KR20120132811A - Non-aqueous electrolyte comprising difluoro phosphate - Google Patents

Abstract

PURPOSE: A lithium secondary battery is provided to have excellent electrochemical performance and discharging capacity, and to remarkably improve charging and discharging cycle performance and battery life time. CONSTITUTION: A lithium secondary battery comprises a basic organic solvent which comprises lithium salt and carbonate-based solvent, and additives. The additive comprises difluorophosphate salt indicated in chemical formula 1, and one or more compounds selected from compounds comprising a trimethylsilyl group indicated in chemical formula 2-4. A lithium secondary battery comprises the non-aqueous electrolyte, an electrode part consisting of a positive electrode and a negative electrode facing to around the non-aqueous electrolyte, and a separator electrically separating a positive electrode and negative electrode.

Description

Non-aqueous electrolyte comprising difluoro phosphate

The present invention relates to a non-aqueous electrolyte lithium battery and a lithium secondary battery comprising the same, comprising a compound having a difluoro phosphate and a trimethyl silyl group.

The lithium secondary battery employing the nonaqueous electrolyte solution for lithium batteries according to the present invention exhibits excellent electrochemical characteristics and discharge capacity, and greatly improves battery output and charge / discharge cycle characteristics of lithium batteries.

Secondary batteries are chemical cells that can be used semi-permanently because they can be recharged unlike primary batteries. These secondary batteries are exponentially increasing in size due to the recent mass distribution of laptops, mobile communication devices, and digital cameras. Doing.

Secondary batteries include lead-acid batteries, nickel-cadmium (Ni-Cd) batteries, nickel-hydrogen (Ni-MH) batteries, and lithium batteries, depending on the negative electrode material and the positive electrode material. The density is determined. Among them, lithium secondary batteries are widely used as a driving power source for portable electronic devices such as laptops, camcorders or mobile phones because of their high energy density due to the low redox potential and molecular weight of lithium.

Among such lithium secondary batteries, a lithium secondary battery using a non-aqueous electrolyte solution includes a positive electrode coated with a metal with an active material such as a lithium metal mixed oxide capable of detaching and inserting lithium ions, and an active material such as carbon material or metal lithium. It includes a negative electrode coated on this metal. In addition, an electrolyte solution in which lithium salt is dissolved in an organic solvent is placed between these positive and negative electrodes.

The average discharge voltage of the lithium secondary battery is 3.6 ~ 3.7V, which can obtain a higher power than other secondary batteries such as alkaline batteries, Ni-MH batteries, or Ni-Cd batteries. Electrochemically stable electrolyte is required in the voltage range of 0 to 4.2V.

This electrolyte is a medium for transferring lithium ions between the positive electrode and the negative electrode, and must be stable in the operating voltage range of the battery and have the ability to transfer ions at a high speed. Therefore, in order to satisfy these conditions, the electrolyte solution contains a mixed solvent such as carbonate solvent such as ethylene carbonate, dimethyl carbonate, diethyl carbonate and aromatic hydrocarbon solvent such as fluorobenzene as an organic solvent, while LiPF ₆ , LiBF ₄ or LiN (C ₂ F ₅ SO ₃ ) ₂ and the like are included as lithium salts.

In such a lithium secondary battery, lithium ions (Li ⁺ ) existing in an ionic state in the electrolyte during initial charging are moved from the positive electrode to the negative electrode and inserted between the layers of the negative electrode coated with an active material such as carbon. However, such lithium ions have a large reactivity, and thus react with an active material such as carbon on the surface of the negative electrode to form compounds such as Li ₂ CO ₃ , Li ₂ O, or LiOH. These compounds form a passivation film on the surface of the negative electrode, which is called a solid electrolyte interface (SEI) film. This SEI film acts as an ion tunnel, allowing only lithium ions to be selectively inserted into the negative electrode. That is, the SEI film solvates lithium ions, thereby preventing the large molecular weight organic solvent molecules moving together with the lithium ions in the electrolyte from being inserted into the negative electrode and disrupting the structure of the negative electrode. Therefore, once the SEI film is formed, lithium ions do not cause side reactions with the negative electrode or other materials. Thus, no further decomposition of the electrolyte occurs and the amount of lithium ions in the electrolyte can be reversibly maintained to maintain stable charge and discharge of the lithium secondary battery (see J. Power Sources (1994) 51: 79-104). ). However, when the lithium secondary battery has a thin square shape, for example, in the process of forming the above-described SEI film or charging the lithium secondary battery, the carbonate-based organic solvent or the like is decomposed to form CO, CO. _The generation of gases such as ₂ , CH ₄ , C ₂ H _6, and the like, causes a problem of expanding the thickness of the lithium secondary battery (see J. Power Sources (1998) 72: 66-70). Moreover, during this process, further side reactions between the electrolyte and the positive electrode or the negative electrode occur to cause decomposition of the electrolyte, which causes a rapid decrease in the discharge capacity and life characteristics of the lithium secondary battery and There is also a problem that the internal resistance increases as time passes.

In order to solve this problem, compounds having various structures have been used in nonaqueous electrolytes as additives. Korean Unexamined Patent Publication No. 2005-0068669 and Korean Unexamined Patent Publication No. 2007-0073386 disclose a non-aqueous electrolyte solution containing trimethyl silyl borate or trimethyl silyl phosphate as an additive. However, there is still a need for the development of additives that can improve the properties of the non-aqueous electrolyte.

The present invention is to provide a new additive that can improve the discharge capacity and charge and discharge cycle characteristics of the lithium secondary battery to solve the above problems.

In addition, to provide a non-aqueous electrolyte containing the additive and a lithium secondary battery comprising the same.

Technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

A base organic solvent containing a lithium salt and a carbonate-based solvent, which contains, as an additive, at least one compound selected from a difluoro phosphate represented by the following formula (1) and a compound containing a trimethyl silyl group represented by the following formulas (2) to (4): A nonaqueous electrolyte solution is provided.

[Formula 1]

[Formula 2]

(3)

[Formula 4]

The present invention also provides a non-aqueous electrolyte according to the present invention; An electrode part including positive and negative electrodes positioned to face each other with the non-aqueous electrolyte interposed therebetween; And it provides a lithium secondary battery comprising a separator for electrically separating the positive electrode and the negative electrode. Other specific details of the embodiments of the present invention are included in the following detailed description and the accompanying drawings.

The lithium secondary battery including the non-aqueous electrolyte according to the present invention greatly improves the discharge capacity and the charge / discharge cycle characteristics according to the service period, and ultimately, the performance and the life of the lithium secondary battery are remarkably improved.

1 is a schematic diagram of a lithium secondary battery using a non-aqueous electrolyte solution according to one embodiment of the present invention as the electrolyte solution 130.
2 is a view showing a capacity change according to the cycle number of the lithium secondary battery including the non-aqueous electrolyte according to Examples 1 to 3 and Comparative Examples 1 to 2 of the present invention.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

In the present invention, at least one compound selected from a compound containing a difluoro phosphate represented by the following Chemical Formula 1 and a trimethyl silyl group represented by the following Chemical Formulas 2 to 4 is added to a basic organic solvent including a lithium salt and a carbonate solvent as an additive. It relates to a non-aqueous electrolyte solution, characterized in that it comprises.

[Formula 1]

[Formula 2]

(3)

[Formula 4]

Such an additive may reduce decomposition of the electrolyte or generation of various gases due to side reaction between the electrolyte and the positive electrode or the negative electrode when the lithium secondary battery is charged. Therefore, the discharge capacity and lifespan characteristics of the lithium secondary battery can be further improved, and the thickness expansion caused by the gas generation can also be reduced.

The configuration of the non-aqueous electrolyte solution is as follows. First, the non-aqueous electrolyte solution contains a basic organic solvent. At this time, the non-aqueous electrolyte solution does not contain water (H ₂ O) as defined by the term non-aqueous, but only an organic solvent.

Here, as the basic organic solvent, a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent or an aromatic hydrocarbon solvent may be used. More specifically, the basic organic solvent may be a solvent in which at least one selected from the group consisting of an ester solvent, an ether solvent, a ketone solvent, and an aromatic hydrocarbon solvent is mixed with a carbonate solvent. In this case, the carbonate solvent is made of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl propyl carbonate (EPC), dipropyl carbonate (DPC), methyl ethyl carbonate (MEC) and methyl propyl carbonate (MPC) At least one linear carbonate solvent selected from the group and at least one cyclic carbonate solvent selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) and vinylene carbonate (VC) This is preferred.

The cyclic carbonate-based solvent is large in polarity and sufficiently dissociates lithium ions, but has a disadvantage in that its ionic conductivity is small due to its large viscosity. Accordingly, when the linear carbonate solvent having a small polarity but a low viscosity is mixed with the cyclic carbonate solvent and included in the basic organic solvent of the non-aqueous electrolyte, the characteristics of the lithium secondary battery may be optimized.

In addition, the ester solvent that may be included in the basic organic solvent, butyrolactone (BL), decanolide, valerolactone, mevalolactone, caprolactone, methyl acetate, methyl propionic acid, ethyl propionic acid, n-methyl Acetate, n-ethyl acetate, n-propyl acetate or butyl acetate, and the like. Examples of the ether solvent include dibutyl ether and the like. The aromatic hydrocarbon solvent may include benzene, fluorobenzene, toluene, fluorotoluene, trifluorotoluene, xylene, and the like.

In addition, various organic solvents usable in the lithium secondary battery may be used without limitation, and two or more selected from the above organic solvents may be mixed and used.

On the other hand, in the case of using a solvent in which the carbonate solvent and the aromatic hydrocarbon solvent are mixed as the basic organic solvent, the basic organic solvent is 1: 1 to 30: 1 of the carbonate solvent and the aromatic hydrocarbon solvent. It may be included in the volume ratio.

The non-aqueous electrolyte solution further contains a lithium salt as a solute contained in the basic organic solvent. More specifically, the lithium salt is LiPF ₆ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAl0 ₄ , LiAlCl ₄ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (C ₂ F ₅ SO ₃ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ . One or more selected from the group consisting of LiN (C _× F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (where x and y are natural numbers), LiCl, and LiI may be used. In addition, various lithium salts usable in lithium secondary batteries can be used without limitation.

At this time, the lithium salt is preferably included in the non-aqueous electrolyte at a concentration of 0.6-2.0 M relative to the above-mentioned basic organic solvent. If the concentration of the lithium salt is less than 0.6M, the electrical conductivity of the non-aqueous electrolyte solution containing the same decreases, so that the performance of the non-aqueous electrolyte which transfers ions at high speed between the positive electrode and the negative electrode of the lithium secondary battery decreases, and 2.0 M When exceeded, the viscosity of the non-aqueous electrolyte is increased, so that the mobility of lithium ions is reduced, and the low temperature performance is lowered.

On the other hand, the non-aqueous electrolyte is a difluoro phosphate (hereinafter referred to as "PO ₂ F ₂ ') represented by the formula (1) and trimeryl silyl borate represented by the formula (2) together with the basic organic solvent and lithium salt (trimethylsilyl borate, hereinafter referred to as 'TMSB'), trimethylsilyl phosphate represented by Formula 3 (hereinafter referred to as 'TMSPa') and trimeryl silyl phosphite represented by formula 4 (hereinafter referred to as 'TMSPi') At least one compound selected from the group of the present invention) as an additive.

The content of the difluoro phosphate represented by the general formula (1) in the total non-aqueous electrolyte solution is 0.01 to 10% by weight, preferably 0.5 to 2% by weight, and the content of the compound containing the trimethyl silyl group represented by the general formulas (2 to 4) is 0.01 to 10 wt%, preferably 1-3 wt% is preferably included.

[Formula 1]

[Formula 2]

(3)

[Formula 4]

If the additive is included in less than 0.01 part by weight, the effect of improving the discharge capacity or lifespan characteristics of the lithium secondary battery is insignificant, and when included in excess of 10 parts by weight, the characteristics of the lithium secondary battery are rather deteriorated.

On the other hand, the specific action exhibited by using the additive in the non-aqueous electrolyte is as follows.

As is evident from the examples described below, the additive consisting of a compound comprising a compound of Formula 1 and at least one compound selected from Formulas 2 to 4 may be an electrolyte, a positive electrode, or a negative electrode when the lithium secondary battery is charged. The side reaction of can be suppressed from occurring. Therefore, it is possible to reduce the decomposition of the electrolyte or the generation of various gases such as CO, CO ₂ , CH ₄ , C ₂ H ₆ by the side reaction. Therefore, when the additive is added to the non-aqueous electrolyte, the discharge capacity and lifespan characteristics of the lithium secondary battery can be further improved, and the thickness expansion due to the gas generation can be reduced.

On the other hand, the above-mentioned non-aqueous electrolyte is stable in the temperature range of -20 ~ 60 ℃ to maintain a stable characteristic even at a voltage of 4V, thereby improving the safety and reliability of the lithium secondary battery. Therefore, the non-aqueous electrolyte solution can be applied to any lithium secondary battery such as a lithium ion battery, a lithium polymer battery, without limitation.

The present invention also provides a non-aqueous electrolyte solution according to one embodiment of the present invention described above; An electrode part including positive and negative electrodes positioned to face each other with the non-aqueous electrolyte interposed therebetween; And it provides a lithium secondary battery comprising a separator for electrically separating the positive electrode and the negative electrode.

FIG. 1 shows a schematic diagram of such a lithium secondary battery. In particular, LiCoO _{2 is used} as the active material of the positive electrode 100 and carbon (C) is used as the active material of the negative electrode, respectively. An embodiment of a lithium secondary battery used as) is schematically shown.

As shown in FIG. 1, a lithium secondary battery according to an exemplary embodiment of the present invention includes a positive electrode 100, a negative electrode 110, an electrolyte solution 130, and a separator 140. However, since the non-aqueous electrolyte solution as described above is sufficiently used as the electrolyte 130 for the lithium secondary battery, a detailed description of the configuration of the non-aqueous electrolyte solution will be omitted.

On the other hand, the positive electrode 100, for example, using a positive electrode active material coated on a metal such as aluminum. In this case, although LiCoO ₂ is used as the positive electrode active material in FIG. 1, LiCoO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiNiO _2, or LiN _1-xy Co _x M _y O ₂ (0 ≦ x ≦ 1, 0 ≤ y ≤ 1, 0 ≤ x + y ≤ 1, M may be a lithium intercalation compound such as a lithium metal oxide such as Al, Sr, Mg or La) or a lithium chalcogenide compound. In addition, without being limited thereto, any material usable as a positive electrode active material in a lithium secondary battery may be used.

In addition, the negative electrode 110 uses, for example, a negative electrode active material coated on a metal such as copper. In this case, in FIG. 1, for example, carbon (crystalline carbon or amorphous carbon) is used as the negative electrode active material, but in addition, carbon composites, lithium metals, lithium alloys, and the like may be used. Any material usable as the negative electrode active material in the secondary battery can be used.

At this time, the metal used for the positive electrode 100 and the negative electrode 110 is a voltage applied from the outside during charging, and serves to supply a voltage to the outside during discharge, the positive electrode active material is a current collector that collects positive charges ( collector), the negative electrode active material serves as a current collector to collect negative charges.

On the other hand, the separator 140 serves to electrically separate the positive electrode 100 and the negative electrode 110. As the separator 140, a single-layer separator made of polyethylene or polypropylene, a two-layer separator laminated with polyethylene / polypropylene, a three-layer separator laminated with polyethylene / polypropylene / polyethylene or polypropylene / polyethylene / polypropylene, and the like can be used. have.

Example 1

A positive electrode slurry was prepared by mixing LiCoO ₂ as a positive electrode active material, polyvinylidene fluoride (PVDF) as a binder, and carbon as a conductive agent at a weight ratio of 92/4/4, and then dispersing it in N-methyl-2-pyrrolidone. It was. The slurry was coated on an aluminum foil having a thickness of 20 μm, dried, and rolled to prepare a positive electrode.

Crystalline artificial graphite as a negative electrode active material and PVDF as a binder were mixed in a weight ratio of 92: 8, and then dispersed in N-methyl-2-pyrrolidone to prepare a negative electrode slurry. The slurry was coated on a copper foil having a thickness of 15 μm, dried, and rolled to prepare a negative electrode.

The positive electrode and the negative electrode thus prepared were wound and compressed using a polyethylene separator having a thickness of 16 μm and placed in a rectangular can of 30 mm × 48 mm × 6 mm.

In addition, 1.15 M of LiPF ₆ was added as a lithium salt to a non-aqueous organic solvent in which ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate (EC: EMC: DMC) was mixed at 1: 1: 1 to prepare a basic electrolyte solution. A nonaqueous electrolyte was prepared by adding 1 wt% of PO ₂ F _{2 and} 2 wt% of TMSB based on the total weight of the aqueous electrolyte.

Example 2

A nonaqueous electrolyte solution and a rectangular lithium secondary battery were prepared in the same manner as in Example 1, except that 2% by weight of TMSPa was added instead of TMSB in the nonaqueous electrolyte solution according to Example 1 above.

Example 3

A nonaqueous electrolyte solution and a rectangular lithium secondary battery were prepared in the same manner as in Example 1, except that 2 wt% of TMSPi was added instead of TMSB in the nonaqueous electrolyte solution according to Example 1 above.

Comparative Example 1

A nonaqueous electrolyte solution and a rectangular lithium secondary battery were prepared in the same manner as in Example 1 except that no additive was used in the nonaqueous electrolyte solution according to Example 1 above.

Comparative Example 2

A nonaqueous electrolyte solution and a rectangular lithium secondary battery were prepared in the same manner as in Example 1, except that TMSB was not used as an additive in the nonaqueous electrolyte according to Example 1, and only PO ₂ F ₂ was used as an additive.

Test Example 1. Discharge test at room temperature

Using a lithium secondary battery containing a non-aqueous electrolyte according to Examples 1 to 3 and Comparative Examples 1 to 2 above, after charging 0.2 C to 4.2 V at 25 ° C. room temperature, discharge was repeated 2 cycles at 2.75 V 0.2 C After that, the discharge capacities were compared.

As a result, as shown in Table 1, when the non-aqueous electrolyte solution according to Examples 1 to 3 was used, it was confirmed that the discharge capacity was improved by about 7% or more compared to Comparative Examples 1 to 2.

 Result of discharge capacity test at room temperature Room temperature discharge capacity (mAh / g) Improvement Example 1 948 7% for Comparative Example 2 Example 2 948 7% for Comparative Example 2 Example 3 950 7.2% relative to Comparative Example 2 Comparative Example 1 825 - Comparative Example 2 882 -

Test Example 2 Discharge Test at High Temperature

Using a lithium secondary battery containing a non-aqueous electrolyte according to Examples 1 to 3 and Comparative Examples 1 to 2 above, after charging 0.2 C to 4.2 V at 25 ° C. room temperature, after discharging at 2.75 V 0.2 C, again After 0.5 C charge to 4.2 V, the 2.75 V 0.2 C discharge capacity at 60 ° C. high temperature environment was compared.

As a result, as shown in Table 2, it was confirmed that the discharge capacity at a high temperature of about 6% or more was improved in the case of using the non-aqueous electrolyte solution according to Examples 1 to 3 compared to Comparative Examples 1 to 2.

Discharge capacity test result at high temperature High discharge capacity (mAh / g) Improvement Example 1 840 5.5% relative to Comparative Example 2 Example 2 841 5.5% relative to Comparative Example 2 Example 3 845 6.1% relative to Comparative Example 2 Comparative Example 1 730 - Comparative Example 2 795 -

Test Example 3 Discharge Test at Low Temperature

Using a lithium secondary battery containing a non-aqueous electrolyte according to Examples 1 to 3 and Comparative Examples 1 to 2 above, after charging 0.2 C to 4.2 V at 25 ° C. room temperature, after discharging at 2.75 V 0.2 C, again After 0.5 C charge to 4.2 V, the 2.75 V 0.2 C discharge capacity was compared at −30 ° C. low temperature environment.

As a result, as shown in Table 3, it was confirmed that the discharge capacity at a low temperature of about 6% or more was improved in the case of using the non-aqueous electrolyte solution according to Examples 1 to 3 compared to Comparative Examples 1 to 2.

Discharge capacity test result at low temperature Low Temperature Discharge Capacity (mAh / g) Improvement Example 1 480 6.0% relative to Comparative Example 2 Example 2 483 6.7% relative to Comparative Example 2 Example 3 488 7.5% relative to Comparative Example 2 Comparative Example 1 421 - Comparative Example 2 451 -

Test Example 4 Output Characteristics at Room Temperature and Low Temperature

Using a lithium secondary battery containing a non-aqueous electrolyte according to Examples 1 to 3 and Comparative Examples 1 to 2 above, after performing two cycles of charge and discharge at 25 ℃ room temperature, after charging 0.2C to 4.2V 2.75V 0.2 The discharge capacity at the time of C discharge was set as the initial capacity.

The room temperature output was obtained by discharging 10 seconds at 0.5C, 1C, 2C, and 4C, respectively, after charging 1C in a 25 ° C ambient temperature environment, and measuring the voltage at the 10th second.

The low-temperature output was obtained by discharging for 10 seconds at 0.5C, 1C, 2C, and 4C at -30 ° C low temperature environment after charging 1C in a 25 ° C room temperature environment, and measuring the voltage at the 10th second.

As a result, as shown in Table 4, when the non-aqueous electrolyte solution according to Examples 1 to 3 was used, the output at room temperature and low temperature was improved by about 4% or more compared with Comparative Examples 1 to 2.

Output characteristics at room temperature and low temperature Print(%) Room temperature output (%) Low temperature output (%) Output improvement rate (%) Example 1 91.8 87.1 4% or more relative to Comparative Example 2 Example 2 92.0 88.7 4.3% or more relative to Comparative Example 2 Example 3 93.0 89.4 5.2% or more relative to Comparative Example 2 Comparative Example 1 76.7 71.5 - Comparative Example 2 88.4 83 -

Test Example 5. Capacity after 500 cycles

Using a lithium secondary battery containing a non-aqueous electrolyte according to Examples 1 to 3 and Comparative Examples 1 to 2 above, after performing two cycles of charge and discharge at 25 ℃ room temperature, after charging 0.2C to 4.2V 2.75V 0.2 C discharge, and after charging 1C to 4.2V again and then 3V 2C discharge, the discharge capacity compared to the initial capacity after 500 cycles.

As a result, as shown in Table 5, when the non-aqueous electrolyte solution according to Examples 1 to 3 was used, it was confirmed that the capacity retention ratio was improved by about 7% or more compared to Comparative Examples 1 to 2.

Result of discharge capacity test at room temperature % Retention Improvement Example 1 95 7% for Comparative Example 2 Example 2 95 7% for Comparative Example 2 Example 3 96 8% for Comparative Example 2 Comparative Example 1 82 - Comparative Example 2 88 -

In addition, when the capacity retention ratio of the battery was compared for each cycle, as shown in FIG. 2, in the case of Examples 1 to 3, there was no significant decrease in capacity, whereas in Comparative Example 1 without using any additive, about 100 cycles were obtained. The capacity | capacitance was shown back and forth, and the comparative example 2 which used only DFBOP as an additive showed the sudden capacity | capacitance fall also about 350 cycles back and forth.

Claims (12)

A base organic solvent containing a lithium salt and a carbonate-based solvent, which contains, as an additive, at least one compound selected from a difluoro phosphate represented by the following formula (1) and a compound containing a trimethyl silyl group represented by the following formulas (2) to (4): Nonaqueous Electrolyte Features:
[Formula 1]

(2)

(3)

[Chemical Formula 4]

The non-aqueous electrolyte of claim 1, wherein the basic organic solvent is a solvent in which at least one selected from the group consisting of an ester solvent, an ether solvent, a ketone solvent, and an aromatic hydrocarbon solvent is mixed with a carbonate solvent. The method of claim 1, wherein the carbonate solvent is dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl propyl carbonate (EPC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC) and methyl At least one linear carbonate solvent selected from the group consisting of propyl carbonate (MPC) and at least one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) and vinylene carbonate (VC) A non-aqueous electrolyte solution comprising a cyclic carbonate solvent. The non-aqueous electrolyte solution of claim 2, wherein the aromatic hydrocarbon solvent comprises at least one selected from the group consisting of benzene, fluorobenzene, toluene, fluorotoluene, trifluorotoluene, and xylene. The method of claim 2, wherein the ester solvent is one selected from the group consisting of butyrolactone, decanolide, valerolactone, mevalolactone, caprolactone, n-methyl acetate, n-ethyl acetate, n-propyl acetate Non-aqueous electrolyte solution containing the above. The method of claim 1, wherein the lithium salt is LiPF ₆ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAl0 ₄ , LiAlCl ₄ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (C ₂ F ₅ SO ₃ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ . Non-aqueous electrolyte, characterized in that at least one selected from the group consisting of LiN (C _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (where x, y is a natural number), LiCl and LiI. According to claim 1, wherein the content of the compound containing the difluoro phosphate represented by the formula (1) and the trimethyl silyl group represented by the formula (2) to the total non-aqueous electrolyte is 0.5 to 2% by weight, 1 to 3% by weight, respectively A non-aqueous electrolyte solution. The non-aqueous electrolyte solution according to claim 1, wherein the lithium salt concentration in the basic organic solvent is 0.6 to 2.0 M. Non-aqueous electrolyte according to any one of claims 1 to 8; An electrode part including positive and negative electrodes positioned to face each other with the non-aqueous electrolyte interposed therebetween; And a separator for electrically separating the positive electrode and the negative electrode. The method of claim 9, wherein the positive electrode is LiCoO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiNiO ₂ and LiNi _1-xy Co _x M _y O ₂ (0≤x≤1, 0≤y≤1, 0≤x + y ≤ 1, M is Al, Sr, Mg or La) Lithium secondary battery, characterized in that the coating of at least one active material selected from the group consisting of. The lithium secondary battery of claim 9, wherein the negative electrode is coated with at least one active material selected from the group consisting of crystalline carbon, amorphous carbon, a carbon composite, lithium metal, and a lithium alloy. 10. The separator according to claim 9, wherein the separator is a single-layer separator made of polyethylene or polypropylene, a two-layer separator made of polyethylene / polypropylene, and a three-layer separator made of polyethylene / polypropylene / polyethylene or polypropylene / polyethylene / polypropylene. Lithium secondary battery, characterized in that one selected from the group consisting of.

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