotubes, carbon nanohorns, graphene, and fullerenes. Examples of the filler particles other than this MgO include insulating filler particles, such as inorganic oxide particles, nitride particles, metal hydroxide particles, viscous mineral particles, and glass particles other than this MgO.

[0018] The protective layer 13 preferably contains 15% by weight or more and 25% by weight or less of this MgO, may contain 17% by weight or more and 23% by weight or less, and may contain 18% by weight or more and 22% by weight or less, based on the total amount of the protective layer 13. The content of the binder in the protective layer 13 may be 5% by weight or more and 60% by weight or less, or 10% by weight or more and 50% by weight or less, based on the total amount of the protective layer 13. The content of the conductive carbon material in the protective layer 13 may be 0.1% by weight or more and 10% by weight or less, or 1% by weight or more and 5% by weight or less, based on the total amount of the protective layer 13. The content of this MgO with respect to the total amount of the filler particles contained in the protective layer 13 is preferably 80% by weight or more and 100% by weight or less, more preferably 90% by weight or more and 100% by weight or less, and may be 95% by weight or more and 100% by weight or less.

[0019] As described later, when the protective layer 13 is cut with a laser during the production of the positive electrode plate 10, burning occurs in the protective layer 13. The burning of the protective layer 13 can cause false detection in the image inspection of the positive electrode plate 10 or the like. Since the protective layer 13 of the present embodiment contains magnesia, compared with the protective layer formed using alumina (Al 2 O 3 ) instead of magnesia, the burning width generated when cutting with a laser can be reduced. Therefore, false detection in the image inspection of the positive electrode plate 10 or the like can be suppressed.

[0020] (Method for manufacturing a positive electrode plate) FIG. 2 is a schematic plan view showing an example of a positive electrode raw sheet according to an embodiment of the present disclosure. The method for manufacturing the positive electrode plate 10 is a method for obtaining the positive electrode plate 10 from the positive electrode raw sheet 20, for example, the method for manufacturing the positive electrode plate 10 shown in FIG. 1 described above. The positive electrode raw sheet 20 has an active material layer 12 containing a positive electrode active material and a protective layer 13 on the surface of the metal foil 11, and the active material layer 12 and the protective layer 13 are adjacent to each other in a plan view of the positive electrode raw sheet 20. As shown in FIG. 2, for example, the protective layer 13 can be provided adjacent to both side edges of the active material layer 12 on the positive electrode raw sheet 20. The active material layer 12 and the protective layer 13 can be provided on one or both sides of the metal foil 11. Examples of the materials constituting the metal foil 11, the active material layer 12, and the protective layer 13 are those described above. The positive electrode raw sheet 20 is usually in a strip shape and has a length and width capable of cutting out a plurality of positive electrode plates 10.

[0021] The method for manufacturing the positive electrode plate 10 includes a step (S1) of preparing the positive electrode raw sheet 20. The step (S1) includes a step (S1b) of applying a slurry for forming the protective layer 13 on the surface of the metal foil 11, and the slurry contains this MgO. The protective layer 13 is formed by drying the applied slurry or the like. The specific surface area of this MgO contained in the slurry is within the range described above.

[0022] The slurry can be prepared by mixing this MgO and a dispersion medium. The slurry may further contain one or both of a binder and a conductive carbon material. Examples of the binder and the conductive carbon material are those described above. The slurry can be prepared, for example, by adding this MgO to a mixed solution of a binder and a dispersion medium and mixing them, and then adding a conductive carbon material and mixing them.

[0023] The slurry can be applied by a known method, for example, by a slot die coater or a roll coater.

[0024] The process (S1) may further include a step (S1a) of applying a positive electrode slurry containing a positive electrode active material for forming the active material layer 12 onto the surface of the metal foil 11. After drying the applied positive electrode slurry and forming the active material layer 12 by compression or the like as necessary, it is preferable to perform the above step (S1b). In this case, the slurry applied in the step (S1b) may be applied so as to be adjacent to the active material layer 12.

[0025] In the method for manufacturing the positive electrode plate 10, for example, in order to obtain the positive electrode plate 10 from the positive electrode raw sheet 20, the positive electrode raw sheet 20 is cut along the first cutting line L1 and the second cutting line L2. The first cutting line L1 can be set linearly so as to divide the width of the active material layer 12 (the length in the direction perpendicular to the first cutting line L1) into two in the region where the active material layer 12 of the positive electrode raw sheet 20 is formed, as shown in FIG. 2 for example. The second cutting line L2 can be set in the region where the protective layer 13 of the positive electrode raw sheet 20 is formed and the region where the metal foil 11 is exposed so as to form the side edge portion on the side where the electrode tab 14 of the positive electrode plate 10 is provided, as shown in FIG. 2 for example. The cutting of the positive electrode raw sheet 20 along the first cutting line L1 and the second cutting line L2 can be performed by a laser, a cutting blade, a mold, a rotary slitter, a cutter, or the like. The laser may be a continuous wave laser (CW laser) or a pulsed laser. The cutting methods used for cutting along the first cutting line L1 and the second cutting line L2 may be the same or different.

[0026] The manufacturing method of the positive electrode plate 10 includes a step (S2) of cutting the positive electrode raw sheet 20 with a laser, and the step (S2) preferably includes a step of cutting the protective layer 13. The step (S2) may include a step of forming the electrode tab 14 by cutting the positive electrode raw sheet 20 with a laser. When forming the electrode tab 14, in the positive electrode raw sheet 20, the protective layer 13 may be cut and the region where the metal foil 11 is exposed may be cut with a laser. The step (S2) may be a step of cutting the positive electrode raw sheet 20 along the second cutting line L2 shown in FIG. 2. Since the melting point of magnesia is higher than that of alumina, the protective layer 13 containing this MgO can reduce the char width generated when cut with a laser as compared with the protective layer using alumina. Thereby, false detection in the image inspection etc. of the positive electrode plate 10 can be suppressed.

[0027] In the step (S2), it is preferable to use a CW laser. Since the CW laser has a relatively small peak output compared to the pulsed laser, it is possible to suppress the protective layer 13 from being blown off by the impact during laser irradiation. When using a CW laser in the step (S2), the output is preferably 400 W or more and 1200 W or less, may be 400 W or more and 1000 W or less, may be 500 W or more and 800 W or less, may be 500 W or more and less than 700 W, or may be 500 W or more and 600 W or less.

[0028] When using a CW laser in the step (S2), the scanning speed is preferably 7660 mm / second or less, may be 3000 mm / second or more and 7500 mm / second or less, or may be more than 6000 mm / second and 7000 mm / second or less. The scanning speed represents the speed when the positive electrode raw sheet and the laser move relative to each other. When only one of the positive electrode raw sheet and the laser is moved, the moving speed of the moving one becomes the scanning speed. When both the positive electrode raw sheet and the laser are moved in opposite directions respectively, the sum of the moving speeds of the positive electrode raw sheet and the laser respectively becomes the scanning speed.

[0029] Since magnesia has a higher melting point than alumina, compared with a protective layer using alumina instead of magnesia, the protective layer 13 containing this MgO is less likely to cause re-welding after cutting with a laser. Therefore, as described above, even when reducing the output or increasing the scanning speed during cutting with a CW laser, re-welding can be suppressed, and while achieving good cutting quality (the processing width of the cut portion, the length of burrs, and the heat-affected zone width), the manufacturing efficiency of the positive electrode plate 10 can be improved. In contrast, for a protective layer using alumina, in order to suppress re-welding, it is necessary to set the laser output to, for example, 700 W or more and the scanning speed to 5000 mm / second or less. It is difficult to reduce the laser output and increase the scanning speed, and it is difficult to improve the manufacturing efficiency. In a protective layer using alumina, since the heat-affected zone width increases due to cutting with a laser as described above, the cutting quality of the positive electrode plate is also likely to deteriorate.

[0030] When using a CW laser in step (S2), the spot diameter of the CW laser may be, for example, 10 μm or more and 60 μm or less, or may be 20 μm or more and 50 μm or less.

[0031] (Non-aqueous electrolyte secondary battery) The non-aqueous electrolyte secondary battery includes the positive electrode plate described above. A non-aqueous electrolyte secondary battery usually includes an electrode body and an electrolyte. The non-aqueous electrolyte secondary battery may further include a case for housing the electrode body and the electrolyte. The electrode body has a structure in which a separator is sandwiched between the active material layer of the positive electrode plate described above and the negative electrode active material layer of the negative electrode plate. The electrode body may be a wound electrode body or a laminated electrode body. In a non-aqueous electrolyte secondary battery, the bundle of electrode tabs of the positive electrode plate is connected to the positive electrode terminal, and the bundle of electrode tabs of the negative electrode plate is connected to the negative electrode terminal.

[0032] The negative electrode plate has a negative electrode active material layer on a negative electrode current collector. The negative electrode current collector is, for example, a metal foil made of a copper material such as copper and copper alloy. The negative electrode active material layer contains a negative electrode active material and may further contain one or both of a binder and a conductive assistant.

[0033] As the negative electrode active material, carbon-based active materials containing carbon (C) atoms such as graphite (graphite); metal-based active materials containing metal elements such as simple metals or metal oxides containing elements selected from the group consisting of silicon (Si), tin (Sn), antimony (Sb), bismuth (Bi), titanium (Ti), and germanium (Ge) can be mentioned. As the binder, cellulose-based binders such as carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), etc. can be mentioned. As the conductive aid, carbon materials such as fibrous carbon, carbon black (for example, acetylene black, ketjen black), coke, activated carbon, etc. can be mentioned. The fibrous carbon includes those described above.

[0034] As the separator, porous sheets (films, non-woven fabrics, etc.) made of resins such as polyethylene, polypropylene, polyester, cellulose, polyamide, etc. can be mentioned. The porous sheet may have a single-layer structure or a multi-layer structure of two or more layers.

[0035] As the electrolyte, non-aqueous electrolytes can be mentioned, for example, those obtained by containing a supporting salt in a non-aqueous solvent such as an organic solvent. Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC), etc. Examples of the supporting salt include lithium perchlorate (LiClO 4 ) and lithium hexafluorophosphate (LiPF 6 ), etc.

[0036] The case is a housing for accommodating the electrode body. The case is preferably made of metal and can be formed using, for example, aluminum, aluminum alloy, iron, or iron alloy, etc.

Examples

[0037] Hereinafter, the present disclosure will be described more specifically by showing examples and comparative examples. [Preparation of Samples] The inorganic oxide particles shown in Table 1 were added to a mixture of a dispersion medium and polyvinylidene fluoride (PVdF), and the mixture was stirred for 120 minutes at a rotation speed of the stirring blade of 2000 to 6000 rpm. After that, a conductive carbon material (acetylene black, etc.) was added, and the mixture was stirred for 30 minutes at a rotation speed of the stirring blade of 2000 to 6000 rpm to prepare a slurry.

[0038] The slurry prepared above was applied to both sides of an aluminum foil using an applicator with a coating thickness of 125 μm, and then thoroughly dried at a temperature of about 120° C. to produce samples (1) to (4) in which a protective layer was formed on the surface of the aluminum foil.

[0039] [Measurement of the specific surface area of ​​inorganic oxide particles] Liquid nitrogen was adsorbed onto the surfaces of inorganic oxide particles shown in Table 1. The specific surface area was calculated from the amount of liquid nitrogen adsorbed onto the surfaces of the inorganic oxide particles by the adsorption method. The results are shown in Table 1.

[0040] [Measurement of slurry viscosity] The slurries to obtain samples (1) to (4) were subjected to a temperature of 23 to 28°C and a shear rate of 0.01 to 10,000 s -1 The viscosity at 1000 g / mol was measured using an MCR rheometer manufactured by Anton Paar. The results are shown in Figure 3. In Figure 3, the inorganic oxide particles explaining each plot indicate the type of inorganic oxide particles contained in each slurry (Table 1).

[0041] Inorganic oxide particles with a specific surface area of ​​3.7 m 2 / g and 4.7m 2 / g Al 2 O 3 The viscosity of the slurry prepared using the above procedure was measured by the above procedure and was found to be the same as that of the slurry used to obtain sample (4).

[0042] From the graph in Figure 3, it can be seen that the static viscosity of the slurry varies depending on the specific surface area of ​​MgO. 2 O 3 In the slurry using Al, unlike the slurry using MgO,2 O 3 It can be seen that the static viscosity does not change depending on the specific surface area of O.

[0043] [Evaluation of the coatability of the slurry] In the preparation of the sample, when the slurry was applied to the surface of the aluminum foil, those that spread easily were evaluated as "A", and those that were difficult to spread were evaluated as "B". The results are shown in Table 1.

[0044]

Table 1

[0045] [Evaluation of cutting with a laser] Using a continuous wave laser, in the range of an output of 400 to 1200 W and a scanning speed of 7660 mm / s or less, the areas where the protective layers of Sample (2) and Sample (4) were formed were cut. The protective layers of the cut parts were observed with a microscope to confirm the presence or absence of re-welding, and the processing width, char width, and burr length (all in the length in the direction perpendicular to the cutting line in plan view) of the cut parts were measured. The processing width was defined as the width of the part where the protective layer disappeared due to cutting of the sample. The char width was defined as the width where the protective layer was discolored due to cutting. The results of the presence or absence of re-welding are shown in Table 2, and the measurement results of the char width with respect to the laser output during cutting are shown in FIGS. 4 and 5. FIG. 4 is a graph showing the char width of Sample (2), and FIG. 5 is a graph showing the char width of Sample (4). The plots indicated by white circles in the graphs represent the average values of the char width. From FIGS. 4 and 5, it can be seen that the char width of Sample (2) is smaller than the char width of Sample (4). The processing widths and burr lengths of Sample (2) and Sample (4) were both within the range acceptable as the cutting quality of the positive electrode plate.

[0046]

Table 2

Explanation of symbols

[0047] 10 Positive electrode plate, 11 Metal foil, 12 Active material layer, 13 Protective layer, 14 Electrode tab, 20 Positive electrode raw sheet.

Claims

1. A positive electrode plate having an active material layer containing a positive electrode active material and a protective layer on the surface of a metal foil, wherein the active material layer and the protective layer are adjacent to each other in a plan view of the positive electrode plate, The protective layer contains magnesia having a specific surface area of 1.0 m2 / g or more and 5.0 m ２ / g or less, and is a positive electrode plate (however, excluding the case where the protective layer is formed on the entire surface of the active material layer in a plan view of the positive electrode plate).

2. The specific surface area of the magnesia contained in the protective layer is 4.0 m ２ / g or less. The positive electrode plate according to claim 1.

3. The positive electrode plate according to claim 1, wherein the protective layer contains 15% by weight or more and 25% by weight or less of magnesia based on the total amount of the protective layer.

4. The positive electrode plate according to claim 1, wherein the protective layer further contains a binder.

5. The positive electrode plate according to claim 1, wherein the protective layer further contains a conductive carbon material.

6. A non-aqueous electrolyte secondary battery including the positive electrode plate according to any one of claims 1 to 5.

7. A method for manufacturing a positive electrode plate for obtaining a positive electrode plate from a positive electrode green sheet, wherein the positive electrode green sheet has an active material layer containing a positive electrode active material and a protective layer on the surface of a metal foil (however, excluding the case where the protective layer is formed on the entire surface of the active material layer in a plan view of the positive electrode green sheet), wherein the active material layer and the protective layer are adjacent to each other in a plan view of the positive electrode green sheet, the manufacturing method includes a step (S1) of preparing the positive electrode green sheet, and the step (S1) includes a step of applying a slurry for forming the protective layer on the surface of the metal foil. The slurry contains magnesia with a specific surface area of 1.0 m2 / g or more and 5.0 m ２ / g or less, and is a method for manufacturing a positive electrode plate.

8. The specific surface area of the magnesia contained in the slurry is 4.0 m ２ / g or less. The method for manufacturing a positive electrode plate according to claim 7.

9. The manufacturing method further includes a step (S2) of cutting the positive electrode green sheet with a laser, and the step (S2) includes a step of cutting the protective layer. The method for manufacturing a positive electrode plate according to claim 7.

10. The positive electrode plate has an electrode tab, and the step (S2) includes a step of forming the electrode tab by cutting the positive electrode green sheet with the laser. The method for manufacturing a positive electrode plate according to claim 9.

11. The laser is a continuous wave laser. The method for manufacturing a positive electrode plate according to claim 9 or 10.

12. The output of the continuous wave laser in the step (S2) is 400 W or more and 1200 W or less. The method for manufacturing a positive electrode plate according to claim 11.

13. The scanning speed of the continuous wave laser in the step (S2) is 7660 mm / second or less. The method for manufacturing a positive electrode plate according to claim 11.

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