Non-aqueous electrolyte and energy device

Abstract

To provide a non-aqueous electrolyte that can suppress resistance to a higher level when used in a non-aqueous electrolyte battery.SOLUTION: A non-aqueous electrolyte solution containing a non-aqueous solvent and an electrolyte further includes a compound represented by the following formula (1), the electrolyte includes at least one specific anion-containing compound selected from the group consisting of anion-containing compounds having a P=O bond and a P-F bond, and anion-containing compounds having an S=O bond and an S-X bond, and X in the S-X bond is a heteroatom (in the formula (1), R is a hydrocarbon group having 5 to 10 carbon atoms).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a non-aqueous electrolyte and an energy device including the non-aqueous electrolyte.

Background Art

[0002] Non-aqueous electrolyte batteries such as lithium secondary batteries are being put into practical use in a wide range of applications, from so-called consumer power sources such as mobile phones and notebook computers to in-vehicle power sources for driving such as those for automobiles. However, in recent years, the demand for higher performance of non-aqueous electrolyte batteries has been increasing more and more. In particular, improvements in various battery characteristics such as high capacity, low-temperature use characteristics, high-temperature storage characteristics, cycle characteristics, and safety during overcharging are desired.

[0003] So far, as means for improving the high-temperature storage characteristics of non-aqueous electrolyte secondary batteries, numerous technologies have been studied for various battery components including the active materials of the positive and negative electrodes and the non-aqueous electrolyte.

[0004] For example, Patent Document 1 discloses an alkali metal electrochemical battery using a non-aqueous electrolyte in which nitrite ester is added to a non-aqueous electrolyte. Thereby, voltage delay is improved, and it is said that it can be suitably used for medical devices such as implantable pacemakers and defibrillators.

[0005] Patent Document 2 discloses that in a non-aqueous electrolyte secondary battery, when lithium difluorophosphate is added to a non-aqueous electrolyte, the high-temperature storage characteristics can be improved.

[0006] Patent Document 3 discloses that in a non-aqueous electrolyte secondary battery, when lithium fluorosulfonate is added to a non-aqueous electrolyte, the high-temperature storage characteristics can be improved.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

[0008] The inventor has found that the non-aqueous electrolytes or non-aqueous electrolytic solutions described in Patent Documents 1 to 3 have insufficient ionic conductivity in the interfacial protective film with the electrodes, that is, the film formed at the interface with the negative electrode and the conductive layer formed at the interface with the positive electrode, and there is room for improvement in terms of resistance suppression.

[0009] Therefore, an object of the present invention is to provide a non-aqueous electrolytic solution capable of suppressing resistance at a higher level when used in a non-aqueous electrolytic solution battery, and an energy device including the non-aqueous electrolytic solution. [Means for Solving the Problems]

[0010] In view of the above circumstances, the inventor has conducted intensive studies and as a result, has found that the above problems can be solved by using a non-aqueous electrolytic solution containing a specific nitrite compound and a specific anion-containing compound, and has completed the present invention.

[0011] That is, the gist of the present invention lies in the following. [1] A non-aqueous electrolytic solution containing a non-aqueous solvent and an electrolyte, wherein the non-aqueous electrolytic solution further contains a compound represented by the following formula (1), and the electrolyte contains at least one specific anion-containing compound selected from the group consisting of an anion-containing compound having a P=O bond and a P-F bond, and an anion-containing compound having an S=O bond and an S-X bond, where X in the S-X bond is a heteroatom, the non-aqueous electrolytic solution.

[0012] [Chemical Formula]

[0013] (In formula (1), R is a hydrocarbon group having 5 to 10 carbon atoms.)

[0014] [2] The non-aqueous electrolyte according to [1], wherein R in the formula (1) is a hydrocarbon group having 5 to 8 carbon atoms. [3] The non-aqueous electrolyte according to [1] or [2], wherein R in the formula (1) is an alkyl group. [4] The non-aqueous electrolyte according to any one of [1] to [3], wherein the content of the compound represented by the formula (1) in the non-aqueous electrolyte is 0.05% by mass or more and 1% by mass or less. [5] When the content of the compound represented by the formula (1) in the non-aqueous electrolyte is α% by mass and the content of the specific anion-containing compound is β% by mass, the non-aqueous electrolyte according to any one of [1] to [4], wherein the ratio of the contents represented by β / α is 0.01 or more and 100. [6] The non-aqueous electrolyte according to [5], wherein the ratio of the contents represented by β / α is 0.5 or more and 35 or less.

[0015] [7] An energy device including a negative electrode, a positive electrode, and a non-aqueous electrolyte, The non-aqueous electrolyte contains a non-aqueous solvent, an electrolyte, and a compound represented by the following formula (1), The electrolyte contains at least one specific anion-containing compound selected from the group consisting of an anion-containing compound having a P=O bond and a P-F bond, and an anion-containing compound having an S=O bond and an S-X bond, and X in the S-X bond is a heteroatom. Energy device.

[0016] [Chemical formula]

[0017] (In formula (1), R is a hydrocarbon group having 5 to 10 carbon atoms.)

[0018] [8] The negative electrode includes a current collector and a negative electrode active material layer formed on the current collector. The negative electrode active material layer contains at least one selected from the group consisting of silicon, simple metals, alloys and compounds thereof, tin, simple metals, alloys and compounds thereof, carbon-based materials, and lithium titanium composite oxides, in the energy device according to [7] above. [9] The positive electrode includes a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer contains at least one selected from the group consisting of lithium cobalt composite oxides, lithium cobalt nickel composite oxides, lithium manganese composite oxides, lithium cobalt manganese composite oxides, lithium nickel composite oxides, lithium nickel manganese composite oxides, and lithium cobalt nickel manganese composite oxides, in the energy device according to [7] or [8] above.

Effects of the Invention

[0019] According to the present invention, a non-aqueous electrolyte that suppresses the resistance of a battery after high-temperature storage at a higher level can be provided. Further, an energy device including the non-aqueous electrolyte can be provided.

Modes for Carrying Out the Invention

[0020] Hereinafter, modes for carrying out the present invention will be described in detail. However, the description given below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to these contents. Further, the present invention can be arbitrarily modified and implemented without departing from the gist thereof. In this specification, “~” is used in the sense of including the numerical values described before and after it as the lower limit value and the upper limit value.

[0021] 《1. Non-aqueous Electrolyte》 The non-aqueous electrolyte according to the present embodiment contains a non-aqueous solvent and an electrolyte, similar to a general non-aqueous electrolyte. The non-aqueous solvent dissolves the electrolyte. The non-aqueous electrolyte further contains a compound represented by the following formula (1). In formula (1), R is a hydrocarbon group having 5 to 10 carbon atoms.

[0022]

Chemical formula

[0023] Further, the electrolyte contains at least one specific anion-containing compound selected from the group consisting of an anion-containing compound having a P=O bond and a P-F bond, and an anion-containing compound having an S=O bond and an S-X bond (X: heteroatom).

[0024] The reason why the non-aqueous electrolyte according to this embodiment can exhibit an excellent effect of suppressing the resistance after high-temperature storage of the battery to a higher level is not clear, but the present inventor speculates as follows.

[0025] That is, it is considered that the compound represented by formula (1) forms a Li conduction layer having an N-O bond on the positive electrode surface by reacting with the active positive electrode during storage. On the other hand, it is considered that the specific anion-containing compound forms a Li conduction layer having a P-O bond or an S-O bond on the positive electrode surface by adsorption or partial reaction with the positive electrode during storage. In contrast, when the compound represented by formula (1) and the specific anion-containing compound coexist in the electrolyte, it is considered that a Li conduction layer containing both an N-O component and a P-O component and / or an S-O component is formed on the positive electrode. In the above Li conduction layer, it is considered that a part of the O bonded to P or S is substituted by N, resulting in the formation of P-N bonds or S-N bonds, and the structure is likely to be distorted. Therefore, the crystallinity is lower than that of the Li conduction layer formed when each compound is added alone, and the structure is likely to be distorted. As a result, the coordination with Li is weakened, and Li can easily move in the conduction layer. Therefore, it is considered that the positive electrode resistance after storage is preferably suppressed at a high level.

[0026] Regarding the negative electrode, the compound represented by formula (1) has a significant reductive decomposition reaction on the negative electrode, generating decomposition products having an N-O site and decomposition products having an R-O site. Among these, the decomposition products having an N-O site improve the electron blocking property of the negative electrode film and suppress the increase in resistance associated with the thickening of the film. At the same time, the other decomposition products having an R-O site destroy the negative electrode film, thicken the film during storage, and increase the resistance. On the other hand, the specific anion-containing compound brings about an improvement effect such as suppressing the increase in the resistance of the negative electrode by forming a Li-conductive film having a P-O bond or an S-O bond through adsorption and reductive decomposition reactions on the negative electrode. In contrast, when the compound represented by formula (1) and the specific anion-containing compound are present simultaneously in the vicinity of the negative electrode, the decomposition products having an R-O site generated by the reductive decomposition of the compound represented by formula (1) react with the specific anion-containing compound, thereby suppressing the destruction of the negative electrode film described above. Furthermore, the reaction product by the above reaction is alkyl-esterified, resulting in weakened coordination to Li, and it is considered that the negative electrode resistance after storage is suitably suppressed at a high level because a film having higher Li conductivity is formed.

[0027] [1-1. Compound Represented by Formula (1)] The non-aqueous electrolyte according to this embodiment contains a compound represented by the following formula (1). In formula (1), R is a hydrocarbon group having 5 to 10 carbon atoms. The compound represented by formula (1) may be used alone or in combination of two or more.

[0028] [Chemical Formula]

[0029] In formula (1), R has 5 to 10 carbon atoms, preferably 5 to 9 carbon atoms, more preferably 5 to 8 carbon atoms, still more preferably 6 to 7 carbon atoms, and even more preferably 6 carbon atoms. Here, from the viewpoint of the structural stability of the compound represented by formula (1) in the electrolytic solution, the number of carbon atoms is 5 or more, preferably 6 or more, and is 10 or less, preferably 9 or less, more preferably 8 or less, still more preferably 7 or less, and even more preferably 6 or less.

[0030] R in formula (1) is a hydrocarbon group. This hydrocarbon group may be linear, branched, or cyclic, but from the viewpoint of compound stability, a linear or branched form is preferred, and a linear form is more preferred.

[0031] Also, the hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group, but from the viewpoint of compound stability, a saturated hydrocarbon group is preferred. Examples of the saturated hydrocarbon group include an alkyl group, a cycloalkyl group, etc. Among them, from the viewpoint of compound stability, an alkyl group is more preferred. Examples of the unsaturated hydrocarbon group include an alkenyl group, an alkynyl group, an aryl group, etc. Among them, from the viewpoint of compound stability, an aryl group is preferred. Examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, etc., and from the viewpoint of compound stability, a phenyl group is preferred.

[0032] The hydrocarbon group may have some hydrogen atoms substituted by other functional groups or atoms as long as the effects of the present invention are not impaired.

[0033] Examples of the compound represented by formula (1) include the following compounds. Pentyl nitrite, 1-Methylbutyl nitrite, 2-Methylbutyl nitrite, 3-Methylbutyl nitrite, 1,1-Dimethylpropyl nitrite, 1,2-Dimethylpropyl nitrite, 2,2-Dimethylpropyl nitrite, 1-Ethylpropyl nitrite, Hexyl nitrite, 1-Methylpentyl nitrite, 2-Methylpentyl nitrite, 3-Methylpentyl nitrite, 4-Methylpentyl nitrite, 1,1-Dimethylbutyl nitrite, 1,2-Dimethylbutyl nitrite, 1,3-Dimethylbutyl nitrite, 2,2-Dimethylbutyl nitrite, 2,3-Dimethylbutyl nitrite, 3,3-Dimethylbutyl nitrite, 1-Ethylbutyl nitrite, 2-Ethylbutyl nitrite, Heptyl nitrite, 1-Methylhexyl nitrite, 2-Methylhexyl nitrite, 3-Methylhexyl nitrite, 4-Methylhexyl nitrite, 5-Methylhexyl nitrite, 1,1-Dimethylpentyl nitrite, 1,2-Dimethylpentyl nitrite, 1,3-Dimethylpentyl nitrite, 1,4-Dimethylpentyl nitrite, 2,2-Dimethylpentyl nitrite, 2,3-Dimethylpentyl nitrite, 2,4-Dimethylpentyl nitrite, 3,3-Dimethylpentyl nitrite, 3,4-Dimethylpentyl nitrite, 4,4-Dimethylpentyl nitrite, 1-Ethylpentyl nitrite, 2-Ethylpentyl nitrite, 3-Ethylpentyl nitrite, 4-Ethylpentyl nitrite, Octyl nitrite, 1-Methylheptyl nitrite, 2-Methylheptyl nitrite, 3-Methylheptyl nitrite, 4-Methylheptyl nitrite, 5-Methylheptyl nitrite, 6-Methylheptyl nitrite, 1,1-Dimethylhexyl nitrite, 1,2-Dimethylhexyl nitrite, 1,3-Dimethylhexyl nitrite, 1,4-Dimethylhexyl nitrite, 1,5-Dimethylhexyl nitrite, 2,2-Dimethylhexyl nitrite, 2,3-Dimethylhexyl nitrite, 2,4-Dimethylhexyl nitrite, 2,5-Dimethylhexyl nitrite, 3,3-Dimethylhexyl nitrite, 3,4-Dimethylhexyl nitrite, 3,5-Dimethylhexyl nitrite, 4,4-Dimethylhexyl nitrite, 4,5-Dimethylhexyl nitrite, 5,5-dimethylhexyl, 1-ethylhexyl nitrite, 2-ethylhexyl nitrite, 3-ethylhexyl nitrite, 4-ethylhexyl nitrite, nonyl nitrite, 1-methyloctyl nitrite, 2-methyloctyl nitrite, 3-methyloctyl nitrite, 4-methyloctyl nitrite, 5-methyloctyl nitrite, 6-methyloctyl nitrite, 7-methyloctyl nitrite, 1,1-dimethylheptyl nitrite, 1,2-dimethylheptyl nitrite, 1,3-dimethylheptyl nitrite, 1,4-dimethylheptyl nitrite, 1,5-dimethylheptyl nitrite, 1,6-dimethylheptyl nitrite, 2,2-dimethylheptyl nitrite, 2,3-dimethylheptyl nitrite, 2,4-dimethylheptyl nitrite, 2,5-dimethylheptyl nitrite, 2,6-dimethylheptyl nitrite, 3,3-dimethylheptyl nitrite, 3,4-dimethylheptyl nitrite, 3,5-dimethylheptyl nitrite, 3,6-dimethylheptyl nitrite, 4,4-dimethylheptyl nitrite, 4,5-dimethylheptyl nitrite, 4,6-dimethylheptyl nitrite, 5,5-dimethylheptyl nitrite, 5,6-dimethylheptyl nitrite, 6,6-dimethylheptyl nitrite, decyl nitrite, 1-methylnonyl nitrite, 2-methylnonyl nitrite, 3-methylnonyl nitrite, 4-methylnonyl nitrite, 5-methylnonyl nitrite, 6-methylnonyl nitrite, 7-methylnonyl nitrite, 8-methylnonyl nitrite, 1,1-dimethyloctyl nitrite, 1,2-dimethyloctyl nitrite, 1,3-dimethyloctyl nitrite, 1,4-dimethyloctyl nitrite, 1,5-dimethyloctyl nitrite, 1,6-dimethyloctyl nitrite, 1,7-dimethyloctyl nitrite, 2,2-dimethyloctyl nitrite, 2,3-dimethyloctyl nitrite, 2,4-dimethyloctyl nitrite, 2,5-dimethyloctyl nitrite, 2,6-dimethyloctyl nitrite, 2,7-dimethyloctyl nitrite, 3,3-dimethyloctyl nitrite, 3,4-dimethyloctyl nitrite, 3,5-dimethyloctyl nitrite, 3,6-dimethyloctyl nitrite, 3,7-dimethyloctyl nitrite, 4,4-dimethyloctyl nitrite, 4,5-dimethyloctyl nitrite, 4,6-dimethyloctyl nitrite, 4,7-dimethyloctyl nitrite, 5,5-dimethyloctyl nitrite, 5,6-dimethyloctyl nitrite, 5,7-dimethyloctyl, 6,6-dimethyloctyl nitrite, 6,7-dimethyloctyl nitrite, 7,7-dimethyloctyl nitrite, 1-pentenyl nitrite, 2-pentenyl nitrite, 3-pentenyl nitrite, 3-pentenyl nitrite, 4-pentenyl nitrite, 1-hexynyl nitrite, 2-hexynyl nitrite, 3-hexynyl nitrite, 4-hexynyl nitrite, 5-hexynyl nitrite, 1-heptynyl nitrite, 2-heptynyl nitrite, 3-heptynyl nitrite, 4-heptynyl nitrite, 5-heptynyl nitrite, 6-heptynyl nitrite, 1-octynyl nitrite, 2-octynyl nitrite, 3-octynyl nitrite, 4-octynyl nitrite, 5-octynyl nitrite, 6-octynyl nitrite, 7-octynyl nitrite, 1-nonyl nitrite, 2-nonyl nitrite, 3-nonyl nitrite, 4-nonyl nitrite, 5-nonyl nitrite, 6-nonyl nitrite, 7-nonyl nitrite, 8-nonyl nitrite, 1-decyl nitrite, 2-decyl nitrite, 3-decyl nitrite, 4-decyl nitrite, 5-decyl nitrite, 6-decyl nitrite, 7-decyl nitrite, 8-decyl nitrite, 9-decyl nitrite, cyclopentyl nitrite, cyclohexyl nitrite, cycloheptyl nitrite, cyclooctyl nitrite, cyclononyl nitrite, cyclodecyl nitrite, phenyl nitrite, tolyl nitrite, 2,3-xylyl nitrite, 2,4-xylyl nitrite, 2,5-xylyl nitrite, 2,6-xylyl nitrite, 3,4-xylyl nitrite, 3,5-xylyl nitrite, 3,6-xylyl nitrite, 4,5-xylyl nitrite, 4,6-xylyl nitrite.,

[0034] Among these, the following compounds are preferred in view of solubility in the electrolytic solution and ease of production. Pentyl nitrite, 1-Methylbutyl nitrite, 2-Methylbutyl nitrite, 3-Methylbutyl nitrite, 1,1-Dimethylpropyl nitrite, 1,2-Dimethylpropyl nitrite, 2,2-Dimethylpropyl nitrite, 1-Ethylpropyl nitrite, Hexyl nitrite, 1-Methylpentyl nitrite, 2-Methylpentyl nitrite, 3-Methylpentyl nitrite, 4-Methylpentyl nitrite, 1,1-Dimethylbutyl nitrite, 1,2-Dimethylbutyl nitrite, 1,3-Dimethylbutyl nitrite, 2,2-Dimethylbutyl nitrite, 2,3-Dimethylbutyl nitrite, 3,3-Dimethylbutyl nitrite, 1-Ethylbutyl nitrite, 2-Ethylbutyl nitrite, Heptyl nitrite, 1-Methylhexyl nitrite, 2-Methylhexyl nitrite, 3-Methylhexyl nitrite, 4-Methylhexyl nitrite, 5-Methylhexyl nitrite, 1,1-Dimethylpentyl nitrite, 1,2-Dimethylpentyl nitrite, 1,3-Dimethylpentyl nitrite, 1,4-Dimethylpentyl nitrite, 2,2-Dimethylpentyl nitrite, 2,3-Dimethylpentyl nitrite, 2,4-Dimethylpentyl nitrite, 3,3-Dimethylpentyl nitrite, 3,4-Dimethylpentyl nitrite, 4,4-Dimethylpentyl nitrite, 1-Ethylpentyl nitrite, 2-Ethylpentyl nitrite, 3-Ethylpentyl nitrite, 4-Ethylpentyl nitrite, Octyl nitrite, 1-Methylheptyl nitrite, 2-Methylheptyl nitrite, 3-Methylheptyl nitrite, 4-Methylheptyl nitrite, 5-Methylheptyl nitrite, 6-Methylheptyl nitrite, 1,1-Dimethylhexyl nitrite, 1,2-Dimethylhexyl nitrite, 1,3-Dimethylhexyl nitrite, 1,4-Dimethylhexyl nitrite, 1,5-Dimethylhexyl nitrite, 2,2-Dimethylhexyl nitrite, 2,3-Dimethylhexyl nitrite, 2,4-Dimethylhexyl nitrite, 2,5-Dimethylhexyl nitrite, 3,3-Dimethylhexyl nitrite, 3,4-Dimethylhexyl nitrite, 3,5-Dimethylhexyl nitrite, 4,4-Dimethylhexyl nitrite, 4,5-Dimethylhexyl nitrite, 5,5-Dimethylhexyl, 1-Ethylhexyl nitrite, 2-Ethylhexyl nitrite, 3-Ethylhexyl nitrite, 4-Ethylhexyl nitrite, Nonyl nitrite, 1-Methyloctyl nitrite, 2-Methyloctyl nitrite, 3-Methyloctyl nitrite, 4-Methyloctyl nitrite, 5-Methyloctyl nitrite, 6-Methyloctyl nitrite, 7-Methyloctyl nitrite, 1,1-Dimethylheptyl nitrite, 1,2-Dimethylheptyl nitrite, 1,3-Dimethylheptyl nitrite, 1,4-Dimethylheptyl nitrite, 1,5-Dimethylheptyl nitrite, 1,6-Dimethylheptyl nitrite, 2,2-Dimethylheptyl nitrite, 2,3-Dimethylheptyl nitrite, 2,4-Dimethylheptyl nitrite, 2,5-Dimethylheptyl nitrite, 2,6-Dimethylheptyl nitrite, 3,3-Dimethylheptyl nitrite, 3,4-Dimethylheptyl nitrite, 3,5-Dimethylheptyl nitrite, 3,6-Dimethylheptyl nitrite, 4,4-Dimethylheptyl nitrite, 4,5-Dimethylheptyl nitrite, 4,6-Dimethylheptyl nitrite, 5,5-Dimethylheptyl nitrite, 5,6-Dimethylheptyl nitrite, 6,6-Dimethylheptyl nitrite, Decyl nitrite, 1-Methylnonyl nitrite, 2-Methylnonyl nitrite, 3-Methylnonyl nitrite, 4-Methylnonyl nitrite, 5-Methylnonyl nitrite, 6-Methylnonyl nitrite, 7-Methylnonyl nitrite, 8-Methylnonyl nitrite, 1,1-Dimethyloctyl nitrite, 1,2-Dimethyloctyl nitrite, 1,3-Dimethyloctyl nitrite, 1,4-Dimethyloctyl nitrite, 1,5-Dimethyloctyl nitrite, 1,6-Dimethyloctyl nitrite, 1,7-Dimethyloctyl nitrite, 2,2-Dimethyloctyl nitrite, 2,3-Dimethyloctyl nitrite, 2,4-Dimethyloctyl nitrite, 2,5-Dimethyloctyl nitrite, 2,6-Dimethyloctyl nitrite, 2,7-Dimethyloctyl nitrite, 3,3-Dimethyloctyl nitrite, 3,4-Dimethyloctyl nitrite, 3,5-Dimethyloctyl nitrite, 3,6-Dimethyloctyl nitrite, 3,7-Dimethyloctyl nitrite, 4,4-Dimethyloctyl nitrite, 4,5-Dimethyloctyl nitrite, 4,6-Dimethyloctyl nitrite, 4,7-Dimethyloctyl nitrite, 5,5-Dimethyloctyl nitrite, 5,6-Dimethyloctyl nitrite, 5,7-dimethyloctyl, 6,6-dimethyloctyl nitrite, 6,7-dimethyloctyl nitrite, 7,7-dimethyloctyl nitrite.,

[0035] Among these, when the non-aqueous electrolyte according to the present embodiment is used in an energy device, pentyl nitrite, hexyl nitrite, isopentyl nitrite, and octyl nitrite are more preferable because of the low side reactions in the energy device.

[0036] Among these, pentyl nitrite and hexyl nitrite are most preferable because of the low side reactions in the energy device.

[0037] The content of the compound represented by the formula (1) in the total amount of the non-aqueous electrolyte (100% by mass) is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass, still more preferably 0.05 to 3% by mass, even more preferably 0.05 to 1% by mass, particularly preferably 0.1 to 1% by mass, and most preferably 0.2 to 0.5% by mass. Here, from the viewpoints of the capacity retention rate after the durability test and the ease of controlling the resistance, the above content is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, particularly preferably 0.2% by mass or more, and preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, even more preferably 1% by mass or less, and most preferably 0.5% by mass or less. When two or more kinds of the compounds represented by the formula (1) are contained, it is preferable that the total content satisfies the above range.

[0038] [1-2. Electrolyte] The electrolyte contained in the non-aqueous electrolyte according to the present embodiment is preferably an alkali metal salt such as lithium, sodium, or potassium. When the non-aqueous electrolyte according to the present embodiment is used in a lithium-ion battery, the counter cation in the above electrolyte is preferably a lithium cation. When the non-aqueous electrolyte according to this embodiment is used in a sodium ion battery, the counter cation in the above electrolyte is preferably a sodium ion. Further, when the non-aqueous electrolyte according to this embodiment is used in a potassium ion battery, the counter cation in the above electrolyte is preferably a potassium ion.

[0039] The electrolyte in this embodiment is classified into a "main salt" that mainly bears ion conduction and usually has a content in the non-aqueous electrolyte greater than 5% by mass, and an "auxiliary agent" with a content of 5% by mass or less. The electrolyte in this embodiment preferably contains an auxiliary agent in addition to the main salt. Also, the electrolyte in this embodiment preferably contains a specific anion-containing compound, and more preferably contains the specific anion-containing compound as an auxiliary agent. Therefore, the content of the specific anion-containing compound in the non-aqueous electrolyte is more preferably 5% by mass or less.

[0040] [1-2-1. Main salt] The electrolyte in the non-aqueous electrolyte according to this embodiment preferably contains, as the main salt, a compound other than the compound shown in [1-2-2. Specific anion-containing compound] described later. Other compounds serving as the electrolyte vary depending on the type of secondary battery to which the non-aqueous electrolyte is applied. For example, lithium salts are preferably mentioned, and sodium salts and potassium salts are also preferably mentioned.

[0041] There is no particular limitation on the lithium salt. For example, lithium fluoroborate salts, lithium fluorophosphate salts, lithium tungstate salts, lithium carboxylate salts, lithium sulfonate salts, lithium imide salts, lithium methide salts, lithium oxalate salts, and fluorine-containing organic lithium salts can be mentioned.

[0042] Among these, from the viewpoint of improving low-temperature output characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, cycle characteristics, etc., LiBF as a lithium fluoroborate salt 4 ; LiPF as a lithium fluorophosphate salt 6, Li 2 PO 3 F, LiPO 2 F 2 ; As a lithium sulfonate salt, LiFSO 3 , CH 3 SO 3 Li; As a lithium imide salt, LiN(FSO 2 ) 2 , LiN(FSO 2 )(CF 3 SO 2 ), LiN(CF 3 SO 2 ) 2 , LiN(C 2 F 5 SO 2 ) 2 , Lithium cyclic 1,2 - perfluoroethanedisulfonyl imide, lithium cyclic 1,3 - perfluoropropanedisulfonyl imide; As a lithium methide salt, LiC(FSO 2 ) 3 , LiC(CF 3 SO 2 ) 3 , LiC(C 2 F 5 SO 2 ) 3 ; As a lithium oxalate salt, lithium difluorooxalate borate, lithium bis(oxalate) borate, lithium tetrafluorooxalate phosphate, lithium difluorobis(oxalate) phosphate, lithium tris(oxalate) phosphate, etc. are preferable, LiPF 6 , LiN(FSO 2 ) 2 , Lithium bis(oxalate) borate and LiFSO 3 selected from one or more of them are more preferable, and LiPF 6 is particularly preferable.

[0043] Other compounds serving as the above electrolyte can be used alone or in combination of two or more in any ratio. There is no particular limitation on the combination of two or more other compounds serving as the electrolyte, and LiPF 6 and LiN(FSO 2 )2 combinations of LiPF 6 and LiBF 4 combinations of LiPF 6 and LiN(CF 3 SO 2 ) 2 combinations of LiBF 4 and LiN(FSO 2 ) 2 combinations of LiBF 4 , LiPF 6 and LiN(FSO 2 ) 2 Combinations such as these can be mentioned. Among these, combinations of LiPF 6 and LiN(FSO 2 ) 2 combinations of LiPF 6 and LiBF 4 combinations, and LiBF 4 , LiPF 6 and LiN(FSO 2 ) 2 combinations are preferred.

[0044] The sodium salts are not particularly limited, and examples include sodium fluoroborate salts, sodium fluorophosphate salts, sodium tungstate salts, sodium carboxylate salts, sodium sulfonate salts, sodium imide salts, sodium methide salts, sodium oxalate salts, and fluorine-containing organic sodium salts.

[0045] Among these, from the viewpoint of improving low-temperature output characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, cycle characteristics, etc., as sodium fluoroborate salts, NaBF 4 ; as sodium fluorophosphate salts, NaPF 6 , Na 2 PO 3 F, NaPO 2 F 2 ; as sodium sulfonate salts, NaFSO 3 , CH 3 SO 3 Na; as sodium imide salts, NaN(FSO2 ) 2 , NaN(FSO 2 )(CF 3 SO 2 ) , NaN(CF 3 SO 2 ) 2 , NaN(C 2 F 5 SO 2 ) 2 , sodium cyclic 1,2 - perfluoroethanedisulfonylimide, sodium cyclic 1,3 - perfluoropropanedisulfonylimide; as the sodium methide salt, NaC(FSO 2 ) 3 , NaC(CF 3 SO 2 ) 3 , NaC(C 2 F 5 SO 2 ) 3 ; as the sodium oxalate salt, sodium difluorooxalate borate, sodium bis(oxalate) borate, sodium tetrafluorooxalate phosphate, sodium difluorobis(oxalate) phosphate, sodium tris(oxalate) phosphate, etc. are preferable, NaPF 6 , NaN(FSO 2 ) 2 , sodium bis(oxalate) borate and NaFSO 3 selected from are more preferable, and NaPF 6 is particularly preferable.

[0046] Other compounds serving as the above electrolyte can be used alone or in combination of two or more in any ratio. There is no particular limitation on the combination of two or more other compounds serving as the electrolyte. Combinations such as NaPF 6 and NaN(FSO 2 ) 2 , the combination of NaPF 6 and NaBF 4 , the combination of NaPF 6 and NaN(CF 3 SO 2 ) 2combination of, NaBF 4 and NaN(FSO 2 ) 2 combination of, NaBF 4 , NaPF 6 and NaN(FSO 2 ) 2 combinations such as etc. can be mentioned. Among these, NaPF 6 and NaN(FSO 2 ) 2 combination of, NaPF 6 and NaBF 4 combination of, and NaBF 4 , NaPF 6 and NaN(FSO 2 ) 2 combination of is preferable.

[0047] Examples of the potassium salt include those obtained by substituting Li and Na in the above lithium salt and sodium salt with potassium (K) respectively.

[0048] The total content of the electrolyte in this embodiment is not particularly limited, but from the viewpoint of making the electric conductivity appropriate for battery operation and exhibiting sufficient output characteristics, it is usually 8% by mass or more, preferably 8.5% by mass or more, more preferably 9% by mass or more, and usually 18% by mass or less, preferably 17% by mass or less, more preferably 16% by mass or less, with respect to the total amount of the non-aqueous electrolyte. And the content of the electrolyte is usually 8% by mass or more and 18% by mass or less, preferably 8.5% by mass or more and 17% by mass or less, more preferably 9% by mass or more and 16% by mass or less, with respect to the total amount of the non-aqueous electrolyte. However, the content of the compound shown in [1-2-2. Specific anion-containing compound] described later is also included in the content of the above electrolyte. Also, when a compound corresponding to [1-4. Auxiliary agent] described later is included in the non-aqueous electrolyte, it necessarily contains an electrolyte other than the lithium salt corresponding to the auxiliary agent. The identification and measurement of the content of the electrolyte are performed by nuclear magnetic resonance (NMR) spectroscopy.

[0049] [1-2-2. Specific anion-containing compound] The electrolyte in the non-aqueous electrolyte according to this embodiment contains a specific anion-containing compound. In this specification, the specific anion-containing compound is at least one compound selected from the group consisting of an anion-containing compound having a P=O bond and a P-F bond, and an anion-containing compound having an S=O bond and an S-X bond (X: heteroatom).

[0050] The above specific anion-containing compound is usually an acid or a salt, and preferably a salt. As the counter cation in the specific anion-containing compound, an alkali metal cation such as lithium, sodium, or potassium is preferable, and a lithium cation is more preferable. When the non-aqueous electrolyte according to this embodiment is used in a lithium-ion battery, the counter cation is preferably a lithium cation. When it is used in a sodium-ion battery, the counter cation is preferably a sodium ion. When it is used in a potassium-ion battery, the counter cation is preferably a potassium ion.

[0051] There is no particular limitation on the method of adding the above specific anion-containing compound to the non-aqueous electrolyte, but examples include a method of adding a salt of the specific anion-containing compound. A method of adding one or more selected from the group consisting of lithium salts, sodium salts, and potassium salts of the specific anion-containing compound is preferable, and a method of adding a lithium salt of the specific anion-containing compound is more preferable. Also, a method of adding a raw material of the specific anion-containing compound to the electrolyte and generating the specific anion-containing compound in the electrolyte is also preferable.

[0052] At least one specific anion-containing compound selected from the group consisting of an anion-containing compound having a P=O bond and a P-F bond, and an anion-containing compound having an S=O bond and an S-X bond (X: heteroatom) can be used alone or in combination of two or more in any ratio.

[0053] Among these, from the viewpoint of suppressing the internal resistance increase rate after high-temperature storage, an anion-containing compound having a P-F bond and a P=O bond is particularly preferable.

[0054] [1-2-3. Anion-containing compound having a P-F bond and a P=O bond] As the anion-containing compound having a P-F bond and a P=O bond, which is one aspect of the specific anion-containing compound in the present embodiment, for example, 3 F 2- such as monofluorophosphate anions, 2 F 2 - and compounds containing difluorophosphate anions such as can be mentioned. Among these, from the viewpoint of the balance between the output characteristics of the battery and the protection of the electrode interface, compounds containing difluorophosphate anions are preferable.

[0055] There is no particular limitation on the method of adding the anion-containing compound having a P-F bond and a P=O bond to the electrolytic solution, but examples include the method of adding a salt of the anion-containing compound having a P-F bond and a P=O bond. A method of adding one or more selected from lithium monofluorophosphate, lithium difluorophosphate, sodium monofluorophosphate, sodium difluorophosphate, potassium monofluorophosphate, and potassium difluorophosphate is preferable, and a method of adding at least one of lithium monofluorophosphate and lithium difluorophosphate is more preferable. Also, a method of adding a raw material of the anion-containing compound having a P-F bond and a P=O bond to the electrolytic solution and generating the anion-containing compound having a P-F bond and a P=O bond in the electrolytic solution is also preferable.

[0056] [1-2-4. Anion-containing compound having an S=O bond and an S-X bond] Among the anion-containing compounds having an S=O bond and an S-X bond, which is one aspect of the specific anion-containing compound in the present embodiment, X in the S-X bond represents a heteroatom. Specific examples of the heteroatom include an oxygen atom, a nitrogen atom, a fluorine atom, and the like.

[0057] Specific examples of the anion-containing compound having an S═O bond and an S—X bond include, for example, FSO 3 - and other fluorosulfonic acid anions; (FSO 2 ) 2 N - , (FSO 2 )(CF 3 SO 2 )N - and other fluorosulfonylimide anions; (FSO 2 ) 3 C - and other compounds containing fluorosulfonylmethide anions; CH 3 SO 4 - , C 2 H 5 SO 4 - and other compounds containing alkyl sulfate anions, etc. can be mentioned. Among these, from the viewpoint of the balance between the output characteristics of the battery and the protection of the electrode interface, compounds containing fluorosulfonic acid anions, fluorosulfonylimide anions, and alkyl sulfate anions are preferred, compounds containing fluorosulfonic acid anions and fluorosulfonylimide anions are more preferred, and compounds containing fluorosulfonic acid anions are even more preferred.

[0058] There is no particular limitation on the method of adding an anion-containing compound having an S=O bond and an S-X bond to the electrolytic solution. Examples include methods of adding salts of anion-containing compounds having an S=O bond and an S-X bond. Preferred are methods of adding one or more selected from lithium fluorosulfonate, lithium fluorosulfonyl imide, sodium fluorosulfonate, sodium fluorosulfonyl imide, potassium fluorosulfonate, potassium fluorosulfonyl imide, lithium methyl sulfate, lithium ethyl sulfate, sodium methyl sulfate, sodium ethyl sulfate, potassium methyl sulfate, and potassium ethyl sulfate. More preferred are methods of adding one or more selected from lithium fluorosulfonate, lithium fluorosulfonyl imide, lithium methyl sulfate, and lithium ethyl sulfate. Also preferred is a method of adding a raw material of an anion-containing compound having an S=O bond and an S-X bond to the electrolytic solution and generating an anion-containing compound having an S=O bond and an S-X bond in the electrolytic solution.

[0059] [Content of Specific Anion-Containing Compound] From the viewpoint of significantly improving battery characteristics, particularly the DC resistance (DCR) retention rate after high-temperature storage, the content of the specific anion-containing compound in the non-aqueous electrolytic solution according to this embodiment is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.1% by mass or more, and is preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less. And the content of the above specific anion-containing compound is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.01% by mass or more and 4% by mass or less, still more preferably 0.1% by mass or more and 3% by mass or less. Note that the above content means the total content when two or more specific anion-containing compounds are included.

[0060] By containing a specific anion-containing compound in the non-aqueous electrolyte according to this embodiment, battery characteristics, particularly the DCR retention rate after high-temperature storage, can be improved. The reason for this is not clear, but the specific anion-containing compound can minimize the side reactions of the components of the non-aqueous electrolyte on the electrode surface, and such an effect is considered to be more preferably exhibited within the range of the content of the specific anion-containing compound. The identification and measurement of the content of the specific anion-containing compound are carried out by nuclear magnetic resonance (NMR) spectroscopy, ion chromatography (IC), etc.

[0061] 〔Mass ratio of the specific anion-containing compound to the compound represented by formula (I)〕 The mass ratio of the content of the specific anion-containing compound to the compound represented by formula (I), that is, when the content of the compound represented by formula (I) in the total amount of the non-aqueous electrolyte is α mass%, and the content of the specific anion-containing compound in the total amount of the non-aqueous electrolyte is β mass%, the ratio of the content represented by β / α is not particularly limited, but from the viewpoint of improving the DCR retention rate during high-temperature charge storage, it is usually 0.01 or more, preferably 0.05 or more, more preferably 0.1 or more, further preferably 0.5 or more, even more preferably 0.8 or more, still more preferably 1.2 or more, yet more preferably 1.5 or more, even more preferably 1.8 or more, particularly preferably 1.9 or more, and it is usually 100 or less, preferably 60 or less, more preferably 45 or less, further preferably 35 or less, still more preferably 30 or less, even more preferably 25 or less, yet more preferably 22 or less, even more preferably 18 or less, still more preferably 15 or less, yet more preferably 12 or less, particularly preferably 11 or less. And the above mass ratio is usually 0.01 or more and 100 or less, preferably 0.05 or more and 60 or less, more preferably 0.1 or more and 45 or less, still more preferably 0.5 or more and 35 or less, even more preferably 0.8 or more and 30 or less, yet more preferably 1.2 or more and 25 or less, still more preferably 1.5 or more and 22 or less, even more preferably 1.8 or more and 18 or less, yet even more preferably 1.8 or more and 15 or less, still even more preferably 1.9 or more and 12 or less, particularly preferably 1.9 or more and 11 or less. In addition, the contents of the compound represented by the above formula (I) and the specific anion-containing compound respectively mean the total content when two or more of them are contained.

[0062] If the above mass ratio is within the above range, battery characteristics, particularly the DCR retention rate after high-temperature storage, can be significantly improved, and the internal resistance increase rate after high-temperature storage can be significantly suppressed. Although the reason for this is not clear, it is considered that by containing the compound represented by the formula (I) and the specific anion-containing compound within the above mass ratio range, the side reaction of the components of the non-aqueous electrolyte on the electrode surface can be minimized.

[0063] [Mass ratio of the specific anion-containing compound to the main salt] The electrolyte in the non-aqueous electrolyte according to this embodiment contains the above specific anion-containing compound. However, the mass ratio of the content of the specific anion-containing compound to the content of the main salt constituting the electrolyte, that is, the mass ratio represented by specific anion-containing compound [g] / main salt [g], is usually 0.00005 or more, preferably 0.0005 or more, more preferably 0.001 or more, still more preferably 0.005 or more, even more preferably 0.01 or more, and particularly preferably 0.015 or more. Also, it is usually 0.5 or less, preferably 0.45 or less, more preferably 0.4 or less, and still more preferably 0.35 or less. And the above mass ratio is usually 0.00005 or more and 0.5 or less, preferably 0.0005 or more and 0.5 or less, more preferably 0.001 or more and 0.45 or less, still more preferably 0.005 or more and 0.4 or less, even more preferably 0.01 or more and 0.35 or less, and particularly preferably 0.015 or more and 0.35 or less. Note that the content of the above specific anion-containing compound means the total content when two or more specific anion-containing compounds are included.

[0064] If the above mass ratio is within the above range, battery characteristics, particularly the DCR maintenance rate after high-temperature storage, can be significantly improved, and the internal resistance increase rate after high-temperature storage can be significantly suppressed. The reason for this is not clear, but it is considered that within the above mass ratio range, by containing a specific anion-containing compound and a main salt, side reactions of the electrolyte in the battery system can be minimized.

[0065] [1-2-5. Other Anion-Containing Compounds] The electrolyte in this embodiment may further contain other anion-containing compounds in addition to the above specific anion-containing compound. The other anion-containing compound is not particularly limited, and examples thereof include oxalate complex anion-containing compounds.

[0066] [1-2-6. Oxalate Complex Anion-Containing Compounds] The oxalate complex anion-containing compound in this embodiment is not particularly limited as long as it is a compound containing an anion having an oxalate complex in the molecule. The oxalate complex anion-containing compound is a compound containing an anion of an acid in which oxalic acid coordinates or binds to a central atom to form a complex. For example, a compound containing a boron oxalate complex anion in which oxalic acid coordinates or binds to a boron atom, or a phosphorus oxalate complex anion in which oxalic acid coordinates or binds to a phosphorus atom can be mentioned.

[0067] Examples of the boron oxalate complex anion include bis(oxalato)borate anion, difluorooxalato borate anion, and the like. Examples of the phosphorus oxalate complex anion include tetrafluorooxalato phosphate anion, difluorobis(oxalato)phosphate anion, tris(oxalato)phosphate anion, and the like. Among these, from the viewpoint of forming a stable interfacial protective film (composite film) on the surface of the electrode, a compound containing a boron oxalate complex anion is preferable, and a compound containing bis(oxalato)borate anion is more preferable.

[0068] There is no particular limitation on the method of adding the oxalate complex anion-containing compound to the electrolytic solution, but examples include the method of adding a salt of the oxalate complex anion-containing compound. Preferred is a method of adding one or more selected from lithium bis(oxalato)borate, lithium difluorooxalato borate, lithium tetrafluorooxalato phosphate, lithium difluorobis(oxalato)phosphate, lithium tris(oxalato)phosphate, sodium bis(oxalato)borate, sodium difluorooxalato borate, sodium tetrafluorooxalato phosphate, sodium difluorobis(oxalato)phosphate, sodium tris(oxalato)phosphate, potassium bis(oxalato)borate, potassium difluorooxalato borate, potassium tetrafluorooxalato phosphate, potassium difluorobis(oxalato)phosphate, and potassium tris(oxalato)phosphate. More preferred is a method of adding one or more selected from lithium bis(oxalato)borate, lithium difluorooxalato borate, lithium tetrafluorooxalato phosphate, lithium difluorobis(oxalato)phosphate, and lithium tris(oxalato)phosphate. Also preferred is a method of adding a raw material of the oxalate complex anion-containing compound to the electrolytic solution and generating the oxalate complex anion-containing compound in the electrolytic solution.

[0069] [1-3. Non-aqueous solvent] The non-aqueous electrolytic solution according to this embodiment contains a non-aqueous solvent. The non-aqueous solvent is a component that dissolves the above-described electrolyte.

[0070] There is no particular limitation on the non-aqueous solvent, and known organic solvents can be used. Examples of the organic solvent include saturated cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; chain carboxylic acid esters such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; cyclic carboxylic acid esters such as γ-butyrolactone and γ-valerolactone; ether compounds such as dimethoxymethane, diethoxymethane, ethoxymethoxymethane, tetrahydrofuran, 1,3-dioxane, and 1,4-dioxane; and sulfone compounds such as 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, dimethyl sulfone, ethyl methyl sulfone, and monofluoromethyl methyl sulfone. Among these, saturated cyclic carbonates, chain carbonates, and chain or cyclic carboxylic acid esters are preferred, and saturated cyclic carbonates and chain carbonates are more preferred. These non-aqueous solvents can be used alone or in combination of two or more.

[0071] There is no particular limitation on the combination of two or more non-aqueous solvents. Examples include combinations of saturated cyclic carbonates and chain carboxylic acid esters, cyclic carboxylic acid esters and chain carbonates, and saturated cyclic carbonates, chain carbonates, and chain carboxylic acid esters. Among them, combinations of saturated cyclic carbonates and chain carbonates, and combinations of saturated cyclic carbonates, chain carbonates, and chain carboxylic acid esters are preferred.

[0072] [1-3-1. Saturated Cyclic Carbonate] Examples of the saturated cyclic carbonate, which is one aspect of the non-aqueous solvent in the present embodiment, generally include those having an alkylene group with 2 to 4 carbon atoms. From the viewpoint of improving battery characteristics due to the improvement of lithium ion dissociation degree, saturated cyclic carbonates with 2 to 3 carbon atoms are preferably used.

[0073] Examples of the saturated cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate and the like. Among them, ethylene carbonate and propylene carbonate are preferable, and ethylene carbonate which is less likely to be oxidized or reduced is more preferable. The saturated cyclic carbonate may be used alone or in combination of two or more in any combination and ratio.

[0074] The content of the saturated cyclic carbonate is not particularly limited and may be arbitrary as long as the effects of the present invention are not significantly impaired. However, it is usually 3 to 90% by volume, preferably 3 to 85% by volume, and more preferably 5 to 80% by volume with respect to the total amount of the non-aqueous solvent in the non-aqueous electrolyte. Here, the above content is usually 3% by volume or more, preferably 5% by volume or more, while usually 90% by volume or less, preferably 85% by volume or less, and more preferably 80% by volume or less. By setting the range within this range, it is possible to avoid a decrease in the electrical conductivity resulting from a decrease in the dielectric constant of the non-aqueous electrolyte, and it is easy to make the high-current discharge characteristics, the stability with respect to the negative electrode, and the cycle characteristics of the non-aqueous electrolyte secondary battery fall within a good range. The oxidation-reduction resistance of the non-aqueous electrolyte is improved, and the stability during high-temperature storage tends to be improved. Note that the volume % in the present embodiment means the volume at 25°C and 1 atm.

[0075] [1-3-2. Chain carbonate] As the chain carbonate which is one aspect of the non-aqueous solvent in the present embodiment, those having usually 3 to 7 carbon atoms are used, and chain carbonates having 3 to 5 carbon atoms are preferably used in order to adjust the viscosity of the electrolyte to an appropriate range.

[0076] Specific examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, and methyl-n-propyl carbonate. Particularly preferred are dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0077] In addition, chain carbonates having fluorine atoms (hereinafter may be abbreviated as "fluorinated chain carbonates") can also be preferably used. The number of fluorine atoms in the fluorinated chain carbonate is not particularly limited as long as it is 1 or more, but is usually 6 or less, preferably 4 or less. When the fluorinated chain carbonate has a plurality of fluorine atoms, they may be bonded to the same carbon or different carbons.

[0078] Examples of the fluorinated chain carbonate include fluorinated dimethyl carbonate derivatives such as fluoromethyl methyl carbonate, fluorinated ethyl methyl carbonate derivatives such as 2-fluoroethyl methyl carbonate, and fluorinated diethyl carbonate derivatives such as ethyl-(2-fluoroethyl) carbonate.

[0079] The chain carbonate may be used alone or in combination of two or more in any combination and ratio.

[0080] The content of the chain carbonate is not particularly limited, but is usually 15 to 90% by volume, preferably 20 to 85% by volume, and more preferably 25 to 80% by volume based on the total amount of the non-aqueous solvent in the non-aqueous electrolyte. Here, the above content is usually 15% by volume or more, preferably 20% by volume or more, more preferably 25% by volume or more, and is usually 90% by volume or less, preferably 85% by volume or less, more preferably 80% by volume or less. By setting the content of the chain carbonate within the above range, the viscosity of the non-aqueous electrolyte can be set within an appropriate range, the decrease in ionic conductivity can be suppressed, and thus the output characteristics of the non-aqueous electrolyte secondary battery can be easily set within a good range.

[0081] Furthermore, by combining ethylene carbonate with a specific content with respect to a specific chain carbonate, the battery performance can be significantly improved.

[0082] For example, when dimethyl carbonate and ethyl methyl carbonate are selected as specific chain carbonates, the content of ethylene carbonate is not particularly limited and can be arbitrary as long as the effects of the present invention are not significantly impaired. However, it is usually 15 to 45% by volume, preferably 20 to 40% by volume, based on the total amount of non-aqueous solvents in the non-aqueous electrolyte. Here, the above content is usually 15% by volume or more, preferably 20% by volume or more, and usually 45% by volume or less, preferably 40% by volume or less. Also, the content of dimethyl carbonate is usually 20 to 50% by volume, preferably 30 to 45% by volume, based on the total amount of non-aqueous solvents in the non-aqueous electrolyte. Here, the above content is usually 20% by volume or more, preferably 30% by volume or more, and usually 50% by volume or less, preferably 45% by volume or less. Further, the content of ethyl methyl carbonate is usually 20 to 50% by volume, preferably 30 to 45% by volume, based on the total amount of non-aqueous solvents in the non-aqueous electrolyte. Here, the above content is usually 20% by volume or more, preferably 30% by volume or more, and usually 50% by volume or less, preferably 45% by volume or less. By setting each content within the above range, excellent high-temperature stability and a tendency to suppress gas generation can be achieved.

[0083] [1-3-3. Chain carboxylic acid esters] Examples of the chain carboxylic acid ester, which is one aspect of the non-aqueous solvent in the present embodiment, include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, methyl valerate, methyl isobutyrate, ethyl isobutyrate, and methyl pivalate. Among them, methyl acetate, ethyl acetate, propyl acetate, and butyl acetate are preferable from the viewpoint of improving battery characteristics. Also, chain carboxylic acid esters in which a part of the hydrogen of each of the above chain carboxylic acid esters is substituted with fluorine can also be preferably used. Examples of such chain carboxylic acid esters substituted with fluorine include methyl trifluoroacetate, ethyl trifluoroacetate, and the like.

[0084] [1-3-4. Cyclic carboxylic acid esters] Examples of the cyclic carboxylic acid ester, which is one aspect of the non-aqueous solvent in this embodiment, include γ-butyrolactone and γ-valerolactone. Among these, γ-butyrolactone is more preferable. A cyclic carboxylic acid ester in which a part of the hydrogen of each of the above cyclic carboxylic acid esters is substituted with fluorine can also be suitably used.

[0085] [1-3-5. Ether Compounds] Examples of the ether compound, which is one aspect of the non-aqueous solvent in this embodiment, include chain ethers having 3 to 10 carbon atoms such as dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether, and cyclic ethers having 3 to 6 carbon atoms such as tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, and 1,4-dioxane are preferable.

[0086] Among them, as the chain ether having 3 to 10 carbon atoms, dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are preferable because they have a high solvation ability for lithium ions, improve ion dissociation, have low viscosity, and provide high ionic conductivity. Also, as the cyclic ether having 3 to 6 carbon atoms, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, etc. are preferable because they provide high ionic conductivity.

[0087] The content of the ether-based compound is not particularly limited and is arbitrary as long as the effects of the invention according to this embodiment are not significantly impaired. However, it is usually 1 to 30% by volume, preferably 2 to 25% by volume, and more preferably 3 to 20% by volume with respect to the total amount of the non-aqueous solvent. Here, the above content is usually 1% by volume or more, preferably 2% by volume or more, more preferably 3% by volume or more, and usually 30% by volume or less, preferably 25% by volume or less, more preferably 20% by volume or less. If the content of the ether-based compound is within the above range, it is easy to ensure the effect of improving the ionic conductivity derived from the improvement of the lithium ion dissociation degree of the ether and the decrease in viscosity. Further, when the negative electrode active material is a carbon-based material, since the phenomenon of co-insertion of the chain ether with lithium ions can be suppressed, the input / output characteristics and the charge / discharge rate characteristics can be made within an appropriate range.

[0088] [1-3-6. Sulfone-based compound] As the sulfone-based compound which is one aspect of the non-aqueous solvent in this embodiment, either cyclic sulfone or chain sulfone is not particularly limited. In the case of cyclic sulfone, the number of carbon atoms is usually 3 to 6, preferably 3 to 5. In the case of chain sulfone, the number of carbon atoms is usually 2 to 6, preferably 2 to 5. Further, the number of sulfonyl groups in one molecule of the sulfone-based compound is not particularly limited, but is usually 1 or 2.

[0089] Examples of the cyclic sulfone include trimethylene sulfones, tetramethylene sulfones, hexamethylene sulfones which are monosulfone compounds; trimethylene disulfones, tetramethylene disulfones, hexamethylene disulfones which are disulfone compounds, and the like. Among them, from the viewpoints of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, hexamethylene disulfones are more preferable, and tetramethylene sulfones (sulfolanes) are particularly preferable.

[0090] As the sulfolanes, sulfolane and / or sulfolane derivatives (hereinafter, may be abbreviated as "sulfolanes" including sulfolane) are preferable. As the sulfolane derivatives, those in which one or more of the hydrogen atoms bonded to the carbon atoms constituting the sulfolane ring are substituted with fluorine atoms or alkyl groups are preferable.

[0091] Among them, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,3-difluorosulfolane, 2-trifluoromethylsulfolane, 3-trifluoromethylsulfolane, etc. are preferable in terms of high ionic conductivity and high input / output.

[0092] Further, examples of the chain sulfones include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, pentafluoroethyl methyl sulfone, etc. Among them, dimethyl sulfone, ethyl methyl sulfone, and monofluoromethyl methyl sulfone are preferable in terms of improving the high-temperature storage stability of the electrolytic solution.

[0093] The content of the sulfone-based compound is not particularly limited and is arbitrary as long as the effects of the invention according to the present embodiment are not significantly impaired. However, it is usually 0.3 to 40% by volume, preferably 0.5 to 35% by volume, and more preferably 1 to 30% by volume with respect to the total amount of the non-aqueous solvent in the non-aqueous electrolytic solution. Here, the above content is usually 0.3% by volume or more, preferably 0.5% by volume or more, more preferably 1% by volume or more, and usually 40% by volume or less, preferably 35% by volume or less, more preferably 30% by volume or less. If the content of the sulfone-based compound is within the above range, an electrolytic solution excellent in high-temperature storage stability tends to be obtained.

[0094] [1-4. Auxiliary agent] The non-aqueous electrolyte according to this embodiment may contain various auxiliary agents as long as the effects of the present invention are not impaired. As the auxiliary agents, conventionally known ones can be arbitrarily used. The auxiliary agents can be used alone or in combination of two or more in any ratio.

[0095] Examples of the auxiliary agents include cyclic carbonates having a carbon-carbon unsaturated bond, fluorine-containing cyclic carbonates, compounds having an isocyanate group, compounds having an isocyanuric acid skeleton, sulfur-containing organic compounds, phosphorus-containing organic compounds, silicon-containing compounds, aromatic compounds, organic compounds having a cyano group, fluorine-free carboxylic acid esters, cyclic ether compounds, acid anhydrides, triple bond-containing compounds, phosphazene compounds, and the like. More specifically, for example, the compounds described in International Publication No. 2015 / 111676 can be mentioned.

[0096] Among these, at least one carbonate compound selected from the group consisting of cyclic carbonates having a carbon-carbon unsaturated bond and fluorine-containing cyclic carbonates (hereinafter, also referred to as "specific carbonate compound") is preferable.

[0097] The content of the auxiliary agent is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. However, it is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, particularly preferably less than 1% by mass, based on the total amount of the non-aqueous electrolyte. And the content of the auxiliary agent is usually 0.001% by mass or more and 10% by mass or less, preferably 0.01% by mass or more and 5% by mass or less, more preferably 0.1% by mass or more and 3% by mass or less, still more preferably 0.1% by mass or more and 1% by mass or less, particularly preferably 0.1% by mass or more and less than 1% by mass, based on the total amount of the non-aqueous electrolyte.

[0098] Here, the cyclic ether compound can be used as an auxiliary agent in the non-aqueous electrolyte, and also includes those that can be used as a non-aqueous solvent as shown in the column of [1-3. Non-aqueous solvent]. When using a cyclic ether compound as an auxiliary agent, it is used in an amount of 5% by mass or less, preferably less than 4% by mass, based on the total amount of the non-aqueous electrolyte.

[0099] In addition, a boric acid anion-containing compound, an oxalate complex anion-containing compound, a monofluorophosphate anion-containing compound, and a difluorophosphate anion-containing compound can be used as auxiliary agents in the non-aqueous electrolyte, and also include those that can be used as electrolytes as described in the column of [1-2. Electrolyte]. When using these compounds as auxiliary agents, it is preferably used in an amount of less than 3% by mass based on the total amount of the non-aqueous electrolyte.

[0100] [1-4-1. Specific carbonate compound] As described above, the non-aqueous electrolyte according to the present embodiment preferably contains at least one carbonate compound selected from the group consisting of a cyclic carbonate having a carbon-carbon unsaturated bond and a cyclic carbonate having a fluorine atom as an auxiliary agent. Among these, it is preferable to contain a cyclic carbonate having a carbon-carbon unsaturated bond, and more preferably to contain vinylene carbonate. These can be used alone or in combination of two or more in any ratio.

[0101] When using two or more specific carbonate compounds in combination, it is preferable to combine an unsaturated cyclic carbonate and a fluorinated cyclic carbonate, more preferably to combine vinylene carbonate and a fluorinated cyclic carbonate, and still more preferably to combine an unsaturated cyclic carbonate and monofluoroethylene carbonate, and most preferably to combine vinylene carbonate and monofluoroethylene carbonate.

[0102] 〔Content of specific carbonate compound〕 In the total amount of the non-aqueous electrolyte according to this embodiment, the content of the specific carbonate compound is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.5% by mass or more, and is usually 10% by mass or less, preferably 6% by mass or less, more preferably 5% by mass or less, still more preferably 4% by mass or less. And, the content of the specific carbonate compound in the total amount of the non-aqueous electrolyte is usually 0.001% by mass or more and 10% by mass or less, preferably 0.01% by mass or more and 6% by mass or less, more preferably 0.1% by mass or more and 5% by mass or less, still more preferably 0.5% by mass or more and 4% by mass or less. When two or more specific carbonate compounds are included, the above content means the total content thereof. If the content of the specific carbonate compound is within the above range, battery characteristics, particularly durability, can be improved. Although the reason for this is not clear, it is considered that by containing the specific carbonate compound at this ratio, an interfacial protective film is formed on the electrode, minimizing side reactions of the components of the non-aqueous electrolyte. The identification and content measurement of the specific carbonate compound are performed by nuclear magnetic resonance (NMR) spectroscopy.

[0103] 〔Mass ratio of the specific carbonate compound to the compound represented by formula (I)〕 In this embodiment, the mass ratio of the content of the specific carbonate compound in the total amount of the non-aqueous electrolyte to the content of the compound represented by formula (I) in the same total amount, that is, the mass ratio represented by specific carbonate compound [g] / compound represented by formula (I) [g] is usually 0.01 or more, preferably 0.05 or more, more preferably 0.3 or more, still more preferably 0.5 or more, and is usually 100 or less, preferably 10 or less, more preferably 5 or less, still more preferably 4 or less. And, the above mass ratio is usually 0.01 or more and 100 or less, preferably 0.05 or more and 10 or less, more preferably 0.3 or more and 5 or less, still more preferably 0.5 or more and 4 or less. When two or more compounds represented by formula (I) and specific carbonate compounds are included, the above content means the total content thereof, respectively. If the mass ratio is within the above range, battery characteristics, particularly durability, can be improved. Although the reason is not clear, it is considered that within the range of the above mass ratio, by containing a specific carbonate compound and the compound represented by the formula (I), an interfacial protective film is formed on the electrode, minimizing side reactions of the components of the non-aqueous electrolyte.

[0104] [Mass ratio of a specific carbonate compound to the main salt] In the non-aqueous electrolyte according to this embodiment, the mass ratio of the content of the specific carbonate compound in the total amount of the non-aqueous electrolyte to the total content of the main salts constituting the electrolyte in the total amount of the non-aqueous electrolyte, that is, the mass ratio represented by specific carbonate compound [g] / main salt [g] is usually 0.00005 or more, preferably 0.0005 or more, more preferably 0.001 or more, still more preferably 0.01 or more, even more preferably 0.02 or more, particularly preferably 0.025 or more, and is usually 0.5 or less, preferably 0.45 or less, more preferably 0.4 or less, still more preferably 0.35 or less. And the above mass ratio is usually 0.00005 or more and 0.5 or less, preferably 0.0005 or more and 0.5 or less, more preferably 0.001 or more and 0.45 or less, still more preferably 0.01 or more and 0.4 or less, even more preferably 0.02 or more and 0.35 or less, particularly preferably 0.025 or more and 0.35 or less. When two or more kinds of main salts and specific carbonate compounds are contained respectively, the above contents respectively mean their total contents. If the mass ratio is within the above range, battery characteristics, particularly durability, can be improved. Although the reason is not clear, it is considered that within the range of the above mass ratio, by containing a specific carbonate compound and the main salt, an interfacial protective film is formed on the electrode, minimizing side reactions of the electrolyte in the battery system.

[0105] [1-4-1-1. Cyclic carbonate having a carbon-carbon unsaturated bond] As a cyclic carbonate having a carbon-carbon unsaturated bond, which is one embodiment of a specific carbonate compound in the present embodiment (hereinafter also referred to as "unsaturated cyclic carbonate"), there is no particular limitation as long as it is a cyclic carbonate having a carbon-carbon double bond or a carbon-carbon triple bond. A cyclic carbonate having an aromatic ring is also to be included in the unsaturated cyclic carbonate.

[0106] Examples of the unsaturated cyclic carbonate include vinylene carbonates, ethylene carbonates substituted with a substituent having an aromatic ring, a carbon-carbon double bond or a carbon-carbon triple bond, phenyl carbonates, vinyl carbonates, allyl carbonates, catechol carbonates and the like. Among these, vinylene carbonates, ethylene carbonates substituted with a substituent having an aromatic ring, a carbon-carbon double bond or a carbon-carbon triple bond are preferable.

[0107] Examples of the vinylene carbonates include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, vinyl vinylene carbonate, 4,5-vinyl vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate and the like.

[0108] Examples of the ethylene carbonates substituted with a substituent having an aromatic ring, a carbon-carbon double bond or a carbon-carbon triple bond include vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, 4-allyl-5-vinyl ethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate, 4-vinyl-5-ethynyl ethylene carbonate, 4-allyl-5-ethynyl ethylene carbonate, phenyl ethylene carbonate, 4,5-diphenyl ethylene carbonate, 4-phenyl-5-vinyl ethylene carbonate, 4-allyl-5-phenyl ethylene carbonate, allyl ethylene carbonate, 4,5-diallyl ethylene carbonate, 4-methyl-5-allyl ethylene carbonate and the like. Among these, vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate are preferable because they form a more stable interfacial protective film (composite film) on the electrode. One or more selected from vinylene carbonate and vinyl ethylene carbonate are more preferable, and vinylene carbonate is even more preferable.

[0109] The unsaturated cyclic carbonates can be used alone or in combination of two or more in any ratio.

[0110] [1-4-1-2. Cyclic Carbonate Having a Fluorine Atom] The cyclic carbonate having a fluorine atom, which is one aspect of the specific carbonate compound in the present embodiment, is not particularly limited as long as it has a cyclic carbonate structure and contains a fluorine atom.

[0111] Examples of the cyclic carbonate having a fluorine atom include fluorides of cyclic carbonates having an alkylene group with 2 to 6 carbon atoms and derivatives thereof. More specifically, fluorides of ethylene carbonate (fluoroethylene carbonate) and derivatives thereof, and ethylene carbonates having a fluorine-containing group are included.

[0112] Examples of the fluorinated derivative of ethylene carbonate include fluorinated ethylene carbonates substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms). Among these, fluorinated ethylene carbonates having 1 to 8 fluorine atoms and their derivatives are preferable.

[0113] Examples of the fluorinated ethylene carbonate having 1 to 8 fluorine atoms, its derivatives, and the ethylene carbonate having a fluorine-containing group include monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4-(fluoromethyl)-ethylene carbonate, 4-(difluoromethyl)-ethylene carbonate, 4-(trifluoromethyl)-ethylene carbonate, 4-(fluoromethyl)-4-fluoroethylene carbonate, 4-(fluoromethyl)-5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, 4,4-difluoro-5,5-dimethylethylene carbonate, and the like. Among these, from the viewpoint of imparting high ionic conductivity to the electrolytic solution and facilitating the formation of a stable interfacial protective film, one or more selected from monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate are preferable.

[0114] The cyclic carbonate having a fluorine atom can be used alone or in combination of two or more in any ratio.

[0115] [1-4-2. Organic Compound Having Isocyanate Group] As the organic compound having an isocyanate group, which is one aspect of the auxiliary agent in the present embodiment, there is no particular limitation as long as it is an organic compound having at least one isocyanate group in the molecule. The number of isocyanate groups is preferably 1 or more and 4 or less, more preferably 2 or 3, and still more preferably 2 in one molecule.

[0116] Examples of the organic compound having an isocyanate group include monoisocyanate compounds such as methyl isocyanate, ethyl isocyanate, butyl isocyanate, vinyl isocyanate, propargyl isocyanate, cyclohexyl isocyanate, phenyl isocyanate, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate; diisocyanate compounds such as monomethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, 1,4-phenylene diisocyanate, 1,3-diisocyanatopropane, 1,3-bis(isocyanatomethyl)cyclohexane, carbonyl diisocyanate, 1,4-diisocyanato-2-fluorobutane; and the like. Particularly, from the viewpoint of forming a stable interface protection film, an organic compound having at least two isocyanate groups is preferable, hexamethylene diisocyanate and 1,3-bis(isocyanatomethyl)cyclohexane are more preferable, and 1,3-bis(isocyanatomethyl)cyclohexane is still more preferable.

[0117] [1-4-3. Organic Compound Having an Isocyanuric Acid Skeleton] As the organic compound having an isocyanuric acid skeleton, which is one aspect of the auxiliary agent in the present embodiment (hereinafter, also referred to as "isocyanurate compound"), there is no particular limitation as long as it is an organic compound having at least one isocyanuric acid skeleton in the molecule. Examples of the organic compound having an isocyanuric acid skeleton include the following compounds.

[0118] [Chemical Formula]

[0119] As an isocyanurate compound, particularly from the viewpoint of forming a stable interface protection film, an isocyanurate compound having a saturated or unsaturated aliphatic hydrocarbon group which may have a halogen atom is preferable, an isocyanurate compound having an unsaturated aliphatic hydrocarbon group containing a carbon-carbon unsaturated bond at the terminal is more preferable, and triallyl isocyanurate is even more preferable.

[0120] [1-4-4. Sulfur-containing organic compound] The sulfur-containing organic compound which is one aspect of the auxiliary agent in the present embodiment is not particularly limited as long as it is an organic compound having at least one sulfur atom (S) in the molecule. Preferably, it is an organic compound having at least one S=O bond, and more preferably, ester compounds having an S=O bond such as linear sulfonic acid esters, cyclic sulfonic acid esters, linear sulfuric acid esters, cyclic sulfuric acid esters, linear sulfite esters, and cyclic sulfite esters are exemplified. However, those corresponding to the anion-containing compounds having an S=O bond and an S-X bond are not "sulfur-containing organic compounds" but are included in the above-mentioned "anion-containing compounds having an S=O bond and an S-X bond".

[0121] Examples of sulfur-containing organic compounds include chain sulfonic acid esters such as alkyl disulfonic acid esters like methyl fluorosulfonate, methyl methanesulfonate, ethyl methanesulfonate, busulfan, methyl methanesulfonyloxyacetate, methyl vinylsulfonate, allyl vinylsulfonate, propargyl allylsulfonate, methoxycarbonylmethyl methanedisulfonate, ethoxycarbonylmethyl methanedisulfonate, methoxycarbonylmethyl 1,3 - butanedisulfonate, ethoxycarbonylmethyl 1,3 - butanedisulfonate, 1 - methoxycarbonylethyl 1,3 - butanedisulfonate, 1 - ethoxycarbonylethyl 1,3 - butanedisulfonate; cyclic sulfonic acid esters such as 1,3 - propanesultone, 1 - fluoro - 1,3 - propanesultone, 1 - methyl - 1,3 - propanesultone, 1 - propene - 1,3 - sultone, 2 - propene - 1,3 - sultone, 1 - fluoro - 1 - propene - 1,3 - sultone, 1 - methyl - 1 - propene - 1,3 - sultone, 1,3 - butanesultone, 2,4 - butanesultone, 1,4 - butanesultone, 1,5 - pentanesultone, methylene methanedisulfonate, ethylene methanedisulfonate, 2,2 - dioxide - 1,2 - oxathiolan - 4 - yl acetate; chain sulfuric acid esters such as dimethyl sulfate, ethyl methyl sulfate, diethyl sulfate; cyclic sulfuric acid esters such as 1,2 - ethylene sulfate, 1,2 - propylene sulfate, 1,3 - propylene sulfate, 1,2 - butylene sulfate; chain sulfite esters such as dimethyl sulfite, ethyl methyl sulfite, diethyl sulfite; cyclic sulfite esters such as 1,2 - ethylene sulfite, 1,2 - propylene sulfite, 1,3 - propylene sulfite, 1,2 - butylene sulfite; cyclic sulfones such as 1,1 - dioxidetetrahydrothiophen - 3 - yl methanesulfonate, 1,1 - dioxide - 2,3 - dihydrothiophen - 3 - yl methanesulfonate;Sulfonic acid esters such as butane-2,3-diyl dimethanesulfonate, butane-1,4-diyl dimethanesulfonate or methylene methanedisulfonate, and vinyl sulfone compounds such as divinyl sulfone, 1,2-bis(vinylsulfonyl)ethane or bis(2-vinylsulfonylethyl) ether; etc. are included.

[0122] Particularly, from the viewpoint of forming a stable interfacial protective film, chain or cyclic sulfonic acid esters, cyclic sulfuric acid esters, or cyclic sulfurous acid esters are more preferable, cyclic sulfonic acid esters or cyclic sulfuric acid esters are particularly preferable, and 1,3-propanesultone, methylene methanedisulfonate, and 1,2-ethylene sulfate are most preferable.

[0123] [1-4-5. Phosphorus-containing organic compounds] The phosphorus-containing organic compound, which is one aspect of the auxiliary agent in this embodiment, is not particularly limited as long as it is a compound having at least one phosphorus atom in the molecule. However, those corresponding to anion-containing compounds having P=O bonds and P-F bonds are not "phosphorus-containing organic compounds" but are included in the above-mentioned "anion-containing compounds having P=O bonds and P-F bonds".

[0124] Examples of the phosphorus-containing organic compound include trimethyl phosphate, tributyl phosphate, trioctyl phosphate, tris(2,2,2-trifluoroethyl) phosphate, ethyl 2-(diethoxyphosphoryl)acetate, and 2-propynyl 2-(diethoxyphosphoryl)acetate.

[0125] Particularly, ethyl 2-(diethoxyphosphoryl)acetate or 2-propynyl 2-(diethoxyphosphoryl)acetate is preferable, and 2-propynyl 2-(diethoxyphosphoryl)acetate is more preferable.

[0126] [1-4-6. Silicon-containing compounds] The silicon-containing compound, which is one aspect of the auxiliary agent in the present embodiment, is not particularly limited as long as it is a compound having at least one silicon atom in the molecule. Examples of the silicon-containing compound include boric acid compounds such as tris(trimethylsilyl) borate, tris(trimethoxysilyl) borate, tris(triethylsilyl) borate, and tris(dimethylvinylsilyl) borate; phosphoric acid compounds such as tris(trimethylsilyl) phosphate, tris(triethylsilyl) phosphate, tris(triphenylsilyl) phosphate, tris(trimethoxysilyl) phosphate, and tris(dimethylvinylsilyl) phosphate; phosphorous acid compounds such as tris(trimethylsilyl) phosphite, tris(triethylsilyl) phosphite, tris(triphenylsilyl) phosphite, tris(trimethoxysilyl) phosphite, and tris(dimethylvinylsilyl) phosphite; sulfonic acid compounds such as trimethylsilyl methanesulfonate and trimethylsilyl tetrafluoromethanesulfonate; silane compounds such as tetramethylsilane, trimethylvinylsilane, dimethyldivinylsilane, methyltrivinylsilane, and tetravinylsilane; disilane compounds such as hexamethyldisilane, hexaethyldisilane, 1,1,2,2-tetramethyldisilane, and 1,2-diphenyltetramethyldisilane; disiloxane compounds such as hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, and 1,1,3,3-tetramethyl-1,3-diphenyldisiloxane; and the like.

[0127] Particularly, from the viewpoint of forming a stable interface protection film, disilane compounds and disiloxane compounds are preferable, disiloxane compounds are more preferable, hexamethyldisiloxane and 1,3-divinyltetramethyldisiloxane are even more preferable, and 1,3-divinyltetramethyldisiloxane is particularly preferable.

[0128] [1-4-7. Aromatic Compound] As the aromatic compound which is one aspect of the auxiliary agent in the present embodiment, there is no particular limitation as long as it is a compound having an aromatic group in the molecule. Examples of the aromatic compound include aromatic compounds having a branched alkyl group such as cyclohexylbenzene, tert-butylbenzene, tert-amylbenzene or 1-fluoro-4-tert-butylbenzene; aromatic compounds such as biphenyl, terphenyl (o-, m-, p-isomers), fluorobenzene, methyl phenyl carbonate, ethyl phenyl carbonate or diphenyl carbonate; and the like.

[0129] In particular, biphenyl, terphenyl (o-, m-, p-isomers), fluorobenzene, cyclohexylbenzene, tert-butylbenzene, and tert-amylbenzene are more preferable, and biphenyl, o-terphenyl, fluorobenzene, cyclohexylbenzene and tert-amylbenzene are more preferable.

[0130] [Organic compound having a cyano group] As the organic compound having a cyano group which is one aspect of the auxiliary agent in the present embodiment, there is no particular limitation as long as it is an organic compound having at least one cyano group in the molecule. Examples of the organic compound having a cyano group include organic compounds having 1 cyano group in the molecule such as acetonitrile, propionitrile, butyronitrile, pentanenitrile, hexanenitrile, decanenitrile, undecanenitrile, dodecanenitrile, cyclohexanecarbonitrile, acrylonitrile, methacrylonitrile, crotononitrile; organic compounds having 2 cyano groups in the molecule such as succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, sebaconitrile, methyl malononitrile, ethyl malononitrile, bicyclohexyl-1,1-dicarbonitrile, 1,4-dicyanopentane, 1,2-dicyanobenzene; organic compounds having 3 cyano groups in the molecule such as 1,2,3-propanetricarbonitrile, 1,2,3-tris(2-cyanoethoxy)propane, 1,3,5-cyclohexanetricarbonitrile, 1,3,5-benzenetricarbonitrile; and the like.

[0131] From the viewpoint of forming a particularly stable interfacial protective film, an organic compound having two cyano groups is preferable, succinonitrile and adiponitrile are more preferable, and adiponitrile is even more preferable.

[0132] [1-4-9. Fluorine-free carboxylic acid ester] The fluorine-free carboxylic acid ester, which is one aspect of the auxiliary agent in this embodiment, is not particularly limited as long as it is a carboxylic acid ester having no fluorine atom in the molecule. Preferably, it is a fluorine-free chain carboxylic acid ester, and more preferably, it is a fluorine-free saturated chain carboxylic acid ester. The total number of carbon atoms of the fluorine-free chain carboxylic acid ester is preferably 3 to 7, more preferably 3 to 6, and even more preferably 4 to 5. Here, the total number of carbon atoms is preferably 3 or more, more preferably 4 or more, preferably 7 or less, more preferably 6 or less, and even more preferably 5 or less.

[0133] Examples of the chain carboxylic acid ester include methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, n-butyl propionate, methyl pivalate, ethyl pivalate, n-propyl pivalate, isopropyl pivalate, n-butyl pivalate, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, methyl crotonate, ethyl crotonate, methyl 2-propynoate, and the like. In particular, from the viewpoint of improving the output characteristics of the battery, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, and n-propyl propionate are preferable, and methyl propionate is more preferable.

[0134] [1-4-10. Cyclic ether compound] As the cyclic ether compound which is one aspect of the auxiliary agent in the present embodiment, there is no particular limitation as long as it is a compound having one or more ether bonds in the molecule. Examples of the cyclic ether compound include cyclic acetal compounds such as 1,3-dioxolane, 1,3-dioxane, or 1,3,5-trioxane.

[0135] As the cyclic ether compound, cyclic acetal compounds are particularly preferable, 1,3-dioxolane or 1,3-dioxane is preferable, and 1,3-dioxane is more preferable.

[0136] [1-4-11. Acid Anhydride] As the acid anhydride which is one aspect of the auxiliary agent in the present embodiment, there is no particular limitation as long as it is an acid anhydride having a "C(=O)-O-C(=O) group", "C(=O)-O-S(=O) 2 group", or "S(=O) 2 -O-S(=O) 2 group" in the molecule. Examples of the acid anhydride include chain carboxylic acid anhydrides such as acetic anhydride, acrylic anhydride, methacrylic anhydride, cyclohexanecarboxylic anhydride, propiolic anhydride, benzoic anhydride, fluoroacetic anhydride, 4-fluorobenzoic anhydride, and acetic propionic anhydride; succinic anhydride, maleic anhydride, citraconic anhydride, glutaric anhydride, itaconic anhydride, fluoro succinic anhydride, allyl succinic anhydride, 1,2-oxathiolane-5-one 2,2-dioxide, 1,2,6-oxadithiane 2,2,6,6-tetraoxide, and the like.

[0137] Particularly, from the viewpoint of forming a stable interfacial protective film, methacrylic anhydride, succinic anhydride, maleic anhydride, and allyl succinic anhydride are preferable, and succinic anhydride or allyl succinic anhydride is more preferable.

[0138] [1-4-12. Compound Containing Triple Bond] As the triple bond-containing compound which is one aspect of the auxiliary agent in the present embodiment, there is no particular limitation as long as it is a compound having at least one triple bond in the molecule. Examples of the triple bond-containing compound include 2-propynyl methyl carbonate, 2-propynyl acetate, 2-propynyl formate, 2-propynyl methacrylate, 2-propynyl methanesulfonate, 2-propynyl vinyl sulfonate, 2-propynyl 2-(methanesulfonyloxy)propionate, di(2-propynyl) oxalate, 2-butyne-1,4-diyl dimethanesulfonate, and 2-butyne-1,4-diyl diformate.

[0139] In particular, 2-propynyl methyl carbonate, 2-propynyl methacrylate, 2-propynyl methanesulfonate, 2-propynyl vinyl sulfonate, di(2-propynyl) oxalate, and 2-butyne-1,4-diyl dimethanesulfonate are preferable, and 2-propynyl methanesulfonate, 2-propynyl vinyl sulfonate, di(2-propynyl) oxalate, and 2-butyne-1,4-diyl dimethanesulfonate are more preferable.

[0140] [1-4-13. Phosphazene compound] As the phosphazene compound which is one aspect of the auxiliary agent in the present embodiment, there is no particular limitation as long as it is a compound having an "N=P-N group" in the molecule. Examples of the phosphazene compound include cyclic phosphazene compounds such as methoxypentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, or ethoxyheptafluorocyclotetraphosphazene.

[0141] In particular, cyclic phosphazene compounds such as methoxypentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, or phenoxypentafluorocyclotriphosphazene are preferable, and methoxypentafluorocyclotriphosphazene or ethoxypentafluorocyclotriphosphazene is more preferable.

[0142] [Mass ratio of the main salt and the auxiliary agent] When the non-aqueous electrolyte according to the present embodiment contains an auxiliary agent other than a specific carbonate compound as the auxiliary agent, the mass ratio of the content of the auxiliary agent to the content of the main salt contained in the electrolyte in the non-aqueous electrolyte, that is, the mass ratio represented by auxiliary agent [g] / main salt [g], is usually 0.00005 to 0.5, preferably 0.0001 to 0.5, more preferably 0.001 to 0.45, still more preferably 0.01 to 0.4, even more preferably 0.02 to 0.4, and particularly preferably 0.025 to 0.35. Here, the above mass ratio is usually 0.00005 or more, preferably 0.0001 or more, more preferably 0.001 or more, still more preferably 0.01 or more, even more preferably 0.02 or more, and particularly preferably 0.025 or more, and is usually 0.5 or less, preferably 0.45 or less, more preferably 0.4 or less, still more preferably 0.35 or less. Note that the contents of the main salt and the auxiliary agent mean the total contents when two or more kinds of the main salt and the auxiliary agent are contained, respectively. Further, depending on the content of the specific anion-containing compound, the content of the specific anion-containing compound is also included in the main salt or the auxiliary agent described above. If the mass ratio is within the above range, battery characteristics, particularly an increase rate of internal resistance, can be suppressed. The reason for this is not clear, but it is considered that within the range of the above mass ratio, by containing the auxiliary agent and the main salt, an interfacial protective film is formed on the electrode, and side reactions of the electrolyte in the battery system are minimized.

[0143] 《2. Non-aqueous electrolyte battery》 The energy device according to the present embodiment includes a negative electrode, a positive electrode, and a non-aqueous electrolyte. The non-aqueous electrolyte contains a non-aqueous solvent, an electrolyte, and the compound represented by the above formula (1), and the electrolyte further contains the specific anion-containing compound. As one aspect of the above energy device, a non-aqueous electrolyte battery can be mentioned. Hereinafter, as the energy device, a non-aqueous electrolyte battery will be used as an example to explain the details.

[0144] The non-aqueous electrolyte battery according to this embodiment includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. The non-aqueous electrolyte is the non-aqueous electrolyte described in "1. Non-aqueous electrolyte". That is, the non-aqueous electrolyte contains a non-aqueous solvent, an electrolyte, and the compound represented by the above formula (1). Further, the electrolyte contains the specific anion-containing compound. Here, both the positive electrode and the negative electrode can occlude and release metal ions.

[0145] The non-aqueous electrolyte battery is preferably a non-aqueous electrolyte secondary battery. Among the components of the non-aqueous electrolyte secondary battery, except for the above non-aqueous electrolyte, a lithium-ion secondary battery will be taken as an example and described below.

[0146] [2-1. Positive electrode] The positive electrode includes a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer contains a positive electrode active material capable of occluding and releasing lithium ions. Further, the positive electrode active material layer may be formed on at least a part of the surface of the current collector.

[0147] [2-1-1. Positive electrode active material] The positive electrode active material used for the positive electrode is not particularly limited as long as it can electrochemically occlude and release metal ions. For example, lithium transition metal-based compounds can be mentioned. The positive electrode active material (lithium transition metal-based compound) used for the positive electrode will be described below.

[0148] [2-1-1-1. Lithium transition metal-based compound] The lithium transition metal-based compound is a compound having a structure capable of desorbing and inserting lithium ions. For example, sulfides, phosphate compounds, silicate compounds, borate compounds, lithium transition metal composite oxides, etc. can be mentioned. Among them, phosphate compounds and lithium transition metal composite oxides are preferable, and lithium transition metal composite oxides are more preferable.

[0149] Examples of the lithium transition metal composite oxide include those belonging to a spinel structure, an olivine structure that enables three-dimensional diffusion of lithium ions, and a layered structure that enables two-dimensional diffusion of lithium ions. Among them, from the viewpoint of improving the battery capacity, a lithium transition metal composite oxide having a layered structure is preferable.

[0150] The lithium transition metal composite oxide having a spinel structure is generally represented by the following composition formula (1). Li x’ M’ y’ O 4 ···(1) (In formula (1), 0.8 ≦ x’ ≦ 1.5, 1.9 ≦ y’ ≦ 2.1, and M’ contains at least one transition metal element.)

[0151] Specific examples of the lithium transition metal composite oxide having a spinel structure include LiMn 2 O 4 , LiCoMnO 4 , LiNi 0.5 Mn 1.5 O 4 , LiCoVO 4 and the like.

[0152] The lithium transition metal composite oxide having an olivine structure is generally represented by the following composition formula (2). Li x” M” y” PO 4 ···(2) (In formula (2), 0.8 ≦ x” ≦ 1.5, 0.9 ≦ y” ≦ 1.1, and M” contains at least one transition metal element.)

[0153] Examples of M” include Fe, Ni, Co, Mn and the like. Specific examples of the lithium transition metal composite oxide having an olivine structure include LiFePO 4、 and the like.

[0154] The lithium transition metal composite oxide having a layered structure is generally represented by the following composition formula (3). Li1+x M y O 2 ···(3) (In formula (3), -0.2 ≦ x ≦ 0.5, 0.5 ≦ y ≦ 1.1, and M contains at least one transition metal element.)

[0155] As the lithium transition metal composite oxide having a layered structure, specifically, LiCoO 2 , LiNiO 2 , LiNi 0.90 Co 0.05 Mn 0.05 O 2 , LiNi 0.85 Co 0.10 Al 0.05 O 2 , LiNi 0.80 Co 0.15 Al 0.05 O 2 , LiNi 0.33 Co 0.33 Mn 0.33 O 2 , Li 1.05 Ni 0.33 Co 0.33 Mn 0.33 O 2 , LiNi 0.5 Co 0.2 Mn 0.3 O 2 , Li 1.05 Ni 0.5 Co 0.2 Mn 0.3 O 2 , LiNi 0.6 Co 0.2 Mn 0.2 O 2 , LiNi 0.8 Co 0.1 Mn 0.1 O 2 , Li[Li 1 / 3 Mn 2 / 3 O 2 , and their solid solutions, etc. can be mentioned.

[0156] Among the lithium transition metal composite oxides having a layered structure, from the viewpoint of increasing the capacity, it is preferable that it is a lithium transition metal composite oxide represented by the following composition formula (4). Li1+y M 1 O 2 (4) (In formula (4), -0.2 ≤ y ≤ 0.5, and M 1 represents a plurality of elements including at least Ni element, and the molar ratio (Ni / M 1 of the Ni element to the content of all elements contained in M 1 ) is 0.30 to 1.0.)

[0157] In the above composition formula (4), the molar ratio (Ni / M 1 ) is 0.30 or more, preferably 0.40 or more, more preferably 0.50 or more, and preferably 1.0 or less, more preferably 0.90 or less. And the molar ratio (Ni / M 1 ) is 0.30 or more and 1.0 or less, preferably 0.40 or more and 0.90 or less, more preferably 0.50 or more and 0.90 or less.) When the molar ratio (Ni / M 1 ) is within this range, the compound represented by the general formula (I) is likely to form an interfacial protective film on the positive electrode, and by suppressing the side reaction between the positive electrode and the non-aqueous electrolyte, the increase rate of the internal resistance after high-temperature storage of the non-aqueous electrolyte battery can be suppressed.)

[0158] Specific examples of the lithium transition metal oxide having a layered structure represented by the composition formula (4) include LiNiO 2 , LiNi 0.85 Co 0.10 Al 0.05 O 2 , LiNi 0.80 Co 0.15 Al 0.05 O 2 , LiNi 0.3 Co 0.3 Mn 0.3 O 2 , LiNi 0.5 Co 0.2 Mn 0.3 O 2 , Li 1.05 Ni 0.5 Co 0.2 Mn 0.3 O 2 , LiNi 0.6 Co 0.2 Mn0.2 O 2 、 LiNi 0.8 Co 0.1 Mn 0.1 O 2 、 LiNi 0.91 Co 0.06 Mn 0.03 O 2 、 LiNi 0.91 Co 0.06 Al 0.03 O 2 、 LiNi 0.90 Co 0.03 Al 0.07 O 2 、 Li 1.00 Ni 0.61 Co 0.20 Mn 0.19 O 2 etc. can be mentioned.

[0159] Among lithium transition metal compounds, from the viewpoint of improving battery capacity, lithium transition metal composite oxides having a layered structure are preferred, and lithium transition metal composite oxides represented by the following composition formula (5) are more preferred. Li a1 Ni b1 M 2 c1 O 2 (5) (In formula (5), M 2 represents at least one element selected from the group consisting of Co, Mn, Al, Mg, Zr, Fe, Ti, and Er, 50.80 ≦ a1 ≦ 1.10, 0.30 ≦ b1 ≦ 0.98, 0.00 ≦ c1 ≦ 0.70, and 0.90 ≦ b1 + c1 ≦ 1.10.)

[0160] In composition formula (5), b1 is preferably 0.40 or more and 0.98 or less, more preferably 0.45 or more and 0.98 or less, and still more preferably 0.50 or more and 0.98 or less. Here, b1 is 0.30 or more, preferably 0.40 or more, more preferably 0.45 or more, still more preferably 0.50 or more, and is 0.98 or less.

[0161] Specific examples of the lithium transition metal oxide having a layered structure represented by composition formula (5) include LiNi 0.90 Co0.05 Mn 0.05 O 2 、 LiNi 0.85 Co 0.10 Al 0.05 O 2 、 LiNi 0.80 Co 0.15 Al 0.05 O 2 、 LiNi 0.3 Co 0.3 Mn 0.3 O 2 、 LiNi 0.5 Co 0.2 Mn 0.3 O 2 、 Li 1.05 Ni 0.5 Co 0.2 Mn 0.3 O 2 、 LiNi 0.6 Co 0.2 Mn 0.2 O 2 、 LiNi 0.8 Co 0.1 Mn 0.1 O 2 、 LiNi 0.91 Co 0.06 Mn 0.03 O 2 、 LiNi 0.91 Co 0.06 Al 0.03 O 2 、 LiNi 0.90 Co 0.03 Al 0.07 O 2 、 Li 1.00 Ni 0.61 Co 0.20 Mn 0.19 O 2 etc. can be mentioned.

[0162] In particular, from the viewpoint of the structural stability of the lithium transition metal composite oxide, it is preferably a lithium transition metal composite oxide represented by the following composition formula (6). Li a2 Ni b2 Co c2 M 3 d2 O 2 (6) (In formula (6), M 3represents at least one element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti, and Er, where 0.80 ≦ a2 ≦ 1.10, 0.30 ≦ b2 ≦ 0.98, 0.01 ≦ c2 ≦ 0.70, and 0.01 ≦ d2 ≦ 0.60, and 0.90 ≦ b2 + c2 + d2 ≦ 1.10.)

[0163] In the above compositional formula (6), b2 is 0.30 or more and 0.98 or less, preferably 0.40 or more and 0.98 or less, more preferably 0.45 or more and 0.98 or less, and even more preferably 0.50 or more and 0.98 or less. Here, b2 is preferably 0.40 or more, more preferably 0.45 or more, and even more preferably 0.50 or more.) Also, in the above compositional formula (6), d2 is preferably 0.01 or more and 0.60 or less, and more preferably 0.10 or more and 0.60 or less. Here, d2 is preferably 0.01 or more, more preferably 0.10 or more, and also preferably 0.60 or less.)

[0164] Preferable examples of the lithium transition metal composite oxide represented by the above compositional formula (6) include LiNi 0.90 Co 0.05 Mn 0.05 O 2 、LiNi 0.85 Co 0.10 Al 0.05 O 2 、LiNi 0.80 Co 0.15 Al 0.05 O 2 、LiNi 0.3 Co 0.3 Mn 0.3 O 2 、LiNi 0.5 Co 0.2 Mn 0.3 O 2 、Li 1.05 Ni 0.5 Co 0.2 Mn 0.3 O 2 、LiNi 0.6 Co 0.2 Mn 0.2 O 2 、LiNi 0.8 Co 0.1 Mn 0.1 O 2, LiNi 0.91 Co 0.06 Mn 0.03 O 2 , LiNi 0.91 Co 0.06 Al 0.03 O 2 , LiNi 0.90 Co 0.03 Al 0.07 O 2 , LiNi 0.61 Co 0.20 Mn 0.19 O 2 etc. can be mentioned.

[0165] In the above compositional formula (4) or (5), from the viewpoint of enhancing the structural stability of the lithium transition metal oxide and suppressing the structural deterioration during repeated charge and discharge, M 1 or M 2 preferably contains Mn or Al, and more preferably contains Mn. In the above compositional formula (6), from the viewpoint of enhancing the structural stability of the lithium transition metal composite oxide and suppressing the structural deterioration during repeated charge and discharge, M 3 preferably contains Mn or Al, and more preferably contains Mn.

[0166] More specifically, the positive electrode active material is more preferably at least one selected from the group consisting of lithium-cobalt composite oxide, lithium-cobalt-nickel composite oxide, lithium-manganese composite oxide, lithium-cobalt-manganese composite oxide, lithium-nickel composite oxide, lithium-nickel-manganese composite oxide, and lithium-cobalt-nickel-manganese composite oxide. The identification and content measurement of the positive electrode active material are performed by ICP emission spectrometry after wet decomposition of the sample.

[0167] [2-1-1-2. Introduction of foreign elements] The lithium transition metal oxide may further contain an element (foreign element) other than the elements contained in any of the above compositional formulas (1) to (5).

[0168] [2-1-1-3. Surface coating] As the positive electrode, one in which a substance (surface adherent substance) having a composition different from that of the positive electrode active material adheres to the surface of the positive electrode active material may be used. Examples of the surface adherent substance include oxides such as aluminum oxide, sulfates such as lithium sulfate, carbonates such as lithium carbonate, and the like. These surface adherent substances can be adhered to the surface of the positive electrode active material, for example, by a method of dissolving or suspending them in a solvent, impregnating and adding them to the positive electrode active material, and drying.

[0169] The amount of the surface adherent substance is preferably 1 μmol / g to 1 mmol / g, more preferably 10 μmol / g to 1 mmol / g with respect to the positive electrode active material. Here, the amount of the surface adherent substance is preferably 1 μmol / g or more, more preferably 10 μmol / g or more, and usually preferably 1 mmol / g or less. In this specification, one in which the surface adherent substance adheres to the surface of the positive electrode active material is also referred to as the "positive electrode active material".

[0170] [2-1-1-4. Blend] The positive electrode active material can be used alone or in combination of two or more in any ratio.

[0171] [2-1-2. Structure and manufacturing method of positive electrode] The production of the positive electrode having the positive electrode active material can be carried out by a conventional method. That is, a method of dry-mixing the positive electrode active material, a binder, and, if necessary, a conductive material, a thickener, etc. into a sheet shape and pressing it onto a positive electrode current collector, or dissolving or dispersing these materials in a liquid medium such as an aqueous solvent or an organic solvent to form a slurry, applying this to the positive electrode current collector, and drying to form a positive electrode active material layer on the current collector, whereby a positive electrode can be obtained by a coating method. Further, for example, the positive electrode active material may be roll-formed into a sheet electrode or pelletized into a pellet electrode by compression molding. Hereinafter, the case where the slurry is sequentially applied and dried to the positive electrode current collector will be described.

[0172] [2-1-2-1. Content of positive electrode active material] The positive electrode consists of a current collector and a positive electrode active material layer formed on the current collector and containing a positive electrode active material. The content of the positive electrode active material in the positive electrode active material layer is usually 80% by mass or more and 99.5% by mass or less.

[0173] [2-1-2-2. Electrode density] The positive electrode active material layer obtained by applying and drying the positive electrode active material together with a binder, a conductive material, etc. is preferably densified by hand pressing, roller pressing, etc. in order to increase the packing density of the positive electrode active material. The electrode structure when the positive electrode active material is polarized is not particularly limited, but the density of the positive electrode active material layer present on the current collector is usually 1.5 g / cm 3 or more and 4.5 g / cm 3 or less.

[0174] [2-1-2-3. Binder] When forming the positive electrode active material layer by a coating method, the type of the binder is not particularly limited as long as it is a material that is dissolved or dispersed in the liquid medium for the slurry. Examples of the binder include fluorine-based resins such as polyvinyl fluoride, polyvinylidene fluoride, and polytetrafluoroethylene in terms of weather resistance, chemical resistance, heat resistance, flame retardancy, etc.; CN group-containing polymers such as polyacrylonitrile and polyvinylidene cyanide are preferable. In addition, mixtures, modified products, derivatives, random copolymers, alternating copolymers, graft copolymers, block copolymers, etc. of the above polymers can also be used. The binder can be used alone or in combination of two or more in any ratio.

[0175] When using a resin as the binder, the weight average molecular weight of the resin is arbitrary as long as the effects of the present invention are not impaired, and is usually 10,000 or more and 3,000,000 or less. When the molecular weight is within this range, the strength of the electrode is improved and the formation of the electrode can be suitably carried out.

[0176] The content of the binder in the positive electrode active material layer is usually 0.1% by mass or more and 20% by mass or less.

[0177] [2-1-2-4. Conductive Material] As the conductive material, known conductive materials can be arbitrarily used. Specific examples thereof include metal materials such as copper and nickel; graphite (graphite) such as natural graphite and artificial graphite; carbon black such as acetylene black; carbon-based materials such as amorphous carbon such as needle coke; etc. The conductive material can be used alone or in combination of two or more in any ratio.

[0178] The conductive material is usually used so as to be contained in the positive electrode active material layer in an amount of 0.01% by mass or more and 20% by mass or less.

[0179] [2-1-2-5. Current Collector] The material of the current collector for holding the positive electrode active material is not particularly limited, and known materials can be arbitrarily used. Specific examples include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum, and aluminum is preferred.

[0180] Examples of the shape of the current collector include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punched metal, and foamed metal. Among these, metal foil or metal thin film is preferred. The metal thin film may be appropriately formed in a mesh shape.

[0181] When the shape of the current collector of the positive electrode is plate-like or film-like, etc., the thickness of the current collector is arbitrary, but it is usually 1 μm or more and 1 mm or less.

[0182] [2-1-2-6. Thickness of Positive Electrode Plate] The thickness of the positive electrode (positive electrode plate) is not particularly limited, but from the viewpoints of high capacity and high output, the thickness of the positive electrode active material layer obtained by subtracting the thickness of the current collector from the thickness of the positive electrode plate is usually 10 μm or more and 500 μm or less with respect to one surface of the current collector. The positive electrode active material layer may be formed on one surface or both surfaces of the current collector.

[0183] [2-1-2-7. Surface Coating of Positive Electrode Plate] The positive electrode plate may be one having a substance with a composition different from that of the positive electrode active material attached to its surface, and as such a substance, the same substance as the surface-attached substance that may be attached to the surface of the positive electrode active material is used.

[0184] [2-2. Negative electrode] The negative electrode includes a current collector and a negative electrode active material layer formed on the current collector. The negative electrode active material layer contains a negative electrode active material capable of occluding and releasing lithium ions. Also, the negative electrode active material layer may be formed on at least a part of the surface of the current collector.

[0185] [2-2-1. Negative electrode active material] The negative electrode active material used for the negative electrode is not particularly limited as long as it can electrochemically occlude and release metal ions.

[0186] Specific examples include (i) carbon-based materials, (ii) materials containing a metal element and / or a metalloid element that can be alloyed with Li, (iii) lithium-containing metal composite oxide materials, and (iv) mixtures of the above (i) to (iii), etc. Among these, in terms of having good cycle characteristics, safety, and further excellent continuous charging characteristics, (i) carbon-based materials, (ii) materials containing a metal element and / or a metalloid element that can be alloyed with Li, and (iv) mixtures of the above (i) to (iii) are preferable, and as (iv), a mixture of a material containing a metal element and / or a metalloid element that can be alloyed with Li and graphite is more preferable. These can be used alone or in combination of two or more in any ratio.

[0187] [2-2-1-1. Carbon-based materials] (i) Examples of carbon-based materials include natural graphite, artificial graphite, amorphous carbon, carbon-coated graphite, graphite-coated graphite, and resin-coated graphite, etc. Among these, natural graphite is preferable. The carbon-based materials can be used alone or in combination of two or more in any ratio.

[0188] Examples of natural graphite include flake graphite, flaky graphite, and / or graphite particles obtained by subjecting these graphites to treatments such as spheroidization and densification. Among these, spherical or ellipsoidal graphite particles obtained by spheroidization treatment are preferred from the viewpoints of particle packing properties or charge-discharge rate characteristics. The average particle diameter (d50) of the graphite particles is usually 1 μm or more and 100 μm or less. Here, the average particle diameter (d50) is the volume-based average particle diameter (median diameter) determined by the laser diffraction / scattering method.

[0189] [2-2-1-2. Physical Properties of Carbon-Based Materials] The carbon-based material as the negative electrode active material preferably satisfies at least one of the physical property and shape characteristics shown in the following (1) to (4), and more preferably satisfies a plurality of items simultaneously. (1) X-ray Diffraction Parameters The d value (interlayer distance) of the lattice plane (002 plane) determined by X-ray diffraction of the carbon-based material using the Gakushin method is usually 0.335 nm or more and 0.360 nm or less. Also, the crystallite size (Lc) of the carbon-based material determined by X-ray diffraction using the Gakushin method is 1.0 nm or more. (2) Volume-Based Average Particle Diameter The volume-based average particle diameter of the carbon-based material is the volume-based average particle diameter (median diameter) determined by the laser diffraction / scattering method, and is usually 1 μm or more and 100 μm or less. (3) Raman R Value, Raman Half-Width The Raman R value of the carbon-based material is a value measured using the argon ion laser Raman spectroscopy method, and is usually 0.01 or more and 1.5 or less. Also, the Raman half-width of the carbon-based material near 1580 cm -1 is not particularly limited, but is usually 10 cm -1 or more and 100 cm -1 or less. (4) BET Specific Surface Area The BET specific surface area of the carbon-based material is the value of the specific surface area measured using the BET method, and is usually 0.1 m 2 ·g -1 or more and 100 m 2 ·g -1 or less.

[0190] The negative electrode active material may contain two or more carbon-based materials with different properties. The properties referred to here indicate one or more characteristics selected from the group of X-ray diffraction parameters, volume-based average particle size, Raman R value, Raman half-width, and BET specific surface area shown in the above (1) to (4).

[0191] Examples of containing two or more carbon-based materials with different properties include that the volume-based particle size distribution is not symmetric when centered on the median diameter, containing two or more carbon-based materials with different Raman R values, and different X-ray diffraction parameters, etc.

[0192] [2-2-1-3. Material containing a metal element and / or a metalloid element alloyable with Li] (ii) Any of the conventionally known materials containing a metal element and / or a metalloid element alloyable with Li can be used. From the viewpoints of capacity and cycle life, for example, it is preferably a metal or a metalloid selected from the group consisting of Sb, Si, Sn, Al, As, and Zn. When the material containing a metal element and / or a metalloid element alloyable with Li contains two or more metals, the material may be an alloy material composed of an alloy of these metals.

[0193] In addition, examples of the material containing a metal element and / or a metalloid element alloyable with Li include oxides, nitrides, carbides, etc. of the metal and / or the metalloid. The material may contain two or more metals alloyable with Li. Among these, materials containing Si element are preferred, and metallic Si (hereinafter also referred to as "Si") or Si-containing inorganic compounds are more preferred in terms of increasing the capacity. In this specification, Si or Si-containing inorganic compounds are collectively referred to as "Si compounds".

[0194] The content of the material containing a metal element and / or a metalloid element alloyable with Li with respect to the total mass of the negative electrode active material is preferably 0.1 to 25% by mass. In addition, a material containing a metal element and / or a metalloid element that can be alloyed with Li may already be alloyed with Li during the production of the negative electrode described later. As such a material, an Si compound is preferable in terms of achieving a high capacity.

[0195] The Si compound is an Si-containing inorganic compound such as SiO x (0 ≦ x ≦ 2) and the like. Examples of the metal compound alloyed with Li include Li y Si(0 < y ≦ 4.4), Li 2z SiO 2+z (0 < z ≦ 2) and the like.

[0196] As the Si compound, a silicon oxide (SiO x1 , 0 < x1 ≦ 2) is preferable in terms of having a larger theoretical capacity compared to graphite. Also, amorphous Si or nano-sized Si crystals are preferable in terms of allowing easy entry and exit of alkali ions such as lithium ions and enabling the attainment of a high capacity.

[0197] When a material containing a metal element and / or a metalloid element that can be alloyed with Li is in the form of particles, the average particle diameter (d 50 ) of the particles is usually 0.01 μm or more and 10 μm or less from the viewpoint of cycle life.

[0198] [2-2-1-4. Lithium-containing metal composite oxide material] (iii) The lithium-containing metal composite oxide material is not particularly limited as long as it can occlude and release lithium ions. Specifically, from the viewpoint of high current density charge-discharge characteristics, a lithium-containing metal composite oxide material containing titanium is preferable, a composite oxide of lithium and titanium (hereinafter also referred to as "lithium titanium composite oxide") is more preferable, and a lithium titanium composite oxide having a spinel structure is even more preferable because it greatly reduces the output resistance.

[0199] In addition, lithium and / or titanium in the lithium titanium composite oxide may be substituted with at least one element selected from the group consisting of other metal elements such as Al, Ga, Cu, and Zn.

[0200] As the lithium titanium composite oxide, Li 4 / 3 Ti 5 / 3 O 4 、Li 1 Ti 2 O 4 and Li 4 / 5 Ti 11 / 5 O 4 are preferred. Further, as the lithium titanium composite oxide in which a part of lithium and / or titanium is substituted with other elements, for example, Li 4 / 3 Ti 4 / 3 Al 1 / 3 O 4 is also preferred.

[0201] [2-2-1-5. Mixture of a material containing a metal element and / or a metalloid element alloyable with Li and graphite] (iv) is a mixture of the above (i) carbon-based material, (ii) material containing a metal element and / or a metalloid element alloyable with Li, and (iii) lithium-containing metal composite oxide material. Among them, a mixture of a material containing a metal element and / or a metalloid element alloyable with Li and graphite is preferred.

[0202] The mixture of a material containing a metal element and / or a metalloid element alloyable with Li and graphite may be a mixture in which the above (ii) material containing a metal element and / or a metalloid element alloyable with Li and graphite are mixed in a state of independent particles, or a composite in which the material containing a metal element and / or a metalloid element alloyable with Li is present on the surface or inside of the graphite particles.

[0203] The content ratio of the material containing a metal element and / or a metalloid element alloyable with Li to the total of the material containing a metal element and / or a metalloid element alloyable with Li and graphite is usually 1% by mass or more and 99% by mass or less.

[0204] More specifically, the negative electrode active material preferably contains at least one selected from the group consisting of silicon, simple metals, alloys and compounds thereof, tin, simple metals, alloys and compounds thereof, carbon-based materials, and lithium titanium composite oxides. The identification and content measurement of the negative electrode active material are performed by ICP emission spectrometry after the sample is alkali-melted.

[0205] [2-2-2. Configuration and manufacturing method of negative electrode] The negative electrode can be manufactured by any known method as long as the effects of the present invention are not impaired. For example, a binder, a liquid medium such as an aqueous solvent or an organic solvent, and, if necessary, a thickener, a conductive material, a filler, etc. are added to the negative electrode active material to form a slurry, which is applied to a current collector, dried, and then pressed to form a negative electrode active material layer.

[0206] [2-2-2-1. Content of negative electrode active material] The negative electrode consists of a current collector and a negative electrode active material layer containing a negative electrode active material formed on the current collector. The content of the negative electrode active material in the negative electrode active material layer is usually 80% by mass or more and 99.5% by mass or less.

[0207] [2-2-2-2. Electrode density] The negative electrode active material layer obtained by applying and drying the negative electrode active material together with a binder, a thickener, etc. is preferably densified by hand pressing, roller pressing, etc. in order to increase the packing density of the negative electrode active material. The electrode structure when the negative electrode active material is polarized is not particularly limited, but the density of the negative electrode active material layer present on the current collector is usually 1 g / cm 3 or more and 2.2 g / cm 3 or less.

[0208] [2-2-2-3. Binder] The binder may be any material that is stable with respect to the non-aqueous electrolyte and the liquid medium used during electrode manufacturing, and is not particularly limited. Specific examples thereof include rubbery high polymers such as styrene-butadiene rubber (SBR), isoprene rubber, butadiene rubber, fluororubber, acrylonitrile-butadiene rubber (NBR), ethylene-propylene rubber, etc., and fluorine-based high polymers such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, tetrafluoroethylene-ethylene copolymer, etc. These can be used alone or in combination of two or more in any ratio.

[0209] The content of the binder with respect to the negative electrode active material is usually 0.1% by mass or more and 20% by mass or less. In particular, when the binder contains a rubbery high polymer typified by SBR as a main component, the content of the binder with respect to the negative electrode active material is usually 0.1% by mass or more and 5% by mass or less. Also, when the binder contains a fluorine-based high polymer typified by polyvinylidene fluoride as a main component, the content of the binder with respect to the negative electrode active material is usually 1% by mass or more and 15% by mass or less.

[0210] [2-2-2-4. Thickening agent] The thickening agent is usually used to adjust the viscosity of the slurry. The thickening agent is not particularly limited, but specifically, carboxymethyl cellulose and its salts, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, etc. can be mentioned. These can be used alone or in combination of two or more in any ratio.

[0211] When using a thickening agent, the content of the thickening agent with respect to the negative electrode active material is usually 0.1% by mass or more and 5% by mass or less.

[0212] [2-2-2-5. Current collector] As the current collector for holding the negative electrode active material, known ones can be arbitrarily used. Examples of the current collector for the negative electrode include metal materials such as aluminum, copper, nickel, stainless steel, nickel-plated steel, etc., and copper is particularly preferable from the viewpoints of ease of processing and cost.

[0213] Examples of the shape of the current collector of the negative electrode include a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punched metal, a foamed metal, etc. Among these, a metal foil or a metal thin film is preferable. Note that the metal thin film may be appropriately formed in a mesh shape.

[0214] When the shape of the current collector of the negative electrode is plate-like, film-like, etc., the thickness of the current collector is arbitrary, but it is usually 1 μm or more and 1 mm or less.

[0215] [2-2-2-6. Thickness of the negative electrode plate] The thickness of the negative electrode (negative electrode plate) is designed according to the positive electrode (positive electrode plate) used and is not particularly limited. However, the thickness of the negative electrode active material layer obtained by subtracting the thickness of the current collector from the thickness of the negative electrode material is usually 15 μm or more and 300 μm or less.

[0216] [2-2-2-7. Surface coating of the negative electrode plate] As the negative electrode plate, one having a substance with a composition different from that of the negative electrode active material (surface adherent substance) adhered to its surface may be used. Examples of the surface adherent substance include oxides such as aluminum oxide, sulfates such as lithium sulfate, and carbonates such as lithium carbonate.

[0217] [2-3. Separator] A separator is usually interposed between the positive electrode and the negative electrode to prevent short circuit. In this case, the non-aqueous electrolyte is usually impregnated into this separator and used. There are no particular restrictions on the material and shape of the separator, and known ones can be arbitrarily adopted as long as the effects of the present invention are not impaired.

[0218] [2-4. Battery design] [2-4-1. Electrode group] The electrode group may be either a laminated structure formed by interposing the above positive electrode plate and negative electrode plate via the above separator, or a structure formed by winding the above positive electrode plate and negative electrode plate in a spiral shape via the above separator. The ratio of the volume of the electrode group to the internal volume of the battery (electrode group occupancy ratio) is usually 40% or more and 90% or less.

[0219] [2-4-2. Current collecting structure] When the electrode group has the above-described laminated structure, a structure formed by bundling the metal core portions of each electrode layer and welding them to the terminal is preferably used. A structure in which a plurality of terminals are provided in the electrode to reduce the resistance is also preferably used. When the electrode group has the above-described wound structure, a plurality of lead structures are provided for the positive electrode and the negative electrode, respectively, and by bundling them to the terminal, the internal resistance can be reduced.

[0220] [2-4-3. Protection element] As the protection element, a PTC (Positive Temperature Coefficient) element whose resistance increases along with heat generation due to an excessive current or the like, a thermal fuse, a thermistor, a valve (current cutoff valve) that cuts off the current flowing through the circuit due to a rapid increase in the internal pressure or internal temperature of the battery during abnormal heat generation, etc. can be used. It is preferable to select a protection element that does not operate under normal use conditions of high current, and it is more preferable to design such that abnormal heat generation or thermal runaway does not occur even without a protection element.

[0221] [2-4-4. Exterior body] The non-aqueous electrolyte battery is usually configured by housing the non-aqueous electrolyte, negative electrode, positive electrode, separator, etc. according to the present embodiment in an exterior body (exterior case). There is no limitation on this exterior body, and a known one can be arbitrarily adopted as long as the effects of the present invention are not impaired.

[0222] The material of the exterior case may be a substance that is stable with respect to the non-aqueous electrolyte used, and is not particularly limited. However, from the viewpoints of weight reduction and cost, metals such as iron, aluminum, and aluminum alloy, or a laminate film are preferably used. In particular, from the viewpoint of pressure resistance for operating the current cutoff valve, iron is preferable.

[0223] Examples of the exterior case using the above metals include those having a sealed structure formed by welding the metals together by laser welding, resistance welding, or ultrasonic welding, or those having a caulked structure using the above metals via a resin gasket.

[0224] [2-4-5. Shape] The shape of the exterior case of the non-aqueous electrolyte battery is also arbitrary, and may be, for example, any of a cylindrical shape, a rectangular shape, a laminated shape, a coin shape, a large size, etc.

Examples

[0225] The present invention will be described more specifically below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0226] <Compound> As the compound represented by the formula (1), the structures of Compound 1-1 and Compound 1-2 used in Examples and Comparative Examples are shown below.

[0227]

Chemical formula

[0228] <Examples 1 to 15, Comparative Examples 1 to 13> [Example 1] [Preparation of non-aqueous electrolyte] Under a dry argon atmosphere, in a mixture of ethylene carbonate (hereinafter referred to as EC) and ethyl methyl carbonate (hereinafter referred to as EMC) (volume ratio EC:EMC = 3:7), sufficiently dried LiPF 6 was dissolved as an electrolyte. Then, vinylene carbonate (hereinafter referred to as VC) was added to prepare Basic Electrolyte 1. Furthermore, 0.050 mass% of Compound 1-1 and LiPO 2 F 2 1.00 mass% were added to the above Basic Electrolyte 1 to prepare the non-aqueous electrolyte of Example 1. In this non-aqueous electrolyte, LiPF 6 was 13.66 mass%, EC was 29.78 mass%, EMC was 53.53 mass%, VC was 1.98 mass%, Compound 1-1 was 0.050 mass%, LiPO 2 F 2It contains 1.0% by mass. The ratio (β / α) of the content β (% by mass) of the specific anion-containing compound to the content α (% by mass) of the compound represented by the formula (1) in the non-aqueous electrolyte is 20.

[0229] [Example 2] In Example 1, LiPF 6 was 13.67% by mass, EC was 29.77% by mass, EMC was 53.48% by mass, VC was 1.98% by mass, Compound 1-1 was 0.10% by mass, and LiPO 2 F 2 was 1.0% by mass. A non-aqueous electrolyte was prepared in the same manner as in Example 1 except for the above. The ratio (β / α) of the content β (% by mass) of the specific anion-containing compound to the content α (% by mass) of the compound represented by the formula (1) in the non-aqueous electrolyte is 10.

[0230] [Example 3] In Example 1, LiPF 6 was 13.66% by mass, EC was 29.74% by mass, EMC was 53.42% by mass, VC was 1.98% by mass, Compound 1-1 was 0.20% by mass, and LiPO 2 F 2 was 1.0% by mass. A non-aqueous electrolyte was prepared in the same manner as in Example 1 except for the above. The ratio (β / α) of the content β (% by mass) of the specific anion-containing compound to the content α (% by mass) of the compound represented by the formula (1) in the non-aqueous electrolyte is 5.

[0231] [Example 4] In Example 1, LiPF 6 was 13.62% by mass, EC was 29.65% by mass, EMC was 53.26% by mass, VC was 1.97% by mass, Compound 1-1 was 0.50% by mass, and LiPO 2 F 2 was 1.0% by mass. A non-aqueous electrolyte was prepared in the same manner as in Example 1 except for the above. The ratio (β / α) of the content β (% by mass) of the specific anion-containing compound to the content α (% by mass) of the compound represented by the formula (1) in the non-aqueous electrolyte is 2.

[0232] [Example 5] In Example 1, except that LiPF 6 was 13.55% by mass, EC was 29.50% by mass, EMC was 52.99% by mass, VC was 1.96% by mass, Compound 1-1 was 1.0% by mass, and LiPO 2 F 2 was 1.0% by mass, a non-aqueous electrolyte was prepared in the same manner as in Example 1. The ratio (β / α) of the content β (mass%) of the specific anion-containing compound to the content α (mass%) of the compound represented by formula (1) in the non-aqueous electrolyte is 1.

[0233] [Example 6] In Example 1, except that LiPO 2 F 2 was not included and LiFSO 3 was 1.0% by mass, a non-aqueous electrolyte was prepared in the same manner as in Example 1. The ratio (β / α) of the content β (mass%) of the specific anion-containing compound to the content α (mass%) of the compound represented by formula (1) in the non-aqueous electrolyte is 20.

[0234] [Example 7] In Example 2, except that LiPO 2 F 2 was not included and LiFSO 3 was 1.0% by mass, a non-aqueous electrolyte was prepared in the same manner as in Example 2. The ratio (β / α) of the content β (mass%) of the specific anion-containing compound to the content α (mass%) of the compound represented by formula (1) in the non-aqueous electrolyte is 10.

[0235] [Example 8] In Example 3, except that LiPO 2 F 2 was not included and LiFSO 3 was 1.0% by mass, a non-aqueous electrolyte was prepared in the same manner as in Example 3. The ratio (β / α) of the content β (mass%) of the specific anion-containing compound to the content α (mass%) of the compound represented by formula (1) in the non-aqueous electrolyte is 5.

[0236] [Example 9] In Example 4, LiPO 2 F2 excluding LiFSO 3 A non-aqueous electrolyte solution was prepared in the same manner as in Example 4, except that the content of LiFSO was 1.0% by mass. The ratio (β / α) of the content β (% by mass) of the specific anion-containing compound to the content α (% by mass) of the compound represented by formula (1) in the non-aqueous electrolyte solution is 2.

[0237] [Example 10] In Example 5, excluding LiPO 2 F 2 excluding LiFSO 3 A non-aqueous electrolyte solution was prepared in the same manner as in Example 5, except that the content of LiFSO was 1.0% by mass. The ratio (β / α) of the content β (% by mass) of the specific anion-containing compound to the content α (% by mass) of the compound represented by formula (1) in the non-aqueous electrolyte solution is 1.

[0238] [Example 11] In Example 6, a non-aqueous electrolyte solution was prepared in the same manner as in Example 6, except that Compound 1-1 was not included and the content of Compound 1-2 was 0.050% by mass. The ratio (β / α) of the content β (% by mass) of the specific anion-containing compound to the content α (% by mass) of the compound represented by formula (1) in the non-aqueous electrolyte solution is 20.

[0239] [Example 12] In Example 7, a non-aqueous electrolyte solution was prepared in the same manner as in Example 7, except that Compound 1-1 was not included and the content of Compound 1-2 was 0.10% by mass. The ratio (β / α) of the content β (% by mass) of the specific anion-containing compound to the content α (% by mass) of the compound represented by formula (1) in the non-aqueous electrolyte solution is 10.

[0240] [Example 13] In Example 8, a non-aqueous electrolyte solution was prepared in the same manner as in Example 8, except that Compound 1-1 was not included and the content of Compound 1-2 was 0.20% by mass. The ratio (β / α) of the content β (% by mass) of the specific anion-containing compound to the content α (% by mass) of the compound represented by formula (1) in the non-aqueous electrolyte solution is 5.

[0241] [Example 14] In Example 9, a non-aqueous electrolyte was prepared in the same manner as in Example 9, except that Compound 1-1 was not included and Compound 1-2 was 0.50% by mass. The ratio (β / α) of the content β (% by mass) of a specific anion-containing compound to the content α (% by mass) of the compound represented by the formula (1) in the non-aqueous electrolyte is 2.

[0242] [Example 15] In Example 10, a non-aqueous electrolyte was prepared in the same manner as in Example 10, except that Compound 1-1 was not included and Compound 1-2 was 1.0% by mass. The ratio (β / α) of the content β (% by mass) of a specific anion-containing compound to the content α (% by mass) of the compound represented by the formula (1) in the non-aqueous electrolyte is 1.

[0243] [Comparative Example 1] In Example 1, a non-aqueous electrolyte was prepared in the same manner as in Example 1, except that Compound 1-1 and LiPO 2 F 2 were not included. In the non-aqueous electrolyte, 13.82% by mass of LiPF 6 , 30.11% by mass of EC, 54.07% by mass of EMC, and 2.00% by mass of VC are included.

[0244] [Comparative Example 2] In Example 1, a non-aqueous electrolyte was prepared in the same manner as in Example 1, except that Compound 1-1 was not included. In the non-aqueous electrolyte, 13.68% by mass of LiPF 6 , 29.80% by mass of EC, 53.53% by mass of EMC, 1.98% by mass of VC, and 1.0% by mass of LiPO 2 F 2 are included.

[0245] [Comparative Example 3] In Example 11, a non-aqueous electrolyte was prepared in the same manner as in Example 11, except that Compound 1-1 was not included. In the non-aqueous electrolyte, 13.68% by mass of LiPF 6 , 29.80% by mass of EC, 53.53% by mass of EMC, 1.98% by mass of VC, and 1.0% by mass of LiFSO 3 are included.

[0246] [Comparative Example 4] In Example 1, an non-aqueous electrolyte was prepared in the same manner as in Example 1 except that LiPO 2 F 2 was not included. In the non-aqueous electrolyte, LiPF 6 is contained at 13.82% by mass, EC at 30.09% by mass, EMC at 54.04% by mass, VC at 2.00% by mass, and Compound 1-1 at 0.050% by mass.

[0247] [Comparative Example 5] In Example 2, an non-aqueous electrolyte was prepared in the same manner as in Example 2 except that LiPO 2 F 2 was not included. In the non-aqueous electrolyte, LiPF 6 is contained at 13.81% by mass, EC at 30.07% by mass, EMC at 54.02% by mass, VC at 2.00% by mass, and Compound 1-1 at 0.10% by mass.

[0248] [Comparative Example 6] In Example 3, an non-aqueous electrolyte was prepared in the same manner as in Example 3 except that LiPO 2 F 2 was not included. In the non-aqueous electrolyte, LiPF 6 is contained at 13.80% by mass, EC at 30.04% by mass, EMC at 53.96% by mass, VC at 2.00% by mass, and Compound 1-1 at 0.20% by mass.

[0249] [Comparative Example 7] In Example 4, an non-aqueous electrolyte was prepared in the same manner as in Example 4 except that LiPO 2 F 2 was not included. In the non-aqueous electrolyte, LiPF 6 is contained at 13.75% by mass, EC at 29.95% by mass, EMC at 53.80% by mass, VC at 1.99% by mass, and Compound 1-1 at 0.50% by mass.

[0250] [Comparative Example 8] In Example 5, an non-aqueous electrolyte was prepared in the same manner as in Example 5 except that LiPO 2 F 2A non-aqueous electrolyte was prepared in the same manner as in Example 5, except that it did not contain 6 LiPF was 13.68% by mass, EC was 29.80% by mass, EMC was 53.53% by mass, VC was 1.98% by mass, and Compound 1-1 was 1.0% by mass.

[0251] [Comparative Example 9] In Example 6, a non-aqueous electrolyte was prepared in the same manner as in Example 6, except that it did not contain LiPO 2 F 2 LiPF was 13.82% by mass, EC was 30.09% by mass, EMC was 54.04% by mass, VC was 2.00% by mass, and Compound 1-2 was 0.050% by mass. 6 was contained in the non-aqueous electrolyte.

[0252] [Comparative Example 10] In Example 7, a non-aqueous electrolyte was prepared in the same manner as in Example 7, except that it did not contain LiPO 2 F 2 LiPF was 13.81% by mass, EC was 30.07% by mass, EMC was 54.02% by mass, VC was 2.00% by mass, and Compound 1-2 was 0.10% by mass. 6 was contained in this non-aqueous electrolyte.

[0253] [Comparative Example 11] In Example 8, a non-aqueous electrolyte was prepared in the same manner as in Example 8, except that it did not contain LiPO 2 F 2 LiPF was 13.80% by mass, EC was 30.04% by mass, EMC was 53.96% by mass, VC was 2.00% by mass, and Compound 1-2 was 0.20% by mass. 6 was contained in the non-aqueous electrolyte.

[0254] [Comparative Example 12] In Example 9, a non-aqueous electrolyte was prepared in the same manner as in Example 9, except that it did not contain LiPO 2 F 2 LiPF was 13.80% by mass, EC was 30.04% by mass, EMC was 53.96% by mass, VC was 2.00% by mass, and Compound 1-2 was 0.20% by mass. 6It contains 13.75% by mass of [substance name 1], 29.95% by mass of EC, 53.80% by mass of EMC, 1.99% by mass of VC, and 0.50% by mass of Compound 1-2.

[0255] [Comparative Example 13] In Example 10, a non-aqueous electrolyte was prepared in the same manner as in Example 10 except that LiPO 2 F 2 was not included. In the non-aqueous electrolyte, it contains 13.68% by mass of LiPF 6 , 29.80% by mass of EC, 53.53% by mass of EMC, 1.98% by mass of VC, and 1.0% by mass of Compound 1-2.

[0256] [Fabrication of Non-aqueous Electrolyte Secondary Battery] [Fabrication of Positive Electrode] As a positive electrode active material, 90% by mass of Li(Ni 0.5 Mn 0.3 Co 0.2 )O 2 (LNMC), 7% by mass of acetylene black as a conductive material, and 3% by mass of polyvinylidene fluoride (PVdF) as a binder were mixed in an N-methylpyrrolidone solvent to form a slurry. The obtained slurry was applied to both sides of a 15-μm-thick aluminum foil serving as a current collector, dried, and pressed to obtain a positive electrode.

[0257] [Fabrication of Negative Electrode] As a negative electrode active material, natural graphite powder, an aqueous dispersion of sodium carboxymethyl cellulose (sodium carboxymethyl cellulose concentration 1% by mass) as a thickener, and an aqueous dispersion of styrene-butadiene rubber (styrene-butadiene rubber concentration 50% by mass) as a binder were added and mixed with a disperser to form a slurry. The obtained slurry was applied to one side of a 10-μm-thick copper foil serving as a current collector, dried, and pressed to obtain a negative electrode. In the negative electrode after drying, it was prepared so that the mass ratio of natural graphite:sodium carboxymethyl cellulose:styrene-butadiene rubber was 98:1:1.

[0258] [Manufacture of Non-aqueous Electrolyte Battery] The above-described positive electrode, negative electrode, and polyolefin separator were laminated in the order of negative electrode, separator, positive electrode, separator, and negative electrode. The thus obtained battery element was wrapped with an aluminum laminate film, and after injecting each non-aqueous electrolyte of Examples 1 to 15 and Comparative Examples 1 to 13, it was vacuum-sealed to produce a sheet-like non-aqueous electrolyte secondary battery (lithium secondary battery).

[0259] <Evaluation of Non-aqueous Electrolyte Secondary Battery> [Initial Discharge] With each lithium secondary battery obtained above sandwiched between glass plates and under pressure, at 25°C, it was charged at a constant current corresponding to 0.05C for 20 hours, and then discharged at a constant current of 0.2C until 2.7V. Further, after charging at a constant current - constant voltage up to 4.2V (also referred to as "CC - CV charging") at a current corresponding to 0.2C (0.05C cut), it was discharged at a constant current of 0.2C until 2.7V. Next, after charging at CC - CV up to 4.2V at 0.2C (0.05C cut), it was discharged again at 0.2C until 2.7V to perform the initial discharge. Thereby, the battery characteristics were stabilized. Here, 1C represents the current value for discharging the reference capacity of the battery in 1 hour. For example, 0.2C represents a value that is 1 / 5 of the current value at 1C. The same applies hereinafter.

[0260] [High-temperature Storage Test] As described above, the lithium secondary battery that had undergone initial charge and discharge was charged at CC - CV up to 4.2V at 0.2C (0.05C cut) at 25°C, and then subjected to high-temperature storage under the conditions of 60°C for 2 weeks. Next, at 25°C, it was discharged at a constant current of 0.2C until 2.7V. Thereafter, at 25°C, after charging at CC - CV up to 4.2V, it was discharged again at 0.2C until 2.7V, and further, at 25°C, after charging at CC - CV up to 3.75V at 0.2C (0.05C cut). Thereafter, at 25°C, charging currents of 25 mA, 50 mA, and 100 mA were passed for 2 seconds each, and the slope when plotting the voltage change at each current value on the vertical axis and the current value on the horizontal axis was taken as the direct current resistance after storage (DCR). Table 1 shows the relative values of the DCR after storage in a lithium secondary battery fabricated using the non-aqueous electrolyte of Comparative Example 1 prepared as described above, with the DCR after storage in Comparative Example 1 taken as 100.0%.

[0261]

Table 1

[0262] From Table 1, when using the non-aqueous electrolyte according to this embodiment, the DCR after storage was improved compared to the non-aqueous electrolyte (Comparative Example 1) in which neither the compound represented by formula (1) nor the specific anion-containing compound was added. Regarding Compound 1-1 as the compound represented by formula (1) and LiPO 2 F 2 as the specific anion-containing compound, the non-aqueous electrolytes of Examples 1 to 5 in which both were used had an improved DCR after storage compared to Comparative Examples 4 to 8 in which Compound 1-1 was used alone without using the specific anion-containing compound, or Comparative Example 2 in which LiPO 2 F 2 was used alone without using Compound 1-1. Similarly, regarding Compound 1-1 as the compound represented by formula (1) and LiFSO 3 as the specific anion-containing compound, the non-aqueous electrolytes of Examples 6 to 10 in which both were used had an improved DCR after storage compared to Comparative Examples 4 to 8 in which Compound 1-1 was used alone without using the specific anion-containing compound, or Comparative Example 3 in which LiFSO 3 was used alone without using Compound 1-1.

[0263] Further, when using the non-aqueous electrolyte of Examples 11 to 15 in which Compound 1-2 was used as the compound represented by formula (1) and LiFSO 3 was used as the specific anion-containing compound, the DCR after storage was improved compared to Comparative Examples 9 to 13 in which Compound 1-2 was used alone without using the specific anion-containing compound, or Comparative Example 3 in which LiFSO 3 was used alone without using Compound 1-2.

[0264] From the above, by using a non-aqueous electrolyte containing both the compound represented by the formula (1) and a specific anion-containing compound, the Li + conductivity of the interfacial protective film on the electrode is improved, and as a result, it has been shown that the DCR after storage is improved.

Claims

1. A non-aqueous electrolyte containing a non-aqueous solvent and an electrolyte, wherein the non-aqueous electrolyte further contains a compound represented by the following formula (1), the electrolyte contains at least one specific anion-containing compound selected from the group consisting of an anion-containing compound having a P=O bond and a P-F bond and an anion-containing compound having an S=O bond and an S-X bond, and X in the S-X bond is a heteroatom, the non-aqueous electrolyte. 【Chemical 1】 (In formula (1), R is a hydrocarbon group having 5 to 10 carbon atoms.)

2. The non-aqueous electrolyte according to claim 1, wherein R in the formula (1) is a hydrocarbon group having 5 to 8 carbon atoms.

3. The non-aqueous electrolyte according to claim 1, wherein R in the formula (1) is an alkyl group.

4. The non-aqueous electrolyte according to claim 1, wherein the content of the compound represented by the formula (1) in the non-aqueous electrolyte is 0.05% by mass or more and 1% by mass or less.

5. When the content of the compound represented by the formula (1) in the non-aqueous electrolyte is α% by mass and the content of the specific anion-containing compound is β% by mass, the content ratio represented by β / α is 0.01 or more and 100, the non-aqueous electrolyte according to any one of claims 1 to 4.

6. The non-aqueous electrolyte according to claim 5, wherein the content ratio represented by β / α is 0.5 or more and 35 or less.

7. An energy device including a negative electrode, a positive electrode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte contains a non-aqueous solvent, an electrolyte, and a compound represented by the following formula (1), the electrolyte contains at least one specific anion-containing compound selected from the group consisting of an anion-containing compound having a P=O bond and a P-F bond and an anion-containing compound having an S=O bond and an S-X bond, and X in the S-X bond is a heteroatom, the energy device. [Chemical Formula 2] (In formula (1), R is a hydrocarbon group having 5 to 10 carbon atoms.)

8. The negative electrode includes a current collector and a negative electrode active material layer formed on the current collector, the negative electrode active material layer contains at least one selected from the group consisting of silicon, simple metals, alloys and compounds, tin, simple metals, alloys and compounds, carbon-based materials, and lithium titanium composite oxides, the energy device according to claim 7.

9. The positive electrode includes a current collector and a positive electrode active material layer formed on the current collector, The energy device according to claim 7, wherein the positive electrode active material layer contains at least one selected from the group consisting of lithium cobalt composite oxide, lithium cobalt nickel composite oxide, lithium manganese composite oxide, lithium cobalt manganese composite oxide, lithium nickel composite oxide, lithium nickel manganese composite oxide, and lithium cobalt nickel manganese composite oxide.

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