Non-aqueous electrolyte, battery pack, and method for manufacturing battery pack

Abstract

This invention provides a high-capacity battery pack that eliminates battery balance deviations, prevents the precipitation of poorly soluble redox shuttles, suppresses overcharge degradation, improves battery yield, and ensures stable charge-discharge cycles. The battery pack is characterized by comprising a non-aqueous secondary battery, which includes a positive electrode, a negative electrode, and a non-aqueous electrolyte containing an electrolyte salt and a non-aqueous solvent. The battery pack is constructed by connecting one or more modules consisting of two or more non-aqueous secondary batteries connected in series in parallel, or by connecting two or more modules consisting of two or more non-aqueous secondary batteries connected in parallel in series in series. The ratio of the maximum capacity (B) to the minimum capacity (A) of each non-aqueous secondary battery constituting the module is 1.00 < B / A < 2.00, and the non-aqueous electrolyte contains a redox shuttle with a reversible redox potential at a potential higher than the positive electrode potential when fully charged.

Description

Technical Field

[0001] This invention relates to non-aqueous electrolytes, battery packs, and methods for manufacturing battery packs. Background Technology

[0002] The use of lithium-ion batteries in mobile / IT applications has undergone significant changes in the global trend of automotive electrification. While individual differences between individual cells are not a major issue when using single cells, they can become a cause of localized overcharging / over-discharging due to imbalances in modular applications, thus becoming a critical problem. Therefore, it is necessary to select cells with no individual differences for modularization.

[0003] On the other hand, from a yield perspective, the screening process used to reduce individual cell variations is extremely inefficient. Current electric vehicles avoid the effects of balance deviations by setting the full charge voltage to a lower level than that used in residential applications, but if the ability to automatically adjust balance deviations within the module could be provided, it would contribute to both productivity and functionality.

[0004] Furthermore, as mechanisms to suppress overcharging of lithium-ion batteries, methods based on chemical reactions and methods based on electronic circuits have been proposed, with the latter being the primary approach in practical applications. However, the electronic circuit-based method has not only become increasingly expensive with the advancement of multi-cell technology, but has also created various constraints in product design.

[0005] Therefore, techniques for suppressing overcharging through chemical reactions are being developed. One approach, for non-aqueous electrolytes, involves adding a redox reagent with a redox potential equivalent to the overcharging potential. According to this method, when the redox reagent exhibits good reversible reactivity, it creates a suppression effect that consumes the overcharging current by oscillating between the positive and negative electrodes.

[0006] Such redox agents are called redox shuttles. If the safety devices of lithium-ion batteries can be simplified by including redox shuttles in non-aqueous electrolytes, a lower-cost battery system than one with an electronic circuit-based overcharge suppression mechanism can be achieved, while also suppressing the additional power consumption caused by the electronic circuit itself, making it very useful.

[0007] For example, the following patent documents 1 and 2 report that, for lithium-ion batteries of 4V or higher, aromatic compounds with a methoxy group incorporated into the benzene ring act as redox shuttles.

[0008] In addition, the following patent document 3 reports that by using acetonitrile as a non-aqueous solvent, it can also act as a redox shuttle when charging at high current density, thereby suppressing overcharging.

[0009] Furthermore, Patent Document 4 below reports a multi-cell lithium-ion battery using a non-aqueous electrolyte containing a redox shuttle.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Application Publication No. 7-302614

[0013] Patent Document 2: Japanese Patent Application Publication No. 9-17447

[0014] Patent Document 3: Japanese Patent Application Publication No. 2013-232326

[0015] Patent Document 4: Japanese Patent Publication No. 2015-520935 Summary of the Invention

[0016] The problem the invention aims to solve

[0017] However, the redox shuttle in patent documents 1 and 2 limits the diffusion rate. In the case of conventional non-aqueous electrolytes, the diffusion within the electrode layer cannot reach a practical level. Except for the unrealistic condition of charging non-aqueous secondary batteries with extremely low current density, it is difficult to achieve overcharge suppression effect. This is a common problem of redox shuttles.

[0018] In addition, the inventors of this application previously disclosed a non-aqueous solvent containing acetonitrile in Patent Document 3, but did not specifically describe the battery pack.

[0019] Patent document 4 describes the general structure of the battery pack and provides an equivalent description of the battery materials, but does not describe any understanding of the aforementioned problems or any means of solving them.

[0020] The present invention was made in view of the above circumstances, and its object is to provide a non-aqueous electrolyte and a high-capacity battery pack that can eliminate balance deviations between two or more non-aqueous secondary batteries when charging at high current density and achieve stable charge-discharge cycles, even when the initial capacities of the non-aqueous secondary batteries constituting the battery pack are inconsistent. Furthermore, the object is to provide a non-aqueous electrolyte and a battery pack that can eliminate capacity deviations between two or more non-aqueous secondary batteries even at low and high temperatures.

[0021] Solution for solving the problem

[0022] To address the aforementioned issues, the inventors conducted in-depth research and repeated experiments. The results showed that a battery pack containing a specific non-aqueous electrolyte, positive electrode, and negative electrode is independent of the individual differences of each non-aqueous secondary battery. The balance deviation between two or more non-aqueous secondary batteries within the module is automatically eliminated, contributing to both productivity and functionality. This led to the completion of the present invention.

[0023] That is, the present invention is as follows.

[0024] [1] A battery pack, characterized in that it comprises a non-aqueous secondary battery, the non-aqueous secondary battery comprising: a positive electrode, a negative electrode, and a non-aqueous electrolyte containing an electrolyte salt and a non-aqueous solvent.

[0025] The battery pack is constructed by connecting one or more modules consisting of two or more non-aqueous secondary batteries connected in series in parallel, or by connecting two or more modules consisting of two or more non-aqueous secondary batteries connected in parallel in series in series.

[0026] The ratio of the maximum capacity (B) to the minimum capacity (A) of each non-aqueous secondary battery constituting this module is 1.00 < B / A < 2.00, and

[0027] This non-aqueous electrolyte contains a redox shuttle that has a reversible redox potential at a potential higher than the positive electrode potential when fully charged.

[0028] [2] According to the battery pack described in [1] above, wherein the aforementioned redox shuttle comprises a compound represented by the following general formula (1),

[0029]

[0030] {In equation (1), R} 1 R 2 R 3 R 4 R 5 and R 6 The substituents shown are independently hydrogen atoms, halogen atoms, aryl groups, alkyl groups having 1 to 4 carbon atoms, fluoro-substituted alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms, wherein two or more of these substituents are alkoxy groups having 1 to 4 carbon atoms or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms.

[0031] [3] The battery pack according to [2] above, wherein the compound represented by the above general formula (1) is contained in 0.1 to 20% by mass relative to the total amount of the above non-aqueous electrolyte.

[0032] [4] The battery pack according to any one of [1] to [3] above, wherein the capacity of each of the aforementioned non-aqueous secondary batteries constituting the aforementioned module is 1 mAh or more and 100 Ah or less, and the ratio of the maximum capacity (B) of each of the aforementioned non-aqueous secondary batteries to the minimum capacity (A) is 1.05 < B / A < 2.00.

[0033] [5] The battery pack according to any one of [1] to [4] above, wherein the aforementioned non-aqueous solvent comprises acetonitrile and chain carbonate.

[0034] [6] According to the battery pack described above [5], the volume ratio of acetonitrile in the aforementioned non-aqueous solvent is less than the volume ratio of the chain carbonate.

[0035] [7] The battery pack according to any one of [1] to [6] above, wherein the electrolyte salt comprises an imide salt and LiPF6, the content of the imide salt is more than 0.5 mol and less than 3 mol relative to 1 L of the non-aqueous solvent, and the molar ratio in the non-aqueous electrolyte is LiPF6 < imide salt.

[0036] [8] The battery pack according to any one of [1] to [7] above, wherein the ionic conductivity of the aforementioned non-aqueous electrolyte at 25°C is 10 to 50 mS / cm.

[0037] [9] The battery pack according to any one of [1] to [8] above, wherein the unit area weight of the positive electrode active material layer contained in the aforementioned positive electrode is 15 to 100 mg / cm². 2 .

[0038]

[10] The battery pack according to any one of [1] to [9] above, wherein the aforementioned positive electrode contains a lithium-containing compound containing Fe.

[0039]

[11] The battery pack according to any one of [1] to

[10] above, wherein the aforementioned negative electrode contains graphite or at least one element selected from the group consisting of Ti, V, Sn, Cr, Mn, Fe, Co, Ni, Zn, Al, Si and B.

[0040]

[12] A non-aqueous electrolyte comprising: a redox shuttle and a non-aqueous electrolyte containing an electrolyte salt and a non-aqueous solvent.

[0041] The non-aqueous solvent contains acetonitrile and chain carbonates in an amount of 5 to 95% by volume relative to the total amount.

[0042] The redox shuttle comprises a compound represented by the following general formula (1).

[0043]

[0044] {In equation (1), R} 1 R 2 R 3 R 4 R 5 and R 6 The substituents shown are independently hydrogen atoms, halogen atoms, aryl groups, alkyl groups having 1 to 4 carbon atoms, fluoro-substituted alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms, wherein two or more of these substituents are alkoxy groups having 1 to 4 carbon atoms or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms.

[0045] The compound represented by the aforementioned general formula (1) is contained in 0.1 to 20% by mass relative to the total amount of the non-aqueous electrolyte.

[0046] The electrolyte salt contains an imide salt and LiPF6, wherein the content of the imide salt is more than 0.5 mol and less than 3 mol per 1 L of the non-aqueous solvent, and the molar ratio in the non-aqueous electrolyte is LiPF6 < imide salt.

[0047]

[13] The non-aqueous electrolyte described in

[12] above has an ionic conductivity of 10 to 50 mS / cm at 25°C.

[0048]

[14] According to the non-aqueous electrolyte described in

[12] or

[13] above, wherein the volume ratio of acetonitrile in the aforementioned non-aqueous solvent is less than the volume ratio of the chain carbonate.

[0049]

[15] A method for manufacturing a battery pack, characterized in that it is a method for manufacturing a battery pack having a non-aqueous secondary battery, wherein the non-aqueous secondary battery comprises: a positive electrode, a negative electrode, and a non-aqueous electrolyte containing an electrolyte salt and a non-aqueous solvent, and the manufacturing method includes the following steps:

[0050] The laminate formation process forms a laminate comprising the aforementioned positive electrode and the aforementioned negative electrode;

[0051] The aforementioned manufacturing process of the non-aqueous secondary battery involves housing and sealing the aforementioned laminate and the aforementioned non-aqueous electrolyte within a battery casing; and

[0052] The battery pack is constructed by connecting one or more modules consisting of two or more non-aqueous secondary batteries connected in series in parallel, or by connecting two or more modules consisting of two or more non-aqueous secondary batteries connected in parallel in series.

[0053] The ratio of the maximum capacity (B) to the minimum capacity (A) of each non-aqueous secondary battery constituting the aforementioned module is 1.00 < B / A < 2.00, and the aforementioned non-aqueous electrolyte contains a redox shuttle that has a reversible redox potential at a potential higher than the positive electrode potential when fully charged.

[0054]

[16] In the method of manufacturing the battery pack described above

[15] , the capacity of each of the aforementioned non-aqueous secondary batteries constituting the aforementioned module is 1 mAh or more and 100 Ah or less, and the ratio of the maximum capacity (B) of each of the aforementioned non-aqueous secondary batteries to the minimum capacity (A) is 1.05 < B / A < 2.00.

[0055]

[17] The method for manufacturing the battery pack according to the aforementioned

[15] or

[16] further includes a charging step, which performs an initial charge on the aforementioned non-aqueous secondary battery at a charge of 0.001 to 0.3C.

[0056]

[18] In the method for manufacturing the battery pack according to

[15] or

[16] above, the aforementioned non-aqueous solvent comprises acetonitrile and chain carbonate in an amount of 5 to 95% by volume relative to the total amount.

[0057] The redox shuttle comprises a compound represented by the following general formula (1).

[0058]

[0059] {In equation (1), R} 1 R 2 R 3 R 4 R 5 and R 6 The substituents shown are independently hydrogen atoms, halogen atoms, aryl groups, alkyl groups having 1 to 4 carbon atoms, fluoro-substituted alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms, wherein two or more of these substituents are alkoxy groups having 1 to 4 carbon atoms or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms.

[0060] The compound represented by the aforementioned general formula (1) is contained in 0.1 to 20% by mass relative to the total amount of the non-aqueous electrolyte.

[0061] The electrolyte salt contains an imide salt and LiPF6, wherein the content of the imide salt is more than 0.5 mol and less than 3 mol per 1 L of the non-aqueous solvent, and the molar ratio in the non-aqueous electrolyte is LiPF6 < imide salt.

[0062] The effects of the invention

[0063] According to the present invention, a high-capacity battery pack can be provided that eliminates the balance deviation between two or more non-aqueous secondary batteries when charging at high current density, even if the initial capacity of each non-aqueous secondary battery constituting the battery pack is inconsistent, and the charge-discharge cycle is stable. In addition, a non-aqueous electrolyte and battery pack can be provided that eliminate the balance capacity deviation between two or more non-aqueous secondary batteries even at low and high temperatures. Attached Figure Description

[0064] Figure 1 A top view is provided to briefly illustrate an example of a non-aqueous secondary battery according to this embodiment.

[0065] Figure 2 for Figure 1 A sectional view along line AA.

[0066] Figure 3 A circuit diagram is provided to briefly illustrate an example of the battery pack of this embodiment.

[0067] Figure 4 A graph showing the charge-discharge evaluation results of Example 4.

[0068] Figure 5 A graph showing the charge-discharge evaluation results of Comparative Example 4.

[0069] Figure 6 A graph showing the charge-discharge evaluation results of Example 6.

[0070] Figure 7 A graph showing the charge-discharge evaluation results of Example 7.

[0071] Figure 8 A graph showing the charge-discharge evaluation results of Example 8.

[0072] Figure 9 A graph showing the charge-discharge evaluation results of Example 9. Detailed Implementation

[0073] The following provides a detailed description of the methods used to implement the present invention (hereinafter referred to as "this embodiment").

[0074] One embodiment of the present invention is a battery pack, characterized in that it comprises a non-aqueous secondary battery, the non-aqueous secondary battery comprising: a positive electrode, a negative electrode, and a non-aqueous electrolyte containing an electrolyte salt and a non-aqueous solvent.

[0075] The battery pack is constructed by connecting one or more modules consisting of two or more non-aqueous secondary batteries connected in series in parallel, or by connecting two or more modules consisting of two or more non-aqueous secondary batteries connected in parallel in series in series.

[0076] The ratio of the maximum capacity (B) to the minimum capacity (A) of each non-aqueous secondary battery constituting the module is 1.00 < B / A < 2.00, and

[0077] This non-aqueous electrolyte contains a redox shuttle that has a reversible redox potential at a potential higher than the positive electrode potential when fully charged.

[0078] Another embodiment of the present invention is a non-aqueous electrolyte, comprising: a redox shuttle and a non-aqueous electrolyte containing an electrolyte salt and a non-aqueous solvent.

[0079] The non-aqueous solvent contains acetonitrile and chain carbonate in an amount of 5 to 95% by volume relative to the total amount.

[0080] The redox shuttle comprises a compound represented by the following general formula (1).

[0081]

[0082] {In equation (1), R} 1 R 2 R 3 R 4 R 5 and R 6 The substituents shown are independently hydrogen atoms, halogen atoms, aryl groups, alkyl groups having 1 to 4 carbon atoms, fluoro-substituted alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms, wherein two or more of these substituents are alkoxy groups having 1 to 4 carbon atoms or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms.

[0083] The compound represented by the aforementioned general formula (1) is contained in 0.1 to 20% by mass relative to the total amount of the non-aqueous electrolyte.

[0084] The electrolyte salt contains an imide salt and LiPF6, wherein the content of the imide salt is more than 0.5 mol and less than 3 mol per 1 L of the non-aqueous solvent, and the molar ratio in the non-aqueous electrolyte is LiPF6 < imide salt.

[0085] It should be noted that the range of values ​​recorded using "~" in this specification includes the values ​​recorded before and after it.

[0086] The non-aqueous electrolyte or battery pack of this embodiment can provide a non-aqueous electrolyte and a high-capacity battery pack that can eliminate balance deviations between non-aqueous secondary batteries during high current density charging, even if the initial capacities of the individual non-aqueous secondary batteries constituting the battery pack are inconsistent. Furthermore, it can eliminate capacity deviations in balance between non-aqueous secondary batteries even at low and high temperatures.

[0087] Furthermore, when using a non-aqueous electrolyte solvent with high ionic conductivity, the precipitation of poorly soluble redox shuttles can be prevented. This suppresses overcharge degradation even without BMS control, and improves the yield of non-aqueous secondary batteries. In this embodiment, "non-aqueous electrolyte" refers to a non-aqueous electrolyte containing less than 1% by mass of water relative to the total amount of the non-aqueous electrolyte, and containing an electrolyte salt, a non-aqueous solvent, and a redox shuttle with a reversible redox potential. The non-aqueous electrolyte in this embodiment is preferably as water-free as possible, but may contain trace amounts of water if it is within the range that does not hinder the resolution of the problem of the present invention. Such a water content is less than 300 ppm by mass relative to the total amount of the non-aqueous electrolyte, and more preferably less than 200 ppm by mass. With the above-described structure, materials used in conventional non-aqueous electrolytes for lithium-ion batteries can be applied to the non-aqueous electrolyte.

[0088] The non-aqueous secondary battery of this embodiment is a secondary battery that has a positive electrode and a negative electrode, as well as the aforementioned non-aqueous electrolyte. For example, it can be a lithium-ion battery, and more specifically, it can be... Figure 2 The image shows a simplified cross-sectional view of a lithium-ion battery. Figure 1 , 2 The lithium-ion battery 100 shown includes: a separator 170; a positive electrode 150 and a negative electrode 160 clamping the separator 170 from both sides; a positive current collector 130 (connected to the positive electrode 150) and a negative current collector 140 (connected to the negative electrode 160) of a laminated body further clamping the separator 170, the positive electrode 150, and the negative electrode 160; and a battery casing 110 housing them. The laminated body formed by the positive electrode 150, the separator 170, and the negative electrode 160 is immersed in a non-aqueous electrolyte of this embodiment.

[0089] <1. Non-aqueous electrolyte>

[0090] In this embodiment, "non-aqueous electrolyte" refers to an electrolyte in which water accounts for 1% or less of the total amount of the non-aqueous electrolyte. The non-aqueous electrolyte in this embodiment preferably contains as little water as possible; however, it may contain extremely small amounts of water if it is within a range that does not hinder the resolution of the problem of the present invention. Such a water content, in terms of the total amount of the non-aqueous electrolyte, is 300 ppm or less by mass, preferably 200 ppm or less by mass. For the non-aqueous electrolyte, if it has the structure required to achieve the resolution of the problem of the present invention, other constituent elements can be appropriately selected from known non-aqueous electrolytes used in lithium-ion batteries.

[0091] <1-1. Redox Shuttle>

[0092] As a redox shuttle, there are no particular restrictions as long as the compound has a reversible redox potential and the value of that redox potential is near the desired overcharge potential. Here, "having a reversible redox potential" means that irreversible reactions such as decomposition and polymerization of the compound do not easily occur in the electrode, and that the compound can repeatedly undergo interconversion reactions between its oxidized and reduced forms. In this specification, the term "reversible redox potential" is determined by cyclic voltammetry (CV).

[0093] Furthermore, the "to be set overcharge potential" varies depending on the type of positive electrode active material and can be specified by each battery manufacturer within a range that will not cause irreversible reactions such as decomposition of non-aqueous electrolytes. For example, in lithium-ion batteries using LiCoO2 as the positive electrode and graphite as the negative electrode, it is typically set to around 4.2 to 4.4V; in lithium-ion batteries using Li2Mn2O4 as the positive electrode and graphite as the negative electrode, it is typically set to around 4.0 to 4.2V; and in lithium-ion batteries using LiFePO4 as the positive electrode and graphite as the negative electrode, it is typically set to around 3.6 to 3.8V. Additionally, "near" is preferably ±0.05V of the to be set overcharge potential.

[0094] The molecular weight of the redox shuttle is preferably 100 to 500 from the viewpoint of its diffusivity in non-aqueous electrolytes, more preferably 120 to 450, and particularly preferably 140 to 400.

[0095] As a redox shuttle, specifically, for example, a compound represented by the following general formula (1) can be used.

[0096]

[0097] In this general formula (1), R 1 R 2 R 3 R 4 R 5 and R 6 (hereinafter referred to as "R") 1 ~R 6 The substituents shown in the figure are, independently, hydrogen atoms, halogen atoms, aryl groups, alkyl groups having 1 to 4 carbon atoms, fluoro-substituted alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms, wherein two or more of these substituents are alkoxy groups having 1 to 4 carbon atoms or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms.

[0098] Halogen atoms can be fluorine, chlorine, bromine, or iodine. Examples of aryl groups include phenyl. Alkyl groups having 1 to 4 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl. Fluorinated alkyl groups having 1 to 4 carbon atoms include trifluoromethyl. Alkoxy groups having 1 to 4 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, and tert-butoxy. Fluorinated alkoxy groups having 1 to 4 carbon atoms include monofluoromethoxy, difluoromethoxy, 2,2,2-trifluoroethoxy, and 2,2,3,3-tetrafluoropropoxy. Substituents can be any combination of these substituents.

[0099] In the compounds represented by the above general formula (1), R 1 ~R 6 Compounds in which two of the substituents are tert-butyl or trifluoromethyl and the other two are alkoxy groups having 1 to 4 carbon atoms or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms exhibit excellent long-term stability because the π electrons are protected by the steric effect of the tert-butyl or trifluoromethyl group, and the oxygen atoms of the alkoxy or fluoro-substituted alkoxy groups have non-shared electron pairs. Specific examples of such compounds are shown below.

[0100]

[0101] The compounds in the above specific examples can be manufactured by conventional methods, for example, by any of the three reaction routes shown in the following general formulas (2), (3) and (4).

[0102] [Reaction Route 1]

[0103]

[0104] [Reaction Route 2]

[0105]

[0106] [Reaction Route 3]

[0107]

[0108] It should be noted that in general formulas (2), (3) and (4), there are multiple R in one compound. 7 Each of the Rs independently represents an alkyl group having 1 to 4 carbon atoms or a fluoro-substituted alkyl group having 1 to 4 carbon atoms, and multiple Rs exist in a single compound. 8Each can be represented independently as tert-butyl or trifluoromethyl. Examples of alkyl groups having 1 to 4 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl. Examples of fluorosubstituted alkyl groups having 1 to 4 carbon atoms include monofluoromethyl, difluoromethyl, 2,2,2-trifluoroethyl, and 2,2,3,3-tetrafluoropropyl.

[0109] First, the manufacturing method of reaction route 1 shown in the above general formula (2) will be explained.

[0110] In reaction route 1, 2,5-bis(tert-butyl)hydroquinone or 2,5-bistrifluoromethylhydroquinone is mixed with N,N-dimethylformamide, and then NaH is added to the mixture, followed by the addition of iodide R. 7 I. After separating the reaction solution with an organic solvent such as dichloromethane and brine, wash with water to recover the organic solvent, and add a dehydrating agent to dry it. There are no particular limitations on the dehydrating agent, but anhydrous sodium sulfate or anhydrous magnesium sulfate are preferred. After removing the solvent, purify the crude product by silica gel column chromatography to obtain the target compound. There are no particular limitations on the developing solvent for silica gel column chromatography; for example, a developing solvent of chloroform:n-hexane = 1:4 (volume ratio) can be used.

[0111] Next, the manufacturing method of reaction route 2 shown in the above general formula (3) will be described.

[0112] In reaction route 2, 2,5-bis(tert-butyl)hydroquinone or 2,5-bistrifluoromethylhydroquinone, potassium carbonate, tri-n-butylamine, and acetone are mixed under a nitrogen atmosphere, and then perfluorobutyl sulfonate C4F9SO3R is added dropwise to the mixture. 7 For example, 2,2,2-trifluoroethyl perfluorobutyl sulfonate. There are no particular limitations on the reaction temperature at this stage, but 40–70°C is preferred, more preferably 50–65°C, and even more preferably 57–63°C. Water is then added to stop the reaction, and acetone is removed by concentration under reduced pressure. After cooling, the mixture is filtered and dried, and the residue is purified by silica gel column chromatography to obtain the target compound. There are no particular limitations on the developing solvent for silica gel column chromatography; examples include developing solvents such as chloroform:n-hexane = 1:10 (volume ratio).

[0113] Next, the manufacturing method of reaction route 3 shown in the above general formula (4) will be described.

[0114] In reaction route 3, methanol and periodic acid are mixed, iodine is added, and the mixture is stirred. Then, 1,4-dialkoxybenzene or 1,4-di(fluorosubstituted alkoxy)benzene is added and stirred. The reaction temperature is not particularly limited at this stage, but is preferably 50–80°C, more preferably 60–75°C, and even more preferably 67–73°C. After the reaction is complete, the resulting solution is injected into a mixture of Na₂S₂O₅ and water. The precipitate is filtered, dried, and the resulting powder is purified by silica gel column chromatography to obtain 2,5-diiodide as an intermediate product. The developing solvent for silica gel column chromatography is not particularly limited; dichloromethane is an example.

[0115] Then, the above intermediate product, sodium trifluoroacetate, copper iodide, and N,N-dimethylacetamide are mixed and refluxed under a nitrogen atmosphere. The reflux temperature is not particularly limited, but preferably 130–160°C, more preferably 140–155°C, and even more preferably 147–153°C. The resulting solution is cooled, filtered, and separated with an organic solvent such as dichloromethane and water. After washing with water, the organic solvent is recovered, and a dehydrating agent is added to dry the solution. The dehydrating agent is not particularly limited, but preferably anhydrous sodium sulfate or anhydrous magnesium sulfate. After solvent removal, the crude product is purified by silica gel column chromatography to obtain the target compound. The developing solvent for silica gel column chromatography is not particularly limited; examples include dichloromethane.

[0116] Regarding the content of the redox shuttle in the non-aqueous electrolyte of this embodiment, it is preferably 0.1 to 20% by mass relative to the total amount of the non-aqueous electrolyte, more preferably 0.5 to 10% by mass. If the content is 0.1% by mass or more, the overcharge prevention effect caused by the cycling effect of the redox reaction is obtained more effectively. If the content is 20% by mass or less, the decrease in ionic conductivity is small, further reducing the impact on battery characteristics such as input / output characteristics and battery life.

[0117] <1-2. Non-aqueous solvents>

[0118] In this embodiment, "non-aqueous solvent" refers to an element from which electrolyte salts, including lithium salts, and various additives have been removed from the non-aqueous electrolyte. When the non-aqueous electrolyte contains electrode protection additives, "non-aqueous solvent" refers to an element from which lithium salts and additives other than electrode protection additives have been removed from the non-aqueous electrolyte. Examples of non-aqueous solvents include alcohols such as methanol and ethanol; and aprotic solvents. Among these, aprotic solvents are preferred as non-aqueous solvents. However, the non-aqueous solvent may also contain solvents other than aprotic solvents, as long as it does not impede the resolution of the problem of the present invention.

[0119] For example, the non-aqueous solvent of a non-aqueous electrolyte can contain acetonitrile as an aprotic solvent. By including acetonitrile in the non-aqueous solvent, the ionic conductivity of the non-aqueous electrolyte is improved, thereby enhancing the diffusion of lithium ions within the battery. Therefore, when the non-aqueous electrolyte contains acetonitrile, especially in positive electrodes with thickened positive electrode active material layers and increased positive electrode active material loading, lithium ions can diffuse well to regions near the current collector that are difficult for lithium ions to reach under high-load discharge. Thus, sufficient capacity can be obtained even under high-load discharge, resulting in a non-aqueous secondary battery with excellent load characteristics.

[0120] Furthermore, by including acetonitrile in the non-aqueous solvent, the fast-charging characteristics of non-aqueous secondary batteries can be improved. In constant-current (CC)-constant-voltage (CV) charging of non-aqueous secondary batteries, the capacity per unit time during CC charging is greater than the capacity per unit time during CV charging. Using acetonitrile as a non-aqueous solvent in the non-aqueous electrolyte expands the CC-chargeable region (extends the CC charging time) and also increases the charging current, thus significantly shortening the time required for the non-aqueous secondary battery to reach a fully charged state from the start of charging.

[0121] It should be noted that acetonitrile is readily reduced and decomposed electrochemically. Therefore, when using acetonitrile as a non-aqueous solvent, it is preferable to use it in combination with other solvents (e.g., non-protic solvents other than acetonitrile) and / or add electrode protection additives for forming a protective coating on the electrode.

[0122] The acetonitrile content, relative to the total amount of non-aqueous solvent, is preferably 5 to 95% by volume. More preferably, it is 10% by volume or more, and even more preferably 20% by volume or more. This value is more preferably 85% by volume or less, and even more preferably 66% by volume or less. When the acetonitrile content is 5% by volume or more relative to the total amount of non-aqueous solvent, there is a tendency for increased ionic conductivity and high output characteristics, which in turn promotes lithium salt dissolution. Since the additives described later suppress the increase in battery internal resistance, when the acetonitrile content in the non-aqueous solvent is within the above range, there is a tendency to maintain the excellent performance of acetonitrile and further improve high-temperature cycling characteristics and other battery characteristics.

[0123] Examples of aprotic solvents other than acetonitrile include cyclic carbonates, fluoroethylene carbonates, lactones, organic compounds containing sulfur atoms, chain carbonates, chain fluorinated carbonates, cyclic ethers, mononitriles other than acetonitrile, alkoxy-substituted nitriles, dinitriles, cyclic nitriles, short-chain fatty acid esters, chain ethers, fluorinated ethers, ketones, and compounds in which some or all of the H atoms of the aforementioned aprotic solvents are replaced by halogen atoms.

[0124] Examples of cyclic carbonates include ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, trans-butylene carbonate, cis-butylene carbonate, 1,2-pentene carbonate, trans-pentene carbonate, cis-pentene carbonate, vinylene carbonate, 4,5-dimethylethyleneene carbonate, and vinyl ethylene carbonate.

[0125] Examples of fluoroethylene carbonates include 4-fluoro-1,3-dioxolane-2-one, 4,4-difluoro-1,3-dioxolane-2-one, cis-4,5-difluoro-1,3-dioxolane-2-one, trans-4,5-difluoro-1,3-dioxolane-2-one, 4,4,5-trifluoro-1,3-dioxolane-2-one, 4,4,5,5-tetrafluoro-1,3-dioxolane-2-one, and 4,4,5-trifluoro-5-methyl-1,3-dioxolane-2-one.

[0126] Examples of lactones include γ-butyrolactone, α-methyl-γ-butyrolactone, γ-valerolactone, γ-caprolactone, δ-valerolactone, δ-caprolactone, and ε-caprolactone.

[0127] Examples of organic compounds containing sulfur atoms include ethylene sulfite, propylene sulfite, butyl sulfite, pentene sulfite, sulfolane sulfonate, sulfolane sulfonate, 3-cyclobutene sulfonate, 3-methyl sulfolane sulfonate, 1,3-propane sulpholactone, 1,4-butane sulpholactone, 1-propene 1,3-sulpholactone, dimethyl sulfoxide, tetramethylene sulfoxide, and ethylene glycol sulfite.

[0128] Examples of chain carbonates include ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, methyl butyl carbonate, dibutyl carbonate, ethyl propyl carbonate, and diisobutyl carbonate.

[0129] Examples of cyclic ethers include tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, and 1,3-dioxane;

[0130] Examples of mononitrile other than acetonitrile include propionitrile, butyronitrile, valerate, benzonitrile, and acrylonitrile;

[0131] Examples of alkoxy-substituted nitriles include methoxyacetonitrile and 3-methoxypropionitrile;

[0132] Examples of dinitrile include malononitrile, succinate, glutaronitrile, adiponitrile, 1,4-dicyanoheptane, 1,5-dicyanopentane, 1,6-dicyanhexane, 1,7-dicyanoheptane, 2,6-dicyanoheptane, 1,8-dicyanoctane, 2,7-dicyanoctane, 1,9-dicyanonane, 2,8-dicyanonane, 1,10-dicyandecane, 1,6-dicyandecane, and 2,4-dimethylglutaronitrile;

[0133] Examples of cyclic nitrile include benzonitrile;

[0134] Examples of short-chain fatty acid esters include methyl acetate, methyl propionate, methyl isobutyrate, methyl butyrate, methyl isovalerate, methyl valerate, methyl neovalerate, methyl angelic acid ester, methyl hexanoate, ethyl acetate, ethyl propionate, ethyl isobutyrate, ethyl butyrate, ethyl isovalerate, ethyl valerate, ethyl neovalerate, ethyl angelic acid ester, ethyl hexanoate, propyl acetate, propyl propionate, propyl isobutyrate, propyl isovalerate, propyl valerate, propyl neovalerate, propyl angelic acid ester, propyl hexanoate, isopropyl acetate, isopropyl propionate, isopropyl isobutyrate, isopropyl butyrate, isopropyl isovalerate, and so on. Isopropyl valerate, isopropyl neovalerate, isopropyl hydrogenated angelica, isopropyl hexanoate, butyl acetate, butyl propionate, butyl isobutyrate, butyl butyrate, butyl isovalerate, butyl valerate, butyl neovalerate, butyl hydrogenated angelica, butyl hexanoate, isobutyl acetate, isobutyl propionate, isobutyl isobutyrate, isobutyl butyrate, isobutyl isovalerate, isobutyl valerate, isobutyl neovalerate, isobutyl hydrogenated angelica, isobutyl hexanoate, tert-butyl acetate, tert-butyl propionate, tert-butyl isobutyrate, tert-butyl butyrate, tert-butyl isovalerate, tert-butyl valerate, tert-butyl neovalerate, tert-butyl hydrogenated angelica, and tert-butyl hexanoate;

[0135] Examples of chain ethers include dimethoxyethane, diethyl ether, 1,3-dioxolane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether.

[0136] Examples of fluorinated ethers include Rf. 20 -OR 21 (Rf 20 alkyl groups containing fluorine atoms, R 7 (These can be organic groups that contain fluorine atoms);

[0137] Examples of ketones include acetone, methyl ethyl ketone, and methyl isobutyl ketone.

[0138] Compounds in which some or all of the H atoms of the aforementioned aprotic solvent are replaced by halogen atoms include compounds in which the halogen atom is fluorine.

[0139] Examples of fluorinated chain carbonates include, for instance, methyl trifluoroethyl carbonate, trifluorodimethyl carbonate, trifluorodiethyl carbonate, trifluoroethyl methyl carbonate, methyl 2,2-difluoroethyl carbonate, methyl 2,2,2-trifluoroethyl carbonate, and methyl 2,2,3,3-tetrafluoropropyl carbonate. These fluorinated chain carbonates can be represented by the following general formula:

[0140] R 7 -OC(O)OR 8

[0141] In the formula, R 7 and R 8 The free radicals CH3, CH2CH3, CH2CH2CH3, CH(CH3)2, and CH2Rf are selected. 9 At least one of the groups, Rf 9 It is an alkyl group having 1 to 3 carbon atoms formed by replacing at least one hydrogen atom with a fluorine atom, and R 7 and / or R 8 It contains at least one fluorine atom.

[0142] In addition, examples of fluorinated short-chain fatty acid esters include fluorinated short-chain fatty acid esters such as 2,2-difluoroethyl acetate, 2,2,2-trifluoroethyl acetate, and 2,2,3,3-tetrafluoropropyl acetate. Fluorinated short-chain fatty acid esters can be represented by the following general formula:

[0143] R 10 -C(O)OR 11

[0144] In the formula, R 10 The free radicals are CH3, CH2CH3, CH2CH2CH3, CH(CH3)2, CF3CF2H, CFH2, and CF2Rf. 12 CFHRf 12 and CH2Rf 13 At least one of the groups, R 11 The free radicals CH3, CH2CH3, CH2CH2CH3, CH(CH3)2, and CH2Rf are selected. 13 At least one of the groups, Rf 12 Rf is an alkyl group having 1 to 3 carbon atoms in which at least one hydrogen atom is replaced by at least one fluorine atom. 13 It is an alkyl group having 1 to 3 carbon atoms formed by replacing at least one hydrogen atom with a fluorine atom, and R 10 and / or R 11 Contains at least one fluorine atom, R 10 In the case of CF2H, R 11 Not CH3.

[0145] In this embodiment, the aprotic solvent other than acetonitrile can be used alone or in combination of two or more. The aprotic solvent other than acetonitrile is preferably 5 to 95% by volume relative to the total amount of the non-aqueous solvent. More preferably, it is 15% by volume or more, and even more preferably 34% by volume or more, relative to the total amount of the non-aqueous solvent. This value is more preferably 90% by volume or less, and even more preferably 80% by volume or less. When the acetonitrile content is 5% by volume or more relative to the total amount of the non-aqueous solvent, there is a tendency for increased ionic conductivity, resulting in higher output characteristics, which in turn promotes lithium salt dissolution. When the acetonitrile content is 95% by volume or less relative to the total amount of the non-aqueous solvent, there is a tendency to maintain the excellent performance of acetonitrile and to improve high-temperature cycling characteristics and other battery characteristics.

[0146] It should be noted that the proportions of acetonitrile and other aprotic solvents in non-aqueous solvents can be determined by gas chromatography-mass spectrometry (GC / MS).

[0147] From the viewpoint of improving the stability of non-aqueous electrolytes, in this embodiment, the non-aqueous solvent is preferably used in combination with acetonitrile, and preferably with one or more of cyclic carbonates and linear carbonates. From this viewpoint, the non-aqueous solvent in this embodiment is more preferably used in combination with cyclic carbonates while using acetonitrile, and even more preferably used in combination with both cyclic carbonates and linear carbonates while using acetonitrile.

[0148] When using acetonitrile in conjunction with cyclic carbonates, the cyclic carbonates particularly preferably contain ethylene carbonate, vinylene carbonate, and / or fluoroethylene carbonate.

[0149] When acetonitrile and chain carbonate are included as the aforementioned non-aqueous solvent, the precipitation of the poorly soluble redox shuttle can be prevented, which is therefore preferred. Furthermore, when the volume ratio of acetonitrile in the aforementioned non-aqueous solvent is less than the volume ratio of chain carbonate, the redox shuttle function is effectively performed even at low temperatures, which is also preferred.

[0150] <1-3. Electrolyte Salts>

[0151] Regarding the lithium salt in the non-aqueous electrolyte of this embodiment, there are no particular limitations unless otherwise specified above. For example, in this embodiment, LiPF6 or an imide salt is included as the lithium salt.

[0152] Imide salts refer to LiN(SO2C) m F 2m+1The lithium salt shown in )2 [m is an integer from 0 to 8] preferably includes at least one of LiN(SO2F)2 and LiN(SO2CF3)2. It may contain only one of these imide salts, or two. Alternatively, it may contain imide salts other than these imide salts.

[0153] When the non-aqueous solvent contains acetonitrile, the saturation concentration of the imide salt in acetonitrile is higher than that of LiPF6 in acetonitrile. Therefore, when the imide salt is contained at a molar concentration where LiPF6 ≤ imide salt, the association and precipitation of lithium salt with acetonitrile at low temperatures can be suppressed, which is preferred. Furthermore, containing the imide salt at a molar concentration where LiPF6 < imide salt yields a more significant effect, which is even more preferred. Moreover, from the viewpoint of ion supply, the imide salt content relative to 1L of the non-aqueous solvent is preferably 0.5 mol or more and 3 mol or less, more preferably 1 mol or more and 2 mol or less. Using an acetonitrile-containing non-aqueous electrolyte containing at least one of LiN(SO2F)2 and LiN(SO2CF3)2 can suppress the decrease in ionic conductivity in low-temperature regions such as -10°C or -30°C, resulting in excellent low-temperature characteristics. By limiting the content in this way, the increase in resistance during high-temperature heating can also be suppressed more effectively.

[0154] In addition, lithium salts can include fluorine-containing inorganic lithium salts other than LiPF6, such as LiBF4, LiAsF6, Li2SiF6, LiSbF6, and Li2B. 12 F b H 12-b Fluorine-containing inorganic lithium salts, where b is an integer from 0 to 3. "Inorganic lithium salt" refers to lithium salts whose anions do not contain carbon atoms and are soluble in acetonitrile. "Fluorine-containing inorganic lithium salt" refers to lithium salts whose anions do not contain carbon atoms, contain fluorine atoms, and are soluble in acetonitrile. From the viewpoint of forming a passivation coating on the surface of the metal foil used as the positive electrode current collector and inhibiting corrosion of the positive electrode current collector, fluorine-containing inorganic lithium salts are superior. These fluorine-containing inorganic lithium salts can be used alone or in combination of two or more. Ideally, fluorine-containing inorganic lithium salts are complex salts of LiF and Lewis acids; among them, fluorine-containing inorganic lithium salts containing phosphorus atoms are more preferred as they readily release free fluorine atoms. A representative fluorine-containing inorganic lithium salt is LiPF6, which dissolves and releases PF6 anions. When using a fluorinated inorganic lithium salt containing boron atoms as the fluorinated inorganic lithium salt, LiBF4 is preferred because it is easy to capture excess free acid components that may lead to battery degradation. From this point of view, LiBF4 is particularly preferred.

[0155] The content of fluorinated inorganic lithium salt in the non-aqueous electrolyte of this embodiment is not particularly limited, but is preferably 0.01 mol or more, more preferably 0.02 mol or more, and even more preferably 0.03 mol or more, relative to 1 L of non-aqueous solvent. When the content of fluorinated inorganic lithium salt is within the above range, there is a tendency for increased ionic conductivity and high output characteristics. In addition, it is preferably less than 1.5 mol, more preferably less than 0.5 mol, and even more preferably less than 0.1 mol, relative to 1 L of non-aqueous solvent. When the content of fluorinated inorganic lithium salt is within the above range, the ionic conductivity increases and high output characteristics are exhibited, and there is a tendency to suppress the decrease in ionic conductivity associated with increased viscosity at low temperatures, maintain the excellent performance of the non-aqueous electrolyte, and further improve high-temperature cycling characteristics and other battery characteristics.

[0156] The non-aqueous electrolyte of this embodiment may further include an organolithium salt. "Organolithium salt" refers to a lithium salt whose anion contains a carbon atom and is soluble in acetonitrile. Examples of organolithium salts include those with oxalate groups. Specific examples of organolithium salts with oxalate groups include, for example, organolithium salts represented by LiB(C2O4)2, LiBF2(C2O4), LiPF4(C2O4), and LiPF2(C2O4)2, etc., wherein at least one lithium salt selected from the lithium salts represented by LiB(C2O4)2 and LiBF2(C2O4) is preferred. Furthermore, it is more preferable to use one or more of these lithium salts together with a fluorine-containing inorganic lithium salt. This organolithium salt with oxalate groups can be added not only to the non-aqueous electrolyte but also contained in the negative electrode (negative electrode active material layer).

[0157] Regarding the amount of organolithium salt with oxalate groups added to the non-aqueous electrolyte, from the viewpoint of better ensuring the effect achieved through its use, it is preferably 0.005 mol or more, more preferably 0.02 mol or more, and even more preferably 0.05 mol or more, relative to 1 L of the non-aqueous solvent in the non-aqueous electrolyte. However, if the aforementioned organolithium salt with oxalate groups is added in excessive amounts to the non-aqueous electrolyte, precipitation may occur. Therefore, the amount of the aforementioned organolithium salt with oxalate groups added to the non-aqueous electrolyte, relative to 1 L of the non-aqueous solvent in the non-aqueous electrolyte, is preferably less than 1.0 mol, more preferably less than 0.5 mol, and even more preferably less than 0.2 mol.

[0158] It is known that organolithium salts containing oxalate groups are poorly soluble in low-polarity organic solvents, especially chain carbonates. Sometimes, organolithium salts containing oxalate groups contain trace amounts of lithium oxalate. When mixed with other raw materials to form a non-aqueous electrolyte, they may react with trace amounts of moisture in other raw materials to form a new white precipitate of lithium oxalate. Therefore, the lithium oxalate content in the non-aqueous electrolyte of this embodiment is not particularly limited, but is preferably 0 to 500 ppm.

[0159] In addition to the lithium salts described above, lithium salts commonly used in non-aqueous secondary batteries can also be added as the lithium salts used in this embodiment. Specific examples of other lithium salts include LiClO4, LiAlO4, LiAlCl4, and LiB. 10 Cl 10 Inorganic lithium salts such as lithium chloroborane, which do not contain fluorine atoms in their anions; LiCF3SO3, LiCF3CO2, Li2C2F4(SO3)2, LiC(CF3SO2)3, LiC n F (2n+1) SO3 (n≥2), lower aliphatic carboxylic acids such as lithium, lithium tetraphenylborate, and organic lithium salts such as LiB(C3O4H2)2; and LiPF5 (CF3) and other LiPF6 salts. n (C p F 2p+1 ) 6-n [n is an integer from 1 to 5, p is an integer from 1 to 8] This refers to organolithium salts; LiBF3 (CF3) and other LiBF... q (C s F 2s+1 ) 4-q [q is an integer from 1 to 3, s is an integer from 1 to 8] The organolithium salt shown; lithium salts combined with polyvalent anions; expressed by the following general formula (A):

[0160] LiC(SO2R A (SO2R) B (SO2R) C (A)

[0161] In the formula, R A R B and R C Choose any of the same or different perfluoroalkyl groups, representing 1 to 8 carbon atoms. The following general formula (B):

[0162] LiN(SO2OR D (SO2OR) E (B)

[0163] In the formula, R D and R E Choose any of the same or different ones to represent perfluoroalkyl groups having 1 to 8 carbon atoms.

[0164] The following general formula (C):

[0165] LiN(SO2R F (SO2OR) G (C)

[0166] In the formula, R F and R G The perfluoroalkyl groups, which may be the same or different from each other, represent 1 to 8 carbon atoms. The organolithium salts, etc., which are respectively represented, can be used together with fluorine-containing inorganic lithium salts.

[0167] <1-4. Additives>

[0168] <Additives for Electrode Protection>

[0169] The non-aqueous electrolyte in this embodiment may contain additives for protecting the electrodes. There are no particular limitations on the electrode protection additives, as long as they do not hinder the resolution of the problem of this invention. They may substantially overlap with substances that act as solvents for dissolving lithium salts (i.e., the aforementioned non-aqueous solvents). The electrode protection additives are preferably substances that contribute to improving the performance of the non-aqueous electrolyte and the non-aqueous secondary battery in this embodiment, and also include substances that do not directly participate in the electrochemical reaction.

[0170] Specific examples of additives for electrode protection include: fluoroethylene carbonates represented by 4-fluoro-1,3-dioxolane-2-one, 4,4-difluoro-1,3-dioxolane-2-one, cis-4,5-difluoro-1,3-dioxolane-2-one, trans-4,5-difluoro-1,3-dioxolane-2-one, 4,4,5-trifluoro-1,3-dioxolane-2-one, 4,4,5,5-tetrafluoro-1,3-dioxolane-2-one, and 4,4,5-trifluoro-5-methyl-1,3-dioxolane-2-one; cyclic carbonates containing unsaturated bonds represented by vinylene carbonate, 4,5-dimethyl vinylene carbonate, and vinylene carbonate; and γ-butyrolactone, γ-valerolactone, γ-caprolactone, δ-valerolactone, and δ-valerolactone. Lactones represented by -caprolactone and ε-caprolactone; cyclic ethers represented by 1,4-dioxane; cyclic sulfur compounds represented by ethylene sulfite, propylene sulfite, butyl sulfite, pentene sulfite, sulfolane, 3-cyclobutene sulfone, 3-methylsulfolane, 1,3-propanesulfonyl lactone, 1,4-butanesulfonyl lactone, 1-propene 1,3-sulfonyl lactone, and tetramethylene sulfoxide; chain anhydrides represented by acetic anhydride, propionic anhydride, and benzoic anhydride; cyclic anhydrides represented by malonic anhydride, succinic anhydride, glutaric anhydride, maleic anhydride, phthalic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 2,3-naphthalenedicarboxylic anhydride, or naphthalene-1,4,5,8-tetracarboxylic anhydride; and mixed anhydrides formed by the dehydration condensation of two different carboxylic acids or different types of acids such as carboxylic acids and sulfonic acids. These can be used individually or in combination of two or more.

[0171] There is no particular limitation on the content of the electrode protection additive in the non-aqueous electrolyte of this embodiment. The content of the electrode protection additive relative to the total amount of non-aqueous solvent is preferably 0.1 to 30% by volume, more preferably 0.3 to 15% by volume, and even more preferably 0.5 to 4% by volume.

[0172] In this embodiment, a higher content of electrode protection additives further suppresses the degradation of the non-aqueous electrolyte. However, a lower content of electrode protection additives results in higher output characteristics of the non-aqueous secondary battery at low temperatures. Therefore, by adjusting the content of electrode protection additives to the aforementioned range, it is possible to maximize the superior performance based on the high ionic conductivity of the non-aqueous electrolyte without compromising its fundamental function as a non-aqueous secondary battery. By preparing the non-aqueous electrolyte with this composition, there is a tendency to improve the cycle performance, high output performance at low temperatures, and other battery characteristics of the non-aqueous secondary battery.

[0173] It should be noted that acetonitrile, as one of the components of the non-aqueous solvent, is easily reduced and decomposed electrochemically. Therefore, the non-aqueous solvent containing acetonitrile preferably contains one or more cyclic aprotic polar solvents, and more preferably contains one or more cyclic carbonates with unsaturated bonds as an electrode protection additive for forming a protective coating on the negative electrode.

[0174] As a cyclic carbonate containing unsaturated bonds, vinylene carbonate is preferred. The content of vinylene carbonate in the non-aqueous electrolyte is preferably 0.1% by volume or more and 10% by volume or less, more preferably 0.2% by volume or more and less than 5% by volume, and even more preferably 0.5% by volume or more and less than 3% by volume. This can more effectively improve low-temperature durability and provide a secondary battery with excellent low-temperature performance.

[0175] Ethylene carbonate, as an electrode protection additive, suppresses the reductive decomposition reaction of acetonitrile on the negative electrode surface, and is therefore usually necessary; insufficient addition can lead to a sharp decline in battery performance. On the other hand, excessive coating formation can result in reduced low-temperature performance. Therefore, by adjusting the amount of vinylene carbonate added to the above-mentioned range, the interfacial (coating) resistance can be kept low, and low-temperature cycle degradation can be suppressed.

[0176] <Any other additives>

[0177] In this embodiment, in order to improve the charge-discharge cycle characteristics, high-temperature storage performance, and safety (e.g., to prevent overcharging) of the non-aqueous secondary battery, the non-aqueous electrolyte may contain appropriate additives selected from any of the following substances: sulfonates, diphenyl disulfides, cyclohexylbenzene, biphenyl, fluorobenzene, tert-butylbenzene, phosphate esters [ethyl diethylphosphonoacetate (EDPA): (C2H5O)2(P=O)-CH2(C=O)OC2H5, tri(trifluoroethyl) phosphate (TFEP): (CF3CH2O)3P=O, triphenyl phosphate (TPP): (C6H5O)3P=O: (CH2=CHCH2O)3P=O, triallyl phosphate, etc.], nitrogen-containing cyclic compounds without steric hindrance around non-shared electron pairs [pyridine, 1-methyl-1H-benzotriazole, 1-methylpyrazole, etc.], and derivatives of these compounds. Phosphate esters, in particular, are effective in inhibiting side reactions during storage.

[0178] The content of any other additives in this embodiment is calculated as a percentage by mass relative to the total mass of all components constituting the non-aqueous electrolyte. There are no particular limitations on the content of any other additives, but it is preferably in the range of 0.01% by mass or more and 10% by mass or less relative to the total amount of the non-aqueous electrolyte, more preferably 0.02% by mass or more and 5% by mass or less, and even more preferably 0.05% to 3% by mass. By adjusting the content of any other additives to the above range, there is a tendency to add further good battery characteristics without impairing the basic function of the non-aqueous secondary battery.

[0179] <2. Positive electrode and positive current collector>

[0180] The positive electrode 150 consists of a positive electrode current collector and a layer of positive electrode active material made using a positive electrode agent. The positive electrode 150 is not particularly limited as long as it functions as the positive electrode in a non-aqueous secondary battery, and can be any known positive electrode. From the perspective of excellent long-term durability of the redox shuttle, the positive electrode in this invention preferably contains a lithium-containing compound containing Fe.

[0181] The positive electrode active material layer contains positive electrode active material, and preferably also contains conductive additives and binders as needed.

[0182] The positive electrode active material layer preferably contains a material capable of absorbing and releasing lithium ions. Using such a material tends to result in high voltage and high energy density, and is therefore preferred.

[0183] Examples of positive electrode active materials include those containing at least one transition metal element selected from the group consisting of Ni, Mn, and Co, with at least one Li-containing metal oxide selected from the Li-containing metal oxides shown in general formula (a) below being preferred.

[0184] Li p Ni q Co r Mn s M t O u ···(a)

[0185] {In the formula, M is at least one metal selected from the group consisting of Al, Sn, In, Fe, V, Cu, Mg, Ti, Zn, Mo, Zr, Sr, and Ba, and is within the range of 0 < p < 1.3, 0 < q < 1.2, 0 < r < 1.2, 0 ≤ s < 0.5, 0 ≤ t < 0.3, 0.7 ≤ q + r + s + t ≤ 1.2, and 1.8 < u < 2.2, and p is a value determined by the charge / discharge state of the battery.}

[0186] Specific examples of positive electrode active materials include lithium cobalt oxides represented by LiCoO2; lithium manganese oxides represented by LiMnO2, LiMn2O4, and Li2Mn2O4; lithium nickel oxides represented by LiNiO2; and LiNi... 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.8 Co 0.2 O2 represents Li z The lithium-containing composite metal oxides, etc., are represented by MO2 (M contains at least one transition metal element selected from the group consisting of Ni, Mn and Co, and represents two or more metal elements selected from the group consisting of Ni, Mn, Co, Al and Mg, and z represents a number greater than 0.9 and less than 1.2).

[0187] In particular, when the Ni content ratio q of the Li-containing metal oxide shown in general formula (a) is 0.5 < q < 1.2, it is preferable to achieve both a reduction in the amount of Co used as a rare metal and a high energy density. Examples of such positive electrode active materials include LiNi. 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.75 Co 0.15 Mn 0.15 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.85 Co 0.075 Mn 0.075 O2, LiNi 0.8 Co 0.15 Al 0.05 O2, LiNi 0.81 Co 0.1 Al 0.09 O2, LiNi 0.85 Co 0.1 Al 0.05 Lithium-containing composite metal oxides, such as O2.

[0188] On the other hand, there is a tendency for higher Ni content to lead to more significant degradation at low voltages. The positive electrode active material containing Li metal oxides, as shown in general formula (a), inherently contains active sites that oxidize and degrade non-aqueous electrolytes. These active sites may inadvertently consume compounds added on the positive electrode side to protect the negative electrode. Anhydrides are particularly susceptible to this effect. Especially when acetonitrile is used as a non-aqueous solvent, the effect of adding anhydrides is extremely significant, making the consumption of anhydrides on the positive electrode side a critical issue.

[0189] Furthermore, the decomposition products of these additives introduced and accumulated on the positive electrode side not only become a major cause of increased internal resistance in non-aqueous secondary batteries, but also accelerate the degradation of lithium salts. Consequently, the original purpose of protecting the negative electrode surface becomes insufficient. In order to deactivate the active sites that essentially oxidize and degrade the non-aqueous electrolyte, it is important to have components that act as controls or neutralizers for Young's-Taylor distortion. Therefore, the positive electrode active material preferably contains at least one metal selected from the group consisting of Al, Sn, In, Fe, V, Cu, Mg, Ti, Zn, Mo, Zr, Sr, and Ba.

[0190] For the same reason, it is preferable that the surface of the positive electrode active material is covered with a compound containing at least one metal element selected from the group consisting of Zr, Ti, Al, and Nb. More preferably, the surface of the positive electrode active material is covered with an oxide containing at least one metal element selected from the group consisting of Zr, Ti, Al, and Nb. Furthermore, the method of covering the surface of the positive electrode active material with an oxide selected from the group consisting of ZrO2, TiO2, Al2O3, NbO3, and LiNbO2 is particularly preferred because it does not hinder the permeation of lithium ions.

[0191] As the positive electrode active material, it can be a lithium-containing compound other than the Li-containing metal oxide shown in general formula (a), as long as it contains lithium, there is no particular limitation. Examples of such lithium-containing compounds include, for instance, complex oxides containing lithium and transition metal elements, metal chalcogenides containing lithium, metal phosphate compounds containing lithium and transition metal elements, and metal silicate compounds containing lithium and transition metal elements. From the viewpoint of obtaining higher voltage, metal phosphate compounds containing lithium and at least one transition metal element selected from the group consisting of Co, Ni, Mn, Fe, Cu, Zn, Cr, V, and Ti are particularly preferred as lithium-containing compounds.

[0192] More specifically, examples of lithium-containing compounds include those represented by the following formulas (Xa), (Xb), and (Xc).

[0193] Li v M I D2 (Xa)

[0194] In the formula, D represents the chalcogenide element, M I This indicates one or more transition metal elements containing at least one transition metal element. The value of v is determined by the charge / discharge state of the battery and represents a number from 0.05 to 1.10, while u represents a number from 0 to 2.

[0195] Li w M II PO4 (Xb)

[0196] In the formula, D represents the chalcogenide element, M II The expression represents one or more transition metal elements containing at least one transition metal element, where the value of w is determined by the charge / discharge state of the battery and represents a number from 0.05 to 1.10, and u represents a number from 0 to 2.

[0197] Li t M III u SiO4 (Xc)

[0198] In the formula, D represents the chalcogenide element, M III It represents one or more transition metal elements containing at least one transition metal element, where the value of t is determined by the charge / discharge state of the battery and represents a number from 0.05 to 1.10, and u represents a number from 0 to 2.

[0199] The lithium-containing compound shown in formula (Xa) above has a layered structure, and the compounds shown in formulas (Xb) and (Xc) above have an olivine structure. These lithium-containing compounds may be substances formed by replacing a portion of a transition metal element with Al, Mg, or other transition metal elements for purposes such as structural stabilization; substances containing these metal elements at grain boundaries; substances formed by replacing a portion of oxygen atoms with fluorine atoms, etc.; and substances formed by covering at least a portion of the surface of a positive electrode active material with other positive electrode active materials.

[0200] As the positive electrode active material in this embodiment, a lithium-containing compound as described above may be used alone, or other positive electrode active materials may be used in combination with the lithium-containing compound.

[0201] Other examples of such positive electrode active materials include, for instance, metal oxides or metal chalcogenides with tunnel and layered structures; sulfur; and conductive polymers. Examples of metal oxides or metal chalcogenides with tunnel and layered structures include, for instance, MnO2, FeO2, FeS2, V2O5, and V6O. 13Oxides, sulfides, and selenides of metals other than lithium, such as TiO2, TiS2, MoS2, and NbSe2. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, and polypyrrole.

[0202] The other positive electrode active materials mentioned above can be used alone or in combination of two or more, without particular restrictions. However, from the viewpoint of being able to reversibly and stably absorb and release lithium ions and achieve high energy density, the positive electrode active material layer preferably contains at least one transition metal element selected from Ni, Mn and Co.

[0203] When lithium-containing compounds and other positive electrode active materials are used in combination as positive electrode active materials, the ratio of the two used is preferably 80% by mass or more, more preferably 85% by mass or more, as the ratio of the lithium-containing compounds used relative to the total positive electrode active materials.

[0204] Examples of conductive additives include carbon black, such as graphite, acetylene black, and Ketjen black; and carbon fiber. The proportion of the conductive additive relative to 100 parts by mass of the positive electrode active material is preferably 10 parts by mass or less, more preferably 1 to 5 parts by mass.

[0205] Examples of binders include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid, styrene-butadiene rubber, and fluororubber. The binder content relative to 100 parts by mass of the positive electrode active material is preferably 6 parts by mass or less, more preferably 0.5 to 4 parts by mass.

[0206] The positive electrode active material layer is formed as follows: a positive electrode mixture, consisting of a positive electrode active material and, as needed, a conductive additive and a binder, is dispersed in a solvent; the resulting slurry containing the positive electrode mixture is coated onto the positive electrode current collector and dried (solvent removed); and then pressed as needed to form the layer. There are no particular limitations on the solvent used; existing known solvents can be used. Examples include N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, and water.

[0207] The positive current collector is made of metal foil such as aluminum foil, nickel foil, or stainless steel foil. The positive current collector may have a carbon coating on its surface or be processed into a mesh shape. The thickness of the positive current collector is preferably 5–40 μm, more preferably 7–35 μm, and even more preferably 9–30 μm.

[0208] In this embodiment, the non-aqueous secondary battery preferably has a positive electrode active material layer with a surface weight of 15–100 mg / cm³. 2The range is defined as follows: From the viewpoint of improving the volumetric energy density of non-aqueous secondary batteries while maintaining a balance with output performance, the preferred weight per unit area is 24–100 mg / cm³. 2 More preferably 25–80 mg / cm³ 2 More preferably 26–60 mg / cm³ 2 The non-aqueous secondary battery in this embodiment can use an electrolyte with an ionic conductivity of 10 mS / cm or higher. Therefore, by designing an electrode active material layer with a high volumetric energy density, a non-aqueous secondary battery that achieves high output performance can also be provided.

[0209] <3. Negative electrode and negative current collector>

[0210] The negative electrode 160 consists of a negative electrode current collector and a layer of negative electrode active material made by a negative electrode binder. The negative electrode 160 can function as the negative electrode in non-aqueous secondary batteries.

[0211] The negative electrode active material layer contains negative electrode active material, and preferably contains conductive additives and binders as needed.

[0212] Examples of anode active materials include amorphous carbon (hard carbon), artificial graphite, natural graphite, graphite, pyrolytic carbon, coke, glassy carbon, calcined organic polymers, mesophase carbon microspheres, carbon fibers, activated carbon, graphite, carbon colloids, and carbon black, as well as metallic lithium, metal oxides, metal nitrides, lithium alloys, tin alloys, silicon alloys, intermetallic compounds, organic compounds, inorganic compounds, metal complexes, and organic polymers. Anode active materials can be used alone or in combination of two or more.

[0213] For the negative electrode active material layer, from the viewpoint of increasing battery voltage, it is preferable to contain materials that can achieve a voltage ratio of 0.4V vs. Li / Li. + Materials that absorb lithium ions at low potentials are used as negative electrode active materials.

[0214] From the viewpoint of energy density, the negative electrode preferably contains graphite or at least one element selected from the group consisting of Ti, V, Sn, Cr, Mn, Fe, Co, Ni, Zn, Al, Si, and B. From the viewpoint of electrochemical stability, the aforementioned negative electrode more preferably contains graphite.

[0215] Examples of conductive additives include carbon black, such as graphite, acetylene black, and Ketjen black; and carbon fiber. The proportion of the conductive additive relative to 100 parts by mass of the negative electrode active material is preferably 20 parts by mass or less, more preferably 0.1 to 10 parts by mass.

[0216] Examples of binders include carboxymethyl cellulose, PVDF, PTFE, polyacrylic acid, and fluororubber. Diene-based rubbers, such as styrene-butadiene rubber, can also be used. The binder content relative to 100 parts by weight of the negative electrode active material is preferably 10 parts by weight or less, more preferably 0.5 to 6 parts by weight.

[0217] The negative electrode active material layer is formed as follows: a negative electrode mixture, consisting of a negative electrode active material and, as needed, a conductive additive and a binder, is dispersed in a solvent; the resulting slurry containing the negative electrode mixture is coated onto the negative electrode current collector and dried (solvent removed); and then pressed as needed to form the layer. There are no particular limitations on the solvent used; existing known solvents can be used. Examples include N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, and water.

[0218] The negative electrode current collector is made of metal foil such as copper foil, nickel foil, or stainless steel foil. Alternatively, a carbon coating can be applied to the surface of the negative electrode current collector, or it can be processed into a mesh shape. The thickness of the negative electrode current collector is preferably 5–40 μm, more preferably 6–35 μm, and even more preferably 7–30 μm.

[0219] <5. Separator>

[0220] From the viewpoint of providing safety features such as short-circuit prevention and shutdown for the positive electrode 150 and negative electrode 160, the non-aqueous secondary battery 100 in this embodiment preferably includes a separator 170 between the positive electrode 150 and the negative electrode 160. The separator 170 is not limited and can be the same as those used in known non-aqueous secondary batteries; however, an insulating film with high ion permeability and excellent mechanical strength is preferred. Examples of separators 170 include woven fabric, non-woven fabric, and microporous membranes made of synthetic resin; among these, microporous membranes made of synthetic resin are preferred.

[0221] As for synthetic resin-based microporous membranes, polyolefin-based microporous membranes, such as those containing polyethylene or polypropylene as the main component or those containing the above two polyolefins, are suitable. Examples of nonwoven fabrics made of heat-resistant resins, such as those made of glass, ceramics, polyolefins, polyesters, polyamides, liquid crystal polyesters, and aromatic polyamides, are also suitable.

[0222] The separator 170 can be a structure formed by stacking one or more layers of a single type of microporous membrane, or a structure formed by stacking two or more types of microporous membranes. The separator 170 can also be a structure formed by stacking one or more layers of a mixed resin material obtained by melt-blending two or more resin materials.

[0223] To impart functionality, inorganic particles can be present on the surface or inside of the separator, or other organic layers can be further coated or laminated. While the inventors of this application previously filed Patent Document 3, which used acetonitrile as a non-aqueous solvent to improve the ionic conductivity of the non-aqueous electrolyte, the mainstream approach for automotive battery packs is to use coated separators in the engine compartment for safety advantages. This application completely disregards the crucial fundamental property of impermeability into the coated separator, and all non-aqueous solvents used in its embodiments are polar solvents. No measures are mentioned regarding the solubility of redox shuttles, which exhibit a significant tendency towards poor solubility due to intermolecular interactions of the π-conjugated plane, and their impermeability into the coated separator; this presents a challenge in terms of practical performance.

[0224] In addition, to impart functionality, the separator may include a cross-linked structure. These methods can be combined as needed to improve the safety performance of non-aqueous secondary batteries.

[0225] By using such a separator 170, the excellent input / output characteristics and low self-discharge characteristics required for lithium-ion batteries used in the aforementioned high-output applications can be achieved. The thickness of the microporous membrane is not particularly limited, but from the viewpoint of membrane strength, it is preferably 1 μm or more, and from the viewpoint of permeability, it is preferably 500 μm or less. From the viewpoint of high-output applications such as safety testing where heat generation is high and higher than previous self-discharge characteristics are required, and from the viewpoint of winding performance when winding with a large battery winding machine, it is preferably 5 μm or more and 30 μm or less, more preferably 10 μm or more and 25 μm or less. It should be noted that, when considering both short-circuit withstand performance and output performance, it is further preferred to be 15 μm or more and 25 μm or less, and when considering both high energy density and output performance, it is further preferred to be 10 μm or more and less than 15 μm. From the viewpoint of following the rapid movement of lithium ions at high output, the porosity is preferably 30% or more and 90% or less, more preferably 35% or more and 80% or less, and even more preferably 40% or more and 70% or less. It should be noted that, while ensuring safety and prioritizing improved output performance, a porosity of 50% or more and 70% or less is particularly preferred; and while balancing short-circuit withstand performance and output performance, a porosity of 40% or more and less than 50% is particularly preferred. From the viewpoint of balancing film thickness and porosity, the air permeability is preferably 1 second / 100cm². 3 Above 400 seconds / 100cm 3 Hereinafter, 100 seconds / 100cm is preferred. 3 Above and 350 / 100cm 3 The following should be noted: While balancing short-circuit withstand performance and output performance, a value of 150 seconds / 100cm is particularly preferred. 3Above and 350 seconds / 100cm 3 From the perspective of ensuring safety and prioritizing improved output performance, 100 / 100cm is particularly preferred. 3 More than 150 seconds / 100cm 3 On the other hand, when a non-aqueous electrolyte with low ionic conductivity is combined with a separator within the aforementioned range, the migration speed of lithium ions is limited by the ionic conductivity of the non-aqueous electrolyte, rather than by the structure of the separator, and there is a tendency to fail to obtain the desired input-output characteristics. Therefore, the ionic conductivity of the non-aqueous electrolyte is preferably 10 mS / cm or more, more preferably 15 mS / cm, and even more preferably 20 mS / cm.

[0226] It should be noted that when the ionic conductivity is 10 mS / cm or higher, lithium-ion conduction within the electrode active material layer can proceed sufficiently, thus enabling charging and discharging with high current. Furthermore, there is no particular upper limit to the ionic conductivity. From the viewpoint of suppressing unpredictable battery degradation such as dissolution and stripping degradation of various battery components, the ionic conductivity is preferably 50 mS / cm or lower, more preferably 49 mS / cm or lower, and even more preferably 48 mS / cm or lower. Here, the ionic conductivity of the electrolyte can be controlled, for example, by adjusting the viscosity and / or polarity of the non-aqueous solvent. More specifically, by mixing a low-viscosity non-aqueous solvent with a high-polarity non-aqueous solvent, the ionic conductivity of the electrolyte can be controlled to be relatively high. Alternatively, by using a non-aqueous solvent with low viscosity and high polarity, the ionic conductivity of the electrolyte can also be controlled to be relatively high. By having high ionic conductivity, and thus designing an electrode active material layer with high volumetric energy density, high output performance can also be achieved. However, the membrane thickness, air permeability and porosity of the separator, as well as the ionic conductivity of the non-aqueous electrolyte, are not limited to the examples above.

[0227] <5. Battery casing>

[0228] The structure of the battery casing 110 of the non-aqueous secondary battery 100 in this embodiment is not particularly limited. For example, either a battery can or a laminated film casing can be used. As a battery can, for example, a metal can formed of steel, stainless steel, aluminum, or a cladding material, in the shape of a square, cylindrical, oval, flat, coin-shaped, or button-shaped container, can be used. As a laminated film casing, for example, a laminated film formed of a three-layer structure of hot-melt resin / metal film / resin can be used.

[0229] Regarding the laminated film housing, two sheets can be overlapped with the hot-melt resin side facing inwards, or bent in such a way that the hot-melt resin side faces inwards, and the ends are sealed by heat sealing. The housing is then manufactured and used in this manner. When using the laminated film housing, a positive lead 130 (or a positive terminal and a lead tab connected to the positive terminal) can be connected to the positive current collector, and a negative lead 140 (or a negative terminal and a lead tab connected to the negative terminal) can be connected to the negative current collector. In this case, the laminated film housing can be sealed with the ends of the positive lead 130 and the negative lead 140 (or the lead tabs connected to the positive and negative terminals, respectively) extended to the outside of the housing.

[0230] <Manufacturing Method of Battery Pack>

[0231] Another embodiment of the present invention is a method for manufacturing a battery pack, characterized in that it is a method for manufacturing a battery pack comprising a non-aqueous secondary battery, wherein the non-aqueous secondary battery includes a positive electrode, a negative electrode, and a non-aqueous electrolyte containing an electrolyte salt and a non-aqueous solvent, and the manufacturing method includes the following steps:

[0232] The laminate formation process forms a laminate comprising the aforementioned positive electrode and the aforementioned negative electrode;

[0233] The aforementioned manufacturing process of the non-aqueous secondary battery involves housing and sealing the aforementioned laminate and the aforementioned non-aqueous electrolyte within a battery casing; and

[0234] The battery pack is constructed by connecting one or more modules consisting of two or more non-aqueous secondary batteries connected in series in parallel, or by connecting two or more modules consisting of two or more non-aqueous secondary batteries connected in parallel in series.

[0235] The ratio of the maximum capacity (B) to the minimum capacity (A) of each non-aqueous secondary battery constituting the aforementioned module is 1.00 < B / A < 2.00, and the aforementioned non-aqueous electrolyte contains a redox shuttle that has a reversible redox potential at a potential higher than the positive electrode potential when fully charged.

[0236] The aforementioned manufacturing method preferably further includes a charging step, which performs an initial charge on the aforementioned non-aqueous secondary battery at a charge rate of 0.001 to 0.3C.

[0237] <6. Battery Manufacturing Method>

[0238] The non-aqueous secondary battery 100 in this embodiment can be manufactured using the aforementioned non-aqueous electrolyte, a positive electrode 150 having a positive active material layer on one or both sides of the current collector, a negative electrode 160 having a negative active material layer on one or both sides of the current collector, a battery casing 110, and a separator 170 as needed, using the aforementioned manufacturing method and known methods.

[0239] First, a laminate containing a positive electrode 150 and a negative electrode 160, and a separator 170 as needed, is formed (laminate formation process). For example, it can be formed in the following ways: by winding a strip of positive electrode 150 and negative electrode 160 in a laminated state with a separator sandwiched between them, forming a wound laminate; by cutting the positive electrode 150 and negative electrode 160 into multiple sheets with a certain area and shape, and alternately stacking the resulting positive and negative electrode sheets with separator sheets, forming a laminate; by bending the strip of separator multiple times in a "Z" shape, and alternately inserting positive and negative electrode sheets between the bent "Z" shapes, forming a laminate; etc.

[0240] Next, in the manufacturing process of the non-aqueous secondary battery, the above-mentioned laminate is housed in the battery casing 110 (battery housing), and the non-aqueous electrolyte of this embodiment is injected into the battery housing, so that the laminate is immersed in the non-aqueous electrolyte and sealed, thereby manufacturing the non-aqueous secondary battery of this embodiment.

[0241] Alternatively, a non-aqueous electrolyte can be impregnated into a substrate formed of a polymer material to pre-prepare a gel-state electrolyte membrane. After forming a laminated structure using sheet-like positive electrode 150, negative electrode 160, electrolyte membrane, and separators 170 as needed, the laminated structure is housed within a battery casing 110 to produce a non-aqueous secondary battery 100.

[0242] It should be noted that if the electrode configuration is such that the outer periphery of the negative electrode active material layer overlaps with the outer periphery of the positive electrode active material layer, or if there is an excessively narrow portion in the non-opposite portion of the negative electrode active material layer, electrode misalignment may occur during battery assembly, thereby reducing the charge-discharge cycle characteristics of the non-aqueous secondary battery. Therefore, the electrode body used in this non-aqueous secondary battery is preferably pre-fixed in position using tapes such as polyimide tape, polyphenylene sulfide tape, and PP tape, or adhesives.

[0243] In this embodiment, when using a non-aqueous electrolyte containing acetonitrile, due to its high ionic conductivity, lithium ions released from the positive electrode during the first charge of the non-aqueous secondary battery may diffuse throughout the negative electrode. For non-aqueous secondary batteries, the area of ​​the negative electrode active material layer is typically larger than that of the positive electrode active material layer. However, if lithium ions diffuse and are absorbed into areas of the negative electrode active material layer that do not face the positive electrode active material layer, these lithium ions will not be released during the first discharge and will remain at the negative electrode. Therefore, the contribution of these unreleased lithium ions constitutes irreversible capacity. For this reason, the initial charge-discharge efficiency may be reduced for non-aqueous secondary batteries using a non-aqueous electrolyte containing acetonitrile.

[0244] On the other hand, if the area of ​​the positive electrode active material layer is larger than that of the negative electrode active material layer, or if the two are the same, current concentration is more likely to occur at the edge of the negative electrode active material layer during charging, which can easily lead to the formation of lithium dendrites.

[0245] There is no particular limitation on the ratio of the total area of ​​the negative electrode active material layer to the area of ​​the portion of the positive electrode active material layer opposite to the negative electrode active material layer. However, for the reasons mentioned above, it is preferable to be greater than 1.0 and less than 1.1, more preferably greater than 1.002 and less than 1.09, even more preferably greater than 1.005 and less than 1.08, and particularly preferably greater than 1.01 and less than 1.08. For non-aqueous secondary batteries using non-aqueous electrolytes containing acetonitrile, reducing the ratio of the total area of ​​the negative electrode active material layer to the area of ​​the portion of the positive electrode active material layer opposite to the negative electrode active material layer can improve the initial charge-discharge efficiency.

[0246] Reducing the ratio of the total area of ​​the negative electrode active material layer to the area of ​​the portion of the positive electrode active material layer opposite to it means limiting the proportion of the area of ​​the negative electrode active material layer that does not face the positive electrode active material layer. This minimizes the amount of lithium ions released from the positive electrode during the first charge that are absorbed into the portion of the negative electrode active material layer that does not face the positive electrode active material layer (i.e., the amount of lithium ions that do not release from the negative electrode during the first discharge and form irreversible capacity). Therefore, by designing the ratio of the total area of ​​the negative electrode active material layer to the area of ​​the portion of the positive electrode active material layer opposite to it within the aforementioned range, the load characteristics of the battery using acetonitrile are improved, the first charge / discharge efficiency of the battery is increased, and the formation of lithium dendrites can be suppressed.

[0247] The non-aqueous secondary battery 100 in this embodiment can function as a battery upon initial charging, stabilizing itself through the decomposition of a portion of the non-aqueous electrolyte during the first charge. There are no particular limitations on the method of the first charge; preferably, it is performed at 0.001–0.3C, more preferably at 0.002–0.25C, and even more preferably at 0.003–0.2C. Performing the first charge via constant voltage charging also yields preferred results. The designed capacity is achieved with a constant current of 1C for 1 hour of discharge. By setting a longer voltage range for the lithium salt to participate in the electrochemical reaction, a stable and robust SEI is formed on the electrode surface, suppressing the increase in internal resistance. Furthermore, the reaction products are not only firmly immobilized on the negative electrode 160, but also have a beneficial effect on components other than the negative electrode 160, such as the positive electrode 150 and the separator 170. Therefore, considering the electrochemical reaction of the lithium salt dissolved in the non-aqueous electrolyte during the first charge is highly effective.

[0248] The non-aqueous secondary battery 100 in this embodiment can also be used in the form of a battery pack consisting of multiple non-aqueous secondary batteries 100 connected in series or in parallel. From the viewpoint of managing the charge and discharge state of the battery pack, the operating voltage range of each battery is preferably 2 to 5V, more preferably 2.5 to 5V, and particularly preferably 2.75V to 5V.

[0249] <7. Modules and Battery Packs (Construction Process)>

[0250] The non-aqueous secondary battery of this embodiment is used in the form of a module in which multiple units of two or more cells are connected in series or in parallel. Furthermore, the module is used in the form of a battery pack containing one or more modules. Specifically, the aforementioned battery pack is constructed by connecting one or two or more modules of the aforementioned non-aqueous secondary batteries, which are connected in series, in parallel, or by connecting two or more modules of the aforementioned non-aqueous secondary batteries, which are connected in parallel, in series. Figure 3 A circuit diagram of an example of the battery pack according to this embodiment is provided for illustrative purposes. It should be noted that, from the viewpoint of managing the charge and discharge states of the battery pack, the operating voltage range for each battery is preferably 2 to 5V, more preferably 2 to 4.3V, and particularly preferably 2V to 3.9V. Furthermore, from the viewpoint of improving battery yield, the capacity of the aforementioned non-aqueous secondary battery constituting the aforementioned module is preferably 1mAh or more and 100Ah or less.

[0251] The ratio of the maximum capacity (B) to the minimum capacity (A) of each non-aqueous secondary battery constituting the aforementioned module is 1.00 < B / A < 2.00. Here, the minimum and maximum capacities in this embodiment are defined by the charging current capacity planned for a single cell state. Specifically, this is obtained by subtracting the charging current capacity equivalent to the current SOC (State of Charge) from the fully charged current capacity determined through charging and discharging before constituting the module. Alternatively, the minimum and maximum capacities in this embodiment can be determined by removing each non-aqueous secondary battery from the module and measuring their charging current capacity. Here, the fully charged current capacity refers to the capacity of the non-aqueous secondary battery when the SOC is 100%. That is, the fully charged current capacity is the battery capacity designed through the positive and negative terminals, referred to as the "design capacity" in this embodiment.

[0252] Furthermore, the minimum capacity (A) and maximum capacity (B) of this embodiment are preferably the capacities when forming modules.

[0253] The battery pack of this embodiment contains acetonitrile and chain carbonate in a non-aqueous solvent, thereby enabling the redox shuttle with a specific structure to function fully. Therefore, even when multiple non-aqueous secondary batteries with different capacities are connected, balance deviations between the non-aqueous secondary batteries can be eliminated when charging at high current densities. Furthermore, the battery pack includes an imide salt and LiPF6 as the electrolyte salt, with the imide salt content being 0.5 mol to 3 mol per 1 L of the non-aqueous solvent, and the molar ratio in the non-aqueous electrolyte being LiPF6 < imide salt. This further eliminates balance deviations between the non-aqueous secondary batteries during charging at low to high temperatures, providing a high-capacity battery pack with stable charge-discharge cycles. The battery pack of this embodiment can suppress overcharge degradation; therefore, even if the ratio of the maximum capacity (B) to the minimum capacity (A) of the aforementioned non-aqueous secondary batteries is 1.05 < B / A < 2.00, it still exhibits the unique effect of eliminating balance deviations between the non-aqueous secondary batteries.

[0254] The design capacity of each non-aqueous secondary battery constituting the aforementioned battery pack can be measured by discharging it to the rated voltage at SOC = 0% with a constant current and then fully charging it with a constant voltage. Because the battery pack of this embodiment can suppress overcharge degradation, it exhibits a unique effect of eliminating balance deviations among the non-aqueous secondary batteries, even if the ratio of the maximum design capacity (D) to the minimum design capacity (C) of the aforementioned non-aqueous secondary batteries is 1.05 < D / C < 2.00.

[0255] <8. Application>

[0256] The redox shuttle of this embodiment can be used as follows. That is,

[0257] The compound represented by the following general formula (1) is used as a redox shuttle in a battery pack having a non-aqueous secondary battery, wherein the non-aqueous secondary battery comprises a positive electrode, a negative electrode, and a non-aqueous electrolyte containing an electrolyte salt and a non-aqueous solvent.

[0258]

[0259] {In equation (1), R} 1 R 2 R 3 R 4 R 5 and R 6 The substituents shown are independently hydrogen atoms, halogen atoms, aryl groups, alkyl groups having 1 to 4 carbon atoms, fluoro-substituted alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms, wherein two or more of these substituents are alkoxy groups having 1 to 4 carbon atoms or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms.

[0260] The battery pack is formed by connecting one or more modules consisting of two or more non-aqueous secondary batteries connected in series in parallel, or the battery pack is formed by connecting two or more modules consisting of two or more non-aqueous secondary batteries connected in parallel in series in series. The ratio of the maximum capacity (B) of each non-aqueous secondary battery constituting the module to the minimum capacity (A) is 1.00 < B / A < 2.00.

[0261] The application method is the same as that in <1. Non-aqueous electrolyte> through <7. Modules and battery packs>.

[0262] The methods for implementing the present invention have been described above, but the present invention is not limited to the above embodiments. Various modifications can be made to the present invention without departing from its spirit.

[0263] Example

[0264] The present invention will be specifically described below through examples, but the present invention is not limited to these examples. It should be noted that various characteristics of non-aqueous secondary batteries and battery packs are measured and evaluated as follows.

[0265] [Examples 1-3, Comparative Examples 1-3]

[0266] (1) Preparation and solubility determination of non-aqueous electrolytes

[0267] In an inactive atmosphere at 25°C, various non-aqueous solvents and various lithium salts were mixed to achieve specified concentrations, and then various lithium salts and redox shuttles were added to achieve specified concentrations, thereby preparing non-aqueous electrolytes (S1) to (S5). The composition of these non-aqueous electrolytes and the presence or absence of dissolved residues of the redox shuttles are shown in Table 1 below.

[0268] The abbreviations for non-aqueous solvents, electrolyte salts, and redox shuttles in Table 1 below have the following meanings. Additionally, the mass percentage of redox shuttles in Table 1 represents the mass percentage relative to the total amount of the non-aqueous electrolyte. Volume percentage and mass percentage can be converted using the specific gravity (25°C) values ​​of each non-aqueous solvent, electrolyte salt, and redox shuttle.

[0269] (Non-aqueous solvents)

[0270] AcN: Acetonitrile

[0271] EMC: Ethyl methyl carbonate

[0272] GBL: γ-Butyrolactone

[0273] PC: Propylene carbonate

[0274] EC: Ethylene carbonate

[0275] VC: Vinylene carbonate

[0276] ES: Ethyl sulfite

[0277] (electrolyte salts)

[0278] LiPF6: Lithium hexafluorophosphate

[0279] LiFSI: Lithium bis(fluorosulfonyl)imide (LiN(SO2F)2)

[0280] (Redox shuttle)

[0281] DDB: 1,4-Di-tert-butyl-2,5-dimethoxybenzene

[0282] DDFB: 1,4-Di-tert-butyl-2,5-bis(2,2,2-trifluoroethoxy)benzene

[0283] (2) Determination of ionic conductivity of non-aqueous electrolytes

[0284] A non-aqueous electrolyte was prepared in a polypropylene container. An ionic conductivity measuring battery, CT-57101B (trade name), manufactured by DKK Corporation, connected to an ionic conductivity meter "CM-30R" (trade name) manufactured by DKK Corporation, was inserted into the container containing the non-aqueous electrolyte. The ionic conductivity of the non-aqueous electrolyte was measured at 25°C. These results are shown in Table 1 below.

[0285] (3) Determination of the permeability of separators for non-aqueous electrolytes

[0286] Weigh 200 μL of the non-aqueous electrolyte obtained as described above using a pipette, and add it dropwise to the inorganic oxide particle-coated polyolefin separator [HIPORE] manufactured by Asahi Kasei Corporation. TM On (product name). Those that completed the penetration within 1 second were marked "○", and those that failed to penetrate within 1 second due to surface tension were marked "×". These results are shown in Table 1 below.

[0287] [Table 1]

[0288]

[0289] [Example 4]

[0290] (4) 25℃ series evaluation (SOC adjustment of non-aqueous secondary battery)

[0291] (4-1) Fabrication of the positive electrode (LP1) with leads

[0292] LiFePO4 as the positive electrode active material, acetylene black powder as a conductive additive, and polyvinylidene fluoride (PVdF) as a binder were mixed at a mass ratio of 85:8:7 to obtain a positive electrode mixture. N-methyl-2-pyrrolidone as a solvent was added to the obtained positive electrode mixture and further mixed to prepare a slurry containing the positive electrode mixture. On one side of an aluminum foil with a thickness of 15 μm and a width of 280 mm, which serves as the positive electrode current collector, the slurry containing the positive electrode mixture was coated using a 3-roll transfer coating machine while adjusting the unit area weight of the slurry, thus forming a coating pattern with a coating width of 240–250 mm, a coating length of 125 mm, and an uncoated length of 20 mm. The solvent was removed by drying in a hot air drying oven. The resulting electrode roll was trimmed at both ends and subjected to reduced pressure drying at 130°C for 8 hours. Afterwards, the positive electrode active material layer was rolled to achieve a density of 1.84 g / cm³. 3 The positive electrode (P1) is obtained by calendering, consisting of a positive active material layer and a positive current collector. The weight per unit area of ​​the positive active material layer is 13.6 mg / cm³. 2 .

[0293] Then, the positive electrode (P1) is cut so that the area of ​​the positive electrode compound layer is 30mm × 50mm and includes the exposed portion of the aluminum foil. Then, aluminum lead sheets for taking out current are welded to the exposed portion of the aluminum foil, and vacuum dried at 170°C for 10 hours to obtain the leaded positive electrode (LP1).

[0294] (4-2) Fabrication of the leaded negative electrode (LN1)

[0295] Artificial graphite powder (MCMB) as the negative electrode active material, acetylene black powder as a conductive additive, and polyvinylidene fluoride (PVdF) as a binder were mixed at a solid component mass ratio of 93:2:5 to obtain a negative electrode mixture. N-methyl-2-pyrrolidone was added as a solvent to the obtained negative electrode mixture and further mixed to prepare a slurry containing the negative electrode mixture. On one side of a copper foil with a thickness of 8 μm and a width of 280 mm, which serves as the negative electrode current collector, the slurry containing the negative electrode mixture was coated using a 3-roll transfer coating machine while adjusting the unit area weight of the slurry, thus forming a coating pattern with a coating width of 240–250 mm, a coating length of 125 mm, and an uncoated length of 20 mm. The solvent was removed by drying in a hot air drying oven. The resulting electrode roll was trimmed at both ends and subjected to reduced pressure drying at 80°C for 12 hours. Afterwards, it was rolled to achieve a negative electrode active material layer density of 1.28 g / cm³. 3 The negative electrode (N1) is obtained by calendering, consisting of a negative electrode active material layer and a negative electrode current collector. The weight per unit area of ​​the negative electrode active material layer is 6.1 mg / cm³. 2 .

[0296] Then, the negative electrode (N1) is cut so that the area of ​​the negative electrode compound layer is 32mm × 52mm and includes the exposed portion of copper foil. Then, nickel lead sheets for taking out current are soldered to the exposed portion of copper foil, and vacuum drying is performed at 170°C for 10 hours, thereby obtaining the leaded negative electrode (LN1).

[0297] (4-3) Fabrication of a single-layer laminated non-aqueous secondary battery

[0298] A polyolefin separator [HIPORE] is coated with leaded positive electrode (LP1) and leaded negative electrode (LN1) facing each other with their respective coatings, separated by inorganic oxide particles. TM (Product Name) (Thickness 21μm, Breathability 80 seconds / 100cm) 3 The electrodes are stacked to form a laminated electrode body. This laminated electrode body is housed in a 100mm × 90mm aluminum laminate shell and vacuum-dried at 80°C for 5 hours to remove moisture. Then, the above-mentioned non-aqueous electrolyte (S1) is injected into the shell and the shell is sealed, thereby fabricating a single-layer laminated (pouch-type) non-aqueous secondary battery.

[0299] (4-4) SOC Adjustment of Single-Layer Laminated Non-Aqueous Secondary Batteries

[0300] For the single-layer laminated non-aqueous secondary battery obtained as described above, the first charge treatment is performed according to the steps in (4-4-1) below. Then, the SOC of the single-layer laminated non-aqueous secondary battery is adjusted according to the steps in (4-4-2) below.

[0301] (4-4-1) First charge-discharge treatment of single-layer laminated non-aqueous secondary batteries

[0302] The ambient temperature of the single-layer laminated non-aqueous secondary battery was set to 25°C. After charging at a constant current of 0.025C for 2 hours, it was allowed to rest for 3 hours, then charged at a constant current of 0.05C until it reached 3.7V. Afterward, it was charged at a constant voltage of 3.7V until the current decreased to 0.02C. Finally, it was discharged at a constant current of 0.05C to 2.0V. Two single-layer laminated non-aqueous secondary batteries were prepared using the same procedure.

[0303] (4-4-2) SOC Adjustment of Single-Layer Laminated Non-Aqueous Secondary Batteries

[0304] The ambient temperature of the single-layer laminated non-aqueous secondary battery obtained in (4-4-1) was set to 25°C, and it was charged with a constant current equivalent to 0.2C, with the SOC adjusted to 65% and 35% respectively.

[0305] (4-5) Fabrication and charge / discharge evaluation of the series module

[0306] A module was fabricated by connecting a single-layer laminated non-aqueous secondary battery with a SOC of 65% and a single-layer laminated non-aqueous secondary battery with a SOC of 35% in series, as obtained in (4-4-2). It should be noted that the ratio of the maximum capacity (14.6 mAh) to the minimum capacity (7.9 mAh) of the non-aqueous secondary battery constituting the aforementioned module is 1.85. The ambient temperature of the resulting series module was set to 25°C. After reaching 7.4V with a constant current of 0.2C, it was charged with a constant voltage of 7.4V for a total charging time of 5.5 hours or until the current decreased to 0.05C. Then, it was discharged to 4.0V with a constant current equivalent to 0.2C. Next, it was charged to 7.4V with a constant current of 0.2C and a constant voltage of 7.4V for a total charging time of 8 hours or until the current decreased to 0.05C. Finally, it was discharged to 4.0V with a constant current equivalent to 0.2C. The results are shown in Tables 2 and 3 below.

[0307] When a non-aqueous secondary battery is initially adjusted to a SOC of 65%, an initial voltage rise occurs. However, due to the high ion conductivity, the redox shuttle functions effectively, and the voltage plateaus around 3.8V for a single cell, suppressing further voltage increases. Furthermore, a non-aqueous secondary battery initially adjusted to a SOC of 35% reaches near-fully charged status while another non-aqueous secondary battery plateaus around 3.8V. Moreover, in the second cycle, both non-aqueous secondary batteries exhibit almost identical charge-discharge behavior. This demonstrates that the state of single cells at different SOCs is corrected.

[0308] [Comparative Example 4]

[0309] The non-aqueous electrolyte (S1) of Example 4 was used as (S2), and the series battery was fabricated / evaluated using the same steps as in Example 4. It should be noted that the ratio of the maximum capacity (14.7 mAh) to the minimum capacity (7.9 mAh) of the non-aqueous secondary battery constituting the aforementioned module was 1.86. The results are shown in Tables 2 and 3 below.

[0310] When a non-aqueous secondary battery is initially adjusted to a SOC of 65%, a voltage rise occurs first, with the charging voltage exceeding 4V. Therefore, the charge / discharge program switches to constant voltage conditions when the voltage reaches 7.4V (based on a single-cell series connection). Consequently, batteries initially adjusted to a SOC of 35% are charged at around 3.4V. Furthermore, during discharge, batteries initially adjusted to a SOC of 35% are in an over-discharge state significantly below 2.0V.

[0311] [Example 5]

[0312] (5) -10℃ series evaluation (SOC adjustment of non-aqueous secondary battery)

[0313] (5-1) Fabrication of a single-layer laminated non-aqueous secondary battery

[0314] The aforementioned positive electrode (LP1) and negative electrode (LN1) with leads are coated with a polyolefin separator [HIPORE] with their respective electrode coating surfaces facing each other, separated by inorganic oxide particles. TM (Product Name) (Thickness 21μm, Breathability 80 seconds / 100cm) 3 The electrodes are stacked to form a laminated electrode body. This laminated electrode body is then housed in a 100mm × 90mm aluminum laminate shell and vacuum-dried at 80°C for 5 hours to remove moisture. Next, a non-aqueous electrolyte (S5) is injected into the shell, and the shell is sealed, thereby fabricating a single-layer laminated non-aqueous secondary battery.

[0315] (5-2) Fabrication and charge / discharge evaluation of the series module

[0316] Using the single-layer laminated non-aqueous secondary battery obtained in (5-1) above, perform the first charge treatment according to the steps in (4-4-1) above, except that. Then, adjust the SOC of the single-layer laminated non-aqueous secondary battery according to the steps in (4-4-2). Connect the single-layer laminated non-aqueous secondary battery with an SOC of 65% and a single-layer laminated non-aqueous secondary battery with an SOC of 35% in series to create a module. It should be noted that the ratio of the maximum capacity (15.4mAh) to the minimum capacity (8.3mAh) of the non-aqueous secondary battery constituting the aforementioned module is 1.86. Set the ambient temperature of the obtained series module to -10°C, and charge it to 7.4V with a constant current of 0.1C, then charge it at a constant voltage of 7.4V for a total charging time of 11 hours or until the current decreases to 0.05C. Afterward, discharge it to 4.0V with a constant current equivalent to 0.1C. Then, after reaching 7.4V with a constant current of 0.1C, charging was performed at a constant voltage of 7.4V to achieve a total charging time of 16 hours or to allow the current to decay to 0.05C. Afterwards, discharge was performed with a constant current equivalent to 0.1C to 4.0V. The results are shown in Tables 2 and 3 below.

[0317] When the non-aqueous secondary battery was initially adjusted to a SOC of 65%, an initial voltage rise occurred. However, even at low temperatures, the redox shuttle functioned effectively, and the voltage plateaued around 3.8V for a single cell, suppressing further voltage increases. Conversely, when the non-aqueous secondary battery was initially adjusted to a SOC of 35%, it reached a nearly fully charged state while another non-aqueous secondary battery was plateauing around 3.8V. Furthermore, in the second cycle, both batteries exhibited almost identical charge-discharge behavior. This demonstrates that the state of single cells at different SOCs was corrected.

[0318] [Comparative Example 5]

[0319] Ethylene carbonate, ethyl methyl carbonate, and vinylene carbonate were mixed in a volume ratio of 29:69:2, and 1 mol of LiPF6 was dissolved in 1 L of the resulting solvent to obtain a non-aqueous electrolyte (SO).

[0320] The non-aqueous electrolyte (S5) of Example 5 was used as (S0), and the series battery was fabricated / evaluated using the same steps as in Example 5. It should be noted that the ratio of the maximum capacity (15.3 mAh) to the minimum capacity (8.2 mAh) of the non-aqueous secondary battery constituting the aforementioned module is 1.87. The results are shown in Tables 2 and 3 below.

[0321] When a non-aqueous secondary battery is initially adjusted to a SOC of 65%, a voltage rise occurs first, and the charging voltage exceeds 4V. Therefore, the charge / discharge program switches to constant voltage conditions when the voltage reaches 7.4V (based on a single series cell). Thus, when a non-aqueous secondary battery is initially adjusted to a SOC of 35%, charging is maintained at around 3.4V. Furthermore, during discharge, a non-aqueous secondary battery initially adjusted to a SOC of 35% is in an over-discharge state significantly below 2.0V.

[0322] The results of Examples 4 and 5, and Comparative Examples 4 and 5 are shown in Tables 2 and 3 below. Additionally, the results of Example 4 and Comparative Example 4 are shown in Tables 2 and 3 respectively. Figure 4 and 5 .

[0323] [Table 2]

[0324] Table 2

[0325]

[0326] [Table 3]

[0327] Table 3

[0328]

[0329] [Example 6]

[0330] (6) 25℃ series evaluation (non-aqueous secondary batteries with different design capacities)

[0331] (6-1) Fabrication of the positive electrode with leads (LP2, LP3)

[0332] LiFePO4 as the positive electrode active material, carbon black powder as a conductive additive, and polyvinylidene fluoride (PVdF) as a binder were mixed at a mass ratio of 84:10:6 to obtain a positive electrode mixture. N-methyl-2-pyrrolidone as a solvent was added to the obtained positive electrode mixture and further mixed to prepare a slurry containing the positive electrode mixture. On one side of an aluminum foil with a thickness of 15 μm and a width of 280 mm, which serves as the positive electrode current collector, a 3-roll transfer coating machine was used to coat the slurry containing the positive electrode mixture, adjusting the unit area weight to obtain a coating pattern with a coating width of 240–250 mm, a coating length of 125 mm, and an uncoated length of 20 mm. The coating was then dried in a hot air drying oven to remove the solvent. The resulting electrode roll was trimmed at both ends and dried under reduced pressure at 130°C for 8 hours. Afterward, it was rolled to achieve a positive electrode active material layer density of 1.90 g / cm³. 3 The positive electrode (P2) is obtained by calendering using a method that combines a positive active material layer and a positive current collector. The surface area weight of the positive active material layer is 17.5 mg / cm³. 2.

[0333] Then, the positive electrode (P2) is cut so that the area of ​​the positive electrode compound layer is 30mm × 50mm and includes the exposed portion of the aluminum foil. Then, aluminum lead sheets for taking out current are welded onto the exposed portion of the aluminum foil, and vacuum drying is performed at 170°C for 10 hours, thereby obtaining the leaded positive electrode (LP2).

[0334] In addition, the area of ​​the positive electrode mixture layer is set to 33mm×53mm, and the leaded positive electrode (LP3) is obtained directly through the same steps as above.

[0335] (6-2) Fabrication of the leaded negative terminals (LN2, LN3)

[0336] The following materials were used: MCMB (artificial graphite powder) as the negative electrode active material, acetylene black powder as the conductive additive, a carboxymethyl cellulose (density 1.60 g / cm3) solution (solid content concentration 1.83 wt%) as the binder, and diene rubber (glass transition temperature: -5℃, number average particle size at dryness: 120 nm, density 1.00 g / cm3). 3 A negative electrode agent was prepared by mixing water and solids (40% by mass) in a solids mass ratio of 95.7:0.5:1.7:2.1. Water was added as a solvent to the negative electrode agent to achieve a solids mass of 45% by mass, and the mixture was further stirred to prepare a slurry containing the negative electrode agent. On one side of a copper foil with a thickness of 8 μm and a width of 280 mm, which serves as the negative electrode current collector, a coating pattern with a width of 240–250 mm, a coating length of 125 mm, and an uncoated length of 20 mm was applied using a 3-roll transfer coating machine while adjusting the unit area weight of the slurry containing the negative electrode agent. The coating was then dried in a hot air drying oven to remove the solvent. The resulting electrode roll was trimmed at both ends and dried under reduced pressure at 80°C for 12 hours. Afterward, it was rolled to achieve a negative electrode active material layer density of 1.5 g / cm³. 3 The negative electrode (N2) is obtained by calendering, consisting of a negative electrode active material layer and a negative electrode current collector. The weight per unit area of ​​the negative electrode active material layer is 7.5 mg / cm³. 2 .

[0337] Then, the negative electrode (N2) is cut so that the area of ​​the negative electrode compound layer is 32mm × 52mm and includes the exposed portion of copper foil. Then, nickel lead sheets for taking out current are soldered onto the exposed portion of copper foil, and vacuum drying is performed at 170°C for 10 hours, thereby obtaining the leaded negative electrode (LN2).

[0338] In addition, the area of ​​the negative electrode mixture layer is set to 35mm×55mm, and the leaded negative electrode (LN3) is obtained directly through the same steps as above.

[0339] (6-3) Fabrication of a single-layer laminated non-aqueous secondary battery

[0340] A polyolefin separator [HIPORE] is coated with leaded positive electrode (LP2) and leaded negative electrode (LN2) facing each other with their respective coatings, separated by inorganic oxide particles. TM (Product Name) (Thickness 21μm, Breathability 80 seconds / 100cm) 3 The electrode body is stacked to form a multilayer electrode. This multilayer electrode body is then housed in a 100mm × 90mm aluminum laminate shell and vacuum-dried at 80°C for 5 hours to remove moisture. Next, the aforementioned non-aqueous electrolyte (S1) is injected into the shell, and then the shell is sealed, thereby producing a single-layer laminated (pouch-type) non-aqueous secondary battery (small).

[0341] In addition, except for setting the positive electrode (LP3) and the negative electrode (LN3) with leads, a single-layer laminated (pouch-type) non-aqueous secondary battery (large) is fabricated using the same steps as described above.

[0342] (6-4) First charge-discharge treatment of single-layer laminated non-aqueous secondary batteries

[0343] The ambient temperature of the single-layer laminated non-aqueous secondary batteries (small and large) obtained as described above was set to 25°C. They were charged at a constant current of 0.025C for 2 hours, rested for 3 hours, and then charged at a constant current of 0.05C. After reaching 3.7V, they were charged at a constant voltage of 3.7V until the current decreased to 0.02C. Finally, they were discharged at a constant current of 0.05C to 2.0V.

[0344] (6-5) Fabrication and charge / discharge evaluation of the series module

[0345] A module was fabricated by connecting single-layer laminated non-aqueous secondary batteries with different design capacities obtained in (6-4) above in series. It should be noted that the ratio of the maximum capacity (36.6mAh) to the minimum capacity (31.9mAh) of the non-aqueous secondary batteries constituting the aforementioned module is 1.15. The ambient temperature of the resulting series module was set to 25°C. After reaching 7.4V with a constant current of 0.1C, it was charged with a constant voltage of 7.4V for a total charging time of 16 hours or until the current decreased to 0.05C. Then, it was discharged to 4.0V with a constant current equivalent to 0.1C. This charge-discharge cycle was performed a total of 3 times. The results are shown in Tables 4 and 5 below.

[0346] In the case of a single-layer laminated non-aqueous secondary battery (small), a voltage rise initially occurs. However, due to the high ion conductivity, the redox shuttle functions effectively even with a thick-film electrode, and the voltage plateaus around 3.8V for a single cell, suppressing further voltage increases. In the case of a single-layer laminated non-aqueous secondary battery (large), the battery reaches a nearly fully charged state while the other non-aqueous secondary battery plateaus around 3.8V. Furthermore, in the second cycle, the two non-aqueous secondary batteries exhibit almost identical charge-discharge behavior. The same results as the second cycle were obtained in the third cycle, demonstrating that the state of the single cells at different capacities was corrected.

[0347] [Example 7]

[0348] (7) 25℃ series evaluation (SOC adjustment of non-aqueous secondary batteries with different design capacities)

[0349] (7-1) SOC Adjustment of Single-Layer Laminated Non-Aqueous Secondary Batteries

[0350] After the 25°C series evaluation in (6) above, the series connection between the single-layer laminated non-aqueous secondary battery (small) and (large) was disconnected. The ambient temperature was set to 25°C, and the battery was charged with a constant current equivalent to 0.2C to adjust the SOC of the single-layer laminated non-aqueous secondary battery (small) to 60% and the SOC of the single-layer laminated non-aqueous secondary battery (large) to 40%.

[0351] (7-2) Fabrication and charge / discharge evaluation of the series module

[0352] The single-layer laminated non-aqueous secondary batteries (small and large) obtained in (7-1) with different SOCs were adjusted and then connected in series to fabricate a module. It should be noted that the ratio of the maximum capacity (22.0 mAh) to the minimum capacity (12.8 mAh) of the non-aqueous secondary batteries constituting the aforementioned module is 1.72. The ambient temperature of the resulting series-connected module was set to 25°C. After reaching 7.4V with a constant current of 0.1C, it was charged at a constant voltage of 7.4V for a total charging time of 16 hours or until the current decreased to 0.05C. Then, it was discharged to 4.0V with a constant current equivalent to 0.1C. This charge-discharge cycle was repeated a total of 3 times. The results are shown in Tables 4 and 5 below.

[0353] In the case of the small, single-layer laminated non-aqueous secondary battery, a voltage rise initially occurs. Due to the high ion conductivity, even the redox shuttle in the thick-film electrode functions effectively, and the voltage plateaus around 3.8V for a single cell, suppressing further voltage increases. Furthermore, the large, single-layer laminated non-aqueous secondary battery reaches a nearly fully charged state while another non-aqueous secondary battery reaches a plateau around 3.8V. Consequently, in the second cycle, the two non-aqueous secondary batteries exhibit almost identical charge-discharge behavior. The same results as the second cycle were obtained in the third cycle, demonstrating that the state of the single cells at different capacities was corrected.

[0354] [Example 8]

[0355] (8) 50℃ series evaluation (non-aqueous secondary batteries with different design capacities)

[0356] Following the 25°C series evaluation in (7) above, the ambient temperature of the series module was set to 50°C. After reaching 7.4V with a constant current of 0.1C, it was charged at a constant voltage of 7.4V for a total charging time of 16 hours or until the current decreased to 0.05C. Then, it was discharged to 4.0V with a constant current equivalent to 0.1C. This charge-discharge cycle was performed a total of 3 times. The results are shown in Tables 4 and 5 below.

[0357] In the case of a single-layer laminated non-aqueous secondary battery (small), a voltage rise occurs initially. Due to the high ion conductivity, even the redox shuttle in the thick-film electrode functions effectively. The voltage plateaus around 3.8V for a single cell, and further voltage rises are suppressed. In the case of a single-layer laminated non-aqueous secondary battery (large), it reaches a nearly fully charged state while the other non-aqueous secondary battery reaches a plateau around 3.8V. Furthermore, in the second cycle, the two non-aqueous secondary batteries exhibit almost identical charge-discharge behavior. The same results as the second cycle were obtained in the third cycle, demonstrating that the state of the single cells with different capacities was corrected at a temperature of 50°C.

[0358] [Example 9]

[0359] (9) Evaluation of high-rate series connection at 50℃ (non-aqueous secondary batteries with different design capacities)

[0360] Following the 50°C series evaluation in (8) above, the ambient temperature of the series module was maintained at 50°C. After reaching 7.4V with a constant current of 0.2C, it was charged at a constant voltage of 7.4V for a total charging time of 8 hours or until the current decreased to 0.05C. Then, it was discharged to 4.0V with a constant current equivalent to 0.2C. This charge-discharge cycle was performed a total of 3 times. The results are shown in Tables 4 and 5 below.

[0361] In the case of the single-layer laminated non-aqueous secondary battery (small), a voltage rise initially occurs. Due to the high ion conductivity, the redox shuttle functions effectively even with a thick-film electrode and at 0.2C, and the voltage plateaus around 3.8V for a single cell, suppressing further voltage increases. In the case of the single-layer laminated non-aqueous secondary battery (large), it reaches a nearly fully charged state while the other non-aqueous secondary battery reaches a plateau around 3.8V. Furthermore, in the second cycle, both batteries exhibit almost identical charge-discharge behavior. The same results as the second cycle were obtained in the third cycle, demonstrating that the state of single cells with different capacities is corrected even under high-rate conditions at 50°C.

[0362] The results of Examples 6-9 are shown in Tables 4 and 5 below. Figures 6-9 .

[0363] [Table 4]

[0364] Table 4

[0365]

[0366] [Table 5]

[0367] Table 5

[0368]

[0369] Industrial availability

[0370] In addition to being used as automotive batteries such as hybrid electric vehicles, plug-in hybrid electric vehicles, and electric vehicles, the non-aqueous secondary battery of the present invention is also expected to be used as industrial batteries such as power tools, drones, and electric bicycles, and further as residential energy storage systems.

[0371] Explanation of reference numerals in the attached figures

[0372] 100 Non-aqueous secondary batteries

[0373] 110 Battery casing

[0374] 120 Battery casing space

[0375] 130 Positive Lead

[0376] 140 Negative Lead Body

[0377] 150 Positive Electrode

[0378] 160 Negative electrode

[0379] 170 separator

Claims

1. A battery pack, characterized in that, It features a non-aqueous secondary battery, which includes: a positive electrode, a negative electrode, and a non-aqueous electrolyte containing an electrolyte salt and a non-aqueous solvent. The battery pack is constructed by connecting one or more modules consisting of two or more non-aqueous secondary batteries connected in series in parallel, or by connecting two or more modules consisting of two or more non-aqueous secondary batteries connected in parallel in series in series. The ratio of the maximum capacity (B) to the minimum capacity (A) of each non-aqueous secondary battery constituting this module is 1.00 < B / A < 2.

00. The maximum capacity (B) and minimum capacity (A) are calculated by subtracting the charging current capacity equivalent to the current SOC from the fully charged current capacity obtained through charging and discharging before the module is assembled, or by taking each non-aqueous secondary battery out of the module and measuring their charging current capacity. Here, SOC refers to the state of charge, and the fully charged current capacity refers to the capacity of the non-aqueous secondary battery when the SOC is 100%. and, This non-aqueous electrolyte contains a redox shuttle that has a reversible redox potential at a potential higher than the positive electrode potential when fully charged. The redox shuttle comprises a compound represented by the following general formula (1). In equation (1), R 1 R 2 R 3 R 4 R 5 and R 6 The substituents shown are independently hydrogen atoms, halogen atoms, aryl groups, alkyl groups having 1 to 4 carbon atoms, fluoro-substituted alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms, wherein two or more of these substituents are alkoxy groups having 1 to 4 carbon atoms or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms. The non-aqueous solvent comprises acetonitrile and chain carbonates. The electrolyte salt comprises an imide salt and LiPF6, and the molar ratio in the non-aqueous electrolyte is LiPF6 < imide salt.

2. The battery pack according to claim 1, wherein, The molecular weight of the redox shuttle is 100-500.

3. The battery pack according to claim 1, wherein, R 1 ~R 6 Two of the substituents shown are tert-butyl or trifluoromethyl and two are alkoxy groups having 1 to 4 carbon atoms or fluorosubstituted alkoxy groups having 1 to 4 carbon atoms.

4. The battery pack according to claim 1, wherein, The compound represented by the general formula (1) comprises 0.1 to 20% by mass relative to the total amount of the non-aqueous electrolyte.

5. The battery pack according to claim 1 or 2, wherein, The capacity of each non-aqueous secondary battery constituting the module is 1 mAh or more and 100 Ah or less, and the ratio of the maximum capacity (B) to the minimum capacity (A) of each non-aqueous secondary battery is 1.05 < B / A < 2.

00.

6. The battery pack according to claim 1, wherein, The non-aqueous solvent also includes cyclic carbonates.

7. The battery pack according to claim 1, wherein, The acetonitrile content is 5 to 95% by volume relative to the total amount of non-aqueous solvents.

8. The battery pack according to claim 1, wherein, Acetonitrile occupies a smaller volume ratio in the non-aqueous solvent than that of the chain carbonate.

9. The battery pack according to claim 1 or 2, wherein, The content of the imide salt is more than 0.5 mol and less than 3 mol relative to 1 L of the non-aqueous solvent.

10. The battery pack according to claim 9, wherein, The imide salt comprises at least one of LiN(SO2F)2 and LiN(SO2CF3)2.

11. The battery pack according to claim 1 or 2, wherein, The non-aqueous electrolyte has an ionic conductivity of 10–50 mS / cm at 25°C.

12. The battery pack according to claim 1 or 2, wherein, The positive electrode contains a positive electrode active material layer with a unit area weight of 15–100 mg / cm³. 2 .

13. The battery pack according to claim 12, wherein, The weight per unit area of ​​the positive electrode active material layer is 26–60 mg / cm³. 2 .

14. The battery pack according to claim 1 or 2, wherein, The positive electrode contains a lithium-containing compound containing Fe.

15. The battery pack according to claim 1 or 2, wherein, The negative electrode contains graphite or at least one element selected from the group consisting of Ti, V, Sn, Cr, Mn, Fe, Co, Ni, Zn, Al, Si and B.

16. The battery pack according to claim 1 or 2, wherein, The non-aqueous electrolyte contains 0.1 to 30% by volume of electrode protection additives relative to the total amount of the non-aqueous solvent.

17. The battery pack according to claim 16, wherein, The electrode protection additive contains one or more cyclic carbonates with unsaturated bonds.

18. A method for manufacturing a battery pack, characterized in that, This is a method for manufacturing a battery pack with a non-aqueous secondary battery, wherein the non-aqueous secondary battery comprises: a positive electrode, a negative electrode, and a non-aqueous electrolyte containing an electrolyte salt and a non-aqueous solvent. The manufacturing method includes the following steps: A laminate formation process, which forms a laminate comprising the positive electrode and the negative electrode; The manufacturing process of the non-aqueous secondary battery involves housing and sealing the laminate and the non-aqueous electrolyte within a battery casing; and The battery pack is constructed by connecting one or more modules consisting of two or more non-aqueous secondary batteries connected in series in parallel, or by connecting two or more modules consisting of two or more non-aqueous secondary batteries connected in parallel in series. The ratio of the maximum capacity (B) to the minimum capacity (A) of each non-aqueous secondary battery constituting the module is 1.00 < B / A < 2.00, and the non-aqueous electrolyte contains a redox shuttle that has a reversible redox potential at a potential higher than the positive electrode potential when fully charged. The maximum capacity (B) and minimum capacity (A) are calculated by subtracting the charging current capacity equivalent to the current SOC from the fully charged current capacity obtained through charging and discharging before the module is assembled, or by taking each non-aqueous secondary battery out of the module and measuring their charging current capacity. Here, SOC refers to the state of charge, and the fully charged current capacity refers to the capacity of the non-aqueous secondary battery when the SOC is 100%. The redox shuttle comprises a compound represented by the following general formula (1). In equation (1), R 1 R 2 R 3 R 4 R 5 and R 6 The substituents shown are independently hydrogen atoms, halogen atoms, aryl groups, alkyl groups having 1 to 4 carbon atoms, fluoro-substituted alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms, wherein two or more of these substituents are alkoxy groups having 1 to 4 carbon atoms or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms. The non-aqueous solvent comprises acetonitrile and chain carbonates. The electrolyte salt comprises an imide salt and LiPF6, and the molar ratio in the non-aqueous electrolyte is LiPF6 < imide salt.

19. The method for manufacturing a battery pack according to claim 18, wherein, The capacity of each non-aqueous secondary battery constituting the module is 1 mAh or more and 100 Ah or less, and the ratio of the initial maximum capacity (B) of each non-aqueous secondary battery to the initial minimum capacity (A) is 1.05 < B / A < 2.

00.

20. The method for manufacturing a battery pack according to claim 18 or 19, wherein, It also includes a charging process, which performs an initial charge on the non-aqueous secondary battery at a rate of 0.001 to 0.3C.

21. The method for manufacturing a battery pack according to claim 18 or 19, wherein, The non-aqueous solvent comprises acetonitrile and chain carbonate in an amount of 5 to 95% by volume relative to the total amount. The redox shuttle comprises a compound represented by the following general formula (1). In equation (1), R 1 R 2 R 3 R 4 R 5 and R 6 The substituents shown are independently hydrogen atoms, halogen atoms, aryl groups, alkyl groups having 1 to 4 carbon atoms, fluoro-substituted alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms, wherein two or more of these substituents are alkoxy groups having 1 to 4 carbon atoms or fluoro-substituted alkoxy groups having 1 to 4 carbon atoms. The compound represented by the general formula (1) comprises 0.1 to 20% by mass relative to the total amount of the non-aqueous electrolyte. The electrolyte salt contains an imide salt and LiPF6, wherein the content of the imide salt is more than 0.5 mol and less than 3 mol per 1 L of the non-aqueous solvent, and the molar ratio in the non-aqueous electrolyte is LiPF6 < imide salt.

22. The method for manufacturing a battery pack according to claim 21, wherein, R 1 ~R 6 Two of the substituents shown are tert-butyl or trifluoromethyl and two are alkoxy groups having 1 to 4 carbon atoms or fluorosubstituted alkoxy groups having 1 to 4 carbon atoms.

23. The method for manufacturing a battery pack according to claim 21, wherein, The non-aqueous solvent also includes cyclic carbonates.

24. The method for manufacturing a battery pack according to claim 21, wherein, The imide salt comprises at least one of LiN(SO2F)2 and LiN(SO2CF3)2.

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