KR20240044883A - A compound, non-aqueous electrolyte comprising the same and lithium secondary battery - Google Patents

Abstract

In the present invention, by using the compound represented by Formula 1 as a non-aqueous electrolyte additive, the amount of metal eluted from the electrode can be reduced, side reactions inside the battery that can be caused by the metal eluted from the electrode can be suppressed, and high temperature It relates to a non-aqueous electrolyte that can improve stability and lifespan characteristics and a lithium secondary battery containing the same.

Description

Compound, non-aqueous electrolyte containing the same, and lithium secondary battery {A COMPOUND, NON-AQUEOUS ELECTROLYTE COMPRISING THE SAME AND LITHIUM SECONDARY BATTERY}

The present invention relates to a compound that can provide excellent high-temperature cycle characteristics and high-temperature storage characteristics when applied as an additive to a non-aqueous electrolyte solution, a non-aqueous electrolyte solution containing the same, and a lithium secondary battery.

Lithium secondary batteries are the most popular energy storage device in recent years as they can be miniaturized and lightweight while storing high-density energy. Lithium secondary batteries are applied to products in a variety of fields, from small portable devices such as mobile phones and laptops to large devices such as electric vehicles. Since the environments and conditions in which each product is used are different, stable performance is achieved regardless of the environment and conditions. It is important to implement .

Meanwhile, lithium secondary batteries largely include a positive electrode, a negative electrode, a separator, and an electrolyte solution. The positive electrode is a source of lithium ions. When charging, the lithium ions from the positive electrode move to the negative electrode and are stored. When discharging, the lithium ions stored in the negative electrode emit electrons in the process of moving to the positive electrode, generating electrical energy. The electrolyte serves as a medium for lithium ions to move between the anode and cathode, and includes salts, solvents, and additives. The salt acts as a passage for lithium ions, the solvent dissolves the salt well and helps the lithium ions move, and additives are added to improve specific performance depending on the required characteristics of the lithium secondary battery.

Additives can perform various roles depending on their type, the most representative of which is forming a solid electrolyte interface (SEI) on the electrode surface. Lithium secondary batteries have the problem that the positive electrode active material structurally collapses as charging and discharging progresses, and metal ions eluted from the collapsed positive electrode surface are electrodeposited on the negative electrode, deteriorating the performance of the positive and negative electrodes. In this case, when an additive is included in the electrolyte solution, the additive decomposes during initial charging and discharging to form a film called a solid electrolyte interface (SEI) on the electrode surface, and the formed SEI can be dissolved if it does not interfere with the movement of lithium ions. It can also play a role in improving battery characteristics, storage characteristics, or load characteristics by preventing performance deterioration when charging and discharging cycles are repeated.

Specifically, the SEI film formed during the initial charge and discharge prevents the reaction of lithium ions with the carbon-based negative electrode or other materials during subsequent charge and discharge repetitions, and serves as an ion tunnel that selectively passes only lithium ions between the electrolyte and the negative electrode. will be performed. Due to the ion tunnel effect, the SEI film prevents the organic solvent of the electrolyte solution with a high molecular weight from moving to the carbon-based cathode, thereby preventing the carbon-based cathode structure from collapsing. In other words, since the occurrence of side reactions between lithium ions and the carbon-based negative electrode or other materials is suppressed by the formed SEI film, the amount of lithium ions can be reversibly maintained during subsequent charging and discharging.

In other words, the carbon material of the cathode reacts with the electrolyte during initial charging to form a passivation layer on the surface of the cathode, thereby preventing further decomposition of the electrolyte and maintaining stable charging and discharging. In this case, the passivation layer on the surface of the cathode The amount of charge consumed in formation is an irreversible capacity, which has the characteristic of not reacting reversibly during discharge. For this reason, lithium-ion batteries do not exhibit any further irreversible reactions after the initial charging reaction and are able to maintain a stable life cycle.

However, when lithium ion batteries are stored at high temperatures in a fully charged state (e.g., stored at 60°C after 100% charging at 4.15V or higher), there is a problem in which the SEI film gradually collapses over time. This SEI film collapse exposes the cathode surface, and the exposed cathode surface decomposes while reacting with the carbonate-based solvent in the electrolyte solution, causing continuous side reactions. Moreover, these side reactions continuously generate gas. Gases generated from side reactions increase the internal pressure of the battery regardless of their type, and act as a resistance element to lithium movement, causing expansion of the battery thickness and deterioration of battery performance.

Accordingly, in order to provide a lithium secondary battery that can achieve excellent and stable performance, an additive is required that can form SEI that is stable and does not easily decompose, and that prevents the formed SEI from adversely affecting electrode performance.

J.P. 2019-179638 A J.P. 2018-156761 A

The present invention seeks to provide a compound having a cyclic sulfur oxide structure that can realize excellent cycle characteristics of a lithium secondary battery and achieve improved effects in terms of high temperature stability and gas generation, and a non-aqueous electrolyte solution additive containing the same.

In addition, the present invention seeks to provide a non-aqueous electrolyte solution containing the non-aqueous electrolyte additive and a lithium secondary battery containing the non-aqueous electrolyte solution.

The present invention provides a compound, a non-aqueous electrolyte, and a lithium secondary battery.

(1) The present invention provides a compound represented by the following formula (1).

[Formula 1]

In Formula 1,

L ₁ and L ₂ are each independently directly bonded or a substituted or unsubstituted C ₁ to C ₆ alkylene group,

R ₁ and R ₂ are substituents represented by the following formula (2),

X is any one of the substituents represented by the following formulas 3 to 6,

n is any integer from 1 to 3,

[Formula 2]

In Formula 2,

* is the position binding to L ₁ or L ₂ ,

[Formula 3]

In Formula 3 above,

L ₃ to L ₆ are each independently directly bonded or a substituted or unsubstituted C ₁ to C ₆ alkylene group,

R ₃₁ to R ₃₈ are each independently hydrogen or a substituted or unsubstituted C ₁ to C ₆ alkyl group,

Y ₁ is a direct bond, -O-, or a substituted or unsubstituted C ₁ to C ₆ alkylene group,

* is the position bonding to the oxygen atom of Formula 1,

[Formula 4]

In Formula 4 above,

Y ₂ to Y ₄ are each independently a direct bond, -O-, or a substituted or unsubstituted C ₁ to C ₆ alkylene group,

* is the position bonding to the oxygen atom of Formula 1,

[Formula 5]

In Formula 5 above,

Y ₅ and Y ₆ are a direct bond, -N-, -O-, a substituted or unsubstituted C ₁ to C ₆ alkylene group, a substituted or unsubstituted C ₂ to C ₁₀ alkenylene group, or a substituted or unsubstituted alkenylene group. It is an alkynylene group of C ₂ to C ₁₀ ,

R ₄₁ to R ₄₄ are each independently hydrogen, a substituted or unsubstituted C ₁ to C ₆ alkyl group, or a substituted or unsubstituted C ₂ to C ₆ alkenyl group,

* is the position bonding to the oxygen atom of Formula 1,

[Formula 6]

In Formula 6 above,

L ₇ to L ₁₂ are each independently -O-, a direct bond, or a substituted or unsubstituted C ₁ to C ₆ alkylene group,

Y ₇ is a direct bond, -*, -O(R ₅ ), a substituted or unsubstituted C ₁ to C ₆ alkyl group, or a substituted or unsubstituted C ₁ to C ₆ alkoxy group,

R ₅ is a substituted or unsubstituted C ₂ to C ₆ alkenyl group,

* is the position bonding to the oxygen atom of Formula 1,

m and p are integers of 0 or 1, but when p is 1, Y ₇ is a direct bond, and m is 1.

(2) The present invention provides the compound according to (1) above, wherein L ₁ and L ₂ are methylene groups.

(3) The present invention provides the compound according to (1) or (2) above, wherein Y ₁ is a direct bond, -O-, or a substituted or unsubstituted C ₁ to C ₃ alkylene group.

(4) The present invention provides the compound according to any one of (1) to (3) above, wherein the formula (3) is any one of the substituents represented by the following formulas (3-a) to (3-d).

(5) The present invention according to any one of (1) to (4) above, wherein Y ₂ to Y ₄ are each independently a direct bond, -O-, or substituted or unsubstituted C ₁ to C ₃ alkylene. When Y ₂ and Y ₃ are -O-, Y ₄ is a substituted or unsubstituted C ₁ to C ₃ alkylene group.

(6) The present invention provides the compound according to any one of (1) to (5) above, wherein Formula 4 is any one of the substituents represented by the following Formulas 4-a to 4-f.

(7) The present invention provides the compound according to any one of (1) to (6) above, wherein when Y ₅ is -N- or -O-, Y ₆ is a direct bond.

(8) The present invention provides the compound according to any one of (1) to (7) above, wherein Formula 5 is any one of the substituents represented by Formulas 5-a to 5-j.

(9) The present invention according to any one of (1) to (8) above, wherein L ₇ , L _{8 ,} L ₁₁ and L ₁₂ are each independently directly bonded or substituted or unsubstituted C ₁ to C ₃ alkyl. Provided is a rengyine compound.

(10) The present invention provides the compound according to any one of (1) to (9) above, wherein Formula 6 is any one of the substituents represented by the following Formulas 6-a to 6-i.

(11) The present invention provides the compound according to any one of (1) to (10) above, wherein the compound represented by Formula 1 is a compound represented by the following Formulas 1-a to 1-d.

[Formula 1-a]

[Formula 1-b]

[Formula 1-c]

[Formula 1-d]

(12) The present invention relates to lithium salt; non-aqueous solvent; And it provides a non-aqueous electrolyte solution containing the compound according to any one of claims 1 to 11.

(13) The present invention provides the non-aqueous electrolyte solution according to (12) above, wherein the compound is contained in an amount of 0.01% by weight to 10% by weight based on the total weight of the non-aqueous electrolyte solution.

(14) The present invention provides a lithium secondary battery containing the non-aqueous electrolyte according to (12) above.

The compounds of the present invention can be obtained with good synthetic yields, and the storage stability of the compounds is also good. In addition, the compound of the present invention, when used as an additive in a non-aqueous electrolyte solution, forms a low-resistance yet stable SEI, which can improve the lifespan of the battery and also reduce the amount of gas generated, thereby simultaneously improving stability at high temperatures.

Hereinafter, the present invention will be described in more detail to facilitate understanding of the present invention. At this time, the terms or words used in this specification and claims should not be construed as limited to their usual or dictionary meanings, and the inventor should appropriately define the concept of the term in order to explain his or her invention in the best way. It must be interpreted with meaning and concept consistent with the technical idea of the present invention based on the principle that it can be done.

The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

In this specification, terms such as “comprise,” “comprise,” or “have” are intended to designate the presence of implemented features, numbers, steps, components, or a combination thereof, and are intended to indicate the presence of one or more other features or It should be understood that this does not exclude in advance the possibility of the presence or addition of numbers, steps, components, or combinations thereof.

As used herein, the term "substituted or unsubstituted" refers to one selected from deuterium, halogen group, hydroxy group, amino group, thiol group, nitro group, nitrile group, silyl group, and straight or branched chain C ₁ -C ₆ alkoxy group. It means that it is substituted with the above substituents or does not have any substituents.

Compound represented by formula 1

The present invention provides a compound represented by the following formula (1).

Compound represented by Formula 1:

[Formula 1]

In Formula 1,

L ₁ and L ₂ are each independently directly bonded or a substituted or unsubstituted C ₁ to C ₆ alkylene group,

R ₁ and R ₂ are substituents represented by the following formula (2),

X is any one of the substituents represented by the following formulas 3 to 6,

n is any integer from 1 to 3,

[Formula 2]

In Formula 2,

* is the position binding to L ₁ or L ₂ ,

[Formula 3]

In Formula 3 above,

L ₃ to L ₆ are each independently directly bonded or a substituted or unsubstituted C ₁ to C ₆ alkylene group,

R ₃₁ to R ₃₈ are each independently hydrogen or a substituted or unsubstituted C ₁ to C ₆ alkyl group,

Y ₁ is a direct bond, -O-, or a substituted or unsubstituted C ₁ to C ₆ alkylene group,

* is the position bonding to the oxygen atom of Formula 1,

[Formula 4]

In Formula 4 above,

Y ₂ to Y ₄ are each independently a direct bond, -O-, or a substituted or unsubstituted C ₁ to C ₆ alkylene group,

* is the position bonding to the oxygen atom of Formula 1,

[Formula 5]

In Formula 5 above,

Y ₅ and Y ₆ are a direct bond, -N-, -O-, a substituted or unsubstituted C ₁ to C ₆ alkylene group, a substituted or unsubstituted C ₂ to C ₁₀ alkenylene group, or a substituted or unsubstituted alkenylene group. It is an alkynylene group of C ₂ to C ₁₀ ,

R ₄₁ to R ₄₄ are each independently hydrogen, a substituted or unsubstituted C ₁ to C ₆ alkyl group, or a substituted or unsubstituted C ₂ to C ₆ alkenyl group,

* is the position bonding to the oxygen atom of Formula 1,

[Formula 6]

In Formula 6 above,

L ₇ to L ₁₂ are each independently -O-, a direct bond, or a substituted or unsubstituted C ₁ to C ₆ alkylene group,

Y ₇ is a direct bond, -*, -O(R ₅ ), a substituted or unsubstituted C ₁ to C ₆ alkyl group, or a substituted or unsubstituted C ₁ to C ₆ alkoxy group,

R ₅ is a substituted or unsubstituted C ₂ to C ₆ alkenyl group,

* is the position bonding to the oxygen atom of Formula 1,

m and p are integers of 0 or 1, but when p is 1, Y ₇ is a direct bond, and m is 1.

The compound represented by the formula (1) provided by the present invention includes a sulfur oxide substituent having a cyclic structure at both ends, and at the same time, it is characterized by comprising a central portion connecting the cyclic sulfur oxide substituent groups located at both ends. , by adopting this chemical structure, it is possible to induce stable formation of anions in the non-aqueous electrolyte when applied as an additive to the non-aqueous electrolyte, and further to form a stable SEI layer. Specifically, the compounds represented by Formula 1 can efficiently induce film formation by containing two or more SO _x (2≤x≤4) functional groups in one molecule. Specifically, the compound represented by Formula 1 is reduced faster than the non-aqueous solvent in the electrolyte during charging and discharging, and can form a solid film containing LiSOx (2≤x≤4) before side reactions occur, thereby increasing the interfacial resistance. In addition to minimizing the increase, side reactions between the electrode and the electrolyte can be suppressed by preventing the electrode surface from being exposed. Subsequently, the elution of transition metals from the positive electrode due to film collapse can be effectively controlled, and a lithium secondary battery can be implemented that has excellent high-temperature storage characteristics and high-temperature cycling characteristics while preventing battery swelling.

In addition, the compound represented by Formula 1 is a cyclic sulfur oxide derivative compound that has few problems due to toxicity. When the compound is included in a non-aqueous electrolyte solution, a thin and stable SEI layer is formed, resulting in lithium having excellent high-temperature storage characteristics and high-temperature cycling characteristics. A secondary battery can be provided. Meanwhile, in the case of 1,3-propane sultone (PS), a conventional additive, use is limited due to toxicity, and it is difficult to develop a synthesis method to introduce a functional group, whereas the compound represented by Formula 1 of the present invention has a positive Since it contains a cyclic sulfur oxide structure at the terminal and has a structure in which the 2nd or 3rd carbon positions of the cyclic sulfur oxide structure located at both ends are substituted and connected to each other through a linkage, 1,3-propane sultone Unlike , it has low toxicity and is relatively easy to synthesize, so it can achieve the effect of reducing process costs. In addition, the compound represented by Formula 1 of the present invention has better storage stability than ethylene sulfate, known as a conventional electrolyte additive, and can reduce various side reactions and gas generation caused by using ethylene sulfate.

On the other hand, the compound represented by Formula 1 has a reduction potential of 0.5 eV or more, which is higher than that of non-aqueous solvents, so it can be decomposed first under cell driving conditions to form a solid film, and the reduction potential is calculated using the Gaussian 09 program using the DFT calculation method. It can be measured using the package (Gaussian 09 Revision C.01, Gaussian Inc., Wallingford, CT, 2009) using the method below.

1) Calculate the stable structural energy of the compound in the pre-reduced state (E _neut ) and the stable structural energy of the compound in the reduced state (E _red ).

2) E _neut -E _red -1.45eV is defined as the reduction stability value.

3) At this time, the structural stability calculation is performed by applying the PCM (Polarizable Continuum Model) method.

According to one embodiment of the present invention, R ₁ and R ₂ may each independently be a substituent represented by the following formula (2).

[Formula 2]

In Formula 2, * is a position that binds to L ₁ or L ₂ .

When the substituent of Formula 2 is substituted for R ₁ and R ₂ of Formula 1, the overall structural stability of the compound is excellent, and it can smoothly perform the function as an additive for a non-aqueous electrolyte solution. In the substituent structure of Formula 2, “*” is a position connected to L1 and L2 of Formula 1, and can be connected to L1 and L2 of Formula 1 at the 3rd (gamma) carbon position of the substituent structure of Formula 2, and In this case, it may be desirable in terms of structural stability and ease of synthesis.

In addition, by being connected to the 3 (gamma) position of the compound structure of Formula 2, there is an advantage in reducing the toxicity of the material. Specifically, 1,3-propane sultone (PS), a previously used additive, is carcinogenic and has acute toxicity through oral and transdermal routes, so there were restrictions on the use of this additive. Looking at the mechanism by which the toxicity of PS is expressed, when the PS exists together with one or more nucleophiles that can be selected from the group consisting of H ₂ O, Alcohol, Phenol, Thiol, and Amine, the PS The carbon at position 3 of the ring-shaped structure undergoes a ring-opening reaction to form 3-hydroxy-1-Propanesulfonate, the conjugate base of the highly acidic 3-hydroxy-1-Propanesulfonic Acid (HPSA). In addition, since the HPSA is reactive with DNA, it has been confirmed to have strong genotoxicity and the possibility of carcinogenesis. Therefore, since the 3rd position of the cyclic structure of 1,3-propane sultone (PS) is sensitive to nucleophilic attack, a substituent is added to the 3rd position, such as the compound represented by Formula 2 of the present invention. By binding, the reactivity due to the nucleophilic attack can be drastically reduced, thereby reducing toxicity.

In the compound represented by Formula 1, L ₁ and L ₂ may each independently be a direct bond, a methylene group, or an ethylene group, and specifically, a methylene group. When L ₁ and L ₂ are methylene groups, synthesis of the compound is easy and decomposition of the compound after synthesis can be suppressed.

According to one embodiment of the present invention, in Formula 1, “X” is any one of the substituents represented by Formulas 3 to 6, and the You can. The connecting portions represented by Formulas 3 to 6 can connect the cyclic sulfur oxide to both ends by removing the halogen element and combining the oxygen atom at the same time during the synthesis of the cyclic sulfur oxide. In addition, the compound represented by Formula 1 includes a connecting portion represented by Formulas 3 to 6, so that it can scavenge active oxygen and form a stronger SEI than before, so it has a stronger structure than existing PS. Stability and ease of synthesis can be significantly improved.

According to one embodiment of the present invention, in Formula 3, Y ₁ may be a direct bond, -O-, or a substituted or unsubstituted alkylene group of C ₁ to C ₃ . Additionally, Formula 3 may be any one of the substituents represented by Formulas 3-a to 3-d below. In addition, the substituent represented by Formula 3 includes a silicon (Si) atom, thereby causing an inductive effect due to oxygen partially generated on the surface of the cathode, creating an environment in which an SEI layer can be well formed, and oxidation By capturing the anions generated as by-products of the reduction reaction, side reactions can be suppressed and contributing to increased structural stability.

According to one embodiment of the present invention, in Formula 4, Y ₂ to Y ₄ are each independently a direct bond, -O-, or a substituted or unsubstituted C ₁ to C ₃ alkylene group, wherein Y ₂ and When Y ₃ is -O-, Y ₄ may be a substituted or unsubstituted alkylene group of C ₁ to C ₃ , and Formula 4 may be any one of the substituents represented by the following Formulas 4-a to 4-f. You can. In addition, the substituent represented by Formula 4 can contribute to increasing battery stability by introducing a large amount of sulfonate into the molecule, thereby enabling the formation of a strong SEI layer.

According to one embodiment of the present invention, in Formula 5, when Y ₅ is -N- or -O-, Y ₆ may be a direct bond. Additionally, Formula 5 may be any one of the substituents represented by Formulas 5-a to 5-j below. In addition, the compound represented by Formula 5 can play a role in suppressing radical anions that reduce the electrolyte solution by introducing many esters into the molecule, and can increase the stability of the battery by enabling the formation of a solid SEI layer. .

According to one embodiment of the present invention, in Formula 6, L ₇ , L _{8 ,} L ₁₁ and L ₁₂ may each independently be directly bonded or a substituted or unsubstituted C ₁ to C ₃ alkylene group. Additionally, Formula 6 may be any one of the substituents represented by Formulas 6-a to 6-i below.

The substituent represented by Formula 6 may contain a vinyl group. In this case, a free radical polymerization reaction may occur through the vinyl group, forming a film and reducing decomposition of the electrolyte.

In addition, the substituent represented by Formula 6 may include a structure in which a phosphorus atom and an oxygen atom are connected, and the structure generates gas and causes the battery to swell due to decomposition of a non-aqueous solvent, for example, a carbonate solvent, during battery operation. It can play a role in suppressing the swelling phenomenon.

According to one embodiment of the present invention, the compound represented by Formula 1 may be a compound represented by the following Formulas 1-a to 1-d.

[Formula 1-a]

[Formula 1-b]

[Formula 1-c]

[Formula 1-d]

When the compound represented by Formula 1 has the structure described above as preferable, it has the advantage of being able to form a stable SEI layer with low resistance even with a small amount compared to conventionally used additives.

non-aqueous electrolyte

(1) Non-aqueous electrolyte additive

The present invention provides a non-aqueous electrolyte additive containing the compounds described above. The non-aqueous electrolyte solution additive of the present invention may include one or two or more types of compounds represented by Formula 1 described above, and in addition to the compounds represented by Formula 1, it may also include other additives used as additives for non-aqueous electrolyte solutions. .

The present invention provides a non-aqueous electrolyte solution containing the non-aqueous electrolyte additive, a lithium salt, and a non-aqueous solvent. The non-aqueous electrolyte additive is as described above, and the non-aqueous electrolyte additive is 0.01% by weight to 5% by weight, preferably 0.1% by weight to 3% by weight, particularly preferably 0.5% by weight, based on the total weight of the nonaqueous electrolyte solution. It may be included in 2 to 2% by weight. When the additive is included within the above-mentioned range, performance degradation due to side reactions can be suppressed as much as possible, while improvement in discharge stability and charging and discharging efficiency can be maximized.

(2) Non-aqueous solvent

The non-aqueous electrolyte solution of the present invention includes a non-aqueous solvent for dissolving the lithium salt and additives. Specifically, the non-aqueous solvent may be one or more selected from the group consisting of cyclic carbonate-based organic solvents, linear carbonate-based organic solvents, cyclic ester-based organic solvents, and linear ester-based organic solvents. In particular, cyclic carbonate-based organic solvents may be used. A solvent, a linear carbonate-based organic solvent, or a mixed organic solvent thereof may be used.

The cyclic carbonate-based organic solvent is a high-viscosity organic solvent that has a high dielectric constant and can easily dissociate lithium salts in the electrolyte. Specific examples include ethylene carbonate (EC), propylene carbonate (PC), and 1,2-butylene. It may contain at least one organic solvent selected from the group consisting of carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate, and among these, ethylene carbonate. may include.

The linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and representative examples include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, and ethylmethyl carbonate (EMC). , at least one organic solvent selected from the group consisting of methylpropyl carbonate and ethylpropyl carbonate may be used, and may specifically include ethylmethyl carbonate (EMC).

In addition to the cyclic carbonate-based organic solvent and/or linear carbonate-based organic solvent, at least one ester-based organic solvent selected from the group consisting of linear ester-based organic solvent and cyclic ester-based organic solvent is further included to further increase ionic conductivity. You can also do it.

Specific examples of such linear ester organic solvent include at least one organic solvent selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate. I can hear it.

In addition, the cyclic ester organic solvent includes at least one organic solvent selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, α-valerolactone, and ε-caprolactone. You can.

In addition to the organic solvents described above, organic solvents commonly used in non-aqueous electrolytes for lithium secondary batteries can be added and used without limitation, if necessary. For example, it may further include at least one organic solvent selected from the group consisting of an ether-based organic solvent, an amide-based organic solvent, and a nitrile-based organic solvent.

(3) Lithium salt

The non-aqueous electrolyte solution of the present invention contains lithium salt. The lithium salt is configured to provide lithium ions in the electrolyte solution, and can be used without particular restrictions as long as it is typically used in the non-aqueous electrolyte solution of lithium secondary batteries.

For example, it includes Li ⁺ as a cation, and its counter ions include F ^- , Cl ^- , Br ^- , I ^- , NO ₃ ^- , N(CN) ₂ ^- , BF ₄ ^- , ClO ₄ ^- , B ₁₀ Cl ₁₀ ^- , AlCl ₄ ^- , AlO ₄ ^- , PF ₆ ^- , CF ₃ SO ₃ ^- , CH ₃ CO ₂ ^- , CF ₃ CO ₂ ^- , AsF ₆ ^- , SbF ₆ ^- , CH ₃ SO ₃ ^- , (CF ₃ CF ₂ SO ₂ ) ₂ N ^- , (CF ₃ SO ₂ ) ₂ N ^- , (FSO ₂ ) ₂ N ^- , BF ₂ C ₂ O ₄ ^- , BC ₄ O ₈ ^- , PF ₄ C ₂ O ₄ ^- , PF ₂ C ₄ O ₈ ^- , (CF ₃ ) ₂ PF ₄ ^- , (CF ₃ ) ₃ PF ₃ ^- , (CF ₃ ) ₄ PF ₂ ^- , (CF ₃ ) ₅ PF ^- , (CF ₃ ) ₆ P ^- , C ₄ F ₉ SO ₃ ^- , CF ₃ CF ₂ SO ₃ ^- , CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , CF ₃ (CF ₂ ) ₇ SO ^3- and SCN ^- A lithium salt containing one or more selected from the group consisting of can be used.

More specifically, the lithium salt is LiCl, LiBr, LiI, LiBF ₄ , LiClO ₄ , LiB ₁₀ Cl ₁₀ , LiAlCl ₄ , LiAlO ₄ , LiPF ₆ , LiCF ₃ SO ₃ , LiCH ₃ CO ₂ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiCH ₃ SO ₃ , LiFSI (Lithium bis(fluorosulfonyl)imide, LiN(SO ₂ F) ₂ ), LiBETI (lithium bisperfluoroethanesulfonimide, LiN(SO ₂ CF ₂ CF ₃ ) ₂ and LiTFSI (lithium (bis) It may include one or more selected from the group consisting of trifluoromethanesulfonimide, LiN(SO ₂ CF ₃ ) ₂ ).

The concentration of lithium salt in the non-aqueous electrolyte solution can be appropriately adjusted depending on the purpose within a generally acceptable range, for example, it may be 0.5 M to 5.0 M, specifically 0.8 M to 4.0 M or 1.0 M to 3.0 M. there is. If the concentration of lithium salt is too low, the mobility of lithium ions may decrease, which may reduce the output or cycle characteristics of the lithium secondary battery. If the concentration of lithium salt is too high, the viscosity of the non-aqueous electrolyte may increase and the impregnability of the electrolyte may decrease. there is.

(4) Other electrolyte additives

The non-aqueous electrolyte of the present invention is necessary to prevent the non-aqueous electrolyte from decomposing in a high-power environment and causing cathode collapse, or to further improve low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention, and battery expansion suppression at high temperatures. Accordingly, additives for SEI formation may be additionally included in the non-aqueous electrolyte solution.

Representative examples of such additives for forming SEI include cyclic carbonate-based compounds, halogen-substituted carbonate-based compounds, sultone-based compounds, sulfate-based compounds, phosphate-based compounds, borate-based compounds, decannitrile, and 1,4-dicyano-2-butene. In addition, it may include at least one additive for forming an SEI film selected from the group consisting of nitrile-based compounds, benzene-based compounds, amine-based compounds, silane-based compounds, and lithium salt-based compounds.

The cyclic carbonate-based compound may include vinylene carbonate (VC) or vinylethylene carbonate, and may be included in an amount of 3% by weight or less based on the total weight of the non-aqueous electrolyte solution. If the content of the cyclic carbonate-based compound in the electrolyte exceeds 3% by weight, cell swelling inhibition performance may be deteriorated.

The halogen-substituted carbonate-based compound may include fluoroethylene carbonate (FEC), which may be included in an amount of 5% by weight or less based on the total weight of the electrolyte. If the content of the halogen-substituted carbonate-based compound in the electrolyte exceeds 5% by weight, cell swelling performance may be deteriorated.

The sultone-based compounds include 1,3-propane sultone (PS), 1,4-butane sultone, ethenesultone, 1,3-propene sultone (PRS), 1,4-butene sultone, and 1-methyl-1,3 -At least one compound selected from the group consisting of propene sultone.

The sultone-based compound may be included in an amount of 0.3% by weight to 5% by weight, specifically 1% by weight to 5% by weight, based on the total weight of the non-aqueous electrolyte solution. If the content of the sultone-based compound in the electrolyte exceeds 5% by weight, an excessively thick film may be formed on the electrode surface, which may cause increased resistance and deterioration of output, and the resistance due to excessive additives in the electrolyte may increase, reducing the output characteristics. It may deteriorate.

The sulfate-based compound may include ethylene sulfate (Esa), trimethylene sulfate (TMS), or methyl trimethylene sulfate (MTMS), and is contained at 5% by weight based on the total weight of the electrolyte. It may be included below.

The phosphate-based compounds include lithium difluoro(bisoxalato)phosphate, lithium difluorophosphate, tetramethyl trimethyl silyl phosphate, trimethyl silyl phosphite, tris(2,2,2-trifluoroethyl)phosphate, and tris. One or more compounds selected from the group consisting of (trifluoroethyl) phosphite may be included, and may be included in an amount of 5% by weight or less based on the total weight of the electrolyte.

The borate-based compound may include tetraphenyl borate and lithium oxalyldifluoroborate, and may be included in an amount of 5% by weight or less based on the total weight of the electrolyte.

The nitrile-based compounds are nitrile-based compounds other than decannitrile (DN) and 1,4-dicyano-2-butene (DCB), and representative examples thereof include succinonitrile, adiponitrile, acetonitrile, propionitrile, Butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile , phenylacetonitrile, 2-fluorophenylacetonitrile, and at least one compound selected from the group consisting of 4-fluorophenylacetonitrile and 1,3,6-hexanetricarbonitrile.

The nitrile-based compound may be 5% by weight to 8% by weight, specifically 6% by weight to 8% by weight, based on the total weight of the non-aqueous electrolyte solution. If the content of the nitrile-based compound in the electrolyte exceeds 8% by weight, resistance increases due to an increase in the film formed on the electrode surface, and battery performance may deteriorate.

The benzene-based compound may include fluorobenzene, the amine-based compound may include triethanolamine or ethylene diamine, and the silane-based compound may include tetravinylsilane.

The lithium salt-based compound is a compound different from the lithium salt contained in the non-aqueous electrolyte solution, and may include one or more compounds selected from the group consisting of LiPO2F2, LiODFB, LiBOB (lithium bisoxalate borate (LiB(C2O4)2), and LiBF4). and may be included in an amount of 5% by weight or less based on the total weight of the electrolyte.

Among these additives for forming SEI, when vinylene carbonate, vinylethylene carbonate, or succino nitrile is additionally included, a more robust SEI film can be formed on the surface of the cathode during the initial activation process of the secondary battery.

When LiBF4 is included, the high-temperature stability of the secondary battery can be improved by suppressing the generation of gas that may be generated due to decomposition of the electrolyte at high temperatures.

Meanwhile, the additives for forming SEI may be used in combination of two or more types, and may be included in an amount of 0.1% by weight to 50% by weight, specifically 0.01% by weight to 10% by weight, based on the total weight of the non-aqueous electrolyte. It may be 0.05% by weight to 5% by weight. If the content of the SEI-forming additive is less than 0.01% by weight, the effect of improving the low-temperature output and high-temperature storage characteristics and high-temperature lifespan characteristics of the battery is minimal, and if the content of the SEI-forming additive exceeds 50% by weight, the battery's There is a possibility that excessive side reactions within the electrolyte may occur during charging and discharging. In particular, when the additives for forming the SEI film are added in excessive amounts, they may not be sufficiently decomposed at high temperatures and may remain unreacted or precipitated in the electrolyte solution at room temperature. As a result, side reactions that reduce the lifespan or resistance characteristics of the secondary battery may occur.

Lithium secondary battery

In another embodiment of the present invention, a lithium secondary battery containing the non-aqueous electrolyte solution of the present invention is provided.

The lithium secondary battery provided by the present invention can be manufactured by forming an electrode assembly in which a positive electrode, a negative electrode, and a separator are sequentially stacked between the positive electrode and the negative electrode, storing it in a battery case, and then adding the non-aqueous electrolyte of the present invention.

The positive electrode, negative electrode, and separator included in the lithium secondary battery of the present invention can be manufactured and applied according to conventional methods known in the art, as will be specifically described later.

(1) anode

The positive electrode can be manufactured by coating a positive electrode slurry containing a positive electrode active material, binder, conductive material, and solvent on a positive electrode current collector, followed by drying and rolling.

The positive electrode current collector may be conductive without causing chemical changes in the battery, and may be, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or carbon, nickel, or carbon on the surface of aluminum or stainless steel. Those surface treated with titanium, silver, etc. can be used.

The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and may specifically include a lithium composite metal oxide containing lithium and one or more metals such as cobalt, manganese, nickel, or aluminum. there is.

More specifically, the lithium composite metal oxide is lithium-manganese-based oxide (for example, LiMnO ₂ , LiMn ₂ O ₄ , etc.), lithium-cobalt-based oxide (for example, LiCoO ₂ , etc.), lithium-nickel-based oxide. (For example, LiNiO ₂ , etc.), lithium-nickel-manganese oxide (For example, LiNi _1-Y Mn _Y O ₂ (0<Y<1), LiMn _2-z Ni _z O ₄ (0＜Z <2), lithium-nickel-cobalt-based oxide (for example, LiNi _1-Y1 Co _Y1 O ₂ (0<Y1<1), lithium-manganese-cobalt-based oxide (for example, LiCo _1-Y2 Mn _Y2 O ₂ (0<Y2<1), LiMn _2-z1 Co _z1 O ₄ (0＜Z1＜2), lithium-nickel-manganese-cobalt oxide (for example, Li(Ni _p Co _q Mn _r1 )O ₂ (0＜p＜1, 0＜q＜1, 0＜r1＜1, p+q+r1=1) or Li(Ni _p1 Co _q1 Mn _r2 )O ₄ (0＜p1＜2, 0＜q1 <2, 0<r2<2, p1+q1+r2=2), or lithium-nickel-cobalt-transition metal (M) oxide (for example, Li(Ni _p2 Co _q2 Mn _r3 M _s2 )O ₂ ( M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg and Mo, and p2, q2, r3 and s2 are each independent atomic fraction of elements, 0 < p2 < 1, 0 < q2 <1, 0<r3<1, 0<s2<1, p2+q2+r3+s2=1), etc., and any one or two or more of these compounds may be included. Among these, the battery cycle In that the properties and stability can be improved, the lithium composite metal oxide is LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , lithium nickel manganese cobalt oxide (for example, Li(Ni _0.6 Mn _0.2 Co _0.2 )O ₂ , Li(Ni _0.5 It may be Mn _0.3 Co _0.2 )O ₂ , or Li(Ni _0.8 Mn _0.1 Co _0.1 )O ₂ etc.), or lithium nickel cobalt aluminum oxide (for example, Li(Ni _0.8 Co _0.15 Al _0.05 )O ₂ etc.). Considering the remarkable improvement effect due to control of the type and content ratio of the constituent elements forming the lithium composite metal oxide, the lithium composite metal oxide is Li(Ni _0.6 Mn _0.2 Co _0.2 )O ₂ , Li(Ni _0.5 Mn _0.3 It may be Co _0.2 )O ₂ , Li(Ni _0.7 Mn _0.15 Co _0.15 )O ₂ or Li(Ni _0.8 Mn _0.1 Co _0.1 )O ₂ , and any one or a mixture of two or more of these may be used.

The positive electrode active material may be included in an amount of 80% by weight or more, 90% by weight or more, 99% by weight or less, and 95% by weight or less based on the total weight of solids in the positive electrode slurry. At this time, if the content of the positive electrode active material is 80% by weight or less, the energy density may be lowered and the capacity may be reduced.

The binder is a component that assists in the bonding of the active material and the conductive material and the bonding to the current collector, and is usually added in an amount of 1 to 30% by weight based on the total weight of solids in the positive electrode slurry. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, Examples include polyethylene, polypropylene, ethylene-propylene-diene terpolymer, styrene-butadiene rubber, fluorine rubber, and various copolymers.

In addition, the conductive material is a material that provides conductivity without causing chemical changes in the battery, and may be added in an amount of 1 to 20% by weight based on the total weight of solids in the positive electrode slurry.

Representative examples of such conductive materials include carbon powders such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; Graphite powder such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; Conductive fibers such as carbon fiber and metal fiber; Conductive powders such as fluorinated carbon powder, aluminum powder, and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

Additionally, the solvent may include an organic solvent such as N-methyl-2-pyrrolidone (NMP), and may be used in an amount that provides a desirable viscosity when including the positive electrode active material and optionally a binder and a conductive material. For example, the solid content concentration in the positive electrode slurry containing the positive electrode active material and optionally the binder and the conductive material is 10% by weight or more, 20% by weight or more, 30% by weight or more, 60% by weight or less, 50% by weight or less, and 40% by weight. It may be included as follows.

(2) cathode

The negative electrode can be manufactured by coating a negative electrode slurry containing a negative electrode active material, a binder, a conductive material, and a solvent on a negative electrode current collector, followed by drying and rolling.

The negative electrode current collector generally has a thickness of 3 ㎛ to 500 ㎛. Such a negative electrode current collector may have high conductivity without causing chemical changes in the battery, and may be, for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or carbon on the surface of copper or stainless steel. , surface treated with nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, like the positive electrode current collector, the bonding power of the negative electrode active material can be strengthened by forming fine irregularities on the surface, and can be used in various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven materials.

In addition, the negative electrode active material is lithium metal, a carbon material capable of reversibly intercalating/deintercalating lithium ions, a metal or an alloy of these metals and lithium, a metal complex oxide, and a material capable of doping and dedoping lithium. It may include at least one selected from the group consisting of materials and transition metal oxides.

As the carbon material capable of reversibly intercalating/deintercalating lithium ions, carbon-based anode active materials commonly used in lithium secondary batteries can be used, representative examples of which include crystalline carbon, amorphous carbon, or these. Can be used together. Examples of the crystalline carbon include graphite such as amorphous, plate-shaped, flake, spherical or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon (low-temperature calcined carbon). Alternatively, hard carbon, mesophase pitch carbide, calcined coke, etc. may be mentioned.

Examples of the above metals or alloys of these metals and lithium include Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al. and Sn, or an alloy of these metals and lithium may be used.

The metal complex oxides include PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , Bi _{2 O 5} , Li _x Fe ₂ O ₃ (0≤x≤1), Li _x WO ₂ (0≤x≤1 _{) and Sn} Pb, Ge; Me': A group consisting of Al, B, P, Si, elements of groups 1, 2, and 3 of the periodic table, halogen; 0<x≤1;1≤y≤3; 1≤z≤8) Any one selected from can be used.

Materials capable of doping and dedoping lithium include Si, _SiO It is an element selected from the group consisting of rare earth elements and combinations thereof, but not Si), Sn, SnO ₂ , Sn-Y (Y is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element, transition metal, rare earth elements selected from the group consisting of elements and combinations thereof, but not Sn), etc., and at least one of these may be mixed with SiO ₂ . The element Y includes Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, It may be selected from the group consisting of Te, Po, and combinations thereof.

Examples of the transition metal oxide include lithium-containing titanium complex oxide (LTO), vanadium oxide, and lithium vanadium oxide.

The negative electrode active material may be included in an amount of 80% to 99% by weight based on the total weight of solids in the negative electrode slurry.

The binder is a component that assists in bonding between the conductive material, the active material, and the current collector, and is usually added in an amount of 1 to 30% by weight based on the total weight of solids in the negative electrode slurry. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, Examples include polyethylene, polypropylene, ethylene-propylene-diene monomer, styrene-butadiene rubber, fluorine rubber, and various copolymers thereof.

The conductive material is a component to further improve the conductivity of the negative electrode active material, and may be added in an amount of 1 to 20% by weight based on the total weight of solids in the negative electrode slurry. These conductive materials may be conductive without causing chemical changes in the battery, and include, for example, carbon powder such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; Graphite powder such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; Conductive fibers such as carbon fiber and metal fiber; Conductive powders such as fluorinated carbon powder, aluminum powder, and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

The solvent may include water or an organic solvent such as NMP or alcohol, and may be used in an amount that provides a desirable viscosity when including the negative electrode active material and optionally a binder and a conductive material. For example, the solid content concentration in the slurry containing the negative electrode active material and optionally the binder and the conductive material may be 50% by weight or more, 55% by weight or more, 60% by weight or more, 75% by weight, or less, and 65% by weight or less. there is.

(3) Separator

The separator included in the lithium secondary battery of the present invention is a commonly used porous polymer film, such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer, and ethylene/methacrylate. Porous polymer films made of polyolefin-based polymers such as copolymers can be used alone or by laminating them, or conventional porous non-woven fabrics, such as high-melting point glass fibers, polyethylene terephthalate fibers, etc., can be used. there is.

The external shape of the lithium secondary battery of the present invention may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement it. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein.

Synthesis example

Each compound was synthesized using the method below.

Synthesis Example 1

Add 5 g of 3-butene-1,2-diol, 11.5 g of Na ₂ S ₂ O ₅ , and 10 g of water to the flask, maintain pH 7.3, and heat at 65°C. It was stirred for 9 hours. The reaction solution was concentrated by distillation under reduced pressure, and 50 mL of methanol was added to obtain a precipitate. The precipitate was filtered under reduced pressure and dried in a vacuum oven to obtain 10 g of sodium 3,4-dihydroxybutane sulfonate.

Then, 10 g of dried sodium 3,4-dihydroxybutane sulfonate, 0.2 g of DMF, and 70 g of THF were added to the flask, and 10 g of thionyl chloride was slowly added dropwise at 0°C. After the dropwise addition was completed, the reactant was heated at 60°C for 2 hours, and then the heated reactant was cooled to room temperature and HCl and MeOH were added. Afterwards, the reactant was passed through a silica column and concentrated under reduced pressure to obtain 5 g of 3-hydroxymethyl-1,3-propane sultone.

Then, add 30 g of diethyl acetate (DMC) and 3 g of pyridine to the flask and add 1,3-Dichloro-1,1,3,3-tetramethyldisiloxane (4). g was slowly added at 0°C. After stirring at room temperature for 30 minutes, 5 g of 3-hydroxymethyl-1,3-propane sultone obtained previously was dissolved in 20 g of dimethyl acetate (DMC) and slowly added. After reacting for 2 hours, the product was extracted into the organic layer using water and dimethyl acetate, and the extracted organic layer was concentrated to 5,5`-(((1,1,3,3-tetramethyldisiloxane-1, 3-diyl)bis(oxy))bis(methylene))bis(1,2-oxathiolane 2,2-dioxide), a compound represented by the following chemical formula 1-a was obtained.

[Compound 1-a]

The synthesis of the above compound was confirmed by ¹ H-NMR.

¹ H-NMR (500MHz, Bruker, ACN-d3) = 4.8(2H), 4.18(2H), 4.05(2H), 3.30(4H), 2.55(2H), 2.3(2H), 1.1(12H)

Synthesis Example 2

Add 5 g of 3-butene-1,2-diol, 11.5 g of Na ₂ S ₂ O ₅ , and 10 g of water to the flask, maintain pH 7.3, and heat at 65°C. It was stirred for 9 hours. The reaction solution was concentrated by distillation under reduced pressure, and 50 mL of methanol was added to obtain a precipitate. The precipitate was filtered under reduced pressure and dried in a vacuum oven to obtain 10 g of sodium 3,4-dihydroxybutane sulfonate.

Then, 10 g of dried sodium 3,4-dihydroxybutane sulfonate, 0.2 g of DMF, and 70 g of THF were added to the flask, and 10 g of thionyl chloride was slowly added dropwise at 0°C. After the dropwise addition was completed, the reactant was heated at 60°C for 2 hours, and then the heated reactant was cooled to room temperature and HCl and MeOH were added. Afterwards, the reactant was passed through a silica column and concentrated under reduced pressure to obtain 5 g of 3-hydroxymethyl-1,3-propane sultone.

Then, 30 g of diethyl acetate (DMC) and 3 g of pyridine were added to the flask, and 4.2 g of methanedisulfonyl dichloride was slowly added at 0°C. After stirring at room temperature for 30 minutes, 5 g of 3-hydroxymethyl-1,3-propane sultone obtained previously was dissolved in 20 g of dimethyl acetate (DMC) and slowly added. After reacting for 2 hours, the product was extracted into the organic layer using water and dimethyl acetate, and the extracted organic layer was concentrated to form bis((2,2-dioxido-1,2-oxathiolan-5-yl) Methyl)methanedisulfonate (bis((2,2-dioxido-1,2-oxathiolan-5-yl)methyl)methanedisulfonate), a compound represented by the following chemical formula 1-b was obtained.

[Formula 1-b]

The synthesis of the above compound was confirmed by ¹ H-NMR.

¹ H-NMR (500MHz, Bruker, ACN-d3) = 5.5(2H), 4.9(2H), 4.28(2H), 4.15(2H), 3.35(4H), 2.6(2H), 2.4(2H)

Synthesis Example 3

Add 5 g of 3-butene-1,2-diol, 11.5 g of Na ₂ S ₂ O ₅ , and 10 g of water to the flask, maintain pH 7.3, and heat at 65°C. It was stirred for 9 hours. The reaction solution was concentrated by distillation under reduced pressure, and 50 mL of methanol was added to obtain a precipitate. The precipitate was filtered under reduced pressure and dried in a vacuum oven to obtain 10 g of sodium 3,4-dihydroxybutane sulfonate.

Then, 10 g of dried sodium 3,4-dihydroxybutane sulfonate, 0.2 g of DMF, and 70 g of THF were added to the flask, and 10 g of thionyl chloride was slowly added dropwise at 0°C. After the dropwise addition was completed, the reactant was heated at 60°C for 2 hours, and then the heated reactant was cooled to room temperature and HCl and MeOH were added. Afterwards, the reactant was passed through a silica column and concentrated under reduced pressure to obtain 5 g of 3-hydroxymethyl-1,3-propane sultone.

Then, 30 g of diethyl acetate (DMC) and 3 g of pyridine were added to the flask, and 3.3 g of glutaryl chloride was slowly added at 0°C. After stirring at room temperature for 30 minutes, 5 g of 3-hydroxymethyl-1,3-propane sultone obtained previously was dissolved in 20 g of dimethyl acetate (DMC) and slowly added. After reacting for 2 hours, the product was extracted into the organic layer using water and dimethyl acetate, and the extracted organic layer was concentrated to form bis((2,2-dioxido-1,2-oxathiolan-5-yl) Methyl)glutarate (bis((2,2-dioxido-1,2-oxathiolan-5-yl)methyl)glutarate), a compound represented by the following chemical formula 1-c, was obtained.

[Formula 1-c]

The synthesis of the above compound was confirmed by ¹ H-NMR.

¹ H-NMR (500MHz, Bruker, ACN-d3) = 4.8(2H), 4.2(2H), 4.18(2H), 3.3(4H), 2.6(2H), 2.4(6H), 1.9(2H)

Synthesis Example 4

Add 5 g of 3-butene-1,2-diol, 11.5 g of Na ₂ S ₂ O ₅ , and 10 g of water to the flask, maintain pH 7.3, and heat at 65°C. It was stirred for 9 hours. The reaction solution was concentrated by distillation under reduced pressure, and 50 mL of methanol was added to obtain a precipitate. The precipitate was filtered under reduced pressure and dried in a vacuum oven to obtain 10 g of sodium 3,4-dihydroxybutane sulfonate.

Then, 10 g of dried sodium 3,4-dihydroxybutane sulfonate, 0.2 g of DMF, and 70 g of THF were added to the flask, and 10 g of thionyl chloride was slowly added dropwise at 0°C. After the dropwise addition was completed, the reactant was heated at 60°C for 2 hours, and then the heated reactant was cooled to room temperature and HCl and MeOH were added. Afterwards, the reactant was passed through a silica column and concentrated under reduced pressure to obtain 5 g of 3-hydroxymethyl-1,3-propane sultone.

Then, 30 g of diethyl acetate (DMC) and 3 g of pyridine were added to the flask, and 2.9 g of methyl dichlorophosphate was slowly added at 0°C. After stirring at room temperature for 30 minutes, 5 g of 3-hydroxymethyl-1,3-propane sultone obtained previously was dissolved in 20 g of dimethyl acetate (DMC) and slowly added. After reacting for 2 hours, the product was extracted into the organic layer using water and dimethyl acetate, and the extracted organic layer was concentrated to form bis((2,2-dioxido-1,2-oxathiolan-5-yl) Methyl)methyl phosphate (bis((2,2-dioxido-1,2-oxathiolan-5-yl)methyl)methyl phosphate), a compound represented by the following chemical formula 1-d was obtained.

[Formula 1-d]

The synthesis of the above compound was confirmed by ¹ H-NMR.

¹ H-NMR (500MHz, Bruker, ACN-d3) = 5.0(2H), 4.3(2H), 4.2(2H), 4.0(3H), 3.4(4H), 2.6(2H), 2.4(2H)

Example 1

LiPF 6 was dissolved in a non-aqueous solvent mixed with ethylene carbonate and ethyl methyl carbonate at a volume ratio of 3:7 so that the concentration of LiPF ₆ was 1.2 M, and then 99 g of the solution was taken. A non-aqueous electrolyte solution was prepared by adding 1g of the compound (Formula 1-a) synthesized in Synthesis Example 1 to the resulting solution.

Furthermore, the positive electrode active material (lithium nickel-cobalt-manganese oxide (Li(Ni _0.8 Co _0.1 Mn _0.1 )O ₂ )), conductive material (carbon black), and binder (polyvinylidene fluoride) were mixed at a weight ratio of 90:5:5. After mixing, it was added to N-methyl-2-pyrrolidone (NMP) to prepare a positive electrode slurry (solid content: 40% by weight). The positive electrode slurry was applied to a positive electrode current collector (Al thin film) with a thickness of 20 ㎛, then dried and roll pressed to prepare a positive electrode.

Separately, the negative electrode active material (artificial graphite), conductive material (carbon black), and binder (polyvinylidene fluoride) were mixed at a weight ratio of 90:5:5 and then mixed with N-methyl-2-pyrrolidone (NMP). was added to prepare a negative electrode slurry (solid content: 40% by weight). The negative electrode slurry was applied to a negative electrode current collector (Cu thin film) with a thickness of 20 ㎛, then dried and roll pressed to prepare a negative electrode.

Afterwards, an electrode assembly was manufactured by sequentially stacking the manufactured positive electrode, the polyolefin-based porous separator coated with inorganic particles (Al ₂ O ₃ ), and the manufactured negative electrode, and the assembled electrode assembly was stored in a coin-type battery case. A coin-type lithium secondary battery was manufactured by injecting the previously prepared non-aqueous electrolyte for lithium secondary battery.

Example 2

Example 1 above, except that the non-aqueous electrolyte solution prepared by adding the compound represented by Chemical Formula 1-b prepared in Synthesis Example 2 instead of the compound represented by Chemical Formula 1-a prepared in Synthesis Example 1 was used as the non-aqueous electrolyte solution. A lithium secondary battery was manufactured using the same method (see Table 1 below).

Example 3

Example 1 and A lithium secondary battery was manufactured using the same method (see Table 1 below).

Example 4

Example 1 and A lithium secondary battery was manufactured using the same method (see Table 1 below).

Comparative Example 1

A lithium secondary battery was manufactured in the same manner as Example 1 except that no compound was added when preparing the non-aqueous electrolyte solution in Example 1 (see Table 1 below).

Comparative Example 2

A lithium secondary battery was manufactured in the same manner as in Example 1, except that 1 g of ethylene sulfate was added when preparing the non-aqueous electrolyte solution in Example 1 (see Table 1 below).

Comparative Example 3

A lithium secondary battery was prepared in the same manner as in Example 1, except that 1 g of 1,3-propane sultone was added when preparing the non-aqueous electrolyte solution in Example 1 (see Table 1 below) ).

Comparative Example 4

A lithium secondary battery was prepared in the same manner as in Example 1, except that 1 g of a compound represented by the following formula

[Formula X]

Comparative Example 5

A lithium secondary battery was prepared in the same manner as in Example 1, except that 1 g of a compound represented by the following formula Y was added when preparing the non-aqueous electrolyte solution of Example 1 (see Table 1 below).

[Formula Y]

additive Additive content in non-aqueous electrolyte (% by weight) Example 1 Compound represented by Formula 1-a One Example 2 Compound represented by formula 1-b One Example 3 Compound represented by formula 1-c One Example 4 Compound represented by formula 1-d One Comparative Example 1 No additives used 0 Comparative Example 2 ethylene sulfate One Comparative Example 3 1,3-propane sultone One Comparative Example 4 Compound represented by formula One Comparative Example 5 Compound represented by formula Y One

Experimental Example 1. Evaluation of high temperature cycle characteristics of the battery

The batteries prepared in the above examples and comparative examples were activated with a constant current (CC) of 0.1 C. Subsequently, using a PESC05-0.5 charger/discharger (manufacturer: PNE Solutions Co., Ltd., 5 V, 500 Ma) at 25°C, charge was carried out with a CC of 0.33 C up to 4.2 V under constant current-constant voltage (CC-CV) charging conditions, and then with a CC of 0.05 C. Current cut of C was performed, and discharged at 0.33 C up to 2.5 V under constant current conditions. The charging and discharging was regarded as 1 cycle, and 2 cycles were performed. Next, it was fully charged with a constant current-constant voltage of 0.33 C/4.2 V, and discharged at 2.5 C for 10 seconds at SOC 50% to measure the voltage before and after discharge. The initial resistance was calculated using the voltage difference before and after discharge. did. Next, discharge until 2.5 V with a constant current of 0.33 C, then degas, and discharge to 4.2 V with a constant current of 0.33 C within the voltage driving range of 2.5 V to 4.2 V, respectively, under conditions of 45 ° C. The battery was charged until it was charged, and then charged at a constant voltage of 4.2 V, and charging was terminated when the charging current reached 0.05 C. After leaving the battery for 20 minutes, it was discharged at a constant current of 0.33 C until it reached 2.5 V. The charging and discharging was regarded as 1 cycle, and 100 cycles of charging and discharging were repeated.

At this time, the capacity after the first cycle and the capacity after the 100th cycle were measured using a PESC05-0.5 charger and discharger, and the capacity retention rate was calculated by substituting the capacity into [Equation 1] below.

[Equation 1]

Capacity retention rate (%) = (Capacity after 100 cycles/Capacity after 1 cycle) × 100

In addition, after performing 100 cycles, the discharge was performed at 2.5 C for 10 seconds at SOC 50% to measure the voltage before and after discharge, and the resistance value after 100 cycles was calculated using the voltage difference before and after discharge. The resistance increase rate was calculated by substituting the previously calculated initial resistance value and the resistance value after 100 cycles into [Equation 2] below.

[Equation 2]

Resistance increase rate (%) = {(resistance value after 100 cycles - initial resistance value)/initial resistance value} × 100

The capacity maintenance rate and resistance increase rate calculated for the batteries of each example and comparative example are summarized in Table 2 below.

Capacity maintenance rate (%) Resistance increase rate (%) Example 1 92 13 Example 2 92 13 Example 3 92 12 Example 4 93 12 Comparative Example 1 78 40 Comparative Example 2 86 35 Comparative Example 3 85 24 Comparative Example 4 88 19 Comparative Example 5 89 18

As shown in the results of Table 2 above, it can be confirmed that Examples 1 to 4 using the non-aqueous electrolyte additive of the present invention had a higher capacity retention rate and a lower resistance increase rate compared to Comparative Example 1 in which no additive was used, resulting in excellent cycle characteristics. In addition, even in Comparative Examples 2 and 3 in which existing non-aqueous electrolyte additives were used instead of the additives of the present invention, a lower capacity retention rate and a higher resistance increase rate were observed compared to the examples of the present invention, and when the non-aqueous electrolyte additives of the present invention were used, the cycle It was confirmed that a battery with particularly excellent characteristics could be manufactured.

In addition, Comparative Examples 4 to 4 in which Compounds 5 shows the capacity maintenance rate and resistance increase rate that are inferior to those of the embodiment of the present invention.

Experimental Example 2. Evaluation of high temperature storage characteristics of the battery

For the batteries manufactured in the above examples and comparative examples, the volume change rate and resistance increase rate after high temperature storage were measured by the method below.

1) Volume change rate (%)

After activating each cell with a constant current of 0.1 C, charge with a constant current of 0.33 C up to 4.2 V under constant current-constant voltage charging conditions using a PESC05-0.5 charger and discharger at 25 ° C, then proceed with a 0.05 C current cut; It was discharged at 0.33 C up to 2.5 V under constant current conditions. The charging and discharging was regarded as 1 cycle, and 2 cycles were performed. Next, it was fully charged with a constant current-constant voltage of 0.33 C/4.2 V, and discharged at 2.5 C for 10 seconds at SOC 50% to measure the voltage before and after discharge. The initial resistance was calculated using the voltage difference before and after discharge. did. Next, discharge until 2.5 V with a constant current of 0.33 C, then degas, and charge and discharge before a bowl filled with water at room temperature using TWD-150DM equipment (manufacturer: Two-pls). One battery was placed and the initial volume was measured. Afterwards, the battery was fully charged at 0.33 C/4.2 V constant current-constant voltage, stored at 60°C for 4 weeks (SOC 100%), and then the volume after high-temperature storage was measured in the same manner using the TWD-150DM equipment. did. The volume change rate was calculated by substituting the measured initial volume and the volume after high temperature storage into [Equation 3] below.

[Equation 3]

Volume change rate (%) = {(volume after high temperature storage - initial volume)/initial volume} × 100

2) Resistance increase rate (%)

The initial resistance was measured according to the process described above, discharged at a constant current of 0.33C until 2.5 V, degassed, and charged to 4.2 V. After being stored at 60°C for 4 weeks (SOC 100%), the resistance after high-temperature storage was measured while discharging again at 2.5°C for 10 seconds at SOC 50%. The resistance increase rate was calculated by substituting the initial resistance value measured as above and the resistance value after high temperature storage into [Equation 4] below.

[Equation 4]

Resistance increase rate (%) = {(resistance value after high temperature storage - initial resistance value)/initial resistance value} × 100

The volume change rate and resistance increase rate calculated for each battery using the method described above are summarized in Table 3 below.

Volume change rate (%) Resistance increase rate (%) Example 1 12 15 Example 2 12 15 Example 3 13 13 Example 4 11 12 Comparative Example 1 37 45 Comparative Example 2 30 35 Comparative Example 3 25 40 Comparative Example 4 18 20 Comparative Example 5 18 18

As shown in Table 3, compared to the batteries of Comparative Examples 1 to 3, the lithium secondary battery of the example generates less gas even after storage at high temperature, resulting in less change in volume and less increase in resistance, confirming that capacity characteristics can be stably maintained. did. In addition, the batteries of Comparative Examples 4 and 5 showed slightly inferior capacity retention and resistance increase rates compared to the Examples, and as explained in Experimental Example 1, there were disadvantages in terms of synthesis and storage, and also in terms of cycle characteristics. It has the disadvantage of being inferior to the example.

Claims (14)

Compound represented by Formula 1:
[Formula 1]

In Formula 1,
L ₁ and L ₂ are each independently directly bonded or a substituted or unsubstituted C ₁ to C ₆ alkylene group,
R ₁ and R ₂ are substituents represented by the following formula (2),
X is any one of the substituents represented by the following formulas 3 to 6,
n is any integer from 1 to 3,
[Formula 2]

In Formula 2,
* is the position binding to L ₁ or L ₂ ,
[Formula 3]

In Formula 3 above,
L ₃ to L ₆ are each independently directly bonded or a substituted or unsubstituted C ₁ to C ₆ alkylene group,
R ₃₁ to R ₃₈ are each independently hydrogen or a substituted or unsubstituted C ₁ to C ₆ alkyl group,
Y ₁ is a direct bond, -O-, or a substituted or unsubstituted C ₁ to C ₆ alkylene group,
* is the position bonding to the oxygen atom of Formula 1,
[Formula 4]

In Formula 4 above,
Y ₂ to Y ₄ are each independently a direct bond, -O-, or a substituted or unsubstituted C ₁ to C ₆ alkylene group,
* is the position bonding to the oxygen atom of Formula 1,
[Formula 5]

In Formula 5 above,
Y ₅ and Y ₆ are a direct bond, -N-, -O-, a substituted or unsubstituted C ₁ to C ₆ alkylene group, a substituted or unsubstituted C ₂ to C ₁₀ alkenylene group, or a substituted or unsubstituted alkenylene group. It is an alkynylene group of C ₂ to C ₁₀ ,
R ₄₁ to R ₄₄ are each independently hydrogen, a substituted or unsubstituted C ₁ to C ₆ alkyl group, or a substituted or unsubstituted C ₂ to C ₆ alkenyl group,
* is the position bonding to the oxygen atom of Formula 1,
[Formula 6]

In Formula 6 above,
L ₇ to L ₁₂ are each independently -O-, a direct bond, or a substituted or unsubstituted C ₁ to C ₆ alkylene group,
Y ₇ is a direct bond, -*, -O(R ₅ ), a substituted or unsubstituted C ₁ to C ₆ alkyl group, or a substituted or unsubstituted C ₁ to C ₆ alkoxy group,
R ₅ is a substituted or unsubstituted C ₂ to C ₆ alkenyl group,
* is the position bonding to the oxygen atom of Formula 1,
m and p are integers of 0 or 1, but when p is 1, Y ₇ is a direct bond, and m is 1.
In claim 1,
A compound wherein L ₁ and L ₂ are methylene groups.
In claim 1,
The compound where Y ₁ is a direct bond, -O-, or a substituted or unsubstituted alkylene group of C ₁ to C ₃ .
In claim 1,
The compound of Formula 3 is any one of the substituents represented by the following Formulas 3-a to 3-d:

In claim 1,
Y ₂ to Y ₄ are each independently a direct bond, -O-, or a substituted or unsubstituted C ₁ to C ₃ alkylene group, but when Y ₂ and Y ₃ are -O-, Y ₄ is substituted Or a compound having an unsubstituted C ₁ to C ₃ alkylene group.
In claim 1,
The compound of Formula 4 is any one of the substituents represented by the following Formulas 4-a to 4-f:

In claim 1,
When Y ₅ is -N- or -O-, Y ₆ is a direct bond.
In claim 1,
The compound of Formula 5 is any one of the substituents represented by the following Formulas 5-a to 5-j:

In claim 1,
L ₇ , L _{8 ,} L ₁₁ and L ₁₂ are each independently a direct bond or a substituted or unsubstituted C ₁ to C ₃ alkylene group.
In claim 1,
The compound of Formula 6 is any one of the substituents represented by the following Formulas 6-a to 6-i:

In claim 1,
The compound represented by Formula 1 is a compound represented by the following Formulas 1-a to 1-d:
[Formula 1-a]

[Formula 1-b]

[Formula 1-c]

[Formula 1-d]

lithium salt;
non-aqueous solvent; and
A non-aqueous electrolyte containing the compound according to any one of claims 1 to 11.
According to clause 12,
The non-aqueous electrolyte solution contains the compound in an amount of 0.01% by weight to 10% by weight based on the total weight of the non-aqueous electrolyte solution.
A lithium secondary battery containing the non-aqueous electrolyte according to claim 12.