Non-aqueous secondary battery and method for manufacturing non-aqueous secondary battery

Abstract

This nonaqueous secondary battery is provided with: a nonaqueous electrolyte solution which contains a compound (A) that is represented by formula (I); a positive electrode which contains a positive electrode active material containing a compound (B) that is represented by formula (II); and a negative electrode. The content of the compound (A) is more than 0% by mass but less than 1.0% by mass relative to the total mass of the nonaqueous electrolyte solution. In formula (I), X+ represents an ion that is selected from among a hydrogen ion, a lithium ion, a sodium ion and a potassium ion. In formula (II), 0.1 ≤ a < 1.3, 0.1 < 1 - b - c < 1.0, 0 < b < 0.6 and 0 < c < 0.6.

Description

[Technical field]

[0001] The present disclosure relates to a nonaqueous secondary battery and a method for manufacturing a nonaqueous secondary battery. [Background technology]

[0002] Non-aqueous secondary batteries have been attracting attention as batteries with high energy density.

[0003] Patent Document 1 discloses a nonaqueous electrolyte secondary battery (hereinafter referred to as "nonaqueous secondary battery"). The nonaqueous secondary battery disclosed in Patent Document 1 includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The negative electrode is made of lithium or a negative electrode material capable of absorbing and releasing lithium. The nonaqueous electrolyte is made of an organic solvent and a solute. The organic solvent contains at least one of lithium monofluorophosphate and lithium difluorophosphate.

[0004] Patent Document 2 discloses a lithium ion battery (hereinafter, referred to as a "non-aqueous secondary battery"). The non-aqueous secondary battery specifically disclosed in Patent Document 2 includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode is LiNi 0.5 Co 0.3 Mn 0.2 O 2 The positive electrode active material includes graphite. The negative electrode includes a negative electrode active material including graphite. The non-aqueous electrolyte includes acesulfame Li. The content of acesulfame Li is 1 mass %, 7 mass %, or 14 mass % based on the total amount of the non-aqueous electrolyte.

[0005] Patent document 1: Patent No. 3439085 Patent Document 2: China Patent Application Publication No. 111333595 Summary of the Invention [Problem to be solved by the invention]

[0006] However, a nonaqueous electrolyte secondary battery such as that disclosed in Patent Document 1 may be prone to an increase in direct current resistance and a decrease in discharge capacity when stored in a fully charged state in a high temperature environment (e.g., 60°C) for a long period of time (e.g., 14 days).

[0007] The present inventors carried out a reproducing experiment of the non-aqueous secondary battery specifically disclosed in Patent Document 2. As a result, it was found that the content of acesulfame Li was 1 mass % or more with respect to the total amount of the non-aqueous electrolyte. adjustment It was experimentally confirmed that Acesulfame Li does not dissolve in the non-aqueous electrolyte, and that insoluble components remain in the non-aqueous electrolyte. Therefore, it was experimentally confirmed that the non-aqueous electrolyte specifically disclosed in Patent Document 2 cannot be used as the non-aqueous electrolyte for a non-aqueous secondary battery from the viewpoint of reliably preventing a short circuit between the positive electrode and the negative electrode, and from the viewpoint of allowing the non-aqueous electrolyte to fully permeate the positive electrode and the negative electrode.

[0008] In view of the above circumstances, the present disclosure provides a nonaqueous secondary battery in which an acesulfame compound is dissolved in a nonaqueous electrolyte and in which an increase in direct current resistance and a decrease in discharge capacity are suppressed even when the battery is stored for a long period of time in a fully charged state under a high temperature environment, and a method for producing the nonaqueous secondary battery. The acesulfame compound includes acesulfame Li, acesulfame Na, acesulfame K, or acesulfame H. [Means for solving the problem]

[0009] Means for solving the above problems include the following aspects. <1> A non-aqueous electrolyte solution containing a compound (A) represented by the following formula (I); A positive electrode including a positive electrode active material including a compound (B) represented by the following formula (II); Negative electrode and Equipped with The content of the compound (A) is more than 0 mass % and less than 1.0 mass % with respect to the total amount of the nonaqueous electrolyte.

[0010] [ka]

[0011] (In formula (I), X + represents one selected from a hydrogen ion, a lithium ion, a sodium ion, and a potassium ion.

[0012] [ka]

[0013] (In formula (II), 0.1≦a<1.3, 0.1<1-bc<1.0, 0 <b<0.6、0<c<0.6である。)

[0014] <2> The compound (A) is + is a lithium ion. <1> The non-aqueous secondary battery according to claim 1. <3> The compound (A) is + is a potassium ion. <1> The non-aqueous secondary battery according to claim 1. <4> The non-aqueous electrolyte contains a non-aqueous solvent containing ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. <1> ~ <3> 13. The nonaqueous secondary battery according to claim 12, <5> The compound (B) is LiNi 0.5 Co 0.2 Mn 0.3 O 2 or a compound represented by LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 The compound represented by the formula: <1> ~ <4> 13. The nonaqueous secondary battery according to claim 12, <6> The non-aqueous electrolyte does not contain propylene carbonate. <1> ~ <5> 13. The nonaqueous secondary battery according to claim 12, <7> The non-aqueous electrolyte contains a compound (X), The compound (X) is At least one compound selected from the group consisting of lithium monofluorophosphate and lithium difluorophosphate; A compound represented by the following formula (III), A compound represented by the following formula (IV), A compound represented by the following formula (V): At least one selected from the group consisting of <1> ~ <6> 13. The nonaqueous secondary battery according to claim 12,

[0015] [ka]

[0016] [In formula (III), R 11 and R 12 are each independently a hydrogen atom, a methyl group, an ethyl group, or a propyl group. In formula (IV), R 21 represents an oxygen atom, an alkylene group having 1 to 6 carbon atoms, an alkenylene group having 1 to 6 carbon atoms, or a vinylene group; R 22 represents an alkylene group having 1 to 6 carbon atoms, a group represented by the above formula (iv-1), or a group represented by the above formula (iv-2). * indicates a bonding position. In the above formula (iv-2), R 23 represents a group represented by an alkyl group having 1 to 6 carbon atoms. In formula (V), M represents an alkali metal, b represents an integer of 1 to 3, m represents an integer of 1 to 4, n represents an integer of 0 to 8, and q represents 0 or 1. 31 represents an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (these groups may contain a substituent or a heteroatom in the structure, and when q is 1 and m is 2 to 4, m R 31 Each of them may be bonded. 32 is a halogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms (these groups may contain a substituent or a heteroatom in the structure, and when n is 2 to 8, n R 32 may be bonded to each other to form a ring;1 , and Q 2 each independently represents an oxygen atom or a carbon atom.

[0017] <8> A preparation step of preparing a non-aqueous secondary battery precursor; an aging step of charging and discharging the nonaqueous secondary battery precursor, The nonaqueous secondary battery precursor is A non-aqueous electrolyte solution containing a compound (A) represented by the following formula (I); A positive electrode including a positive electrode active material including a compound (B) represented by the following formula (II); A negative electrode; Including, A method for producing a nonaqueous secondary battery, wherein the content of the compound (A) is more than 0 mass % and less than 1.0 mass % with respect to the total amount of the nonaqueous electrolyte solution.

[0018] [ka]

[0019] (In formula (I), X + represents one selected from a hydrogen ion, a lithium ion, a sodium ion, and a potassium ion.

[0020] [ka]

[0021] (In formula (II), 0.1≦a<1.3, 0.1<1-bc<1.0, 0 <b<0.6、0<c<0.6である。) Effect of the Invention

[0022] According to the present disclosure, there is provided a nonaqueous secondary battery in which an acesulfame compound is dissolved in a nonaqueous electrolyte and in which an increase in direct current resistance and a decrease in discharge capacity are suppressed even when the battery is stored for a long period of time in a fully charged state in a high-temperature environment, and a method for manufacturing the nonaqueous secondary battery are provided. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic perspective view showing an example of a laminate type battery, which is an example of a nonaqueous secondary battery according to the present disclosure. [Diagram 2] 2 is a schematic cross-sectional view in the thickness direction of a laminated electrode body housed in the laminated battery shown in FIG. 1. [Diagram 3] FIG. 2 is a schematic cross-sectional view showing an example of a coin-type battery, which is another example of a nonaqueous secondary battery according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] In this specification, 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 this specification, the amount of each component in a composition means, when a plurality of substances corresponding to each component are present in the composition, the total amount of the plurality of substances present in the composition, unless otherwise specified.

[0025] [Nonaqueous secondary battery] The nonaqueous secondary battery of the present disclosure includes a nonaqueous electrolyte solution containing a compound (A) represented by the following formula (I), a positive electrode containing a positive electrode active material containing a compound (B) represented by the following formula (II), and a negative electrode. The content of the compound (A) is more than 0 mass % and 1.0 mass % based on the total amount of the nonaqueous electrolyte. % is less than.

[0026] [ka]

[0027] In formula (I), X + represents one ion selected from a hydrogen ion, a lithium ion, a sodium ion, and a potassium ion.

[0028] [ka]

[0029] In formula (II), 0.1 ≦ a < 1.3, 0.1 < 1 - b - c < 1.0, 0 < b < 0.6, and 0 < c < 0.6.

[0030] Since the non-aqueous secondary battery of the present disclosure has the above configuration, when the acesulfame compound is dissolved in the non-aqueous electrolyte and stored for a long time in a fully charged state under a high-temperature environment (hereinafter referred to as "high-temperature long-term storage"), an increase in DC resistance and a decrease in discharge capacity are suppressed as compared with a configuration not containing compound (A). It is presumed that the suppression of the increase in DC resistance as compared with a configuration not containing compound (A) even after high-temperature long-term storage is mainly due to the following reasons. When the non-aqueous secondary battery of the present disclosure is charged or discharged (hereinafter referred to as "charge-discharge"), it is considered that a solid electrolyte interface layer (SEI: Solid Electrolyte Interphase) film (hereinafter referred to as "SEI film") is formed on the surface of the negative electrode and the surface of the positive electrode. Hereinafter, the SEI film of the negative electrode and the SEI film of the positive electrode may be simply referred to as "SEI film". The SEI film is considered to be mainly formed by lithium ions in the non-aqueous electrolyte and decomposition products of the non-aqueous electrolyte decomposed by charge-discharge of the non-aqueous secondary battery. When the SEI film is formed, it is considered that side reactions other than the original battery reaction are less likely to proceed in the charge-discharge cycle of the non-aqueous secondary battery. The battery reaction indicates a reaction in which lithium ions enter and exit (intercalate) the positive electrode and the negative electrode. Side reactions include a reduction decomposition reaction of the electrolyte by the negative electrode, an oxidation decomposition reaction of the electrolyte by the positive electrode, elution of metal elements in the positive electrode active material, and the like. On the other hand, the SEI film of the negative electrode tends to thicken with each charge and discharge. Lithium ions in the non-aqueous electrolyte are consumed to thicken the SEI film of the negative electrode. Therefore, the thickening of the SEI film of the negative electrode is considered to be one of the factors that increase the DC resistance of the non-aqueous secondary battery. In particular, the thickening of the SEI film of the negative electrode becomes significant when the non-aqueous secondary battery is exposed to a high-temperature environment. In addition, when at least one of Mn ions, Ni ions, and Co ions (hereinafter referred to as "Mn ions, etc."), which are metal components of the positive electrode, dissolves into the non-aqueous electrolyte, the Mn ions, etc. are deposited on the surface of the negative electrode, promoting the decomposition reaction of the non-aqueous electrolyte. Therefore, the dissolution of Mn ions, etc. from the positive electrode is also considered to be one of the factors that increase the DC resistance of the non-aqueous secondary battery. In particular, the dissolution of Mn ions, etc. from the positive electrode becomes significant when the non-aqueous secondary battery is exposed to a high-temperature environment. In order to suppress the dissolution of the metal from the positive electrode, an additive (compound (A)) that can be coordinated to the metal of the positive electrode can be added to the non-aqueous electrolyte to suppress the dissolution of the metal from the positive electrode. The additive (compound (A)) that can be coordinated to the metal of the positive electrode can stabilize the metal on the surface of the positive electrode active material by coordinating to the metal of the positive electrode. The reason why the DC resistance of the nonaqueous secondary battery according to the present disclosure is unlikely to increase even when stored at high temperature for a long period of time is presumably because compound (A) suppresses thickening of the SEI film of the negative electrode and elution of Mn ions and the like from the positive electrode. Furthermore, even when stored at high temperature for a long period of time, the discharge capacity is less likely to decrease than in a configuration not containing compound (A). This is presumably because, as described above, compound (A) suppresses the thickening of the SEI film of the negative electrode and the elution of Mn ions and the like from the positive electrode, and therefore, even when the nonaqueous secondary battery is exposed to a high-temperature environment, the progress of side reactions is suppressed and the discharge capacity is less likely to decrease.

[0031] (Non-aqueous electrolyte) The nonaqueous secondary battery of the present disclosure includes a nonaqueous electrolyte solution. The nonaqueous electrolyte solution of the present disclosure contains compound (A). The non-aqueous electrolyte may contain one type of compound (A) alone or two or more types of compound (A).

[0032] <Compound (A)> The compound (A) is represented by the following formula (I).

[0033] [ka]

[0034] In formula (I), X + represents one ion selected from a hydrogen ion, a lithium ion, a sodium ion, and a potassium ion.

[0035] Below, X + Compound (A) where X is a hydrogen ion is called "acesulfamic acid". + The compound (A) where X is a lithium ion is called "acesulfame Li". + Compound (A) where X is a sodium ion is called "acesulfame Na". + Potassium ion The compound (A) is called "acesulfame K".

[0036] Among them, X + is preferably a lithium ion or a potassium ion, and more preferably a lithium ion. In other words, compound (A) is preferably acesulfame Li or acesulfame K, and more preferably acesulfame Li. When the compound (A) is Acesulfame K, even if the nonaqueous secondary battery is stored at high temperature for a long period of time, the increase in direct current resistance and the decrease in discharge capacity of the nonaqueous secondary battery can be suppressed more than in a configuration not containing the compound (A). This is presumably mainly because the addition of Acesulfame K to the nonaqueous electrolyte suppresses metal elution from the positive electrode even if the nonaqueous secondary battery is stored at high temperature for a long period of time. When the compound (A) is acesulfame Li, an increase in the direct current resistance and a decrease in the discharge capacity of the nonaqueous secondary battery can be suppressed more effectively than in the case where the compound (A) is acesulfame K, even if the nonaqueous secondary battery is stored at high temperature for a long period of time.

[0037] The content of compound (A) is more than 0 mass% and less than 1.0 mass%, preferably 0.05 mass% to 0.8 mass%, more preferably 0.1 mass% to 0.6 mass%, still more preferably 0.2 mass% to 0.5 mass%, and particularly preferably 0.3 mass% to 0.5 mass%, relative to the total amount of the nonaqueous electrolyte. When the content of compound (A) is within the above range, compound (A) is completely dissolved in the nonaqueous electrolyte. Therefore, when assembling a nonaqueous secondary battery, injection of the nonaqueous electrolyte can be easily performed. When the content of compound (A) is within the above range, even if the nonaqueous secondary battery is stored for a long period of time in a fully charged state under a high temperature environment, an increase in the direct current resistance and a decrease in the discharge capacity of the nonaqueous secondary battery can be suppressed.

[0038] <Non-aqueous solvent> The non-aqueous electrolyte of the present disclosure may contain a non-aqueous solvent.

[0039] As the non-aqueous solvent, various known ones can be appropriately selected. As the non-aqueous solvent, for example, the non-aqueous solvents described in paragraphs 0069 to 0087 of JP2017-45723A can be used.

[0040] The non-aqueous solvent preferably contains a cyclic carbonate compound and a chain carbonate compound. The cyclic carbonate compound and the chain carbonate compound may each be of only one type or of two or more types.

[0041] Examples of the cyclic carbonate compound include ethylene carbonate (hereinafter sometimes referred to as "EC"), propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, and 2,3-pentylene carbonate. Among these, the cyclic carbonate compound preferably contains ethylene carbonate, which has a high dielectric constant. In particular, when the negative electrode active material of the nonaqueous secondary battery contains graphite, it is more preferable that the nonaqueous solvent contains ethylene carbonate.

[0042] The nonaqueous electrolyte of the present disclosure preferably does not contain propylene carbonate. When the negative electrode active material of the nonaqueous secondary battery contains graphite, the nonaqueous solvent does not contain propylene carbonate, so that the lithium ions and the propylene carbonate solvent can be prevented from being inserted into the graphite negative electrode, and as a result, the graphite negative electrode can be prevented from peeling off, and the discharge capacity of the nonaqueous secondary battery can be prevented from decreasing and the DC resistance can be prevented from increasing.

[0043] Examples of the chain carbonate compound include dimethyl carbonate (hereinafter sometimes referred to as "DMC"), ethyl methyl carbonate (hereinafter sometimes referred to as "EMC"), diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl propyl carbonate, dipropyl carbonate, methyl butyl carbonate, ethyl butyl carbonate, dibutyl carbonate, methyl pentyl carbonate, ethyl pentyl carbonate, dipentyl carbonate, methyl heptyl carbonate, ethyl heptyl carbonate, diheptyl carbonate, methyl hexyl carbonate, ethyl hexyl carbonate, dihexyl carbonate, methyl octyl carbonate, ethyl octyl carbonate, and dioctyl carbonate.

[0044] Cyclic Carbonates compound and linear carbonate compound The combination is not particularly limited. The non-aqueous electrolyte preferably contains, as a non-aqueous solvent, EC, DMC, and EMC. When the negative electrode active material of a non-aqueous secondary battery contains graphite, the non-aqueous solvent contains EC, which allows the formation of an SEI film in the negative electrode through which lithium ions can move smoothly and efficiently. EC is a solid at room temperature, so it has high viscosity even when melted. By mixing EC with DMC and EMC, which have low viscosity, the non-aqueous solvent has a moderate viscosity. This is thought to make it easier for lithium ions in the non-aqueous electrolyte to move at high speed. As a result, the battery performance of the non-aqueous secondary battery is improved.

[0045] The mixing ratio of the cyclic carbonate compound and the chain carbonate compound is, for example, 5:95 to 80:20, preferably 10:90 to 70:30, and more preferably 15:85 to 55:45, expressed as a mass ratio of the cyclic carbonate compound to the chain carbonate compound. By setting such a ratio, the increase in viscosity of the non-aqueous electrolyte can be suppressed, and the dissociation degree of the electrolyte described below can be increased. Therefore, the conductivity of the non-aqueous electrolyte, which is related to the charge / discharge characteristics of the non-aqueous secondary battery, can be increased. Furthermore, the solubility of the electrolyte can be further increased. Therefore, a non-aqueous electrolyte having excellent electrical conductivity at room temperature or low temperature can be obtained. Therefore, the load characteristics of the non-aqueous secondary battery at room temperature to low temperature can be improved.

[0046] The non-aqueous solvent may contain compounds other than the cyclic carbonate compound and the chain carbonate compound. In this case, the other compound contained in the non-aqueous solvent may be only one type, or may be two or more types. Other compounds include cyclic carboxylate compounds (e.g., gamma-butyrolactone), cyclic sulfone compounds, cyclic ether compounds, chain carboxylate compounds, chain ether compounds, chain phosphate compounds, amide compounds, chain carbamate compounds, cyclic amide compounds, cyclic urea compounds, boron compounds, polyethylene glycol derivatives, and the like. For these compounds, the descriptions in paragraphs 0069 to 0087 of JP2017-45723A can be referred to as appropriate.

[0047] The proportion of the cyclic carbonate compound and the chain carbonate compound in the non-aqueous solvent is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The proportion of the cyclic carbonate compound and the chain carbonate compound in the non-aqueous solvent may be 100% by mass.

[0048] When the non-aqueous solvent contains EC, DMC, and EMC, the mixing ratio of EC, DMC, and EMC is not particularly limited, and is preferably 30:35:35 by volume.

[0049] The proportion of the non-aqueous solvent in the non-aqueous electrolyte solution varies depending on the contents of other components (electrolyte, additives, etc.), but is preferably 60% by mass to 99% by mass, more preferably 70% by mass to 97% by mass, and even more preferably 70% by mass to 90% by mass.

[0050] <Electrolyte> The nonaqueous electrolyte solution of the present disclosure preferably contains an electrolyte. The electrolyte preferably comprises a lithium salt. The lithium salt is LiPF 6 It is preferred that the compound contains The electrolyte is LiPF 6 When LiPF is contained in the electrolyte, 6 The ratio is preferably 10% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, and further preferably 70% by mass to 100% by mass.

[0051] The concentration of the electrolyte in the nonaqueous electrolyte solution of the present disclosure is preferably 0.1 mol / L to 3 mol / L, and more preferably 0.5 mol / L to 2 mol / L. LiPF in the nonaqueous electrolyte of the present disclosure 6 The concentration of is preferably 0.1 mol / L to 3 mol / L, and more preferably 0.5 mol / L to 2 mol / L.

[0052] The electrolyte is LiPF 6 In the case where the electrolyte contains LiPF 6 It may contain other compounds. LiPF 6 Examples of compounds other than the above include alkyl ammonium salts and lithium salts (i.e., LiPF 6 Lithium salts other than those mentioned above. Examples of alkyl ammonium salts include (C 2 H 5 ) 4 NPF6 , (C 2 H 5 ) 4 NBF 4 , (C 2 H 5 ) 4 NClO 4 , (C 2 H 5 ) 4 NAsF 6 , (C 2 H 5 ) 4 N 2 SiF 6 , (C 2 H 5 ) 4 NOSO 2 C k F (2k+1) (k = an integer from 1 to 8), (C 2 H 5 ) 4 NPF n [C k F (2k+1) ] (6-n) (n=an integer of 1 to 5, k=an integer of 1 to 8), etc. Lithium salts (i.e., LiPF 6 Examples of lithium salts other than LiBF 4 , LiClO 4 , LiAsF 6 , Li 2 SiF 6 , LiiOSO 2 C k F (2k+1) (k = an integer from 1 to 8), LiPF n [C k F (2k+1) ] (6-n) (n = 1 to 5, k = an integer from 1 to 8), LiC(SO 2 R 7 )(SO 2 R 8 )(SO 2 R 9 ), LiN(SO 2 OR 10 )(SO 2 OR 11 ), LiN(SO 2 R 12 )(SO 2 R 13) (where R 7 ~R 13 may be the same or different and are a fluorine atom or a perfluoroalkyl group having 1 to 8 carbon atoms).

[0053] <Additives> The nonaqueous electrolyte of the present disclosure may contain an additive, which can suppress the progression of side reactions during the charge-discharge cycle of the nonaqueous secondary battery, thereby improving the battery performance of the nonaqueous secondary battery. The non-aqueous electrolyte may contain one type of additive alone or two or more types of additives.

[0054] The additive preferably contains the compound (X). In other words, the nonaqueous electrolyte of the present disclosure preferably contains the compound (X). This makes it possible to suppress an increase in the direct current resistance of the nonaqueous secondary battery, even when the nonaqueous electrolyte is stored at high temperature for a long period of time, compared to a configuration that does not contain the compound (X).

[0055] Compound (X) is At least one compound selected from the group consisting of lithium monofluorophosphate and lithium difluorophosphate (hereinafter referred to as "lithium fluorophosphate compound"); A compound represented by the following formula (III) (hereinafter referred to as "cyclic carbonate compound (III)"), A compound represented by the following formula (IV) (hereinafter referred to as "cyclic sulfur-containing ester compound (IV)"), A compound represented by the following formula (V) (hereinafter referred to as "cyclic dicarbonyl compound (V)") It is preferable that the material is at least one selected from the group consisting of: The cyclic carbonate compound (III), the cyclic sulfur-containing ester compound (IV), and the cyclic dicarbonyl compound (V) will be described in detail later.

[0056] [ka]

[0057] The nonaqueous electrolyte may contain one type of compound (X) alone or two or more types. The more types of compound (X) the nonaqueous electrolyte contains, the more likely it is that the nonaqueous electrolyte can suppress an increase in direct current resistance and a decrease in discharge capacity even when the nonaqueous secondary battery is stored at high temperature for a long period of time.

[0058] (Lithium fluorophosphate compounds) The additive preferably contains a lithium fluorophosphate compound.

[0059] By containing a lithium fluorophosphate compound in addition to compound (A), the nonaqueous electrolyte can suppress an increase in the direct current resistance of the nonaqueous secondary battery even during long-term storage at high temperature, more than in a configuration not containing compound (X).

[0060] The lithium fluorophosphate compound is either or both of lithium monofluorophosphate and lithium difluorophosphate.

[0061] When the non-aqueous electrolyte contains a lithium fluorophosphate compound, the content of the lithium fluorophosphate compound is preferably 0.001 mass% to 10 mass%, more preferably 0.003 mass% to 5.0 mass%, even more preferably 0.03 mass% to 3.0 mass%, particularly preferably 0.1 mass% to 2.0 mass%, and even more preferably 0.3 mass% to 2.0 mass%, relative to the total amount of the non-aqueous electrolyte.

[0062] When the additive contains a lithium fluorophosphate compound, the additive preferably further contains one selected from the group consisting of a cyclic carbonate compound (III), a cyclic sulfur-containing ester compound (IV), and a cyclic dicarbonyl compound (V). This allows the nonaqueous electrolyte to better suppress an increase in DC resistance and a decrease in discharge capacity even when the nonaqueous secondary battery is stored at high temperature for a long period of time.

[0063] (Cyclic carbonate compound (III)) The additive preferably contains a cyclic carbonate compound (III).

[0064] By including the cyclic carbonate ester compound (III) in addition to the compound (A), the nonaqueous electrolyte can suppress an increase in the direct current resistance of the nonaqueous secondary battery even during long-term storage at high temperature, more than in a configuration not including the compound (X). This effect is presumably due to the following reasons. After long-term storage at high temperature, the cyclic carbonate compound (III) is easily reductively decomposed by the negative electrode before the nonaqueous electrolyte is reductively decomposed on the negative electrode, forming an SEI film. This suppresses the decomposition of the nonaqueous electrolyte at the negative electrode. As a result, even if the nonaqueous secondary battery is stored at high temperature for a long period of time, the increase in the direct current resistance of the nonaqueous secondary battery can be further suppressed.

[0065] The cyclic carbonate compound (III) is represented by the following formula (III).

[0066] [ka]

[0067] In formula (III), R 11 and R 12 each independently represents a hydrogen atom, a methyl group, an ethyl group, or a propyl group.

[0068] Specific examples of the cyclic carbonate compound (III) include compounds represented by the following formulas (III-1) to (III-7). Hereinafter, the compound represented by formula (III-1) may be referred to as "vinylene carbonate (III-1)".

[0069] [ka]

[0070] The non-aqueous electrolyte is a cyclic carbonate ester. compound When (III) is contained, cyclic carbonate compoundThe content of (III) is preferably 0.10 mass % to 10.0 mass %, more preferably 0.20 mass % to 5.0 mass %, further preferably 0.30 mass % to 3.0 mass %, and particularly preferably 0.30 mass % to 2.0 mass %, based on the total amount of the nonaqueous electrolyte. compound If the content of (III) is within the above range, the decomposition of the non-aqueous solvent on the positive electrode or the negative electrode can be suppressed while the increase in the thickness of the SEI film can be suppressed. As a result, the increase in the direct current resistance of the non-aqueous secondary battery is further suppressed even when it is stored at high temperature for a long period of time. compound If the content of (III) is within the above range, an SEI film having a thickness capable of suppressing decomposition of the nonaqueous solvent in the nonaqueous electrolyte is formed, and as a result, an increase in the direct current resistance of the nonaqueous secondary battery is further suppressed even when the battery is stored at high temperatures for a long period of time.

[0071] (Cyclic sulfur-containing ester compound (IV)) The additive may contain a cyclic sulfur-containing ester compound (IV).

[0072] By containing the cyclic sulfur-containing ester compound (IV) in addition to the compound (A), the nonaqueous electrolyte can suppress an increase in the direct current resistance of the nonaqueous secondary battery even during long-term storage at high temperature, more than in a configuration not containing the compound (X). This effect is presumably due to the following reasons. After long-term storage at high temperature, the cyclic sulfur-containing ester compound (IV) is oxidatively decomposed by the negative electrode before the nonaqueous electrolyte is reductively decomposed on the negative electrode, and is likely to form an SEI film. This suppresses the decomposition of the nonaqueous electrolyte at the positive electrode. As a result, even if the nonaqueous secondary battery is stored at high temperature for a long period of time, the increase in the direct current resistance of the nonaqueous secondary battery can be further suppressed.

[0073] The cyclic sulfur-containing ester compound (IV) is a compound represented by the following formula (IV).

[0074] [ka]

[0075] In formula (IV), R 21 represents an oxygen atom, an alkylene group having 1 to 6 carbon atoms, an alkenylene group having 1 to 6 carbon atoms, or a vinylene group; R 22 represents an alkylene group having 1 to 6 carbon atoms, a group represented by the above formula (iv-1), or a group represented by the above formula (iv-2). * indicates a bonding position. In the above formula (iv-2), R 23 represents a group represented by an alkyl group having 1 to 6 carbon atoms.

[0076] In formula (IV), R 21 is preferably an alkylene group having 1 to 3 carbon atoms, a vinylene group, or an oxygen atom, and more preferably a trimethylene group, a vinylene group, or an oxygen atom.

[0077] In formula (IV), R 22 is preferably a group represented by the above formula (iv-1).

[0078] Specific examples of the cyclic sulfur-containing ester compound (IV) include compounds represented by the following formulas (IV-1) to (IV-7). Hereinafter, the compound represented by formula (IV-1) may be referred to as "cyclic sulfur-containing ester compound (IV-1)", and the compound represented by formula (IV-2) may be referred to as "1,3-propene sultone (IV-2)". The compound represented by formula (IV-3) may be referred to as "4-propyl-1,3,2-dioxathiolane-2,2-dioxide (IV-3)".

[0079] [ka]

[0080] The nonaqueous electrolyte may contain only one type of cyclic sulfur-containing ester compound (IV), or may contain two or more types. When the nonaqueous electrolyte contains two or more types of cyclic sulfur-containing ester compounds (IV), even if the nonaqueous secondary battery is stored at high temperature for a long period of time, the increase in direct current resistance can be suppressed more than when the nonaqueous electrolyte contains one type of cyclic sulfur-containing ester compound (IV), and the decrease in discharge capacity can be suppressed more.

[0081] When the non-aqueous electrolyte contains a cyclic sulfur-containing ester compound (IV), the content of the cyclic sulfur-containing ester compound (IV) is preferably 0.01% by mass to 5.0% by mass, more preferably 0.05% by mass to 3.0% by mass, further preferably 0.10% by mass to 2.0% by mass, and particularly preferably 0.20% by mass to 2.0% by mass, based on the total amount of the non-aqueous electrolyte. If the content of the cyclic sulfur-containing ester compound (IV) is within the above range, the SEI film does not impair the conductivity of lithium ions, and the non-aqueous secondary battery can operate. Furthermore, the battery characteristics of the non-aqueous secondary battery are improved as the SEI film contains a sulfite ester or sulfate ester structure. If the content of the cyclic sulfur-containing ester compound (IV) is within the above range, the SEI film contains a sufficient amount of a sulfite ester or sulfate ester structure. This makes it easier to form a thermally and chemically stable inorganic salt or polymer structure. Therefore, at high temperatures, the SEI film is less susceptible to elution of components that impair the durability of the SEI film, and to deterioration of the SEI film, etc. As a result, the durability of the SEI film and the battery characteristics of the nonaqueous secondary battery are improved.

[0082] (Cyclic dicarbonyl compounds (V)) The additive may contain a cyclic dicarbonyl compound (V).

[0083] By containing the cyclic dicarbonyl compound (V) in addition to the compound (A), the nonaqueous electrolyte can suppress an increase in the direct current resistance of the nonaqueous secondary battery after long-term storage at high temperature more than in a configuration not containing the compound (X). This effect is presumably due to the following reasons. The non-aqueous electrolyte contains a cyclic dicarbonyl compound (V) in addition to the compound (A), so that the SEI film may contain bonds derived from the cyclic dicarbonyl compound (V) in addition to the above-mentioned reaction products. This makes it easier to form a thermally and chemically stable inorganic salt or polymer structure. Therefore, the elution of the components of the SEI film, which impairs the durability of the SEI film, and the deterioration of the SEI film are unlikely to occur at high temperatures. As a result, the decrease in discharge capacity and the increase in direct current resistance of the non-aqueous secondary battery can be further suppressed even in charge-discharge cycles after long-term storage in a high-temperature environment.

[0084] The cyclic dicarbonyl compound (V) is a compound represented by the formula (V).

[0085] [ka]

[0086] In formula (V), M represents an alkali metal, b represents an integer of 1 to 3, m represents an integer of 1 to 4, n represents an integer of 0 to 8, and q represents 0 or 1. 31 represents an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (these groups may contain a substituent or a heteroatom in the structure, and when q is 1 and m is 2 to 4, m R 31 Each of them may be bonded. 32 is a halogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms (these groups may contain a substituent or a heteroatom in the structure, and when n is 2 to 8, n R 32 may be bonded to each other to form a ring. 1 , and Q 2 each independently represents an oxygen atom or a carbon atom.

[0087] In the formula (V), examples of the alkali metal represented by M include lithium, sodium, potassium, etc. Among these, M is preferably lithium. b represents the valence of the anion and the number of cations. b is an integer of 1 to 3. If b is greater than 3, the salt of the anion compound tends to be less soluble in the mixed organic solvent. b is preferably 1. The constants m and n are values ​​related to the number of ligands. Each of m and n can be appropriately adjusted depending on the type of M. n is preferably an integer of 0 to 4. The constant q is 0 or 1. When q is 0, the chelate ring is a five-membered ring, and when q is 1, the chelate ring is a six-membered ring.

[0088] In formula (V), R 31 represents an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms. These alkylene groups, halogenated alkylene groups, arylene groups, or halogenated arylene groups may contain a substituent or a heteroatom in their structure. Specifically, these groups may contain a substituent instead of a hydrogen atom. Examples of the substituent include a halogen atom, a linear or cyclic alkyl group, an aryl group, an alkenyl group, an alkoxy group, an aryloxy group, a sulfonyl group, an amino group, a cyano group, a carbonyl group, an acyl group, an amide group, or a hydroxyl group. Instead of the carbon element of these groups, a nitrogen atom, a sulfur atom, or an oxygen atom may be introduced. When q is 1 and m is 2 to 4, m R 31 may be bonded to each other. An example of such a ligand is ethylenediaminetetraacetic acid.

[0089] In formula (V), R 32 R represents a halogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms. 32The alkyl group, the halogenated alkyl group, the aryl group, or the halogenated aryl group in R 31 Similarly, the structure may contain a substituent or a heteroatom, and when n is 2 to 8, n R 32 may be bonded to each other to form a ring. 32 As the group, an electron-withdrawing group is preferable, and a fluorine atom is particularly preferable.

[0090] Q 1 , and Q 2 each independently represents O or S. That is, the ligand bonds to Y via these heteroatoms.

[0091] Specific examples of the cyclic dicarbonyl compound (V) include compounds represented by the following formula (V-1) or (V-2). Hereinafter, the compound represented by formula (V-1) may be referred to as "lithium bis(oxalato)borate (V-1)".

[0092] [ka]

[0093] When the non-aqueous electrolyte contains a cyclic dicarbonyl compound (V), the content of the cyclic dicarbonyl compound (III) is preferably 0.01% by mass to 10% by mass, more preferably 0.05% by mass to 5.0% by mass, further preferably 0.10% by mass to 3.0% by mass, and particularly preferably 0.10% by mass to 2.0% by mass, based on the total amount of the non-aqueous electrolyte. If the content of the cyclic dicarbonyl compound (V) is within the above range, the SEI film does not impair the conductivity of lithium cations, and the non-aqueous secondary battery can operate. Furthermore, the battery characteristics of the non-aqueous secondary battery are improved as the SEI film contains a boric acid structure. If the content of the cyclic dicarbonyl compound (V) is within the above range, the SEI film contains a sufficient amount of a structure mainly composed of boric acid. This makes it easier to form a thermally and chemically stable inorganic salt or polymer structure. Therefore, the SEI film is less susceptible to elution of components that impair the durability of the SEI film and to deterioration of the SEI film at high temperatures. As a result, the durability of the SEI film is improved. Furthermore, the increase in the direct current resistance of the nonaqueous secondary battery can be further suppressed even when the battery is stored at high temperatures for a long period of time.

[0094] When the additive contains a cyclic dicarbonyl compound (V), the additive preferably further contains at least one kind of cyclic sulfur-containing ester compound (IV), and more preferably further contains two kinds of cyclic sulfur-containing ester compounds (IV), so that the nonaqueous electrolyte can further suppress an increase in direct current resistance and a decrease in discharge capacity even when the nonaqueous secondary battery is stored at high temperature for a long period of time.

[0095] (positive electrode) The nonaqueous secondary battery of the present disclosure includes a positive electrode. The positive electrode contains a positive electrode active material containing a compound (B) represented by the following formula (II). By containing the compound (B), the positive electrode active material of the positive electrode is lithium cobalt oxide (LiCoO 2 ) it is possible to suppress an increase in direct current resistance and increase the discharge capacity of the nonaqueous secondary battery.

[0096] [ka]

[0097] In formula (II), 0.1≦a<1.30, 0.1<1-bc<1.0, 0 <b<0.6、0<c<0.6である。

[0098] The compound (B) is appropriately selected depending on the application of the nonaqueous secondary battery. a is equal to or greater than 0.1 and less than 1.3, preferably from 0.5 to 1.2, more preferably from 0.8 to 1.1, and further preferably from 0.9 to 1.1. (1-bc) is greater than 0.1 and less than 1.0, preferably from 0.2 to 0.9, more preferably from 0.3 to 0.8, and even more preferably from 0.3 to 0.7. The value of b is greater than 0 and less than 0.6, preferably from 0.1 to 0.5, and more preferably from 0.2 to 0.4. c is greater than 0 and less than 0.6, preferably 0.1 to 0.5, and more preferably 0.2 to 0.4.

[0099] Specific examples of the compound (B) include: Li 1.2 Ni 0.15 Co 0.1 Mn 0.55 O 2 (NCM115), Li Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (NCM333), Li Ni 0.4 Co 0.2 Mn 0.4 O 2 (NCM424), Li Ni 0.4 Co 0.3 Mn 0.3 O 2 (NCM433), Li Ni 0.5 Co 0.2 Mn 0.3 O 2 (NCM523), Li Ni0.50 Co 0.25 Mn 0.25 O 2 (NCM502525), Li Ni 0.5 Co 0.3 Mn 0.2 O 2 (NCM532), Li Ni 0.6 Co 0.2 Mn 0.2 O 2 (NCM622), Li Ni 0.7 Co 0.15 Mn 0.15 O 2 (NCM701515), Li Ni 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), Li Ni 0.9 Co 0.5 Mn 0.5 O 2 (NCM900505), Li Ni 0.95 Co 0.25 Mn 0.25 O 2 (NCM952.52.5) ​​etc. The positive electrode may contain one type of compound (B) alone or two or more types of compound (B). Among these, compound (B) preferably includes NCM333, NCM424, NCM433, NCM523, NCM502525, NCM532, NCM622, NCM701515, or NCM811, more preferably includes NCM333, NCM532, NCM622, or NCM811, and even more preferably includes NCM523 or NCM333.

[0100] The positive electrode may contain another positive electrode active material different from the compound (B). Other examples of the positive electrode active material include transition metal oxides or transition metal sulfides, composite oxides made of lithium and transition metals, conductive polymer materials, and the like. Examples of transition metal oxides or transition metal sulfides include MoS 2 , TiS 2 , MnO 2 , V 2 O 5 etc. Examples of composite oxides made of lithium and transition metals include LiCoO 2 , LiMnO 2 , LiMn 2 O 4 , LiNiO 2 , LiNi X Co (1-X) O 2 〔0 <X<1〕、α-NaFeO 2 Li with type crystal structure 1+α Me 1-α O 2 (Me is a transition metal element including Mn, Ni, and Co, 1.0≦(1+α) / (1-α)≦1.6), LiFePO 4 , LiMnPO 4 etc. Examples of the conductive polymer material include polyaniline, polythiophene, polypyrrole, polyacetylene, polyacene, dimercaptothiadiazole, and polyaniline complexes. The other positive electrode active materials may be used alone or in combination of two or more. When the positive electrode active material has insufficient conductivity, the positive electrode can be formed by using the positive electrode active material together with a conductive assistant, such as carbon materials including carbon black, amorphous whiskers, and graphite.

[0101] The positive electrode may include a positive electrode current collector. The material of the positive electrode current collector is not particularly limited, and any known material can be used. Specific examples of the positive electrode current collector include metal materials such as aluminum, aluminum alloys, stainless steel, nickel, titanium, and tantalum; carbon materials such as carbon cloth and carbon paper; and the like.

[0102] The positive electrode may include a positive electrode current collector and a positive electrode active material layer provided on at least a portion of the surface of the positive electrode current collector. The positive electrode active material layer contains at least one positive electrode active material, which preferably contains a composite oxide made of lithium and a transition metal. The content of the composite oxide is preferably 70% by mass to 100% by mass, and more preferably 80% by mass to 100% by mass, based on the total amount of the positive electrode active material layer. The positive electrode active material layer may further contain at least one of the above-mentioned conductive assistants. The positive electrode active material layer may further contain at least one type of binder. Examples of the binder include polyvinyl acetate, polymethyl methacrylate, nitrocellulose, fluororesin, and rubber particles. Examples of the fluororesin include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and vinylidene fluoride-hexafluoropropylene copolymer. Examples of the rubber particles include styrene-butadiene rubber particles and acrylonitrile rubber particles. Among these, fluororesin is preferred from the viewpoint of improving the oxidation resistance of the positive electrode active material layer. The content of the binder is preferably 1% by mass to 20% by mass, and more preferably 1% by mass to 10% by mass, based on the total amount of the positive electrode active material layer.

[0103] (Negative electrode) The nonaqueous secondary battery of the present disclosure includes a negative electrode. The negative electrode may include a negative electrode active material and a negative electrode current collector. The negative electrode active material can be at least one selected from the group consisting of metallic lithium, lithium-containing alloys, metals or alloys capable of being alloyed with lithium, oxides capable of being doped / dedoped with lithium ions, transition metal nitrides capable of being doped / dedoped with lithium ions, and carbon materials capable of being doped / dedoped with lithium ions (which may be used alone or a mixture containing two or more of these may be used). Examples of metals or alloys that can be alloyed with lithium (or lithium ions) include silicon, silicon alloys, tin, tin alloys, etc. The negative electrode active material may be lithium titanate. Among these, from the viewpoint of further improving the formability of the SEI film of the negative electrode and further reducing the DC resistance of the nonaqueous secondary battery at the initial stage and / or after long-term storage at high temperature, the negative electrode active material is preferably a carbon material capable of doping / undoping lithium ions. Examples of such carbon materials include carbon black, activated carbon, graphite materials (artificial graphite, natural graphite), amorphous carbon materials, etc. The carbon material may be in any of the following forms: fibrous, spherical, potato-like, and flake-like.

[0104] Specific examples of amorphous carbon materials include hard carbon, coke, mesocarbon microbeads (MCMB) calcined at 1500° C. or less, and mesophase pitch carbon fiber (MCF). Examples of graphite materials include natural graphite and artificial graphite. Examples of artificial graphite include graphitized MCMB and graphitized MCF. Examples of graphite materials that can be used include those containing boron. Examples of graphite materials that can be used include those coated with metals such as gold, platinum, silver, copper, and tin, those coated with amorphous carbon, and those that are a mixture of amorphous carbon and graphite.

[0105] These carbon materials may be used alone or in combination of two or more. As the carbon material, a carbon material having a (002) plane interplanar spacing d(002) of 0.340 nm or less as measured by X-ray analysis is particularly preferred. As the carbon material, a carbon material having a true density of 1.70 g / cm 3The above-mentioned graphite or a highly crystalline carbon material having properties similar thereto is also preferred. If such a carbon material is used, the energy density of the non-aqueous secondary battery can be further increased.

[0106] The material of the negative electrode current collector in the negative electrode is not particularly limited, and any known material can be used. Specific examples of the negative electrode current collector include metal materials such as copper, nickel, stainless steel, nickel-plated steel, etc. Among these, it is particularly preferable for the negative electrode current collector to contain copper in terms of ease of processing.

[0107] The negative electrode may include a negative electrode current collector and a negative electrode active material layer provided on at least a portion of the surface of the negative electrode current collector. The negative electrode active material layer contains at least one negative electrode active material, which preferably contains the above-mentioned carbon material. From the viewpoints of further improving the formability of the SEI film of the negative electrode and further reducing the DC resistance of the nonaqueous secondary battery at the initial stage and / or after long-term storage at high temperature, the content of the carbon material is preferably 70 mass% to 100 mass%, more preferably 80 mass% to 100 mass%, and even more preferably 90 mass% to 100 mass%, relative to the total amount of the negative electrode active material layer. The negative electrode active material layer may further contain at least one type of binder. The binder is preferably at least one selected from the group consisting of styrene butadiene (SBR) rubber (e.g., SBR latex), acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, carboxymethyl cellulose (CMC), hydroxypropyl methyl cellulose, polyvinyl alcohol, hydroxypropyl cellulose, and diacetyl cellulose. The binder preferably contains SBR latex and carboxymethyl cellulose. The content of the binder in the negative electrode active material layer is preferably 1 mass % to 20 mass %, more preferably 1 mass % to 10 mass %, and even more preferably 1 mass % to 5 mass %, relative to the total amount of the negative electrode active material layer.

[0108] The Si content is preferably 5 mass % or less based on the total amount of the negative electrode. When the Si content is 5 mass % or less, the formability of the SEI film of the negative electrode is further improved, and the DC resistance of the nonaqueous secondary battery at the initial stage and / or after long-term storage at high temperature is further reduced.

[0109] (Separator) The nonaqueous secondary battery of the present disclosure may include a separator disposed between the negative electrode and the positive electrode. The separator is a membrane that electrically insulates the positive electrode from the negative electrode and is permeable to lithium ions, and examples of the separator include a porous membrane and a polymer electrolyte. As the porous membrane, a microporous polymer film is preferably used, and examples of the material include polyolefin, polyimide, polyvinylidene fluoride, polyester, and the like. In particular, the material of the porous membrane preferably contains a porous polyolefin, and specifically, a porous polyethylene film, a porous polypropylene film, or a multi-layer film of a porous polyethylene film and a porous polypropylene film can be exemplified. The porous polyolefin film may be coated with another resin having excellent thermal stability. Examples of the polymer electrolyte include a polymer in which a lithium salt is dissolved, and a polymer swollen with an electrolytic solution. The nonaqueous electrolyte solution of the present disclosure may be used for the purpose of swelling a polymer to obtain a polymer electrolyte.

[0110] [Configuration of non-aqueous secondary battery] The nonaqueous secondary battery of the present disclosure can have various known shapes, such as a cylindrical shape, a coin shape, a square shape, a laminate shape, a film shape, etc. However, the basic structure of the nonaqueous secondary battery is the same regardless of the shape, and the design can be modified according to the purpose.

[0111] An example of the nonaqueous secondary battery of the present disclosure is a laminate type battery. FIG. 1 is a schematic perspective view showing an example of a laminated battery, which is an example of a nonaqueous secondary battery of the present disclosure, and FIG. 2 is a schematic cross-sectional view in the thickness direction of a stacked electrode body accommodated in the laminated battery shown in FIG. The laminated battery 1 includes a laminated exterior body 8. The laminated exterior body 8 contains a nonaqueous electrolyte solution (not shown in FIG. 1) and a laminated electrode body (not shown in FIG. 1) of the present disclosure. The periphery of the laminated exterior body 8 is sealed. In other words, the inside of the laminated exterior body 8 is airtight. The laminated exterior body 8 is made of a material such as aluminum. 2, the laminated electrode body is formed by alternately stacking positive electrode plates 5 and negative electrode plates 6 with separators 7 interposed therebetween. The positive electrode plates 5, negative electrode plates 6, and separators 7 are impregnated with the nonaqueous electrolyte of the present disclosure. Each of the multiple positive electrode plates 5 in the laminated electrode body is electrically connected to a positive electrode terminal 2 via a positive electrode tab (not shown), and a part of this positive electrode terminal 2 protrudes outward from the peripheral edge of the laminated exterior body 8 (see FIG. 1). The portion of the peripheral edge of the laminated exterior body 8 from which the positive electrode terminal 2 protrudes is sealed with an insulating seal 4. Similarly, each of the negative electrode plates 6 in the laminated electrode body is electrically connected to a negative electrode terminal 3 via a negative electrode tab (not shown), and a part of this negative electrode terminal 3 protrudes outward from the peripheral edge of the laminated exterior body 8 (see FIG. 1). The part of the peripheral edge of the laminated exterior body 8 from which the negative electrode terminal 3 protrudes is sealed with an insulating seal 4. In the laminated battery according to the above example, the number of positive electrode plates 5 is five and the number of negative electrode plates 6 is six, and the positive electrode plates 5 and the negative electrode plates 6 are laminated with separators 7 interposed therebetween in an arrangement in which the outermost layers on both sides are negative electrode plates 6. However, it goes without saying that the number and arrangement of positive and negative electrode plates in the laminated battery are not limited to this example, and various modifications may be made.

[0112] Another example of the nonaqueous secondary battery of the present disclosure is a coin-type battery. FIG. 3 is a schematic perspective view showing an example of a coin-type battery, which is another example of the nonaqueous secondary battery of the present disclosure. 3, a disk-shaped negative electrode 12, a separator 15 filled with a non-aqueous electrolyte, a disk-shaped positive electrode 11, and, if necessary, spacer plates 17, 18 made of stainless steel, aluminum, or the like are stacked in this order and housed between a positive electrode can 13 (hereinafter also referred to as a "battery can") and a sealing plate 14 (hereinafter also referred to as a "battery can lid"). The positive electrode can 13 and the sealing plate 14 are crimped and sealed with a gasket 16 interposed therebetween. In this example, the nonaqueous electrolyte of the present disclosure is used as the nonaqueous electrolyte injected into separator 15 .

[0113] The use of the nonaqueous secondary battery of the present disclosure is not particularly limited, and the battery can be used in various known applications. For example, the nonaqueous secondary battery can be widely used in electric vehicles, notebook computers, mobile computers, mobile phones, headphone stereos, video movie players, liquid crystal televisions, handy cleaners, electronic organizers, calculators, radios, backup power sources, motors, lighting equipment, game machines, clocks, power tools, cameras, and other small portable devices and large devices. The electric vehicle includes an electric four-wheel vehicle or an electric two-wheel vehicle. The electric four-wheel vehicle includes an electric vehicle (EV), a plug-in hybrid electric vehicle (PHEV), or a hybrid vehicle (HV). The electric two-wheel vehicle includes an electric motorcycle or an electrically assisted bicycle.

[0114] [Method for manufacturing non-aqueous secondary battery] The method for producing a nonaqueous secondary battery according to the present disclosure includes a preparation step, which will be described later, and an aging step, which will be described later, thereby obtaining a nonaqueous secondary battery.

[0115] (preparation process) In the preparation step, a non-aqueous secondary battery precursor is prepared.

[0116] The nonaqueous secondary battery precursor includes a nonaqueous electrolyte solution containing the compound (A) represented by the above formula (I), a positive electrode containing the compound (B) represented by the above formula (II), and a negative electrode. The content of the compound (A) is more than 0 mass % and less than 1.0 mass % with respect to the total amount of the nonaqueous electrolyte solution.

[0117] The structure of the nonaqueous secondary battery precursor is the same as that of the nonaqueous secondary battery except that the SEI film is not formed, and therefore a description of the structure of the nonaqueous secondary battery precursor is omitted.

[0118] The method for preparing the nonaqueous secondary battery precursor is not particularly limited, and the nonaqueous secondary battery precursor may be assembled by a known method.

[0119] (Aging process) In the aging step, the nonaqueous secondary battery precursor is charged or discharged (hereinafter referred to as "aging treatment"). This forms an SEI film. That is, a nonaqueous secondary battery is obtained.

[0120] The aging treatment includes charging and discharging the nonaqueous secondary battery precursor in an environment of 25° C. or higher and 70° C. or lower. In detail, the aging treatment includes a first charging phase, a first holding phase, a second charging phase, a second holding phase, and a charge / discharge phase.

[0121] In the first charging phase, the nonaqueous secondary battery precursor is charged in an environment of 25° C. or higher and 70° C. or lower. In the first holding phase, the nonaqueous secondary battery precursor after the first charging phase is held in an environment of 25° C. or higher and 70° C. or lower. In the second charging phase, the nonaqueous secondary battery precursor after the first holding phase is charged in an environment of 25° C. or higher and 70° C. or lower. In the second holding phase, the nonaqueous secondary battery precursor after the second charging phase is held in an environment of 25° C. or higher and 70° C. or lower. In the charge / discharge phase, the nonaqueous secondary battery precursor after the second holding phase is subjected to a combination of charging and discharging one or more times in an environment of 25° C. or higher and 70° C. or lower.

[0122] The nonaqueous secondary battery obtained by the method for producing a nonaqueous secondary battery according to the present disclosure exhibits more effective effects of suppressing an increase in direct current resistance and a decrease in discharge capacity than a configuration not containing compound (A), even when stored at high temperature for a long period of time. EXAMPLES

[0123] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to examples. Note that the present disclosure is not limited to the description of these examples.

[0124] Example 1-1 A non-aqueous secondary battery precursor was prepared as follows.

[0125] <Preparation of non-aqueous electrolyte> Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a ratio of EC:DMC:EMC=30:35:35 (volume ratio) to obtain a mixed solvent as a non-aqueous solvent. LiPF as electrolyte 6 was dissolved in the resulting mixed solvent so that the final concentration in the non-aqueous electrolyte solution was 1 mol / L to obtain an electrolyte solution. Hereinafter, the resulting electrolyte solution is referred to as the "base electrolyte solution."

[0126] As compound (A), acesulfame Li shown in (I-1) below was used. Acesulfame Li was added to the base electrolyte so that the content relative to the total amount of the finally obtained non-aqueous electrolyte was the content (mass %) shown in Table 1. In this way, a non-aqueous electrolyte was obtained.

[0127] [ka]

[0128] <Preparation of positive electrode> LiNi as the positive electrode active material 0.5 Co 0.2 Mn 0.3 O 2A mixture was obtained by adding 94% by mass of ZnO, 3% by mass of carbon black as a conductive assistant, and 3% by mass of polyvinylidene fluoride (PVdF) as a binder. The mixture was dispersed in an N-methylpyrrolidone solvent to obtain a positive electrode mixture slurry. An aluminum foil having a thickness of 20 μm was prepared as a positive electrode current collector. The obtained positive electrode mixture slurry was applied onto an aluminum foil, dried, and then rolled with 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.

[0129] <Preparation of negative electrode> A negative electrode mixture slurry was obtained by mixing 96 mass% natural graphite as a negative electrode active material, 1 mass% carbon black as a conductive additive, 1 mass% solids of sodium carboxymethylcellulose dispersed in pure water as a thickener, and 2 mass% solids of styrene-butadiene rubber (SBR) dispersed in pure water as a binder. A copper foil having a thickness of 10 μm was prepared as a negative electrode current collector. The obtained negative electrode mixture slurry was applied onto a copper foil, dried, and then rolled with a press to obtain a sheet-shaped negative electrode. The obtained negative electrode was composed of a negative electrode current collector and a negative electrode active material layer.

[0130] <Preparing the separator> As a separator, a porous polyethylene film was prepared.

[0131] <Making a coin-type battery> The negative electrode was punched out into a disk shape with a diameter of 14 mm, the positive electrode into a disk shape with a diameter of 13 mm, and the separator into a disk shape with a diameter of 17 mm, thereby obtaining a coin-shaped negative electrode, a coin-shaped positive electrode, and a coin-shaped separator. 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 size). Next, 20 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 can lid was crimped via a polypropylene gasket to seal the battery. In this manner, a coin-shaped nonaqueous secondary battery precursor was obtained having the structure shown in Fig. 3. The coin-shaped nonaqueous secondary battery precursor had a diameter of 20 mm and a height of 3.2 mm.

[0132] [Examples 1-2 to 2-4, Comparative Examples 1-1 to 2-1] A coin-type nonaqueous secondary battery precursor was obtained in the same manner as in Example 1-1, except that the type of compound (B), the type and content of compound (A), and the type and content of compound (X) were changed as shown in Table 1. The compounds used in Examples 1-2 to 2-4 and Comparative Examples 1-1 to 2-1 are represented by the following formulas. Specifically, acesulfame K is represented by the following formula (I-2). Vinylene carbonate (III-1) is represented by the following formula (III-1). Cyclic sulfur-containing ester compound (IV-1) is represented by the following formula (IV-1). 1,3-propene sultone (IV-2) is represented by the following formula (IV-2). 4-propyl-1,3,2-dioxathiolane-2,2-dioxide (IV-3) is represented by the following formula (IV-3). Lithium bis(oxalato)borate (V-1) is represented by the following formula (V-1).

[0133] [ka]

[0134] [Evaluation test] The obtained nonaqueous secondary battery precursor was subjected to the aging treatment described below to obtain a first battery. The obtained first battery was subjected to the initial charge / discharge treatment described below to obtain a second battery. The obtained second battery was subjected to the treatment described below for evaluating DC resistance to obtain a third battery. The obtained third battery was subjected to a high-temperature storage treatment to obtain a fourth battery. The obtained fourth battery was subjected to the later charge / discharge treatment described below to obtain a fifth battery. The resistance increase rate and capacity retention rate of the resulting first to fifth batteries were measured by the following measurement methods. The measurement results are shown in Table 1. Furthermore, in the above-mentioned <Preparation of Non-aqueous Electrolyte>, the injection property was evaluated by the following evaluation method. The evaluation results are shown in Table 1.

[0135] As described above, it was not possible to prepare a nonaqueous secondary battery precursor in Comparative Examples 1-2 to 1-11, and therefore it was not possible to evaluate the resistance increase rate and capacity retention rate in Comparative Examples 1-2 to 1-11.

[0136] <Aging treatment> The nonaqueous secondary battery precursor was subjected to the following aging treatment to obtain a first battery. The nonaqueous secondary battery precursor was charged at a temperature range of 25 to 60°C with a cut-off voltage range of 1.5V to 3.5V, and then rested for 5 to 50 hours. Next, the nonaqueous secondary battery precursor was charged at a temperature range of 25 to 60°C with a cut-off voltage range of 3.5V to 4.2V, and held for 5 to 50 hours. Next, the nonaqueous secondary battery precursor was charged to 4.2V at a temperature range of 25 to 60°C, and then discharged to 2.5V. This produced a first battery.

[0137] <Initial charge / discharge process> The first battery was subjected to the following initial charge / discharge treatment to obtain a second battery. The first battery was kept in a temperature environment of 25°C for 12 hours. Next, the first battery was charged at a constant current and constant voltage (0.2C-CCCV) at a charge rate of 0.2C to 4.2V (SOC (State Of Charge): 100%), then rested for 30 minutes, and then discharged at a constant current (0.2C-CC) at a discharge rate of 0.2C to 2.5V. This was repeated for three cycles to stabilize the battery. Thereafter, the first battery was charged at a constant current and constant voltage (0.5C-CCCV) at a charge rate of 0.2C to 4.2V, then rested for 30 minutes, and then discharged at a constant current (1C-CC) at a discharge rate of 1C to 2.5V. This produced a second battery.

[0138] <Processing for DC resistance evaluation> The second battery was subjected to the following treatment for evaluating DC resistance to obtain a third battery. The process for evaluating DC resistance was carried out in a temperature environment of 25° C. The second battery was CC discharged to 2.5 V at a discharge rate of 0.2 C, and CCCV charged to 3.7 V at a charge rate of 0.2 C. "CCCV charging" means charging at a constant current and constant voltage. Next, the second battery was subjected to CC10s discharge at a discharge rate of 0.2 C and CC10s charging at a charge rate of 0.2 C. "CC10s discharge" means discharging at a constant current for 10 seconds. "CC10s charging" means charging at a constant current for 10 seconds. Next, the second battery was subjected to CC10s discharge at a discharge rate of 0.5C and CC25s charging at a charge rate of 0.2C. Next, the second battery was subjected to CC10s discharge at a discharge rate of 1C and CC50s charging at a charge rate of 0.2C. Next, the second battery was subjected to CC10s discharge at a discharge rate of 2C and CC100s charging at a charge rate of 0.2C. This produced a third battery.

[0139] <High temperature preservation treatment> The third battery was subjected to the following high-temperature storage treatment to obtain a fourth battery. The third battery was charged at a constant current of 0.2 C to 4.2 V in a temperature environment of 25° C. The charged battery was then left to stand for 14 days in an atmosphere of 60° C. Thus, a fourth battery was obtained.

[0140] <Late-stage charge / discharge treatment> The fourth battery was subjected to the following later charge-discharge treatment to obtain a fifth battery. The fourth battery was allowed to cool in a temperature environment of 25°C, and was then subjected to a first discharge, a first charge, and a second discharge. The first discharge refers to a constant current discharge (1C-CC) to 2.5V at a discharge rate of 1C. The first charge refers to a constant current constant voltage charge (0.2C-CCCV) to 4.2V at a charge rate of 0.2C. The second discharge refers to a constant current discharge (1C-CC) to 2.5V at a discharge rate of 1C. In this way, the fifth battery was obtained.

[0141] <Method of measuring capacity retention rate> The positive electrode active materials used in Examples 1-1 to 1-19 and Comparative Example 1-1 are different from those used in Examples 2-1 to 2-4 and Comparative Example 2-1. Therefore, as described below, the capacity retention rates of Examples 1-1 to 1-9 were determined based on Comparative Example 1-1, and the capacity retention rates of Examples 2-1 to 2-4 were determined based on Comparative Example 2-1.

[0142] (Examples 1-1 to 1-19) For Examples 1-1 to 1-19, the relative value of the discharge capacity of the fourth battery of each Example to the discharge capacity of the fourth battery of Comparative Example 1-1 was defined as the "capacity maintenance rate [%]" as shown in the following formula (X1A). The discharge capacity indicates the capacity obtained when the second discharge was performed in the above-mentioned later charge-discharge treatment.

[0143] Capacity retention rate [relative value; %] = (discharge capacity of the fourth battery [mAh / g] / discharge capacity of the fourth battery of Comparative Example 1-1 [mAh / g]) × 100 ... (X1A)

[0144] (Examples 2-1 to 2-4) For Examples 2-1 to 2-4, the relative value of the discharge capacity of the fourth battery of each Example to the discharge capacity of the fourth battery of Comparative Example 2-1 was defined as the "capacity maintenance rate [%]" as shown in the following formula (X1B).

[0145] Capacity retention rate [relative value; %] = (discharge capacity of the fourth battery [mAh / g] / discharge capacity of the fourth battery of Comparative Example 2-1 [mAh / g]) × 100 ... (X1B)

[0146] <Method for measuring resistance increase rate> The positive electrode active material used in Examples 1-1 to 1-19 and Comparative Example 1-1 is different from that used in Examples 2-1 to 2-4 and Comparative Example 2-1. Therefore, as described below, the resistance increase rates of Examples 1-1 to 1-19 were determined based on Comparative Example 1-1, and the resistance increase rates of Examples 2-1 to 2-4 were determined based on Comparative Example 2-1.

[0147] (Examples 1-1 to 1-19) For Examples 1-1 to 1-19, the relative value of the resistance increase rate of each Example to the resistance increase rate of Comparative Example 1-1 was defined as the "resistance increase rate [%]" as shown in the following formula (X2A).

[0148] Resistance increase rate [relative value; %] = (resistance increase rate / resistance increase rate of comparative example 1-1) × 100 ... (X2A)

[0149] In formula (X2A), the resistance increase rate is the DC resistance (Ω) of the fourth battery divided by the DC resistance (Ω) of the second battery.

[0150] The DC resistance (Ω) of the fourth battery was measured by the following method. The fourth battery was subjected to a DC resistance evaluation process similar to the DC resistance evaluation process described above. The DC resistance (Ω) of the fourth battery was calculated based on the voltage drop (=voltage before the start of discharge-voltage 10 seconds after the start of discharge) and each current value (i.e., each current value corresponding to the discharge rates of 0.2C to 1C) due to "CC10s discharge" at each of the discharge rates of 0.2C to 1C.

[0151] The DC resistance (Ω) of the second battery was measured in the same manner as the DC resistance (Ω) of the fourth battery.

[0152] (Examples 2-1 to 2-4) For Examples 2-1 to 2-4, the relative value of the resistance increase rate of each Example to the resistance increase rate of Comparative Example 2-1 was defined as the "resistance increase rate [%]" as shown in the following formula (X2B).

[0153] Resistance increase rate [relative value; %] = (resistance increase rate / resistance increase rate of comparative example 2-1) × 100 ... (X2B)

[0154] In formula (X2B), the resistance increase rate is obtained by dividing the DC resistance (Ω) of the fourth battery by the DC resistance (Ω) of the second battery.

[0155] <Injectability evaluation> In the above <Preparation of non-aqueous electrolyte>, whether or not the compound (A) was dissolved in the base electrolyte was visually observed. Based on the visual observation results, the pourability was evaluated according to the following criteria. The evaluation criteria are as follows. The evaluation results are shown in Table 1.

[0156] A: Compound (A) was completely dissolved in the basic electrolyte. B: Compound (A) was not completely dissolved in the basic electrolyte, and insoluble components were confirmed.

[0157] [Table 1]

[0158] In Table 1, "content of compound (A)" indicates the content [mass%] of compound (A) relative to the total amount of the finally obtained non-aqueous electrolyte. "content of compound (X)" indicates the content [mass%] of compound (X) relative to the total amount of the finally obtained non-aqueous electrolyte. In Table 1, in the section on compound (B), "NCM523" is "LiNi 0.5 Co 0.2 Mn 0.3 O 2 " and "NCM333" is "LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 ". In Table 1, in the column for compound (X), "(III-1)" indicates "vinylene carbonate (III-1)", "(V-1)" indicates "lithium bis(oxalato)borate (V-1)", "(IV-1)" indicates "cyclic sulfur-containing ester compound (IV-1)", "(IV-2)" indicates "1,3-propene sultone (IV-2)", and "(IV-3)" indicates "4-propyl-1,3,2-dioxathiolane-2,2-dioxide (IV-3)". In Table 1, "-" in the non-aqueous secondary battery column indicates that the corresponding component is not contained, and "-" in the evaluation result column indicates that the evaluation could not be performed.

[0159] The above relative value of the DC resistance of the fifth battery after the high-temperature storage test corresponds to the increase rate (%) of DC resistance due to storage in an atmosphere at 60° C. (hereinafter, also simply referred to as the “resistance increase rate”). The increase rate referred to here is an increase rate in a mode in which neither increase nor decrease is expressed as 100%, an increase is expressed as more than 100%, and a decrease is expressed as less than 100%. The reason for focusing on the rate of increase in resistance is that, although a low resistance value itself is an important performance factor in battery performance, reducing the rate of increase in resistance due to deterioration during storage is also an extremely important performance factor.

[0160] In Comparative Examples 1-2 to 1-11, the content of acesulfame Li relative to the total amount of the finally obtained nonaqueous electrolyte was 1.0 mass % Acesulfame Li or Acesulfame K was added to the basic electrolyte solution so as to achieve the above. Therefore, Acesulfame Li or Acesulfame K was not completely dissolved in the basic electrolyte solution. Therefore, in Comparative Examples 1-2 to 1-11, it was not possible to prepare a nonaqueous secondary battery precursor.

[0161] On the other hand, in Examples 1-1 to 1-19, a non-aqueous electrolyte solution, a positive electrode, and a negative electrode are provided. The non-aqueous electrolyte solution contains acesulfame Li or acesulfame K. The positive electrode contains Li(Ni 0.5 Co 0.2 Mn 0.3O 2 ) or Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 ). The content of acesulfame Li was more than 0 mass % and less than 1.0 mass % with respect to the total amount of the non-aqueous electrolyte. Therefore, acesulfame Li or acesulfame K was completely dissolved in the basic electrolyte. The resistance increase rate of Examples 1-1 to 1-19 was 97% or less, and the capacity retention rate was 110% or more. As a result, it was found that the non-aqueous secondary batteries of Examples 1-1 to 1-19 had an acesulfame compound dissolved in the non-aqueous electrolyte and suppressed an increase in DC resistance and a decrease in discharge capacity even when stored for a long period of time in a fully charged state under a high-temperature environment.

[0162] Comparing Example 1-1 with Example 1-3, and comparing Example 1-2 with Example 1-4, it was found that when the content of acesulfame Li or acesulfame K is 0.3 mass% or more relative to the total amount of the nonaqueous electrolyte, the increase in DC resistance and the decrease in discharge capacity of the nonaqueous secondary battery are more suppressed even when the battery is stored for a long period of time in a fully charged state in a high-temperature environment.

[0163] Comparing Examples 1-5 to 1-9 with Examples 1-1 to 1-4, it was found that when the nonaqueous electrolyte solution contains compound (X), the increase in DC resistance of the nonaqueous secondary battery tends to be more suppressed even when the battery is stored for a long period of time in a fully charged state under a high-temperature environment.

[0164] In particular, comparison with Examples 1-8, 1-5 to 1-7, and 1-9 reveals that when the nonaqueous electrolyte contains "cyclic sulfur-containing ester compound (IV-1)," the increase in DC resistance of the nonaqueous secondary battery is further suppressed even when the battery is stored for a long period of time in a fully charged state under a high-temperature environment.

[0165] Comparing Examples 1-10 to 1-19 with Examples 1-1 to 1-9, it was found that when the nonaqueous electrolyte solution contains two or more types of "compound (X)," the decrease in discharge capacity is more suppressed and the increase in DC resistance tends to be suppressed, even when the nonaqueous secondary battery is stored for a long period of time in a fully charged state in a high-temperature environment, compared to when the nonaqueous electrolyte solution does not contain "compound (X)" or when the nonaqueous electrolyte solution contains one type of "compound (X)."

[0166] Among Examples 1-10 to 1-19, in Examples 1-10 to 1-11 and Examples 1-13 to 1-15, the nonaqueous electrolyte contains lithium difluorophosphate and one selected from vinylene carbonate (III-1), cyclic sulfur-containing ester compound (IV-1), 4-propyl-1,3,2-dioxathiolane-2,2-dioxide (IV-3) and lithium bis(oxalato)borate (V-1). Non-aqueous secondary battery It was found that even when the battery was stored in a fully charged state in a high-temperature environment for a long period of time, the increase in DC resistance was relatively well suppressed and the decrease in discharge capacity was relatively well suppressed.

[0167] Among Examples 1-10 to 1-19, in Examples 1-16 to 1-19, the nonaqueous electrolyte contains a cyclic sulfur-containing ester compound (IV-1) and lithium bis(oxalato)borate (V-1). Non-aqueous secondary battery It was found that the decrease in discharge capacity was relatively well suppressed even when the battery was stored for a long period of time in a high-temperature environment in a fully charged state. Among Examples 1-16 to 1-19, in Example 1-18, the nonaqueous electrolyte contains 1,3-propene sultone (IV-2) in addition to the cyclic sulfur-containing ester compound (IV-1) and lithium bis(oxalato)borate (V-1). Non-aqueous secondary battery It was found that the increase in DC resistance was more suppressed even when the battery was stored for a long period of time in a fully charged state in a high-temperature environment. Among Examples 1-10 to 1-19, in Example 1-12, the nonaqueous electrolyte contains lithium difluorophosphate, a cyclic sulfur-containing ester compound (IV-1) and lithium bis(oxalato)borate (V-1). Non-aqueous secondary battery It was found that the increase in DC resistance was effectively suppressed even when the battery was stored for a long period of time in a high-temperature environment in a fully charged state.

[0168] Comparing Examples 1-18 and 1-19 with Example 1-16, it was found that when the nonaqueous electrolyte solution contained two or more types of "cyclic sulfur-containing ester compound (IV-1)", the increase in DC resistance of the nonaqueous secondary battery was further suppressed even when the battery was stored for a long period of time in a fully charged state under a high-temperature environment.

[0169] In Examples 2-1 and 2-2, a non-aqueous electrolyte solution, a positive electrode, and a negative electrode are provided. The non-aqueous electrolyte solution contains acesulfame Li or acesulfame K. The positive electrode contains Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 ). The content of acesulfame Li or acesulfame K was more than 0 mass % and 1.0 mass % with respect to the total amount of the nonaqueous electrolyte. Therefore, acesulfame Li or acesulfame K was completely dissolved in the basic electrolyte. The resistance increase rate of Examples 2-1 and 2-2 was 67% or less, and the capacity maintenance rate was 110% or more. As a result, it was found that the nonaqueous secondary batteries of Examples 2-1 and 2-2 suppressed an increase in DC resistance and a decrease in discharge capacity even when stored for a long period of time in a fully charged state in a high-temperature environment.

[0170] Comparing Example 2-1 with Example 2-3, and comparing Example 2-2 with Example 2-4, it was found that when the content of acesulfame Li or acesulfame K is 0.3 mass% or more relative to the total amount of the nonaqueous electrolyte, the increase in DC resistance and the decrease in discharge capacity of the nonaqueous secondary battery are more suppressed even when the battery is stored for a long period of time in a fully charged state in a high-temperature environment.

[0171] The disclosure of Japanese Patent Application No. 2021-044153, filed on March 17, 2021, is incorporated by reference in its entirety into this specification. All publications, patent applications, and standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A non-aqueous electrolyte solution containing a compound (A) represented by the following formula (I); A positive electrode including a positive electrode active material including a compound (B) represented by the following formula (II); A negative electrode; a separator disposed between the positive electrode and the negative electrode; It consists of: the positive electrode comprises a positive electrode current collector and a positive electrode active material layer provided on at least a part of a surface of the positive electrode current collector and containing the positive electrode active material; the negative electrode includes a negative electrode current collector and a negative electrode active material layer provided on at least a portion of a surface of the negative electrode current collector, The content of the compound (A) is more than 0 mass % and less than 1.0 mass % with respect to the total amount of the nonaqueous electrolyte. 【Chemistry 1】 (In formula (I), X ＋ represents one selected from a hydrogen ion, a lithium ion, a sodium ion, and a potassium ion. 【Chemistry 2】 (In formula (II), 0.1≦a<1.3, 0.1<1-b-c<1.0, 0<b<0.6, and 0<c<0.6.)

2. The compound (A) is ＋ The non-aqueous secondary battery of claim 1 , comprising a compound in which is a lithium ion.

3. The compound (A) is ＋ The nonaqueous secondary battery according to claim 1 , comprising a compound in which is a potassium ion.

4. 4. The nonaqueous secondary battery according to claim 1, wherein the nonaqueous electrolyte contains a nonaqueous solvent containing ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.

5. The compound (B) is LiNi ０．５ Co ０．２ Mn ０．３ O ２ or a compound represented by LiNi １／３ Co １／３ Mn １／３ O ２ The non-aqueous secondary battery according to any one of claims 1 to 4, comprising a compound represented by the formula:

6. The nonaqueous secondary battery according to any one of claims 1 to 5, wherein the nonaqueous electrolyte does not contain propylene carbonate.

7. The non-aqueous electrolyte contains a compound (X), The compound (X) is At least one compound selected from the group consisting of lithium monofluorophosphate and lithium difluorophosphate; A compound represented by the following formula (III), A compound represented by the following formula (IV), A compound represented by the following formula (V): The nonaqueous secondary battery according to any one of claims 1 to 6, wherein the nonaqueous secondary battery is at least one selected from the group consisting of: 【Chemistry 3】 [In formula (III), R １１ and R １２ are each independently a hydrogen atom, a methyl group, an ethyl group, or a propyl group. In formula (IV), R ２１ represents an oxygen atom, an alkylene group having 1 to 6 carbon atoms, an alkenylene group having 1 to 6 carbon atoms, or a vinylene group; R ２２ represents an alkylene group having 1 to 6 carbon atoms, a group represented by the above formula (iv-1), or a group represented by the above formula (iv-2). * indicates a bonding position. In the above formula (iv-2), R ２３ represents a group represented by an alkyl group having 1 to 6 carbon atoms. In formula (V), M represents an alkali metal, b represents an integer of 1 to 3, m represents an integer of 1 to 4, n represents an integer of 0 to 8, and q represents 0 or 1. ３１ represents an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (these groups may contain a substituent or a heteroatom in the structure, and when q is 1 and m is 2 to 4, m R ３１ may be bonded to each other; R ３２ is a halogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms (these groups may contain a substituent or a heteroatom in the structure, and when n is 2 to 8, n R ３２ may be bonded to each other to form a ring; １ , and Q ２ each independently represents an oxygen atom or a carbon atom.

8. A preparation step of preparing a non-aqueous secondary battery precursor; an aging step of charging and discharging the nonaqueous secondary battery precursor, The nonaqueous secondary battery precursor is A non-aqueous electrolyte solution containing a compound (A) represented by the following formula (I); A positive electrode including a positive electrode active material including a compound (B) represented by the following formula (II); A negative electrode; a separator disposed between the positive electrode and the negative electrode; It consists of: the positive electrode comprises a positive electrode current collector and a positive electrode active material layer provided on at least a part of a surface of the positive electrode current collector and containing the positive electrode active material; the negative electrode includes a negative electrode current collector and a negative electrode active material layer provided on at least a portion of a surface of the negative electrode current collector, a content of the compound (A) is more than 0 mass % and less than 1.0 mass % with respect to a total amount of the nonaqueous electrolyte solution. 【Chemistry 4】 (In formula (I), X ＋ represents one selected from a hydrogen ion, a lithium ion, a sodium ion, and a potassium ion. 【Chemistry 5】 (In formula (II), 0.1≦a<1.3, 0.1<1-b-c<1.0, 0<b<0.6, and 0<c<0.6.)

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