Manufacturing method for non-aqueous secondary batteries

Abstract

To provide a method of manufacturing a nonaqueous secondary battery, with which a resistance distribution can be uniformed on an electrode plate.SOLUTION: There is provided a method of manufacturing a nonaqueous secondary battery, the nonaqueous secondary battery including an electrode body 20 in which a positive electrode sheet 21 and a negative electrode sheet 24 are stacked via a separator 27, and a nonaqueous electrolyte containing a film forming agent including a lithium salt. The method of manufacturing a nonaqueous secondary battery includes: a coating step of manufacturing the negative electrode sheet 24 by coating a negative electrode mixture layer 26 on a negative electrode current collector 25, the negative electrode mixture layer including a negative electrode active material and an additive material including a sodium salt; and a rolling step of rolling the negative electrode sheet 24 on which the negative electrode mixture layer 26 is coated. During the coating step, the orientation of the negative electrode active material is adjusted such that a resistance distribution of the negative electrode sheet 24 after rolling is uniform, on the basis of a relationship between BET specific area differences of the negative electrode active material before and after rolling and orientation of the negative electrode active material.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a non-aqueous secondary battery.

Background Art

[0002] In the method for manufacturing a non-aqueous secondary battery described in Patent Document 1, a film-forming material containing lithium is added to a non-aqueous electrolyte. The film-forming agent is lithium bisoxalate borate (LiBOB), which is an example of a lithium salt. An electrode assembly used for a non-aqueous secondary battery contains a sodium salt. When the electrode assembly contains a large amount of sodium, BOB ions ionized from LiBOB combine with Na ions ionized from the sodium salt to form a NaBOB film.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] Incidentally, in the method for manufacturing a non-aqueous secondary battery described in the above-mentioned Patent Document 1, the electrolyte solution permeates into the electrode plate from the end portion of the electrode plate. Further, the diffusion rate of Na ions dissolved in the electrolyte solution is faster than that of BOB ions. For this reason, generation of NaBOB in the central portion of the electrode plate prevents BOB ions from spreading to the central portion of the electrode plate. Then, portions with insufficient LiBOB film are formed in the central portion of the electrode plate. When charge and discharge are repeated in a non-aqueous secondary battery using such an electrode plate, decomposition of the electrolyte solution becomes remarkable in portions where the film-forming agent is relatively scarce. Then, a high-resistance film is formed in portions where the film-forming material is insufficient, causing lithium precipitation. In the above method for manufacturing a non-aqueous secondary battery, uniformization of resistance distribution in the electrode plate is required in order to suppress the occurrence of lithium precipitation.

Means for Solving the Problem

[0005] A method for manufacturing a non-aqueous secondary battery that solves the above problems comprises an electrode body in which a positive electrode sheet and a negative electrode sheet are laminated with a separator in between, and a non-aqueous electrolyte containing a film-forming agent containing a lithium salt, and includes a coating step for manufacturing the negative electrode sheet by coating a negative electrode composite layer containing a negative electrode active material and an additive containing a sodium salt onto a negative electrode substrate, and a rolling step for rolling the negative electrode sheet coated with the negative electrode composite layer, wherein in the coating step, the orientation of the negative electrode active material is adjusted based on the relationship between the difference in BET specific surface area of ​​the negative electrode active material before and after rolling and the orientation of the negative electrode active material, so that the resistance distribution of the negative electrode sheet after rolling becomes uniform.

[0006] According to the above configuration, increasing the orientation of the negative electrode active material reduces the difference in specific surface area before and after rolling. Therefore, the specific surface area can be changed by adjusting the orientation of the negative electrode active material. By utilizing this, the resistance distribution in the negative electrode sheet can be made uniform by adjusting the orientation of the negative electrode active material.

[0007] A method for manufacturing a non-aqueous secondary battery that solves the above problems comprises an electrode body in which a positive electrode sheet and a negative electrode sheet are laminated with a separator in between, and a non-aqueous electrolyte containing a film-forming agent containing a lithium salt, and comprises a coating step for manufacturing the negative electrode sheet by coating a negative electrode composite layer containing a negative electrode active material and an additive containing a sodium salt onto a negative electrode substrate, and a rolling step for rolling the negative electrode sheet coated with the negative electrode composite layer, wherein the negative electrode composite layer comprises end regions including both ends of the negative electrode sheet into which the non-aqueous electrolyte penetrates from both ends, and a central region located between the two end regions, and in the coating step, the orientation of the negative electrode active material in the central region and the end regions is adjusted based on the relationship between the BET specific surface area of ​​the negative electrode active material and the orientation of the negative electrode active material, such that the BET specific surface area of ​​the negative electrode active material in the central region after rolling is larger than the BET specific surface area of ​​the negative electrode active material in the end regions.

[0008] According to the above configuration, increasing the orientation of the negative electrode active material reduces the difference in specific surface area before and after rolling. Therefore, the specific surface area can be changed by adjusting the orientation of the negative electrode active material. By utilizing this, the resistance distribution in the negative electrode sheet can be made uniform by adjusting the orientation of the negative electrode active material.

[0009] In the above method for manufacturing a non-aqueous secondary battery, the coating step preferably includes a step of applying a magnetic field to the negative electrode substrate after coating it with the negative electrode composite layer, so that it becomes oriented to achieve a desired BET specific surface area. [Effects of the Invention]

[0010] According to the present invention, the resistance distribution in the electrode plate can be made uniform. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view showing the general configuration of a cell in a non-aqueous secondary battery. [Figure 2] This is a diagram showing a portion of the electrode body unfolded. [Figure 3] This flowchart shows the orientation calculation process for a non-aqueous secondary battery manufacturing method. [Figure 4] This figure shows the relationship between the position of the electrode plates and the resistance ratio of a non-aqueous secondary battery. [Figure 5] This is an illustrative diagram showing the orientation of the active material in a non-aqueous secondary battery. [Figure 6] This figure shows the relationship between the density and specific surface area of ​​the active material in a non-aqueous secondary battery. [Figure 7] This figure shows the relationship between the specific surface area of ​​the active material in a non-aqueous secondary battery and the resistance ratio of the electrode plates. [Figure 8] This figure shows the relationship between the position of the electrode plates and the resistance ratio of a non-aqueous secondary battery. [Figure 9] This figure shows the relationship between the specific surface area of ​​the active material in a non-aqueous secondary battery and the resistance ratio of the electrode plates. [Figure 10] This figure shows the relationship between the density and specific surface area of ​​the active material in a non-aqueous secondary battery. Description of Embodiments

[0012] [Present Embodiment] Hereinafter, an embodiment of a method for manufacturing a non-aqueous secondary battery will be described with reference to FIGS. 1 to 10. A lithium ion secondary battery will be described as an example of the non-aqueous secondary battery.

[0013] [Lithium ion secondary battery 10] As shown in FIG. 1, the lithium ion secondary battery 10 is a cell battery that is combined with a plurality of other lithium ion secondary batteries 10 and sealed in a resin or metal case to constitute a battery pack. The battery pack is used in hybrid vehicles and electric vehicles.

[0014] The lithium ion secondary battery 10 includes a battery case 11 and a lid body 12. The battery case 11 is a rectangular parallelepiped shape having an opening on an upper side. The lid body 12 seals the opening of the battery case 11. The battery case 11 and the lid body 12 are made of a metal such as aluminum or an aluminum alloy. For the lithium ion secondary battery 10, a sealed battery container is configured by attaching the lid body 12 to the battery case 11.

[0015] The lid body 12 is provided with two positive external terminals 13A and one negative external terminal 13B. The positive external terminal 13A and the negative external terminal 13B are used for charging and discharging electric power. An electrode assembly 20 is accommodated inside the battery case 11. A positive current collector 20A, which is an end portion on the positive side of the electrode assembly 20, is electrically connected to the positive external terminal 13A via a positive current collector member 14A. A negative current collector 20B, which is an end portion on the negative side of the electrode assembly 20, is electrically connected to the negative external terminal 13B via a negative current collector member 14B. In addition, a non-aqueous electrolyte is injected into the battery case 11 through a liquid injection hole (not shown). The shapes of the positive external terminal 13A and the negative external terminal 13B are not limited to the shapes shown in FIG. 1, and may be any shapes.

[0016] [Electrode assembly 20] As shown in Figure 2, the electrode assembly 20 is a flat wound body formed by winding a laminate obtained by laminating an elongated positive electrode sheet 21 and a negative electrode sheet 24 with a separator 27 interposed therebetween. The positive electrode sheet 21, the negative electrode sheet 24, and the separator 27 are laminated such that their respective longitudinal directions coincide with the longitudinal direction D1. The laminate before winding is laminated in the order of the positive electrode sheet 21, the separator 27, the negative electrode sheet 24, and the separator 27.

[0017] [Positive Electrode Sheet 21] The positive electrode sheet 21 includes a positive electrode current collector 22 and a positive electrode mixture layer 23. The positive electrode current collector 22 is a foil-shaped positive electrode base material formed in an elongated shape. The positive electrode mixture layer 23 is provided on each of two opposing surfaces of the positive electrode current collector 22. The positive electrode current collector 22 includes, at one end in the width direction D2, a positive electrode side uncoated portion 22A where the positive electrode mixture layer 23 is not formed and the positive electrode current collector 22 is exposed.

[0018] For the positive electrode current collector 22, a metal foil made of aluminum or an alloy containing aluminum as a main component is used. The positive electrode current collector 22 functions as a current collector for the positive electrode. In the wound body state, the opposing surfaces of the positive electrode side uncoated portion 22A provided in the positive electrode current collector 22 are pressed against each other to form the positive electrode side current collector portion 20A.

[0019] The positive electrode mixture layer 23 is a cured product of a liquid positive electrode mixture paste. The positive electrode mixture paste includes a positive electrode active material, a positive electrode solvent, a positive electrode conductive material, and a positive electrode binder. The positive electrode mixture layer 23 is formed by drying the positive electrode mixture paste and vaporizing the positive electrode solvent. Therefore, the positive electrode mixture layer 23 includes the positive electrode active material, the positive electrode conductive material, and the positive electrode binder.

[0020] The positive electrode active material is a lithium-containing composite oxide capable of intercalating and releasing lithium ions, which are charge carriers in the lithium-ion secondary battery 10. The lithium-containing composite oxide is an oxide containing lithium and other metallic elements other than lithium. The other metallic elements other than lithium are, for example, at least one selected from the group consisting of nickel, cobalt, manganese, vanadium, magnesium, molybdenum, niobium, titanium, tungsten, aluminum, and iron contained as iron phosphate in the lithium-containing composite oxide.

[0021] For example, lithium-containing composite oxides include lithium cobaltate (LiCoO2), lithium nickelate (LiNiO2), and lithium manganate (LiMn2O4). Another example is lithium-containing composite oxide, a ternary lithium-containing composite oxide containing nickel, cobalt, and manganese, which is lithium nickel-cobalt-manganate (LiNiCoMnO2). Yet another example is lithium iron phosphate (LiFePO4).

[0022] The positive electrode solvent is an NMP (N-methyl-2-pyrrolidone) solution, which is an example of an organic solvent. Examples of positive electrode conductive materials include carbon black such as acetylene black and Ketjenblack, carbon fibers such as carbon nanotubes and carbon nanofibers, and graphite. The positive electrode binder is an example of a resin component contained in the positive electrode composite paste. Examples of positive electrode binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), and styrene-butadiene rubber (SBR).

[0023] The positive electrode sheet 21 may have an insulating layer at the boundary between the uncoated portion 22A on the positive electrode side and the positive electrode composite layer 23. The insulating layer contains an inorganic component having insulating properties and a resin component that functions as a binder. The inorganic component is at least one selected from the group consisting of powdered boehmite, titania, and alumina. The resin component is at least one selected from the group consisting of PVDF, PVA, and acrylic.

[0024] [Negative electrode sheet 24] The negative electrode sheet 24 comprises a negative electrode current collector 25 and a negative electrode composite layer 26. The negative electrode current collector 25 is a foil-shaped negative electrode substrate formed in an elongated shape. The negative electrode composite layer 26 is provided on each of two opposing surfaces of the negative electrode current collector 25. The negative electrode current collector 25 has a negative electrode side unpainted portion 25A at one end in the width direction D2, which is located opposite the positive electrode side unpainted portion 22A, where the negative electrode composite layer 26 is not formed and the negative electrode current collector 25 is exposed.

[0025] The negative electrode current collector 25 is made of metal foil composed of copper or an alloy mainly composed of copper. The negative electrode current collector 25 functions as a current collector at the negative electrode. In the wound state, the unpainted negative electrode side portion 25A has opposing surfaces pressed against each other to form the negative electrode side current collector portion 20B.

[0026] The negative electrode composite layer 26 is a cured body of a liquid negative electrode composite paste. The negative electrode composite paste contains a negative electrode active material, a negative electrode solvent, a negative electrode thickener, and a negative electrode binder. The negative electrode composite layer 26 is formed when the negative electrode composite paste is dried and the negative electrode solvent vaporizes. Therefore, the negative electrode composite layer 26 contains the negative electrode active material, and further, as additives, a negative electrode thickener and a negative electrode binder. The negative electrode composite layer 26 may further contain additives such as a conductive material.

[0027] The negative electrode active material is a material capable of intercalating and releasing lithium ions. Examples of negative electrode active materials include carbon materials such as graphite, poorly graphitizable carbon, easily graphitizable carbon, and carbon nanotubes. The negative electrode solvent is, for example, water. As an example of a negative electrode thickener, CMC (carboxymethylcellulose) can be used as a thickener containing a sodium salt. The negative electrode binder can be the same as the positive electrode binder. As an example of a negative electrode binder, SAR (styrene-acrylic acid copolymer) can be used as a binder containing a sodium salt.

[0028] [Separator 27] The separator 27 prevents contact between the positive electrode sheet 21 and the negative electrode sheet 24, and holds the non-aqueous electrolyte between the positive electrode sheet 21 and the negative electrode sheet 24. When the electrode body 20 is immersed in the non-aqueous electrolyte, the non-aqueous electrolyte penetrates from the ends in the width direction D2 of the separator 27 toward the center.

[0029] The separator 27 is a nonwoven fabric made of polypropylene or the like. As the separator 27, for example, porous polymer membranes such as porous polyethylene membranes, porous polyolefin membranes, and porous polyvinyl chloride membranes, and ion-conductive polymer electrolyte membranes can be used.

[0030] [Nonaqueous electrolyte] A non-aqueous electrolyte is a composition containing a supporting salt in a non-aqueous solvent. As the non-aqueous solvent, one or more materials selected from the group consisting of propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, etc., can be used. As the supporting salt, one or more lithium compounds (lithium salts) selected from LiPF6, LiBF4, LiClO4, LiAsF6, LiCF3SO3, LiC4F9SO3, LiN(CF3SO2)2, LiC(CF3SO2)3, LiI, LiBOB (lithium bisoxalate borate), etc., can be used.

[0031] In this embodiment, ethylene carbonate is used as the non-aqueous solvent. LiBOB, as a lithium salt of the film-forming agent, is added to the non-aqueous electrolyte. For example, LiBOB is added to the non-aqueous electrolyte so that the concentration of LiBOB in the non-aqueous electrolyte is between 0.001 and 0.1 [mol / L].

[0032] [Manufacturing method] Next, the manufacturing method of the lithium-ion secondary battery 10 will be described with reference to Figures 3 to 8.

[0033] A method for manufacturing a lithium-ion secondary battery 10 includes a coating step of manufacturing a negative electrode sheet 24 by coating a negative electrode composite layer 26 onto a negative electrode current collector 25, and a rolling step of rolling the negative electrode sheet 24 coated with the negative electrode composite layer 26. In the coating step, the orientation of the negative electrode active material is adjusted based on the relationship between the difference in BET specific surface area of ​​the negative electrode active material before and after rolling and the orientation of the negative electrode active material, so that the resistance distribution of the negative electrode sheet 24 after rolling becomes uniform.

[0034] In this embodiment, the negative electrode composite layer 26 comprises end regions including both ends of the negative electrode sheet 24 into which the non-aqueous electrolyte permeates from both ends, and a central region located between the two end regions. In the coating process, the orientation of the negative electrode active material in the central region and the end regions is adjusted based on the relationship between the BET specific surface area of ​​the negative electrode active material and the orientation of the negative electrode active material, so that the BET specific surface area of ​​the negative electrode active material in the central region after rolling is greater than the BET specific surface area of ​​the negative electrode active material in the end regions. The coating process includes coating the negative electrode composite layer 26 onto the negative electrode current collector 25 and then applying a magnetic field to achieve an orientation that results in a desired BET specific surface area. Hereinafter, BET specific surface area will be referred to as specific surface area.

[0035] [Resistance distribution of the negative electrode sheet] As shown in Figure 3, the resistance distribution along the imaginary line connecting both ends of the negative electrode sheet 24 is mountain-shaped with a convex center, and is symmetrical with respect to the center. Figure 3 shows the resistance ratio with the center being 100%. The base of the peak is the end region where the change in resistance is small. The non-aqueous electrolyte penetrates from both ends of the negative electrode sheet 24 in the width direction D2. In the negative electrode sheet 24, BOB ions contained in the electrolyte that penetrates from the ends of the negative electrode sheet 24 react excessively with Na ions derived from the material in the central part of the negative electrode sheet 24, resulting in a larger film thickness in the central part of the negative electrode sheet 24. Therefore, the resistance in the central part of the negative electrode sheet 24 is higher than in the ends, and Li is more likely to precipitate. It is necessary to homogenize this resistance distribution.

[0036] [Relationship between orientation and specific surface area] Figure 4 shows the difference in orientation of the negative electrode active material contained in the negative electrode composite layer 26 coated on the negative electrode current collector 25. The figure on the left shows a state with low orientation of the negative electrode active material. In this state of low orientation, the negative electrode active material is not aligned and is difficult to crush even when rolled. The figure on the right shows a state with high orientation of the negative electrode active material. In this state of high orientation, the negative electrode active material is aligned and is easily crushed when rolled. Therefore, by increasing the orientation, a negative electrode sheet 24 that is easily crushed can be made. The orientation of the negative electrode active material can be increased by applying a magnetic field.

[0037] As shown in Figure 5, the Δdensity, which is the change in density of the anode composite layer 26 before and after rolling, and the Δspecific surface area, which is the change in the specific surface area of ​​the anode composite layer 26 before and after rolling, are proportional. As the Δdensity increases, the Δspecific surface area also increases. At the same Δdensity, a higher orientation results in a smaller Δspecific surface area. In other words, the damage to the anode active material, which is a factor in the change in specific surface area, decreases with higher orientation, so the Δspecific surface area at the same Δdensity becomes smaller.

[0038] [Orientation calculation process] As shown in Figure 6, first, the relationship between the resistance of the negative electrode sheet 24 and the specific surface area of ​​the negative electrode composite layer 26 is obtained (step S1). That is, negative electrode sheets 24 are made using negative electrode active materials with different specific surface areas, and the resistance distribution of the negative electrode sheets 24 containing negative electrode active materials with different specific surface areas is measured. As shown in Figure 7, as the specific surface area of ​​the negative electrode composite layer 26 increases, the resistance ratio of the negative electrode sheet 24 decreases.

[0039] Next, the difference in resistance between the central part and the edges of the negative electrode sheet 24 is calculated (step S2). As shown in Figure 8, the resistance distribution on the imaginary line connecting both ends of the negative electrode sheet 24 is mountain-shaped with a convex center, and is symmetrical with respect to the center. The difference in resistance A is calculated by subtracting the resistance value of the edges included in the edge region from the resistance value of the central part included in the central region. The resistance value of the edge region is taken as the value of the part where the resistance change is small.

[0040] Next, the difference in specific surface area between the center and the edges of the negative electrode sheet 24 is calculated (step S3). As shown in Figure 9, the difference B in specific surface area between the center and the edges of the negative electrode sheet 24 is calculated from the relationship between resistance and specific surface area obtained in step S1 and the difference A in resistance values ​​in step S2. In the rolling process, the difference in specific surface area Δ, which is the change in specific surface area between the edges and the center of the negative electrode sheet 24, should be equal to the above difference B in specific surface area.

[0041] Next, the Δ specific surface area of ​​the negative electrode sheet 24 is measured (step S4). That is, negative electrode sheets 24 with different orientations of the negative electrode active material are fabricated by applying a magnetic field, and the Δ specific surface area is measured before and after rolling when rolled to the target density. As shown in Figure 10, the orientation of the negative electrode composite layer 26 and the Δ specific surface area of ​​the negative electrode composite layer 26 are proportional, and as the orientation of the negative electrode composite layer 26 increases, the Δ specific surface area of ​​the negative electrode composite layer 26 also increases. Δ specific surface area = f(orientation)···(1).

[0042] Next, the Δ specific surface area corresponding to the central part of the negative electrode sheet 24 is calculated (step S5). That is, the Δ specific surface area before and after rolling, when the orientation of the negative electrode active material is not increased, is calculated from equation (1) in step S4 and the orientation value when no magnetic field is applied. This corresponds to the Δ specific surface area of ​​the central part of the negative electrode sheet 24.

[0043] Next, the Δ-specific surface area corresponding to the edge of the negative electrode sheet 24 is calculated (step S6). That is, the Δ-specific surface area of ​​the edge of the negative electrode sheet 24 is calculated using equation (2) from the difference B of the Δ-specific surface area calculated in step S3 and the Δ-specific surface area of ​​the central part of the negative electrode sheet 24 calculated in step S5. Δ-specific surface area difference = Δ-specific surface area of ​​the central part - Δ-specific surface area of ​​the edge ... (2)

[0044] Next, the target value of orientation is calculated (step S7). That is, the value of orientation is calculated for the Δ specific surface area of ​​the negative electrode sheet 24 in step S4 shown in Figure 10, corresponding to the Δ specific surface area of ​​the edge of the negative electrode sheet 24 calculated in step S6.

[0045] The viscosity of the paste used when coating the negative electrode composite layer 26 onto the negative electrode current collector 25 is adjusted so that the orientation is as calculated in the orientation calculation process described above. In addition, the magnetic flux density of the magnetic field applied to the end region after coating the negative electrode current collector 25 with the negative electrode composite layer 26 is adjusted. Therefore, by increasing the orientation of the negative electrode composite layer 26 in the end region, the Δ specific surface area at the same Δ density can be reduced only in the end region. In other words, to make the resistance distribution of the negative electrode sheet 24 uniform, it is effective to reduce the reactivity by making the specific surface area of ​​the ends lower than the specific surface area of ​​the central part.

[0046] Next, the effects of this embodiment will be described. (1-1) Increasing the orientation of the negative electrode active material reduces the difference in specific surface area before and after rolling. Therefore, the specific surface area can be changed by adjusting the orientation of the negative electrode active material. By using this to adjust the orientation of the negative electrode active material, the resistance distribution in the negative electrode sheet 24 can be made uniform.

[0047] (1-2) Applying a magnetic field to the negative electrode sheet 24 can increase the orientation of the negative electrode active material. Therefore, by adjusting the magnetic field, the desired orientation can be achieved to obtain the desired BET specific surface area.

[0048] (Other embodiments) The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0049] In the above embodiment, the region was divided into a central region and an edge region, and the orientation of the edge region was set. However, the edge region may be divided into multiple parts, and the orientation may be set accordingly. Alternatively, the orientation of each position relative to the center can be set. That is, the difference in specific surface area of ​​each position relative to the center is calculated, and the orientation of each position is calculated from the Δ specific surface area. Then, different magnetic fields are applied to each position to achieve the calculated orientation.

[0050] In the above embodiment, the paste viscosity when coating the negative electrode composite layer 26 onto the negative electrode current collector 25 was adjusted so that the orientation was as calculated in the orientation calculation process. However, the paste viscosity when coating the negative electrode composite layer 26 onto the negative electrode current collector 25 may not be adjusted, and only the magnetic field applied to the negative electrode sheet 24 after coating may be adjusted so that the orientation is as calculated in the orientation calculation process.

[0051] In the above embodiment, LiBOB was added as a lithium salt to the non-aqueous electrolyte. However, the lithium salt is not limited to LiBOB. In the above embodiment, the electrode body 20 was formed by winding a laminate in which a positive electrode sheet 21 and a negative electrode sheet 24 were stacked with a separator 27 in between. However, the electrode body may also be formed by stacking multiple positive electrode sheets 21 and multiple negative electrode sheets 24 alternately with a separator 27 in between.

[0052] The lithium-ion secondary battery 10 may be installed in automated transport machines, special vehicles for cargo handling, electric vehicles, hybrid vehicles, etc., as well as in computers and other electronic devices, or it may constitute a system other than those mentioned above. For example, it may be installed in mobile objects such as ships and aircraft, or it may be part of a power supply system that supplies electricity from a power plant to buildings and homes where the secondary battery is installed via a substation or the like. [Explanation of symbols]

[0053] 10…Lithium-ion rechargeable battery 11…Battery case 12... Lid 13A…Positive external terminal 13B…Negative external terminal 14A... Positive electrode current collector 14B... Negative electrode current collector 20...Electrode body 20A... Positive electrode current collector 20B... Negative electrode current collector 21…Positive electrode sheet 22...Positive electrode current collector 22A...Unpainted area on the positive electrode side 23…Positive electrode composite layer 24... Negative electrode sheet 25...Negative electrode current collector 25A...Unpainted area on the negative electrode side 26...Negative electrode composite material layer 27... Separator

Claims

1. A method for manufacturing a non-aqueous secondary battery comprising an electrode body in which a positive electrode sheet and a negative electrode sheet are stacked with a separator in between, and a non-aqueous electrolyte containing a film-forming agent containing a lithium salt, A coating step for manufacturing the negative electrode sheet, comprising coating a negative electrode composite layer containing a negative electrode active material and an additive containing a sodium salt onto a negative electrode substrate, The process includes a rolling step of rolling the negative electrode sheet coated with the negative electrode composite layer, In the coating process, the orientation of the negative electrode active material is adjusted based on the relationship between the difference in BET specific surface area of ​​the negative electrode active material before and after rolling and the orientation of the negative electrode active material, so that the resistance distribution of the negative electrode sheet after rolling becomes uniform. A method for manufacturing a non-aqueous secondary battery.

2. A method for manufacturing a non-aqueous secondary battery comprising an electrode body in which a positive electrode sheet and a negative electrode sheet are stacked with a separator in between, and a non-aqueous electrolyte containing a film-forming agent containing a lithium salt, A coating step for manufacturing the negative electrode sheet, comprising coating a negative electrode composite layer containing a negative electrode active material and an additive containing a sodium salt onto a negative electrode substrate, The process includes a rolling step of rolling the negative electrode sheet coated with the negative electrode composite layer, The negative electrode composite layer comprises end regions including both ends of the negative electrode sheet into which the non-aqueous electrolyte permeates from both ends, and a central region located between the two end regions. In the coating process, the orientation of the negative electrode active material in the central region and the end region is adjusted based on the relationship between the BET specific surface area of ​​the negative electrode active material and the orientation of the negative electrode active material, such that the BET specific surface area of ​​the negative electrode active material in the central region after rolling is greater than the BET specific surface area of ​​the negative electrode active material in the end region. A method for manufacturing a non-aqueous secondary battery.

3. The coating process includes applying the negative electrode composite layer to the negative electrode substrate, and then applying a magnetic field to achieve an orientation that results in a desired BET specific surface area. A method for manufacturing a non-aqueous secondary battery according to claim 1 or 2.

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