KR102216069B1 - Electrolyte and lithium secondary cell comprising the same - Google Patents

Abstract

An electrolyte is provided. The electrolyte includes a base electrolyte containing a metal salt and an organic solvent, and a silane compound added to the base electrolyte and having a pi bond. Accordingly, decomposition of the metal salt contained in the base electrolyte is prevented and flame retardancy of the electrolyte is improved, so that a highly reliable lithium secondary battery having a long life and high safety at high temperature can be provided.

Description

Electrolyte and lithium secondary cell comprising the same {Electrolyte and lithium secondary cell comprising the same}

The present invention relates to an electrolyte and a lithium secondary battery including the same, and more particularly, to an electrolyte including a silane compound having a pi bond and a lithium secondary battery including the same.

With the development of portable mobile electronic devices such as smartphones, MP3 players, and tablet PCs and electric vehicles, the demand for lithium secondary batteries capable of storing electric energy is exploding.

However, the electrolyte used in lithium secondary batteries is easily burned by heat generated from the reaction with the high-temperature electrode.In particular, when an internal short circuit occurs due to dendrites growing at the negative electrode during overcharging, the temperature inside the battery is reduced. As it rises, there is a risk of battery explosion and fire. Accordingly, many researches and developments on flame retardant electrolytes to ensure the safety of lithium secondary batteries are in progress.

To solve this problem, Korean Patent Publication 10-2007-0023293 (application number 10-2005-0077720) discloses that when the temperature of the battery rises above a predetermined temperature, flame retardant gas is generated by endothermic reaction and the volume expands. A technology has been introduced to improve the safety of lithium secondary batteries by including expandable carbon in an electrolyte.

Meanwhile, when the electrolyte used in the lithium secondary battery contains LiPF ₆ salt, as shown in the following formula, hydrofluoric acid (HF) generated by decomposition of the LiPF ₆ salt contained in the electrolyte attacks the positive electrode active material of the lithium secondary battery. Thus, there is a problem in that the performance of the lithium secondary battery is deteriorated.

One technical problem to be solved by the present invention is to provide an electrolyte having flame retardancy and high safety, and a lithium secondary battery including the same.

Another technical problem to be solved by the present invention is to provide an electrolyte that minimizes decomposition of a lithium salt at high temperature and a lithium secondary battery including the same.

Another technical problem to be solved by the present invention is to provide an electrolyte having a long life and a lithium secondary battery including the same.

Another technical problem to be solved by the present invention is to provide a highly reliable electrolyte and a lithium secondary battery including the same.

In order to solve the above technical problem, the present invention provides an electrolyte.

The electrolyte includes a base electrolyte containing a metal salt and an organic solvent, and a silane compound added to the base electrolyte and having a pi bond.

The silane compound may include a compound represented by Formula 1 below.

<Formula 1>

In Formula 1, X is a linear or cyclic alkoxy system having 1 to 11 carbon atoms, and Y is any one selected from the group consisting of alkenyl-based, alkynyl-based, and acrylic-based having a pi bond having 1 to 11 carbon atoms, or It is any one selected from the group consisting of 6 to 11 aryl, phenyl, and benzyl, and n is a positive integer of 1=n=3.

The silane compound may include 0.1% to 30% by weight added.

The silane compound may include a Methacryloxy-based compound.

The silane compound may include at least one of 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-Acryloxypropyltrimethoxysilane.

The silane compound may include an Alkyl Silanes-based compound.

The silane compound may include at least one of Trimethylsily acetylene and Ethynyltriethylsilane.

The silane compound may include a Vinyl Silanes-based compound.

The silane compound is, Vinyltrimethoxysilane, Vinyltriethoxysilane, Vinyltris(2-methoxyethoxy)silane, Vinyltrisisopropoxysilane, Vinyltris(tert-butylperoxy)silane, Vinyldimethylethoxysilane, Vinylmethyldimethoxysilane, Vinylmethyldiethoxysilane, 1,1,3,3-tetramethyl-1,3-divinyldisiloxane, 2 ,4,6,8-tetramethyl-2,4,6,8-tetravinyl-cyclotetrasiloxane, or 1,3,5-Trivinyl-1,3,5-trimethylcyclotrisiloxane.

The silane compound may include a Phenyl-based compound.

The silane compound may include at least one of Phenyltrimethoxysilane, Phenyltriethoxysilane, Diphenyldimethoxysilane, Diphenyldiethoxysilane, Diphenyldihydroxysilane, Triphenylsilane, Dimethylphenylethoxysilane, Methyldiphenylethoxysilane, Methylphenyldimethoxysilane, or Methylphenyldiethoxysilane.

The silane compound may include Bis (trimethylsilyl) acetylene (BTMSA).

In order to solve the above technical problem, the present invention provides a lithium secondary battery.

The lithium secondary battery includes an electrolyte according to an embodiment of the present invention described above, and a positive electrode and a negative electrode disposed spaced apart from each other with the electrolyte interposed therebetween.

An electrolyte according to an embodiment of the present invention may include a base electrolyte and a silane compound having a pi bond added to the base electrolyte. Flame retardancy of the electrolyte may be improved by the silane compound having a pi bond, and the generation of hydrofluoric acid due to decomposition of the metal salt contained in the base electrolyte may be minimized. Accordingly, a high reliability lithium secondary battery having a long lifespan and high safety at high temperatures can be provided by preventing deterioration in charge/discharge characteristics due to hydrofluoric acid.

1 is a view for explaining a lithium secondary battery according to an embodiment of the present invention.
2 is a photograph for explaining the degree of decomposition of an electrolyte according to an embodiment of the present invention.
3 is a graph showing a result of measuring electrolytes according to an embodiment of the present invention by the linear scanning method.
4 is a graph illustrating charge/discharge characteristics of an electrolyte according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical idea of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete, and the spirit of the present invention may be sufficiently conveyed to those skilled in the art.

In addition, in the drawings, thicknesses of films and regions are exaggerated for effective description of technical content. Each embodiment described and illustrated herein also includes its complementary embodiment.

In the specification, expressions in the singular include plural expressions unless the context clearly indicates otherwise. In addition, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, elements, or a combination of the features described in the specification, and one or more other features, numbers, steps, and configurations It is not to be understood as excluding the possibility of the presence or addition of elements or combinations thereof.

Further, in the following description of the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

An electrolyte according to an embodiment of the present invention includes a base electrolyte and a silane compound added to the base electrolyte. The silane compound may be added in an amount of 0.1% to 30% by weight.

The base electrolyte may contain a metal salt and an organic solvent. The metal salt may be a lithium salt. For example, the lithium salt is, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiCF ₃ SO ₃ , LiC(SO ₂ CF ₃ ) ₃ , LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiAsF ₆ , LiSiF ₆ , or LiCH (CF ₃ SO ₂ ) ₂ It may include at least one of.

The organic solvent, for example, ethylene carbonate (ethylene carbonate), propylene carbonate (propylene carbonate), dimethyl carbonate (dimethyl carbonate), diethyl carbonate (diethyl carbonate), ethyl methyl carbonate (ethyl methyl carbonate), dimethoxyethane (dimethoxyethane), diethoxyethane (diethoxyethane), tetrahydrofuran (THF), or γ-butyrolactone (γ-butyrolactone) may include at least one of.

The silane compound may have a pi bond. According to an embodiment, the silane compound may include a compound represented by Formula 1 below.

In the <Formula 1>, X may be a linear or cyclic alkoxy system having 1 to 11 carbon atoms. Y is any one selected from the group consisting of alkenyl-based, alkynyl-based, and acryl-based having a pi bond of 1 to 11 carbon atoms, or any one selected from the group consisting of aryl-based, phenyl- and benzyl-based having 6 to 11 carbon atoms , n may be a positive integer of 1=n=3.

The silane compound may include a Methacryloxy-based compound having a pi bond. For example, the silane compound may include at least one of 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-Acryloxypropyltrimethoxysilane.

The silane compound may include an Alkyl Silanes-based compound having a pi bond. For example, the silane compound may include at least one of Trimethylsily acetylene and Ethynyltriethylsilane.

The silane compound may include a Vinyl Silanes-based compound having a pi bond. For example, the silane compound is, Vinyltrimethoxysilane, Vinyltriethoxysilane, Vinyltris(2-methoxyethoxy)silane, Vinyltrisisopropoxysilane, Vinyltris(tert-butylperoxy)silane, Vinyldimethylethoxysilane, Vinylmethyldimethoxysilane, Vinylmethyldiethoxysilane, 1,1,3,3-tetramethyl-1,3 -divinyldisiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl-cyclotetrasiloxane, or 1,3,5-Trivinyl-1,3,5-trimethylcyclotrisiloxane. .

The silane compound may include a Phenyl-based compound having a pi bond. For example, the silane compound may include at least one of Phenyltrimethoxysilane, Phenyltriethoxysilane, Diphenyldimethoxysilane, Diphenyldiethoxysilane, Diphenyldihydroxysilane, Triphenylsilane, Dimethylphenylethoxysilane, Methyldiphenylethoxysilane, Methylphenyldimethoxysilane, or Methylphenyldiethoxysilane.

The silane compound may include Bis (trimethylsilyl) acetylene (BTMSA) having a pi bond.

The silane compound may include two or more compounds selected from the above-described Methacryloxy-based compound, the above-described Alkyl Silanes-based compound, the above-described Vinyl Silanes-based compound, the above-described Phenyl-based compound, or Bis (trimethylsilyl) acetylene (BTMSA). .

The electrolyte according to the embodiment of the present invention described above may be included in a lithium secondary battery. Hereinafter, a lithium secondary battery including an electrolyte according to an embodiment of the present invention described above will be described with reference to FIG. 1.

1 is a view for explaining a lithium secondary battery according to an embodiment of the present invention.

Referring to FIG. 1, a lithium secondary battery according to an embodiment of the present invention includes a positive electrode 100 and a negative electrode 200 facing each other, an electrolyte 300 between the positive electrode 100 and the negative electrode 200, and a separator. It may include 400.

The electrolyte 300 disposed between the anode 100 and the separator 400, and between the cathode 200 and the separator 400 is, as described above, in the base electrolyte and the base electrolyte. It may contain a silane compound having an added pi bond.

The positive electrode 100 may include a positive electrode active material. For example, the positive electrode active material is LiMO ₂ (M = V, Cr, Co, Ni), LiM ₂ O ₄ (M = Mn, Ti, V), LiMPO ₄ (M = Co, Ni, Fe, Mn), LiNi _1-x Co _x O ₂ (0<x<1), LiNi _2-x Mn _x O ₄ (0<x<2), or Li[NiMnCo]O ₂ It may contain at least one material .

The negative electrode 200 may include a negative active material. For example, the negative active material is a carbon material such as graphite or hard carbon, a metal material such as Li, Na, Mg, Al, Si, In, Ti, Pb, Ga, Ge, Sn, Bi, Sb, or an alloy thereof , Silicon, or silicon oxide, or a Ti-based oxide such as Li ₄ Ti ₅ O ₁₂ .

The porosity of the separator 400 may be at least 30% or more, and the thickness of the separator 400 may be 5 to 30 μm. The separator 400 includes at least one selected from a polyolefin resin, a fluorine resin, a polyester resin, a polyacrylonitrile resin, or a microporous membrane made of a cellulose material, or an inorganic material such as ceramic is coated on these membranes. It may have been. For example, the polyolefin-based resin may include polyethylene, polypropylene, etc., the fluorine-based resin may include polyvinylidene fluoride, polytetrafluoroethylene, and the like, and the polyester-based resin may include polyethylene terephthalate. , Polybutylene terephthalate, etc. may be included.

Unlike the above-described embodiment, according to the lithium secondary battery according to the modified example of the embodiment of the present invention, any one of between the anode 100 and the separator 400 or between the anode 200 and the separator 400 In E, the electrolyte 300 including a silane compound having a pi bond may be disposed. In this case, the electrolyte 300 may be disposed between the positive electrode 100 with the positive electrode active material and the separator 400. Accordingly, decomposition of a metal salt (eg, lithium salt (LiPF ₆ )) by a silane compound having a pi bond is prevented, thereby suppressing the generation of hydrofluoric acid (HF) generated by the decomposition of the metal salt, and The positive active material can be efficiently protected from (HF).

According to an embodiment of the present invention, the electrolyte 300 included in the lithium secondary battery may include a silane compound having a pi bond added to the base electrolyte. Accordingly, it is possible to minimize the generation of hydrofluoric acid (HF) by decomposition of a metal salt (eg, lithium salt (LiPF ₆ )) contained in the base electrolyte. Accordingly, since hydrofluoric acid (HF) elutes the transition metal of the positive electrode active material, the charge/discharge characteristics of the lithium secondary battery are prevented from deteriorating, thereby providing a lithium secondary battery having a long life. In addition, the flame retardancy of the electrolyte may be improved by the silane compound, and accordingly, a highly reliable lithium secondary battery having high safety at high temperature may be provided.

Hereinafter, characteristics of an electrolyte according to an embodiment of the present invention and a lithium secondary battery including the same are compared and described.

Electrolyte preparation according to Examples and Comparative Examples

<Preparation of electrolyte according to examples>

A base electrolyte was prepared by adding 1M LiPF ₆ and 5% by weight of FEC to a solution in which the volume ratio of ethylene carbonate, ethylmethyl carbonate, and diethyl carbonate was 30:50:20, respectively, and silane was added to the base electrolyte. Compound was added.

The electrolyte according to Example 1 was prepared by adding 10% by weight of 3-Glycidoxypropyltrimethoxysilane as a silane compound having no pi bond to the base electrolyte.

The electrolyte according to Example 2 was prepared by adding 10% by weight of Tetraethyl orthosilicate as a silane compound having no pi bond to the base electrolyte.

The electrolyte according to Example 3 was prepared by adding 10% by weight of 3-Methacryloxypropyltrimethoxysilane as a Methacryloxy-based silane compound having a pi bond to the base electrolyte.

The electrolyte according to Example 4 was prepared by adding 10% by weight of Vinyltriethoxysilane as a Vinyl Silanes-based compound having a pi bond to the base electrolyte.

The electrolyte according to Example 5 was prepared by adding 10% by weight of Triethoxy(oct-7-en-1-yl)silane having a pi bond to the base electrolyte.

The electrolyte according to Example 6 was prepared by adding 2.5% by weight of Triphenylsilane as a Phenyl-based compound having a pi bond to the base electrolyte.

<Preparation of electrolyte according to comparative example>

As the electrolyte according to Comparative Example 1, the above-described base electrolyte solution used in Examples 1 to 6 was used.

Measurement of viscosity and ionic conductivity of electrolytes according to Examples and Comparative Examples

Table 1 below shows the measurement of the viscosity and ionic conductivity of electrolytes prepared according to Examples 1 to 6 and Comparative Example 1 described above. In Table 1 below, the viscosity of the electrolytes according to Examples and Comparative Examples was measured at 25°C using a viscometer. In the following <Table 1>, the ionic conductivity of the electrolytes according to Examples and Comparative Examples was measured using a conductivity measuring device while the electrolytes were maintained at 25°C.

Silane compound Pi combine Viscosity (cP) Ion conductivity (mS/cm) Comparative Example 1 Non-added none 2.84 8.7 Example 1 adding none 3.64 7.1 Example 2 adding none 3.29 7.3 Example 3 adding has exist 3.17 7.2 Example 4 adding has exist 3.8 7.2 Example 5 adding has exist 3.87 6.7 Example 6 adding has exist 5.67 7.7

Referring to <Table 1>, in the case of the electrolytes according to Examples 1 to 6 to which the silane compound was added, compared to the electrolyte according to Comparative Example 1 in which the silane compound was not added, the viscosity increased and the ionic conductivity was reduced by a small amount. It can be confirmed. In general, as the viscosity increased, the ionic conductivity of the electrolytes according to Examples 1 to 6 decreased according to the tendency of decreasing the ionic conductivity. However, it is expected that the ionic conductivity is reduced by a small amount, so that it is not related to the performance degradation of the lithium secondary battery.

Measurement of self-extinguishing time and hydrofluoric acid production of electrolytes according to Examples and Comparative Examples

Table 2 below shows the measurement of self-extinguishing time and the amount of hydrofluoric acid produced in the electrolytes prepared according to Examples 1 to 6 and Comparative Example 1 described above. In the following <Table 2>, the self-extinguishing time of the electrolytes according to Examples and Comparative Examples was measured as the time taken until the fire was completely turned off after lighting the same amount of electrolyte. In the following <Table 2>, the amount of hydrofluoric acid produced by the electrolytes according to Examples and Comparative Examples was measured by acid-base titration after storing the electrolytes at 55° C. for 3 days.

Silane compound Pi combine Self-extinguishing time (sec/g) Hydrofluoric acid generation (ppm) Comparative Example 1 Non-added none 196.0 492 Example 1 adding none 178.2 521 Example 2 adding none 113.7 800 Example 3 adding has exist 149.5 <10 Example 4 adding has exist 133.9 <10 Example 5 adding has exist 134.1 <10 Example 6 adding has exist 127.2 56

Referring to Table 2, it can be seen that the self-extinguishing time of the electrolytes according to Examples 1 to 6 in which the silane compound was added to the base electrolyte was reduced compared to the electrolyte according to Comparative Example 1 in which the silane compound was not added. have. Accordingly, it can be seen that using an electrolyte containing a silane compound is an effective method to improve the high temperature safety of a lithium secondary battery.

In particular, compared to the electrolyte to which the silane compound having no pi bond was added according to Examples 1 and 2, the electrolytes to which the silane compound having a pi bond was added according to Examples 3 to 6 reduced the self-extinguishing time, It can be seen that the amount of hydrofluoric acid produced was significantly reduced. Accordingly, it can be seen that using an electrolyte containing a silane compound having a pi bond is an effective method of improving the life of a lithium secondary battery by minimizing the generation of hydrofluoric acid due to decomposition of a metal salt in a lithium secondary battery.

2 is a photograph for explaining the degree of decomposition of an electrolyte according to an embodiment of the present invention.

Referring to Figure 2, as described with reference to <Table 2>, when a silane compound having a pi bond is added to the electrolyte, the metal salt (for example, lithium salt (LiPF ₆ )) contained in the electrolyte Decomposition is minimized. In order to confirm this, after leaving the electrolytes according to Comparative Examples 1 and 3 to 5 for 1 month without preventing moisture from penetrating into the electrolyte, browning of the electrolytes was confirmed.

As can be seen from FIG. 2, the electrolyte to which the silane compound having a pi bond was not added according to Comparative Example 1 clearly showed a browning phenomenon, but the electrolytes to which the silane compound having a pi bond was added according to Examples 3 to 5 You can see that the color has not changed. As a result, it can be confirmed that the silane compound having a pi bond suppresses the decomposition of the metal salt (eg, lithium salt (LiPF ₆ )) of the electrolyte.

Comparison of electrochemical properties of electrolyte

In order to compare the electrochemical properties of the electrolyte to which the silane compound having a pi bond is added, the electrolytes according to Examples 7 to 10 and the electrolyte according to Comparative Example 2 were prepared, and a lithium secondary battery was manufactured using the electrolytes.

<Preparation of electrolytes according to Examples 7 to 10>

A base electrolyte was prepared by adding 1.15 M of LIPF ₆ and 1% by weight of VC to a solution in which the volume ratio of ethylene carbonate and diethyl carbonate was 30:70, respectively, and a silane compound having a pi bond to the base electrolyte or A silane compound without pi bonds was added.

The electrolyte according to Example 7 was prepared by adding 10% by weight of 3-Methacryloxypropyltrimethoxysilane as a Methacryloxy-based silane compound having a pi bond to the base electrolyte.

The electrolyte according to Example 8 was prepared by adding 10% by weight of Vinyltriethoxysilane as a Vinyl Silanes-based compound having a pi bond to the base electrolyte.

The electrolyte according to Example 9 was prepared by adding 10% by weight of Triethoxy(oct-7-en-1-yl)silane having a pi bond to the electrolyte solution to the base electrolyte solution.

The electrolyte according to Example 10 was prepared by adding 10% by weight of Tetraethyl orthosilicate having no pi bond to the base electrolyte.

<Preparation of electrolyte according to Comparative Example 2>

As the electrolyte according to Comparative Example 2, the above-described base electrolyte solutions used in Examples 7 to 9 were used.

3 is a graph showing a result of measuring electrolytes according to an embodiment of the present invention by the linear scanning method.

Referring to FIG. 3, the electrolytes according to Examples 7 to 9 described above were measured by a linear sweep voltammetry method. It can be seen that the decomposition reaction of the electrolyte solution does not occur at a voltage of 5V or less. Accordingly, it can be confirmed that the electrolytes to which the silane compound having a pi bond is added are electrochemically safe within the operating range of the lithium secondary battery.

4 is a graph illustrating charge/discharge characteristics of an electrolyte according to an embodiment of the present invention.

<Preparation of a lithium secondary battery using an electrolyte according to Example 8>

Li (Ni _0.6 Co _0.2 Mn _0.2 ) O _{2 A} lithium secondary battery was manufactured using an electrolyte including a positive electrode, a graphite negative electrode, a polyethylene separator, and a silane compound having a pi bond according to Example 8 described above.

<Manufacture of a lithium secondary battery using an electrolyte according to Example 10>

Li (Ni _0.6 Co _0.2 Mn _0.2 ) O _{2 A} lithium secondary battery was manufactured using an electrolyte including a positive electrode, a graphite negative electrode, a polyethylene separator, and a silane compound having no pi bond according to Example 10 described above.

<Manufacture of a lithium secondary battery using the electrolyte according to Comparative Example 2>

Li (Ni _0.6 Co _0.2 Mn _0.2 ) O _{2 A} lithium secondary battery was manufactured using an anode, a graphite anode, a polyethylene separator, and an electrolyte to which a silane compound was not added according to Comparative Example 2 described above.

Referring to FIG. 4, charge/discharge tests were performed on lithium secondary batteries manufactured using electrolytes according to Examples 8 and 10 and Comparative Example 2. The charge/discharge test was performed at 55° C., an operating voltage of 2.9V to 4.3V, charging was performed at a constant current/constant voltage, and discharging was performed at a constant voltage.

Compared with the electrolyte to which the silane compound was not added, the electrolyte to which the silane compound was added without pi bonds, as described with reference to Table 2, reduced the self-extinguishing time but increased the amount of hydrofluoric acid produced. In this way, charging and the more the number of discharges increases, the LiPF ₆ is the amount of the produced HF decomposition contained in the electrolyte according to Example 10 and Comparative Example 2 LiPF ₆ decomposes included in the electrolyte according to the amount of the produced HF In addition, the positive electrode active material of the lithium secondary battery manufactured using the electrolyte according to Example 10 is relatively more attacked, so that the elution of the transition metal is increased. For this reason, it can be seen that the discharge capacity of the lithium secondary battery manufactured using the electrolyte according to Example 10 is significantly reduced compared to the lithium secondary battery manufactured using the electrolyte according to Comparative 2.

In addition, as the number of charging and discharging increases, the discharge capacity of the lithium secondary battery manufactured using the electrolyte to which the silane compound having a pi bond was added according to Example 8 decreased, whereas the silane compound was added according to Comparative Example 2. It can be seen that the discharge capacities of the lithium secondary battery manufactured using the non-rechargeable electrolyte and the lithium secondary battery manufactured using the electrolyte to which the silane compound having no pi bond was added according to Example 10 decreased relatively significantly. have. In the case of Example 8, the decomposition of LiPF ₆ contained in the electrolyte was prevented by the silane compound having a pi bond, thereby suppressing the generation of hydrofluoric acid, but in Comparative Examples 2 and 10, the decomposition of LiPF ₆ contained in the electrolyte It can be seen that a relatively large amount of hydrofluoric acid was generated, and the generated hydrofluoric acid attacked the positive electrode active material to elute the transition metal, thereby drastically reducing the capacity of the lithium secondary battery. In other words, it can be seen that an electrolyte containing a silane compound having a pi bond is an effective method of improving the charge/discharge characteristics of a lithium secondary battery.

In the above, the present invention has been described in detail using preferred embodiments, but the scope of the present invention is not limited to specific embodiments, and should be interpreted by the appended claims. In addition, those who have acquired ordinary knowledge in this technical field should understand that many modifications and variations can be made without departing from the scope of the present invention.

100: anode
200: cathode
300: electrolyte
400: separator

Claims (13)

A base electrolyte containing a metal salt containing hydrofluoric acid and an organic solvent; And
And a silane compound added to the base electrolyte and having a pi bond,
The silane compound includes triethoxy (oct-7-en-1-yl) silane,
The silane compound is an electrolyte comprising reducing the generation of hydrofluoric acid due to decomposition of the metal salt contained in the base electrolyte.
The method of claim 1,
The organic solvent includes ethylene carbonate, ethylmethyl carbonate and diethyl carbonate,
The metal salt includes LiPF ₆ ,
The base electrolyte solution further contains FEC (fluoroethylene carbonate),
The electrolyte comprising the silane compound is 10wt%.
The electrolyte according to claim 1; And
A lithium secondary battery comprising a positive electrode and a negative electrode disposed spaced apart from each other with the electrolyte therebetween.
The method of claim 3,
By the silane compound, the metal salt is decomposed to reduce generation of hydrofluoric acid,
A lithium secondary battery comprising reducing elution of the transition metal of the positive electrode active material included in the positive electrode into the electrolyte by hydrofluoric acid.

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