1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene, and use application and production method for same

Abstract

Provided are: 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene which is a new compound; and a use application and a production method for the new compound.　The present invention provides 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene. This new compound can be produced by, for example, reacting 1,1,1,5,5,5-hexafluoro-3-chloro-2-pentene and 2,2,2-trifluoro ethanol in the presence of a base. Further, the new compound is useful as an additive in a nonaqueous electrolytic solution of a secondary battery.

Description

1,1,1,5,5,5-Hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene, its use and production method

[0001] The present invention relates to a novel compound, 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene, and to uses and a method for producing this novel compound.

[0002] Fluoroolefins are used as solvents, cleaning agents, foaming agents, and intermediates for functional materials, and the novel compounds of the present invention are expected to be used for similar purposes. For example, in the examples of Patent Document 1, CF ３ CH=CHOCH ２ CF ３ , C.F. ３ CH=CHOCH ２ CF ２ CF ２ H has been investigated for its self-extinguishing properties, properties as an electrolyte compound, etc. However, the novel compound of the present invention is not known in the art.

[0003] International Publication No. 2021 / 064222

[0004] An object of the present invention is to provide a novel compound, 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene (hereinafter sometimes simply referred to as "3TFEO2HFP"), as well as uses and a production method for this novel compound.

[0005] The present invention provides the following: [1] 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene. [2] 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene according to claim 1, which is represented by the following formula (1): [3] The 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene according to [1], which is (E)-1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene, (Z)-1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene, or a combination thereof. [4] A method for producing 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene, comprising a step of reacting 1,1,1,5,5,5-hexafluoro-3-chloro-2-pentene with 2,2,2-trifluoroethanol in the presence of a base. [5] The method according to [4], wherein the base is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, and ammonium hydroxide. [6] The method according to [4] or [5], wherein the base is in the form of an aqueous solution, and the reaction is carried out in the presence of a phase transfer catalyst. [7] Use of 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene according to any one of [1] to [3] in a non-aqueous electrolyte. [8] The use according to [7], wherein the non-aqueous electrolyte is a non-aqueous electrolyte for a secondary battery. [9] A non-aqueous electrolyte comprising: an electrolyte; the 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene according to any one of [1] to [3]; and a non-aqueous organic solvent.

[10] The non-aqueous electrolyte according to [9], wherein the electrolyte is lithium hexafluorophosphate, and the non-aqueous organic solvent is a carbonate solvent.

[11] A secondary battery containing the nonaqueous electrolyte solution according to [9].

[12] The secondary battery according to

[11] , wherein the secondary battery is a lithium ion secondary battery.

[0006] According to the present invention, a novel compound, 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene, is provided, as well as uses and a method for producing the novel compound. It has been found that this novel compound is particularly useful as an additive for non-aqueous electrolytes, and can be produced using readily available 1,1,1,5,5,5-hexafluoro-3-chloro-2-pentene, 2,2,2-trifluoroethanol, and a base such as sodium hydroxide.

[0007] 1 is a cross-sectional view of a laminate cell used in battery evaluation in Examples 2 and 3. It is a graph showing the change in capacity retention rate in a cycle test carried out in the battery evaluation in Examples.

[0008] [Function] As represented by formula (1), the novel compound of the present invention has a unique chemical structure in which a trifluoromethyl group and two groups (2,2,2-trifluoroethyl group and 2,2,2-trifluoroethoxy group) each having a terminal trifluoromethyl group are bonded to three of the four substitution positions of a C=C double bond. Because the molecular weight is relatively large at 276, the boiling point is 125 to 130°C / atmospheric pressure, and the compound is a liquid at room temperature and normal pressure. Because there are nine fluorine atoms in the molecule, the compound is self-extinguishing, and two of the trifluoromethyl groups extending outward from the molecule are bonded to a rigid C=C double bond via a methylene group (-CH ２Because the C═C double bond is linked via a trifluoromethyl group (-), it has a relatively high degree of freedom, and external attack by a reaction reagent on the C═C double bond is moderately limited. The 2,2,2-trifluoroethoxy group attached to the C═C double bond is affected by the electron-withdrawing property of the terminal trifluoromethyl group, but the presence of a methylene group imparts moderate electron-withdrawing property to the C═C double bond compared to a trifluoromethoxy group. Therefore, the reactivity of the C═C double bond is moderately limited. Based on this chemical structure, the novel compound of the present invention is liquid at room temperature and pressure, self-extinguishing, and can be used in a chemically stable state. After use, it can be recovered as a low-molecular-weight compound by cleavage of the C═C double bond and ether bond. Because of these characteristics, the novel compound of the present invention is considered to be useful as a solvent, cleaning agent, foaming agent, intermediate for functional materials, and the like. Furthermore, as described below in the Examples, the present inventors have newly discovered that the novel compound of the present invention can form a high-quality coating at the positive and negative electrode interfaces of secondary batteries, thereby providing excellent battery characteristics. In general, a non-aqueous organic solvent is used as the electrolyte for secondary batteries, and lithium hexafluorophosphate (LiPF ６ ) is added. The novel compound of the present invention has three trifluoromethyl groups, which gives it a high affinity with fluorine compounds, while its carbon chain basic skeleton gives it a high affinity with non-aqueous organic solvents, allowing it to be uniformly mixed in the electrolyte. Furthermore, the conjugation of the C═C double bond and ether bond present in the center of the molecule allows it to stably exist in an electrically polarized state, resulting in a high affinity with the positive and negative electrode interfaces and a stable existence between these electrodes. Due to these chemical structural features, it is believed to be useful as an additive for the electrolyte of a secondary battery.

[0009] [Method for Producing 3TFEO2HFP] The novel compound of the present invention, 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene, can be produced by reacting 1,1,1,5,5,5-hexafluoro-3-chloro-2-pentene with 2,2,2-trifluoroethanol in the presence of a base.

[0010] The starting materials, 1,1,1,5,5,5-hexafluoro-3-chloro-2-pentene and 2,2,2-trifluoroethanol, are both known substances and can be easily produced by known methods or can be easily obtained as a reagent. Trifluoroethanol may be used in a slight excess amount per mole of 1,1,1,5,5,5-hexafluoro-3-chloro-2-pentene, and is preferably used in a ratio of 1 to 1.5 moles, more preferably 1 to 1.3 moles, and most preferably 1 to 1.2 moles.

[0011] Examples of the base include inorganic bases such as hydroxides such as alkali metal hydroxides (sodium hydroxide, potassium hydroxide, etc.), ammonium hydroxide, and other hydroxides; hydrogen carbonates and carbonates such as alkali metal hydrogen carbonates and carbonates (sodium hydrogen carbonate, sodium carbonate, etc.); and metal hydrides such as alkali metal hydrides (sodium hydride, potassium hydride, etc.); and organic bases such as alkylamines (triethylamine, tetramethylethylenediamine, N,N-diisopropylamine, etc.), 1-azabicyclo[2.2.2]octane, 1,4-diazabicyclo[2.2.2]octane (abbreviation: DABCO), 1,8-diazabicyclo[5.4.0]undec-7-ene (abbreviation: DBU), pyridine, 4-(dimethylamino)pyridine, pyrrolidine, piperidine, and morpholine. Preferred are sodium hydroxide, potassium hydroxide, and ammonium hydroxide, and particularly preferred is sodium hydroxide (caustic soda). The base may be used in excess, preferably in an amount of 1 to 3 moles, more preferably 1 to 2 moles, and most preferably 1 to 1.5 moles, per mole of the starting material 1,1,1,5,5,5-hexafluoro-3-chloro-2-pentene. When the base is used in the form of an aqueous solution, the concentration of the aqueous solution is preferably 5 to 30%, more preferably 5 to 20%, and most preferably 10 to 15%, based on the weight of the entire aqueous solution.

[0012] A phase transfer catalyst can be present in the reaction solution. When the base used in the present invention is in the form of an aqueous solution, the reactive species are present in the aqueous phase. On the other hand, the raw materials 1,1,1,5,5,5-hexafluoro-3-chloro-2-pentene and 2,2,2-trifluoroethanol are lipophilic and therefore present in the oil phase and do not dissolve in the aqueous phase. Therefore, by using a phase transfer catalyst, the active species in the aqueous phase can be transferred to the oil phase, thereby accelerating the reaction. Examples of phase transfer catalysts include quaternary ammonium salts such as tetrabutylammonium bromide and tetrabutylammonium chloride, quaternary phosphonium salts such as tetrabutylphosphonium chloride and tetrabutylphosphonium bromide, and crown ethers such as 12-crown-4, 15-crown-5, and 18-crown-6, but tetrabutylammonium bromide and tetrabutylammonium chloride are preferred, with tetrabutylammonium bromide being particularly preferred. The phase transfer catalyst is used in a proportion of preferably 0.005 to 0.1 mole, more preferably 0.01 to 0.05 mole, most preferably 0.01 to 0.02 mole per mole of the starting material 1,1,1,5,5,5-hexafluoro-3-chloro-2-pentene.

[0013] When a solvent is used, in addition to water, water-miscible solvents such as amides such as dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP), lower alcohols such as methanol and ethanol, ethers such as tetrahydrofuran (THF) and 1,4-dioxane, and acetonitrile can be used. Even when using a water-immiscible organic solvent and water, the reactive species can be present in both the aqueous phase and the oil phase (organic solvent phase) by using the aforementioned phase transfer catalyst. Examples of such organic solvents include ether-based solvents such as diethyl ether, halogenated hydrocarbon-based solvents such as dichloromethane, aromatic hydrocarbon-based solvents such as benzene, toluene, and xylene, and aliphatic hydrocarbon-based solvents such as pentane, hexane, and octane. Preferred examples of the solvent are water, DMF, and acetonitrile.

[0014] The reaction temperature is preferably −40° C. to 120° C., more preferably −20° C. to 60° C., more preferably −10° C. to 40° C., and most preferably 0° C. to 25° C. The reaction pressure may be atmospheric pressure, and a glass reactor can be used.

[0015] [Uses of 3TFEO2HFP] As described above, the novel compound of the present invention is liquid at room temperature and pressure, has self-extinguishing properties, and can be used in a chemically stable state, while having the chemical structural characteristics that allow it to be recovered as a low-molecular-weight compound by cleavage of the C=C double bond and ether bond after use. Due to these characteristics, the novel compound of the present invention is considered to be useful as a solvent, cleaning agent, foaming agent, intermediate for functional materials, etc.

[0016] Furthermore, as will be described later in the Examples, the present inventors have newly discovered that the novel compound of the present invention forms a high-quality coating on the positive and negative electrode interfaces of a secondary battery, thereby providing excellent battery characteristics. When the novel compound of the present invention is used as an additive to an electrolyte solution of a secondary battery, it is preferably added to the electrolyte solution in an amount of preferably 0.005 to 10 wt %, more preferably 0.1 to 7.5 wt %, and most preferably 1 to 5 wt %, when the entire electrolyte solution is taken as 100 wt %.

[0017] Preferred examples of the composition of the electrolyte solution containing the novel compound of the present invention include the following compositions. (Range of Electrolyte Solution Composition) (1) Non-aqueous organic solvent: balance The non-aqueous organic solvent is not particularly limited, and examples thereof include carbonate solvents such as ethylene carbonate and ethyl methyl carbonate, chain carbonate esters, phosphate esters, cyclic ethers, chain ethers, lactone compounds, chain esters, nitrile compounds, amide compounds, and sulfone compounds. Of these organic solvents, carbonate solvents are preferred because they are commonly used as organic solvents for lithium secondary batteries. (2) Electrolyte: preferably 0.1 to 2 mol / L, more preferably 0.15 to 1.8 mol / L, and most preferably 0.3 to 1.2 mol / L relative to the volume of the solvent. The electrolyte is not particularly limited, and examples thereof include lithium hexafluorophosphate (LiPF ６), lithium fluoride (LiBF ４ ), lithium trifluoromethanesulfonate (LiCF ３ SO ３ ), LiBF ３ CF ３ , LiBF ３ C ２ F ５ , LiC ２ F ５ SO ３ , LiC ３ F ７ SO ３ , LiC ４ F ９ SO ３ , LiN(SO ２ F) ２ , LiN(CF ３ SO ２ ) ２ , LiN(C ２ F ５ SO ２ ) ２ , LiN(C ２ F ５ SO ２ ) ２ , LiN(CF ３ SO ２ ) (CF ３ CO), LiN(CF ３ SO ２ ) (C ２ F ５ SO ２ ), LiC(CF ３ SO ２ ) ３ The electrolytes can be used alone or in combination of two or more. Among the fluorine-based electrolytes, LiPF is preferred from the viewpoint of safety and stability of the non-aqueous electrolyte, and improvement of electrical conductivity and cycle characteristics. ６(3) The novel compound of the present invention is preferably added to the electrolyte in an amount of 0.005 to 10 wt %, more preferably 0.1 to 7.5 wt %, and most preferably 1 to 5 wt %, based on 100 wt % of the total electrolyte solution. (4) Other optional additive components (fluoroethyl carbonate (FEC), vinylene carbonate (VC), lithium difluorophosphate, etc.): These are added in small amounts compared to the solvent and electrolyte, and are used as additives expected to improve battery performance, such as by forming a film. These are added to the electrolyte in an amount of 0.005 to 10 wt %, more preferably 0.1 to 7.5 wt %, and most preferably 1 to 5 wt %, based on 100 wt % of the total electrolyte solution.

[0018] [Production Example 1] 89.3 g of 3-chloro-1,1,1,5,5,5-hexafluoro-2-pentene, 50.4 g of 2,2,2-trifluoroethanol, and 1.62 g of tetrabutylammonium bromide were introduced into a 500 mL glass three-neck flask, and 268 g of 12.5% ​​aqueous caustic soda solution was added dropwise over 25 minutes. After stirring for 10 minutes at room temperature (25°C), the production of 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene was confirmed by NMR. After washing with water, the mixture was purified by distillation, and 76.7 g (yield 66%) of 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene with a GC purity of 99% or more was obtained. Analysis of the product revealed that the isomer ratio (E) / (Z) was 30 / 1.

[0019] [Production Example 2] 100 g of 3-chloro-1,1,1,5,5,5-hexafluoro-2-pentene, 47.1 g of 2,2,2-trifluoroethanol, and 1.82 g of tetrabutylammonium bromide were introduced into a 500 mL glass three-neck flask, and 151 g of 12.5% ​​aqueous caustic soda solution was added dropwise. After stirring at room temperature (25°C) for 12 hours, the production of 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene was confirmed by NMR. After washing with water, the product was purified by distillation, and 117 g (yield 90%) of 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene with a GC purity of 99% or more was obtained. Analysis of the product revealed that the isomer ratio (E) / (Z) was 30 / 1. The boiling point of the product (mixture of isomers) was 73-76° C. / 180-190 hPa, 125-130° C. / atmospheric pressure.

[0020] The NMR data and GC-MS data of (E)-1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene are shown below. １ H-NMR (400MHz); δ 3.25 (q, JHF=9.6Hz, 2H), 4.10 (q, JHF=7.2Hz, 2H), 5.00 (q, JHF=7.6Hz, 1H). １９ F-NMR (376MHz); δ -63.9 to -64.1 (m, 3F), -55.0 to -55.1 (m, 3F), -74.2 to -74.3 (m, 3F) GC-MS m / z (%): 276 (CF ３ CH=C(CH ２ CF ３ ) OCH ２ CF ３ ), 207 (CF ３ CH=C(CH ２ ) OCH ２ CF ３ ), 193 (CF ３ CH=COCH ２ CF ３ ), 83 (CH ２ CF ３ ).

[0021] The NMR data and GC-MS data of (Z)-1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene are shown below. １ H-NMR (400MHz); δ3.02(q, J ＨＦ =9.6 Hz, 2H), 4.26(q, J ＨＦ =7.6 Hz, 2H), 5.23(q, J ＨＦ =8.0 Hz, 1H). １９ F-NMR (376MHz); δ-64.8 to -65.0 (m, 3F), -57.5 to -57.6 (m, 3F), -75.1 to -75.2 (m, 3F) GC-MS m / z (%): 276 (CF ３ CH=C(CH ２ CF ３ ) OCH ２ CF ３ ), 207 (CF ３ CH=C(CH ２ ) OCH ２ CF ３ ), 193 (CF ３ CH=COCH ２ CF ３ ), 83 (CH ２ CF ３ ).

[0022] [Battery Evaluation] In order to clarify that 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene, which is the novel compound obtained in the above Production Example and is represented by formula (1), is effective in forming a high-quality coating, an evaluation test was carried out on a nonaqueous electrolyte secondary battery using a nonaqueous electrolyte containing 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene. In addition, in order to compare the additive effect with that of the compound described in the examples of Patent Document 1, a compound similar to that in Patent Document 1 (CF ３ CH=CHOCH ２ CF ３ ) was synthesized and battery evaluation was carried out.

[0023] In this evaluation test, a nonaqueous electrolyte secondary battery of the laminate cell shown in FIG. 1 was fabricated using an electrolyte containing 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene obtained in Production Example 1 or Production Example 2.

[0024] <Fabrication Procedure> [Structure of Battery Used] The cross-sectional structure of the laminate cell used in this evaluation test is shown in Figure 1. In this laminate cell, a positive electrode material 1 is applied onto a positive electrode current collector 2, a positive electrode tab 3 extending from the positive electrode current collector 2 can be electrically connected to wiring from a measuring device with a clip, a negative electrode material 5 is applied onto a negative electrode current collector 6, a negative electrode tab 7 extending from the negative electrode current collector 6 can be electrically connected to wiring from a measuring device with a clip, and a separator 4 is disposed between the positive electrode material 1 and the negative electrode material 5. Each component has a flat rectangular shape, and is arranged in layers in the following order: positive electrode current collector 2, positive electrode material 1, separator 4, negative electrode material 5, and negative electrode current collector 6, and is housed in a laminate exterior 8.

[0025] [Battery Components Used] The positive electrode was a lithium nickel cobalt manganese oxide (NCM111) electrode coated on an aluminum current collector, and the negative electrode was an artificial graphite electrode coated on a nickel current collector. The thickness of the positive electrode material (electrode coating portion) was 53 μm, and the thickness of the negative electrode material was approximately 56 μm. The separator was a polypropylene microporous membrane (manufactured by Celgard; product name "Celgard #2400") cut to 5 cm x 6.5 cm. The laminate exterior was an 11 cm x 20 cm piece folded in half to create the laminate cell shown in Figure 1.

[0026] [Battery Assembly] In the above laminate cell, NCM111 was used for the positive electrode and artificial graphite for the negative electrode, cut to the specified size (positive electrode: 4 cm x 5 cm, negative electrode: 4.5 cm x 5 cm). Tabs for clamping alligator clips were welded to each electrode, and a separator (5 cm x 6.5 cm) was sandwiched between the positive and negative electrodes. The laminate cell was then placed in the cell and dried at 100 ° C. for 1 hour. Then, 0.5 mL of the electrolyte solution containing the compound represented by formula (1) of the present invention synthesized in Preparation Example 1 was poured into an Ar glove box, and the laminate cell was sealed using a vacuum sealer.

[0027] Example 1 A non-aqueous solvent was prepared by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a volume ratio of EC:EMC=3:7, and lithium hexafluorophosphate (LiPF) was used as an electrolyte. ６ The compound represented by formula (1) of the present invention was added in an amount of 1 mol / L to prepare a nonaqueous electrolyte solution, and a nonaqueous electrolyte secondary battery of a laminate cell type shown in FIG. 1 was fabricated.

[0028] [Example 2] A non-aqueous solvent was prepared by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a volume ratio of EC:EMC = 3:7, and lithium hexafluorophosphate (LiPF) was used as an electrolyte. ６ The compound represented by formula (1) of the present invention was added in an amount of 5% by weight to a solution in which the above compound was dissolved at a ratio of 1 mol / L, to prepare a nonaqueous electrolyte solution, and a nonaqueous electrolyte secondary battery of a laminate cell shown in FIG. 1 was fabricated.

[0029] Comparative Example 1: A non-aqueous solvent was prepared by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a volume ratio of EC:EMC=3:7, and lithium hexafluorophosphate (LiPF) was used as an electrolyte. ６ was dissolved at a ratio of 1 mol / L.

[0030] Comparative Example 2: A non-aqueous solvent was prepared by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a volume ratio of EC:EMC=3:7, and lithium hexafluorophosphate (LiPF) was used as an electrolyte. ６ In a solution of 1 mol / L of ３ CH=CHOCH ２ CF ３ A non-aqueous electrolyte solution was prepared by adding 1% by weight of the above to the solution, and a non-aqueous electrolyte secondary battery of the laminate cell type shown in FIG. 1 was fabricated.

[0031] Comparative Example 3: A non-aqueous solvent was prepared by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a volume ratio of EC:EMC=3:7, and lithium hexafluorophosphate (LiPF) was used as an electrolyte. ６ In a solution of 1 mol / L of ３CH=CHOCH ２ CF ３ A non-aqueous electrolyte solution was prepared by adding 5% by weight of the above to the solution, and a non-aqueous electrolyte secondary battery of the laminate cell type shown in FIG. 1 was fabricated.

[0032] [Measurement Method] In order to remove gas generated in the initial stage, each of the nonaqueous electrolyte secondary batteries of Examples 1 and 2 and Comparative Examples 1 to 3 was charged at a constant current of 0.2 C at 60° C. up to 30% of the theoretical capacity, and then stored for 15 hours. (Aging, 1 ｓｔ charging)

[0033] Thereafter, the nonaqueous electrolyte secondary batteries of Examples 1 and 2 and Comparative Examples 1 to 3 that had been aged as described above were placed in an Ar glove box, the edges of the laminated cells were cut, degassing was performed, and the laminated cells were again sealed in a vacuum state using a laminator. (Degassing)

[0034] Next, each of the nonaqueous electrolyte secondary batteries of Examples 1 and 2 and Comparative Examples 1 to 3 was charged at a constant current of 0.2 C at 25° C. up to 4.2 V, and then further charged at a constant voltage with a cut-off current of 0.02 C until the current value reached 1 / 50 of the theoretical capacity of the active material weight, and then discharged at a constant current of 0.2 C down to 2.75 V. (2 ｎｄ , 3 ｒｄ charging / discharging)

[0035] Next, each of the nonaqueous electrolyte secondary batteries of Examples 1 and 2 and Comparative Examples 1 to 3 was charged at a constant current of 1 C at 25° C. until the voltage reached 4.2 V, and then charged at a constant voltage with a cut-off current of 0.1 C until the current value reached 1 / 10 of the theoretical capacity of the active material weight, and then discharged at a constant current of 1 C until the capacity reached 50% of the theoretical capacity. (4 ｔｈ charging / discharging)

[0036] Thereafter, each of the nonaqueous electrolyte secondary batteries of Examples 1 and 2 and Comparative Examples 1 to 3 was charged at a constant current of 1 C at 45° C. until the voltage reached 4.2 V, and then charged at a constant voltage with a cut-off current of 0.1 C until the current value reached 1 / 10 of the theoretical capacity of the active material weight, and then discharged at a constant current of 1 C until the voltage reached 2.75 V. (5 ｔｈ ~Charge / Discharge)

[0037] In addition, every 100 cycles, the battery was charged at a constant current of 0.2 C until the voltage reached 4.2 V, and then charged at a constant voltage with a charge termination current of 0.1 C until the current value reached 1 / 10 of the theoretical capacity of the active material weight, and then discharged at a constant current of 1 C until the voltage reached 2.75 V.

[0038] The first (5) measurement at 45°C and 1C was performed as described above. ｔｈ ) discharge capacity D ５ , x-th discharge capacity D ｘ Based on (x=105, 205), the capacity retention rate (%) after x cycles of each of the nonaqueous electrolyte secondary batteries of Examples 1 and 2 and Comparative Examples 1 to 3 was calculated using the following formula, and the results are shown in Table 1. Capacity retention rate (%)=(D ｘ / D ５ ) x 100

[0039]

[0040] As can be seen from Table 1, Examples 1 and 2 have higher capacity retention rates at the 105th cycle than Comparative Examples 1 to 3, and are therefore superior in cycle characteristics. At the 205th cycle, there was a further difference in the capacity retention rates between the Examples and Comparative Examples, with Example 2 showing the highest capacity retention rate. It can be said that the 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene of the present invention represented by formula (1) forms a high-quality coating at the interface between the positive electrode and the negative electrode, and can provide excellent battery characteristics.

Claims

1. 1,1,1,5,5,5-Hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene.

2. 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene according to claim 1, which is represented by the following formula (1):

3. The 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene of claim 1, which is (E)-1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene, (Z)-1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene, or a combination thereof.

4. A method for producing 1,1,1,5,5,5-hexafluoro-3-chloro-2-pentene, which comprises a step of reacting 1,1,1,5,5,5-hexafluoro-3-chloro-2-pentene with 2,2,2-trifluoroethanol in the presence of a base.

5. The method according to claim 4, wherein the base is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, and ammonium hydroxide.

6. The process of claim 4 or 5, wherein the base is in the form of an aqueous solution and the reaction is carried out in the presence of a phase transfer catalyst.

7. Use of the 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene according to any one of claims 1 to 3 in a non-aqueous electrolyte.

8. The use according to claim 7, wherein the non-aqueous electrolyte is a non-aqueous electrolyte for a secondary battery.

9. A non-aqueous electrolyte solution comprising: an electrolyte; the 1,1,1,5,5,5-hexafluoro-3-(2,2,2-trifluoroethoxy)-2-pentene according to any one of claims 1 to 3; and a non-aqueous organic solvent.

10. The non-aqueous electrolyte according to claim 9, wherein the electrolyte is lithium hexafluorophosphate and the non-aqueous organic solvent is a carbonate solvent.

11. A secondary battery containing the nonaqueous electrolyte solution according to claim 9.

12. The secondary battery according to claim 11, wherein the secondary battery is a lithium ion secondary battery.

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