KR102638391B1 - Method for producing dialkanesulfonyl isosorbide compound, electrolyte additive for lithium secondary battery, electrolyte for lithium secondary battery, and lithium secondary battery - Google Patents

Abstract

The present invention relates to a novel production method of a dialkanesulfonyl isosorbide compound, a lithium secondary battery electrolyte additive consisting of a high-purity dialkanesulfonyl isosorbide compound with a low chlorine concentration prepared by the above production method, and a lithium secondary battery containing the same. Provides electrolyte and lithium secondary batteries.
According to the method for producing dialkanesulfonyl isosorbide compounds of the present invention, the problems of direct reaction between acid and base and long time required in the conventional technology are solved, and high purity dialkanesulfonyl isosorbide compounds with reduced chlorine content are produced. It can be manufactured simply.
According to the electrolyte solution additive for lithium secondary batteries, the electrolyte solution for lithium secondary batteries, and the lithium secondary battery of the present invention, the electrochemical properties of lithium secondary batteries, especially lithium secondary batteries containing a high nickel cathode material, can be improved.

Description

Method for producing dialkanesulfonyl isosorbide compound, electrolyte additive for lithium secondary battery, electrolyte for lithium secondary battery, and lithium secondary battery }

The present invention relates to a novel production method that can produce dialkanesulfonyl isosorbide compounds stably and with high purity.

In addition, the present invention relates to an electrolyte solution additive for lithium secondary batteries made of a dialkanesulfonyl isosorbide compound with reduced chlorine impurities prepared by the above production method, an electrolyte solution for lithium secondary batteries containing the electrolyte solution additive, and lithium containing the electrolyte solution. It is about secondary batteries.

Lithium secondary batteries are largely composed of an anode, a cathode, an electrolyte, and a separator. The anode and cathode generate energy by repeating intercalation and deintercalation of lithium ions, the electrolyte becomes a passage through which lithium ions move, and the separator serves to prevent short circuits within the battery when the anode and cathode meet. Perform. In particular, the positive electrode is closely related to the capacity of the battery, and the negative electrode is closely related to battery performance such as fast charging and discharging.

In the formation process that occurs during the production of a battery, a thin film called SEI (Solid Electrolyte Interphase) is formed on the cathode surface and a thin film called CEI (cathode electrolyte interphase) is formed on the anode surface.

Patent Document 1 discloses a compound having an isosorbide skeleton and a sulfonic acid group as an additive material that is included in the non-aqueous electrolyte solution of a lithium secondary battery and acts to form a film on the electrode surface. In Patent Document 1, the lifespan of a battery manufactured was evaluated using an electrolyte solution containing dimethanesulfonyl isosorbide compound as an additive, but the manufacturing method or purification method of the compound is not presented, and the manufacturing process among the compounds is not provided. There is no awareness of the chlorine contained in it and the problems associated with it.

In the conventional technology for producing dialkanesulfonyl isosorbide compounds, isosobide and alkanesulfonyl chloride are reacted in the presence of a basic catalyst, and purification is performed through crystallization.

In Patent Document 2, 1,4;3,6-dianhydro-D-glucitol 2,5-dimethanesulfonate (i.e., dimethanesulfonyl isosorbide) was synthesized using pyridine as a solvent and base. , the reaction proceeds at room temperature for more than 15 hours, and distillation under reduced pressure is performed to remove pyridine, which is both a solvent and a base. This reaction takes a long time to obtain the product, and there is a risk to workers because basic pyridine and acidic methanesulfonyl chloride react directly during the reaction. Patent Document 2 does not suggest a purification method aimed at high purity after the above reaction.

In Patent Document 3, isosorbide methanesulfonate is prepared by reacting isosorbide and mesyl chloride using anhydrous pyridine as a solvent and base, and the reaction is carried out at room temperature for more than 20 hours. In the subsequent purification step, dichloromethane is used, but the solubility of the product in dichloromethane is low, which may lead to a decrease in yield. Patent Document 3 discloses the use of an isosorbide monoimidazole salt compound as an analgesic, and isosorbide methanesulfonate is presented as an intermediate for synthesizing the isosorbide imidazole salt compound.

In Non-Patent Document 1, isosorbide methanesulfonate is synthesized using pyridine as both a solvent and a base, and the reaction proceeds at room temperature for more than 20 hours. During the reaction, there is a risk to workers as basic pyridine and acidic methanesulfonyl chloride react directly. Non-patent Document 1 does not suggest a purification method aimed at high purity after the above reaction.

Japanese Patent Registration No. 6115122 Publication U.S. Patent Registration No. 4,535,158 China Publication Patent No. 106478653

New J. Chem., 2009, 33, 479-483

The object of the present invention is to provide a new method for producing dialkanesulfonyl isosorbide, which ensures reaction stability and can reduce the chlorine concentration derived from the production process in a simple manner without reducing the final yield of the product. Do this.

The object of the present invention is to provide an electrolyte solution additive made of high-purity dialkanesulfonyl isosorbide that exhibits further improved electrochemical properties compared to conventional electrolyte solution additives made of dialkanesulfonyl isosorbide.

The object of the present invention is to provide an electrolyte solution containing the above electrolyte solution additive, which exhibits further improved electrochemical properties when used in lithium secondary batteries, especially lithium secondary batteries using high nickel cathode materials. Do this.

As a result of various studies, the present inventors have found that dialkanesulfonyl isosorbide compounds produced by conventional methods contain chlorine, which is an impurity derived from chlorine-containing substances used during the production process, and that the concentration of chlorine is set to 50 ppm. It was found that the electrochemical properties of a lithium secondary battery using an electrolyte solution additive made of the dialkanesulfonyl isosorbide were greatly improved by reducing it to the following and using a high-purity dialkanesulfonyl isosorbide, and the present invention was completed. .

In addition, as a result of various studies, the present inventors have found that, in a production method for producing dialkanesulfonyl isosorbide by reacting isosorbide with alkanesulfonyl chloride, a new basic catalyst and an organic solvent that are different from the prior art are used for the reaction. was carried out stably, and furthermore, it was found that chlorine present in the reaction product could be reduced simply and efficiently by using a basic ion exchange resin as a means of reducing chlorine.

The present invention provides the following solutions.

[1] A method for producing dialkanesulfonyl isosorbide compounds,

The dialkanesulfonyl isosorbide compound is represented by the following general formula (1),

A step of reacting isosorbide and an alkanesulfonyl chloride containing an alkyl group of 1 to 3 carbon atoms in an organic solvent in the presence of a basic catalyst, wherein the basic catalyst is triethylamine and the organic solvent is acetonitrile, methyl sulfoxide, dimethylformamide, or tetrahydrofuran. A method comprising step (1).

(In General Formula (1), R ¹ and R ² represent an alkyl group having 1 to 3 carbon atoms)

[2] In paragraph [1] above,

It further comprises a step (2) of removing chlorine by-products in the reaction product by contacting the reaction product obtained in step (1) with a basic ion exchange resin,

Method for producing a dialkanesulfonyl isosorbide compound wherein the chlorine concentration in the dialkanesulfonyl isosorbide compound represented by general formula (1) obtained through step (2) is 50 ppm or less.

[3] An electrolyte solution additive for lithium secondary batteries, produced by the production method of paragraph [1] or [2] above, and consisting of a dialkanesulfonyl isosorbide compound represented by the following general formula (1) and having a chlorine concentration of 50 ppm or less.

(In General Formula (1), R ¹ and R ² represent an alkyl group having 1 to 3 carbon atoms)

[4] Electrolyte solution for lithium secondary batteries containing lithium salt, non-aqueous organic solvent, and electrolyte solution additive for lithium secondary batteries described in paragraph [3] above.

[5] A lithium secondary battery comprising an anode, a cathode, a separator, and an electrolyte,

The positive electrode includes a lithium composite metal oxide having a nickel content of 80 mol% or more among metals excluding lithium as a positive electrode active material,

A lithium secondary battery, wherein the electrolyte is the electrolyte for a lithium secondary battery as described in paragraph [4] above.

According to the method for producing dialkanesulfonyl isosorbide compounds described in [1] to [2] above, the problems of direct reaction between acid and base and long time required in the prior art are solved, and a high-purity dial with reduced chlorine content is produced. Cansulfonyl isosorbide compounds can be easily prepared.

According to the electrolyte solution additive for a lithium secondary battery described in [3], the electrolyte solution for a lithium secondary battery described in [4], and the lithium secondary battery described in [5], the electrochemical properties of a lithium secondary battery can be improved.

[Figure 1] 1H-NMR spectrum image of the material prepared in Example A1

(Method for producing dialkanesulfonyl isosorbide compound)

The dialkanesulfonyl isosorbide compound produced by the production method of the present invention is represented by the following general formula (1).

(In General Formula (1), R ¹ and R ² represent an alkyl group having 1 to 3 carbon atoms)

The method for producing a dialkanesulfonyl isosorbide compound of the present invention is a step of reacting isosobide and an alkanesulfonyl chloride containing an alkyl group of 1 to 3 carbon atoms in an organic solvent in the presence of a basic catalyst, wherein the basic catalyst is triethylamine or N,N-dimethylaniline, and the organic solvent is acetonitrile, dimethyl sulfoxide, dimethylformamide, or tetrahydrofuran.

By using the combination of a basic catalyst and an organic solvent as described above, unlike the prior art that uses pyridine as a basic catalyst and solvent, direct reaction between acid and base can be prevented, thereby ensuring the stability of the reaction.

Among the basic catalysts, triethylamine is particularly preferred in terms of minimizing residual catalyst after completion of the reaction.

Among the above organic solvents, acetonitrile is particularly preferred in terms of ease of removal in the drying step.

During the above reaction, the concentration of isosorbide in the entire reaction solution is preferably 1 to 2 M.

During the above reaction, the concentration of alkanesulfonyl chloride in the entire reaction solution is preferably 2 to 4 M.

During the above reaction, the amount of basic catalyst used in the entire reaction solution is preferably 2 to 4 moles per 1 mole of isosorbide. It is preferable to set the amount of the basic catalyst used to be more than the above lower limit in terms of minimizing residual catalyst after completion of the reaction, and to set the amount of the basic catalyst to be less than the above upper limit is preferable in terms of reaction speed.

The reaction is preferably carried out at 10 to 25°C. Setting the reaction temperature above the above lower limit is preferable in terms of reaction speed, and setting the reaction temperature below the above upper limit is preferable in terms of reaction stability.

The reaction time for the above reaction is preferably 1 to 2 hours. Setting the reaction time above the above lower limit is preferable in terms of reaction conversion rate, and setting the reaction time below the above upper limit is preferable from the perspective of suppressing side reactions of the catalyst.

Meanwhile, alkanesulfonyl chloride reacted with isosorbide is a substance widely applied in general mesylation reactions, but chlorine is desorbed from it to generate hydrochloric acid, and the present inventors believe that the generation of hydrochloric acid is a reaction product. It was recognized that this could be a factor in increasing the chlorine content in water.

Another aspect of the method for producing the dialkanesulfonyl isosorbide compound of the present invention includes the step (2) of contacting the reaction product obtained in step (1) with a basic ion exchange resin to remove chlorine by-products in the reaction product; It further includes. By performing step (2) after step (1), the concentration of chlorine in the reaction product can be reduced to 50 ppm or less.

The basic ion exchange resin used in step (2) includes, but is not limited to, primary amine, secondary amine, tertiary amine, quaternary ammonium, etc., has a basic atomic group, and chlorine in the reaction product. Any material that can exchange ions with anions in the resin can be used without limitation.

The concentration of chlorine by-products can be reduced by adding a predetermined amount of basic ion exchange resin to the reaction product, stirring at room temperature after completion of addition, and separating the used ion exchange resin. At this time, the amount of basic ion exchange resin added is preferably 0.5 to 2 wt% compared to isosorbide. Additionally, the stirring speed after addition of the basic ion exchange resin is preferably set to 150 to 300 rpm. A vacuum filtration filter is preferred as a means for separating the used ion exchange resin.

By using a basic ion exchange resin, chlorine ions that are difficult to remove by general purification methods can be removed simply and efficiently.

The method for producing the dialkanesulfonyl isosorbide compound of the present invention may further include one or more of the following steps in addition to steps (1) and (2) described above.

That is, between step (1) and step (2), a step (1') of filtering insoluble matter after the reaction in step (1) is completed may be included. A vacuum filtration filter is preferred as a means for filtering insoluble matter.

Alternatively, after step (2), a step (3) of removing the chlorine by-product and adding distilled water to the solution to remove the remaining by-product and precipitate dimethanesulfonyl isosorbide may be further included. Residual by-products removed by washing in step (3) include unreacted materials, salts generated in the base catalyst, residual reaction solvent, etc. By going through step (3), high purity dimethanesulfonyl isosorbide can be precipitated while further reducing the concentration of by-products.

Alternatively, after step (3), a step (4) of drying the dimethanesulfonyl isosorbide precipitated in step (3) may be further included. The drying temperature in step (4) is preferably 40 to 60°C, and the drying means is preferably a vacuum dryer.

(Electrolyte additive for lithium secondary batteries)

The electrolyte solution additive for lithium secondary batteries of the present invention consists of a dialkanesulfonyl isosorbide compound represented by the following general formula (1), which is manufactured by the above-described production method and has a chlorine concentration of 50 ppm or less.

(In General Formula (1), R ¹ and R ² represent an alkyl group having 1 to 3 carbon atoms)

The use of dialkanesulfonyl isosorbide compounds as secondary battery electrolyte additives is known, but the present inventors found that when this crude compound is used as a secondary battery electrolyte additive with a high chlorine concentration, acid is generated within the battery. It was found that by causing side reactions such as salt decomposition and SEI damage, it could be the cause of lowering battery characteristics. The electrolyte additive for lithium secondary batteries of the present invention is made of a dialkanesulfonyl isosorbide compound with a chlorine concentration reduced to 50 ppm or less, produced by the novel production method of the present invention, thereby enabling chemical charging and discharging of lithium secondary batteries using the same. Battery characteristics, such as battery life characteristics and room temperature life characteristics, are greatly improved compared to the prior art.

The chlorine concentration can be measured by the KS M 0180 test method for halogens (F, Cl, Br) and sulfur by ion chromatographic detection after oxidative thermal hydrolysis.

(Electrolyte for lithium secondary batteries)

The electrolyte solution for lithium secondary batteries of the present invention includes a lithium salt, a non-aqueous organic solvent, and an electrolyte solution additive for lithium secondary batteries consisting of a dialkanesulfonyl isosorbide compound represented by the general formula (1) with a chlorine concentration of 50 ppm or less. .

The electrolyte solution additive for lithium secondary batteries is preferably contained in an amount of 0.1 to 10 wt%, more preferably contained in an amount of 0.1 to 5 wt%, and especially preferably contained in an amount of 0.1 to 2 wt% in the total electrolyte solution. do. If the content is less than 0.1 wt%, the effect of forming a film on the electrode surface is not sufficient, and if the content is more than 10 wt%, a thick film is formed on the electrode surface, causing a problem of performance deterioration.

As the lithium salt, those commonly used in lithium secondary batteries can be used. Representative examples of lithium salts include lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF ₆ ), It includes, but is not limited to, lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), and lithium borohydride (LiBH ₄ ). Lithium salt can be used by mixing one or two or more known substances.

Examples of the non-aqueous organic solvent include linear carbonates such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, and ethylmethyl carbonate, ethylene carbonate, propylene carbonate, and butylene carbonate. Cyclic carbonate systems such as methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, γ-valerolactone and γ-caprolactone, linear or cyclic ester systems, poly Ketones such as methyl vinyl ketone and cyclohexanone, dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, 3-methyltetrahydrofuran, 1,3 -Linear or cyclic ethers such as dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, 1,4-dioxane, and other known aprotic organic solvents can be used, but are not limited to these. No. Non-aqueous organic solvents can be used one type or in a mixture of two or more types.

(lithium secondary battery)

The lithium secondary battery of the present invention includes a positive electrode, a negative electrode, a separator, and an electrolyte, and the positive electrode includes a lithium composite metal oxide having a nickel content of 80 mol% or more among metals other than lithium as a positive electrode active material, The electrolyte is characterized in that it is the lithium secondary battery electrolyte of the present invention described above.

The lithium composite metal oxide is a high-nickel-based lithium composite metal oxide that necessarily contains nickel as a metal other than lithium, and has a nickel content of 80 mol% or more among metals other than lithium. Lithium secondary batteries using high-nickel-based lithium composite metal oxide as a positive electrode active material have high energy density. The lithium composite metal oxide may be a metal other than lithium and nickel, and may further include one or more of Cr, Fe, Co, Cu, Zr, Al, and Mg. Preferably, the lithium composite metal oxide is NCM-based (containing nickel, cobalt, and manganese), NCMA-based (containing nickel, cobalt, manganese, and aluminum), or NCA (containing nickel, cobalt, and aluminum), and more preferably NCM-based. am.

The lithium secondary battery electrolyte of the present invention, which contains an electrolyte solution additive composed of a dialkanesulfonyl isosorbide compound represented by the general formula (1) with the chlorine concentration reduced to 50 ppm or less, is particularly suitable for using such high nickel-based lithium composite metal oxide. When combined with a positive electrode active material containing the battery, the effect of improving battery characteristics in terms of chemical charge/discharge characteristics and room temperature lifespan characteristics increases. However, the scope of the present invention excludes other lithium composite metal oxides other than high-nickel-based lithium composite metal oxides with a nickel content of 80 mol% or more among metals other than lithium, or cases where other positive electrode active materials are further included. no.

The positive electrode includes a binder and a conductive material in addition to the positive electrode active material. As a binder, various known electrode binder materials such as polyvinylidene fluoride-based, polyolefin-based, polyvinyl alcohol-based, and polyacrylic-based can be used alone or in a mixture of two or more types. As a conductive material, graphite such as natural graphite and artificial graphite; Carbon black such as carbon black, acetylene black, Ketjen black, Denka black, thermal black, etc.; Carbon-based materials such as graphene and graphite; Conductive fibers such as carbon fiber and metal fiber; fluorinated carbon; Metal powders such as aluminum and nickel powder; Other conductive polymers such as zinc oxide, potassium titanate, titanium oxide, and polyphenylene derivatives may be mentioned, but are not limited to these, and materials may be used alone or in a mixture of two or more types. The density of the positive electrode active material layer formed on the positive electrode current collector is preferably 1.5 g/cm ³ or more and 6 g/cm ³ or less.

In the lithium secondary battery of the present invention, the configuration of the negative electrode and separator is not particularly limited.

As the negative electrode active material of the negative electrode, one containing graphite, silicon, or both can be used. As the negative electrode binder, in addition to solvent-based binders such as polyvinylidene fluoride, water-based binders such as SBR (styrene butadiene rubber)/CMC (carboxymethyl cellulose) can also be used.

As a separator, a known separator having appropriate ion permeability, mechanical strength, heat resistance, electrode adhesion, and appropriate shutdown temperature can be used, regardless of the layer structure such as a single layer film, multilayer film, or composite film, regardless of whether it is a composite of organic or inorganic materials, It can be used appropriately.

Below, preferred embodiments are presented to aid understanding of the present invention. The examples below are only illustrative of the present invention and do not limit the present invention, and those skilled in the art may make various changes and modifications to the present embodiments within the scope and spirit of the present invention. It can be done.

[Example A1 and Comparative Examples A1 to A2: Preparation of electrolyte additive consisting of dimethanesulfonyl isosorbide compound]

Example A1

Add 10 g (68.4 mmol) of isosorbide (molecular weight 146.14 g/mol) and 15.7 g (137.0 mmol) of methanesulfonyl chloride (molecular weight 114.56 g/mol) to 50 mL of acetonitrile as an organic solvent at room temperature. added. The temperature of the solution was lowered to 0-10°C, and 13.9 g (137.4 mmol) of triethylamine (molecular weight 101.19 g/mol) was slowly added as a basic catalyst. After completion of addition, the solution was reacted with stirring at room temperature for 1 hour.

After completion of the reaction, the insoluble matter was filtered using a vacuum filtration filter. To prepare a high-purity dimethanesulfonyl isosorbide compound, 20 g of Amberlite®A26, an ion exchange resin, was added to the filtered solution above and stirred at room temperature for 30 minutes to remove chlorine by-products. The solution from which the by-products were removed was filtered through a vacuum filtration filter to remove the ion exchange resin, and then 250 mL of distilled water was added to the solution to remove a small amount of residual by-products and precipitate dimethanesulfonyl isosorbide. This was filtered through a vacuum filtration filter and dried in a vacuum dryer at 60°C for 12 hours. 18 g of high purity dimethanesulfonyl isosorbide as a white solid was obtained (final yield 87%).

The 1H-NMR analysis results of dimethanesulfonyl isosorbide obtained in Example A1 are as follows (FIG. 1).

1H-NMR (400MHz, CD ₃ CN-d ₃ ): δ 3.10 (6H, s, -SH ₃ ), 3.83 (1H, dd, -CH ₂ ), 3.93(2H, m, -CH ₂ ), 4.12 ( 1H, d, -CH ₂ ), 4.65 (1H, m, -CH), 4.87 (1H, m, -CH), 5.05 (2H, m, -CH)

The chlorine concentration in the finally obtained dimethanesulfonyl isosorbide was analyzed by standard analysis method KS M 0180 and is listed in Table 1.

The electrolyte additive consisting of dimethanesulfonyl isosorbide obtained in Example A1 is referred to as electrolyte additive (EA1).

Comparative Example A1

10 g (68.4 mmol) of isosorbide (molecular weight 146.14 g/mol) was added and dissolved in 13.5 mL (167.6 mmol) of pyridine as an organic solvent and basic catalyst at room temperature. The temperature of the solution was lowered to 0°C, and 15.7 g (137.0 mmol) of methanesulfonyl chloride (molecular weight 114.56 g/mol) was added dropwise. After completion of addition, the solution was reacted with stirring at room temperature for 20 hours.

After completion of the reaction, 300 mL of dichloromethane was added, washed with 500 mL of saturated sodium bicarbonate solution, and the organic layer was separated. The organic layer was dried and filtered over anhydrous sodium sulfate, the solvent was concentrated under reduced pressure, water was added, the temperature was raised to 55°C, and the mixture was stirred for 2 hours. Afterwards, it was cooled to room temperature, the white solid was separated and filtered, and the obtained filtrate was washed repeatedly with ethanol. By drying in a vacuum dryer at 60°C for 12 hours, 8 g of dimethanesulfonyl isosorbide as a white solid was obtained (final yield 39%). The chlorine concentration in the finally obtained dimethanesulfonyl isosorbide was analyzed by standard analysis method KS M 0180 and is listed in Table 1. The electrolyte additive consisting of dimethanesulfonyl isosorbide obtained in Comparative Example A1 is referred to as electrolyte additive (CA1).

Comparative Example A2

In the same manner as Comparative Example A1 except that the amount of methanesulfonyl chloride added was 19.6 g (171.1 mmol), 10 g of dimethanesulfonyl isosorbide as a white solid was obtained (final yield 48%). The chlorine concentration in the finally obtained dimethanesulfonyl isosorbide was analyzed by standard analysis method KS M 0180 and is listed in Table 1. The electrolyte additive consisting of dimethanesulfonyl isosorbide obtained in Comparative Example A2 is referred to as electrolyte additive (CA2).

division Cl(ppm) Example A1 Electrolyte additive (EA1) N/D Comparative Example A1 Electrolyte additive (CA1) 198 Comparative Example A2 Electrolyte additive (CA2) 258

[Examples 1 to 2 and Comparative Examples 1 to 3: Preparation of electrolyte and preparation of lithium secondary battery having the electrolyte and high nickel-based positive electrode active material]

(Preparation of electrolyte solution)

In a 25:75 (volume ratio) mixture of EC (ethylene carbonate) and DEC (diethyl carbonate) as a non-aqueous organic solvent, LiPF ₆ as a lithium salt was dissolved at a concentration of 1.15 M, and as an electrolyte solution additive, the electrolyte solution additive (EA1) described above, An electrolyte solution was prepared by adding (CA1) or (CA2) in the amounts shown in Table 2 below.

(Manufacture of anode)

Li[Ni _0.8 Co _0.1 Mn _0.1 ]O ₂ as the positive electrode active material, carbon black as the conductive material, and PVdF as the binder were added and mixed with N-methyl-2-pyrrolidone in a weight ratio of 95:2.5:2.5 to form the positive electrode. A slurry was prepared, applied to both sides of aluminum foil (thickness 15㎛) as a current collector, dried at 110°C for 1 hour, and rolled to prepare a positive electrode.

(Manufacture of cathode)

Graphite as a negative electrode active material, carbon black as a conductive material, and CMC (sodium carboxymethyl cellulose) and SBR (styrene butadiene rubber) as a negative electrode binder are added and mixed in triple distilled water at a weight ratio of 96:1:1.5:1.5 to create a negative electrode slurry. was prepared and applied to both sides of a copper foil (thickness 10㎛) as a current collector, dried at 80°C for 0.5 hours, and rolled to prepare a negative electrode.

(Manufacture of lithium secondary batteries)

An electrode assembly was manufactured by interposing a separator made of polyethylene (PE) between the cathode and anode prepared above, and the electrode assembly was placed in a stainless steel coin cell (CR2032) housing with a diameter of 20 mm and a height of 3.2 mm, and placed within the coin cell. A lithium secondary battery was manufactured by injecting the electrolyte solution prepared above.

The electrolyte solution additives and addition amounts used to prepare the electrolyte solution in Examples 1 to 2 and Comparative Examples 1 to 3 are shown in Table 2 below.

Example Comparative example One 2 One 2 3 electrolyte additive (EA1) (EA1) (CA2) (CA2) - Amount of electrolyte additive added in total weight of electrolyte (wt%) One 10 One 10 -

[Reference Examples 4 to 5: Preparation of an electrolyte using a lithium secondary battery electrolyte additive made of a material other than dimethanesulfonyl isosorbide compound, and preparation of a lithium secondary battery having the electrolyte and a high nickel-based positive electrode active material]

A lithium secondary battery electrolyte and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the type and amount of electrolyte additives were changed as shown in Table 3 below.

Reference example 4 5 electrolyte additive vinylene carbonate fluoroethylene
carbonate Amount of electrolyte additive added in total weight of electrolyte (wt%) One 5

[Reference Example 6: Preparation of a lithium secondary battery electrolyte, and preparation of a lithium secondary battery having the electrolyte and a positive electrode active material other than a high nickel-based positive electrode active material]

The lithium secondary battery of Reference Example 6 was manufactured in the same manner as in Example 1, but using Li[Ni _1/3 Co _1/3 Mn _1/3 ]O ₂ as the positive electrode active material.

[Evaluation of battery characteristics]

For the lithium secondary batteries obtained in the above Examples, Comparative Examples, and Reference Examples, chemical charge/discharge characteristics and room temperature life characteristics were evaluated as follows.

<Evaluation of Mars charging and discharging characteristics>

The manufactured lithium secondary battery was charged and discharged under the conditions below, and the measured formation discharge capacity divided by the formation charge capacity is shown in Table 4 below as ICE (Initial Coulombic Efficiency).

Charging conditions: CC-CV 0.2C rate 4.2V 0.05C CUT-OFF

Discharge conditions: CC 0.2C rate 3.0V CUT-OFF

ICE (Initial Coulombic Efficiency, %) Example 1 88.0 Example 2 83.0 Comparative Example 1 85.5 Comparative Example 2 81.0 Comparative Example 3 79.0 Reference example 4 87.9 Reference example 5 88.1 Reference example 6 88.0

<Evaluation of room temperature lifespan characteristics>

A lithium secondary battery that had undergone chemical charging and discharging was subjected to 350 repeated charge-discharge cycles at 25°C under the following conditions.

Charging conditions: CC-CV 1C rate 4.2V 0.05C CUT-OFF

Discharge conditions: CC 1C rate 3.0V CUT-OFF

The room temperature lifespan characteristics were evaluated using the % value of the discharge capacity at 350 cycles relative to the discharge capacity at 1 cycle as the capacity retention rate (%) at 350 cycles. The results are shown in Table 5 below.

350 cycles of
Capacity maintenance rate (%) Example 1 96.0 Example 2 93.1 Comparative Example 1 88.0 Comparative Example 2 86.2 Comparative Example 3 85.5 Reference example 4 88.1 Reference example 5 95.2 Reference example 6 94.1

The new production method of dialkanesulfonyl isosorbide of the present invention ensures reaction stability and can reduce the chlorine concentration derived from the production process in a simple manner without reducing the final yield of the product, making it useful industrially. It can be.

The electrolyte additive made of high-purity dialkanesulfonyl isosorbide of the present invention is more effective in lithium secondary batteries, especially high nickel positive electrodes, than electrolyte additives made of dialkanesulfonyl isosorbide with high chlorine concentration. The electrochemical properties of lithium secondary batteries using ash are greatly improved, so they can be usefully used industrially.

Claims (5)

A method for producing a dialkanesulfonyl isosorbide compound, comprising:
The dialkanesulfonyl isosorbide compound is represented by the following general formula (1),
A step of reacting isosorbide and an alkanesulfonyl chloride containing an alkyl group of 1 to 3 carbon atoms in an organic solvent in the presence of a basic catalyst, wherein the basic catalyst is triethylamine and the organic solvent is acetonitrile, Methyl sulfoxide, dimethylformamide, or tetrahydrofuranine, step (1) and
A step (2) of removing chlorine by-products in the reaction product by contacting the reaction product obtained in step (1) with a basic ion exchange resin,
A method for producing a dialkanesulfonyl isosorbide compound, wherein the chlorine concentration in the dialkanesulfonyl isosorbide compound represented by general formula (1) obtained through step (2) is 50 ppm or less.

(In General Formula (1), R ¹ and R ² represent an alkyl group having 1 to 3 carbon atoms) A lithium secondary battery comprising an anode, a cathode, a separator, and an electrolyte,
The positive electrode has a positive electrode active material having a nickel content of 80 mol% or more among metals excluding lithium,
The electrolyte solution includes a lithium salt, a non-aqueous organic solvent, and an electrolyte solution additive consisting of a dialkanesulfonyl isosorbide compound represented by the general formula (1) having a chlorine concentration of 50 ppm or less, prepared by the production method of claim 1. doing,
Lithium secondary battery. delete delete delete