Nonaqueous electrolyte secondary battery

Abstract

The present disclosure provides a nonaqueous electrolyte secondary battery in which a positive electrode active material layer contains a positive electrode active material represented by formula (1): Li (1 + x) NiyTizMe (1-y-z) O2, and when the specific surface area of a negative electrode active material layer is set as S (m2 / g), the relational expression (a): 10x + 2 < Sis satisfied. According to the present disclosure, provided is a nonaqueous electrolyte secondary battery having a high initial cycle capacity retention rate and suppressed decrease in cycle capacity retention rate after a storage endurance test.

Description

Technical Field The present disclosure relates to a nonaqueous electrolyte secondary battery. Background Art Japanese Patent Application Laid-Open No. 2011-113825 proposes a positive electrode material for a lithium ion secondary battery having a high nickel content. Summary of the invention When a lithium composite oxide with a high nickel content is used for the positive electrode active material layer, although it is possible to increase the capacity of a nonaqueous electrolyte secondary battery (hereinafter also referred to as a battery), side reactions in the negative electrode and the positive electrode and capacity degradation of the positive electrode active material tend to occur easily during storage durability tests. Due to the above-mentioned side reactions, the capacity-potential curves in the positive electrode and the negative electrode (hereinafter also referred to as the positive electrode single-pole curve and the negative electrode single-pole curve, respectively) are sometimes shifted ( Figure 1 , Figure 2 , Figure 3 ). If the total of the shift amount of the positive electrode single-pole curve (hereinafter also referred to as the positive electrode shift amount) and the capacity degradation of the positive electrode active material becomes larger than the shift amount of the negative electrode single-pole curve (hereinafter also referred to as the negative electrode shift amount), the reserve capacity of the negative electrode decreases, and as a result, lithium (Li) is precipitated at the negative electrode, which tends to easily cause a decrease in the cycle capacity retention rate. An object of the present disclosure is to provide a nonaqueous electrolyte secondary battery having a high initial cycle capacity retention rate and in which a decrease in the cycle capacity retention rate after a storage durability test is suppressed. The present disclosure provides the following nonaqueous electrolyte secondary battery.

[0001] A non-aqueous electrolyte secondary battery comprising an electrode body, 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 contains a positive electrode active material represented by formula (1): Li (1+x) Ni y Ti z Me (1-y-z) O 2 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, The negative electrode active material layer contains a negative electrode active material. The negative electrode active material includes graphite. When the specific surface area of ​​the negative electrode active material layer is denoted as S (m 2 / g), the following relationship is satisfied: (a)10x+2<S.

[0002] The nonaqueous electrolyte secondary battery according to [1], further satisfying (b) S<10x+3.4.

[0003] The nonaqueous electrolyte secondary battery according to [1] or [2], wherein the graphite content in the negative electrode active material is 99 mass % or more.

[0004] The nonaqueous electrolyte secondary battery according to any one of [1] to [3], wherein in formula (1), the relationship of 0.01<z<0.03 is satisfied. The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 It is a schematic diagram for explaining the positive electrode single-pole curve, the negative electrode single-pole curve, the battery capacity, and the reserve capacity. Figure 2 This is a schematic diagram for explaining the displacement of the negative electrode. Figure 3 This is a schematic diagram for explaining the positive electrode displacement. Figure 4 It is a schematic diagram showing an example of the configuration of a battery in this embodiment. Figure 5 It is a schematic diagram showing an example of the structure of the electrode body in this embodiment. Figure 6 It is a graph for explaining the relationship between the reserve capacity and the cycle capacity maintenance rate of the negative electrode. Figure 7 It is a graph for explaining the relationship between the specific surface area of ​​the negative electrode active material layer and the irreversible Li amount of the negative electrode caused by the storage durability test. Figure 8 It is a graph for explaining the relationship between the composition of the positive electrode active material layer and the positive electrode displacement amount. Fig. 9 It is a graph for explaining the relationship between the composition of the positive electrode active material layer and the specific surface area of ​​the negative electrode active material layer with respect to the cycle capacity retention rate after the storage durability test. Fig.10 It is a graph for explaining the relationship between the composition of the positive electrode active material layer and the specific surface area of ​​the negative electrode active material layer with respect to the capacity retention rate after the storage durability test. DETAILED DESCRIPTION Below, while referring to the attached Figure 1The embodiments of the present invention are described, 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 to represent, and the scale of each component shown in the drawings is not necessarily consistent with the scale of the actual component. In the following description of each embodiment, the same or equivalent parts in the drawings are marked with the same figure mark, and their description is not repeated. <Non-aqueous electrolyte secondary battery> Figure 4 It is a schematic diagram showing an example of the configuration of a battery in this embodiment. The battery 100 can be used in any application. For example, the battery 100 can be used as a main power source or a power auxiliary power source in an electric vehicle. A battery module or a battery pack can be formed by connecting a plurality of batteries 100. The battery 100 includes an outer casing 90. The outer casing 90 is square (flat rectangular). However, the square is just an example. The outer casing 90 may have any shape. The outer casing 90 may be, for example, cylindrical or pouch-shaped. The outer casing 90 may be made of, for example, an Al alloy. The outer casing 90 contains an electrode body 50 and an electrolyte (not shown). The outer casing 90 may include, for example, a sealing plate 91 and an outer can 92. The sealing plate 91 plugs the opening of the outer can 92. For example, the sealing plate 91 and the outer can 92 may be joined by laser welding. The sealing plate 91 is provided with a positive terminal 81 and a negative terminal 82. The sealing plate 91 may further be provided with an injection port and a gas discharge valve. The electrolyte may be injected into the interior of the outer casing 90 from the injection port. The electrode body 50 is connected to the positive terminal 81 through the positive electrode collector member 71. The positive electrode collector member 71 may be, for example, an Al plate. The electrode body 50 is connected to the negative terminal 82 through the negative electrode collector member 72. The negative electrode collector member 72 may be, for example, a Cu plate. Figure 5 Schematic diagram showing an example of the structure of the electrode body in the present embodiment. The electrode body 50 is of a winding 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 a plurality of separators 30. The electrode body 50 is formed by stacking the positive electrode plate 10, the separator 30 and the negative electrode plate 20 in sequence and winding them into a spiral shape. One of the positive electrode plate 10 or the negative electrode plate 20 can be clamped in the separator 30. Both the positive electrode plate 10 and the negative electrode plate 20 can be clamped in the separator 30. The electrode body 50 can be formed into a flat shape after winding. It should be noted that the winding type is an example. The electrode body 50 can be, for example, a stacked (stacked) type. (Positive plate) 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. 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, for example, be disposed only on one side of the positive electrode substrate 11. The positive electrode active material layer 12 may, for example, be disposed on both the front and back sides of the positive electrode substrate 11. In the width direction ( Figure 2 The positive electrode substrate 11 may be exposed at one end. The positive electrode current collecting member 71 may be joined to the exposed portion of the positive electrode substrate 11. 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, when there is an intermediate layer, it is also considered that the positive electrode active material layer 12 is arranged 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, etc. (Positive Electrode Active Material Layer) The positive electrode active material layer 12 contains a positive electrode active material. The positive electrode active material contains the following formula (1): Li (1+x) Ni y Ti z Me (1-y-z) O 2 [In formula (1), Me contains two or more selected from Mn, Co and Al, Satisfying the relationship 0<x<0.1, 0.8<y<0.85, 0≤z<0.03] Represents a layered metal oxide. The layered metal oxide represented by the formula (1) may satisfy the following relationships, for example, 0<x<0.2, 0.8<y<0.84, and 0.01<z<0.03. 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. 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. 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. 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 independently may have any crystal structure. The first positive electrode active material particles and the second positive electrode active material particles independently may have, for example, 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 may have substantially the same chemical composition. The first positive electrode active material particles and the second positive electrode active material particles may have different chemical compositions from each other. As for the positive electrode active material layer 12, as long as it contains the positive electrode active material, it may further contain additional components. In addition to the positive electrode active material, the positive electrode active material layer 12 may include, for example, a conductive material and a binder. The conductive material may include any component. The conductive material may, for example, include at least one selected from carbon black, graphite, vapor grown carbon fiber (VGCF), carbon nanotube (CNT) and graphene sheets. The amount of the conductive material may be, for example, 0.1 to 10 parts by mass relative to 100 parts by mass of the positive electrode active material. The binder may include any component. The binder may include, for example, at least one selected from polyvinylidene fluoride (PVdF), poly(vinylidene fluoride-co-hexafluoropropylene (PVdF-HFP), polytetrafluoroethylene (PTFE) and polyacrylic acid (PAA). The amount of the binder may be, for example, 0.1 to 10 parts by mass relative to 100 parts by mass of the positive electrode active material. The positive electrode active material layer 12 may include, for example, 80% to 99% of the positive electrode active material, 0.1% to 10% of the conductive material, and the remainder of the binder, in terms of mass fraction. The positive electrode active material layer 12 may have a thickness of, for example, 10 μm to 200 μm. The positive electrode active material layer 12 may have a thickness of, for example, 50 μm to 150 μm. The positive electrode active material layer 12 may have a thickness of, for example, 50 μm to 100 μm. The positive electrode active material layer 12 may have a high density. For example, the positive electrode active material layer 12 may have a density of 3.3 g / cm 3 Up to 3.9g / cm 3 The positive electrode active material layer 12 may have a density of, for example, 3.4 g / cm 3 Up to 3.7g / cm 3The positive electrode active material layer 12 may have a density of, for example, 3.4 g / cm 3 Up to 3.6g / cm 3 The density of the active material layer in this specification means the apparent density. The positive electrode plate 10 is manufactured by applying a positive electrode slurry on the surface of a positive electrode substrate 11 to form a positive electrode active material layer 12, then rolling the positive electrode active material layer 12 and the positive electrode substrate 11 to produce a raw sheet (raw sheet), and then cutting it into a predetermined plane size according to the specifications of the battery 100. The positive electrode slurry is prepared by mixing a positive electrode active material and an additional component. (Negative plate) 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. 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 sides of the negative electrode substrate 21. In the width direction ( Figure 2 The negative electrode substrate 21 may be exposed at one end. The negative electrode current collecting member 72 may be joined to the exposed portion of the negative electrode substrate 21. (Negative Electrode Active Material Layer) The negative electrode active material layer 22 contains a negative electrode active material. The negative electrode active material may contain any component. 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. As for the negative electrode active material layer 22, in addition to the negative electrode active material, other components may further include, for example, a binder. The negative electrode active material layer 22 may include, for example, 95% to 99.5% of the negative electrode active material and the remainder of the binder, by mass fraction. The binder may include any component. The binder may include, for example, at least one selected from carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR). In the case where the negative electrode active material layer 22 includes 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. The specific surface area of ​​the negative electrode active material layer 22 may be, for example, greater than 2, greater than 2 and less than 4.5, or greater than 2 and less than 4. The specific surface area S of the negative electrode active material layer 22 is the specific surface area of ​​the negative electrode active material layer of the negative electrode plate taken out of the activated battery. The specific surface area S of the negative electrode active material layer 22 is measured by the method described in the column of Examples described later. The negative electrode active material layer 22 may have a thickness of, for example, 10 μm to 200 μm. The negative electrode active material layer 22 may have a high density. For example, the negative electrode active material layer 22 may have a density of 1.0 g / cm 3 Up to 2.0g / cm 3 The negative electrode active material layer 22 may have a density of, for example, 1.2 g / cm 3 Up to 1.7g / cm 3 The negative electrode active material layer 22 may have a density of, for example, 1.3 g / cm 3 Up to 1.6g / cm 3 density. The negative electrode plate 20 is manufactured by applying a negative electrode slurry on the surface of a negative electrode substrate 21 to form a negative electrode active material layer 22, then rolling the negative electrode active material layer 22 and the negative electrode substrate 21 to produce a raw sheet, and then cutting it into a predetermined plane size according to the specifications of the battery 100. The negative electrode slurry is prepared by mixing a negative electrode active material and other components. [Relation (a)] It can be seen that the cycle capacity maintenance rate is correlated with the reserve capacity of the negative electrode ( Figure 6 ). If the positive displacement y1(Ah / m 2 ) and the capacity degradation of the positive electrode active material (Ah / m 2 ) becomes greater than the negative electrode displacement y2 (Ah / m 2 ) is large, the negative electrode storage capacity (Ah / m 2 ) tends to be easily reduced. The negative electrode displacement amount y2 tends to decrease as the amount of irreversible Li in the negative electrode decreases. The amount of irreversible Li in the negative electrode tends to be dependent on the specific surface area of ​​the negative electrode active material layer ( Figure 7 ). On the other hand, the inventors' research results show that the positive electrode shift amount y1 has a strong correlation with the Li / M (=1+x) ratio (M is the total of metals other than Li in the positive electrode active material) in the positive electrode active material. Figure 8 ). Therefore, a study was conducted on controlling the specific surface area of ​​the negative electrode active material layer according to the Li / M ratio of the positive electrode active material. As a result, it was found that when the specific surface area of ​​the negative electrode active material layer 22 is set to S, by satisfying the following relationship: (a) 10x+2<S, the initial cycle capacity maintenance rate can be improved, and at the same time, the decrease in the cycle capacity maintenance rate in the endurance test can be suppressed. In relational expression (a), an approximate straight line ( Figure 7), and the approximate straight line when the positive pole displacement y1 is plotted against x ( Figure 8 ) The xS straight line obtained in a manner that at least satisfies the relationship of positive electrode displacement amount y1 < negative electrode displacement amount y2 is applied so that the decrease in the cycle capacity maintenance rate is suppressed (satisfying the cycle capacity maintenance rate ≥ 95%) ( Fig. 9 ), and thus it is obtained. In the relational expression (a), x is defined as in the above-mentioned expression (1). The specific surface area S of the negative electrode active material layer 22 is measured by the method described in the column of Examples described later. [Relation (b)] The battery can further satisfy the following relationship: (b)S<10x+3.4. It was found that: when the battery satisfies the relational expression (b), the precipitation of lithium is suppressed after the endurance test, and as a result, the decrease in the capacity retention rate during the storage endurance test is easily suppressed. When the battery satisfies the relational expressions (a) and (b), the decrease in the cycle capacity retention rate is also suppressed after the endurance test, and the decrease in the capacity retention rate during the endurance test tends to be easily suppressed. Regarding relational expression (b), by applying the xS straight line obtained as described above, the decrease in the capacity retention rate in the storage durability test is suppressed (satisfying the capacity retention rate after 120 days ≥ 95%) ( Fig.10 ) and find the answer. (Facing Capacity Ratio) The relative capacity ratio (ratio of the negative electrode capacity to the positive electrode capacity) can be, for example, 1.00 to 1.15, preferably 1.04 to 1.10. The negative electrode capacity is calculated by multiplying the total mass of the negative electrode active material contained in the negative electrode active material layer 22 by the specific capacity of the negative electrode active material. The positive electrode capacity is calculated by multiplying the total mass of the positive electrode active material contained in the positive electrode active material layer 12 by the specific capacity of the positive electrode active material. (Spacer) At least a portion of the separator 30 is interposed between the positive electrode plate 10 and the negative electrode plate 20. The separator 30 separates the positive electrode plate 10 from the negative electrode plate 20. The separator 30 may have a thickness of, for example, 10 μm to 30 μm. The separator 30 is a porous sheet. The separator 30 allows the electrolyte to pass through. The separator 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. The spacer 30 is electrically insulating. The spacer 30 may include, for example, a polyolefin resin. The spacer 30 may be substantially composed of, for example, a polyolefin resin. The polyolefin resin may include, 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 a PE layer. The spacer 30 may have, for example, a multi-layer structure. The spacer 30 may be formed by sequentially stacking, for example, a PP layer, a PE layer, and a PP layer. On the surface of the spacer 30, for example, a heat-resistant layer may be formed. (Electrolyte) The electrolyte comprises a solvent and a supporting electrolyte. The solvent is aprotic. The solvent may contain any component. The solvent may, for example, contain 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). The supporting electrolyte is dissolved in the solvent. The supporting electrolyte may include, for example, LiPF 6 , LiBF 4 and LiN(FSO 2 ) 2 At least one of. 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. The electrolyte may further include any additive. For example, the electrolyte may include 0.01% to 5% of additives, expressed as mass fraction. The additives may include, for example, vinylene carbonate (VC), lithium difluorophosphate (LiPO 2 F 2 ), lithium fluorosulfonate (FSO 3 At least one of lithium bis(oxalatoborate) (Li) and lithium bis(oxalatoborate) (LiBOB). <Battery Manufacturing Method> The method for manufacturing a battery in the present embodiment includes a step (A) of inserting an electrode assembly into an outer casing, a step (B) of injecting an electrolyte solution, and an activation step (C). In the step (A) of inserting the electrode body into the outer casing, the electrode body 50 is housed in the outer casing 90. The electrode body 50 may be connected to the positive electrode terminal 81 via the positive electrode current collecting member 71. The electrode body 50 may be connected to the negative electrode terminal 82 via the negative electrode current collecting member 72, for example. In the step (B) of injecting the electrolyte solution, the electrolyte solution is injected into the outer casing 90. The electrolyte solution is impregnated into the electrode body 50. After the electrolyte solution is injected, the outer casing 90 is sealed. 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 predetermined time, the battery 100 is discharged in a constant current (CC-CV) manner. More specifically, the battery 100 is activated at 0.2 mA / cm 2 The current is charged at a constant current until the positive electrode potential reaches 4.30V (vs.Li + / Li), and then charged at a constant voltage until the current reached 0.04 mA / cm 2 Then, after a 10-minute pause, the 2 The current is discharged at a constant current until the positive electrode potential reaches 2.5V (vs.Li + / Li). As described above, the battery 100 is manufactured. The manufactured battery 100 satisfies the relational expressions (a) and (b) as described above, thereby suppressing the increase of the internal resistance and having good fuse properties. The cycle capacity maintenance rate of the battery can be 95% or more. In addition, the cycle capacity maintenance rate of the battery after the storage durability test can also be 95% or more. When the cycle capacity maintenance rate after the storage durability test is also 95% or more, the battery can have good cycle characteristics. Furthermore, the capacity maintenance rate of the battery after a 120-day storage durability test can be 95% or more. When the capacity maintenance rate after a 120-day storage durability test is also 95% or more, the battery can have good storage durability characteristics. Hereinafter, embodiments of the present technology will be described, but the following description does not limit the scope of the present technology. Example <Example 1> (Manufacturing of positive electrode plates) By using lithium nickel composite oxide (Li 1.03 Ni 0.82 Co 0.05 Mn 0.11 O 2 ) 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. (Manufacturing of negative electrode plates) By mixing 98 parts by mass of the negative electrode active material (natural 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 4 (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. (Assembly) 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. (Injection of electrolyte) 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. Solvent: EC / EMC=3 / 7 (volume ratio) Supporting electrolyte: LiPF 6 (1mol / L) Additive: LiBOB (mass fraction 0.5%) (activation) Initial charge and discharge were performed at 25°C. 2 The test battery was charged at a constant current until the positive electrode potential reached 4.30 V (vs. Li + / Li). Then, the test cell was charged at a constant voltage until the current reached 0.04 mA / cm 2 The initial charge capacity was measured by this method. After a 10-minute pause, the 2 The test battery was discharged at a constant current until the positive electrode potential reached 2.5V (vs.Li + / Li). The initial discharge capacity was thus determined. <Measurement of capacity maintenance rate> The battery capacity of the activated test battery was measured under the following conditions in a temperature environment of 25° C. before and after the cycle test. Constant current (CC) charging: CC current: 0.05C, 4.2V cutoff Constant current (CC) discharge: CC discharge: 0.05C, 3.0V cutoff The capacity maintenance rate is as follows: Capacity retention rate = (battery capacity after cycle test / battery capacity before cycle test) × 100 (%) Figure it out. The cycle durability test was carried out under the following conditions. Temperature: 25℃ Number of cycles: 100 cycles Constant current-constant voltage (CC-CV) charging: CC current = 1C, CV voltage = 4.2V, 0.05C cutoff Stop: 1 minute Constant current (CC) discharge: CC current = 1C, 3.0V cutoff Stop: 10 minutes The capacity retention rate was similarly measured for the test battery after the storage durability test (after 120 days) described later. The results are shown in Table 1. <Storage durability test> The activated test battery was subjected to constant current (CC) charging (current = 0.05C, 4.2V cut-off) and then stored in a 60°C thermostat for 120 days. The battery capacity before the storage endurance test and on the 30th, 60th, 90th and 120th days of storage was measured under the following conditions at a temperature of 25°C. Constant current (CC) charging: CC current: 0.05C, 4.2V cutoff Constant current (CC) discharge: CC discharge: 0.05C, 3.0V cutoff The capacity maintenance rate is as follows: Capacity retention rate = (battery capacity at each storage day / battery capacity before storage durability test) × 100 (%) The results are shown in Table 1. <Specific surface area> The BET specific surface area of ​​the negative electrode plate taken out from the electrode assembly after initial charge and discharge was measured by a nitrogen adsorption method. <Measurement of single-electrode charge and discharge capacity> The activated test battery was charged and discharged under the following conditions in a temperature environment of 25°C. Constant current (CC) charging: CC current: 0.05C, 4.2V cutoff Constant current (CC) discharge: CC discharge: 0.05C, 3.0V cutoff After charge and discharge, the test battery was disassembled, the positive plate and negative plate were taken out, and a single-pole battery of positive plate-counter electrode Li foil (hereinafter referred to as positive battery) and a single-pole battery of negative plate-counter electrode Li foil (hereinafter referred to as negative battery) were made. The electrolyte was EC / EMC=3 / 7_LiPF6:1mol / l. Then, the positive electrode remaining discharge amount of the positive electrode battery was measured by constant current (CC) discharge (CC current=0.05C, 2.5V cutoff), and then the positive electrode capacity was measured under the following conditions. Constant current (CC) charging: CC current = 0.05C, 4.3V cutoff Stop: 10 minutes Constant current (CC) discharge: CC current = 0.05C, 2.5V cutoff Next, the negative electrode residual discharge capacity of the negative electrode battery was measured by constant current (CC) charging (CC current = 0.05 C, 2.0 V cutoff), and then the positive electrode capacity was measured under the following conditions. Constant current (CC) discharge: CC current = 0.05C, 0.001V cutoff Stop: 10 minutes Constant current (CC) charging: CC current = 0.05C, 2.0V cutoff The single-electrode charge capacity and discharge capacity were similarly measured for the test batteries after the storage endurance test (after 120 days). Table 1 shows the initial single-electrode charge capacity and discharge capacity. <Li-ICP measurement> The activated test battery was charged and discharged under the following conditions in a temperature environment of 25°C. Constant current (CC) charging: CC current: 0.05C, 4.2V cutoff Constant current (CC) discharge: CC discharge: 0.05C, 3.0V cutoff Disassemble the test battery after charge and discharge and cut out 10cm 2 The negative electrode plate was stripped in 10 ml of water, 10 ml of hydrochloric acid was added, and the solution was treated at 80°C for 30 minutes. Water was added to the filter paper deposits, and the adhered part was also recovered to make the recovered aqueous solution 100 ml. B-ICP measurement was performed, and the Li amount was obtained by the external calibration curve method (external calibration curve method). The amount of Li was similarly determined for the test battery after the storage endurance test (after 120 days). <Positive pole shift amount, negative pole shift amount, reserve capacity, positive-negative pole deviation amount> Positive displacement (Ah / m 2 ) as the displacement from the negative electrode (Ah / m 2 ) minus the positive-negative electrode deviation after the storage durability test (Ah / m 2 ) and initial positive-negative electrode deviation (Ah / m 2 ) is calculated by the difference between the two. Negative displacement (Ah / m 2 ) is the amount of Li in the negative electrode after the storage durability test (Ah / m 2 ) and negative electrode residual discharge capacity (Ah / m 2 ) minus the initial negative electrode Li amount (Ah / m 2 ) and negative electrode residual discharge capacity (Ah / m 2 ) is calculated by the difference between the two. Reserve capacity (Ah / m 2 ) as the discharge capacity of the negative electrode (Ah / m 2 ) minus the battery capacity (Ah / m 2 ) and negative electrode residual discharge capacity (Ah / m 2 ) is calculated using the amount obtained. The positive-negative deviation (Ah / m 2 ) as the remaining discharge capacity (Ah / m 2 ) minus the negative electrode remaining discharge capacity (Ah / m 2 ) is calculated using the amount obtained. <Examples 2 to 7 and Comparative Examples 1 to 5> A test cell was manufactured in the same manner as in Example 1 except that the composition ratio of the positive electrode active material, the type of the negative electrode active material, the ratio of the negative electrode active material in the case of a mixture, the specific surface area of ​​the negative electrode active material, and the specific surface area of ​​the negative electrode active material layer were changed as shown in Table 1. The results are shown in Table 1. In Examples 1 to 7 according to the present disclosure, the initial cycle capacity maintenance rate is 95% or more, and the cycle capacity maintenance rate is also 95% or more after the storage durability test. Furthermore, in Examples 2 to 7, the capacity maintenance rate after the storage durability test is 95% or more. On the other hand, in Comparative Examples 1 to 2, although the initial cycle capacity maintenance rate is 95% or more, the cycle capacity maintenance rate decreases after the storage durability test. In addition, in Comparative Examples 3 to 5, the initial cycle capacity maintenance rate is low, and the cycle capacity maintenance rate decreases after the storage durability test. Although the embodiments of the present invention have been described, the embodiments disclosed this time should be considered to be illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims, and it 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, 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 and 0≤z<0.03, The negative electrode active material layer contains a negative electrode active material. The negative electrode active material comprises graphite, When the specific surface area of ​​the negative electrode active material layer is denoted as S (m 2 / g), the following relationship is satisfied: (a)10x+2<S. 2 . The nonaqueous electrolyte secondary battery according to claim 1 , further satisfying (b) S<10x+3.

4.

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

4. The nonaqueous electrolyte secondary battery according to claim 1, wherein In the formula (1), the relationship of 0.01<z<0.03 is satisfied.

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