JP2014179221A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-capacity nonaqueous electrolyte secondary battery superior in cycle characteristics.SOLUTION: A nonaqueous electrolyte secondary battery comprises: a positive electrode having a positive electrode mixture layer including a positive electrode active material; a negative electrode having a negative electrode mixture layer including a negative electrode active material and; a porous insulator layer interposed therebetween; and a nonaqueous electrolyte. The negative electrode active material includes graphite, and silicon oxide including silicon and oxygen as constituent elements (where the atomic ratio x of oxygen to the total quantity of silicon satisfies the following condition: 0.5≤x≤1.5). The rate of the silicon oxide to the total quantity of the graphite and the silicon oxide is 1-20 pts.mass. The positive electrode and the negative electrode are opposed to each other through the porous insulator layer and form electrode-plate wound assembly. Supposing that the thickness of the porous insulator layer is A(μm), and the inter-electrode distance from the surface of the positive electrode mixture layer to the surface of the negative electrode mixture layer opposed thereto is B(μm), "A" and "B" satisfy the following Expression 1: (Expression 1) A≤B≤A×1.3.

Description

  The present invention relates to a non-aqueous electrolyte secondary battery, and in particular, a Si oxide containing graphite and Si and O (wherein the atomic ratio x of O to the total amount of Si is 0.5 ≦ x ≦ 1. 5 is a non-aqueous electrolyte secondary battery having excellent cycle characteristics.

  In recent years, many mobile and portable electronic devices such as mobile phones including smartphones, portable personal computers, PDAs, and portable game machines have appeared. In view of the demand for higher functionality, smaller size, and lighter weight of these devices, it is desired to further increase the capacity of the secondary battery as the driving power source.

  In addition, due to the recent increase in environmental protection movements, exhaust gas emission regulations that cause global warming, such as carbon dioxide, have been strengthened. In the automobile industry, electric vehicles (EV) and hybrid electric vehicles (HEV, PHEV) are being actively developed in place of vehicles using fossil fuels such as gasoline, diesel oil, and natural gas.

  As these driving batteries, nickel-hydrogen secondary batteries and lithium ion secondary batteries are used. However, in recent years, a lightweight and high capacity battery can be obtained. Non-aqueous electrolyte secondary batteries such as these have been increasingly used.

  In addition, non-water storage battery systems such as photovoltaic power generation and wind power generation are also used for stationary storage battery systems such as applications for suppressing output fluctuations and grid power peak shift applications for storing power during the daytime. The use of electrolyte secondary batteries is increasing.

  As the negative electrode active material used in this non-aqueous electrolyte secondary battery, carbonaceous materials such as graphite and amorphous carbon have a discharge potential comparable to that of lithium metal or lithium alloy, but dendrite grows. Therefore, it is widely used because it has excellent properties such as high safety, excellent initial efficiency, good potential flatness, and high density.

However, when a negative electrode active material made of a carbon material is used, lithium can only be inserted up to the composition of LiC ₆ and the theoretical capacity is 372 mAh / g, which is an obstacle to increasing the capacity of the battery. Yes.

  Therefore, non-aqueous electrolyte secondary batteries using silicon or silicon alloys or silicon oxide (hereinafter referred to as high capacity negative electrode materials) alloyed with lithium have been developed as negative electrode active materials having high energy density per mass and per volume. .

In this case, for example, since silicon can insert lithium up to the composition of Li _4.4 Si, the theoretical capacity is 4200 mAh / g, and a capacity much larger than that when a carbon material is used as the negative electrode active material can be expected.

  However, when silicon or a silicon alloy, silicon oxide, or the like is used as the negative electrode active material of the non-aqueous electrolyte secondary battery, the negative electrode active material undergoes large expansion / contraction as the charge / discharge cycle progresses. There is a problem that the cycle characteristics of the battery are deteriorated because the substance is pulverized or missing from the conductive network, and various improvements have been made to solve these problems.

  As one of such high-capacity negative electrode materials for non-aqueous electrolyte secondary batteries, the following Patent Document 1 discloses, as a negative electrode, a compound containing Si and O as constituent elements (hereinafter referred to as Si oxide), graphite, and a conductive material. Non-aqueous electrolyte secondary batteries having a negative electrode mixture layer containing

JP 2008-210618A

  According to the nonaqueous electrolyte secondary battery disclosed in Patent Document 1, since the Si oxide having a large volume change associated with charge / discharge is used, the expansion rate of the negative electrode mixture layer is increased.

  However, the negative electrode mixture layer forms an electrode plate winding body in close contact with the positive electrode mixture layer and the porous insulating layer, and the electrode plate winding body is fixed with an adhesive tape.

  Therefore, when the negative electrode mixture layer expands during charging, the electrolytic solution held in the negative electrode mixture layer is pushed out of the electrode plate roll. In this way, when the electrolytic solution held in the negative electrode mixture layer is once pushed out of the electrode plate winding body, it is difficult to return to the electrode plate winding body again. Every time it is done, the electrolyte solution in the negative electrode mixture layer is pushed out, resulting in a shortage of the cycle characteristics.

  The present invention has been made to solve the above-mentioned problems of the prior art, and is a Si oxide containing Si and O as constituent elements as a negative electrode active material (however, the atomic ratio x of O to the total amount of Si x Is 0.5 ≦ x ≦ 1.5), and an object thereof is to provide a nonaqueous electrolyte secondary battery excellent in cycle characteristics.

In order to achieve the above object, a non-aqueous electrolyte secondary battery of the present invention includes a positive electrode including a positive electrode mixture layer including a positive electrode active material, a negative electrode including a negative electrode mixture layer including a negative electrode active material, and a porous A non-aqueous electrolyte secondary battery comprising a porous insulating layer and a non-aqueous electrolyte in which a lithium salt is dissolved in a non-aqueous solvent, wherein the negative electrode active material includes graphite, and Si oxide containing Si and O as constituent elements (However, the atomic ratio x of O to the total amount of Si is 0.5 ≦ x ≦ 1.5), and the ratio of the Si oxide to the total amount of the graphite and the Si oxide is 1 part by mass. 20 parts by mass or less, and the positive electrode and the negative electrode face each other through the porous insulating layer to form an electrode plate wound body, the thickness of the porous insulating layer is A (μm), Distance between electrodes from the surface of the positive electrode mixture layer to the surface of the opposite negative electrode mixture layer If the the B ([mu] m), the relationship of A and B is characterized by satisfying the following equation 1.
(Formula 1) A ≦ B ≦ A × 1.3

  The non-aqueous electrolyte secondary battery of the present invention is not limited to graphite as a negative electrode active material, but also an Si oxide containing Si and O as constituent elements (however, the atomic ratio x of O to the total amount of Si is 0.5 ≦ x ≦ 1.5).

  Note that Si oxides containing Si and O as constituent elements include Si oxides represented by SiOx (0.5 ≦ x ≦ 1.5). Such a Si oxide represented by SiOx has a larger volume change due to charge / discharge than the graphite material, but a theoretical capacity value is larger than that of the graphite material. Therefore, according to the nonaqueous electrolyte secondary battery of the present invention, the battery capacity can be made larger than that of the nonaqueous electrolyte secondary battery using the negative electrode active material made of only the graphite material.

  Furthermore, the ratio of the Si oxide to the total amount of graphite and Si oxide is 1 part by mass or more and 20 parts by mass or less. If this ratio is less than 1 part by mass, a high capacity cannot be realized with Si oxide, and if it exceeds 20 parts by mass, expansion / contraction of the electrode plate is accompanied by expansion / contraction of the Si oxide. Increases and cycle characteristics deteriorate

Further, the positive electrode and the negative electrode are opposed to each other through the porous insulating layer to form a rolled electrode plate, the thickness of the porous insulating layer is A (μm), and the negative electrode composite facing from the surface of the positive electrode mixture layer is formed. When the distance between the electrodes to the surface of the agent layer is B (μm), the relationship between A and B satisfies the following formula 1.
(Formula 1) A ≦ B ≦ A × 1.3

  The distance (B) between the surface of the positive electrode mixture layer and the surface of the opposing negative electrode mixture layer is equal to or greater than the thickness of the porous insulating layer (A) and 1.3 times the thickness of the porous insulating layer When the following is set, a space is created between the positive electrode mixture layer and the porous insulating layer and between the negative electrode mixture layer and the porous insulating layer, and even if the Si oxide expands or contracts, it can be suppressed in this space. A non-aqueous electrolyte secondary battery excellent in the above can be obtained.

In addition, as a positive electrode active material which can be used in the nonaqueous electrolyte secondary battery of the present invention, a compound capable of reversibly occluding and releasing lithium ions can be used. As a compound capable of reversibly occluding and releasing lithium ions, for example, a lithium transition metal composite oxide represented by LiMO ₂ (where M is at least one of Co, Ni, and Mn) (Ie, LiCoO ₂ , LiNiO ₂ , LiNi _y Co _1-y O ₂ (y = 0.01 to 0.99), LiMnO ₂ , LiCo _x Mn _y Ni _z O ₂ (x + y + z = 1), etc.), LiMn _One kind of ₂ O ₄ , LiFePO ₄ or the like, or a mixture of plural kinds thereof can be used. Further, a lithium cobalt composite oxide added with a different metal element such as zirconium, magnesium, or aluminum can be used.

  Examples of the non-aqueous solvent in the non-aqueous electrolyte that can be used in the non-aqueous electrolyte secondary battery of the present invention include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC); fluorine Cyclic carbonate ester; cyclic carboxylic acid ester such as γ-butyrolactone (γ-BL), γ-valerolactone (γ-VL); dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC) Chain carbonates such as methylpropyl carbonate (MPC) and dibutyl carbonate (DBC); fluorinated chain carbonates; chains such as methyl pivalate, ethyl pivalate, methyl isobutyrate, and methyl propionate Carboxylic acid ester; N, N′-dimethylform Bromide or, N- methyl oxazolidone amide compound, dimethylsulfoxide or the like; may be used tetrafluoroboric acid 1-ethyl-3- ambient temperature molten salt such as methyl imidazolium and the like; sulfur compounds such as sulfolane. Moreover, you may make it use these in mixture of 2 or more types.

As the electrolyte salt dissolved in the non-aqueous solvent in the non-aqueous electrolyte that can be used in the non-aqueous electrolyte secondary battery of the present invention, a lithium salt generally used as an electrolyte salt in the non-aqueous electrolyte secondary battery can be used. . Examples of such lithium salt include lithium hexafluorophosphate (LiPF ₆ ), LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN ( _{CF 3 SO 2) (C 4} F 9 SO 2), LiC (CF 3 SO 2) 3, LiC (C 2 F 5 SO 2) 3, LiAsF 6, LiClO 4, Li 2 B 10 Cl 10, Li 2 B ₁₂ Cl ₁₂ or the like can be used singly or as a mixture of a plurality of them. Among these, LiPF ₆ is particularly preferable. The amount of electrolyte salt dissolved in the non-aqueous solvent is preferably 0.8 to 1.5 mol / L.

  In the non-aqueous electrolyte solution of the non-aqueous electrolyte secondary battery of the present invention, as the electrode stabilizing compound, for example, vinylene carbonate (VC), vinyl ethyl carbonate (VEC), succinic anhydride (SUCAH), maleic anhydride Acid (MAAH), glycolic anhydride, ethylene sulfite (ES), divinyl sulfone (VS), vinyl acetate (VA), vinyl pivalate (VP), catechol carbonate, biphenyl (BP), etc. may be added. . Two or more of these compounds may be appropriately mixed and used.

  Hereinafter, the form for implementing this invention is demonstrated in detail using an experiment example. However, the following experimental examples are intended to embody the technical idea of the present invention, and are not intended to limit the present invention to these experimental examples. The present invention is shown in the claims. The present invention can be equally applied to various modifications without departing from the technical idea.

[Experimental Example 1]
First, a specific method for producing the nonaqueous electrolyte secondary battery according to Experimental Example 1 will be described.

[Production of positive electrode plate]
The positive electrode plate was produced as follows. First, nickel-lithium cobaltate (LiNi _0.82 Co _0.15 Al _0.03 O ₂ ) powder as a positive electrode active material, acetylene black as a positive electrode conductive agent, and polyvinylidene fluoride (PVdF) powder, A slurry was prepared by mixing the positive electrode active material: acetylene black: PVdF = 100: 1.25: 1.7 with an N-methyl-2-pyrrolidone (NMP) solution. This slurry was applied to both surfaces of a positive electrode current collector made of aluminum foil having a thickness of 15 μm by a doctor blade method and then dried to form a positive electrode mixture layer on both surfaces of the positive electrode current collector. Then, it compressed using the compression roller and cut | judged to thickness 0.177mm, width 58.5mm, and length 656mm, and produced the positive electrode plate.

[Production of negative electrode plate]
The negative electrode plate was produced as follows. First, particles having a composition of SiOx (x = 1) were pulverized and classified to adjust the particle size, and then the temperature was raised to about 1000 ° C., and the surfaces of the particles were coated with carbon by an CVD method in an argon atmosphere. And this was crushed and classified, and Si oxide represented as SiO was produced. In addition, the coating amount of carbon coated on the surface of SiO is 1 part by mass.

  Next, 96 parts by mass of graphite powder, 4 parts by mass of Si oxide, and 1 part by mass of a styrene butadiene rubber dispersion as a binder are dispersed in water, and the negative electrode is adjusted so that the solid content concentration is 60% by mass. The slurry was adjusted. This negative electrode slurry was applied to both surfaces of a negative electrode current collector made of copper foil having a thickness of 8 μm by a doctor blade method to form a negative electrode mixture layer. Next, after drying, the negative electrode active material density is compressed with a compression roller so as to be 1.65 g / cc, the thickness of the negative electrode mixture layer is adjusted, and the negative electrode plate is cut into a width of 59.5 mm and a length of 590 mm. Produced.

[Preparation of non-aqueous electrolyte]
5 parts by mass of vinylene carbonate (VC) is added to a mixed solvent composed of ethylene carbonate (EC) and dimethylmethyl carbonate (DMC) (volume ratio EC: DMC = 1: 3), and LiPF ₆ is added at 1 mol / A non-aqueous electrolyte was prepared by dissolving 1 liter.

[Preparation of electrode plate roll]
A positive electrode tab made of aluminum was attached to the core of the positive electrode plate, and a negative electrode tab made of nickel was attached to the core of the negative electrode plate. Using this positive electrode plate and negative electrode plate, a polyethylene porous insulating layer having a thickness of 16.0 μm was interposed between the two electrodes and wound into a cylindrical shape to obtain an electrode plate wound body.

Furthermore, the winding outer periphery of the electrode plate roll was fixed with a polypropylene adhesive tape.
When fixing the adhesive tape, the adhesive tape was affixed by shifting the position by 2 mm in the direction in which the electrode roll was loosened.

[Production of battery]
Insulating plates were arranged on the upper and lower end surfaces of the above electrode plate winding body, and housed inside a cylindrical bottomed cylindrical battery case having an inner diameter of 18.1 mm. Next, the negative electrode tab was welded to the bottom surface of the battery case, and the positive electrode tab was welded to the sealing body side having a safety valve that is operated by the internal pressure in the battery.

Next, the non-aqueous electrolyte was injected from the opening of the battery case by a reduced pressure method.
Next, a sealing body was disposed at the opening end of the battery case via a gasket, and the opening end of the battery case was sealed by caulking to produce a nonaqueous electrolyte secondary battery.
In this case, the distance between the electrodes on the surface of the negative electrode mixture layer facing the surface of the positive electrode mixture layer was 18.4 μm.

[Experiment 2]
The nonaqueous electrolyte secondary battery according to Experimental Example 2 was manufactured as follows. When preparing the electrode plate winding body in Experimental Example 1, when applying a tape to the electrode plate winding body at the end of winding, shift the electrode plate winding body by 1 mm in the loosening direction, and loosen the tension rate of the electrode plate winding body, A nonaqueous electrolyte secondary battery according to Experimental Example 2 was produced in the same manner as in Experimental Example 1 except that the electrode plate winding body was housed in a battery case having an inner diameter of 17.9 mm.
In addition, the distance between the electrodes on the surface of the negative electrode mixture layer facing the surface of the positive electrode mixture layer in Experimental Example 2 was 16.0 μm.

[Experiment 3]
The nonaqueous electrolyte secondary battery according to Experimental Example 3 was manufactured as follows. In the production of the electrode plate winding body in Experimental Example 1, when the end-of-winding tape is applied to the electrode plate winding body, the electrode plate winding body is shifted by 3 mm in the loosening direction to loosen the tension rate of the electrode plate winding body, A nonaqueous electrolyte secondary battery according to Experimental Example 3 was manufactured in the same manner as in Experimental Example 1 except that the electrode plate wound body was housed in a 18.3 mm battery case.
In addition, the distance between the electrodes on the surface of the negative electrode mixture layer opposite to the surface of the positive electrode mixture layer in Experimental Example 3 was 20.8 μm.

[Experimental Example 4]
The nonaqueous electrolyte secondary battery according to Experimental Example 4 was produced as follows. In the production of the electrode plate winding body in Experimental Example 1, when using a separator having a thickness of 14.1 μm and applying a tape at the end of winding to the electrode plate winding body, the electrode plate winding body is shifted by 1 mm in the loosening direction. The nonaqueous electrolyte secondary battery according to Experimental Example 4 was prepared in the same manner as in Experimental Example 1, except that the tightness of the wound body was relaxed and the electrode plate wound body was housed in a battery case having an inner diameter of 17.7 mm. Produced.
In addition, the distance between the electrodes on the surface of the negative electrode mixture layer facing the surface of the positive electrode mixture layer in Experimental Example 4 was 14.1 μm.

[Experimental Example 5]
The nonaqueous electrolyte secondary battery according to Experimental Example 5 was produced as follows. In the production of the electrode plate winding body in Experimental Example 1, when using a separator having a thickness of 14.1 μm and applying the tape to the end of the electrode plate winding, the electrode plate winding body is shifted by 2 mm in the loosening direction. The non-aqueous electrolyte secondary battery according to Experimental Example 5 was obtained in the same manner as in Experimental Example 1 except that the tightness of the wound body was relaxed and the electrode plate wound body was housed in a battery case having an inner diameter of 17.9 mm. Produced.
The inter-electrode distance between the surface of the negative electrode mixture layer facing the surface of the positive electrode mixture layer in Experimental Example 5 was 16.2 μm.

[Experimental Example 6]
The nonaqueous electrolyte secondary battery according to Experimental Example 6 was produced as follows. In the production of the electrode plate winding body in Experimental Example 1, when using a separator with a thickness of 14.1 μm and applying the tape to the end of the electrode plate winding, the electrode plate winding body is shifted by 3 mm in the loosening direction. The non-aqueous electrolyte secondary battery according to Experimental Example 6 was manufactured in the same manner as in Experimental Example 1 except that the tightness of the wound body was relaxed and the electrode plate wound body was housed in a battery case having an inner diameter of 18.1 mm. Produced.
In addition, the distance between the electrodes on the surface of the negative electrode mixture layer opposite to the surface of the positive electrode mixture layer in Experimental Example 6 was 18.3 μm.

[Experimental Example 7]
The nonaqueous electrolyte secondary battery according to Experimental Example 7 was produced as follows. In the production of the electrode plate winding body in Experimental Example 1, when using a separator having a thickness of 19.6 μm and applying a tape to the end of the electrode plate winding, the electrode plate winding body is shifted by 3 mm in the loosening direction. The non-aqueous electrolyte secondary battery according to Experimental Example 7 is the same as in Experimental Example 1 except that the tightness of the wound body is relaxed and the electrode plate wound body is housed in a battery case having an inner diameter of 18.4 mm. Produced.
In addition, the distance between the electrodes of the negative electrode mixture layer surface facing the positive electrode mixture layer surface in this experimental example 7 was 22.5 μm.

[Experimental Example 8]
The nonaqueous electrolyte secondary battery according to Experimental Example 8 was produced as follows. In preparation of the negative electrode plate in Experimental Example 1, 99 parts by mass of graphite powder and 1 part by mass of Si oxide were used, except that the capacity per unit area of the negative electrode was made equal to that of Experimental Example 1. In the same manner as in the case, a nonaqueous electrolyte secondary battery according to Experimental Example 8 was produced.
In addition, the inter-electrode distance between the surface of the negative electrode mixture layer facing the surface of the positive electrode mixture layer in Experimental Example 8 was 18.3 μm.

[Experimental Example 9]
The nonaqueous electrolyte secondary battery according to Experimental Example 9 was produced as follows. In preparation of the negative electrode plate in Experimental Example 1, 80 parts by mass of graphite powder and 20 parts by mass of Si oxide were used, except that the capacity per unit area of the negative electrode was made equal to that of Experimental Example 1. A nonaqueous electrolyte secondary battery according to Experimental Example 9 was produced in the same manner as in the case.
In addition, the inter-electrode distance between the surface of the negative electrode mixture layer facing the surface of the positive electrode mixture layer in Experimental Example 9 was 18.6 μm.

[Experimental Example 10]
The nonaqueous electrolyte secondary battery according to Experimental Example 10 was produced as follows. In the production of the electrode plate winding body in Experimental Example 1, when the end-of-winding tape was applied to the electrode plate winding body, the end-of-winding tape was applied without shifting, and the electrode plate winding body was stored in a battery case having an inner diameter of 17.8 mm. A nonaqueous electrolyte secondary battery according to Experimental Example 10 was fabricated in the same manner as in Experimental Example 1 except that this was done.
In addition, the distance between the electrodes on the surface of the negative electrode mixture layer facing the surface of the positive electrode mixture layer in Experimental Example 10 was 14.6 μm.

[Experimental Example 11]
The nonaqueous electrolyte secondary battery according to Experimental Example 11 was produced as follows. In the production of the electrode plate winding body in Experimental Example 1, when the end of winding is applied to the electrode plate winding body, the electrode plate winding body is shifted by 5 mm in the loosening direction, the tension rate of the electrode plate winding body is relaxed, and the inner diameter A nonaqueous electrolyte secondary battery according to Experimental Example 11 was fabricated in the same manner as in Experimental Example 1 except that the electrode plate wound body was housed in a 18.4 mm battery case.
In addition, the distance between the electrodes of the negative electrode mixture layer surface facing the positive electrode mixture layer surface in Experimental Example 11 was 22.7 μm.

[Experimental example 12]
The nonaqueous electrolyte secondary battery according to Experimental Example 12 was produced as follows. In the production of the negative electrode plate in Experimental Example 1, the experimental example is the same as in Experimental Example 1, except that the graphite powder is 100 parts by mass and the capacity per unit area of the negative electrode is made equal to that of Experimental Example 1. A non-aqueous electrolyte secondary battery according to No. 12 was produced.
The interelectrode distance between the surface of the negative electrode mixture layer facing the surface of the positive electrode mixture layer in Experimental Example 12 was 18.4 μm.

[Experimental Example 13]
The nonaqueous electrolyte secondary battery according to Experimental Example 13 was produced as follows. In the production of the negative electrode plate in Experimental Example 1, 75 parts by mass of graphite powder and 25 parts by mass of Si oxide were used, except that the capacity per unit area of the negative electrode was made equal to that of Experimental Example 1. In the same manner as in the case, a nonaqueous electrolyte secondary battery according to Experimental Example 13 was produced.
In addition, the distance between the electrodes on the surface of the negative electrode mixture layer facing the surface of the positive electrode mixture layer in Experimental Example 13 was 18.3 μm.

[Measurement of capacity retention after 500 cycles]
Regarding the nonaqueous electrolyte secondary batteries according to Experimental Examples 1 to 13, the capacity retention rate after 500 cycles was performed as cycle characteristics as follows. Each non-aqueous electrolyte secondary battery was charged at 25 ° C. with a constant current of 0.5 It = 1700 mA until the battery voltage reached 4.2 V, and then at a constant voltage of 4.2 V, the current was 0.01 It = 34 mA. Then, the battery was charged until it converged, and then discharged at a constant current of 1 It = 3400 mA until the battery voltage reached 2.5 V, which was defined as one cycle. Then, the discharge capacity at the first cycle and the discharge capacity at the 500th cycle were measured, and the capacity retention ratio after 500 cycles was calculated as follows. The results are shown in Table 1.
Capacity maintenance rate after 500 cycles (%)
= (Discharge capacity at 500th cycle / discharge capacity at the first cycle) × 100

From the results shown in Table 1, the following can be understood.
Examples 1 to 9 in which the content of Si oxide is 1 to 20 parts by mass and the distance (B) between the positive and negative electrode plates satisfies A ≦ B ≦ A × 1.3 are negative electrodes expanded during charging. Since the electrolyte solution is not pushed out of the electrode plate wound body from the mixture layer, an excellent capacity retention ratio is obtained.

  Further, in Experimental Example 12 in which the content of Si oxide is less than 1 part by mass, the capacity cannot be satisfied, and in Experimental Example 13 in which the content exceeds 20 parts by mass, the expansion and contraction of Si oxide is further increased. Even when the distance (B) between the positive and negative electrode plates is in the range of A ≦ B ≦ A × 1.3, an excellent capacity retention rate is not obtained.

Further, in Experimental Example 10 in which the distance between the positive and negative electrode plates (B) is shorter than that of (A), the electrolyte solution is pushed out of the electrode plate wound body from the negative electrode mixture layer expanded during charging. Capacity maintenance rate is decreasing.
Further, in Experimental Example 11 in which the distance between the positive and negative electrode plates (B) is longer than (A × 1.3), the internal resistance of the electrode plate winding body is increased, so that the capacity maintenance ratio is reduced. .

Claims (1)

A positive electrode including a positive electrode mixture layer including a positive electrode active material, a negative electrode including a negative electrode mixture layer including a negative electrode active material, a porous insulating layer, and a nonaqueous electrolyte in which a lithium salt is dissolved in a nonaqueous solvent. A non-aqueous electrolyte secondary battery comprising:
The negative electrode active material contains graphite and Si oxide containing Si and O as constituent elements (however, the atomic ratio x of O with respect to the total amount of Si is 0.5 ≦ x ≦ 1.5),
The ratio of the Si oxide to the total amount of the graphite and the Si oxide is 1 part by mass or more and 20 parts by mass or less,
The positive electrode and the negative electrode are opposed to each other through the porous insulating layer, and the electrode plate winding body is formed. The thickness of the porous insulating layer is A (μm), and the positive electrode mixture layer is opposed to the surface. A nonaqueous electrolyte secondary battery in which the relationship between A and B satisfies the following formula 1 when the interelectrode distance to the surface of the negative electrode mixture layer is B (μm).
(Formula 1) A ≦ B ≦ A × 1.3