Nonaqueous electrolyte, nonaqueous electrolyte secondary battery, negative electrode for nonaqueous electrolyte secondary battery, positive electrode for nonaqueous electrolyte secondary battery, and heterocyclic aromatic compound

Abstract

To provide a nonaqueous electrolyte, a negative electrode for a nonaqueous electrolyte secondary battery, a positive electrode for a nonaqueous electrolyte secondary battery, and a heterocyclic aromatic compound, enabling suppression of resistance increase in a nonaqueous electrolyte secondary battery during prolonged storage under high-temperature conditions.SOLUTION: A nonaqueous electrolyte comprising at least one heterocyclic aromatic compound selected from the group consisting of compounds represented by formulae (I-1) to (I-5), the nonaqueous electrolyte enabling suppression of resistance increase in a nonaqueous electrolyte secondary battery during prolonged storage under high-temperature conditions.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a non-aqueous electrolyte, a non-aqueous electrolyte secondary battery, a negative electrode for a non-aqueous electrolyte secondary battery, a positive electrode for a non-aqueous electrolyte secondary battery, and a heterocyclic aromatic compound. [Background technology]

[0002] In recent years, power storage devices such as lithium-ion secondary batteries, which are small, lightweight, and have high output, have become increasingly sophisticated, and as a result, they are increasingly being used not only in small electrical appliances but also in large products such as automobiles. Lithium-ion secondary batteries are required to meet specific requirements regarding various characteristics such as output characteristics and charge / discharge characteristics, but one very important evaluation item is whether or not the output degradation that occurs when stored for a long period of time in a high-temperature environment is minimal.

[0003] Patent Document 1 discloses an invention of a non-aqueous electrolyte containing a combination of lithium trifluoromethanesulfonate (TFMSLi), lithium difluorophosphate (LiDFP), and lithium bis(oxalato)borate (LiBOB), and reports that the use of such a non-aqueous electrolyte reduces the resistance at −10°C after storage at 60°C for 5 days. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 181369 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of one aspect of the present disclosure is to provide a nonaqueous electrolyte, a negative electrode for a nonaqueous electrolyte secondary battery, a positive electrode for a nonaqueous electrolyte secondary battery, and a heterocyclic aromatic compound that can suppress an increase in resistance of a nonaqueous electrolyte secondary battery when stored for a long period of time in a high-temperature environment.An object of another aspect of the present disclosure is to provide a nonaqueous electrolyte secondary battery that suppresses an increase in resistance when stored for a long period of time in a high-temperature environment. [Means for solving the problem]

[0006] As a result of extensive research to solve the above problems, the present inventors have found that by incorporating a nonaqueous electrolyte solution containing a specific heterocyclic aromatic compound into a nonaqueous electrolyte solution or the like, it is possible to suppress an increase in resistance of a nonaqueous electrolyte secondary battery when stored for a long period of time in a high-temperature environment, and have completed the present invention.

[0007] That is, one aspect of the present disclosure includes the following. <1> A non-aqueous electrolyte solution containing at least one heterocyclic aromatic compound selected from the group consisting of a compound represented by the following formula (I-1), a compound represented by the following formula (I-2), a compound represented by the following formula (I-3), a compound represented by the following formula (I-4), and a compound represented by the following formula (I-5).

[0008] [ka]

[0009] In formulas (I-1) to (I-5), Ar represents a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-1), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-2), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-3), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-4), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-5), or an aromatic hydrocarbon group represented by the following formula (Ar-6); M1 +each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion, and x represents 1 or 2.

[0010] [ka]

[0011] (In formula (Ar-1) ~ formula (Ar-6), M1 + each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion, and y represents an integer of 0 to 2. <2> The compound represented by formula (I-1) is at least one heterocyclic aromatic compound selected from the group consisting of a compound represented by formula (I-1-1) below, a compound represented by formula (I-1-2) below, a compound represented by formula (I-1-3) below, a compound represented by formula (I-1-4) below, a compound represented by formula (I-1-5) below, and a compound represented by formula (I-1-6) below. <1> The non-aqueous electrolyte solution according to claim 1.

[0012] [ka]

[0013] (In formulas (I-1-1) to (I-1-6), M1 + each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion, x represents 1 or 2, and y represents an integer of 0 to 2. <3> the total content of the heterocyclic aromatic compounds is 0.01% by mass to 5.0% by mass relative to the total amount of the non-aqueous electrolyte; <1> or <2> The non-aqueous electrolyte solution according to claim 1. <4> The composition further contains at least one compound selected from the group consisting of a difluorophosphate salt represented by the following formula (II-1), a monofluorophosphate salt represented by the following formula (II-2), a salt represented by the following formula (III), a cyclic sulfate compound represented by the following formula (IV), a cyclic sulfonate compound represented by the following formula (V), and a cyclic carbonate compound represented by the following formula (VI): <1> ~ <3> 1. The non-aqueous electrolyte according to any one of the above.

[0014] [ka]

[0015] (In formulas (II-1) and (II-2), M2 + each independently represents an alkali metal ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion. In formula (III), each R3 independently represents a single bond (-) or a divalent hydrocarbon group having 1 to 6 carbon atoms which may contain a halogeno group as a substituent; each Q3 independently represents an oxa group (-O-) or a secondary amino group (-NH-); each X3 independently represents a halogeno group; each Z3 independently represents a boron atom or a phosphorus atom; + represents an alkali metal ion, ammonium ion, imidazolium ion, pyridinium ion, pyrrolidinium ion, or piperidinium ion; h represents 1 or 2 when Z3 is a boron atom, or an integer from 1 to 3 when Z3 is a phosphorus atom; i represents 0 or 2 when Z3 is a boron atom, or 0, 2, or 4 when Z3 is a phosphorus atom. In formula (IV), R 41 represents a group represented by formula (iv-1), a group represented by formula (iv-2), or a divalent hydrocarbon group having 1 to 6 carbon atoms, In formula (iv-1), R 42 represents an oxymethylene group (-OCH2-), an oxyethylene group (-OCH2CH2-), an oxa group (-O-), or a divalent hydrocarbon group having 1 to 6 carbon atoms, In formula (iv-2), R43 represents a hydrocarbon group having 1 to 8 carbon atoms. In formula (V), each R5 independently represents a halogeno group, a fluorocarbon group having 1 to 12 carbon atoms, or a hydrocarbon group having 1 to 12 carbon atoms which may contain at least one functional group selected from the group consisting of a halogeno group and an oxa group (—O—) as a substituent, and j represents an integer of 0 to 3. In formula (VI), each R6 independently represents a halogeno group, a fluorocarbon group having 1 to 12 carbon atoms, or a hydrocarbon group having 1 to 12 carbon atoms which may contain at least one functional group selected from the group consisting of a halogeno group and an oxa group (—O—) as a substituent, and k represents an integer of 0 to 2. <5> A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, a non-aqueous electrolyte, and a separator, The non-aqueous electrolyte is <1> ~ <4> 1. A non-aqueous electrolyte secondary battery comprising the non-aqueous electrolyte according to any one of the above. <6> A negative electrode for a non-aqueous electrolyte secondary battery, comprising: a current collector; and a negative electrode mixture layer formed on the current collector and containing a negative electrode active material, The negative electrode for a non-aqueous electrolyte secondary battery, wherein the negative electrode mixture layer contains at least one heterocyclic aromatic compound selected from the group consisting of a compound represented by the following formula (I-1), a compound represented by the following formula (I-2), a compound represented by the following formula (I-3), a compound represented by the following formula (I-4), and a compound represented by the following formula (I-5).

[0016] [ka]

[0017] In formulas (I-1) to (I-5), Ar represents a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-1), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-2), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-3), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-4), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-5), or an aromatic hydrocarbon group represented by the following formula (Ar-6); M1 +each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion, and x represents 1 or 2.

[0018] [ka]

[0019] (In formula (Ar-1) ~ formula (Ar-6), M1 + each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion, and y represents an integer of 0 to 2. <7> A positive electrode for a non-aqueous electrolyte secondary battery, comprising: a current collector; and a positive electrode mixture layer formed on the current collector and containing a positive electrode active material, The positive electrode for a non-aqueous electrolyte secondary battery, wherein the positive electrode mixture layer contains at least one heterocyclic aromatic compound selected from the group consisting of a compound represented by the following formula (I-1), a compound represented by the following formula (I-2), a compound represented by the following formula (I-3), a compound represented by the following formula (I-4), and a compound represented by the following formula (I-5).

[0020] [ka]

[0021] In formulas (I-1) to (I-5), Ar represents a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-1), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-2), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-3), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-4), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-5), or an aromatic hydrocarbon group represented by the following formula (Ar-6); M1 +each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion, and x represents 1 or 2.

[0022] [ka]

[0023] (In formula (Ar-1) ~ formula (Ar-6), M1 + each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion, and y represents an integer of 0 to 2. <8> A heterocyclic aromatic compound represented by the following formula (I-1-1B) or (I-1-1D):

[0024] [ka] [Effects of the Invention]

[0025] According to one aspect of the present disclosure, there are provided a nonaqueous electrolyte, a negative electrode for a nonaqueous electrolyte secondary battery, a positive electrode for a nonaqueous electrolyte secondary battery, and a heterocyclic aromatic compound, which are capable of suppressing an increase in resistance of a nonaqueous electrolyte secondary battery when stored for a long period of time in a high-temperature environment. Also, according to another aspect of the present disclosure, there is provided a nonaqueous electrolyte secondary battery in which an increase in resistance when stored for a long period of time in a high-temperature environment is suppressed. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a lithium secondary battery precursor according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic cross-sectional view showing a coin-type battery, which is another example of the lithium secondary battery of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0027] In explaining the invention according to the present disclosure, specific examples will be given, but the invention is not limited to the following content as long as it does not deviate from the spirit of the invention according to the present disclosure, and can be modified and implemented as appropriate.

[0028] In the present disclosure, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In the present disclosure, in the numerical ranges described in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with the value shown in the examples. In the present disclosure, when a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified. In the present disclosure, combinations of preferred aspects are more preferred aspects. In the present disclosure, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.

[0029] <Nonaqueous electrolyte> A nonaqueous electrolyte solution according to one embodiment of the present disclosure (hereinafter, sometimes abbreviated as "the nonaqueous electrolyte solution") contains at least one heterocyclic aromatic compound (hereinafter, sometimes abbreviated as "heterocyclic aromatic compound") selected from the group consisting of a compound represented by the following formula (I-1), a compound represented by the following formula (I-2), a compound represented by the following formula (I-3), a compound represented by the following formula (I-4), and a compound represented by the following formula (I-5).

[0030] [ka]

[0031] In formulas (I-1) to (I-5), Ar represents a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-1), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-2), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-3), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-4), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-5), or an aromatic hydrocarbon group represented by the following formula (Ar-6); + each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion; and x represents 1 or 2.

[0032] [ka]

[0033] In formula (Ar-1) ~ formula (Ar-6), M1 + each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion; and y represents an integer of 0 to 2.

[0034] As a result of extensive research into the low-temperature resistance of non-aqueous electrolyte secondary batteries when stored for long periods in a high-temperature environment, the present inventors have found that by incorporating a non-aqueous electrolyte containing the heterocyclic aromatic compound into a non-aqueous electrolyte, etc., it is possible to suppress an increase in the resistance of non-aqueous electrolyte secondary batteries when stored for long periods in a high-temperature environment. The "heterocyclic aromatic compound" and the like will be explained in detail below.

[0035] (heterocyclic aromatic compounds)

[0036] [ka]

[0037] In formulas (I-1) to (I-5), -(COO - M1+ The -Ar group and -N group are inserted into the pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, and triazine ring. This is because the CH group on the ring other than the aza group (-N=) of the pyridine ring, etc., is not inserted into the -(COO - M1 + ) group and -Ar group, - M1 + The substitution position of the -(COO) group and the -Ar group may be, for example, the 2nd, 3rd, 4th, or 5th position of the pyridine ring. In addition, since x is 1 or 2, the pyridine ring etc. is one -(COO - M1 + ) group or two -(COO - M1 + ) group.

[0038] In formulas (I-1) to (I-5), Ar represents "a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-1)," "a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-2)," "a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-3)," "a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-4)," "a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-5)," or "an aromatic hydrocarbon group represented by the following formula (Ar-6)." In formulas (Ar-1) to (Ar-6), the straight lines separated by wavy lines represent single bonds, and the end of the wavy line indicates that the -Ar group in formulas (I-1) to (I-5) is bonded to a pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, or triazine ring. For example, a compound represented by formula (I-1) in which Ar is a heterocyclic aromatic hydrocarbon group represented by formula (Ar-1) has a bipyridine structure in which two pyridine rings are bonded by a single bond. In addition, in the formulas (Ar-1) to (Ar-6), -(COO - M1 + ) group and the single bond separated by the wavy line (bond to the adjacent pyridine ring, etc.) are inserted into the pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, and benzene ring, but this also means that the CH group on the ring other than the aza group (-N=) of the pyridine ring, etc., is -(COO - M1+ ) group and a single bond separated by a wavy line, - M1 + The substitution position of the -(COO) group and the single bond separated by the wavy line may be, for example, any of the 2-, 3-, 4-, and 5-positions on the pyridine ring. In addition, since y is an integer of 0 to 2, the pyridine ring etc. is one -(COO - M1 + ) group or two -(COO - M1 + ) group or substituted by -(COO - M1 + ) group may be unsubstituted.

[0039] [ka]

[0040] M1 + each independently represents an "alkali metal ion," "hydrogen ion," "ammonium ion," "imidazolium ion," "pyridinium ion," "pyrrolidinium ion," or "piperidinium ion," but alkali metal ions and hydrogen ions are preferred, and lithium ions (Li + ) is particularly preferred.

[0041] x represents 1 or 2, preferably 1. y represents an integer of 0 to 2, preferably 1.

[0042] Ar represents "a heterocyclic aromatic hydrocarbon group represented by formula (Ar-1)," "a heterocyclic aromatic hydrocarbon group represented by formula (Ar-2)," "a heterocyclic aromatic hydrocarbon group represented by formula (Ar-3)," "a heterocyclic aromatic hydrocarbon group represented by formula (Ar-4)," "a heterocyclic aromatic hydrocarbon group represented by formula (Ar-5)," or "aromatic hydrocarbon group represented by formula (Ar-6)." However, "a heterocyclic aromatic hydrocarbon group represented by formula (Ar-1)" is particularly preferred. In addition, as the compound represented by formula (I-1) in which Ar is "a heterocyclic aromatic hydrocarbon group represented by formula (Ar-1)," at least one heterocyclic aromatic compound selected from the group consisting of compounds represented by the following formula (I-1-1), compounds represented by the following formula (I-1-2), compounds represented by the following formula (I-1-3), compounds represented by the following formula (I-1-4), compounds represented by the following formula (I-1-5), and compounds represented by the following formula (I-1-6) is preferred.

[0043] [ka]

[0044] In formulas (I-1-1) to (I-1-6), M1 + each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion; x represents 1 or 2; and y represents an integer of 0 to 2.

[0045] Examples of heterocyclic aromatic compounds include compounds represented by the following formula: The present non-aqueous electrolyte may contain two or more types of heterocyclic aromatic compounds.

[0046] [ka]

[0047] The heterocyclic aromatic compound represented by the following formula (I-1-1B) or (I-1-1D) is also one embodiment of the present invention. [ka]

[0048] The heterocyclic aromatic compound represented by formula (I-1-1B) or formula (I-1-1D) can be produced, for example, by ion-exchanging the hydrogen ions of the carboxyl groups of [2,2'-bipyridine]-3,3'-dicarboxylate or [2,2'-bipyridine]-6,6'-dicarboxylate with lithium ions. When ion exchange is performed, the concentration of [2,2'-bipyridine]-3,3'-dicarboxylate or the like relative to the solvent water is typically 0.5 mmol / L to 10 mol / L, with the lower limit preferably being 1 mmol or more, more preferably 1.5 mmol or more, and even more preferably 2 mmol or more, and the upper limit preferably being 8 mol / L or less, more preferably 6 mol / L or less, even more preferably 4 mol / L or less, and particularly preferably 2 mol / L or less. When the concentration of [2,2'-bipyridine]-3,3'-dicarboxylate or the like is within the above range, the heterocyclic aromatic compound represented by Formula (I-1-1B) or Formula (I-1-1D) can be efficiently produced.

[0049] The total content of heterocyclic aromatic compounds in the non-aqueous electrolyte is usually 0.01% by mass or more and 5.0% by mass or less, with the lower limit being preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, and particularly preferably 1.0% by mass or more, and the upper limit being preferably 4.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 2.0% by mass or less, and particularly preferably 1.5% by mass or less, with the total content of these compounds within this range making it easier to reduce the rate of increase in low-temperature resistance of non-aqueous electrolyte secondary batteries when stored for long periods in a high-temperature environment.

[0050] The nonaqueous electrolyte solution is not particularly limited as long as it contains the heterocyclic aromatic compound described above, but it preferably further contains at least one compound selected from the group consisting of a difluorophosphate represented by the following formula (II-1), a monofluorophosphate represented by the following formula (II-2), a salt represented by the following formula (III), a cyclic sulfate compound represented by the following formula (IV), a cyclic sulfonate compound represented by the following formula (V), and a cyclic carbonate compound represented by the following formula (VI). Hereinafter, the "difluorophosphate represented by the formula (II-1)", "monofluorophosphate represented by the formula (II-2)", "salt represented by the formula (III)", "cyclic sulfate compound represented by the formula (IV)", "cyclic sulfonate compound represented by the formula (V)", and "cyclic carbonate compound represented by the formula (VI)" will be described in detail.

[0051] [ka]

[0052] (Difluorophosphate represented by formula (II-1) · Monofluorophosphate represented by formula (II-2))

[0053] [ka]

[0054] In formulas (II-1) and (II-2), M2 + each independently represents an alkali metal ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion.

[0055] M2 + each independently represents an "alkali metal ion," an "ammonium ion," an "imidazolium ion," a "pyridinium ion," a "pyrrolidinium ion," or a "piperidinium ion," but does not represent a lithium ion (Li + ) is particularly preferred.

[0056] Examples of the difluorophosphate represented by formula (II-1) and the monofluorophosphate represented by formula (II-2) include lithium difluorophosphate (LiPOF) represented by the following formula (II-1-1) and lithium monofluorophosphate (LiPOF) represented by the following formula (II-2-1). The nonaqueous electrolyte may contain two or more types of difluorophosphate represented by formula (II-1) and monofluorophosphate represented by formula (II-2).

[0057] [ka]

[0058] The total content of the difluorophosphate represented by formula (II-1) and the monofluorophosphate represented by formula (II-2) in the nonaqueous electrolyte is typically 0.01% by mass or more and 5.0% by mass or less, with the lower limit preferably being 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.3% by mass or more, and particularly preferably 0.5% by mass or more, and the upper limit preferably being 4.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 2.0% by mass or less, and particularly preferably 1.5% by mass or less. When the total content of these compounds is within this range, the rate of increase in low-temperature resistance of a nonaqueous electrolyte secondary battery when stored for a long period of time in a high-temperature environment is easily reduced.

[0059] (Salt represented by formula (III))

[0060] [ka]

[0061] In formula (III), each R3 independently represents a single bond (-) or a divalent hydrocarbon group having 1 to 6 carbon atoms which may contain a halogeno group as a substituent; each Q3 independently represents an oxa group (-O-) or a secondary amino group (-NH-); each X3 independently represents a halogeno group; each Z3 independently represents a boron atom or a phosphorus atom; + represents an alkali metal ion, ammonium ion, imidazolium ion, pyridinium ion, pyrrolidinium ion, or piperidinium ion; h represents 1 or 2 when Z3 is a boron atom, or an integer from 1 to 3 when Z3 is a phosphorus atom; i represents 0 or 2 when Z3 is a boron atom, or 0, 2, or 4 when Z3 is a phosphorus atom.

[0062] Each R3 independently represents a "single bond (-)" or a "divalent hydrocarbon group having 1 to 6 carbon atoms, which may contain a halogeno group as a substituent." When R3 is a "single bond (-)," this means that two carbonyl groups (>C=O) adjacent to R3 are directly bonded. Furthermore, a "divalent hydrocarbon group" refers to a hydrocarbon group having two bonding positions, and is not limited to aliphatic hydrocarbon groups having a linear structure, but may also be a group having at least one structure selected from the group consisting of a branched structure, a cyclic structure, and a carbon-carbon unsaturated bond structure (a carbon-carbon double bond structure and a carbon-carbon triple bond structure), or may also be an aromatic hydrocarbon group. In other words, alkylene groups, alkenylene groups, alkynylene groups, arylene groups, etc. are all included in the "divalent hydrocarbon group." Furthermore, "may contain a halogeno group as a substituent" means that the hydrogen atom of the hydrocarbon group may be substituted with a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), an iodo group (-I), etc.

[0063] The hydrocarbon group of R3 preferably has 5 or less carbon atoms, more preferably 4 or less, even more preferably 3 or less, and particularly preferably 2 or less.

[0064] Examples of R3 include a single bond (-), a methylene group (-CH2-), an ethylene group (-CH2CH2-), and an n-propylene group (-CH2CH2CH2-), with a single bond (-) and a methylene group (-CH2-) being particularly preferred.

[0065] Each Q3 independently represents an "oxa group (-O-)" or a "secondary amino group (-NH-)". When two Q3 are "oxa groups (-O-)" and R3 is "a single bond (-)", this means that an oxalate ion (CO4 2- ) is a multidentate ligand, forming an oxalato complex.

[0066] As Q3, an oxa group (—O—) is particularly preferred.

[0067] Each X3 independently represents a "halogeno group", and is particularly preferably a fluoro group (-F).

[0068] Z3 represents a "boron atom" or a "phosphorus atom", but a boron atom is particularly preferred from the viewpoint of suppressing an increase in the resistance of the nonaqueous electrolyte secondary battery when stored for a long period of time in a high temperature environment.

[0069] M3 + represents an "alkali metal ion," "ammonium ion," "imidazolium ion," "pyridinium ion," "pyrrolidinium ion," or "piperidinium ion," but does not represent a lithium ion (Li + ) is particularly preferred.

[0070] h represents 1 or 2 when Z3 is a boron atom, and an integer from 1 to 3 when Z3 is a phosphorus atom; i represents 0 or 2 when Z3 is a boron atom, and 0, 2, or 4 when Z3 is a phosphorus atom; however, it is particularly preferred that h is 2 and i is 0 when Z3 is a boron atom.

[0071] Examples of the salt represented by formula (III) include lithium bis(oxalato)borate (LiBOB) represented by the following formula (III-1-1), lithium difluorooxalatoborate (LiDFOB) represented by the following formula (III-1-2), lithium difluorobis(oxalato)phosphate (LiDFBOP) represented by the following formula (III-2-1), and lithium tetrafluorooxalatophosphate (LiTFOP) represented by the following formula (III-2-2). The nonaqueous electrolyte may contain two or more types of salt represented by formula (III).

[0072] [ka]

[0073] The total content of the salt represented by formula (III) in the nonaqueous electrolyte is typically 0.01% by mass or more and 5.0% by mass or less, relative to the total amount of the nonaqueous electrolyte (when the total amount of the nonaqueous electrolyte is taken as 100% by mass), with the lower limit preferably being 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.3% by mass or more, and particularly preferably 0.5% by mass or more, and the upper limit preferably being 4.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 2.0% by mass or less, and particularly preferably 1.5% by mass or less. When the total content of these compounds is within this range, the rate of increase in low-temperature resistance of a nonaqueous electrolyte secondary battery when stored for a long period of time in a high-temperature environment is likely to be reduced.

[0074] (Cyclic sulfate compound represented by formula (VI))

[0075] [ka]

[0076] In formula (IV), R 41 represents a group represented by formula (iv-1), a group represented by formula (iv-2), or a divalent hydrocarbon group having 1 to 6 carbon atoms, and in formula (iv-1), R 42represents an oxymethylene group (-OCH2-), an oxyethylene group (-OCH2CH2-), an oxa group (-O-), or a divalent hydrocarbon group having 1 to 6 carbon atoms, and in formula (iv-2), R 43 represents a hydrocarbon group having 1 to 8 carbon atoms.

[0077] R 41 represents "a group represented by formula (vi-1)", "a group represented by formula (vi-2)", or "a divalent hydrocarbon group having 1 to 6 carbon atoms", and the "divalent hydrocarbon group" has the same meaning as in the case of R3.

[0078] R 41 When is a hydrocarbon group, the number of carbon atoms is preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less.

[0079] The wavy lines in formula (iv-1) and formula (iv-2) indicate that their ends are bonded to the two oxygen atoms (—O—) in formula (IV) to form a cyclic sulfate ester structure. 42 represents an "oxymethylene group (-OCH2-)", an "oxyethylene group (-OCH2CH2-)", an "oxa group (-O-)", or a "divalent hydrocarbon group having 1 to 6 carbon atoms", and the "divalent hydrocarbon group" has the same meaning as in the case of R3. 42 is an oxymethylene group (-OCH2-), an oxyethylene group (-OCH2CH2-), or an oxa group (-O-), means that the oxa group is bonded to the sulfur atom (-S(=O)2O-) in formula (iv-1) to form a cyclic sulfate ester structure.

[0080] R 42 As the alkyl group, an oxymethylene group (-OCH2-) and an oxyethylene group (-OCH2CH2-) are particularly preferred.

[0081] R 43represents a "hydrocarbon group having 1 to 8 carbon atoms," and includes methyl group (-CH3), ethyl group (-CH2CH3), vinyl group (-CH=CH2), n-propyl group (-CH2CH2CH3), isopropyl group (-CH(CH3)2), n-butyl group (-CH2CH2CH2CH3), s-butyl group (-CH2CH(CH3)2), isobutyl group (-CH2CH(CH3)2), t-butyl group (-C(CH3)3), hexyl group (-CH2CH2CH2CH2CH2CH2CH3), cyclohexyl group (-CH6H 11 ), and a phenyl group (-C6H5), and an n-butyl group (-CH2CH2CH2CH3) and a hydrogen atom (-H) are particularly preferred.

[0082] Examples of the cyclic sulfate ester compound represented by formula (IV) include a cyclic sulfate ester compound represented by the following formula (IV-1-1), a cyclic sulfate ester compound represented by the following formula (IV-1-2), and a cyclic sulfate ester compound represented by the following formula (IV-1-3).The nonaqueous electrolyte solution may contain two or more types of cyclic sulfate ester compounds represented by formula (IV).

[0083] [ka]

[0084] The total content of the cyclic sulfate ester compounds represented by formula (IV) in the nonaqueous electrolyte is typically 0.01% by mass or more and 5.0% by mass or less, with the lower limit being preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.3% by mass or more, and particularly preferably 0.5% by mass or more, and the upper limit being preferably 4.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 2.0% by mass or less, and particularly preferably 1.5% by mass or less, relative to the total amount of the nonaqueous electrolyte (assuming the total amount of the nonaqueous electrolyte is 100% by mass). When the total content of these compounds is within this range, the rate of increase in low-temperature resistance of the nonaqueous electrolyte secondary battery when stored for a long period of time in a high-temperature environment is likely to be reduced.

[0085] (Cyclic sulfonate compound represented by formula (V))

[0086] [ka]

[0087] In formula (V), each R5 independently represents a halogeno group, a fluorocarbon group having 1 to 12 carbon atoms, or a hydrocarbon group having 1 to 12 carbon atoms which may contain at least one functional group selected from the group consisting of a halogeno group and an oxa group (—O—) as a substituent, and j represents an integer of 0 to 3.

[0088] The double line consisting of a solid line and a dotted line in formula (V) means a single bond (-) or a double bond (=).

[0089] Each R5 independently represents a "halogeno group," a "carbon fluorocarbon group having 1 to 12 carbon atoms," or a "hydrocarbon group having 1 to 12 carbon atoms which may contain, as a substituent, at least one functional group selected from the group consisting of a halogeno group and an oxa group (-O-)." A "carbon fluorocarbon group" refers to a group in which all hydrogen atoms of a hydrocarbon group have been substituted with fluorine atoms. A "carbon fluorocarbon group" is also called a "hydrocarbon fluorocarbon group" or a "fluorocarbon group," and is a concept that includes perfluoroalkyl groups. In addition, the carbon fluorocarbon group is not limited to a linear structure, but may also be a branched structure, a cyclic structure, or a carbon-carbon unsaturated bond structure (a carbon-carbon double bond structure and a carbon-carbon triple bond structure). Furthermore, the "hydrocarbon group" is not limited to an aliphatic hydrocarbon group having a linear structure, but may also be a hydrocarbon group having at least one structure selected from the group consisting of a branched structure, a cyclic structure, and a carbon-carbon unsaturated bond structure (a carbon-carbon double bond structure and a carbon-carbon triple bond structure). Furthermore, since the number of these structures is not limited, (acyclic) aliphatic hydrocarbon groups, monocyclic aliphatic hydrocarbon groups, polycyclic aliphatic hydrocarbon groups, monocyclic aromatic hydrocarbon groups, and polycyclic aromatic hydrocarbon groups are all included in the "hydrocarbon group." Naturally, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, and the like are also included in the "hydrocarbon group." Furthermore, the phrase "may contain at least one functional group selected from the group consisting of a halogeno group and an oxa group (-O-) as a substituent" means that a hydrogen atom of the hydrocarbon group may be substituted with a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), an iodo group (-I), or the like, and further, a carbon atom of the hydrocarbon group may be substituted with an oxa group (-O-).

[0090] When R5 is a fluorocarbon group, the number of carbon atoms is preferably 10 or less, more preferably 8 or less, even more preferably 6 or less, and particularly preferably 4 or less. When R5 is a hydrocarbon group, the number of carbon atoms is preferably 10 or less, more preferably 8 or less, even more preferably 6 or less, and particularly preferably 4 or less.

[0091] R5 is a fluoro group (-F), trifluoromethyl group (-CF3), pentafluoroethyl group (-C2F5), n-heptafluoropropyl group (-C3F7), methyl group (-CH3), ethyl group (-CH2CH3), vinyl group (-CH=CH2), n-propyl group (-CH2CH2CH3), isopropyl group (-CH(CH3)2), n-butyl group (-CH2CH2CH2CH3), s-butyl group (-CH2CH(CH3)2), isobutyl group (-CH2CH(CH3)2), t-butyl group (-C(CH3)3), hexyl group (-CH2CH2CH2CH2CH2CH2CH3), cyclohexyl group (-CH6H 11 ), a phenyl group (-C6H5), a benzyl group (-CH2C6H5), a trifluoromethoxymethyl group (-CH2OCF3), etc., with a hydrogen atom (-H), a fluoro group (-F), a trifluoromethyl group (-CF3), a pentafluoroethyl group (-C2F5), and an n-heptafluoropropyl group (-C3F7) being particularly preferred.

[0092] j represents an integer of 0 to 3, with 0 being preferred.

[0093] Examples of the cyclic sulfonate compound represented by formula (V) include 1,3-propene sultone (PRS) represented by the following formula (V-1-1) and 1,3-propane sultone (PS) represented by the following formula (V-1-2). The nonaqueous electrolyte may contain two or more types of cyclic sulfonate compounds represented by formula (V).

[0094] [ka]

[0095] The total content of the cyclic sulfonate ester compounds represented by formula (V) in the non-aqueous electrolyte is typically 0.01% by mass or more and 5.0% by mass or less, with the lower limit being preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.3% by mass or more, and particularly preferably 0.5% by mass or more, and the upper limit being preferably 4.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 2.0% by mass or less, and particularly preferably 1.5% by mass or less, relative to the total amount of the non-aqueous electrolyte (when the total amount of the non-aqueous electrolyte is taken as 100% by mass). When the total content of these compounds is within this range, the rate of increase in the low-temperature resistance of the non-aqueous electrolyte secondary battery when stored for a long period of time in a high-temperature environment is likely to be reduced.

[0096] (Cyclic carbonate compound represented by formula (VI))

[0097] [ka]

[0098] In formula (VI), each R6 independently represents a halogeno group, a fluorocarbon group having 1 to 12 carbon atoms, or a hydrocarbon group having 1 to 12 carbon atoms which may contain at least one functional group selected from the group consisting of a halogeno group and an oxa group (—O—) as a substituent, and k represents an integer of 0 to 2.

[0099] R6 each independently represents a "halogeno group," a "carbon fluorocarbon group," or a "carbon hydrocarbon group which may contain, as a substituent, at least one functional group selected from the group consisting of a halogeno group and an oxa group (-O-)," and the "carbon fluorocarbon group" and the like have the same meanings as those of R5.

[0100] When R6 is a fluorocarbon group, the number of carbon atoms is preferably 10 or less, more preferably 8 or less, even more preferably 6 or less, and particularly preferably 4 or less. When R6 is a hydrocarbon group, the number of carbon atoms is preferably 10 or less, more preferably 8 or less, even more preferably 6 or less, and particularly preferably 4 or less.

[0101] R6 is a fluoro group (-F), trifluoromethyl group (-CF3), pentafluoroethyl group (-C2F5), n-heptafluoropropyl group (-C3F7), methyl group (-CH3), ethyl group (-CH2CH3), vinyl group (-CH=CH2), n-propyl group (-CH2CH2CH3), isopropyl group (-CH(CH3)2), n-butyl group (-CH2CH2CH2CH3), s-butyl group (-CH2CH(CH3)2), isobutyl group (-CH2CH(CH3)2), t-butyl group (-C(CH3)3), hexyl group (-CH2CH2CH2CH2CH2CH2CH3), cyclohexyl group (-CH6H 11 ), a phenyl group (-C6H5), a benzyl group (-CH2C6H5), a trifluoromethoxymethyl group (-CH2OCF3), etc., with a hydrogen atom (-H), a fluoro group (-F), a trifluoromethyl group (-CF3), a pentafluoroethyl group (-C2F5), and an n-heptafluoropropyl group (-C3F7) being particularly preferred.

[0102] k represents an integer of 0 to 2, with 0 being preferred.

[0103] Examples of the cyclic carbonate compound represented by formula (VI) include vinylene carbonate (VC) represented by the following formula (VI-1-1), formula (VI-1-2), or formula (VI-1-3). The nonaqueous electrolyte may contain two or more types of cyclic carbonate compounds represented by formula (VI).

[0104] [ka]

[0105] The total content of the cyclic carbonate compounds represented by formula (VI) in the non-aqueous electrolyte is typically 0.01% by mass or more and 5.0% by mass or less, with the lower limit being preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.3% by mass or more, and particularly preferably 0.5% by mass or more, and the upper limit being preferably 4.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 2.0% by mass or less, and particularly preferably 1.5% by mass or less, relative to the total amount of the non-aqueous electrolyte (assuming the total amount of the non-aqueous electrolyte is 100% by mass). When the total content of these compounds is within this range, the rate of increase in low-temperature resistance of the non-aqueous electrolyte secondary battery when stored for a long period of time in a high-temperature environment is easily reduced.

[0106] (non-aqueous solvent) The non-aqueous electrolyte generally contains a non-aqueous solvent (excluding the cyclic carbonate compound represented by formula (VI); hereinafter, simply referred to as "non-aqueous solvent"). As the non-aqueous solvent, various known ones can be appropriately selected. The non-aqueous solvent may be one kind or two or more kinds.

[0107] Examples of non-aqueous solvents include chain carbonates, fluorine-containing chain carbonates, aliphatic carboxylic acid esters, fluorine-containing aliphatic carboxylic acid esters, γ-lactones, fluorine-containing γ-lactones, cyclic ethers, fluorine-containing cyclic ethers, chain ethers, fluorine-containing chain ethers, nitriles, amides, lactams, nitromethane, nitroethane, sulfolane, trimethyl phosphate, dimethyl sulfoxide, and dimethyl sulfoxide phosphate. Examples of chain carbonates include dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), and dipropyl carbonate (DPC). Examples of aliphatic carboxylic acid esters include methyl formate, methyl acetate, methyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethylbutyrate, ethyl formate, ethyl acetate, ethyl propionate, ethyl butyrate, ethyl isobutyrate, and ethyl trimethylbutyrate. Examples of γ-lactones include γ-butyrolactone and γ-valerolactone. Examples of cyclic ethers include tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, and 1,4-dioxane. Examples of chain ethers include 1,2-ethoxyethane (DEE), ethoxymethoxyethane (EME), diethyl ether, 1,2-dimethoxyethane, and 1,2-dibutoxyethane. Examples of nitriles include acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, and 3-methoxypropionitrile. Examples of amides include N,N-dimethylformamide. Examples of lactams include N-methylpyrrolidinone, N-methyloxazolidinone, and N,N'-dimethylimidazolidinone.

[0108] The non-aqueous solvent preferably contains at least one selected from the group consisting of chain carbonates and fluorine-containing chain carbonates. In this case, the total proportion of the chain carbonates and fluorine-containing chain carbonates is preferably 50% by mass or more and 100% by mass or less, more preferably 60% by mass or more and 100% by mass or less, and even more preferably 80% by mass or more and 100% by mass or less, based on the total amount of the non-aqueous solvent.

[0109] The upper limit of the content of the nonaqueous solvent is preferably 99 mass %, more preferably 97 mass %, and even more preferably 90 mass %, relative to the total amount of the nonaqueous electrolyte. The lower limit of the content of the nonaqueous solvent is preferably 60 mass % or more, more preferably 70 mass % or more, and even more preferably 80 mass %, relative to the total amount of the nonaqueous electrolyte.

[0110] The intrinsic viscosity of the non-aqueous solvent is preferably 10.0 mPa·s or less at 25° C., from the viewpoint of further improving the dissociation property of the electrolyte and the mobility of ions.

[0111] (electrolyte) The non-aqueous electrolyte generally contains an electrolyte.

[0112] The electrolyte preferably contains at least one of a fluorine-containing lithium salt (hereinafter sometimes referred to as a "fluorine-containing lithium salt") and a fluorine-free lithium salt.

[0113] Examples of the fluorine-containing lithium salt include inorganic acid anion salts and organic acid anion salts. Examples of inorganic acid anion salts include lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), and lithium hexafluorotantalate (LiTaF6). Examples of organic acid anion salts include lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethanesulfonyl)imide (Li(CF3SO2)2N), and lithium bis(pentafluoroethanesulfonyl)imide (Li(C2F5SO2)2N). Among these, lithium hexafluorophosphate (LiPF6) is more preferable as the fluorine-containing lithium salt.

[0114] Fluorine-free lithium salts include lithium perchlorate (LiClO4), lithium tetrachloroaluminate (LiAlCl4), and lithium decachlorodecaborate (Li2B 10 Cl 10) etc.

[0115] When the electrolyte contains a fluorine-containing lithium salt, the content of the fluorine-containing lithium salt is preferably 50% by mass or more and 100% by mass or less, more preferably 60% by mass or more and 100% by mass or less, and even more preferably 80% by mass or more and 100% by mass or less, based on the total amount of the electrolyte. When the fluorine-containing lithium salt contains lithium hexafluorophosphate (LiPF6), the content of lithium hexafluorophosphate (LiPF6) is preferably 50% by mass or more and 100% by mass or less, more preferably 60% by mass or more and 100% by mass or less, and even more preferably 80% by mass or more and 100% by mass or less, based on the total amount of the electrolyte.

[0116] When the non-aqueous electrolyte contains an electrolyte, the concentration of the electrolyte in the non-aqueous electrolyte is preferably 0.1 mol / L or more and 3 mol / L or less, and more preferably 0.5 mol / L or more and 2 mol / L or less.

[0117] When the non-aqueous electrolyte contains lithium hexafluorophosphate (LiPF6), the concentration of lithium hexafluorophosphate (LiPF6) in the non-aqueous electrolyte is preferably 0.1 mol / L or more and 3 mol / L or less, more preferably 0.5 mol / L or more and 2 mol / L or less.

[0118] <Nonaqueous electrolyte secondary battery> A nonaqueous electrolyte secondary battery according to another embodiment of the present invention is a nonaqueous electrolyte secondary battery including a "positive electrode," a "negative electrode," a "nonaqueous electrolyte," and a "separator." The "positive electrode," "negative electrode," "separator," etc. will be described in detail below.

[0119] (positive electrode) Typically, a positive electrode can be produced by dispersing a positive electrode active material, a binder, and optionally a conductive additive and a thickener in a solvent to form a slurry, which is then applied to a current collector, dried, and compressed to form a positive electrode composite layer (also referred to as a "positive electrode active material layer") on the current collector. Another aspect of the present invention is a positive electrode for a non-aqueous electrolyte secondary battery, which includes a current collector and a positive electrode composite layer formed on the current collector and containing a positive electrode active material, wherein the positive electrode composite layer contains at least one heterocyclic aromatic compound selected from the group consisting of the compounds represented by the aforementioned formulas (I-1), (I-2), (I-3), (I-4), and (I-5).

[0120] The positive electrode active material is transition metal oxides or sulfides such as MoS2, TiS2, MnO2, V2O5; LiCoO2, LiMnO2, LiMn2O4, LiNiO2, LiNi X Co (1-X) O2(0 <X<1)、LiNi x Co y Mn z O2 (x, y, and z are each independently greater than 0 and less than 1.00, and the sum of x, y, and z is 0.99 to 1.00) (so-called "NCM"; for example, LiNi 0.33 Co 0.33 Mn 0.33 O2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2) and other composite oxides of transition metals; Li t Ni 1-x-y Co x Al yO2 (where t is 0.95 or more and 1.15 or less, x is 0 or more and 0.3 or less, y is 0.1 or more and 0.2 or less, and the sum of x and y is less than 0.5.) (so-called "NCA"; for example, LiNi 0.8 Co 0.15 Al 0.05 O2) and other composite oxides composed of lithium, transition metals, and typical metals; Conductive polymer materials such as polyaniline, polythiophene, polypyrrole, polyacetylene, polyacene, dimercaptothiadiazole, and polyaniline composites; Lithium metal phosphates such as lithium iron phosphate (LiFePO4), lithium manganese phosphate (LiMnPO4), lithium manganese iron phosphate (LiMn x Fe 1-x PO4; 0 < x < 1), lithium cobalt phosphate (LiCoPO4), lithium nickel phosphate (LiNiPO4), etc.; etc. can be mentioned.

[0121] Examples of the binder for the positive electrode include polyvinylidene fluoride, etc. Examples of the conductive aid for the positive electrode include carbon black (e.g., acetylene black), amorphous whiskers, graphite, etc. Examples of the thickener for the positive electrode include carboxymethyl cellulose, etc. Also, examples of the solvent for the slurry for forming the positive electrode include organic solvents such as N-methylpyrrolidone.

[0122] The total content of the positive electrode active material in the positive electrode mixture layer is usually 70% to 97% by mass, preferably 75% or more and preferably 95% or less when the total content of the positive electrode mixture layer is 100% by mass.

[0123] The total content of heterocyclic aromatic compounds in the positive electrode mixture layer is typically 0.01% by mass or more and 5.0% by mass, with the lower limit being preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, and particularly preferably 1.0% by mass or more, and the upper limit being preferably 4.0% by mass or less, more preferably 3.0% by mass or less, and even more preferably 2.0% by mass or less, when the total content in the positive electrode mixture layer is taken as 100% by mass.

[0124] Examples of materials for the current collector of the positive electrode include aluminum, aluminum alloy, stainless steel, nickel, titanium, tantalum, carbon cloth, and carbon paper.

[0125] (Negative electrode) A typical negative electrode can be produced by dispersing a negative electrode active material, a binder, and optionally a conductive additive and a thickener in a solvent to form a slurry, which is then applied to a current collector, dried, and compressed to form a negative electrode composite layer (also referred to as a "negative electrode active material layer") on the current collector. Another aspect of the present invention is a negative electrode for a non-aqueous electrolyte secondary battery, which includes a current collector and a negative electrode composite layer formed on the current collector and containing a negative electrode active material, wherein the negative electrode composite layer contains at least one heterocyclic aromatic compound selected from the group consisting of the compounds represented by the aforementioned formulas (I-1), (I-2), (I-3), (I-4), and (I-5).

[0126] The negative electrode active material may be classified into (1) carbon and carbon compounds that can be doped / dedoped with lithium ions, (2) metals and alloys that can be alloyed with lithium, and (3) oxides, nitrides, and carbides that can be doped / dedoped with lithium ions. When the negative electrode active material is silicon, a particulate (powder) type of silicon or compound is usually used. The negative electrode active material is not limited to one type, and two or more types may be mixed together.

[0127] The negative electrode active material preferably contains carbon particles and at least one selected from the group consisting of silicon particles, silicon oxide particles, and silicon carbide particles. Examples of carbon particles include graphite (natural graphite, artificial graphite) particles, carbon black particles, activated carbon particles, and amorphous carbon particles. Examples of artificial graphite include graphitized MCMB and graphitized MCF. Examples of amorphous carbon materials include hard carbon, coke, mesocarbon microbeads (MCMB) fired at 1500°C or less, and mesophase pitch carbon fiber (MCF).

[0128] When the element or compound serving as the negative electrode active material is in the form of particles (powder), specific shapes include fibrous, spherical, potato-like, and flake-like shapes.

[0129] When the negative electrode active material contains particles of simple carbon, the median diameter D50 of the simple carbon is usually 1 μm to 30 μm, with the lower limit preferably being 10 μm or more, more preferably 15 μm or more, and the upper limit preferably being 25 μm or less, more preferably 20 μm or less.

[0130] When the negative electrode active material contains carbon particles, the BET specific surface area of ​​the carbon particles is usually 1.0 m 2 / g~5.0m 2 / g, and the lower limit is preferably 2.0m 2 / g or more, more preferably 3.0m 2 / g or more, and the upper limit is preferably 4.5m 2 / g or less, more preferably 4.0m 2 / g or less.

[0131] Silicon oxide is SiO x where x is a variable, i.e., the content of oxygen atoms in silicon oxide is not particularly limited, but x is usually 0≦x<2, the lower limit is preferably 0.2 or more, more preferably 0.4 or more, and even more preferably 0.6 or more, and the upper limit is preferably 1.8 or less, more preferably 1.6 or less, and even more preferably 1.4 or less.

[0132] The median diameter D50 of the silicon particles, silicon oxide particles, or silicon carbide particles is usually 0.5 μm to 20 μm, with the lower limit preferably being 1.0 μm or more, more preferably 3.0 μm or more, and the upper limit preferably being 15 μm or less, more preferably 10 μm or less.

[0133] The BET specific surface area of ​​silicon particles, silicon oxide particles, or silicon carbide particles is usually 1.0 m 2 / g~5.0m 2 / g, and the lower limit is preferably 1.5m 2 / g or more, more preferably 2.0m 2 / g or more, and the upper limit is preferably 4.5m 2 / g or less, more preferably 4.0m 2 / g or less.

[0134] When the negative electrode active material contains carbon particles and at least one selected from the group consisting of silicon particles, silicon oxide particles, and silicon carbide particles, the total mass of the silicon particles, silicon oxide particles, and silicon carbide particles in the negative electrode active material is usually 1% by mass to 20% by mass, when the total mass of the entire negative electrode active material is taken as 100% by mass. The lower limit is preferably 3% by mass or more, more preferably 5% by mass or more, and the upper limit is preferably 18% by mass or less, more preferably 15% by mass or less.

[0135] When the negative electrode active material contains carbon particles and at least one selected from the group consisting of silicon particles, silicon oxide particles, and silicon carbide particles, the total mass of the carbon particles in the negative electrode active material is typically 70% to 99% by mass, with the total mass of the entire negative electrode active material being 100% by mass, but the lower limit is preferably 80% by mass or more, more preferably 85% by mass or more, and the upper limit is preferably 95% by mass or less, more preferably 90% by mass or less. When the total mass of the silicon particles and the like is within this range, it becomes easier to ensure a balance between the energy density and capacity retention rate of the lithium-ion secondary battery.

[0136] The total content of the negative electrode active material in the negative electrode mixture layer is usually 70% by mass to 99.5% by mass when the entire negative electrode mixture layer is taken as 100% by mass, but the lower limit is preferably 75% by mass or more and the upper limit is preferably 99% by mass or less.

[0137] The total content of heterocyclic aromatic compounds in the negative electrode composite layer is usually 0.01% by mass or more and 5.0% by mass, with the lower limit being preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, and particularly preferably 1.0% by mass or more, and the upper limit being preferably 4.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 2.0% by mass or less, and particularly preferably 1.5% by mass or less, when the total content in the negative electrode composite layer is taken as 100% by mass.

[0138] Examples of binders for the negative electrode include styrene-butadiene rubber (SBR). The total content of the binder copolymer in the negative electrode mixture layer is usually 0.1% by mass to 5% by mass when the entire negative electrode mixture layer is taken as 100% by mass, but the lower limit is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and the upper limit is preferably 3% by mass or less, more preferably 2% by mass or less.

[0139] The negative electrode mixture layer preferably further contains a conductive additive such as carbon black (for example, acetylene black), carbon nanotubes, amorphous whiskers, and graphite.

[0140] The total content of the conductive additive in the negative electrode composite layer is usually 0.01% by mass to 3% by mass when the entire negative electrode composite layer is taken as 100% by mass. The lower limit is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and the upper limit is preferably 2% by mass or less, more preferably 1% by mass or less.

[0141] The negative electrode mixture layer preferably further contains a thickener. By including a thickener, it becomes easier to adjust the viscosity of the slurry, thereby improving productivity. Examples of thickeners for the negative electrode include cellulose derivatives such as carboxymethyl cellulose (CMC), carboxyethyl cellulose, and hydroxyethyl cellulose, polyoxyethylene and its modified products, polyvinyl alcohol and its modified products, and polysaccharides.

[0142] The total content of the thickener in the negative electrode mixture layer is usually 0.1% by mass to 5% by mass when the entire negative electrode mixture layer is taken as 100% by mass. The lower limit is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and the upper limit is preferably 3% by mass or less, more preferably 2% by mass or less.

[0143] The slurry may contain a solvent, such as water, acetonitrile, N-methylpyrrolidone, acetylpyridine, cyclopentanone, dimethylformamide, dimethyl sulfoxide, methylformamide, methyl ethyl ketone, furfural, or ethylenediamine. The solvent may be a mixed solvent of the above-mentioned solvents.

[0144] Examples of materials for the current collector of the negative electrode include copper, nickel, stainless steel, and nickel-plated steel.

[0145] <Separator> The nonaqueous electrolyte secondary battery according to one embodiment of the present invention is a nonaqueous electrolyte secondary battery comprising a "positive electrode," a "negative electrode," a "nonaqueous electrolyte," and a "separator." The separator may be a porous resin flat plate. Materials for the porous resin flat plate include resins and nonwoven fabrics containing such resins. Examples of resins include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polyester, cellulose, and polyamide. In particular, the separator is preferably a porous resin sheet having a single layer or a multilayer structure. The porous resin sheet is mainly made of one or more polyolefin resins. The thickness of the separator is preferably 5 μm or more and 30 μm or less. The separator is preferably disposed between the positive electrode and the negative electrode.

[0146] <Case> The shape of the case is not particularly limited and may be appropriately selected depending on the intended use of the lithium ion secondary battery precursor of the present disclosure. Examples of the case include a case including a laminate film, and a case consisting of a battery can and a battery can lid.

[0147] <Specific examples of lithium-ion secondary battery precursors> FIG. 1 is a schematic cross-sectional view showing a laminated lithium ion secondary battery precursor, which is an example of the lithium ion secondary battery precursor of the present disclosure.

[0148] As shown in FIG. 1, a lithium ion secondary battery precursor 1 is a laminated type battery precursor. Specifically, in the lithium ion secondary battery precursor 1, the battery element 10 is enclosed inside an exterior body 30. The exterior body 30 is formed of a laminate film. A positive electrode lead 21 and a negative electrode lead 22 are attached to the battery element 10. The positive electrode lead 21 and the negative electrode lead 22 are led out in opposite directions, from the inside to the outside of the exterior body 30.

[0149] As shown in FIG. 1 , battery element 10 is formed by laminating positive electrode 11, separator 13, and negative electrode 12. Positive electrode 11 has positive electrode composite layer 11B formed on both main surfaces of positive electrode current collector 11A. Negative electrode 12 has negative electrode composite layer 12B formed on both main surfaces of negative electrode current collector 12A. Positive electrode composite layer 11B formed on one main surface of positive electrode current collector 11A of positive electrode 11 and negative electrode composite layer 12B formed on one main surface of negative electrode current collector 12A of negative electrode 12 adjacent to positive electrode 11 face each other with separator 13 interposed therebetween.

[0150] The nonaqueous electrolyte solution of the present disclosure is poured into the interior of the exterior housing 30 of the lithium ion secondary battery precursor 1. The nonaqueous electrolyte solution of the present disclosure permeates the positive electrode composite layer 11B, the separator 13, and the negative electrode composite layer 12B. In the lithium ion secondary battery precursor 1, one unit cell layer 14 is formed by the adjacent positive electrode composite layer 11B, the separator 13, and the negative electrode composite layer 12B. Note that the positive electrode and the negative electrode may each have an active material layer formed on one side of the respective current collectors.

[0151] Although the lithium ion secondary battery precursor 1 is a laminated type lithium ion secondary battery precursor, the lithium ion secondary battery precursor of the present disclosure is not limited thereto and may be, for example, a wound type lithium ion secondary battery precursor. A wound type lithium ion secondary battery precursor is formed by stacking a positive electrode, a separator, a negative electrode, and a separator in this order and winding them into a layered configuration. Wound type lithium ion secondary battery precursors include cylindrical type lithium ion secondary battery precursors and prismatic type lithium ion secondary battery precursors.

[0152] 1 , in the lithium-ion secondary battery precursor 1, the directions in which the positive electrode lead and the negative electrode lead each protrude from the inside of the exterior body 30 to the outside are opposite directions relative to the exterior body 30, but the present disclosure is not limited to this. For example, the directions in which the positive electrode lead and the negative electrode lead each protrude from the inside of the exterior body 30 to the outside may be the same direction relative to the exterior body 30.

[0153] An example of the lithium ion secondary battery of the present disclosure, which will be described later, is a lithium ion secondary battery obtained by charging and discharging the lithium ion secondary battery precursor 1.

[0154] FIG. 2 is a schematic cross-sectional view showing a coin-type lithium ion secondary battery precursor, which is another example of the lithium ion secondary battery precursor of the present disclosure.

[0155] 2, a disc-shaped negative electrode 42, a separator 45 filled with a non-aqueous electrolyte, a disc-shaped positive electrode 41, and, if necessary, spacer plates 47 and 48 made of stainless steel, aluminum, or the like are stacked in this order and housed between a positive electrode can 43 (hereinafter also referred to as a "battery can") and a sealing plate 44 (hereinafter also referred to as a "battery can lid"). The positive electrode can 43 and the sealing plate 44 are crimped and sealed with a gasket 46 interposed therebetween. In this example, the nonaqueous electrolyte of the present disclosure is used as the nonaqueous electrolyte injected into separator 45 .

[0156] An example of the lithium ion secondary battery of the present disclosure, which will be described later, is a lithium ion secondary battery obtained by charging and discharging the coin-type lithium ion secondary battery precursor shown in FIG.

[0157] [Lithium-ion secondary battery and manufacturing method thereof] The method for producing a lithium ion secondary battery according to the present disclosure includes: a step of preparing the lithium ion secondary battery precursor of the present disclosure (hereinafter also referred to as a "preparation step"); charging and discharging the lithium ion secondary battery precursor; Includes. The lithium ion secondary battery of the present disclosure is a lithium ion secondary battery obtained by charging and discharging the above-described lithium ion secondary battery precursor of the present disclosure.

[0158] According to the lithium ion secondary battery and the method for manufacturing the same of the present disclosure, it is possible to reduce the room temperature resistance increase rate of the lithium ion secondary battery when stored at high temperatures.

[0159] The preparation step may be a step of simply preparing a pre-manufactured lithium ion secondary battery precursor of the present disclosure for a step of charging and discharging, or may be a step of manufacturing a lithium ion secondary battery precursor of the present disclosure. The lithium ion secondary battery precursor is as described above.

[0160] In the step of charging and discharging, the lithium ion secondary battery precursor can be charged and discharged according to a known method. In this step, the lithium ion secondary battery precursor may be subjected to a cycle of charging and discharging multiple times. As described above, this charging and discharging preferably forms an SEI (Solid Electrolyte Interface) film on the surface of the positive electrode (particularly the positive electrode active material) and / or negative electrode (particularly the negative electrode active material) in the lithium ion secondary battery precursor.

[0161] In the step of charging and discharging, the lithium ion secondary battery precursor is preferably subjected to a combination of charging and discharging at least once in an environment of 25°C to 70°C. [Example]

[0162] Examples of the present disclosure will be described below, but the present disclosure is not limited to the following examples. Hereinafter, "%" means "% by mass" unless otherwise specified.

[0163] Example 1: Synthesis of heterocyclic aromatic compound (I-1-1B) lithium [2,2'-bipyridine]-3,3'-dicarboxylate

[0164] [ka]

[0165] [2,2'-bipyridine]-3,3'-dicarboxylate (976.8 mg, 4.0 mmol) and anhydrous lithium hydroxide (191.6 mg, 8.0 mmol) were placed in a nitrogen-purged 100 mL four-neck flask and dried with a heat gun for 5 minutes while stirring under reduced pressure. 15 mL of distilled water was then added and the mixture was stirred at room temperature. 30 minutes after the start of the stirring reaction, 80 mL of acetone was added to precipitate the target product. The resulting reaction solution was filtered, and the residue was washed twice with 50 mL of acetone to obtain a white solid of [2,2'-bipyridine]-3,3'-dicarboxylate (913.0 mg, 3.65 mmol, yield 91%). White solid 1 The results of measurement by H-NMR (chloroform-d) are shown below. 1 H-NMR: δ7.44(m,2H), 8.06(m, 2H), 8.44(m, 2H)

[0166] Example 2: Synthesis of heterocyclic aromatic compound (I-1-1D) lithium [2,2'-bipyridine]-6,6'-dicarboxylate

[0167] [ka]

[0168] [2,2'-bipyridine]-6,6'-dicarboxylate (976.8 mg, 4.0 mmol) and anhydrous lithium hydroxide (191.6 mg, 8.0 mmol) were placed in a nitrogen-purged 1 L four-neck flask and dried with a heat gun for 5 minutes while stirring under reduced pressure. 500 mL of distilled water was then added and the mixture was stirred at room temperature. 30 minutes after the start of the stirring reaction, 300 mL of acetone was added to precipitate the target product. The resulting reaction solution was filtered, and the residue was washed twice with 50 mL of acetone to obtain lithium [2,2'-bipyridine]-6,6'-dicarboxylate (312 mg, 1.25 mmol, yield 31%) as a white solid. White solid 1 The results of measurement by H-NMR (chloroform-d) are shown below. 1 H-NMR: δ7.71(m, 2H), 8.25(m, 2H), 8.63(m, 2H)

[0169] Example 3 <Preparation of non-aqueous electrolyte> Ethylene carbonate (hereinafter referred to as "EC"), dimethyl carbonate (hereinafter referred to as "DMC"), and ethyl methyl carbonate (hereinafter referred to as "EMC") were mixed in a volume ratio of EC:DMC:EMC = 30:35:35, thereby obtaining a mixed solvent as a non-aqueous solvent. LiPF6 as an electrolyte was dissolved in the obtained mixed solvent so that the concentration in the finally obtained non-aqueous electrolyte solution was 1 mol / L, thereby obtaining an electrolyte solution (hereinafter also referred to as "basic electrolyte solution"). To the obtained base electrolyte solution, a compound represented by the following formula (I-1-1A), which is a specific example of the compound represented by the above formula (I-1), was added as an additive so that the content relative to the total amount of the finally obtained non-aqueous electrolyte solution would be the content (mass %) shown in Table 1, thereby obtaining a non-aqueous electrolyte solution. [ka]

[0170] <Preparation of positive electrode> LiNi as a positive electrode active material 0.5 Co 0.2 Mn 0.3 A mixture of O2 (94% by mass), carbon black (3% by mass) as a conductive additive, and polyvinylidene fluoride (PVdF) (3% by mass) as a binder was obtained, and the resulting mixture was dispersed in N-methylpyrrolidone solvent to obtain a positive electrode composite slurry. An aluminum foil with a thickness of 20 μm was prepared as a positive electrode current collector. The resulting positive electrode mixture slurry was applied to an aluminum foil, dried, and then rolled in a press to obtain a sheet-shaped positive electrode, which was composed of a positive electrode current collector and a positive electrode active material layer.

[0171] <Preparation of negative electrode> Graphite (96% by mass) was used as the negative electrode active material, carbon black (1% by mass) was used as a conductive additive, 1% by mass of sodium carboxymethyl cellulose dispersed in pure water as a thickener in terms of solid content, and 2% by mass of styrene-butadiene rubber (SBR) dispersed in pure water as a binder in terms of solid content were mixed together to obtain a negative electrode composite slurry. A copper foil with a thickness of 10 μm was prepared as a negative electrode current collector. The resulting negative electrode mixture slurry was applied to a copper foil, dried, and then rolled in a press to obtain a sheet-shaped negative electrode, which was composed of a negative electrode current collector and a negative electrode active material layer.

[0172] <Preparing the separator> A porous polyethylene film was prepared as a separator.

[0173] <Fabrication of lithium-ion secondary batteries> The negative electrode was punched out into a disk shape with a diameter of 14 mm, the positive electrode was punched out into a disk shape with a diameter of 13 mm, and the separator was punched out into a disk shape with a diameter of 17 mm, thereby obtaining a coin-shaped negative electrode, coin-shaped positive electrode, and coin-shaped separator, respectively. The obtained coin-shaped negative electrode, coin-shaped separator, and coin-shaped positive electrode were stacked in this order in a stainless steel battery can (size: 2032). Next, 28 μL of non-aqueous electrolyte was poured into the battery can, and the separator, positive electrode, and negative electrode were immersed in the non-aqueous electrolyte. Next, an aluminum plate (thickness 1.2 mm, diameter 16 mm) and a spring were placed on the positive electrode, and the battery case lid was crimped via a polypropylene gasket to seal the battery. As a result of the above, a coin-type lithium ion secondary battery precursor (i.e., a lithium ion secondary battery before being charged and discharged) was obtained having the configuration shown in Figure 2. The lithium ion secondary battery precursor had a diameter of 20 mm and a height of 3.2 mm.

[0174] <Fabrication of lithium-ion secondary batteries> The lithium ion secondary battery precursor was charged to 1.5 V to 4.2 V, held for 5 to 50 hours, charged to 4.2 V, and discharged to 2.5 V in this order at a temperature range of 25°C to 70°C to obtain a lithium ion secondary battery.

[0175] <Measurement of initial room temperature resistance> The resulting lithium-ion secondary battery was charged to 3.7 V, and then measured for each voltage drop (= voltage before discharge started - voltage 10 seconds after discharge started) due to CC10s discharge at discharge rates of 0.1 C to 0.6 C in a thermostatic chamber at 25°C. CC10s discharge refers to discharge at a constant current for 10 seconds. The DC resistance [Ω], which represents the initial room-temperature resistance, was calculated based on each voltage drop and each current value (i.e., each current value corresponding to a discharge rate of 0.1 C to 0.6 C). Similarly, for Comparative Example 1 described later, the DC resistance [Ω] was determined as the initial room temperature resistance.

[0176] <Measurement of initial low-temperature resistance> After measuring the initial room-temperature resistance, the lithium-ion secondary battery was charged at 3.7 V, and then placed in a thermostatic chamber at a temperature of -10°C. The amount of voltage drop (= voltage before discharge started - voltage 10 seconds after discharge started) due to CC10s discharge at discharge rates of 0.1 C to 0.6 C was measured. Here, CC10s discharge refers to discharge at a constant current for 10 seconds. Based on the obtained amount of voltage drop and each current value (i.e., each current value corresponding to a discharge rate of 0.1 C to 0.6 C), the DC resistance [Ω] was calculated as the initial room-temperature resistance. The DC resistance [Ω] was similarly determined as the initial low-temperature resistance for Comparative Example 1 described below.

[0177] <High temperature storage> Next, the lithium ion secondary battery after measuring the initial low-temperature resistance was charged to 4.2 V, and the charged lithium ion secondary battery was stored in a thermostatic chamber at 60° C. for 14 days (hereinafter referred to as "high-temperature storage").

[0178] <Measurement of room temperature resistance after high temperature storage> The lithium ion secondary battery after high-temperature storage was discharged to 2.5 V, and then the room-temperature resistance after high-temperature storage was measured in the same manner as in the measurement of the initial room-temperature resistance. Similarly, for Comparative Example 1 described later, the DC resistance [Ω] was determined as the room temperature resistance after high temperature storage.

[0179] <Measurement of low-temperature resistance after high-temperature storage> The lithium ion secondary battery whose room temperature resistance after high temperature storage had been measured was discharged to 2.5 V, and then the room temperature resistance after high temperature storage was measured in the same manner as in measuring the initial room temperature resistance. In addition, for Comparative Example 1 described later, the DC resistance [Ω] was similarly determined as the low-temperature resistance after high-temperature storage.

[0180] <Calculation of the rate of increase in low-temperature resistance during high-temperature storage> The low-temperature resistance increase rate (%) during high-temperature storage was calculated using the following formula. Low-temperature resistance increase rate during high-temperature storage (%) = (low-temperature resistance after high-temperature storage / initial low-temperature resistance) x 100 The rate of increase in low-temperature resistance (%) during high-temperature storage was calculated in the same manner for Comparative Example 1 described later. Then, assuming that the low-temperature resistance increase rate during high-temperature storage of Comparative Example 1 was 100, the low-temperature resistance increase rate (relative value) during high-temperature storage of Example 1 was determined. The results are shown in Table 1.

[0181] [Examples 4 to 10, Comparative Example 1] The same operations as in Example 3 were carried out, except that the type and content of additives (compounds represented by the following formulas) used in preparing the non-aqueous electrolytes were changed as shown in Table 1. The results are shown in Table 1. The additives added to the non-aqueous electrolytes of Examples 4 to 10 and Comparative Example 1 are represented by the following formulas. In Table 1, "-" means that no additive was added.

[0182] [ka]

[0183] [Table 1]

[0184] As shown in Table 1, the nonaqueous electrolyte solutions of the examples containing the above-mentioned specified additives were able to suppress the increase in resistance of nonaqueous electrolyte secondary batteries when stored for long periods in a high-temperature environment, compared to the nonaqueous electrolyte solution of Comparative Example 1. [Explanation of symbols]

[0185] 1. Lithium secondary battery precursor 10 Battery element 11 Positive electrode 11A positive electrode current collector 11B Positive electrode composite layer 12 Negative electrode 12A negative electrode current collector 12B Negative electrode composite layer 13 Separator 14 Cell layer 21 Positive lead 22 Negative lead 30 Exterior body 41 Positive electrode 42 Negative electrode 43 Positive electrode can 44 Sealing plate 45 Separator 46 Gasket 47, 48 Spacer plates

Claims

1. A non-aqueous electrolyte solution containing at least one heterocyclic aromatic compound selected from the group consisting of a compound represented by the following formula (I-1), a compound represented by the following formula (I-2), a compound represented by the following formula (I-3), a compound represented by the following formula (I-4), and a compound represented by the following formula (I-5). 【Chemical 1】 (In formulas (I-1) to (I-5), Ar represents a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-1), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-2), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-3), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-4), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-5), or an aromatic hydrocarbon group represented by the following formula (Ar-6), and M １ ＋ each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion, and x represents 1 or 2. 【Chemistry 2】 (In formula (Ar-1) to formula (Ar-6), M １ ＋ each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion, and y represents an integer of 0 to 2.

2. The compound represented by formula (I-1) is a compound represented by the following formula (I-1-1), a compound represented by the following formula (I-1-2), a compound represented by the following formula (I-1-3), a compound represented by the following formula (I-1-4), a compound represented by the following formula (I-1-5), and a compound represented by the following formula (I-1-6). The nonaqueous electrolyte solution according to claim 1, wherein the compound is at least one heterocyclic aromatic compound selected from the group consisting of: 【Chemistry 3】 (In formulas (I-1-1) to (I-1-6), M １ ＋ each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion, x represents 1 or 2, and y represents an integer of 0 to 2.

3. 2. The non-aqueous electrolyte according to claim 1, wherein the total content of the heterocyclic aromatic compounds is 0.01% by mass to 5.0% by mass based on the total amount of the non-aqueous electrolyte.

4. The nonaqueous electrolyte solution according to claim 1, further comprising at least one compound selected from the group consisting of a difluorophosphate represented by the following formula (II-1), a monofluorophosphate represented by the following formula (II-2), a salt represented by the following formula (III), a cyclic sulfate ester compound represented by the following formula (IV), a cyclic sulfonate ester compound represented by the following formula (V), and a cyclic carbonate compound represented by the following formula (VI). 【Chemistry 4】 (In formulas (II-1) and (II-2), M ２ ＋ each independently represents an alkali metal ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion. In formula (III), R ３ each independently represents a single bond (-) or a divalent hydrocarbon group having 1 to 6 carbon atoms which may contain a halogeno group as a substituent; Q ３ each independently represents an oxa group (—O—) or a secondary amino group (—NH—), and X ３ each independently represents a halogeno group; Z ３ represents a boron atom or a phosphorus atom, M ３ ＋ represents an alkali metal ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion; h represents Z ３ When is a boron atom, 1 or 2 is used, and Z ３ represents an integer of 1 to 3 when is a phosphorus atom, and i is Z ３ is 0 or 2 when is a boron atom, Z ３ represents 0, 2, or 4 when is a phosphorus atom. In formula (IV), R ４１ represents a group represented by formula (iv-1), a group represented by formula (iv-2), or a divalent hydrocarbon group having 1 to 6 carbon atoms, In formula (iv-1), R ４２ is an oxymethylene group (-OCH ２ -), oxyethylene group (-OCH ２ CH ２ -), an oxa group (-O-), or a divalent hydrocarbon group having 1 to 6 carbon atoms; In formula (iv-2), R ４３ represents a hydrocarbon group having 1 to 8 carbon atoms. In formula (V), R ５ each independently represents a halogeno group, a fluorocarbon group having 1 to 12 carbon atoms, or a hydrocarbon group having 1 to 12 carbon atoms which may contain at least one functional group selected from the group consisting of a halogeno group and an oxa group (—O—) as a substituent, and j represents an integer of 0 to 3. In formula (VI), R ６ each independently represents a halogeno group, a fluorocarbon group having 1 to 12 carbon atoms, or a hydrocarbon group having 1 to 12 carbon atoms which may contain at least one functional group selected from the group consisting of a halogeno group and an oxa group (—O—) as a substituent, and k represents an integer of 0 to 2.

5. A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, a non-aqueous electrolyte, and a separator, A non-aqueous electrolyte secondary battery, wherein the non-aqueous electrolyte is the non-aqueous electrolyte according to any one of claims 1 to 4.

6. A negative electrode for a non-aqueous electrolyte secondary battery, comprising: a current collector; and a negative electrode mixture layer formed on the current collector and containing a negative electrode active material, The negative electrode for a non-aqueous electrolyte secondary battery, wherein the negative electrode mixture layer contains at least one heterocyclic aromatic compound selected from the group consisting of a compound represented by the following formula (I-1), a compound represented by the following formula (I-2), a compound represented by the following formula (I-3), a compound represented by the following formula (I-4), and a compound represented by the following formula (I-5). 【Chemistry 5】 (In formulas (I-1) to (I-5), Ar represents a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-1), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-2), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-3), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-4), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-5), or an aromatic hydrocarbon group represented by the following formula (Ar-6), and M １ ＋ each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion, and x represents 1 or 2. 【Chemistry 6】 (In formula (Ar-1) to formula (Ar-6), M １ ＋ each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion, and y represents an integer of 0 to 2.

7. A positive electrode for a non-aqueous electrolyte secondary battery, comprising: a current collector; and a positive electrode mixture layer formed on the current collector and containing a positive electrode active material, The positive electrode for a non-aqueous electrolyte secondary battery, wherein the positive electrode mixture layer contains at least one heterocyclic aromatic compound selected from the group consisting of a compound represented by the following formula (I-1), a compound represented by the following formula (I-2), a compound represented by the following formula (I-3), a compound represented by the following formula (I-4), and a compound represented by the following formula (I-5). 【Chemistry 7】 (In formulas (I-1) to (I-5), Ar represents a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-1), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-2), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-3), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-4), a heterocyclic aromatic hydrocarbon group represented by the following formula (Ar-5), or an aromatic hydrocarbon group represented by the following formula (Ar-6), and M １ ＋ each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion, and x represents 1 or 2. 【Chemistry 8】 (In formula (Ar-1) to formula (Ar-6), M １ ＋ each independently represents an alkali metal ion, a hydrogen ion, an ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, or a piperidinium ion, and y represents an integer of 0 to 2.

8. A heterocyclic aromatic compound represented by the following formula (I-1-1B) or (I-1-1D): 【Chemistry 9】

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