JP2000173650A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a nonaqueous electrolyte secondary battery superior in stability, a load characteristic and a cycle characteristic. SOLUTION: This nonaqueous electrolyte battery has a positive electrode 1, a negative electrode 2 containing graphite, and a nonaqueous solvent type electrolytic solution 4. A constituent solvent of the electrolytic solution 4 contains a phosphate ester in a volume ratio of 15% or higher, while the electrolytic solution 4 contains an organic compound A, including both an aromatic group and a carbonyl group without interposition of an oxygen atom. The electrolytic solution 4 preferably contains the organic compound A in a content per unit area of the negative electrode 2 of 0.1 μL/cm2 or higher, and in a volume ratio of 15% or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly, to a non-aqueous electrolyte secondary battery having high safety and excellent load characteristics and cycle characteristics.

[0002]

2. Description of the Related Art Non-aqueous electrolyte secondary batteries represented by lithium secondary batteries have high capacity, high voltage and high energy density, and therefore, great expectations are placed on their development. .

[0003] Incidentally, the above non-aqueous electrolyte secondary battery uses an organic solvent such as ether, ester, or carbonate as a constituent solvent of the electrolyte. When exposed to high temperatures,
The vapor pressure of the organic solvent increases in the battery, and the solvent vapor that has reached the flash point is released to the outside by the operation of the cleavage vent and comes into contact with the outside air, which may cause ignition or ignition. In addition, the above-described problem also occurs due to an internal short circuit, and the internal temperature of the battery increases due to the short circuit, which may result in ignition or ignition.

[0004]

In order to solve such a problem, attempts have been made to make the electrolytic solution flame-retardant by using a flame-retardant solvent as a constituent solvent of the electrolytic solution. It has been proposed to use a phosphoric acid ester as a constituent solvent of an electrolytic solution (JP-A-4-184870).

By the way, graphite, which can be expected to have a high capacity, has been widely used as an active material of a negative electrode of a non-aqueous electrolyte secondary battery. However, a negative electrode using this graphite as a constituent material has been described above. When used in a phosphate-based electrolyte,
The electrolytic solution is decomposed and generates a larger amount of gas than the conventional electrolytic solution during chemical formation or heating.Therefore, the current interrupt mechanism may operate during normal use. There has been a problem that the deposited film has a bad influence on battery characteristics, such as lowering load characteristics and lowering initial charge / discharge efficiency.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a non-aqueous electrolyte secondary battery using graphite as one of the constituent materials of a negative electrode as described above. It is an object of the present invention to provide a non-aqueous electrolyte secondary battery that solves the problems caused when an ester is used, has high safety, and has excellent load characteristics and cycle characteristics.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a non-aqueous electrolyte secondary battery using graphite as one of the constituent materials of a negative electrode. When used as, the above-mentioned problem is solved by incorporating an organic compound A having both an aromatic ring and a carbonyl group without interposing an oxygen atom in the electrolytic solution, so that the safety is high, and the load characteristics and cycle are improved. It is intended to obtain a non-aqueous electrolyte secondary battery having excellent characteristics.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, as described above, the organic compound A having both an aromatic group and a carbonyl group is contained in the electrolytic solution without interposing an oxygen atom, thereby providing load characteristics and cycle characteristics. Improve characteristics. The reason why the load characteristics and cycle characteristics can be improved in this way is not always clear at present, but when the organic compound A is contained in the electrolytic solution,
It is considered that the organic compound A is preferentially decomposed on the surface of the negative electrode in the early stage of charging to form a film on the surface of the negative electrode, thereby suppressing the subsequent decomposition of the phosphate ester. Further, since the organic compound A needs to be preferentially decomposed on the surface of the negative electrode as described above, it can be reduced at a potential of 0.8 V or more with respect to metal Li on the surface of the negative electrode. Is preferred. The content of the organic compound A in the electrolyte is 0.1% per unit area of the negative electrode.
It is preferably at least μL / cm ² . In order to maintain the flame retardancy of the electrolytic solution, the content of the organic compound A in the electrolytic solution is preferably 15% or less by volume. The L in μL / cm ² means liter, but for the purpose of avoiding misunderstanding in the present specification, the unit of the content of the organic compound A is not represented by lower case “l”, but by upper case. "L" is used.

The aromatic group of the organic compound A is considered to have an effect of enhancing the affinity with the graphite surface by its pi-electron conjugated system. In particular, a six-membered carbon ring such as a phenyl group or a naphthyl group serves as a basic skeleton. Are preferred because of their high affinity. On the other hand, examples of the carbonyl group of the organic compound A include those present in the form of ketone, diketone, ester, perester, and the like. Particularly, those present in the form of ester and perester are preferable. Having an aromatic group (that is, the aromatic group is directly added to the carbonyl group or adjacent to the carbonyl group via one atom). The reason why such a structure produces a good result is not always clear at present, but it is speculated that the above structure has an effect of increasing the reactivity of the carbonyl group and favorably promoting the formation of a film. In addition, the organic compound A
Requires that a carbonyl group and an aromatic group be bonded together without an oxygen atom between them, but if an oxygen atom is interposed, This is presumed to be due to the separation of the group group and the carbonyl group.

Preferable specific examples of the organic compound A include, for example, benzoyl peroxide [C ₆ H ₅ -C
OO-OCO-C ₆ H _5], phenylethyl acetate _{[C 6 H 5 · CH 2 ·} COOCH 2 CH 3 ], benzoic acid ethyl ester _{[C 6 H 5 · COOCH 2 CH} 3 ], and the like.

As the organic compound A, a plurality of different substances can be used at the same time. In this case, the total amount thereof is 0.1 μL / cm ² or more per unit area of the negative electrode.
It is preferable that the volume ratio be 15% or less in the electrolytic solution.

Further, in the present invention, the phosphoric acid ester in the constituent solvent of the electrolytic solution is specified to be at least 15% by volume, but this is difficult to obtain high safety against ignition and ignition. This is because the phosphoric acid ester, which is a flammable solvent, requires 15% or more by volume, preferably 30% or more by volume, more preferably 50% or more by volume, and still more preferably 70% or more by volume. , More preferably at least 85% by volume. However, if the proportion of the phosphoric acid ester in the electrolytic solution is too large, the charge and discharge of graphite as the negative electrode active material may be hindered. It is more preferably at most 80%. In order to ensure sufficient flame retardancy for this phosphate ester,
Preferably, 80% or more by volume of the phosphate ester has 6 or less carbon atoms, and more preferably 4 or less carbon atoms. It is preferable to use a mixture of at least two kinds of the cyclic phosphate and the non-cyclic phosphate, as compared with using one kind of the phosphoric acid ester, because the load characteristics are improved.

Examples of the cyclic phosphate include methyl ethylene phosphate, ethyl ethylene phosphate, methyl neopentyl phosphate, and the like.
Trimethyl phosphate, triethyl phosphate and the like. Further, as the above-mentioned phosphoric acid ester, those having a halogenated alkyl group, an unsaturated hydrocarbon group, a carboxylic acid ester group, a carbonic acid ester group or the like in the structure can be used.

These phosphate esters can be used alone or in combination of two or more, regardless of whether they are cyclic or non-cyclic. Since the load characteristics can be improved by using a mixture of the phosphate ester and the phosphate ester, particularly when the phosphate ester occupies 70% or more by volume in the constituent solvent of the electrolytic solution, the cyclic phosphate ester and the non-cyclic ester are used. It is preferable to include two or more types with a phosphoric acid ester. This is because the cyclic phosphate ester exhibits a high dielectric constant and the acyclic phosphate ester exhibits a low viscosity to improve load characteristics. Then, the ratio of the cyclic phosphate to the non-cyclic phosphate is 5:95 to 50:50 by volume.
50 is preferred.

The electrolytic solution is constituted by dissolving the electrolyte in the electrolyte solvent. However, since the volume of the electrolyte at the time of dissolution is very small compared to the volume of the electrolyte solvent, the volume of the electrolyte is substantially reduced. It can be considered to be the same as the volume of the solvent.

In the electrolyte of the present invention, in addition to the essential constituent solvents described above, for example, 1,2-dimethoxyethane, 1,2-diethoxyethane, propylene carbonate, ethylene carbonate, γ-butyrolactone, Tetrahydrofuran, 1,3-dioxolane, diethylene carbonate, dimethyl carbonate, ethylmethyl carbonate, 4,5-dimethyl-1,3-dioxol-2
For example, -one (DMDO) can be used as a constituent solvent of the electrolytic solution. In addition to the phosphoric acid ester, a phosphazene derivative, a silane, a halide of an ether or an ester, and the like, which can be expected to have an effect as a flame retardant solvent, can be used as appropriate.

As the electrolyte, for example, LiClO_Four,
LiPF₆, LiBF_Four, LiAsF₆, LiSb
F₆, LiCF_ThreeSO_Three, LiC_FourF₉SO_Three, LiC
F_ThreeCO _Two, Li_TwoC_TwoF_Four(SO_Three)_Two, LiN (C
F_ThreeSO_Two)_Two, LiC (CF_ThreeSO_Two)_Three, LiC_n
F_{2n + 1}SO_Three(N ≧ 2), LiN (RfOSO_Two)
_Two[Where Rf is a fluoroalkyl group]
Or two or more kinds, but especially LiPF₆And
LiC_FourF₉SO_ThreeAre preferred. In the electrolyte
The concentration of the electrolyte is not particularly limited.
If the amount is over 1 mol, the safety is further improved
And more preferably 1.2 mol / l or more.
The concentration of the electrolyte in the electrolyte was 1.7 mol /
When the value is 1 or less, electric characteristics are improved.
It is more preferably at most 5 mol / l.

In the present invention, as the positive electrode active material, for example, lithium cobalt oxide such as LiCoO ₂ ;
lithium nickel oxide such as iNiO ₂ , LiMn ₂
Lithium manganese oxides such as O ₄ , lithium titanium oxides such as LiTiO ₂ , and metals such as Li (NiCo) O ₂ in which a part of Ni of LiNiO ₂ is replaced by Co, manganese dioxide, vanadium pentoxide, and chromium oxide Oxides or metal sulfides such as titanium disulfide and molybdenum disulfide are used. Among them, LiNiO ₂ , Li
The open circuit voltage during charging of NiO ₂ , LiMn ₂ O _4, etc. is L
A lithium composite oxide exhibiting 4 V or more on an i basis is preferable because a high energy density can be obtained. In addition, when a thermally unstable lithium nickel oxide such as LiNiO ₂ or a composite oxide containing nickel is used as the positive electrode active material, the present invention is applied to make the electrolytic solution flame-retardant. Safety can be ensured.

The positive electrode is made of, for example, a conductive auxiliary such as flake graphite or carbon black, if necessary, polyvinylidene fluoride, polytetrafluoroethylene, ethylene propylene diene rubber, or polyacrylic. An acid and a binder such as carboxymethyl cellulose are added and mixed to prepare a positive electrode mixture, which is dissolved or dispersed in water or a solvent to form a paste (the binder is dissolved in a solvent or the like in advance, and then mixed with the positive electrode active material, etc.). The positive electrode mixture-containing paste may be applied to a current collector made of aluminum foil or the like, dried, and subjected to a step of forming a positive electrode mixture layer on at least one surface of the current collector. Produced by However, the method for producing the positive electrode is not limited to the method described above, but may be another method.

As described above, graphite is used as the active material of the negative electrode. Examples of the graphite include natural graphite and artificial graphite obtained by firing organic compounds.

The negative electrode may be, for example, a conductive auxiliary such as flake graphite, carbon black, etc., if necessary, polyvinylidene fluoride, polytetrafluoroethylene, ethylene propylene diene rubber, or polyacrylic. An acid and a binder such as carboxymethylcellulose are added and mixed to prepare a negative electrode mixture, which is dissolved or dispersed in water or a solvent to form a paste (the binder is first dissolved in a solvent or the like, and then the negative electrode active material is prepared). The negative electrode mixture-containing paste may be applied to a current collector made of copper foil or the like, and dried.
The current collector is manufactured through a step of forming a negative electrode mixture layer on at least one surface of the current collector. However, the method for producing the negative electrode is not limited to the method exemplified above, and may be another method. The amount of the binder is not particularly limited, but is preferably 1 to 50% by weight, more preferably 2 to 20% by weight, based on the active material.

As the current collector for the positive electrode and the negative electrode, for example, a metal foil such as aluminum, copper, nickel, and stainless steel, or a mesh of such a metal is used. Aluminum foil is particularly suitable, and copper foil is particularly suitable as the negative electrode current collector.

Any separator may be used as long as it has sufficient strength and can hold a large amount of electrolyte. From such a viewpoint, the thickness is 10 to 50 μm and the porosity is 30 to 70 μm.
% Of polyethylene, polypropylene, or a copolymer of ethylene and propylene.

The battery is, for example, a spirally wound electrode body or a laminated electrode body such as a spirally wound electrode body produced by spirally winding a separator between the positive electrode and the negative electrode produced as described above. Is inserted into a nickel-plated iron or stainless steel battery case and sealed. Further, the battery usually incorporates an explosion-proof mechanism for discharging the gas generated inside the battery to the outside of the battery when the pressure has risen to a certain pressure, thereby preventing the battery from bursting under high pressure.

[0025]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only these examples.

Example 1 Trimethyl phosphate and 4,5-dimethyl-1,3
-Dioxol-2-one and benzoyl peroxide as the organic compound A are mixed in a volume ratio of 84: 8: 8,
1.0 mol / l of LiPF ₆ was dissolved in the obtained mixed solvent to prepare a non-aqueous solvent-based electrolyte containing an organic solvent as a main constituent solvent.

Also, 91 parts by weight of LiCoO ₂ (lithium cobalt oxide), 6 parts by weight of graphite and 3 parts by weight of polyvinylidene fluoride were added, mixed and dispersed with N-methylpyrrolidone to prepare a paste. This positive electrode mixture-containing paste is uniformly applied to both surfaces of a positive electrode current collector made of aluminum foil having a thickness of 20 μm, dried to form a positive electrode mixture layer, and then compression-molded with a roller press to form a lead body. Welding was performed to produce a belt-shaped positive electrode.

Apart from the above, the surface distance (d ₀₀₂ ) is about 0.
90 parts by weight of 336 nm flaky graphite [KS-15 (trade name, manufactured by Lonza)] and 10 parts by weight of polyvinylidene fluoride were mixed to prepare a negative electrode mixture, which was dispersed with N-methylpyrrolidone to prepare a paste. did. This negative electrode mixture-containing paste is uniformly applied to both surfaces of a negative electrode current collector made of copper foil having a thickness of 18 μm, dried to form a negative electrode mixture layer, and then compression-molded with a roller press to form a lead body. Do the welding,
A strip-shaped negative electrode was produced. The formation area of the negative electrode mixture layer of the negative electrode was 260 cm ² on both sides, and the amount of benzoyl peroxide per unit area of the negative electrode (however, the unit area of the negative electrode mixture layer forming portion) was 0.48 μL / cm ² . there were.

The strip-shaped positive electrode is superposed on the strip-shaped negative electrode via a separator made of a microporous polyethylene film having a thickness of 25 μm, and spirally wound to form a spiral electrode body. The battery was filled in a cylindrical battery case, and the positive and negative electrode leads were welded. Next, 1.6 ml of the electrolytic solution was poured into the battery case, and after the electrolytic solution had sufficiently penetrated into the separator and the like, sealing, preliminary charging and aging were performed, and the structure as shown in the schematic diagram of FIG. 1 was obtained. A cylindrical non-aqueous electrolyte secondary battery was manufactured.

Referring to the battery shown in FIG. 1, reference numeral 1 denotes the positive electrode and reference numeral 2 denotes the negative electrode. In FIG. 1, in order to avoid complication, the current collector and the negative electrode used for producing the positive electrode 1 and the negative electrode 2 are used. A metal foil or the like as a base is not shown.
The positive electrode 1 and the negative electrode 2 are spirally wound with a separator 3 interposed therebetween, and are housed in a battery case 5 together with the electrolytic solution 4 as a spiral electrode body.

The battery case 5 is made of stainless steel, and an insulator 6 made of polypropylene is arranged at the bottom of the battery case 5 before the spiral electrode body is inserted. The sealing plate 7 is made of aluminum and is in the shape of a disk.
And a hole as a pressure introduction port 7b for allowing the battery internal pressure to act on the explosion-proof valve 9 is provided around the thin portion 7a. An explosion-proof valve 9 is provided on the upper surface of the thin portion 7a.
Are welded to form a welded portion 11. In addition, the thin portion 7a provided on the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 are illustrated only in a cut plane so as to be easily understood in the drawings, and a contour line behind the cut plane is shown. Is not shown. Further, the welded portion 11 between the thin portion 7a of the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 is shown in an exaggerated state rather than the actual one so as to be easily understood in the drawings.

The terminal plate 8 is made of rolled steel, has a nickel-plated surface, and has a hat-like shape with a brim at the periphery. The terminal plate 8 is provided with a gas outlet 8a. . The explosion-proof valve 9 is made of aluminum and has a disk shape.
In the center thereof, a protruding portion 9a having a tip portion is provided on the power generation element side (the lower side in FIG. 1), and a thin portion 9b is provided, and the lower surface of the protruding portion 9a is, as described above, It is welded to the upper surface of the thin portion 7a of the sealing plate 7 to form a welded portion 11. The insulating packing 10 is made of polypropylene and has an annular shape. The insulating packing 10 is disposed above the peripheral portion of the sealing plate 7, and the explosion-proof valve 9 is disposed above the insulating packing 10, and insulates the sealing plate 7 from the explosion-proof valve 9. The gap between the two is sealed so that the electrolyte does not leak from between the two. The annular gasket 12 is made of polypropylene, and the lead body 13 is made of aluminum. The sealing plate 7 and the positive electrode 1 are connected to each other. An insulator 14 is disposed above the spiral electrode body. The bottom portion is connected by a lead body 15 made of nickel.

In this battery, the thin portion 7 of the sealing plate 7
a and the explosion-proof valve 9a come into contact at the welded portion 11, and the explosion-proof valve 9a
And the peripheral edge of the terminal plate 8 are in contact with each other, and the positive electrode 1 and the sealing plate 7 are connected by the lead 13 on the positive electrode side.
The positive electrode 1 and the terminal plate 8 are electrically connected to each other by the lead body 13, the sealing plate 7, the explosion-proof valve 9, and their welded portions 11, and function normally as an electric circuit.

When an abnormal situation occurs in the battery and gas is generated inside the battery and the internal pressure of the battery rises, the internal pressure rises and the central part of the explosion-proof valve 9 moves in the internal pressure direction (FIG. 1).
Then, it is deformed in the upper direction)
The shearing force acts on the thin portion 7a integrated at 1 and the thin portion 7a is broken or the projection 9a of the explosion-proof valve 9 is formed.
And the thin portion 7a of the sealing plate 7 is peeled off, whereby the electrical connection between the positive electrode 1 and the terminal plate 8 is lost and the current is cut off. As a result, the battery reaction does not proceed, so even during overcharge or short circuit, the battery temperature and internal pressure rise due to the charging current and short circuit current do not progress further, preventing the battery from bursting under high pressure Designed to be able to.

Example 2 A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1 except that phenylacetic acid ethyl ester was used instead of benzoyl peroxide in the non-aqueous electrolyte secondary battery of Example 1. Produced.

Comparative Example 1 In place of the electrolyte in the nonaqueous electrolyte secondary battery of Example 1, trimethyl phosphate and 4,5-dimethyl-
LiPF ₆ was added at 1 mol / l to a mixed solvent obtained by mixing 1,3-dioxol-2-one in a volume ratio of 92: 8.
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1, except that the electrolyte prepared by dissolution was used.

Comparative Example 2 The procedure of Example 1 was repeated except that benzoyl peroxide in the nonaqueous electrolyte secondary battery of Example 1 was replaced by phenyl acetate having an oxygen atom between an aromatic group and a carbonyl group. A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1.

Examples 1-2 produced as described above
The batteries of Comparative Examples 1 and 2 were subjected to a flammability test and a charge / discharge test. The test method and test results are shown below.

[Flammability Test] With respect to the batteries of Examples 1 and 2 and Comparative Examples 1 and 2, the batteries were heated to a high temperature and the safety valve was operated [that is, in the battery shown in FIG. When a gas is generated inside the battery due to evaporation of the solvent and the internal pressure of the battery rises and reaches a predetermined pressure, the internal pressure rises so that the central portion of the explosion-proof valve 9 moves in the direction of the internal pressure (in FIG. ), A shearing force acts on the thin portion 7a integrated at the welded portion 11 to break the thin portion 7a, or the protrusion 9a of the explosion-proof valve 9 and the sealing plate 7 In the state where the gas inside the battery is discharged from the gas discharge port 8a of the terminal plate 8 to the outside of the battery]. Disassemble the sealing part to expose the inside of the battery Advance, the battery in the state 10
The mixture was heated to 0 ° C., and a fire was brought close to the exposed portion to determine whether or not it ignited. Table 1 shows the results.

[0040]

[Table 1]

As is clear from the results of the flammability test shown in Table 1, the batteries of Examples 1 and 2 did not ignite even when heated to 100 ° C., as did the batteries of Comparative Examples 1 and 2. Had high security against

[Charge / Discharge Test] The batteries of Examples 1 and 2 and Comparative Examples 1 and 2 were charged and discharged in a voltage range of 2.75 to 4.2 V, and the initial charge / discharge efficiency [(discharge capacity / charge capacity) ) × 100] and the discharge capacity ratio at a current density of 1 C and 0.1 C. The above discharge capacity ratio [(discharge capacity at 1 C) / (discharge capacity at 0.1)] is defined as the load characteristic (1 C /
0.1C) "in Table 2 together with the initial charge / discharge efficiency.

[0043]

[Table 2]

As shown in Table 2, the batteries of Examples 1 and 2 had higher initial charge / discharge efficiency and better load characteristics than the batteries of Comparative Examples 1 and 2. That is, according to the present invention, it is clear that the initial charge / discharge efficiency can be improved, the cycle characteristics can be improved, and the load characteristics can be improved.

On the other hand, in the battery of Comparative Example 1, the decomposition of the electrolytic solution using the phosphate ester as a constituent solvent occurred, and a large amount of irreversible charge capacity was generated, resulting in poor initial charge / discharge efficiency. It is considered that the load characteristics deteriorated because the film formed on the surface of the negative electrode due to the decomposition of the electrolytic solution hindered the electrode reaction. Further, in the battery of Comparative Example 2, the phenyl acetate acetate contained in the electrolytic solution had a structure in which an oxygen atom was interposed between the aromatic group and the carbonyl group, so that decomposition occurred, thereby decomposing the electrolytic solution. However, the initial charge / discharge efficiency decreases as in the battery of Comparative Example 1,
It is considered that the load characteristics deteriorated. However, in the battery of the present invention, benzoyl peroxide and phenylacetic acid ethyl ester belonging to the organic compound A did not cause decomposition of the electrolytic solution as in the batteries of Comparative Examples 1 and 2, and as a result, It is considered that the initial charge / discharge efficiency was high and the load characteristics were excellent.

[0046]

As described above, according to the present invention, a non-aqueous electrolyte secondary battery having high safety and excellent cycle characteristics and load characteristics can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing one example of a non-aqueous electrolyte secondary battery according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4 Electrolyte

Claims (6)

[Claims] 1. A non-aqueous electrolyte secondary battery having a positive electrode, a graphite-containing negative electrode and a non-aqueous solvent-based electrolyte, wherein a phosphate ester is contained in a solvent of the electrolyte in a volume ratio of 15%.
% Or more and an organic compound A having both an aromatic group and a carbonyl group without intervening oxygen atoms in the electrolytic solution. 2. The organic compound A content in the electrolytic solution is 0.1 μL / cm ² or more per unit area of the negative electrode, and the volume ratio of the organic compound A in the electrolytic solution is 15% or less. The non-aqueous electrolyte secondary battery according to claim 1. 3. The non-aqueous electrolyte secondary battery according to claim 1, wherein an aromatic group is added to the α-position or the β-position of the carbonyl group of the organic compound A in the electrolyte. 4. The non-aqueous electrolysis according to claim 1, wherein the organic compound A in the electrolytic solution can be decomposed on the negative electrode at a potential of 0.8 V or more with respect to metal Li. Liquid secondary battery. 5. The non-aqueous electrolyte secondary according to claim 1, wherein the organic compound A in the electrolyte is an ester or a perester (CO—O—O—CO). battery. 6. The non-aqueous electrolyte secondary battery according to claim 1, wherein the phosphate in the electrolyte is trimethyl phosphate, and the content thereof is 30% or more by volume.