Non-aqueous electrolyte secondary battery, method for producing non-aqueous electrolyte secondary battery, and vehicle

Abstract

The present invention relates to a non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte contains an anion represented by general formula (1), and the separator is provided with a base material layer and a coating layer, said coating layer having a total thickness of 1.0-10.0μm.

Description

Non-aqueous electrolyte secondary battery, method for manufacturing a non-aqueous electrolyte secondary battery, and vehicle

[0001] This invention relates to a non-aqueous electrolyte secondary battery, a method for manufacturing a non-aqueous electrolyte secondary battery, and a vehicle.

[0002] Lithium-ion secondary batteries, among others, are widely used in applications such as power supplies for small devices like mobile phones and laptops, and power supplies for vehicles like electric cars. Therefore, numerous studies have been conducted on various battery components, including the positive electrode, negative electrode, separator, and electrolyte, as means of improving battery characteristics.

[0003] In the case of electrolytes, numerous studies have been conducted on the components of the electrolyte, such as additives, electrolytes, and solvents, with the aim of improving battery characteristics. For example, Patent Document 1 discloses that by including a specific imide salt compound in a non-aqueous electrolyte, the increase in internal resistance and gas generation after high-temperature cycling of the battery can be suppressed. Furthermore, Patent Document 2 discloses that by using an electrolyte containing an electrolyte salt containing a specific imide anion in a secondary battery equipped with a heat-resistant layer and a separator, the high-temperature cycle retention rate, high-temperature charge storage retention rate, and low-temperature load retention rate can be improved.

[0004] International Publication No. 2017 / 111143, International Publication No. 2023 / 120687

[0005] In recent years, the demand for higher performance in secondary batteries has been increasing, and there is a need to achieve high levels of battery capacity. One way to increase the capacity of secondary batteries is to pack as much electrode active material as possible into a limited battery volume. Specifically, this includes methods such as increasing the density of the electrode active material layer and reducing the volume occupied by materials other than the active material inside the battery.

[0006] However, reducing the internal voids of a battery to increase its capacity can lead to a significant increase in internal pressure if even a small amount of gas is generated due to the decomposition of the electrolyte. In particular, the non-aqueous solvent in a non-aqueous electrolyte undergoes localized oxidative decomposition at the interface between the positive electrode material and the non-aqueous electrolyte during the charging state. The resulting decomposition products and gases inhibit the desirable electrochemical reactions of the battery, leading to a decrease in its electrochemical properties.

[0007] While the non-aqueous electrolyte disclosed in Patent Document 1 is shown to be effective in preventing gas generation after high-temperature cycling, it does not disclose gas generation after high-temperature charging and storage. Similarly, while the secondary battery disclosed in Patent Document 2 discloses high-temperature cycling retention rate, high-temperature charging and storage retention rate, and low-temperature load retention rate, it does not disclose gas generation after high-temperature charging and storage. In contrast, in an environment where a secondary battery is charged and stored at high temperatures, the state of high positive electrode potential and low negative electrode potential persists for a longer period than during high-temperature cycling. Therefore, the load on the non-aqueous electrolyte in contact with these electrodes increases, making it more susceptible to decomposition and gas generation.

[0008] This invention has been made in view of the above problems, and the object of this invention is to provide a non-aqueous electrolyte secondary battery that is excellent in suppressing gas generation during high-temperature charging and storage. Furthermore, the object of this invention is to provide a method for manufacturing a non-aqueous electrolyte secondary battery that is excellent in suppressing gas generation during high-temperature charging and storage. Moreover, the object of this invention is to provide a vehicle that includes a non-aqueous electrolyte secondary battery that is excellent in suppressing gas generation during high-temperature charging and storage.

[0009] As a result of diligent research to solve the above problems, the present inventors have found that by incorporating an anion represented by general formula (1) having a specific structure into a non-aqueous electrolyte, a non-aqueous electrolyte secondary battery having a separator comprising a base layer and a coating layer with a total thickness of 1.0 to 10.0 μm exhibits excellent gas generation suppression during high-temperature charging and storage, thus completing the present invention.

[0010] In other words, the gist of the present invention is as follows: [1] A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte contains an anion represented by the following general formula (1), and the separator comprises a base layer and a coating layer, the total thickness of the coating layer being 1.0 to 10.0 μm.

[0011]

[0012] (In general formula (1), X represents a sulfur atom or a phosphorus atom, m is 1 or 2, and R １ ~R ４ Each of these independently represents a fluorine atom, a C1-C4 alkyl group, a C1-C4 halogenated alkyl group, or an -OH group. However, when X is a sulfur atom, m is 2 and R ４ (It does not exist, and if X is a phosphorus atom, then m is 1.)

[0013] [2] As an anion represented by the general formula (1), R in the general formula (1) １ ~R ４ However, each is independently an anion which is a fluorine atom or a trifluoromethyl group, or R in the general formula (1) above. １ ~R ３ However, each is independently a fluorine atom or a trifluoromethyl group, and R ４[1] A non-aqueous electrolyte secondary battery according to [1], comprising an anion in which no is present. [3] A non-aqueous electrolyte secondary battery according to [1] or [2], wherein the anion represented by the general formula (1) is a sulfur atom in the general formula (1). [4] A non-aqueous electrolyte secondary battery according to any one of [1] to [3], comprising at least one selected from bis(difluorophosphoryl)imide anion, (difluorophosphoryl)(trifluoromethanesulfonyl)imide anion, and (difluorophosphoryl)(fluorosulfonyl)imide anion, wherein the anion represented by the general formula (1). [5] A non-aqueous electrolyte secondary battery according to any one of [1] to [4], comprising (difluorophosphoryl)(fluorosulfonyl)imide anion, wherein the anion represented by the general formula (1). [6] A non-aqueous electrolyte secondary battery according to any one of [1] to [5], wherein the content of the anion represented by the general formula (1) in the non-aqueous electrolyte is 0.001 to 10% by mass. [7] A non-aqueous electrolyte secondary battery according to any one of [1] to [6], wherein the non-aqueous electrolyte substantially does not contain succinic anhydride. [8] A non-aqueous electrolyte secondary battery according to any one of [1] to [7], wherein the total thickness of the coating layer is 1.2 to 6.5 μm. [9] A non-aqueous electrolyte secondary battery according to any one of [1] to [8], wherein the ratio of the total thickness of the coating layer to the thickness of the substrate layer {total thickness of the coating layer (μm) / thickness of the substrate layer (μm)} is 0.10 to 0.90.

[10] The non-aqueous electrolyte secondary battery according to any one of [1] to [9], wherein the separator comprises the coating layer at least on the positive electrode side, and the ratio of the thickness of the coating layer on the positive electrode side to the thickness of the substrate layer {thickness of the coating layer on the positive electrode side (μm) / thickness of the substrate layer (μm)} is 0.10 to 0.70.

[11] A method for manufacturing a non-aqueous electrolyte secondary battery according to any one of [1] to

[10] , wherein the coating layer comprises at least one selected from the group consisting of inorganic particles and polymer materials.

[12] The non-aqueous electrolyte secondary battery according to

[11] , wherein the coating layer further comprises a binder.

[13] The manufacturing method of the non-aqueous electrolyte secondary battery according to any one of [1] to

[12] above, wherein as the separator, one having a base material layer and a coat layer is used, and a step of dissolving a compound containing an anion represented by the general formula (1) as a constituent anion in a non-aqueous solvent is included, the manufacturing method of the non-aqueous electrolyte secondary battery.

[14] A vehicle including the non-aqueous electrolyte secondary battery according to any one of [1] to

[12] above.

[0014] The non-aqueous electrolyte secondary battery according to this embodiment is excellent in the effect of suppressing gas generation during high-temperature charge and storage. Further, by the manufacturing method of the non-aqueous electrolyte secondary battery according to this embodiment, a non-aqueous electrolyte secondary battery excellent in the effect of suppressing gas generation during high-temperature charge and storage can be obtained. Furthermore, the vehicle according to this embodiment is excellent in the effect of suppressing gas generation during high-temperature charge and storage of the non-aqueous electrolyte secondary battery.

[0015] Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the descriptions given below are examples of embodiments of the present invention, and the present invention is not limited to these contents. Further, the present invention can be arbitrarily modified and implemented within the scope not departing from its gist. In this specification, "~" is used in the meaning of including the numerical values described before and after it as the lower limit value and the upper limit value.

[0016] [1. Non-aqueous electrolyte secondary battery] The non-aqueous electrolyte secondary battery according to this embodiment includes a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte. The above non-aqueous electrolyte contains an anion represented by the following general formula (1). Further, the above separator includes a base material layer and a coat layer, and the total thickness of the coat layer is 1.0 to 10.0 μm.

[0017]

[0018] (In the general formula (1), X represents a sulfur atom or a phosphorus atom, m is 1 or 2, and R １ ~ R ４ each independently represents a fluorine atom, an alkyl group having 1 to 4 carbon atoms, a halogenated alkyl group having 1 to 4 carbon atoms, or an -OH group. However, when X is a sulfur atom, m is 2 and R ４ does not exist, and when X is a phosphorus atom, m is 1.)

[0019] The non-aqueous electrolyte secondary battery according to this embodiment exhibits excellent gas generation suppression during high-temperature charging and storage. The inventors believe the reason for this is as follows. However, the present invention is not limited to what is described below.

[0020] The separator used in the non-aqueous electrolyte secondary battery according to this embodiment comprises a base layer and a coating layer. Generally, the coating layer is made of inorganic particles held by a binder or a polymer material, and is provided for the purpose of improving heat resistance and suppressing the meltdown of the separator. Of these, when a separator having a coating layer made of inorganic particles held by a binder is charged and stored at high temperatures, it is conceivable that, although slight, the binder constituting the coating layer may dissolve, causing the binder itself or the inorganic particles to reach the positive electrode, and potentially causing the decomposition of the non-aqueous electrolyte through catalytic action. In the case of a separator using a polymer material for the coating layer, it is conceivable that, although slight, oxidation of the polymer material may cause subsequent decomposition of the non-aqueous electrolyte. In contrast, when using the non-aqueous electrolyte according to this embodiment, it is thought that the presence of anions represented by general formula (1) prevents interaction between the binder or inorganic particles and the positive electrode, or suppresses slight oxidation of the polymer material, thereby suppressing the decomposition of the non-aqueous electrolyte.

[0021] [1. Non-aqueous electrolyte] [1-1. Anion represented by general formula (1)] The non-aqueous electrolyte according to this embodiment contains the anion represented by the following general formula (1).

[0022]

[0023] (In general formula (1), X represents a sulfur atom or a phosphorus atom, m is 1 or 2, and R １ ~R ４ Each of these independently represents a fluorine atom, a C1-C4 alkyl group, a C1-C4 halogenated alkyl group, or an -OH group. However, when X is a sulfur atom, m is 2 and R ４ (It does not exist, and if X is a phosphorus atom, then m is 1.)

[0024] [R １ ~R４ ] R in general formula (1) １ ~R ４ Each of these independently represents a fluorine atom, a C1-C4 alkyl group, a C1-C4 halogenated alkyl group, or a hydroxyl group (-OH group). Specifically, R １ ~R ４ Each of these can independently be a fluorine atom, a linear alkyl group such as a methyl group, an ethyl group, an n-propyl group or an n-butyl group, a fluoromethyl group, a trifluoromethyl group, a halogenated alkyl group such as a 2-fluoroethyl group, a 2,2-difluoroethyl group, a 2,2,2-trifluoroethyl group, a 3-fluoropropyl group, a 3,3-difluoropropyl group, a 3,3,3-trifluoropropyl group, a 2,2,3,3-tetrafluoropropyl group, a 2,2,3,3,3-pentafluoropropyl group, a 4-fluorobutyl group or a 4,4-difluorobutyl group, or an -OH group, among which a fluorine atom, a methyl group, an ethyl group or a trifluoromethyl group is more preferred, a fluorine atom or a trifluoroethyl group is even more preferred, and a fluorine atom is even more preferred. １ ~R ４ It is especially preferable that all of them are fluorine atoms or trifluoromethyl groups, and it is particularly preferable that all of them are fluorine atoms. Here, if X is a sulfur atom, then R ４ Since it does not exist, in that case, R １ ~R ３ It is even more preferable that all of them are fluorine atoms or trifluoromethyl groups, and it is particularly preferable that all of them are fluorine atoms. That is, the electrolyte according to this embodiment has an anion represented by general formula (1), and R in the above general formula (1) １ ~R ３ However, each is independently a fluorine atom or a trifluoromethyl group, and R ４ It is particularly preferable that the anion contains a fluorine atom, a trifluoromethyl group, or is absent.

[0025] [X] In general formula (1), X represents a sulfur atom or a phosphorus atom, and is preferably a sulfur atom. When X is a sulfur atom, m is 2, and R ４It does not exist. Also, if X is a phosphorus atom, then m is 1.

[0026] In this embodiment, suitable countercations for the anion represented by general formula (1) include alkali metal cations, alkaline earth metal cations, ammonium cations, and phosphonium cations, among which alkali metal cations and alkaline earth metal cations are more preferred, and alkali metal cations are even more preferred.

[0027] A specific example of an alkali metal cation is lithium cation (Li ＋ ), sodium cation (Na ＋ ), potassium cation (K ＋ ), cesium cation (Cs ＋ ) are preferred examples. A specific example of an alkaline earth metal cation is magnesium cation (Mg ２＋ ), calcium cation (Ca ２＋ ) are preferred examples.

[0028] Among these, lithium cations, sodium cations, cesium cations, and magnesium cations are more preferred, and the more preferred countercation varies depending on the battery in which the electrolyte according to this embodiment is used. For example, when the electrolyte according to this embodiment is used in a lithium-ion battery, lithium cations are more preferred as the countercation, and when it is used in a sodium-ion battery, sodium cations are more preferred.

[0029] Specific examples of anions represented by general formula (1) are shown below, but the anions are not limited to these.

[0030] [When X is a sulfur atom]

[0031]

[0032] [When X is a phosphorus atom]

[0033]

[0034] Among the above anions, the anions represented by a-1 to a-7, a-10 to a-14, b-1, b-2, and b-7 to b-10 are preferred, the anions represented by a-1, a-2, a-6, a-7, a-10 to a-12, a-14, b-1, b-2, and b-7 to b-9 are more preferred, a-1 ((difluorophosphoryl)(fluorosulfonyl)imide anion), a-7 ((difluorophosphoryl)(trifluoromethanesulfonyl)imide anion), and b-1 (bis(difluorophosphoryl)imide anion) are even more preferred, a-1 ((difluorophosphoryl)(fluorosulfonyl)imide anion) and b-1 (bis(difluorophosphoryl)imide anion) are particularly preferred, and a-1 ((difluorophosphoryl)(fluorosulfonyl)imide anion) is the most preferred. This is because the coating is rich in fluoride ions, and R in general formula (1) １ R ２ P(=O)NX(=O) ｍ R ３ R ４ This is because, depending on the location, it prevents interaction between the binder and inorganic particles contained in the coating layer that makes up the separator and the positive electrode, and also suppresses slight oxidation of polymer materials, thereby inhibiting the decomposition of the non-aqueous electrolyte.

[0035] [Content] In the non-aqueous electrolyte according to this embodiment, the content of the anion represented by general formula (1) is preferably 0.001 to 10% by mass. Here, from the viewpoint of continuously preventing interaction between the binder or inorganic particles and the positive electrode, or sufficiently suppressing slight oxidation of the polymer material, and thereby suitably suppressing the decomposition of the non-aqueous electrolyte, the above content is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, even more preferably 0.5% by mass or more, and particularly preferably 0.8% by mass or more. Furthermore, from the viewpoint of quickly preventing interaction between the binder or inorganic particles and the positive electrode, or quickly suppressing slight oxidation of the polymer material, the above content is usually 10% by mass or less, preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and even more preferably 1.5% by mass or less. When the electrolyte according to this embodiment contains two or more anions represented by general formula (1), it is preferable that the total content of them satisfies the above range.

[0036] There are no particular restrictions on the method for incorporating the anion represented by general formula (1) into the electrolyte according to this embodiment. However, methods such as adding a compound in which the anion represented by general formula (1) and a countercation are paired (hereinafter sometimes simply referred to as "compound (1)") to a non-aqueous solvent, or adding a raw material for the anion represented by general formula (1) to a non-aqueous solvent to generate the anion represented by general formula (1) are also preferred. The anion represented by general formula (1) is sometimes referred to as an additive. The identification and measurement of the content of the anion represented by general formula (1) are performed by nuclear magnetic resonance (NMR) spectroscopy, ion chromatography-mass spectrometry (IC / MS), etc.

[0037] Furthermore, the R of the anion represented by general formula (1) １ ~R ４ If the substituent or atom is anything other than an -OH group, it becomes a structure that is highly susceptible to hydrolysis, and hydrolysis may proceed inside the battery, potentially leading to substitution with an -OH group.

[0038] Furthermore, the anion represented by general formula (1) in this embodiment can be used particularly suitably in non-aqueous electrolytes from the viewpoint of suppressing gas generation during high-temperature charging and storage, but it can also be suitably used as an insulating film coating agent from the viewpoint of forming an insulating film.

[0039] [1-2. Electrolyte] When the non-aqueous electrolyte in this embodiment contains an electrolyte, the electrolyte is not particularly limited as long as it can dissociate into cations and anions, even slightly, when dissolved in the non-aqueous solvent. A compound whose constituent anion is represented by general formula (1) may also be used as the electrolyte. From the viewpoint of increasing solubility, alkali metal salts are preferred as the electrolyte, lithium salts, sodium salts, and potassium salts are more preferred, and from the viewpoint of improving cycle characteristics, lithium salts are even more preferred. When the non-aqueous electrolyte secondary battery according to this embodiment is a lithium-ion battery, the counter cation of the electrolyte is preferably a lithium cation. When the non-aqueous electrolyte secondary battery according to this embodiment is a sodium-ion battery, the counter cation of the electrolyte is preferably a sodium cation. When the non-aqueous electrolyte secondary battery according to this embodiment is a potassium-ion battery, the counter cation of the electrolyte is preferably a potassium cation.

[0040] Examples of lithium salts include lithium fluoroborate, lithium fluorophosphate, lithium tungstate, lithium carboxylate, lithium sulfonate, lithium imide, lithium methide, lithium oxalate, and fluorine-containing organic lithium salts. A single lithium salt may be used, or two or more may be used in any ratio and combination.

[0041] Lithium salts are used as lithium fluoroborate salts (LiBF) from the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature charge / storage characteristics, and cycle characteristics. ４ ; LiPF as lithium fluorophosphate salt ６ Li ２ PO ３ F, LiPO ２ F ２ ; LiFSO as lithium sulfonate salt３ ,CH ３ SO ３ Li, CF ３ SO ３ Li; as 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-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide; LiC(FSO) as lithium methide salt ２ ) ３ LiC (CF ３ SO ２ ) ３ LiC(C ２ F ５ SO ２ ) ３ LiBF is preferred as the lithium oxalate salt, and is preferred to be lithium difluorooxalate borate, lithium bis(oxalate) borate, lithium tetrafluorooxalate phosphate, lithium difluorobis(oxalate) phosphate, or lithium tris(oxalate) phosphate, from the viewpoint of improving lower temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature charge / storage characteristics, and cycle characteristics. ４ LiPF ６ LiPO ２ F ２ , LiN (FSO ２ ) ２ Lithium bis(oxalate) borate, LiFSO ３ It is more preferable that LiPF is used, and furthermore, from the viewpoint of improving low-temperature output characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature charge / storage characteristics, and cycle characteristics. ６ It is even more preferable that this be the case.

[0042] Examples of combinations of two or more lithium salts include LiPF６ and LiN(FSO ２ ); ２ combination of; LiPF ６ and LiBF ４ combination of; LiPF ６ and LiN(CF ３ SO ２ ); ２ combination of; LiBF ４ and LiN(FSO ２ ); ２ combination of; LiBF ４ , LiPF ６ and LiN(FSO ２ ); ２ combination of etc. are exemplified. The combination of two or more lithium salts is, from the viewpoint of improving low-temperature output characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature charge storage characteristics, and cycle characteristics, the combination of LiPF ６ and LiN(FSO ２ ); ２ combination of; LiPF ６ and LiBF ４ combination of; LiBF ４ , LiPF ６ and LiN(FSO ２ ); ２ combination is preferred.

[0043] As the sodium salt, for example, sodium fluoroborate salts, sodium fluorophosphate salts, sodium tungstate salts, sodium carboxylate salts, sodium sulfonate salts, sodium imide salts, sodium methide salts, sodium oxalate salts, fluorine-containing organic sodium salts, etc. are exemplified. The sodium salt may be used alone or two or more may be used in any ratio and combination.

[0044] The sodium salt, from the viewpoint of improving low-temperature output characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature charge storage characteristics, and cycle characteristics, NaBF ４ as the sodium fluoroborate salt; NaPF ６ , Na ２ PO ３ F, NaPO ２F ２ ;NaFSO as sodium sulfonate salt ３ ,CH ３ SO ３ Na, CF ３ SO ３ Na; as sodium imide salt, NaN(FSO) ２ ) 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 sodium methide salt, NaC(FSO ２ ) ３ NaC(CF ３ SO ２ ) ３ NaC(C ２ F ５ SO ２ ) ３ ; Preferably, the sodium oxalate salt is sodium difluorooxalate borate, sodium bis(oxalate) borate, sodium tetrafluorooxalate phosphate, sodium difluorobis(oxalate) phosphate, or sodium tris(oxalate) phosphate, and from the viewpoint of improving lower temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature charge / storage characteristics, and cycle characteristics, NaBF ４ NaPF ６ NaPO ２ F ２ NaN(FSO) ２ ) ２ Sodium bis(oxalate) borate, NaFSO ３ It is more preferable that NaPF is used, and furthermore, from the viewpoint of improving low-temperature output characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature charge / storage characteristics, and cycle characteristics. ６ It is even more preferable that this be the case.

[0045] Examples of combinations of two or more sodium salts include NaPF ６ and NaN(FSO) ２ ) ２ The combination, NaPF ６ and NaBF ４ The combination, NaPF ６ and NaN(CF ３ SO ２ ) ２ The combination, NaBF ４ and NaN(FSO) ２ ) ２ The combination, NaBF ４ NaPF ６ and NaN(FSO) ２ ) ２ Combinations such as the following can be mentioned. Combinations of two or more sodium salts are considered to improve low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature charge / storage characteristics, and cycle characteristics, and NaPF ６ and NaN(FSO) ２ ) ２ The combination, NaPF ６ and NaBF ４ The combination, NaBF ４ NaPF ６ and NaN(FSO) ２ ) ２ A combination is preferable.

[0046] Examples of potassium salts include potassium fluoroborate, potassium fluorophosphate, potassium tungstate, potassium carboxylate, potassium sulfonate, potassium imide, potassium methide, potassium oxalate, and fluorine-containing organic potassium salts. Potassium salts may be used individually or in any ratio and combination of two or more types.

[0047] Potassium salts are used as potassium fluoroborate (KBF) from the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature charge / storage characteristics, and cycle characteristics. ４ ; as potassium fluorophosphate KPF ６ _K ２ PO３ F, KPO ２ F ２ ; as potassium sulfonate, KFSO ３ ,CH ３ SO ３ K, CF ３ SO ３ K; as potassium imide salt, KN (FSO ２ ) ２ , KN (FSO ２ ) (CF ３ SO ２ ), KN (CF ３ SO ２ ) ２ , KN (C ２ F ５ SO ２ ) ２ , potassium cyclic 1,2-perfluoroethanedisulfonylimide, potassium cyclic 1,3-perfluoropropanedisulfonylimide; potassium methide salt KC (FSO ２ ) ３ , KC (CF ３ SO ２ ) ３ , KC (C ２ F ５ SO ２ ) ３ ; Preferably, the potassium oxalate salt is potassium difluorooxalate borate, potassium bis(oxalate) borate, potassium tetrafluorooxalate phosphate, potassium difluorobis(oxalate) phosphate, or potassium tris(oxalate) phosphate, and from the viewpoint of improving lower temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature charge / storage characteristics, and cycle characteristics, KBF ４ KPF ６ , KPO ２ F ２ , KN (FSO ２ ) ２ Potassium bis(oxalate) borate, KFSO ３ It is more preferable that the KPF improves low-temperature output characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature charge / storage characteristics, and cycle characteristics. ６ It is even more preferable that this be the case.

[0048] Examples of combinations of two or more potassium salts include KPF ６ and KN (FSO) ２ ) ２ combination; KPF ６ and KBF ４ combination; KPF ６ and KN (CF ３ SO ２ ) ２ Combination; KBF ４ and KN (FSO) ２ ) ２ Combination; KBF ４ KPF ６ and KN (FSO) ２ ) ２ Combinations such as the following can be mentioned. Combinations of two or more potassium salts are considered to improve low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature charge / storage characteristics, and cycle characteristics, and KPF ６ and KN (FSO) ２ ) ２ combination; KPF ６ and KBF ４ Combination; KBF ４ KPF ６ and KN (FSO) ２ ) ２ A combination is preferable.

[0049] The electrolyte content in the non-aqueous electrolyte according to this embodiment is preferably 5 to 20% by mass. Here, from the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, the above content is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 9% by mass or more. Furthermore, from the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, the above content is preferably 20% by mass or less, more preferably 18% by mass or less, and even more preferably 16% by mass or less. Here, if two or more types of electrolytes are included, the above content refers to the total content of those electrolytes. In this specification, the identification of electrolytes and the electrolyte content are measured by nuclear magnetic resonance (NMR) analysis. If it is difficult to identify electrolytes or measure electrolyte content by nuclear magnetic resonance (NMR) analysis alone, other analyses such as infrared spectroscopy (IR) analysis and gas chromatography-mass spectrometry may be used in combination.

[0050] [1-3. Non-aqueous solvents] The non-aqueous solvent in this embodiment is not particularly limited as long as it is a non-aqueous solvent that dissolves the anion represented by general formula (1) and an optional electrolyte. From the viewpoint of suppressing oxidation-reduction decomposition in the battery, the non-aqueous solvent is preferably an organic solvent.

[0051] Examples of organic solvents include saturated cyclic carbonates, linear carbonates, linear carboxylic acid esters, cyclic carboxylic acid esters, ether compounds, and sulfone compounds. One organic solvent may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of suppressing oxidation-reduction decomposition in the battery, saturated cyclic carbonates, linear carbonates, linear carboxylic acid esters, cyclic carboxylic acid esters, ether compounds, and sulfone compounds are preferred organic solvents, and saturated cyclic carbonates, linear carbonates, and linear carboxylic acid esters are more preferred.

[0052] Examples of combinations of two or more organic solvents include a combination of saturated cyclic carbonate and linear carbonate, a combination of saturated cyclic carbonate and linear carboxylic acid ester, a combination of saturated cyclic carbonate and cyclic carboxylic acid ester, a combination of linear carbonate and linear carboxylic acid ester, and a combination of saturated cyclic carbonate, linear carbonate, and linear carboxylic acid ester. From the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, it is preferable that the combination of two or more organic solvents be a combination of saturated cyclic carbonate and linear carbonate, or a combination of saturated cyclic carbonate, linear carbonate, and linear carboxylic acid ester.

[0053] In this embodiment, the content of the non-aqueous solvent in the non-aqueous electrolyte is preferably 84 to 95% by mass. Here, from the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, the above content is preferably 84% by mass or more, more preferably 86% by mass or more, and even more preferably 88% by mass or more. Furthermore, from the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, the above content is preferably 95% by mass or less, more preferably 93% by mass or less, and even more preferably 91% by mass or less. Here, if two or more non-aqueous solvents are included, the above content refers to the total content of those solvents. In this specification, the identification of non-aqueous solvents and the content of non-aqueous solvents are measured by nuclear magnetic resonance (NMR) analysis. If it is difficult to identify non-aqueous solvents or measure the content of non-aqueous solvents by nuclear magnetic resonance (NMR) analysis alone, other analyses such as infrared spectroscopy (IR) analysis and gas chromatography-mass spectrometry may be used in combination.

[0054] [1-3-1. Saturated Cyclic Carbonates] Examples of saturated cyclic carbonates that serve as non-aqueous solvents in this embodiment include ethylene carbonate, propylene carbonate, butylene carbonate, and erythritol bis(carbonate). One type of saturated cyclic carbonate may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of improving the degree of alkali metal ion dissociation, ethylene carbonate and propylene carbonate are preferred, and ethylene carbonate is more preferred.

[0055] When saturated cyclic carbonate is used as the non-aqueous solvent, the content of saturated cyclic carbonate relative to the total non-aqueous solvent is preferably 3 to 90 volume percent. Here, from the viewpoint of suppressing the decrease in electrical conductivity due to the decrease in dielectric constant of the electrolyte and improving high-current discharge characteristics, stability to the negative electrode, cycle characteristics, oxidation-reduction resistance of the electrolyte, and high-temperature storage characteristics, the above content is preferably 3 volume percent or more, more preferably 5 volume percent or more, and even more preferably 10 volume percent or more. Furthermore, from the viewpoint of suppressing the decrease in electrical conductivity due to the decrease in dielectric constant of the electrolyte and improving high-current discharge characteristics, stability to the negative electrode, cycle characteristics, oxidation-reduction resistance of the electrolyte, and high-temperature storage characteristics, the above content is preferably 90 volume percent or less, more preferably 85 volume percent or less, and even more preferably 80 volume percent or less. Here, if two or more saturated cyclic carbonates are included, the above content refers to the total content of those two or more. In this specification, volume percent refers to the ratio of volume at 25°C and 1 atm.

[0056] [1-3-2. Chain-like carbonates] Examples of chain-like carbonates that serve as non-aqueous solvents in this embodiment include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propylisopropyl carbonate, ethyl methyl carbonate, methyl-n-propyl carbonate, methylphenyl carbonate, and methyl-2,2,2-trifluoroethyl carbonate. One type of chain-like carbonate may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of suppressing an increase in the viscosity of the electrolyte, chain-like carbonates having 3 to 5 carbon atoms are preferred, and dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are more preferred.

[0057] When a linear carbonate is used as the non-aqueous solvent, the content of the linear carbonate relative to the total non-aqueous solvent is preferably 15 to 90 volume percent. Here, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 15 volume percent or more, more preferably 20 volume percent or more, and even more preferably 25 volume percent or more. Furthermore, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 90 volume percent or less, more preferably 85 volume percent or less, and even more preferably 80 volume percent or less. Here, if two or more types of linear carbonates are included, the above content refers to the total content of those types.

[0058] In this embodiment, the non-aqueous solvent is preferably a combination of ethylene carbonate and a chain carbonate, and more preferably a combination of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate, from the viewpoint of suppressing the increase in viscosity of the electrolyte and improving electrical conductivity.

[0059] When ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate are used as non-aqueous solvents, the content of ethylene carbonate relative to the total non-aqueous solvent is preferably 15 to 45 volume percent. Here, from the viewpoint of improving the rate characteristics due to improved ion dissociation, the above content is preferably 15 volume percent or more, more preferably 20 volume percent or more, and even more preferably 30 volume percent or more. Furthermore, from the viewpoint of improving the rate characteristics due to improved ion dissociation, the above content is preferably 45 volume percent or less, and more preferably 40 volume percent or less.

[0060] When ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate are used as non-aqueous solvents, the content of dimethyl carbonate relative to the total non-aqueous solvent is preferably 20 to 50% by volume. From the viewpoint of suppressing an increase in the viscosity of the electrolyte, the above content is preferably 20% by volume or more, and more preferably 30% by volume or more. From the viewpoint of improving the low-temperature characteristics of the battery, the above content is preferably 50% by volume or less, and even more preferably 45% by volume or less.

[0061] When ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate are used as non-aqueous solvents, the content of ethyl methyl carbonate relative to the total non-aqueous solvent is preferably 20 to 50 volume percent. Here, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 20 volume percent or more, and more preferably 30 volume percent or more. Furthermore, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 50 volume percent or less, and even more preferably 45 volume percent or less.

[0062] [1-3-3. Chain-like Carboxylic Acid Esters] Examples of chain-like carboxylic acid esters that serve as non-aqueous solvents in this 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. One type of chain-like carboxylic acid ester may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate are preferred, and methyl acetate, ethyl acetate, and methyl propionate are more preferred.

[0063] The above-mentioned linear carboxylic acid ester may be a linear carboxylic acid ester in which some of the hydrogen atoms are replaced with fluorine atoms. Examples of fluorine-substituted linear carboxylic acid esters include methyl trifluoroacetate, ethyl trifluoroacetate, 2,2-difluoroethyl acetate, and 2,2,2-trifluoroethyl acetate. One type of fluorine-substituted linear carboxylic acid ester may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of suppressing the increase in viscosity of the electrolyte, methyl trifluoroacetate and ethyl trifluoroacetate are preferred as the fluorine-substituted linear carboxylic acid ester, and methyl trifluoroacetate is more preferred.

[0064] When a linear carboxylic acid ester is used as the non-aqueous solvent, the content of the linear carboxylic acid ester relative to the total non-aqueous solvent is preferably 1 to 70% by volume. Here, from the viewpoint of improving the electrical conductivity of the electrolyte and enhancing the high-current discharge characteristics of the battery, the above content is preferably 1% by volume or more, more preferably 5% by volume or more, and even more preferably 15% by volume or more. Furthermore, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, suppressing the decrease in electrical conductivity, suppressing the increase in negative electrode resistance, and ensuring that the high-current discharge characteristics of the battery are within a good range, the above content is preferably 70% by volume or less, more preferably 50% by volume or less, and even more preferably 40% by volume or less. Here, if two or more linear carboxylic acid esters are included, the above content refers to the total content of those esters.

[0065] [1-3-4. Cyclic Carboxylic Acid Esters] Examples of cyclic carboxylic acid esters that serve as non-aqueous solvents in this embodiment include γ-butyrolactone and γ-valerolactone. One type of cyclic carboxylic acid ester may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of improving electrical conductivity, γ-butyrolactone is preferred as the cyclic carboxylic acid ester.

[0066] The above-mentioned cyclic carboxylic acid ester may be a cyclic carboxylic acid ester in which some of the hydrogen atoms are replaced with fluorine atoms. Examples of fluorine-substituted cyclic carboxylic acid esters include 3-fluorotetrahydrofuran-2-one and 4-fluorotetrahydrofuran-2-one. A single fluorine-substituted cyclic carboxylic acid ester may be used, or two or more may be used in any ratio and combination. From the viewpoint of improving oxidation resistance, 3-fluorotetrahydrofuran-2-one is preferred as the fluorine-substituted cyclic carboxylic acid ester.

[0067] When a cyclic carboxylic acid ester is used as a non-aqueous solvent, the content of the cyclic carboxylic acid ester relative to the total non-aqueous solvent is preferably 1 to 70% by volume. Here, from the viewpoint of improving the electrical conductivity of the electrolyte and enhancing the high-current discharge characteristics of the battery, the above content is preferably 1% by volume or more, more preferably 5% by volume or more, and even more preferably 15% by volume or more. Furthermore, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, suppressing the decrease in electrical conductivity, suppressing the increase in negative electrode resistance, and ensuring that the high-current discharge characteristics of the battery are within a good range, the above content is preferably 70% by volume or less, more preferably 50% by volume or less, and even more preferably 40% by volume or less. Here, if two or more cyclic carboxylic acid esters are included, the above content refers to the total content of those esters.

[0068] [1-3-5. Ether Compounds] Examples of ether compounds that serve as non-aqueous solvents 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. The ether compound may be an ether compound in which some of the hydrogen atoms are substituted with fluorine atoms. The ether compound may be used alone, or two or more may be used in any ratio and combination.

[0069] From the viewpoint of suppressing the increase in viscosity of the electrolyte, the above ether compounds are preferably chain ethers having 3 to 10 carbon atoms and cyclic ethers having 3 to 6 carbon atoms. Of the chain ethers having 3 to 10 carbon atoms, dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are preferred from the viewpoint of having high solvation ability to lithium ions, improving ion dissociation, suppressing the increase in viscosity of the electrolyte, and improving ionic conductivity. Of the cyclic ethers having 3 to 6 carbon atoms, tetrahydrofuran, 1,3-dioxane, and 1,4-dioxane are preferred from the viewpoint of improving ionic conductivity.

[0070] When an ether compound is used as a non-aqueous solvent, the content of the ether compound relative to the total non-aqueous solvent is preferably 1 to 30 volume percent. Here, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 1 volume percent or more, more preferably 2 volume percent or more, and even more preferably 3 volume percent or more. Furthermore, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 30 volume percent or less, more preferably 25 volume percent or less, and even more preferably 20 volume percent or less. Here, if two or more ether compounds are included, the above content refers to the total content of those compounds.

[0071] [1-3-6. Sulfone Compounds] The sulfone compound that serves as the non-aqueous solvent in this embodiment may be a cyclic sulfone or a chain sulfone. One sulfone compound may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of improving ionic conductivity, the number of sulfonyl groups in the sulfone compound is preferably 1 to 2, and more preferably 1.

[0072] Examples of the above-mentioned cyclic sulfones include monosulfone compounds such as trimethylene sulfones, tetramethylene sulfones (sulfolanes), and hexamethylene sulfones; and disulfone compounds such as trimethylene disulfones, tetramethylene disulfones, and hexamethylene disulfones. A single cyclic sulfone may be used, or two or more may be used in any ratio and combination. From the viewpoint of suppressing the increase in viscosity of the electrolyte, cyclic sulfones having 3 to 6 carbon atoms are preferred, chain-like sulfones having 3 to 5 carbon atoms are more preferred, and sulfolanes are even more preferred.

[0073] Examples of sulfolanes include sulfolane; sulfolane derivatives such as 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,3-difluorosulfolane, 2-trifluoromethylsulfolane, and 3-trifluoromethylsulfolane. Sulfolanes may be used individually or in any ratio and combination of two or more. From the viewpoint of improving ionic conductivity, sulfolane and sulfolane derivatives are preferred, and sulfolane, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,3-difluorosulfolane, 2-trifluoromethylsulfolane, and 3-trifluoromethylsulfolane are more preferred.

[0074] From the viewpoint of improving oxidation resistance, sulfolane derivatives are preferably sulfolane derivatives in which one or more hydrogen atoms bonded to carbon atoms constituting the sulfolane ring are substituted with fluorine atoms, sulfolane derivatives in which one or more hydrogen atoms bonded to carbon atoms constituting the sulfolane ring are substituted with alkyl groups, and sulfolane derivatives in which one or more hydrogen atoms bonded to carbon atoms constituting the sulfolane ring are substituted with fluorine-substituted alkyl groups. More preferably are 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,3-difluorosulfolane, 2-trifluoromethylsulfolane, and 3-trifluoromethylsulfolane.

[0075] Examples of the above-mentioned chain-like sulfones include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, and pentafluoroethyl methyl sulfone. One type of chain-like sulfone may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of improving the high-temperature storage stability of the electrolyte, chain-like sulfones having 2 to 6 carbon atoms are preferred, chain-like sulfones having 2 to 5 carbon atoms are more preferred, and dimethyl sulfone, ethyl methyl sulfone, and monofluoromethyl methyl sulfone are even more preferred.

[0076] When a sulfone compound is used as a non-aqueous solvent, the content of the sulfone compound relative to the total non-aqueous solvent is preferably 0.3 to 40 volume percent. Here, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 0.3 volume percent or more, more preferably 0.5 volume percent or more, and even more preferably 1 volume percent or more. Furthermore, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 40 volume percent or less, more preferably 35 volume percent or less, and even more preferably 30 volume percent or less. Here, if two or more sulfone compounds are included, the above content refers to the total content of those compounds.

[0077] [1-4. Other Compounds] The non-aqueous electrolyte in this embodiment may contain other compounds besides the electrolyte, non-aqueous solvent, and the anion represented by general formula (1), to the extent that they do not significantly impair the effects of the present invention. The other compounds may be used individually or two or more in any ratio and combination. However, the non-aqueous electrolyte in this embodiment preferably contains substantially no succinic anhydride in order to efficiently prevent the interaction between the binder or inorganic particles used in the separator coating layer and the positive electrode, or to suppress slight oxidation of polymer materials. Substantially containing no succinic anhydride means that the content of succinic anhydride in the non-aqueous electrolyte is 0.001% by mass or less. The above content is preferably 0.0005% by mass or less, and more preferably 0.0001% by mass or less.

[0078] Other compounds include, for example, unsaturated cyclic carbonates having carbon-carbon unsaturated bonds and fluorine-containing cyclic carbonates. These other compounds may be used individually or in any ratio and combination of two or more. Unsaturated cyclic carbonates and fluorine-containing cyclic carbonates are preferred as other compounds from the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics.

[0079] The total content of other compounds in the non-aqueous electrolyte according to this embodiment is preferably 0.1 to 20% by mass. Here, from the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, the total content is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.5% by mass or more. Furthermore, from the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, the content is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. In this specification, the identification of other compounds and the content of other compounds are measured by nuclear magnetic resonance (NMR) analysis. If it is difficult to identify other compounds or measure the content of other compounds by nuclear magnetic resonance (NMR) analysis alone, other analyses such as infrared spectroscopy (IR) analysis and gas chromatography-mass spectrometry may be used in combination.

[0080] [1-4-1. Unsaturated Cyclic Carbonates] Examples of unsaturated cyclic carbonates that can be used as other compounds in this embodiment include vinylene carbonates; ethylene carbonates substituted with substituents having aromatic rings, carbon-carbon double bonds, or carbon-carbon triple bonds; phenyl carbonates; vinyl carbonates; allyl carbonates; catechol carbonates, etc. Unsaturated cyclic carbonates may be used individually or two or more in any ratio and combination. From the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, vinylene carbonates and ethylene carbonates substituted with substituents having aromatic rings, carbon-carbon double bonds, or carbon-carbon triple bonds are preferred, and vinylene carbonates are more preferred.

[0081] Examples of 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, and 4,5-diallyl vinylene carbonate. Vinylene carbonates may be used individually or in any ratio and combination of two or more types.

[0082] Examples of ethylene carbonates substituted with substituents having aromatic rings, carbon-carbon double bonds, or carbon-carbon triple bonds include vinylethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethynylethylene carbonate, 4-vinyl-5-ethynylethylene carbonate, 4-allyl-5-ethynylethylene carbonate, phenylethylene carbonate, 4,5-diphenylethylene carbonate, 4-phenyl-5-vinylethylene carbonate, 4-allyl-5-phenylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, and 4-methyl-5-allylethylene carbonate. Ethylene carbonates substituted with substituents having aromatic rings, carbon-carbon double bonds, or carbon-carbon triple bonds may be used individually or in any ratio and combination of two or more types.

[0083] From the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, vinylene carbonate, vinylethylene carbonate, and ethynylethylene carbonate are preferred as unsaturated cyclic carbonates, vinylene carbonate and vinylethylene carbonate are more preferred, and vinylene carbonate is even more preferred.

[0084] [1-4-2. Fluorine-containing cyclic carbonates] Other fluorine-containing cyclic carbonates that can be used as compounds in this embodiment include, for example, fluorinated cyclic carbonates having alkylene groups with 2 to 6 carbon atoms, such as fluorinated ethylene carbonate; and derivatives of fluorinated cyclic carbonates having alkylene groups with 2 to 6 carbon atoms, such as fluorinated ethylene carbonate substituted with alkyl groups with 1 to 4 carbon atoms. One type of fluorine-containing cyclic carbonate may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, fluoroethylene carbonates with 1 to 4 fluorine atoms, derivatives of fluoroethylene carbonates with 1 to 8 fluorine atoms, and ethylene carbonates having fluorine-containing groups are preferred as fluorine-containing cyclic carbonates.

[0085] Examples of fluoroethylene carbonates having 1 to 4 fluorine atoms, derivatives of fluoroethylene carbonates having 1 to 8 fluorine atoms, and ethylene carbonates 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, and 4,4-difluoro-5-methylethylene Examples include ethylene 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, etc. Fluoroethylene carbonates with 1 to 4 fluorine atoms, derivatives of fluoroethylene carbonates with 1 to 8 fluorine atoms, and ethylene carbonates having a fluorine-containing group may be used individually or in any ratio and combination of two or more types. Of the fluoroethylene carbonates having 1 to 4 fluorine atoms, derivatives of fluoroethylene carbonates having 1 to 8 fluorine atoms, and ethylene carbonates having a fluorine-containing group, monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate are preferred from the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics.

[0086] [1-5. Method for Producing Non-Aqueous Electrolyte] The method for producing a non-aqueous electrolyte in this embodiment includes a step of dissolving a compound containing an anion represented by general formula (1) as a constituent anion, and optionally an electrolyte and other compounds, in a non-aqueous solvent.

[0087] The same explanation as in [1-1. Anions represented by General Formula (1)] above applies to the anion represented by General Formula (1) in the method for producing a non-aqueous electrolyte in this embodiment, and the preferred embodiments are also the same.

[0088] The same description as in [1-2. Electrolytes] above applies to the electrolyte in the method for producing a non-aqueous electrolyte in this embodiment, and the preferred embodiments are also the same.

[0089] The same explanation as in [1-3. Non-aqueous solvents] above applies to the non-aqueous solvent in the method for producing the non-aqueous electrolyte in this embodiment, and the preferred embodiments are also the same.

[0090] For other compounds used in the method for producing the non-aqueous electrolyte in this embodiment, the same description as in [1-4. Other Compounds] above applies, and the preferred embodiments are also the same.

[0091] The method for dissolving compounds, electrolytes, and other compounds having an anion represented by general formula (1) as a constituent anion in a non-aqueous solvent is not particularly limited. The compounds, electrolytes, and other compounds may be prepared by sequentially dissolving each of them in a non-aqueous solvent. Alternatively, the compounds may be prepared by sequentially mixing each of the electrolytes and other compounds, which have an anion represented by general formula (1) as a constituent anion and are dissolved at high concentrations in a non-aqueous solvent, with the electrolyte and other compounds dissolved at high concentrations in a non-aqueous solvent, with the electrolyte and other compounds, which are non-aqueous solvent.

[0092] [2. Battery] The battery according to this embodiment includes a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte.

[0093] [2-1. Non-aqueous electrolyte] The non-aqueous electrolyte in this embodiment is described in the same way as the electrolyte described in [1. Non-aqueous electrolyte] above, and the preferred embodiment is also the same. The non-aqueous electrolyte may be used in combination with an electrolyte other than the non-aqueous electrolyte described above, as long as it does not significantly impair the effects of the present invention.

[0094] [2-2. Positive Electrode] In this embodiment, the positive electrode includes positive electrode active material in at least a portion of the surface of the current collector.

[0095] [2-2-1. Positive Electrode Active Material] The positive electrode active material in this embodiment is not particularly limited as long as it is capable of electrochemically intercalating and releasing metal ions. Examples of positive electrode active materials include lithium transition metal compounds, sodium transition metal compounds, potassium transition metal compounds, etc. The positive electrode active material may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of increasing the energy density of the battery, lithium transition metal compounds, sodium transition metal compounds, and potassium transition metal compounds are preferred as positive electrode active materials, and lithium transition metal compounds are more preferred.

[0096] [2-2-1-1. Lithium Transition Metal Compounds] The lithium transition metal compound that serves as the positive electrode active material in this embodiment is not particularly limited as long as it is a compound having a structure that allows for insertion, removal, and insertion of lithium ions. Examples of lithium transition metal compounds include lithium transition metal sulfides, lithium transition metal phosphate compounds, lithium transition metal silicate compounds, lithium transition metal borate compounds, and lithium transition metal composite oxides. One lithium transition metal compound may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of increasing the energy density of the battery, lithium transition metal phosphate compounds and lithium transition metal composite oxides are preferred, and lithium transition metal composite oxides are more preferred.

[0097] Examples of lithium transition metal composite oxide structures include spinel structures, olivine structures, and layered structures. From the viewpoint of battery capacity and durability, spinel structures, olivine structures, and layered structures are preferred for lithium transition metal composite oxides, and from the viewpoint of increasing battery capacity, layered structures are more preferred.

[0098] Lithium transition metal composite oxides having a spinel structure allow for three-dimensional diffusion of lithium ions and are generally represented by the following compositional formula (I).

[0099]

[0100] (0.8≦a in compositional formula (I) １ ≤ 1.5, 1.9 ≤ b１ ≤ 2.1, M １ (It contains at least one transition metal element, excluding Li.)

[0101] M １ Examples include Ni, Co, Mn, V, Al, etc. １ One type may be used alone, or two or more types may be used in any ratio and combination. １ From the viewpoint of improving the battery's cycle performance, Ni, Co, and Mn are preferred, and Ni and Mn are more preferred.

[0102] Examples of lithium transition metal composite oxides having a spinel structure include LiMn ２ O ４ LiCoMnO ４ LiNi ０．５ Mn １．５ O ４ LiCoVO ４ Examples include LiMn. A lithium transition metal composite oxide having a spinel structure may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of improving the battery cycle performance, LiMn ２ O ４ LiNi ０．５ Mn １．５ O ４ LiNi ０．５ Mn １．５ O ４ This is preferable.

[0103] Lithium transition metal composite oxides having an olivine structure allow for three-dimensional diffusion of lithium ions and are generally represented by the following compositional formula (II).

[0104]

[0105] (0.8≦a in compositional formula (II) ２ ≤ 1.5, 0.9 ≤ b ２ ≤ 1.1, M ２ (It contains at least one transition metal element, excluding Li.)

[0106] M ２Examples include Fe, Ni, Co, Mn, Al, etc. ２ One type may be used alone, or two or more types may be used in any ratio and combination. ２ From the viewpoint of improving the battery's cycle performance, Fe, Ni, Co, and Mn are preferred, with Fe and Mn being more preferred.

[0107] Examples of lithium transition metal composite oxides having an olivine structure include LiFePO ４ Examples include the following. A lithium transition metal composite oxide having an olivine structure may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of improving the battery cycle performance, the lithium transition metal composite oxide having an olivine structure is LiFePO ４ It is preferable.

[0108] Lithium transition metal composite oxides having a layered structure allow for three-dimensional diffusion of lithium ions and are generally represented by the following compositional formula (III).

[0109]

[0110] (0.8≦a in compositional formula (III) ３ ≤ 1.5, 0.5 ≤ b ３ ≤ 1.1, M ３ (It contains at least one transition metal element, excluding Li.)

[0111] M ３ Examples include Ni, Co, Mn, Al, Mg, Zr, Fe, Ti, Er, etc. ３ One type may be used alone, or two or more types may be used in any ratio and combination. ３ From the viewpoint of improving the battery's cycle performance, Ni, Co, Mn, Al, Mg, and Zr are preferred, and Ni, Co, Mn, and Al are more preferred.

[0112] Examples of lithium transition metal composite oxides having a layered structure include LiCoO ２ LiNiO ２ LiNi ０．９ Co ０．０５ Mn０．０５ O ２ LiNi ０．８５ Co ０．１ Al ０．０５ O ２ LiNi ０．８ 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 ０．３ Mn ０．２ 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 Examples include solid solutions thereof. A lithium transition metal composite oxide having a layered structure may be used alone, or two or more may be used in any ratio and combination.

[0113] From the viewpoint of increasing battery capacity, lithium transition metal composite oxides having a layered structure are preferred if they are represented by the following compositional formula (IV), and more preferably if they are represented by the following compositional formula (V).

[0114]

[0115] (0.8≦a in compositional formula (IV) ４ ≤ 1.1, 0.3 ≤ b ４ ≤0.98, 0.0 ≤c４ ≤ 0.7, 0.9 ≤ b ４ +c ４ ≤ 1.1, M ４ (This is at least one metallic element selected from the group consisting of Co, Mn, Al, Mg, Zr, Fe, Ti, and Er.)

[0116]

[0117] (0.8≦a in compositional formula (V) ５ ≤ 1.1, 0.3 ≤ b ５ ≤0.98, 0.01 ≤c ５ ≤0.7, 0.01 ≤d ５ ≤ 0.6, 0.9 ≤ b ５ +c ５ +d ５ ≤ 1.1, M ５ (This is at least one metallic element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti, and Er.)

[0118] M in the composition formula (IV) ４ This element is at least one metal element selected from the group consisting of Co, Mn, Al, Mg, Zr, Fe, Ti, and Er. From the viewpoint of improving the structural stability of lithium transition metal oxides and suppressing structural degradation during repeated charging and discharging, Co, Mn, and Al are preferred, and Co and Mn are more preferred.

[0119] b in the empirical formula (IV) ４ b is 0.3 or higher, and from the viewpoint of improving the battery's cycle performance, 0.4 or higher is preferable, and 0.5 or higher is more preferable. ４ The value is 0.98 or less, and from the viewpoint of battery safety, 0.97 or less is preferred, and 0.96 or less is more preferred.

[0120] Examples of lithium transition metal composite oxides represented by compositional formula (IV) include LiNi ０．９ Co ０．０５ Mn ０．０５ O ２ LiNi ０．８５ Co ０．１ Al ０．０５ O ２ LiNi ０．８ Co ０．１５ Al０．０５ 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 ０．９ Co ０．０３ Al ０．０７ O ２ LiNi ０．６１ Co ０．２ Mn ０．１９ O ２ Examples include the following. The lithium transition metal composite oxide represented by compositional formula (IV) may be used alone, or two or more may be used in any ratio and combination.

[0121] M in the composition formula (V) ５ This element is at least one metal element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti, and Er. From the viewpoint of improving the structural stability of lithium transition metal oxides and suppressing structural degradation during repeated charging and discharging, Mn and Al are preferred, and Mn is more preferred.

[0122] b in the empirical formula (V) ５ b is 0.3 or higher, preferably 0.4 or higher, and more preferably 0.5 or higher, from the viewpoint of increasing the energy density of the battery. ５The value is 0.98 or less, and from the viewpoint of battery safety, 0.97 or less is preferred, and 0.96 or less is more preferred.

[0123] d in the empirical formula (V) ５ It is 0.01 or greater, and from the viewpoint of battery safety, 0.1 or greater is preferred. Also, d ５ The value is 0.6 or less, and from the viewpoint of increasing the energy density of the battery, 0.5 or less is preferable.

[0124] Examples of lithium transition metal composite oxides represented by compositional formula (V) include LiNi ０．９ Co ０．０５ Mn ０．０５ O ２ LiNi ０．８５ Co ０．１ Al ０．０５ O ２ LiNi ０．８ 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 ０．９ Co ０．０３ Al ０．０７ O ２ LiNi ０．６１ Co ０．２ Mn ０．１９ O２ Examples include the following. The lithium transition metal composite oxide represented by compositional formula (V) may be used alone, or two or more may be used in any ratio and combination.

[0125] The lithium transition metal composite oxide may further contain elements other than those included in the aforementioned compositional formulas (I) to (V) (other elements).

[0126] [2-2-1-2. Surface Coating] In this embodiment, the positive electrode active material may be one in which a substance with a different composition from the positive electrode active material (surface-adhered substance) is attached to the surface of the positive electrode active material. Examples of surface-adhered substances include oxides such as aluminum oxide; sulfates such as lithium sulfate; and carbonates such as lithium carbonate. One type of surface-adhered substance may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of battery safety, lithium carbonate is preferred as the surface-adhered substance. The surface-adhered substance can be attached to the surface of the positive electrode active material by dissolving it in a solvent or dispersing it in a dispersion medium and impregnating the positive electrode active material with it.

[0127] The content of surface-adhered material relative to the total positive electrode active material is preferably 1 μmol / g or more and 1 mmol / g or less. Here, from the viewpoint of battery safety, the above content is preferably 1 μmol / g or more, and more preferably 10 μmol / g or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 1 mmol / g or less, and more preferably 0.5 mmol / g or less. In this specification, surface-adhered material attached to the surface of the positive electrode active material is also included in the positive electrode active material.

[0128] [2-2-2. Method for Manufacturing the Positive Electrode] Examples of methods for manufacturing the positive electrode in this embodiment include a method of obtaining a positive electrode by forming a positive electrode active material layer on a current collector by pressure bonding, and a method of obtaining a positive electrode by forming a positive electrode active material layer on a current collector by coating. From the viewpoint of a simple manufacturing process and excellent productivity, the method of obtaining a positive electrode by forming a positive electrode active material layer on a current collector by coating is preferred.

[0129] The positive electrode active material layer further includes a positive electrode active material and a binder, as well as, if necessary, a conductive material and a thickening agent.

[0130] In the method of obtaining a positive electrode by forming a positive electrode active material layer on a current collector by pressure bonding, a preferred method is one in which, from the viewpoint of a simple manufacturing process and excellent productivity, a positive electrode active material and binder, as well as conductive material and thickener as needed, are dry-mixed to form a sheet, and then pressure-bonded onto a positive electrode current collector to obtain the positive electrode.

[0131] In the method of obtaining a positive electrode by forming a positive electrode active material layer on a current collector by coating, a method is preferred from the viewpoint of simplicity of the manufacturing process and excellent productivity, in which, in addition to the positive electrode active material and binder, a conductive material and a thickener are further dissolved in a solvent or dispersed in a dispersion medium as needed, and the mixture is coated onto the positive electrode current collector and dried to obtain the positive electrode.

[0132] [2-2-2-1. Positive Electrode Active Material Layer] The content of positive electrode active material in the positive electrode active material layer is preferably 80 to 99.5% by mass. Here, from the viewpoint of increasing the energy density of the battery, the above content is preferably 80% by mass or more, and more preferably 90% by mass or more. Also, from the viewpoint of improving the handling of the positive electrode, the above content is preferably 99.5% by mass or less, and more preferably 99% by mass or less. Here, if two or more types of positive electrode active materials are included, the above content refers to the total content of those materials. In this specification, the identification of positive electrode active material and the content of positive electrode active material are measured by high-frequency inductively coupled plasma (ICP) emission spectroscopy after wet decomposition of the sample. If it is difficult to identify positive electrode active material or determine the content of positive electrode active material by high-frequency inductively coupled plasma (ICP) emission spectroscopy alone, other analyses such as X-ray photoelectron spectroscopy (XPS), X-ray fluorescence (XRF) analysis, and energy-dispersive X-ray spectroscopy (EDS) analysis may be used in combination.

[0133] Examples of binders include fluororesins such as polyvinyl fluoride, polyvinylidene fluoride, and polytetrafluoroethylene; cyano group-containing resins such as polyacrylonitrile and polyvinylidene cyanide; and modified versions thereof, derivatives, random copolymers, alternating copolymers, graft copolymers, and block copolymers. One binder may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of weather resistance, chemical resistance, heat resistance, and flame retardancy, fluororesins and cyano group-containing resins are preferred as binders.

[0134] When a resin is used as a binder, the weight-average molecular weight of the resin is preferably 10,000 to 3,000,000. Here, from the viewpoint of improving the strength of the positive electrode, the weight-average molecular weight is preferably 10,000 or more, more preferably 50,000 or more, and even more preferably 100,000 or more. Furthermore, from the viewpoint of ease of forming the positive electrode, the weight-average molecular weight is preferably 3,000,000 or less, more preferably 950,000 or less, and even more preferably 900,000 or less.

[0135] The binder content in the positive electrode active material layer is preferably 0.1 to 20% by mass. Here, from the viewpoint of battery durability, the above content is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 20% by mass or less, and more preferably 10% by mass or less.

[0136] Examples of conductive materials include metallic materials such as copper and nickel; graphite such as natural graphite and artificial graphite; carbon black such as acetylene black; and carbon-based materials such as amorphous carbon such as needle coke. One type of conductive material may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of enhancing conductivity, carbon black is preferred as the conductive material.

[0137] When the positive electrode active material layer contains a conductive material, the content of the conductive material in the positive electrode active material layer is preferably 0.01 to 15% by mass. Here, from the viewpoint of increasing conductivity, the above content is preferably 0.01% by mass or more, and more preferably 0.1% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 15% by mass or less, and more preferably 10% by mass or less.

[0138] From the viewpoint of increasing the packing density of the positive electrode active material, it is preferable to compact the positive electrode active material layer using a hand press, roller press, or the like. The density of the positive electrode active material layer is 1.5 to 4.5 g / cm³. ３ This is preferable. Here, from the viewpoint of increasing the energy density of the battery, the above density is 1.5 g / cm³. ３ The above is preferable, specifically 2.0 g / cm³. ３The above is more preferable. Furthermore, from the viewpoint of impregnating with electrolyte, the density is 4.5 g / cm³. ３ The following is preferable: 4.0 g / cm³ ３ The following are preferable.

[0139] The thickness of the positive electrode active material layer is preferably 10 to 500 μm. Here, from the viewpoint of increasing the energy density of the battery, the thickness is preferably 10 μm or more, and more preferably 15 μm or more. Also, from the viewpoint of improving the rate characteristics of the battery, the thickness is preferably 500 μm or less, and more preferably 300 μm or less. The positive electrode active material layer may be formed on one surface of the current collector, or on both surfaces of the current collector.

[0140] [2-2-2-2. Current Collector] Examples of materials for the current collector include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum. From the viewpoint of increasing the energy density of the battery, aluminum is preferred as the material for the current collector.

[0141] Examples of current collector shapes include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punched metal, and foamed metal. From the viewpoint of improving the handling of the positive electrode, metal foil and metal thin film are preferred as current collector shapes. The metal thin film may be formed in a mesh shape.

[0142] When the shape of the current collector is plate-shaped or film-shaped, the thickness of the current collector is preferably 1 μm or more and 1 mm or less. Here, from the viewpoint of improving the handling of the positive electrode, the above thickness is preferably 1 μm or more, and more preferably 2 μm or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above thickness is preferably 1 mm or less, and more preferably 0.5 mm or less.

[0143] [2-2-3. Surface Coating of the Positive Electrode] The positive electrode may be one in which a substance with a different composition from the positive electrode active material (surface-adhered substance) is attached to the surface of the positive electrode. The same explanation as for the surface-adhered substance in [3-2-1-2. Surface Coating] applies to the surface-adhered substance on the surface of the positive electrode, and the preferred embodiments are also the same. In this specification, the surface-adhered substance attached to the surface of the positive electrode is also included in the positive electrode.

[0144] [2-3. Negative Electrode] In this embodiment, the negative electrode includes a negative electrode active material on at least a portion of the surface of the current collector.

[0145] [2-3-1. Negative Electrode Active Material] The negative electrode active material in this embodiment is not particularly limited as long as it is capable of electrochemically intercalating and releasing metal ions. Examples of negative electrode active materials include carbon-based materials and metal materials. The negative electrode active material may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of cycle characteristics, continuous charging characteristics and safety, carbon-based materials, metal materials, and mixtures of carbon-based materials and metal materials are preferred as negative electrode active materials.

[0146] [2-3-1-1. Carbon-based materials] Examples of carbon-based materials that serve as the negative electrode active material in this embodiment include natural graphite such as uncoated natural graphite, amorphous carbon-coated natural graphite, graphite-coated natural graphite, and resin-coated natural graphite; artificial graphite; amorphous carbon, etc. One type of carbon-based material may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of increasing battery capacity, natural graphite is preferred as the carbon-based material.

[0147] Examples of natural graphite include scaly natural graphite, flake-like natural graphite, and natural graphite obtained by treating these graphites with processes such as spheroidization or densification. Natural graphite may be used individually or in any ratio and combination of two or more types. From the viewpoint of packing properties and charge / discharge rate characteristics, spheroidized natural graphite is preferred.

[0148] [2-3-1-2. Physical Properties of Carbon-Based Materials] The d002 value (d value (interlayer distance) of the lattice plane (002 plane)) of carbon-based materials is theoretically 0.3354 nm or higher, and from the viewpoint of increasing battery capacity, it is preferably 0.3360 nm or lower, and more preferably 0.3357 nm or lower. In this specification, the d002 value is measured by X-ray diffraction according to the Japan Society for the Promotion of Science (JSPS) method.

[0149] The Lc (crystallite size) of carbon-based materials is preferably 0.9 nm or larger, and more preferably 1.0 nm or larger, from the viewpoint of increasing battery capacity. While there is no particular upper limit to the Lc (crystallite size), it is usually 500 nm or smaller. In this specification, the Lc value is measured by X-ray diffraction according to the Japan Society for the Promotion of Science (JSPS) method.

[0150] The average particle size of the carbon-based material is preferably 1 to 100 μm. Here, from the viewpoint of increasing battery capacity, the average particle size is preferably 1 μm or more, and more preferably 3 μm or more. Also, from the viewpoint of suppressing resistance, the average particle size is preferably 100 μm or less, and more preferably 50 μm or less. In this specification, the average particle size of particles such as carbon-based material is the volume-based average particle size (median diameter), and is measured by laser diffraction / scattering method.

[0151] The Raman R value of carbon-based materials is preferably 0.01 to 1.5. Here, from the viewpoint of suppressing resistance, the Raman R value is preferably 0.01 or higher, and more preferably 0.1 or higher. Furthermore, from the viewpoint of increasing battery capacity, the Raman R value is preferably 1.5 or lower, and more preferably 1 or lower. In this specification, the Raman R value is measured by argon ion laser Raman spectroscopy.

[0152] The Raman full width at half maximum (FWHM) for carbon-based materials is 10–100 cm. －１ This is preferable. Here, from the viewpoint of suppressing resistance, the above Raman half-width is 10 cm. －１ The above is preferable, 20 cm －１ The above is preferable. Also, from the viewpoint of increasing battery capacity, the above Raman half-width is 100 cm. －１ The following is preferable: 80 cm －１ The following is more preferable. In this specification, the Raman full width at half maximum is measured by argon ion laser Raman spectroscopy.

[0153] The specific surface area of ​​carbon-based materials ranges from 0.1 to 100 m². ２ / g is preferred. Here, from the viewpoint of suppressing resistance, the specific surface area is 0.1m². ２ Preferably 0.2 m / g or more, ２ A value of 100 m² or more is more preferable. Furthermore, from the viewpoint of increasing battery capacity, the above specific surface area should be 100 m². ２Preferably less than / g, and 50m ２ It is more preferable that the amount is less than or equal to / g. In this specification, the specific surface area is measured by the BET method.

[0154] [2-3-1-3. Metallic Material] The metallic material that serves as the negative electrode active material in this embodiment is a material containing a metallic element and / or a metalloid element that can be alloyed with an alkali metal. Furthermore, the metallic elements constituting the metallic material are metallic elements and / or metalloid elements.

[0155] Examples of metallic materials include metals such as Fe, Co, Sb, Bi, Pb, Ni, Ag, Si, Sn, Al, Zr, Cr, V, Mn, As, Nb, Mo, Cu, Zn, Ge, In, Ti, and W; and compounds of these metals (metallic compounds). The metallic material may be used individually, in any ratio and combination of two or more metals, or as an alloy of two or more metals. Examples of metallic compounds include metal oxides, metal nitrides, and metal carbides. The metallic compound may be an oxide, nitride, or carbide of an alloy of two or more metals.

[0156] From the viewpoint of capacity and cycle life, the metallic material is preferably at least one metal selected from the group consisting of Si, Sn, As, Sb, Al, Zn, and W, or a compound thereof, and from the viewpoint of high capacity, Si and Si compounds are more preferred. In this specification, Si and Si compounds are collectively referred to as Si-based materials.

[0157] Examples of Si compounds include Si oxides, Si nitrides, Si carbides, oxides of Si nitrides, and oxides of Si carbides (silicon oxycarbide). Si compounds may be used individually or in any ratio and combination of two or more types.

[0158] Si oxides are, for example, SiO ｘ１ It is expressed as, 0 < x １ <2 satisfies. Si nitrides are, for example, Si ３ N ４ SiN ｘ２ It is expressed as, 0 < x ２ The condition ≤ 1.3 is satisfied. Si carbides are, for example, SiCｘ３ It is expressed as follows, and 0.9 ≤ x ３ The condition ≤ 1.1 is satisfied. Oxides of Si nitrides include, for example, SiN ｙ１ O ｚ１ It is expressed as follows, where 1 ≤ y １ ≤ 10, 0 < z １ The condition ≤ 1 is satisfied. Oxides of Si carbides include, for example, SiC ｙ２ O ｚ２ It is expressed as follows, where 1 ≤ y ２ ≤ 10, 0 < z ２ It satisfies ≤ 1.

[0159] Si-based materials include Si, Si oxide, and Si carbide oxides. Si is preferred because it allows for easy movement of alkali metal salts such as lithium ions, enabling high capacity. Si oxide is preferred because it has a larger theoretical capacity compared to graphite. Si carbide oxide is also preferred because it has a larger theoretical capacity compared to graphite.

[0160] When used in batteries that do not require high output performance, metal composite oxides are preferred as metal materials from the viewpoint of battery durability. Examples of metal composite oxides include Li ４／３ Ti ５／３ O ４ Li １ Ti ２ O ４ Li ４／５ Ti １１／５ O ４ Lithium titanium composite oxides such as Li ４／３ Ti ４／３ Al １／３ O ４Examples include lithium titanium composite oxides in which part of lithium and / or titanium is replaced with other metals (e.g., Al, Ga, Cu, Zn, etc.). Metal composite oxides may be used individually or in any ratio and combination of two or more types. From the viewpoint of high current density charge / discharge characteristics, lithium titanium composite oxides and lithium titanium composite oxides in which part of lithium and / or titanium is replaced with other metals are preferred, and from the viewpoint of reducing output resistance, lithium titanium composite oxides having a spinel structure and lithium titanium composite oxides having a spinel structure in which part of lithium and / or titanium is replaced with other metals are more preferred. ４／３ Ti ５／３ O ４ Li １ Ti ２ O ４ Li ４／５ Ti １１／５ O ４ Li ４／３ Ti ４／３ Al １／３ O ４ That is even more preferable.

[0161] When the metal material is in the form of particles, the average particle size of the metal particles is preferably 0.005 to 10 μm. Here, from the viewpoint of increasing battery capacity, the average particle size is preferably 0.005 μm or more, and more preferably 0.1 μm or more. Furthermore, from the viewpoint of suppressing resistance, the average particle size is preferably 10 μm or less, and more preferably 5 μm or less.

[0162] [2-3-1-4. Mixture of carbon-based material and metal material] The mixture of carbon-based material and metal material that serves as the negative electrode active material in this embodiment may be a mixture in which the carbon-based material and metal material are mixed in an independent state, or it may be a composite in which the metal material is present on the surface or inside the carbon-based material.

[0163] When a mixture of carbon-based material and metal material is used as the negative electrode active material, the content of the carbon-based material relative to the total negative electrode active material is preferably 1 to 95% by mass. Here, from the viewpoint of increasing the conductivity of the negative electrode, the above content is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less.

[0164] When a mixture of carbon-based material and metal material is used as the negative electrode active material, the content of the metal material relative to the total negative electrode active material is preferably 5 to 99% by mass. Here, from the viewpoint of increasing the energy density of the battery, the above content is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more. Furthermore, from the viewpoint of suppressing capacity loss during battery operation due to deterioration of the metal material, the above content is preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 80% by mass or less.

[0165] [2-3-2. Method for Manufacturing the Negative Electrode] Examples of methods for manufacturing the negative electrode in this embodiment include a method of obtaining a positive electrode by forming a negative electrode active material layer on a current collector by pressure bonding, and a method of obtaining a negative electrode by forming a negative electrode active material layer on a current collector by coating. From the viewpoint of a simple manufacturing process and excellent productivity, the method of obtaining a negative electrode by forming a negative electrode active material layer on a current collector by coating is preferred.

[0166] The negative electrode active material layer further includes, as necessary, a conductive material, a thickener, and a filler, in addition to the negative electrode active material and a binder.

[0167] In the method of obtaining a negative electrode by forming a negative electrode active material layer on a current collector by pressure, a preferred method is one in which, from the viewpoint of a simple manufacturing process and excellent productivity, a negative electrode active material and binder, as well as conductive material, thickener, and filler as needed, are dry-mixed to form a sheet, and then pressure-bonded onto a negative electrode current collector to obtain the negative electrode.

[0168] In the method of obtaining a negative electrode by forming a negative electrode active material layer on a current collector by coating, a preferred method is one in which, from the viewpoint of a simple manufacturing process and excellent productivity, a slurry is obtained by coating the negative electrode current collector with a slurry in which a negative electrode active material and binder are dispersed in a dispersion medium, as needed, a conductive material, a thickener and a filler, and then drying it.

[0169] [2-3-2-1. Negative Electrode Active Material Layer] The content of negative electrode active material in the negative electrode active material layer is preferably 80 to 99.5% by mass. Here, from the viewpoint of increasing the energy density of the battery, the above content is preferably 80% by mass or more, and more preferably 90% by mass or more. Also, from the viewpoint of improving the handling of the negative electrode, the above content is preferably 99.5% by mass or less, and more preferably 99% by mass or less. Here, if two or more types of negative electrode active materials are included, the above content refers to the total content of those materials. In this specification, the identification of negative electrode active materials and the content of negative electrode active materials are measured by high-frequency inductively coupled plasma (ICP) emission spectroscopy after alkali fusion of the sample.

[0170] Examples of binders include rubbery polymers such as styrene-butadiene rubber (SBR), isoprene rubber, butadiene rubber, fluororubber, acrylonitrile-butadiene rubber (NBR), and ethylene-propylene rubber; and fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and tetrafluoroethylene-ethylene copolymer. A single binder may be used, or two or more binders may be used in any ratio and combination. From the viewpoint of battery durability, styrene-butadiene rubber is preferred as the binder.

[0171] The binder content in the negative electrode active material layer is preferably 0.1 to 20% by mass. Here, from the viewpoint of battery durability, the above content is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 20% by mass or less, and more preferably 10% by mass or less.

[0172] When a rubbery polymer is used as the main component of the binder, the binder content in the negative electrode active material layer is preferably 0.1 to 5% by mass. Here, from the viewpoint of battery durability, the above content is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 5% by mass or less, and more preferably 2% by mass or less.

[0173] When a fluorine-based polymer is used as the main component of the binder, the binder content in the negative electrode active material layer is preferably 1 to 15% by mass. Here, from the viewpoint of battery durability, the above content is preferably 1% by mass or more, and more preferably 2% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 15% by mass or less, and more preferably 10% by mass or less.

[0174] Examples of conductive materials include carbon black such as acetylene black; and carbon-based materials such as amorphous carbon such as needle coke. One type of conductive material may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of enhancing conductivity, carbon black is preferred as the conductive material.

[0175] When the negative electrode active material layer contains a conductive material, the content of the conductive material in the negative electrode active material layer is preferably 0.01 to 15% by mass. Here, from the viewpoint of increasing conductivity, the above content is preferably 0.01% by mass or more, and more preferably 0.1% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 15% by mass or less, and more preferably 10% by mass or less.

[0176] Examples of thickening agents include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, and their salts. A single thickening agent may be used, or two or more may be used in any ratio and combination. From the viewpoint of battery durability, carboxymethylcellulose is preferred as the thickening agent.

[0177] When the negative electrode active material layer contains a thickening agent, the content of the thickening agent in the negative electrode active material layer is preferably 0.5 to 5% by mass. Here, from the viewpoint of battery durability, the above content is preferably 0.5% by mass or more, and more preferably 1% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 5% by mass or less, and more preferably 2% by mass or less.

[0178] From the viewpoint of increasing the packing density of the negative electrode active material, it is preferable to compact the negative electrode active material layer using a hand press, roller press, or the like. The density of the negative electrode active material layer is 1.0 to 2.2 g / cm³. ３ This is preferable. Here, from the viewpoint of increasing the energy density of the battery, the above density is 1.0 g / cm³. ３ The above is preferable, 1.5 g / cm³ ３ The above is more preferable. Furthermore, from the viewpoint of impregnating with electrolyte, the density is 2.2 g / cm³. ３ The following is preferable: 2.0 g / cm³ ３ The following are preferable.

[0179] The thickness of the negative electrode active material layer is preferably 10 to 500 μm. Here, from the viewpoint of increasing the energy density of the battery, the thickness is preferably 10 μm or more, and more preferably 15 μm or more. Also, from the viewpoint of improving the rate characteristics of the battery, the thickness is preferably 500 μm or less, and more preferably 300 μm or less. The negative electrode active material layer may be formed on one surface of the current collector, or on both surfaces of the current collector.

[0180] [2-3-2-2. Current Collector] Examples of materials for the current collector include metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel. Copper is preferred as the material for the current collector because it does not alloy with alkali metals and is inexpensive.

[0181] Examples of current collector shapes include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punched metal, and foamed metal. From the viewpoint of improving the handling of the negative electrode, metal foil and metal thin film are preferred as current collector shapes. The metal thin film may be formed in a mesh shape.

[0182] When the shape of the current collector is plate-like, film-like, etc., the thickness of the current collector is preferably 1 μm or more and 1 mm or less. Here, from the viewpoint of improving the handling property of the negative electrode, the above thickness is preferably 1 μm or more, more preferably 2 μm or more. Further, from the viewpoint of increasing the energy density of the battery, the above thickness is preferably 1 mm or less, more preferably 0.5 mm or less.

[0183] [2-3-3. Surface coating of negative electrode] For the negative electrode, a negative electrode having a substance (surface adherent substance) with a composition different from that of the negative electrode active material adhered to the surface of the negative electrode may be used. The surface adherent substance on the surface of the negative electrode is applicable to the same explanation as the surface adherent substance on the surface of the positive electrode in [2-2-3. Surface coating of positive electrode], and the preferred embodiments are also the same. In this specification, the surface adherent substance adhered to the surface of the negative electrode is also included in the negative electrode.

[0184] [3-4. Separator] The separator in the non-aqueous electrolyte secondary battery according to this embodiment includes a base material layer and a coat layer. Among these, the total thickness of the above coat layer is preferably 1.0 to 10.0 μm.

[0185] Examples of the base material layer of the separator include woven fabric, non-woven fabric, porous film, etc. Among these, from the viewpoint of strength, a porous film is preferable, and from the viewpoint of the liquid retention property of the non-aqueous electrolyte, a non-woven fabric is preferable.

[0186] As the material of the base material layer of the separator, known materials can be used within a range that does not significantly impair the effects of the present invention. For example, from the viewpoint of the shutdown function, polyolefins such as polyethylene and polypropylene are preferable.

[0187] As the base material layer of the separator, a material in which these resins are combined may be used, for example, a three-layer structure in which a polypropylene layer is laminated on both sides of a polyethylene layer or a three-layer structure of polypropylene may be used. [[ID=十六]]

[0188] The thickness of the base material layer may be, for example, 4 to 40 μm. Here, the above thickness is usually 4 μm or more, preferably 5 μm or more, more preferably 6 μm or more, and usually 40 μm or less, preferably 30 μm or less, more preferably 25 μm.

[0189] In the separator according to this embodiment, the coating layer is preferably laminated on one or both surfaces of the base material layer, and it is more preferable that the coating layer is laminated on at least the surface of the base material layer facing the positive electrode.

[0190] As the material of the coating layer, known materials can be used as long as the effects of the present invention are not significantly impaired. For example, it may contain at least one selected from the group consisting of inorganic particles and polymer materials, and may further contain a binder. Among them, by using a coating layer containing inorganic particles and a binder, gas generation during high-temperature charge storage can be more preferably suppressed, and the thermal stability of the non-aqueous electrolyte secondary battery can be made higher, so it is more preferable.

[0191] Examples of the inorganic particles of the coating layer include, for example, alumina (Al ２ O ３ ), magnesia (MgO), silica (SiO ２ ), titania (TiO ２ ) and other inorganic oxides, nitrides such as aluminum nitride and silicon nitride, metal hydroxides such as calcium hydroxide, magnesium hydroxide, and aluminum hydroxide, clay minerals such as mica, talc, boehmite, zeolite, apatite, and kaolin, and glass fibers. Among them, alumina, boehmite, and magnesia are preferable, and alumina and boehmite are more preferably used. These have a high melting point and excellent heat resistance. Also, the Mohs hardness is relatively high, and they are also excellent in mechanical strength and durability. Furthermore, since they are relatively inexpensive, the raw material cost can be suppressed.

[0192] The polymer material of the coating layer is preferably made of a material other than polyolefin. Specifically, examples of the polymer material include polyamide, polyaramide, para-aramide, polystyrene, polyacrylate ester, polymethacrylate ester, polycarbonate, polyethylene terephthalate, polyphenylene sulfide, polysulfone, polyethersulfone, polytetrafluoroethylene, polyimide, polyetherimide, melamine, and polyvinylidene fluoride.

[0193] Suitable binders include polyacrylic acid-based binders such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), poly-N-vinylacetamide (PNVA), polyvinylpyrrolidone (PVP), styrene / butadiene rubber (SBR), polyacrylic acid (PAA), cross-linked polyacrylic acid (CLPAH), and sodium polyacrylate (PAANA), as well as polyimide-based binders and inorganic binders. Among these, PVDF, PTFE, PNVA, PVP, and PAA are preferred, and PVDF, PTFE, and PAA are more preferred. There are no particular restrictions on the binder content, but it is preferably 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the inorganic particles that form the coating layer. Here, the above content is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2.5 parts by mass or more. Furthermore, the above content ratio is preferably 10 parts by mass or less, more preferably 5.5 parts by mass or less, and even more preferably 3.5 parts by mass or less. Here, if two or more types of binders are included, it is preferable that the total content ratio of them is within the above range.

[0194] In this specification, "total separator thickness" refers to the total thickness of the laminate, including the substrate layer and the coating layer of the separator. The total separator thickness is measured using a micrometer (e.g., a digital micrometer) at multiple locations at room temperature, according to a standard method, and the average value is defined as the thickness. The measurement should be performed on a flat portion of the separator. The substrate layer thickness and the coating layer thickness are calculated by apportioning the total separator thickness obtained with the micrometer based on the film thickness ratio of the substrate layer and the coating layer. The film thickness ratio of the substrate layer and the coating layer is calculated by observing a cross-section of a separator fabricated by the broad ion beam method (BIB method) with a scanning electron microscope (SEM) after imparting conductivity to the cross-section.

[0195] The total thickness of the coating layer is preferably 1.0 to 10.0 μm, as this maintains heat resistance and meltdown suppression without excessively high electrical resistance, and more preferably 1.2 to 6.5 μm. From the viewpoint of maintaining the meltdown suppression effect and suppressing gas generation within a suitable range of anions represented by general formula (1), the total thickness of the coating layer is preferably 1.0 μm or more, more preferably 1.2 μm or more, and even more preferably 1.4 μm or more. Furthermore, from the viewpoint of minimizing the influence of electrical resistance and suppressing gas generation within a suitable range of anions represented by general formula (1), the total thickness of the coating layer is preferably 10.0 μm or less, more preferably 6.5 μm or less, and even more preferably 4.5 μm or less. Note that the total thickness of the coating layer refers to the thickness of the coating layer if it is formed on only one side of the substrate layer, and the sum of the thicknesses of the coating layers on both sides if it is formed on both sides of the substrate layer.

[0196] In this embodiment, the ratio of the total thickness of the positive and negative electrode coating layers (total coating layer thickness) to the thickness of the base material layer {total coating layer thickness (μm) / base material layer thickness (μm)} of the separator is preferably 0.10 to 0.90. Here, from the viewpoint of maintaining heat resistance and meltdown suppression effects without the electrical resistance becoming too large, while also enhancing the effect of suppressing gas increase, which is an effect of the present invention, the above ratio is preferably 0.10 or higher, more preferably 0.11 or higher, even more preferably 0.13 or higher, and also preferably 0.90 or lower, more preferably 0.85 or lower, even more preferably 0.80 or lower, and even more preferably 0.78 or lower.

[0197] In this embodiment, the ratio of the thickness of the positive electrode coating layer to the thickness of the substrate layer {thickness of the positive electrode coating layer (μm) / thickness of the substrate layer (μm)} of the separator is preferably 0.10 to 0.70. Here, from the viewpoint of maintaining heat resistance and meltdown suppression effects without the electrical resistance becoming too large, while enhancing the effect of suppressing gas increase, which is an effect of the present invention, the above ratio is preferably 0.10 or more, more preferably 0.11 or more, even more preferably 0.13 or more, and also preferably 0.70 or less, more preferably 0.60 or less, even more preferably 0.50 or less, even more preferably 0.45 or less, and thereafter preferably 0.40 or less, 0.35 or less, 0.30 or less, 0.25 or less, in that order of preference, and particularly preferably 0.20 or less.

[0198] Furthermore, in this embodiment, it is more preferable that the separator has a {total coating layer thickness (μm) / substrate layer thickness (μm)} of 0.10 to 0.90, and that the {coating layer thickness (μm) on the positive electrode side / substrate layer thickness (μm)} also satisfies both of these conditions.

[0199] In this embodiment, the permeability (Gurley) of the separator is preferably 150 to 280 seconds / 100 mL. Here, from the viewpoint of suppressing an increase in gas generation while also minimizing an increase in electrochemical resistance, the above permeability is preferably 150 seconds / 100 mL or more, more preferably 160 seconds / 100 mL or more, even more preferably 170 seconds / 100 mL or more, and also preferably 280 seconds / 100 mL or less, more preferably 270 seconds / 100 mL or less, and even more preferably 260 seconds / 100 mL or less. The above permeability is a value measured in accordance with JIS P 8117:2009.

[0200] [2-5. Battery Design] [2-5-1. Electrode Group] The electrode group in this embodiment may be a stacked structure in which the positive electrode and the negative electrode are stacked with a separator in between, or a wound structure in which the positive electrode and the negative electrode are wound in a spiral shape with a separator in between.

[0201] The electrode group occupancy rate, that is, the volume ratio of the electrode group to the total internal volume of the battery, is preferably 40 to 90%. Here, from the viewpoint of increasing the energy density of the battery, the electrode group occupancy rate is preferably 40% or more, and more preferably 50% or more. Furthermore, from the viewpoint of impregnation with electrolyte, the electrode group occupancy rate is preferably 90% or less, and more preferably 80% or less.

[0202] [2-5-2. Current Collection Structure] In this embodiment, when the electrode group has a laminated structure, a structure formed by bundling the metal core portions of each electrode layer and welding them to a terminal, or a structure that reduces resistance by providing multiple terminals within the electrode, is preferably used. Furthermore, when the electrode group has a wound structure, a structure that reduces resistance by providing multiple lead structures to each electrode and bundling them to a terminal is preferably used.

[0203] [2-5-3. Protective Elements] Examples of protective elements include PTC (Positive Temperature Coefficient) elements whose resistance increases with heat generation due to excessive current, thermal fuses, thermistors, and current interruption valves that interrupt the current flowing through the circuit due to a rapid rise in internal pressure or temperature of the battery during abnormal heat generation. One type of protective element may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of battery safety, protective elements that do not operate under normal high-current use are preferred, but it is even more preferable to design the battery so that abnormal heat generation or thermal runaway does not occur even without protective elements.

[0204] [2-5-4. Outer casing] The battery according to this embodiment is typically constructed by housing the positive electrode, negative electrode, separator, and electrolyte inside an outer casing.

[0205] Examples of materials for the exterior include metals such as iron, aluminum, and aluminum alloys; and laminated films. From the viewpoint of weight reduction and cost, metals and laminated films are preferred for the exterior material, and from the viewpoint of pressure resistance for operating the current interruption valve, iron is more preferred.

[0206] When metal is used as the material for the exterior, the structure of the exterior may be a sealed structure formed by welding metals together using laser welding, resistance welding, or ultrasonic welding, or it may be a crimped structure using metal via a resin gasket.

[0207] Examples of exterior shapes include cylindrical, rectangular, laminated, coin-shaped, and large. From the viewpoint of increasing the energy density of the battery, cylindrical, rectangular, and laminated exteriors are preferred.

[0208] [2-6. Method for Manufacturing a Battery] The method for manufacturing a battery according to this embodiment includes the steps of housing the positive electrode, negative electrode and separator in an outer casing, and injecting the non-aqueous electrolyte according to this embodiment into the outer casing.

[0209] The same description as for the non-aqueous electrolyte described above in [1-1. Non-aqueous electrolyte] applies to the non-aqueous electrolyte, and the preferred embodiments are also the same. The non-aqueous electrolyte may be used in combination with other electrolytes as long as it does not significantly impair the effects of the present invention.

[0210] The positive electrode in the battery manufacturing method is described in the same way as the positive electrode of the battery described above in [2-2. Positive Electrode], and the preferred embodiment is also the same.

[0211] The negative electrode in the battery manufacturing method is described in the same way as the negative electrode of the battery described above in [2-3. Negative Electrode], and the preferred embodiment is also the same.

[0212] The separator in the battery manufacturing method is described in the same way as the separator in the battery described above in [3-4. Separator], and the preferred embodiment is also the same.

[0213] The same description as for the battery casing in the method of manufacturing the battery applies to the casing of the battery described above in [2-5-4. Casing], and the preferred embodiments are also the same.

[0214] The steps of housing the positive electrode, negative electrode, and separator in the outer casing and injecting the non-aqueous electrolyte into the outer casing can be performed in any order. However, from the viewpoint of impregnating the outer casing with the non-aqueous electrolyte, it is preferable to perform the step of injecting the non-aqueous electrolyte into the outer casing after the step of housing the positive electrode, negative electrode, and separator in the outer casing.

[0215] [2-7. Applications] From the perspective of being repeatedly used for various applications, the battery according to this embodiment is preferably a non-aqueous electrolyte secondary battery, more preferably an alkali ion secondary battery, and even more preferably a lithium ion secondary battery.

[0216] The battery according to this embodiment can be used for various known applications. Specific examples of applications include, for example, notebook computers, pen input computers, mobile computers, e-book players, mobile phones, mobile faxes, mobile copiers, mobile printers, mobile audio players, small video cameras, headphone stereos, video movies, liquid crystal TVs, handy cleaners, portable CDs, mini discs, transceivers, electronic notebooks, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, automobiles, motorcycles, motorized bicycles, bicycles, lighting fixtures, toys, game devices, watches, power tools, strobes, cameras, household backup power supplies, industrial backup power supplies, power supplies for load leveling, natural energy storage power supplies, etc.

[0217] Among them, the battery according to this embodiment is excellent in the effect of suppressing gas generation in an over-discharged state and can be preferably used for vehicles such as automobiles, motorcycles, motorized bicycles, and bicycles from the perspective of safe use, and can be particularly preferably used for automobiles. That is, the present invention also relates to a vehicle including the above battery.

[0218] Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0219] 《Raw Materials》 In the following examples and comparative examples, the following were used as raw materials for manufacturing the non-aqueous electrolyte.

[0220] - Compound (A): A compound having an anion represented by the general formula (1) as a constituent anion, which is a compound represented by the following formula

[0221]

[0222] - Instead of the compound having an anion represented by the general formula (1) as a constituent anion, Compound (B) used in the comparative example: A compound represented by the following formula

[0223]

[0224] ・Electrolyte LiPF ６ • Non-aqueous solvents: ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC) • Other compounds: vinylene carbonate (VC)

[0225] 《Manufacturing of Non-Aqueous Electrolyte Secondary Batteries: Examples 1-3, Comparative Examples 1-5》 [Manufacturing of Positive Electrode] In Examples 1-5 and Comparative Examples 1-11, the positive electrode was manufactured according to the following procedure. Lithium nickel cobalt manganese composite oxide (Li) was used as the positive electrode active material. １．０ Ni ０．８ Co ０．１ Mn ０．１ O ２ 90 parts by mass of (a substance), 7 parts by mass of acetylene black as a conductive material, and 3 parts by mass of polyvinylidene fluoride (PVdF) as a binder were mixed in an N-methylpyrrolidone solvent using a disperser to form a slurry. This slurry was uniformly applied to both sides of a 15 μm thick aluminum foil, which served as the current collector, and after drying, the density was 3.0 g / cm³. ３ It was pressed in this manner to form the positive electrode.

[0226] [Manufacturing of the Negative Electrode] In all Examples 1-5 and Comparative Examples 1-11, the negative electrode was prepared according to the following procedure. 98 parts by mass of graphite powder was used as the negative electrode active material. 1 part by mass of aqueous dispersion of sodium carboxymethylcellulose (concentration of sodium carboxymethylcellulose 1% by mass) was added as a thickener, and 1 part by mass of aqueous dispersion of styrene-butadiene rubber (concentration of styrene-butadiene rubber 50% by mass) was added as a binder. The mixture was then mixed in a disperser to form a slurry. The obtained slurry was applied to one side of a 10 μm thick copper foil current collector and dried, resulting in a density of 1.5 g / cm³. ３ It was pressed in this manner to form the negative electrode.

[0227] [Preparation of Non-Aqueous Electrolyte] In Examples 1 to 5 and Comparative Examples 1 to 11, a non-aqueous electrolyte was prepared by the following procedure. Under a dry argon atmosphere, a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) (volume ratio EC:EMC:DMC = 3:4:3) was used, and a thoroughly dried LiPF was added as the electrolyte. ６ A non-aqueous electrolyte was prepared by adding 1.2 mol / L of [component name], 1% by mass of vinylene carbonate, and compound (A) or compound (B) in the amounts shown in Tables 1 to 3 below. In Comparative Examples 1 and 3 to 11, compound (A) was not added, so the "Anion content of general formula (1) (wt%)" is shown as "-" in Tables 1 to 3.

[0228] [Manufacturing of Non-Aqueous Electrolyte Secondary Batteries: Comparative Example 1, Comparative Example 2, Comparative Example 8] The positive and negative electrodes obtained above were laminated with a polypropylene three-layer separator (thickness: 16 μm, air permeability: 238 seconds / 100 mL) as the base layer to obtain an electrode group. The obtained electrode group was inserted into a laminate film bag made of aluminum (thickness 40 μm) with both sides coated with a resin layer, so that the terminals of the positive and negative electrodes protruded. Then, each of the non-aqueous electrolytes prepared above was injected into the bag and vacuum sealed to manufacture a pouch-type non-aqueous electrolyte secondary battery.

[0229] [Manufacturing of non-aqueous electrolyte secondary batteries: Comparative Example 3, Comparative Example 9 and Example 1] As a separator, Al dispersed in PAA, which is the binder, is placed on both sides of the three polypropylene layers (16 μm thick) which are the base layer. ２ O ３ A pouch-type non-aqueous electrolyte secondary battery was manufactured in the same manner as in Comparative Examples 1, 2, and 8, except that a separator with an alumina coating layer (each layer thickness: 2.0 μm) was used (total separator thickness: 20 μm, air permeability: 250 seconds / 100 mL).

[0230] [Manufacturing of Non-Aqueous Electrolyte Secondary Batteries: Comparative Examples 4, 10 and 2] A pouch-type non-aqueous electrolyte secondary battery was manufactured in the same manner as Comparative Examples 1, 2 and 8, except that a separator was used in which a polyethylene single layer (thickness 9.0 μm) as a base layer had a coating layer (thickness of each layer: 1.5 μm) made of boehmite as inorganic particles formed on both sides (total separator thickness: 12.0 μm, air permeability: 180 seconds / 100 mL).

[0231] [Manufacturing of Non-Aqueous Electrolyte Secondary Batteries: Comparative Examples 5, 11 and 3] A pouch-type non-aqueous electrolyte secondary battery was manufactured in the same manner as Comparative Examples 1, 2 and 8, except that a separator (total separator thickness 21.0 μm) was used, in which a coating layer (thickness: 4.0 μm) using boehmite as inorganic particles was formed on one side (positive electrode side) of a polypropylene / polyethylene / polypropylene three-layer separator (thickness 17.0 μm) which was the base layer.

[0232] [Manufacturing of Non-Aqueous Electrolyte Secondary Batteries: Comparative Example 6 and Example 4] A pouch-type non-aqueous electrolyte secondary battery was manufactured in the same manner as Comparative Examples 1, 2, and 8, except that a separator (total separator thickness 8.0 μm) was used, in which a coating layer (thickness 3.0 μm) using boehmite as inorganic particles was formed on one side (positive electrode side) of a single layer of polypropylene (thickness 5.0 μm) which was the base layer.

[0233] [Manufacturing of Non-Aqueous Electrolyte Secondary Batteries: Comparative Example 7 and Example 5] A pouch-type non-aqueous electrolyte secondary battery was manufactured in the same manner as Comparative Examples 1, 2 and 8, except that a separator was used in which a single layer of polyethylene (thickness 7.0 μm) as a base layer was coated with boehmite as inorganic particles on both sides (thickness of each layer: 3.0 μm each) (total separator thickness 13.0 μm).

[0234] 《Evaluation of Non-Aqueous Electrolyte Secondary Batteries》 [Initial Conditioning] In a constant temperature bath at 25°C, the non-aqueous electrolyte secondary battery prepared by the above method was charged with a constant current of 0.05C (1C is defined as the current value required to discharge the rated capacity based on the discharge capacity at a 1-hour rate in 1 hour; the same applies hereinafter) until it reached 3.7V, and then discharged with a constant current of 0.2C until it reached 2.8V. Furthermore, after charging with a constant current-constant voltage of 0.2C until it reached 4.1V, the non-aqueous electrolyte secondary battery was stabilized by high-temperature storage at 60°C for 24 hours. After that, initial conditioning was performed by discharging with a constant current of 0.2C until it reached 2.8V at 25°C, then charging with a constant current-constant voltage of 0.2C until it reached a voltage of 4.3V, and finally discharging with a constant current of 0.2C until it reached 2.8V.

[0235] [Gas generation during high-temperature charging and storage] The volume of the non-aqueous electrolyte secondary battery after the initial conditioning described above was measured using Archimedes' principle. The battery was then stored again at 60°C for two weeks to induce high-temperature charging and storage conditions. The volume of the battery was then measured again using Archimedes' principle. The change in battery volume before and after storage was defined as the gas increase after storage (mL), and the relative gas generation (%) of each example and comparative example, with the gas increase after storage of Comparative Example 1 set as 100%, is shown in Tables 1 to 3.

[0236]

[0237]

[0238]

[0239] As can be seen from Tables 1 to 3, the non-aqueous electrolyte secondary batteries of Examples 1 to 5 according to this embodiment showed excellent results in suppressing gas generation during high-temperature charging and storage. On the other hand, Comparative Examples 1, 3 to 7, which did not contain compound (A) containing the anion represented by general formula (1) as a constituent anion in the non-aqueous electrolyte, Comparative Examples 8 to 11, which used compound (B) instead of compound (A), and Comparative Example 2, which contained compound (A) in the non-aqueous electrolyte but used a separator without a coating layer, showed inferior results in suppressing gas generation during high-temperature charging and storage.

[0240] In particular, compared to Comparative Example 3, in Example 1, simply adding compound (A) to the non-aqueous electrolyte reduced the gas increase from 103% to 36%, or about one-third, showing a remarkable effect. Similarly, comparing Comparative Example 4 with Example 2, and Comparative Example 5 with Example 3, it can be seen that the non-aqueous electrolyte secondary battery according to this embodiment reduced the gas increase by about half. Comparing Comparative Example 6 with Example 4, and Comparative Example 7 with Example 5, it can be seen that the non-aqueous electrolyte secondary battery according to this embodiment reduced the gas increase by about 60-80%. Furthermore, comparing Examples 1 to 5, the smaller the thickness ratio expressed as {coat layer thickness on the positive electrode side (μm) / substrate layer thickness (μm)}, the greater the effect of suppressing gas generation during high-temperature charging and storage. On the other hand, in non-aqueous electrolyte secondary batteries using separators without a coating layer, Comparative Example 2 (83%), in which compound (A) was added to the non-aqueous electrolyte, showed some suppression of gas generation compared to Comparative Example 1 (100%, baseline), but the effect was limited. Furthermore, Comparative Examples 8 to 11, which used compound (B) instead of compound (A), resulted in even greater gas generation than Comparative Example 1, which was used as the baseline.

[0241] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2024-193069 filed on November 1, 2024, the contents of which are incorporated herein by reference.

[0242] The non-aqueous electrolyte secondary battery according to this embodiment can be used in various known applications. Specific examples of applications include, for example, notebook computers, pen-input computers, mobile computers, e-book players, mobile phones, portable fax machines, portable copiers, portable printers, portable audio players, small video cameras, headphone stereos, video camcorders, LCD televisions, handheld vacuum cleaners, portable CDs, MiniDiscs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, automobiles, motorcycles, mopeds, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, strobes, cameras, household backup power supplies, business backup power supplies, load leveling power supplies, and natural energy storage power supplies. The non-aqueous electrolyte secondary battery according to this embodiment is particularly suitable for use in automobiles, motorcycles, mopeds, and bicycles, due to its excellent effect in suppressing gas generation during high-temperature charging and storage.

Claims

A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, The aforementioned non-aqueous electrolyte contains an anion represented by the following general formula (1): The separator comprises a base layer and a coating layer, A non-aqueous electrolyte secondary battery having a total thickness of 1.0 to 10.0 μm of the coating layer. (In general formula (1), X represents a sulfur atom or a phosphorus atom, m is 1 or 2, and R １ ~R ４ Each of these independently represents a fluorine atom, a C1-C4 alkyl group, a C1-C4 halogenated alkyl group, or an -OH group. However, when X is a sulfur atom, m is 2 and R ４ (It does not exist, and if X is a phosphorus atom, then m is 1.) 　 As the anion represented by the general formula (1), R in the general formula (1) １ ~R ４ However, each is independently an anion which is a fluorine atom or a trifluoromethyl group, or R in the general formula (1) above. １ ~R ３ However, each is independently a fluorine atom or a trifluoromethyl group, and R ４ A non-aqueous electrolyte secondary battery according to claim 1, comprising an anion in a state where no such anion exists. 　 The non-aqueous electrolyte secondary battery according to claim 1, wherein the anion represented by the general formula (1) is a sulfur atom in the general formula (1). 　 The non-aqueous electrolyte secondary battery according to claim 1, wherein the anion represented by the general formula (1) includes at least one selected from bis(difluorophosphoryl)imide anion, (difluorophosphoryl)(trifluoromethanesulfonyl)imide anion, and (difluorophosphoryl)(fluorosulfonyl)imide anion. 　 The non-aqueous electrolyte secondary battery according to claim 1, wherein the anion represented by the general formula (1) includes a (difluorophosphoryl)(fluorosulfonyl)imide anion. 　 The non-aqueous electrolyte secondary battery according to claim 1, wherein the content of the anion represented by the general formula (1) in the non-aqueous electrolyte is 0.001 to 10% by mass. 　 The non-aqueous electrolyte secondary battery according to claim 1, wherein the non-aqueous electrolyte substantially does not contain succinic anhydride. 　 The non-aqueous electrolyte secondary battery according to claim 1, wherein the total thickness of the coating layer is 1.2 to 6.5 μm. 　 The non-aqueous electrolyte secondary battery according to claim 1, wherein the ratio of the total thickness of the coating layer to the thickness of the substrate layer {total thickness of the coating layer (μm) / thickness of the substrate layer (μm)} is 0.10 to 0.

90. The separator is provided with the coating layer at least on the positive electrode side, The non-aqueous electrolyte secondary battery according to claim 1, wherein the ratio of the thickness of the coating layer on the positive electrode side to the thickness of the substrate layer {thickness of the coating layer on the positive electrode side (μm) / thickness of the substrate layer (μm)} is 0.10 to 0.

70. The non-aqueous electrolyte secondary battery according to claim 1, wherein the coating layer comprises at least one selected from inorganic particles and polymer materials. 　 The non-aqueous electrolyte secondary battery according to claim 11, wherein the coating layer further comprises a binder. 　 A method for manufacturing a non-aqueous electrolyte secondary battery according to any one of claims 1 to 12, As the separator, one comprising a base layer and a coating layer is used. A method for producing a non-aqueous electrolyte secondary battery, comprising the step of dissolving a compound containing an anion represented by the general formula (1) as a constituent anion in a non-aqueous solvent. 　 A vehicle comprising a non-aqueous electrolyte secondary battery according to any one of claims 1 to 12.

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