Nonaqueous electrolyte secondary battery and manufacturing method

Abstract

The present disclosure pertains to a non-aqueous electrolyte secondary battery in which a positive electrode active material layer contains a positive electrode active material represented by formula (1), and in which S represents the specific surface area of a negative electrode active material layer, M1 (mass%) represents the average boron content of boron contained in the negative electrode active material layer, and M2 (mass%) represents the boron content in the central portion of the negative electrode active material layer, M represents the specific surface area of the negative electrode active material layer, and M represents the specific surface area of the negative electrode active material layer. (a) M1 / S < = 0.1 and (b) M2 > = 0.05 are satisfied.

Description

Technical Field

[0001] The present disclosure relates to a non-aqueous electrolyte secondary battery, and further relates to a method for manufacturing a non-aqueous electrolyte secondary battery. Background Art

[0002] In Japanese Patent Application Laid-Open No. 2022-112207, a non-aqueous electrolyte secondary battery using a lithium composite oxide having a high nickel content for a positive electrode active material layer is proposed. Summary of the Invention

[0003] When a lithium composite oxide having a high nickel content is used for the positive electrode active material layer, it becomes possible to increase the capacity of a non-aqueous electrolyte secondary battery (hereinafter also referred to as a battery). However, when a conductive foreign substance is mixed into the battery, it is known that due to the following steps (1) to (3), there is a tendency for the reaction heat between the positive electrode plate and the electrolyte to be easily generated.

[0004] (1) A current (short-circuit current) flows through the conductive foreign substance, generating heat.

[0005] (2) Along with the heat generation in the above (1), the negative electrode plate reacts with the electrolyte to generate heat.

[0006] (3) The positive electrode reacts with the electrolyte to generate heat.

[0007] In addition, when the battery size is relatively large, the short-circuit current increases, and as a result, there is a tendency for the reaction heat between the positive electrode plate and the electrolyte to be easily generated.

[0008] In order to suppress the reaction heat between the positive electrode plate and the electrolyte, it is required to improve the fusing performance of cutting off the short-circuit current by the melting and spreading of the positive electrode substrate (metal foil, etc.). The shorter the time from the occurrence of a short circuit to the occurrence of fusing, the better the fusing performance. In terms of fusing properties, it is easy to improve if a film generated by the electrolyte is formed on the surface of the positive electrode active material, but the internal resistance of the battery increases, and as a result, the output characteristics tend to be easily reduced.

[0009] An object of the present disclosure is to provide a non-aqueous electrolyte secondary battery and a method for manufacturing a non-aqueous electrolyte secondary battery that suppress an increase in internal resistance and have good fusing properties.

[0010] The present invention provides the following non-aqueous electrolyte secondary battery and method for manufacturing a non-aqueous electrolyte secondary battery.

[0011] [1] A non-aqueous electrolyte secondary battery, which includes an electrode body and an electrolyte,

[0012] The above electrode body includes a positive electrode plate and a negative electrode plate,

[0013] The above positive electrode plate includes a positive electrode active material layer,

[0014] The above-mentioned negative electrode plate includes a negative electrode active material layer,

[0015] The above-mentioned positive electrode active material layer includes a positive electrode active material represented by formula (1):

[0016] Li (1+x) Ni y Ti z Me (1-y-z) O 2

[0017] In formula (1), Me includes two or more selected from Mn, Co, and Al, satisfying the relationships of 0 < x < 0.1, 0.8 < y < 0.85, and 0 ≤ z < 0.03.

[0018] The above-mentioned negative electrode active material layer includes a negative electrode active material.

[0019] When the specific surface area of the above-mentioned negative electrode active material layer is set as S, the average boron content of boron contained in the above-mentioned negative electrode active material layer is set as M1 (mass %), and the boron content of the central part of the above-mentioned negative electrode active material layer is set as M2 (mass %), the following relational expression is satisfied:

[0020] (a) M1 / S ≤ 0.1

[0021] (b) M2 ≥ 0.05.

[0022] [2] The non-aqueous electrolyte secondary battery according to [1], wherein the total relative area of the above-mentioned electrode body is 3 m 2 or more.

[0023] The length of the short side of the shape of the above-mentioned negative electrode active material layer of one continuous negative electrode plate in a plan view is 80 mm or more and 400 mm or less.

[0024] [3] The non-aqueous electrolyte secondary battery according to [1], which further satisfies the following relational expression:

[0025] (c) 2 ≤ S ≤ 4.

[0026] [4] The non-aqueous electrolyte secondary battery according to [1], wherein the graphite content in the above-mentioned negative electrode active material is 99 mass % or more.

[0027] [5] A method for manufacturing a non-aqueous electrolyte secondary battery, which includes:

[0028] The step of inserting an electrode body into an outer package, injecting

[0029] the electrolyte solution, and

[0030] the activation step.

[0031] The above electrode body includes a positive electrode plate and a negative electrode plate.

[0032] The above positive electrode plate includes a positive electrode active material layer.

[0033] The above negative electrode plate includes a negative electrode active material layer, and the above positive electrode active material layer includes a positive electrode active material represented by formula (1):

[0034] Li (1+x) Ni y Ti z Me (1-y-z) O 2

[0035] In formula (1), Me includes two or more selected from Mn, Co, and Al, and satisfies the relationship of 0 < x < 0.1, 0.8 < y < 0.85, and 0 ≤ z < 0.03.

[0036] The above negative electrode active material layer includes a negative electrode active material.

[0037] When the specific surface area of the above negative electrode active material layer is set as S, the average boron content of boron contained in the above negative electrode active material layer is set as M1 (mass %), and the boron content of the central part of the above negative electrode active material layer is set as M2 (mass %), the following relational expression is satisfied:

[0038] (a) M1 / S ≤ 0.1

[0039] (b) M2 ≥ 0.05.

[0040] The above and other objects, features, aspects, and advantages of the present invention will become apparent from the following detailed description related to the present invention understood in association with the drawings. Description of the Drawings

[0041] Figure 1 It is a schematic diagram showing an example of the configuration of the battery in the present embodiment.

[0042] Figure 2 It is a schematic diagram showing an example of the configuration of the electrode body in the present embodiment.

[0043] Figure 3 It is a schematic flowchart of the manufacturing method of the battery in the present embodiment.

[0044] Figure 4 It is a schematic diagram showing the configuration of the electrode body in the examples.

[0045] Figure 5 It is a schematic diagram for explaining the part for measuring the boron content in the examples. Detailed Embodiments

[0046] Hereinafter, while referring to the attachedFigure 1 The embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. In all the following drawings, in order to make each component easy to understand, the scale is appropriately adjusted for representation, and the scale of each component shown in the drawings is not necessarily the same as that of the actual component. In the description of each of the following embodiments, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

[0047] <Non-aqueous electrolyte secondary battery>

[0048] Figure 1 FIG. is a schematic diagram showing an example of the configuration of the battery in the present embodiment.

[0049] The battery 100 can be used in any application. Regarding the battery 100, for example, in an electric vehicle, it can be used as a main power source or a power assist power source. By connecting a plurality of batteries 100, a battery module or a battery pack can be formed.

[0050] The battery 100 includes an outer package 90. The outer package 90 is square (flat rectangular parallelepiped shape). However, the square is an example. The outer package 90 can have any shape. The outer package 90 can be, for example, cylindrical or pouch-shaped. The outer package 90 can be made of, for example, an Al alloy. The outer package 90 houses the electrode body 50 and an electrolyte (not shown). The outer package 90 can include, for example, a sealing plate 91 and an outer can 92. The sealing plate 91 closes the opening of the outer can 92. For example, laser welding can be used to join the sealing plate 91 and the outer can 92.

[0051] On the sealing plate 91, a positive electrode terminal 81 and a negative electrode terminal 82 are provided. On the sealing plate 91, an injection port and a gas discharge valve can be further provided. The electrolyte can be injected into the interior of the outer package 90 through the injection port. The electrode body 50 is connected to the positive electrode terminal 81 through a positive electrode current collector member 71. The positive electrode current collector member 71 can be, for example, an Al plate or the like. The electrode body 50 is connected to the negative electrode terminal 82 through a negative electrode current collector member 72. The negative electrode current collector member 72 can be, for example, a Cu plate or the like.

[0052] Figure 2It is a schematic diagram showing an example of the configuration of the electrode body in this embodiment. The electrode body 50 is of a wound type. The electrode body 50 includes a positive electrode plate 10, a separator 30, and a negative electrode plate 20. That is, the battery 100 includes a positive electrode plate 10, a negative electrode plate 20, and an electrolyte. The positive electrode plate 10, the separator 30, and the negative electrode plate 20 are all strip-shaped sheets. The electrode body 50 may include multiple separators 30. The electrode body 50 is formed by sequentially laminating and winding the positive electrode plate 10, the separator 30, and the negative electrode plate 20 into a spiral shape. One of the positive electrode plate 10 or the negative electrode plate 20 may be clamped by the separator 30. Both the positive electrode plate 10 and the negative electrode plate 20 may be clamped by the separator 30. The electrode body 50 may be formed into a flat shape after winding. Note that the wound type is an example. The electrode body 50 may be, for example, a laminated (stacked) type.

[0053] The total relative area of the electrode body 50 may be, for example, 3 m 2 The above. Regarding the electrode body 50, as Figure 2 shown, by being in a state where the positive electrode plate 10 and the negative electrode plate 20 are laminated with each other via the separator 30, portions that are opposite to the negative electrode plate 20 on one or both sides of the positive electrode plate 10, and portions that are opposite to the positive electrode plate 10 on one or both sides of the negative electrode plate 20 are formed. The total relative area of the electrode body 50 refers to the sum of the area of the portion of the positive electrode plate 10 that is opposite to the negative electrode plate 20 and the area of the portion of the negative electrode plate 20 that is opposite to the positive electrode plate 10. The total relative area of the electrode body 50 may be, for example, 3 m 2 or more and 10 m 2 or less.

[0054] (Positive Electrode Plate)

[0055] The positive electrode plate 10 includes a positive electrode substrate 11 and a positive electrode active material layer 12. The positive electrode substrate 11 is a conductive sheet. The positive electrode substrate 11 may be, for example, an Al alloy foil or the like. The positive electrode substrate 11 may have a thickness of, for example, 10 μm to 30 μm. The positive electrode active material layer 12 is disposed on the surface of the positive electrode substrate 11. The positive electrode active material layer 12 may be disposed, for example, only on one side of the positive electrode substrate 11. The positive electrode active material layer 12 may also be disposed on both the front and back surfaces of the positive electrode substrate 11. In the width direction of the positive electrode plate 10 ( Figure 2 the X-axis direction), the positive electrode substrate 11 may be exposed at one end. A positive electrode current collector member 71 may be joined to the exposed portion of the positive electrode substrate 11.

[0056] For example, an intermediate layer (not shown) may be formed between the positive electrode active material layer 12 and the positive electrode substrate 11. In this embodiment, in the case of having an intermediate layer, it is also regarded as disposing the positive electrode active material layer 12 on the surface of the positive electrode substrate 11. The intermediate layer may be thinner than the positive electrode active material layer 12. The intermediate layer may have a thickness of, for example, 0.1 μm to 10 μm. The intermediate layer may include, for example, a conductive material, an insulating material, and the like.

[0057] (Positive Electrode Active Material Layer)

[0058] The positive electrode active material layer 12 contains a positive electrode active material. The positive electrode active material contains the following formula (1):

[0059] Li (1+x) Ni y Ti z Me (1-y-z) O 2

[0060] [In formula (1),

[0061] Me contains two or more selected from Mn, Co and Al,

[0062] Satisfying the relationship 0<x<0.1, 0.8<y<0.85, 0≤z<0.03]

[0063] Represents a layered metal oxide.

[0064] The layered metal oxide represented by the formula (1) preferably satisfies the following relationships: 0<x<0.2, 0.8<y<0.84, and 0.01<z<0.03, from the viewpoint of the melting property.

[0065] The layered metal oxide represented by formula (1) may include at least one selected from Zr, B, Mg, Fe, Cu, Zn, Sn, Na, K, Ba, Sr, Ca, W, Mo, Nb, Si, V, Cr and Ge.

[0066] The positive electrode active material is a particle group. The particle group can include a first positive electrode active material particle group and a second positive electrode active material particle group. The first positive electrode active material particle group is composed of a plurality of first positive electrode active material particles. The second positive electrode active material particle group is composed of a plurality of second positive electrode active material particles. The first positive electrode active material particles and the second positive electrode active material particles can have any shape. The first positive electrode active material particles and the second positive electrode active material particles can be, for example, spherical, columnar, blocky, etc.

[0067] The plurality of first positive electrode active material particles may have an average particle size (D50) of, for example, 10 μm to 20 μm. The plurality of second positive electrode active material particles may have an average particle size (D50) of, for example, 0.5 μm to 9 μm. The average particle size (D50) in this specification is the particle size at which the accumulation of the frequency from the smaller particle size in the volume-based particle size distribution becomes 50%. The volume-based particle size distribution can be measured by a laser diffraction particle size distribution measuring device.

[0068] The first positive electrode active material particles and the second positive electrode active material particles independently contain a positive electrode active material represented by Formula (1). The first positive electrode active material particles and the second positive electrode active material particles can independently have any crystal structure. For example, the first positive electrode active material particles and the second positive electrode active material particles can have a layered structure, a spinel structure, an olivine structure, etc. The first positive electrode active material particles and the second positive electrode active material particles can have substantially the same chemical composition. The first positive electrode active material particles and the second positive electrode active material particles can have different chemical compositions from each other.

[0069] Regarding the positive electrode active material layer 12, as long as it contains a positive electrode active material, additional components can be further contained. In addition to the positive electrode active material, the positive electrode active material layer 12 can contain, for example, a conductive material and a binder. The conductive material can contain any components. For example, the conductive material can contain at least one selected from carbon black, graphite, vapor-grown carbon fiber (VGCF), carbon nanotube (CNT), and graphene flakes. The compounding amount of the conductive material can be, for example, 0.1 parts by mass to 10 parts by mass with respect to 100 parts by mass of the positive electrode active material. The binder can contain any components. For example, the binder can contain at least one selected from polyvinylidene fluoride (PVdF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), polytetrafluoroethylene (PTFE), and polyacrylic acid (PAA). The compounding amount of the binder can be, for example, 0.1 parts by mass to 10 parts by mass with respect to 100 parts by mass of the positive electrode active material. Regarding the positive electrode active material layer 12, for example, by mass fraction, it can contain 80% to 99% of the positive electrode active material, 0.1% to 10% of the conductive material, and the balance of the binder.

[0070] The positive electrode active material layer 12 can have a thickness of, for example, 10 μm to 200 μm. The positive electrode active material layer 12 can have a thickness of, for example, 50 μm to 150 μm. The positive electrode active material layer 12 can have a thickness of, for example, 50 μm to 100 μm.

[0071] The positive electrode active material layer 12 can have a high density. The positive electrode active material layer 12 can have, for example, a density of 3.3 g / cm 3 to 3.9 g / cm 3 The positive electrode active material layer 12 can have, for example, a density of 3.4 g / cm 3 to 3.7 g / cm 3 The positive electrode active material layer 12 can have, for example, a density of 3.4 g / cm 3 to 3.6 g / cm 3 The density of the active material layer in this specification represents the apparent density.

[0072] Regarding the positive electrode plate 10, the positive electrode active material layer 12 is formed by coating the positive electrode paste on the surface of the positive electrode substrate 11. Then, after manufacturing the green sheet (green film) by calendering the positive electrode active material layer 12 and the positive electrode substrate 11, it is manufactured by cutting to a specified planar size according to the specifications of the battery 100. The positive electrode paste is prepared by mixing the positive electrode active material and additional components.

[0073] (Negative electrode plate)

[0074] The negative electrode plate 20 may include, for example, a negative electrode substrate 21 and a negative electrode active material layer 22. The negative electrode substrate 21 is a conductive sheet. The negative electrode substrate 21 may be, for example, a Cu alloy foil or the like. The negative electrode substrate 21 may have a thickness of, for example, 5 μm to 30 μm. The negative electrode active material layer 22 may be disposed on the surface of the negative electrode substrate 21. The negative electrode active material layer 22 may be disposed only on, for example, one side of the negative electrode substrate 21. The negative electrode active material layer 22 may also be disposed on, for example, both the front and back surfaces of the negative electrode substrate 21. In the width direction of the negative electrode plate 20 ( Figure 2 the X-axis direction), the negative electrode substrate 21 may be exposed at one end. The negative electrode current collector member 72 may be joined to the exposed portion of the negative electrode substrate 21.

[0075] (Negative electrode active material layer)

[0076] The negative electrode active material layer 22 contains a negative electrode active material. The negative electrode active material may contain any components. The negative electrode active material may contain, for example, at least one selected from graphite, soft carbon, hard carbon, silicon, silicon oxide, silicon-based alloy, tin, tin oxide, tin-based alloy, and lithium titanium composite oxide. The graphite may be natural graphite or artificial graphite.

[0077] The negative electrode active material layer 22 further contains boron (B). When the specific surface area of the negative electrode active material layer 22 is set as S, the average boron content of boron contained in the negative electrode active material layer 22 is set as M1 (mass %), and the boron content of the central portion of the negative electrode active material layer 22 is set as M2 (mass %), the following relational expressions are satisfied:

[0078] (a) M1 / S ≤ 0.1

[0079] (b) M2 ≥ 0.05.

[0080] The above central portion is the central portion in the plane of the negative electrode plate when viewed from the top-down direction.

[0081] When viewing the electrode body 50 in the planar direction of the electrode plate, with respect to the central portion in the electrode plate plane, the electrolyte tends to be difficult to penetrate. For example, in a square-shaped battery, since the electrolyte is injected from a surface other than the planar direction of the electrode plate constituting the electrode body (any one of the four short side surfaces, generally the liquid injection hole on the lid side), the electrolyte tends to be difficult to penetrate the central portion of the electrode plate in the electrode plate plane. As a result, the amount of the film formed by the electrolyte on the surface of the active material becomes less, and the fusibility tends to be easily reduced. In addition, if one wants to increase the amount of the film at the central portion of the electrode body 50, the amount of the film becomes excessive, and as a result, there is a tendency for the internal resistance of the battery to easily increase. However, by satisfying the relational expressions (a) and (b), a battery achieving a balance between resistance and fusibility can be provided. With respect to the central portion of the negative electrode plate, it can be a region with a radius of 20 mm from the center of the negative electrode plate plane when viewing the electrode body 50 in the Y-axis direction.

[0082] As a method for satisfying the relational expressions (a) and (b), for example, selection of the type of additives contained in the electrolyte and adjustment of the concentration, adjustment of the specific surface area, thickness, and density of the negative electrode active material layer 22, selection of the type of negative electrode active material and adjustment of the content, etc. can be cited. For the battery 100, after the activation process described later, the relational expressions (a) and (b) can be satisfied.

[0083] M1 can be, for example, 0.1 to 0.5% by mass, preferably 0.15 to 3% by mass. M2 can be, for example, 0.05 to 0.3% by mass, preferably 0.09 to 0.2% by mass. M1 and M2 are measured according to the method described in the column of the following examples. For M2, in the case of a wound electrode body, it can be the boron content in the central portion of the negative electrode active material layer that is the outermost layer. For M1, in the case of a wound electrode body, it can be the average value of the boron content at 9 points in the plane of the negative electrode active material layer that is the outermost layer. In addition, for M2, in the case of a stacked electrode body, it can be the boron content in the central portion of the outermost negative electrode active material layer. For M1, in the case of a stacked electrode body, it can be the average value of the boron content at 9 points in the plane of the outermost negative electrode active material layer.

[0084] The negative electrode active material layer 22 further satisfies the following relational expression:

[0085] (c) 2 ≤ S ≤ 4.

[0086] The specific surface area S of the negative electrode active material layer 22 is measured according to the method described in the column of the following examples.

[0087] Regarding the negative electrode active material layer 22, in addition to the negative electrode active material, as other components, for example, a binder or the like may be further included. For example, in terms of mass fraction, the negative electrode active material layer 22 may contain 95% to 99.5% of the negative electrode active material and the balance of the binder. The binder may contain any components. The binder may contain, for example, at least one selected from carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR). When the negative electrode active material layer 22 contains graphite, the graphite content in the negative electrode active material is preferably 99% by mass or more. The specific surface area of the negative electrode active material may be, for example, 0.5 to 5 m 2 / g.

[0088] The negative electrode active material layer 22 may have a thickness of, for example, 10 μm to 200 μm.

[0089] The negative electrode active material layer 22 may have a high density. The negative electrode active material layer 22 may have a density of, for example, 1.0 g / cm 3 to 2.0 g / cm 3 The negative electrode active material layer 22 may have a density of, for example, 1.2 g / cm 3 to 1.7 g / cm 3 The negative electrode active material layer 22 may have a density of, for example, 1.3 g / cm 3 to 1.6 g / cm 3 The negative electrode active material layer 22 may have a density of, for example, 1.3 g / cm

[0090] Regarding the negative electrode plate 20, the negative electrode active material layer 22 is formed by coating a negative electrode paste on the surface of the negative electrode substrate 21. Then, after manufacturing a green sheet by calendering the negative electrode active material layer 22 and the negative electrode substrate 21, it is manufactured by cutting to a specified planar size according to the specifications of the battery 100. The negative electrode paste is prepared by mixing the negative electrode active material and other components.

[0091] Regarding the shape of a continuous negative electrode active material layer in the negative electrode plate 20 as viewed from above, it may be, for example, rectangular. The length of the short side of the shape of a continuous negative electrode active material layer in the negative electrode plate 20 as viewed from above ( Figure 2 in which the length of L) may be, for example, 80 mm or more and 400 mm or less.

[0092] (Spacer)

[0093] At least a part of the spacer 30 is interposed between the positive electrode plate 10 and the negative electrode plate 20. The spacer 30 separates the positive electrode plate 10 and the negative electrode plate 20. The spacer 30 may have a thickness of, for example, 10 μm to 30 μm.

[0094] The spacer 30 is a porous sheet. The spacer 30 allows the electrolyte to pass through. The spacer 30 may have an air permeability of, for example, 100 s / 100 mL to 400 s / 100 mL. The "air permeability" in this specification means the "Air Resistance" specified in "JIS P 8117:2009". The air permeability is measured by the Gurley test method.

[0095] The spacer 30 is electrically insulating. The spacer 30 may contain, for example, a polyolefin resin or the like. The spacer 30 may be substantially composed of, for example, a polyolefin resin. The polyolefin resin may contain, for example, at least one selected from polyethylene (PE) and polypropylene (PP). The spacer 30 may have, for example, a single-layer structure. The spacer 30 may be substantially composed of, for example, a PE layer. The spacer 30 may have, for example, a multilayer structure. The spacer 30 may be formed by laminating, for example, a PP layer, a PE layer, and a PP layer in sequence. On the surface of the spacer 30, a heat-resistant layer or the like may be formed.

[0096] (Electrolyte)

[0097] The electrolyte contains a solvent and a supporting electrolyte. The solvent is aprotic. The solvent may contain any components. The solvent may contain, for example, at least one selected from ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), 1,2-dimethoxyethane (DME), methyl formate (MF), methyl acetate (MA), methyl propionate (MP), and γ-butyrolactone (GBL).

[0098] The supporting electrolyte is dissolved in the solvent. The supporting electrolyte may contain, for example, at least one selected from LiPF 6 , LiBF 4 and LiN(FSO 2 ) 2 The supporting electrolyte may have a molar concentration of, for example, 0.5 mol / L to 2.0 mol / L. The supporting electrolyte may have a molar concentration of, for example, 0.8 mol / L to 1.2 mol / L.

[0099] The electrolyte may further contain any additives. For example, when the electrolyte is expressed in mass fraction, it may contain 0.01% to 5% of additives. The additives may contain, for example, at least one selected from vinylene carbonate (VC), lithium difluorophosphate (LiPO 2 F 2 ), lithium fluorosulfonate (FSO 3 Li) and lithium bis(oxalato)borate (LiBOB). The electrolyte preferably contains LiBOB. When the electrolyte contains LiBOB, the content of LiBOB in the electrolyte may be, for example, 0.1 to 1.5 mass%.

[0100] <Method for manufacturing a battery>

[0101] The method for manufacturing the battery in the present embodiment is as Figure 3 shown, and includes a step (A) of inserting an electrode body into an outer package, a step (B) of injecting an electrolytic solution, and an activation step (C).

[0102] In the step (A) of inserting the electrode body into the outer package, the electrode body 50 is accommodated in the outer package 90. The electrode body 50 can be connected to the positive terminal 81 through the positive current collector member 71. The electrode body 50 can be connected to the negative terminal 82 through, for example, the negative current collector member 72.

[0103] In the step (B) of injecting the electrolytic solution, the electrolytic solution is injected into the outer package 90. The electrolytic solution is impregnated into the electrode body 50. After the injection of the electrolytic solution, the outer package 90 is sealed.

[0104] In the activation step (C), the battery 100 is activated. For example, the battery 100 is charged in a constant current-constant voltage (CC-CV) manner, and after a specified time, it is discharged in a constant current (CC-CV) manner. More specifically, in a temperature environment of 25 °C, through a current of 0.2 mA / cm 2 , it is charged in a constant current manner until the positive electrode potential reaches 4.30 V (vs. Li + / Li), and then, it is charged in a constant voltage manner until the current reaches 0.04 mA / cm 2 . Then, after a 10-minute stop, through a current of 0.2 mA / cm 2 , it is discharged in a constant current manner until the positive electrode potential reaches 2.5 V (vs. Li + / Li).

[0105] From the above, the battery 100 is manufactured. Regarding the manufactured battery 100, by satisfying the relational expressions (a) and (b) as described above, the increase in the internal resistance is suppressed, and good fusing properties are provided.

[0106] Examples

[0107] Hereinafter, the present invention will be described in more detail by way of examples. In the examples, "%" and "parts" are mass % and mass parts unless otherwise specified.

[0108] <Example 1>

[0109] (Manufacture of positive electrode plate)

[0110] By using a lithium nickel composite oxide (Li 1.03 Ni 0.82 Co 0.05 Mn 0.11 O2 ) are mixed with large particles and small particles to prepare a mixed powder of positive electrode active material. The mixing ratio is "large particles / small particles = 6 / 4 (mass ratio)". The D50 of large particles is 17μm, and the D50 of small particles is 4μm. The positive electrode slurry is prepared by mixing 97.6 parts by mass of the mixed powder, 1.5 parts by mass of a conductive material (carbon black), 0.9 parts by mass of a binder (PVdF) and a specified amount of a dispersion medium (N-methyl-2-pyrrolidone). The positive electrode slurry is applied on the surface of the positive electrode substrate (Al foil) at 350 (g / m 2 ) coating amount, and drying to form a positive electrode active material layer. The positive electrode active material layer is compressed by a calender. Thus, a positive electrode original sheet with a positive electrode active material layer density of 3.5 (g / cc) is manufactured. The positive electrode original sheet is cut into a specified size to manufacture a positive electrode plate. The electrode terminal (Al thin plate) is joined to the positive electrode plate.

[0111] (Manufacturing of negative electrode plates)

[0112] By mixing 98 parts by mass of the negative electrode active material (graphite, D50 = 17 μm, specific surface area = 1.2 m 2 / g), 1 part by mass of CMC, 1 part by mass of SBR and a predetermined amount of dispersion medium (water) were mixed to prepare negative electrode slurry. The negative electrode slurry was applied to the surface of the negative electrode substrate (Cu foil) at a temperature of 225 (g / m 2 ) and dried to form a specific surface area S of 2 (m 2 / g) of negative electrode active material layer. The negative electrode active material layer is compressed by a calender. Thus, a negative electrode original sheet with a negative electrode active material layer density of 1.5 (g / cc) is manufactured. The negative electrode original sheet is cut into a specified size to manufacture a negative electrode plate. The electrode terminal (Ni thin plate) is joined to the negative electrode plate.

[0113] (Assembly)

[0114] As a separator, a porous sheet made of polyolefin is prepared. The positive plate, the separator and the negative plate are stacked in such a manner that the separator is interposed between the positive plate and the negative plate. By winding them, a wound electrode body is formed. As an outer body, a bag made of Al laminated film is prepared. The electrode body is accommodated in the outer body.

[0115] (Injection of electrolyte)

[0116] Prepare an electrolyte. The electrolyte contains the following components. Inject the electrolyte into the outer body in an amount of 2 (g / Ah). Seal the outer body. In the above manner, a test battery is manufactured.

[0117] Solvent: EC / EMC=3 / 7 (volume ratio)

[0118] Supporting electrolyte: LiPF 6(1 mol / L)

[0119] Additive: LiBOB (mass fraction is 0.5%)

[0120] (Activation)

[0121] At a temperature of 25 °C, initial charge and discharge are carried out. With a current of 0.2 mA / cm 2 , the test battery is charged in a constant current manner until the positive electrode potential reaches 4.30 V (vs. Li + / Li). Then, the test battery is charged in a constant voltage manner until the current reaches 0.04 mA / cm 2 . After a 10-minute pause, with a current of 0.2 mA / cm 2 , the test battery is discharged in a constant current manner until the positive electrode potential reaches 2.5 V (vs. Li + / Li). In this example, in all test batteries, the initial single-electrode charging capacity is 80 Ah / m 2 at the positive electrode and 85 Ah / m 2 at the negative electrode, and the initial single-electrode discharge capacity is 73.6 Ah / m 2 at the positive electrode and 78.2 Ah / m 2 at the negative electrode. It should be noted that for the current [mA / cm 2 in this example, it is normalized by the area of the positive electrode plate.

[0122] For the test battery fabricated as described above, the following evaluations are carried out. The results are shown in Table 1.

[0123] (Internal resistance)

[0124] At a temperature of 25 °C, the SOC (State of Charge) of the test battery is adjusted to 50% by constant current-constant voltage (CC-CV) charging (CC current = 1 / 3C, CV voltage = 3.7 V, 1 / 20C cut-off). Then, the temperature is adjusted by maintaining it at -30 °C for more than 5 hours. The voltage is measured by discharging for 10 seconds respectively with current values of 0.1C, 0.2C, 0.3C, 0.4C, 0.5C, and 0.6C. After the voltage measurement at each current value, according to the discharge capacity, it is charged with 0.05C to suppress the change in SOC, and then stopped for 30 minutes. From the I-V graph, the resistance is calculated by linear approximation. In this example, the internal resistance of Comparative Example 1 is defined as 100. If the internal resistance is 120 or less, the output characteristics are considered good.

[0125] (Boron content)

[0126] After charging the test battery (cut-off at 0.05C and 4.2V) and discharging (cut-off at 0.05C and 3.0V), disassemble it. As Figure 4 shown, take out the wound electrode body having the electrode plates 13 and 23, the length L in the width direction of the active material layer, the upper R portion (the curved portion on the upper side of the wound body), and the lower R portion (the curved portion on the lower side of the wound body). The electrode plate 13 is the portion (substrate) where the positive electrode active material layer is not formed in the positive electrode plate, and the electrode plate 23 is the portion (substrate) where the positive electrode active material layer is not formed in the negative electrode plate. As Figure 5 shown, cut out the central region M2 from the portion corresponding to the outermost layer of the negative electrode plate in the taken-out negative electrode plate. Then, strip the negative electrode active material in 10 ml of water to collect a sample for boron content measurement. The center of the central region M2 is a region with a radius of 20 mm centered on the midpoint of L and h. L is the length of the short side of the negative electrode active material layer, and h is the distance between the vertex of the upper R portion and the vertex of the lower R portion of the electrode body in the negative electrode active material layer. Add 10 mL of hydrochloric acid to the water containing the sample for boron content measurement, and heat-treat it at 80°C for 30 minutes. Filter the obtained aqueous solution with filter paper, add water to the filter paper deposit, and also recover the filter paper adherends. Then, make the volume of the recovered aqueous solution 100 mL, perform B-ICP measurement, and obtain the boron content M2 (mass%) of the central portion of the negative electrode active material layer by the external calibration curve method (external calibration curve method).

[0127] Next, in the same manner as the central region M2, for Figure 4 the remaining 8 regions other than M2 surrounded by a circle as shown, measure the boron content, and take the average value of the boron contents obtained from the 9 regions including M2 as the average boron content M1 (mass%) of boron contained in the negative electrode active material layer.

[0128] (Specific surface area)

[0129] Measure the BET specific surface area of the negative electrode plate taken out from the disassembled electrode body in the measurement of boron content by the nitrogen adsorption method.

[0130] (Penetration test)

[0131] Charge the test battery. Connect the test battery to the data logger. The data logger has a voltage measurement function and a current measurement function. Prepare a nail (manufactured by Daito Hunt Co., round nail, trunk diameter = 3 mm). Pierce the nail into the test battery. Stop piercing the nail when the voltage drop is confirmed. After the nail stops, measure the voltage and current until a voltage rise is detected. It is considered that the voltage drop indicates the occurrence of a short circuit. It is considered that the voltage rise after the voltage drop indicates that due to the Joule heat of the short circuit, the positive electrode substrate (Al foil) around the nail melts and spreads, blocking the current. Calculate the heat generation amount from the voltage, current, and time during the period until a voltage rise is detected. It is considered that the smaller the heat generation amount, the better the fusing performance. In Table 1, the case where the heat generation amount is less than 35 W is indicated as ○, and the case where the heat generation amount is 35 W or more is indicated as ×.

[0132] <Examples 2 to 3 and Comparative Examples 1 to 5>

[0133] Except for changing the composition ratio of the positive electrode active material, the type and specific surface area of the negative electrode active material, the specific surface area of the negative electrode active material layer, the content of LiBOB in the electrolyte, and the boron content as shown in Table 1, test batteries were manufactured in the same manner as in Example 1. The results are shown in Table 1.

[0134]

[0135] In Examples 1 to 3, good results were obtained in the nail penetration test while suppressing the increase in resistance.

[0136] The embodiments of the present invention have been described. It should be considered that the embodiments disclosed this time are illustrative in all aspects and not restrictive. The scope of the present invention is represented by the claims and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A non-aqueous electrolyte secondary battery comprising an electrode body and an electrolyte solution, The electrode body comprises a positive electrode plate and a negative electrode plate, The positive electrode plate comprises a positive electrode active material layer, The negative electrode plate comprises a negative electrode active material layer, The positive electrode active material layer includes a positive electrode active material represented by formula (1): Li (1+x) Ni y You z Me (1-y-z) O2 In formula (1), Me includes two or more selected from Mn, Co and Al, and satisfies the relationship of 0<x<0.1, 0.8<y<0.85, 0≤z<0.03, The negative electrode active material layer contains a negative electrode active material. When the specific surface area of ​​the negative electrode active material layer is set to S, the average boron content of the boron contained in the negative electrode active material layer is set to M1 (mass %), and the boron content in the central portion of the negative electrode active material layer is set to M2 (mass %), the following relationship is satisfied: (a)M1 / S≤0.1 (b)M2≥0.

05.

2. The nonaqueous electrolyte secondary battery according to claim 1, wherein The total relative area of ​​the electrode body is 3m 2 above, The length of the short side of one continuous negative electrode active material layer in the negative electrode plate in a plan view is 80 mm or more and 400 mm or less.

3. The nonaqueous electrolyte secondary battery according to claim 1 further satisfies the following relationship: (c)2≤S≤4.

4. The nonaqueous electrolyte secondary battery according to claim 1, wherein The graphite content in the negative electrode active material is 99 mass % or more.

5. A method for manufacturing a non-aqueous electrolyte secondary battery, comprising: The step of inserting the electrode assembly into the outer casing, The process of injecting electrolyte, and Activation process, The electrode body comprises a positive electrode plate and a negative electrode plate, The positive electrode plate comprises a positive electrode active material layer. The negative electrode plate comprises a negative electrode active material layer, The positive electrode active material layer includes a positive electrode active material represented by formula (1): Li (1+x) Ni y You z Me (1-y-z) O2 In formula (1), Me includes two or more selected from Mn, Co and Al, and satisfies the relationship of 0<x<0.1, 0.8<y<0.85, 0≤z<0.03, The negative electrode active material layer contains a negative electrode active material. When the specific surface area of ​​the negative electrode active material layer is set to S, the average boron content of the boron contained in the negative electrode active material layer is set to M1 (mass %), and the boron content in the central portion of the negative electrode active material layer is set to M2 (mass %), the following relationship is satisfied: (a)M1 / S≤0.1 (b)M2≥0.05.

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