KR102600045B1 - Electrolyte Solution for Secondary Battery and Secondary Battery Comprising the Same - Google Patents

Abstract

The present invention relates to a non-aqueous electrolyte solution for secondary batteries and a secondary battery containing the same. The effect of improving lifespan characteristics and high-temperature storage characteristics by adding a salt represented by Formula 1 or Formula 2 to the non-aqueous electrolyte solution for secondary batteries according to the present invention. There is.

Description

Electrolyte solution for secondary batteries and secondary batteries containing the same {Electrolyte Solution for Secondary Battery and Secondary Battery Comprising the Same}

The present invention relates to an electrolyte for secondary batteries and a secondary battery containing the same, and more specifically, to the effect of improving lifespan and high-temperature storage characteristics by adding a salt represented by Formula 1 or Formula 2 to a non-aqueous electrolyte for lithium ion secondary batteries. It relates to a non-aqueous electrolyte for secondary batteries and a secondary battery containing the same.

Recently, portable electronic devices have become widely distributed, and accordingly, these portable electronic devices are becoming thinner, smaller, and lighter. Accordingly, efforts are being made to make secondary batteries used as power sources small and lightweight, capable of charging and discharging for a long time, and improving high-rate characteristics.

Secondary batteries include lead acid batteries, nickel-cadmium (Ni-Cd) batteries, nickel-hydrogen (Ni-MH) batteries, and lithium batteries, depending on the anode or cathode material, and have unique characteristics of the electrode materials. The potential and energy density are determined by. Among these, lithium secondary batteries have a high energy density due to the low oxidation/reduction potential and molecular weight of lithium, so they are widely used as a driving power source for portable electronic devices such as laptops, camcorders, and mobile phones. However, for lithium secondary batteries, the decrease in battery safety that occurs during continuous charging is a major problem. One of the causes that can affect the stability of a battery is heat generation due to structural collapse of the anode. Battery stability according to the operating principle of secondary batteries, especially non-aqueous electrolyte secondary batteries, is as follows. In other words, the cathode active material of a non-aqueous electrolyte secondary battery is made of lithium and/or a lithium-containing metal oxide that can occlude and release lithium ions, and such cathode active material is thermally unstable as a large amount of lithium is released when overcharged. transformed into a structure. In this overcharged state, when the battery temperature reaches a critical temperature due to external physical shock, such as exposure to high temperatures, oxygen is released from the cathode active material with an unstable structure, and the released oxygen causes an exothermic decomposition reaction with the electrolyte solvent. In particular, the combustion of the electrolyte is further accelerated by oxygen released from the anode, and this chain of exothermic reactions causes ignition and rupture of the battery due to thermal runaway. In addition, the positive transition metal deposited on the negative electrode acts as a catalyst that promotes the decomposition of the non-aqueous electrolyte, generating gas inside the battery, or the SEI layer of the negative electrode hinders the movement of lithium ions as charge/discharge progresses. Due to the problem, battery performance and efficiency are significantly reduced.

Therefore, in order to solve the above problems, Japanese Patent Publication No. 2013-157305 discloses an electrolyte solution containing a compound having two isocyanate groups, and Korean Patent No. 10-0412522 discloses di-t-butylsilylbis ( Although an electrolyte containing trifluoromethane sulfonate), trimethylsilylmethanesulfonate, trimethylsilyl benzenesulfonate, trimethylsilyl trifluoromethanesulfonate, and triethylsilyl trifluoromethanesulfonate is proposed, the lifespan is still high. There is a need for research on electrolytes with excellent properties and high-temperature storage characteristics.

Currently, there is a need for the development of additives that can improve the lifespan characteristics and high-temperature storage characteristics of secondary batteries.

Accordingly, as a result of diligent efforts to solve the above problems, the present inventors confirmed that adding an alkenyl sulfonate salt or an alkenyl phosphonate salt to a non-aqueous electrolyte solution can improve lifespan characteristics and high-temperature storage characteristics. This invention has been completed.

The purpose of the present invention is to provide a non-aqueous electrolyte for secondary batteries with improved lifespan characteristics at room temperature and high temperature and output characteristics before and after high temperatures.

Another object of the present invention is to provide a secondary battery with excellent life characteristics at room temperature and high temperature and excellent output characteristics before and after high temperature.

In order to achieve the above object, (A) lithium salt; (B) non-aqueous organic solvent; and (C) a non-aqueous electrolyte solution for a secondary battery containing one or more additives selected from the group consisting of salts represented by Formula 1 and Formula 2.

[Formula 1]

[Formula 2]

In Formula 1 or Formula 2, R is an alkenyl group having 2 to 9 carbon atoms, and M ⁺ is imidazolium, pyridinium, pyrrolidinium, ammonium, or phosphonium. ) or sulfonium.

The present invention also provides: (a) a positive electrode comprising a positive electrode active material capable of storing and releasing lithium; (b) a negative electrode containing a negative electrode active material capable of inserting and releasing lithium; (c) the electrolyte solution for secondary batteries; and (d) a secondary battery including a separator.

The non-aqueous electrolyte solution according to the present invention has the effect of improving lifespan characteristics and high-temperature storage characteristics at room temperature and high temperature by adding a salt represented by Chemical Formula 1 or Chemical Formula 2.

Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. In general, the nomenclature used herein is well known and commonly used in the art.

In the present invention, it was confirmed that the room temperature lifespan and output characteristics of the secondary battery were significantly increased by adding one or more additives selected from the group consisting of the compound represented by Formula 1 and the salt represented by Formula 2 to the non-aqueous electrolyte solution of the secondary battery. did.

Accordingly, in one aspect, the present invention provides: (A) a lithium salt; (B) non-aqueous organic solvent; (C) Provides a non-aqueous electrolyte solution for a secondary battery containing at least one additive selected from the group consisting of a compound represented by Formula 1 and a salt represented by Formula 2.

[Formula 1]

[Formula 2]

In Formula 1 or Formula 2, R is an alkenyl group having 2 to 9 carbon atoms, and M ⁺ is imidazolium, pyridinium, pyrrolidinium, ammonium, or phosphonium. ) or sulfonium.

From another aspect, the present invention provides a cathode comprising: (a) a cathode active material capable of storing and releasing lithium; (b) a negative electrode containing a negative electrode active material capable of inserting and releasing lithium; (c) the electrolyte solution for secondary batteries; and (d) a secondary battery including a separator.

Hereinafter, the present invention will be described in detail.

The non-aqueous electrolyte solution for secondary batteries according to the present invention includes (A) lithium salt; (B) non-aqueous organic solvent; and (C) one or more additives selected from the group consisting of salts represented by Formula 1 and Formula 2.

[Formula 1]

[Formula 2]

In Formula 1 or Formula 2, R is an alkenyl group having 2 to 9 carbon atoms, and M ⁺ is imidazolium, pyridinium, pyrrolidinium, ammonium, or phosphonium. ) or sulfonium.

In the present invention, alkenyl groups having 2 to 9 carbon atoms may include vinyl, allyl, 1-butenyl, 2-butenyl, 3-butenyl, and isobutenyl groups, but are not limited thereto.

In the present invention, the compound represented by Formula 1 is triethylammonium ethenesulfonate, which is a compound represented by Formula 1-1, and ethenesulfonate 2-ethyl 4-, which is a compound represented by Formula 1-2. Ethenesulfonate 2-ethyl 4-methyl imidazolium, etenesulfonate N-methyl-2-pyrrolidinium, a compound represented by Chemical Formula 1-3, or Chemical Formula 1- The compound represented by 4, 1-ethenyl-1H-imidazol-3-ium ethenesulfonate, is It is preferably used, but is not limited thereto.

[Formula 1-1]

[Formula 1-2]

[Formula 1-3]

[Formula 1-4]

In addition, in the present invention, the compound represented by Formula 2 is triethylammonium vinylphosphonate, which is a compound represented by Formula 2-1, and 2-ethyl-4, which is a compound represented by Formula 2-2. -Methyl-1H-imidazol-3-ium vinylphosphonate (2-ethyl-4-methyl-1H-imidazol-3-ium vinylphosphonate), 1-methyl-2oxopyrroli, a compound represented by Chemical Formula 2-3 Din-1-ium vinylphosphonate (1-methyl-2-oxopyrrolidin-1-ium vinylphosphonate) or 1-vinyl-1H-imidazole-2-ium vinylphosphonate (1-methyl-2-oxopyrrolidin-1-ium vinylphosphonate), a compound represented by the formula 2-4 1-vinyl-1H-imidazol-3-ium vinylphosphonate) is preferably used, but is not limited thereto.

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

[Formula 2-4]

.

In the present invention, M ⁺ may be an organic cation represented by Formulas 3 to 9.

[Formula 3]

[Formula 4]

[Formula 5]

[Formula 6]

[Formula 7]

[Formula 8]

[Formula 9]

In Formulas 3 to 9, R ¹ is hydrogen, alkyl with 1 to 9 carbon atoms, alkoxy with 1 to 9 carbon atoms, alkenyl with 2 to 9 carbon atoms, or alkyne with 2 to 9 carbon atoms, and R ² to R ⁵ are each independently Halogen or alkyl with 1 to 9 carbon atoms, alkoxy with 1 to 9 carbon atoms, alkenyl with 2 to 9 carbon atoms, or alkyne with 2 to 9 carbon atoms.

In the present invention, one or more life performance enhancing additives selected from the group consisting of compounds represented by Formula A-1, Formula A-2, and Formula A-3 may be further included.

[Formula A-1]

vinyl carbonate

[Formula A-2]

vinyl ethylene carbonate

[Formula A-3]

fluoroethylene carbonate

In the present invention, at least one high temperature performance selected from the group consisting of compounds represented by the following Formula B-1, Formula B-2, Formula B-3, Formula B-4, Formula B-5, and Formula B-6 Enhancing additives may additionally be included.

[Formula B-1]

ethylene sulfate

[Formula B-2]

1,3-propene-1,3-sultone

[Formula B-3]

1,4-butane sultone

[Formula B-4]

1,3-propanediol cyclic sulfate

[Formula B-5]

4,4'-bi-1,3,2-dioxathiolane, 2,2,2',2'-tetroxide (4,4 2,2,2′’,2′’-tetroxide)

[Formula B-6]

2,4,8,10-Tetraoxa-3,9-dithiaspiro[5,5]undecane (2,4,8,10-Tetraoxa-3,9-dithiaspiro[5.5]undecane) or 3,3 ,9,9,-tetroxide (3,3,9,9-tetroxide)

In the present invention, one or more output performance improvement additives selected from the group consisting of compounds represented by Chemical Formula C-1, Chemical Formula C-2, Chemical Formula C-3, and Chemical Formula C-4 may be further included.

[Formula C-1]

Bis(triethylsilyl) sulfate

[Formula C-2]

Bis(trimethylsilyl) sulfate

[Formula C-3]

trimethylsilyl ethenesulfonate

[Formula C-4]

triethylsilyl ethenesulfonate

In the present invention, one or more high temperature and output performance improvement additives selected from the group consisting of compounds represented by Formula D-1, Formula D-2, Formula D-3, and Formula D-4 may be further included. there is.

[Formula D-1]

Lithium difluorophosphate

[Formula D-2]

Lithium-bis(oxalato)borate

[Formula D-3]

Lithium bis(fluorosulfonyl)imide

[Formula D-4]

Lithium difluoro bis(oxalato) phosphate

In the present invention, lithium salts used as solutes in the electrolyte include LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(CF ₃ SO ₂ ) ₂ , CF ₃ SO ₃ It may be one or more types selected from the group consisting of Li and LiC(CF ₃ SO ₂ ) ₃ . The concentration of lithium salt is preferably used within the range of 0.1M to 2.0M, more preferably 0.7M to 1.6M. If it is less than 0.1M, the conductivity of the electrolyte decreases and the electrolyte performance deteriorates, and 2.0M is used. If it is exceeded, there is a problem in that the viscosity of the electrolyte increases and the mobility of lithium ions decreases. These lithium salts act as a source of lithium ions within the battery and enable the operation of a basic lithium secondary battery.

In the present invention, the non-aqueous organic solvent may be at least one selected from the group consisting of linear carbonate, cyclic carbonate, linear ester, and cyclic ester, and the linear carbonate is dimethyl carbonate, diethyl carbonate, dipropyl carbonate, and methyl. It is one or more carbonates selected from the group consisting of propyl carbonate, ethylpropyl carbonate, ethylmethyl carbonate, and mixtures thereof, and the cyclic carbonate is ethylene carbonate (EC), propylene carbonate (PC), 1,2 -A group consisting of butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate (VC), vinylethylene carbonate and fluoroethylene carbonate. wherein the linear ester is at least one ester selected from the group consisting of methyl propionate, ethyl propionate, propyl acetate, butyl acetate and ethyl acetate, and the cyclic ester is gammabutyrolactone, It may be one or more esters selected from the group consisting of caprolactone and valerolactone. In the electrolyte solution according to an embodiment of the present invention, when the non-aqueous organic solvent is a mixed solvent of a linear carbonate solvent and a cyclic carbonate-based solvent, the mixing volume ratio of the linear carbonate solvent:cyclic carbonate solvent is 1:1 to 9:1. It may be used, preferably mixed at a volume ratio of 1.5:1 to 4:1.

In the present invention, the content of one or more additives selected from the group consisting of the compound represented by Formula 1 or the compound represented by Formula 2 is 0.01 to 10% by weight, preferably 0.01 to 5% by weight, based on the non-aqueous electrolyte solution. More preferably, it can be added at 0.1 to 1% by weight. If it is less than 0.01% by weight, there is a problem that high-temperature battery characteristics deteriorate, and if it exceeds 10% by weight, there is a problem that ionic conductivity decreases.

The electrolyte solution of the lithium ion secondary battery of the present invention usually maintains stable characteristics in the temperature range of -20 to 50 ° C. The electrolyte solution of the present invention can be applied to lithium ion secondary batteries, lithium ion polymer batteries, etc.

In the present invention, the anode material of the lithium secondary battery is LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , or LiNi _1-xy Co _{x My} O ₂ (0≤x≤1, 0≤y≤1, 0 ≤x+y≤1, M is a metal such as Al, Sr, Mg, La, etc.) lithium metal oxide is used, and crystalline or amorphous carbon, carbon composite, lithium metal, or lithium alloy is used as the cathode material. do. The active material is applied to a thin plate current collector to an appropriate thickness and length, or the active material itself is applied in the form of a film, wound or laminated with a separator, which is an insulator, to create an electrode group, and then placed in a can or similar container, and then placed in a trialkyl A lithium-ion secondary battery is manufactured by injecting a non-aqueous electrolyte solution containing silyl sulfate and a phosphite-based stabilizer. Resins such as polyethylene and polypropylene may be used as the separator.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, and it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples.

[Example]

Example 1

LiNi _0.8 Co _0.1 Mn _0.1 O ₂ as a positive electrode active material, polyvinylidene fluoride (PVdF) as a binder, and carbon black as a conductive material were mixed at a weight ratio of 95.6:2.2:2.2, and then N-methyl-2-pyrrolidone. A positive electrode slurry was prepared by dispersing. This slurry was coated on aluminum foil with a thickness of 20㎛, then dried and rolled to produce a positive electrode.

Natural graphite as a negative electrode active material, acetylene black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder were mixed in a weight ratio of 85:8:7 and dispersed in N-methyl-2-pyrrolidone to prepare a negative electrode active material slurry. did. This slurry was coated on copper foil with a thickness of 15㎛, then dried and rolled to prepare a cathode.

A film made of polyethylene (PE) with a thickness of 20㎛ between the manufactured electrodes. The separator was stacked, wound, and compressed to form a cell using a pouch measuring 6 mm thick x 35 mm wide x 60 mm long, and a lithium secondary battery was manufactured by injecting the following non-aqueous electrolyte solution.

For the electrolyte, LiPF ₆ was dissolved to 1.0M in a mixed solvent of ethylene carbonate (EC):ethylmethyl carbonate (EMC) (3:7 volume ratio), and then 0.1% by weight of triethylammonium ethenesulfonate was added. It was manufactured.

Example 2

A lithium secondary battery was manufactured in the same manner as in Example 1, except that 0.3% by weight of triethylammonium ethenesulfonate was added to the electrolyte solution for a secondary battery.

Example 3

A lithium secondary battery was manufactured in the same manner as in Example 1, except that 0.5% by weight of triethylammonium ethenesulfonate was added to the electrolyte solution for a secondary battery.

Comparative Example 1

A lithium secondary battery was manufactured in the same manner as in Example 1, except that triethylammonium ethenesulfonate was not added to the electrolyte solution for a secondary battery.

Comparative Example 2

A lithium secondary battery was manufactured in the same manner as in Example 1, except that 0.1% by weight of 1,3-propane sultone was added to the electrolyte solution for a secondary battery.

Comparative Example 3

A lithium secondary battery was manufactured in the same manner as in Example 1, except that 0.3% by weight of 1,3-propane sultone was added to the electrolyte solution for a secondary battery.

Comparative Example 4

A lithium secondary battery was manufactured in the same manner as in Example 1, except that 0.5% by weight of 1,3-propane sultone was added to the electrolyte solution for a secondary battery.

Comparative Example 5

A lithium secondary battery was manufactured in the same manner as in Example 1, except that 2% by weight of 1,3-propane sultone was added to the electrolyte solution for a secondary battery.

Added ingredients Example 1 Example 2 Example 3 Comparative Example 1 Comparative example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 4.2V, 25℃ Cycle test Life efficiency (%, 300cyc) 77.2% 74.3% 69.8% 64.9% 61.2% 63.4% 64.8% 67.8% 4.2V, 45℃
Cycle test Lifespan efficiency (%, 300cyc) 69.5% 64.7% 60.4% 34.1% 39.4% 41.5% 47.6% 51.9% High temperature storage evaluation (70℃, 1 week) Cell thickness change rate (%) 10.4% 12.4% 13.8% 31.9% 26.8% 21.6% 20.8% 10.3% EIS
Rate of change (%) 102.4% 103.7% 109.6% 142.5% 140.3% 136.8% 132.9% 127.9% DC-IR
Rate of change (%) 91.4% 96.6% 98.0% 133.3% 128.1% 114.4% 107.2% 104.6% Retention capacity retention rate (%) 75.5% 74.5% 72.1% 64.0% 68.4% 70.5% 72.4% 73.4% Recovery capacity recovery rate (%) 78.2% 75.4% 74.7% 68.5% 70.2% 71.5% 74.1% 76.4%

Examples 4 to 21

Example 1 was carried out in the same manner as in Example 1, except that life performance improvement additives, high temperature improvement additives, output improvement additives, or high temperature and output improvement additives were added in the amounts shown in Tables 2 to 4 below. .

Comparative Examples 4 to 22

Comparative Example 1 was carried out in the same manner as in Comparative Example 1, except that life performance improvement additives, high temperature improvement additives, output improvement additives, or high temperature and output improvement additives were added in the amounts shown in Tables 5 to 7 below. .

Physical property evaluation 1: Life evaluation

The manufactured battery was charged at 1C to 4.2V and then discharged at 1C to 3V. This process was repeated 300 times to measure the lifespan maintenance rate. The lifespan maintenance rate was evaluated at room temperature (25°C) and high temperature (45°C). Initial discharge capacity It is expressed as a percentage of 300 cycle discharge capacity.

Physical property evaluation 2: High temperature storage evaluation

1) Cell thickness: After charging at 1C to 4.2V and storing at high temperature (70℃) for 7 days, the thickness of the cell was measured and expressed as a percentage of the initial thickness.

2) EIS: After charging at 1C to 4.2V, apply an AC signal of 10mV and change the voltage frequency to 90000~0.05Hz to measure the initial EIS (Electrochemical impedance spectroscopy). After charging at 1C to 4.2V, store at high temperature (70℃ for 7 days) Then, after charging at 1C to 4.2V and discharging at 1C twice, the EIS was measured after storage at high temperature (70°C) in the same manner as the initial EIS measurement method.

3) DC-IR: The same method as physical property evaluation 2, but after charging at 1C to 4.2V and discharging at SOC50, the evaluation was performed and expressed as a percentage compared to the initial DC-IR.

4) Retention, recovery capacity: After charging at 1C to 4.2V, store at high temperature (70℃) for 7 days, discharge at 1C, 2.75V to measure retention capacity (discharge capacity), charge again at 1C, 4.2V to 1C , After discharging at 2.75V, the recovery capacity (discharge capacity) was measured and expressed as a percentage compared to the initial discharge capacity.

Added ingredients Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Triethylammonium
ethenesulfonate 0.1 0.1 0.1 0.1 0.1 0.1 0.1 propane sultone 2 Formula A-1 1.5 Formula A-2 1.5 Formula A-3 1.5 Formula B-1 2 Formula B-2 2 Formula B-3 2 Formula B-4 Formula B-5 Formula B-6 Formula C-1 Formula C-2 Formula C-3 Formula C-4 Formula D-1 Formula D-2 Formula D-3 Formula D-4 4.2V, 25℃ Cycle test Life efficiency (%, 300cyc) 86.5% 95.3% 93.4% 92.4% 84.2% 82.1% 81.4% 4.2V, 45℃
Cycle est Life efficiency (%, 300cyc) 71.8% 88.9% 87.6% 87.4% 73.4% 72.3% 71.6% High temperature storage evaluation (70℃, 1 week) Cell thickness change rate (%) 4.3% 9.1% 9.3% 10.1% 5.1% 8.4% 9.2% EIS
Rate of change (%) 80.4% 78.6% 93.1% 87.3% 78.5% 93.1% 87.3% DC-IR
Rate of change (%) 76.6% 80.5% 81.6% 79.4% 78.6% 82.5% 84.6% Retention capacity retention rate (%) 90.4% 88.4% 87.6% 88.6% 84.6% 83.7% 81.6% Recovery capacity recovery rate (%) 91.3% 87.6% 90.5% 87.8% 90.5% 87.8% 89.4%

Added ingredients Example 11 Example 12 Example 13 Example 14 Example 15 Example 16 Triethylammonium
ethenesulfonate 0.1 0.1 0.1 0.1 0.1 0.1 propane sultone Formula A-1 Formula A-2 Formula A-3 Formula B-1 Formula B-2 Formula B-3 Formula B-4 2 Formula B-5 2 Formula B-6 2 Formula C-1 One Formula C-2 One Formula C-3 One Formula C-4 Formula D-1 Formula D-2 Formula D-3 Formula D-4 4.2V, 25℃ Cycle test Life efficiency (%, 300cyc) 81.5% 82.4% 83.4% 82.1% 83.1% 82.6% 4.2V, 45℃
Cycle test Life efficiency (%, 300cyc) 72.6% 72.4% 73.1% 71.5% 72.5% 74.6% High temperature storage evaluation (70℃, 1 week) Cell thickness change rate (%) 8.6% 10.60% 10.4% 11.4% 12.8% 9.6% EIS
Rate of change (%) 88.4% 81.50% 86.4% 60.4% 68.4% 46.8% DC-IR
Rate of change (%) 79.4% 80.4% 80.7% 54.6% 53.4% 39.8% Retention capacity retention rate (%) 82.3% 83.4% 84.6% 78.4% 77.5% 80.4% Recovery capacity recovery rate (%) 88.4% 89.6% 84.6% 80.5% 80.8% 83.4%

Added ingredients Example 17 Example 18 Example 19 Example 20 Example 21 Triethylammonium
ethenesulfonate 0.1 0.1 0.1 0.1 0.1 propane sultone Formula A-1 Formula A-2 Formula A-3 Formula B-1 Formula B-2 Formula B-3 Formula B-4 Formula B-5 Formula B-6 Formula C-1 Formula C-2 Formula C-3 Formula C-4 One Formula D-1 One Formula D-2 One Formula D-3 One Formula D-4 One 4.2V, 25℃ Cycle test Life efficiency (%, 300cyc) 81.6% 81.8% 80.3% 80.4% 81.1% 4.2V, 45℃
Cycle test Life efficiency (%, 300cyc) 75.1% 73.4% 71.3% 70.8% 72.8% High temperature storage evaluation (70℃, 1 week) Cell thickness change rate (%) 8.4% 8.8% 10.1% 10.3% 9.3% EIS
Rate of change (%) 54.8% 61.3% 63.5% 62.4% 61.8% DC-IR
Rate of change (%) 43.4% 51.3% 58.6% 59.4% 53.2% Retention capacity retention rate (%) 81.1% 79.3% 81.6% 82.0% 79.1% Recovery capacity recovery rate (%) 83.9% 82.3% 80.1% 79.6% 81.8%

Added ingredients Comparative Example 6 Comparative example 7 Comparative example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 Triethylammonium
ethenesulfonate Formula A-1 1.5 Formula A-2 1.5 Formula A-3 1.5 Formula B-1 2 Formula B-2 2 Formula B-3 2 Formula B-4 2 Formula B-5 Formula B-6 Formula C-1 Formula C-2 Formula C-3 Formula C-4 Formula D-1 Formula D-2 Formula D-3 Formula D-4 4.2V, 25℃ Cycle test Life efficiency (%, 300cyc) 75.1% 74.6% 73.8% 59.7% 63.7% 59.4% 60.8% 4.2V, 45℃ Cycle test Life efficiency (%, 300cyc) 68.4% 63.4% 64.1% 40.5% 30.3% 28.7% 31.2% High temperature storage evaluation (70℃, 1 week) Cell thickness change rate (%) 21.4% 23.70% 24.5% 15.9% 17.8% 18.7% 20.5% EIS
Rate of change (%) 143.0% 152.50% 146.5% 124.0% 126.8% 130.6% 132.4% DC-IR
Rate of change (%) 126.7% 132.7% 130.4% 112.6% 126.7% 129.3% 127.3% Retention capacity retention rate (%) 68.2% 61.4% 60.8% 52.6% 53.8% 58.4% 54.6% Recovery capacity recovery rate (%) 67.5% 68.1% 62.4% 58.4% 60.3% 65.1% 61.4%

Added ingredients Comparative Example 13 Comparative Example 14 Comparative Example 15 Comparative Example 16 Comparative Example 17 Comparative Example 18 Comparative Example 19 1,3-propane sultone Formula A-1 Formula A-2 Formula A-3 Formula B-1 Formula B-2 Formula B-3 Formula B-4 Formula B-5 2 Formula B-6 2 Formula C-1 One Formula C-2 One Formula C-3 One Formula C-4 One Formula D-1 One Formula D-2 Formula D-3 Formula D-4 4.2V, 25℃ Cycle test Life efficiency (%, 300cyc) 65.3% 71.9% 62.6% 63.6% 65.4% 66.9% 65.4% 4.2V, 45℃
Cycle test Life efficiency (%, 300cyc) 50.8% 60.1% 45.6% 48.6% 52.4% 51.9% 48.6% High temperature storage evaluation (70℃, 1 week) Cell thickness change rate (%) 19.4% 19.6% 48.6% 49.6% 42.6% 43.8% 21.8% EIS
Rate of change (%) 131.0% 129.7% 103.4% 104.5% 108.1% 104.6% 105.4% DC-IR
Rate of change (%) 117.4% 116.6% 92.6% 95.4% 94.2% 93.1% 93.3% Retention capacity retention rate (%) 51.5% 52.8% 48.6% 47.6% 51.9% 52.4% 58.4% Recovery capacity recovery rate (%) 58.4% 59.4% 55.1% 54.6% 58.4% 59.7% 67.6%

Added ingredients Comparative Example 20 Comparative Example 21 Comparative example 22 1,3-propane sultone Formula A-1 Formula A-2 Formula A-3 Formula B-1 Formula B-2 Formula B-3 Formula B-4 Formula B-5 Formula B-6 Formula C-1 Formula C-2 Formula C-3 Formula C-4 Formula D-1 Formula D-2 One Formula D-3 One Formula D-4 One 4.2V, 25℃ Cycle test Life efficiency (%, 300cyc) 62.1% 61.8% 63.3% 4.2V, 45℃
Cycle test Life efficiency (%, 300cyc) 41.3% 40.8% 47.6% High temperature storage evaluation (70℃, 1 week) Cell thickness change rate (%) 25.6% 24.6% 21.4% EIS
Rate of change (%) 108.9% 109.6% 106.1% DC-IR
Rate of change (%) 96.9% 97.4% 94.6% Retention capacity retention rate (%) 54.1% 53.4% 59.4% Recovery capacity recovery rate (%) 62.6% 61.7% 65.4%

Example 22

In the electrolyte solution for a secondary battery of Example 1, 0.1% by weight of etenesulfonate 2-ethyl 4-methyl imidazolium (Formula 1-2) instead of triethylammonium ethenesulfonate. was carried out in the same manner as in Example 1, except for the addition of .

Example 23

In the electrolyte solution for a secondary battery of Example 1, 0.1% by weight of etenesulfonate N-methyl-2-pyrrolidinium (Formula 1-3) instead of triethylammonium ethenesulfonate. was carried out in the same manner as in Example 1, except for the addition of .

Example 24

In the electrolyte solution for a secondary battery of Example 1, 1-ethenyl-1H-imidazol-3-ium ethenesulfonate was used instead of triethylammonium ethenesulfonate. Formula 1-4) was carried out in the same manner as Example 1, except that 0.1% by weight was added.

Example 25

Example 1 and EXAMPLE 1, except that 0.1% by weight of triethylammonium vinylphosphonate (Chemical Formula 2-1) was added instead of triethylammonium ethenesulfonate in the electrolyte solution for secondary batteries of Example 1. The same procedure was performed.

Example 26

In the electrolyte solution for a secondary battery of Example 1, 2-ethyl-4-methyl-1H-imidazole-3ium vinylphosphonate (2-ethyl-4-methyl-1H-) was used instead of triethylammonium ethenesulfonate. The same procedure as Example 1 was performed except that 0.1% by weight of imidazol-3-ium vinylphosphonate (Formula 2-2) was added.

Example 27

In the electrolyte solution for a secondary battery of Example 1, 1-methyl-2-oxopyrrolidin-1-ium vinylphosphonate was used instead of triethylammonium ethenesulfonate. , Formula 2-3) was carried out in the same manner as Example 1, except that 0.1% by weight was added.

Example 28

In the electrolyte solution for a secondary battery of Example 1, 1-vinyl-1H-imidazol-3-ium vinylphosphonate was used instead of triethylammonium ethenesulfonate. Formula 2-4) was carried out in the same manner as Example 1, except that 0.1% by weight was added.

Added ingredients Example
22 Example
23 Example
24 Example
25 Example
26 Example
27 Example
28 4.2V, 25℃ Cycle test Life efficiency (%, 300cyc) 73.9% 73.5% 74.4% 74.2% 73.5% 73.9% 73.3% 4.2V, 45℃
Cycle test Life efficiency (%, 300cyc) 63.3% 64.1% 65.0% 65.1% 64.6% 64.1% 63.8% High temperature storage evaluation (70℃, 1 week) Cell thickness change rate (%) 12.2% 12.9% 12.5% 12.2% 12.8% 13.0% 13.2% EIS
Rate of change (%) 110.1% 109.2% 107.9% 104.1% 104.9% 105.5% 106.7% DC-IR
Rate of change (%) 100.9% 98.9% 100.2% 97.1% 99.4% 101.1% 98.8% Retention capacity retention rate (%) 73.3% 72.9% 71.7% 72.9% 70.9% 72.3% 71.5% Recovery capacity recovery rate (%) 75.1% 74.2% 74.9% 76.0% 74.4% 75.5% 74.0%

As shown in Tables 1 to 8, it can be seen that the electrolyte solutions of Examples 1 to 28 of the present invention have improved life evaluation and high temperature storage evaluation than Comparative Examples 1 to 22 in life evaluation and high temperature storage evaluation.

In the case of 1,3-propane sultone added in Comparative Examples 2 to 5, it is classified as a toxic substance and replacement additives are urgently needed. Due to its excellent high-temperature performance such as gas reduction performance, it is difficult to find replacement additives in terms of battery performance. However, from the results of the examples of the present invention, as an alternative additive to 1,3-propane sultone, it showed a very advantageous effect compared to 1,3-propane sultone not only in terms of battery performance but also in terms of the added content. It has been proven to be suitable for use.

As shown in Tables 1 to 8, it was confirmed that the electrolyte of the example of the present invention had improved high-temperature lifespan, reduced EIS and DC-IR, and significantly improved gas reduction performance compared to the comparative example.

Embodiments of the present invention have the effect of improving high temperature storage characteristics and high temperature lifespan characteristics.

The electrolyte solution of Example 1 showed excellent performance in high temperature storage evaluation, and battery performance was further improved when life performance improvement additives, high temperature improvement additives, and output improvement additives were additionally added as in Examples 4 to 21.

Examples 5 to 7, in which lifespan performance improvement additives were additionally added, improved lifespan efficiency compared to Example 1. Examples 8 to 13, in which high-temperature performance improvement additives were additionally added, improved EIS after high-temperature storage and further suppressed cell swelling compared to Example 1. Examples 14 to 17, in which output improvement additives were additionally added, had better output performance after high temperature storage than Example 1. In addition, Examples 18 to 21, in which additives in the form of salts were additionally added to improve both high temperature and output performance, suppressed cell swelling after high temperature storage and significantly improved EIS and output performance compared to Example 1. It has excellent effects.

As the specific parts of the present invention have been described in detail above, it is clear to those skilled in the art that these specific techniques are merely preferred embodiments and do not limit the scope of the present invention. will be. Accordingly, the actual scope of the present invention will be defined by the claims and their equivalents.

Claims (15)

Non-aqueous electrolyte for secondary batteries containing:
(A) Lithium salt;
(B) non-aqueous organic solvent; and
(C) one or more additives selected from the group consisting of salts represented by Formulas 1-1 to 1-4 and Formulas 2-1 to 2-4,
[Formula 1-1]

[Formula 1-2]

[Formula 1-3]

[Formula 1-4]

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

[Formula 2-4]
.
delete delete delete The non-aqueous electrolyte solution for a secondary battery according to claim 1, further comprising at least one life performance enhancing additive selected from the group consisting of compounds represented by Formula A-1, Formula A-2, and Formula A-3.
[Formula A-1]

[Formula A-2]

[Formula A-3]

The method of claim 1, wherein at least one high temperature performance selected from the group consisting of compounds represented by Formula B-1, Formula B-2, Formula B-3, Formula B-4, Formula B-5, and Formula B-6. A non-aqueous electrolyte for secondary batteries that additionally contains an improving additive.
[Formula B-1]

[Formula B-2]

[Formula B-3]

[Formula B-4]

[Formula B-5]

[Formula B-6]

The secondary battery according to claim 1, further comprising at least one output performance enhancing additive selected from the group consisting of compounds represented by Formula C-1, Formula C-2, Formula C-3, and Formula C-4. Aqueous electrolyte.
[Formula C-1]

[Formula C-2]

[Formula C-3]

[Formula C-4]

The secondary method of claim 1, further comprising at least one high temperature and output performance enhancing additive selected from the group consisting of compounds represented by Formula D-1, Formula D-2, Formula D-3, and Formula D-4. Non-aqueous electrolyte for batteries.
[Formula D-1]

[Formula D-2]

[Formula D-3]

[Formula D-4]

The method of claim 1, wherein the lithium salt is LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(CF ₃ SO ₂ ) ₂ , CF ₃ SO ₃ Li. And LiC(CF ₃ SO ₂ ) ₃ An electrolyte for a secondary battery, characterized in that it is at least one selected from the group consisting of.
The electrolyte solution for a secondary battery according to claim 9, wherein the lithium salt is contained in the non-aqueous organic solvent at a concentration of 0.6 to 2.0 M.
The electrolyte solution for a secondary battery according to claim 1, wherein the non-aqueous organic solvent is at least one selected from the group consisting of linear carbonate, cyclic carbonate, linear ester, and cyclic ester.
The method of claim 11, wherein the linear carbonate is one or more carbonates selected from the group consisting of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylmethyl carbonate, and mixtures thereof,
The cyclic carbonate includes ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, vinylethylene carbonate, and At least one carbonate selected from the group consisting of fluoroethylene carbonate,
The linear ester is one or more esters selected from the group consisting of methyl propionate, ethyl propionate, propyl acetate, butyl acetate and ethyl acetate,
The cyclic ester is an electrolyte for a secondary battery, wherein the cyclic ester is one or more esters selected from the group consisting of gammabutyrolactone, caprolactone, and valerolactone.
The electrolyte solution for a secondary battery according to claim 11, wherein the non-aqueous organic solvent is a mixture of linear carbonate and cyclic carbonate in a volume ratio of 1:1 to 9:1.
The electrolyte solution for secondary batteries according to claim 1, wherein the content of the compound represented by Formula 1 or Formula 2 is 0.1 to 10% by weight based on the electrolyte solution for secondary batteries.
Lithium secondary battery containing:
(a) a positive electrode containing a positive electrode active material capable of storing and releasing lithium;
(b) a negative electrode containing a negative electrode active material capable of inserting and releasing lithium;
(c) the electrolyte solution for secondary batteries according to any one of paragraphs 1 and 5 to 14; and
(d) Separator.