KR100578796B1 - Electrolyte for lithium secondary battery and lithium secondary battery comprising same - Google Patents

Abstract

The present invention provides a lithium secondary battery electrolyte and a lithium secondary battery comprising the same, the electrolyte has an A = O functional group (where A is an element capable of double bond with oxygen), and has a benzene ring at least one terminal Additives comprising the compound, non-aqueous organic solvents, and lithium salts.

The electrolyte solution of the present invention can improve the discharge capacity and discharge potential of the battery.

Benzophenone, lithium battery, electrolyte, discharge capacity

Description

ELECTROLYTE FOR RECHARGEABLE LITHIUM BATTERY AND RECHARGEABLE LITHIUM BATTERY COMPRISING SAME

1 is a view schematically showing the structure of a lithium secondary battery according to an embodiment of the present invention.

Figure 2 shows the redox reaction mechanism of benzophenone in the additive of the present invention.

3 is a graph showing the discharge curve of the lithium sulfur battery prepared according to Examples 1 to 3 and Comparative Example 1 of the present invention.

[Industrial use]

The present invention relates to a lithium secondary battery electrolyte and a lithium secondary battery comprising the same, and more particularly, to a lithium secondary battery electrolyte and a lithium secondary battery including the same, which can improve capacity.

[Prior art]

With the rapid development of the electric, electronic, telecommunication and computer industries, the demand for high performance and high safety secondary batteries has recently increased rapidly. In particular, secondary batteries, which are key components, are also required to be lighter in weight and smaller in size, due to light and short and portable trends of electric and electronic products. In addition, the necessity of the development of electric vehicles that can solve this problem has been increased as the need for a new type of energy supply and demand due to the exhaustion of oil and environmental pollution, such as air pollution and noise, due to the mass distribution of automobiles As a result, development of batteries having high power and high energy density has been demanded.

Lithium sulfur batteries and lithium secondary batteries of lithium ion batteries have been mainly studied as energy sources that meet these demands. In particular, one of the high-performance, next-generation high-tech new batteries, which has recently attracted the most attention, is lithium sulfur batteries. A lithium sulfur battery is a battery using sulfur (inorganic sulfur, S ₈ ) or a sulfur-based compound having a specific amount of 1675 mAh / g as a positive electrode active material and a lithium metal having a specific amount of 3860 mAh / g as a negative electrode active material. Therefore, the lithium sulfur battery is considered to be useful as a high capacity battery, but the lithium sulfur battery has not been usefully used for the following reasons.

Sulfur is reduced at the anode during discharging so that the sulfur-sulfur bond accepts and breaks electrons and forms various types of lithium polysulfides represented by Li ₂ S _n .

Lithium polysulfide is known to have solubility in electrolytes depending on the length of the sulfur, when n is 3 or more in a linear or cyclic ether solvent. As the discharge proceeds, the length of the sulfur chain of the lithium polysulfide is shortened, and theoretically, up to Li ₂ S is produced during full discharge. However, Li ₂ S ₂ and Li ₂ S in the discharge product are short in the length of the sulfur chain, so that the charge density of the sulfur anion increases, forming a stronger ionic bond with lithium ions are not dissolved in the electrolyte. Therefore, Li ₂ S ₂ is on, and so exist in sulfur cathode in a solid state theoretical capacity of electron transport and ion transport is hard to be discharged to a difficult Li ₂ S because of this lithium sulfur batteries, even though material though capable of discharging from Li ₂ S In comparison with this, the charge and discharge capacity is very low.

According to a study of a lithium sulfur battery using a dioxolane-based electrolyte solution by Peled et al. (J. electrochem. Soc, 1989, 136, 1621-1625), a solvent containing a high content of dioxolane is a lithium metal negative electrode. It is reported that the utilization rate of sulfur is less than 50% since the final discharge product is Li ₂ S ₂ .

Mikhaylik et al. Proposed a variety of sulfide-based materials as electron transfer mediators in US Pat. No. 6,569,573 B1 to improve the capacity of lithium sulfur batteries. This material reacts with Li ₂ S _2, which is reduced and then deposited on the cathode from the anode during discharge and itself acts to form Li ₂ S is oxidized and reduced to Li ₂ S _2.

However, all the conventional methods still have a problem of inducing a reaction up to Li ₂ S, which is the final product of the positive electrode active material, in a lithium sulfur battery, so that the charge and discharge capacity is significantly lower than the theoretical capacity.

 The present invention has been made to solve the above problems, and an object of the present invention is to provide an electrolyte solution for a lithium secondary battery that can increase the charge and discharge capacity.

Another object of the present invention is to provide an electrolyte solution for a lithium secondary battery that can improve the charge and discharge potential.

Still another object of the present invention is to provide a lithium secondary battery including the electrolyte.

In order to achieve the above object, the present invention provides an additive comprising a compound having an A═O functional group, wherein A is an element capable of double bonding with oxygen, and having a benzene ring at least on one end; Non-aqueous organic solvents; And it provides a lithium secondary battery electrolyte containing a lithium salt.

The invention also the electrolyte; A positive electrode including a positive electrode active material; And it provides a lithium secondary battery comprising a negative electrode comprising a negative electrode active material.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a lithium secondary battery, in particular a lithium secondary battery operating at an operating voltage of 0.8 to 3.0 V, more preferably Li ₂ S ₂ to Li ₂ S, the discharge product actually produced at the positive electrode upon discharge. An additive that exhibits the function of an electron transfer mediator capable of discharging is added to an electrolyte to improve battery capacity.

The additive used in the present invention preferably has a compound having an A═O functional group (wherein A is an element capable of double bond with oxygen) and at least one end group includes a benzene ring. Preferred examples of the A═O functional group include P═O, C═O or S═O. Most preferred examples of such compounds include compounds selected from the group consisting of the following Chemical Formulas 1 to 4.

[Formula 1]

In Formula 1, X ₁ to X ₁₀ are the same or independently selected from _{H, C n H 2n + 1} (n is an integer of 1 to 10), Br, Cl, F , OH, COOH, SO 3 H, each COO ^- M ⁺ , SO ₃ ^- M ⁺ , where M is Li, Na, K or Cs, C _n F _{2n + 1} (n is an integer from 1 to 10), NO ₂ or NH ₃ , preferably Cl or F is preferred.

[Formula 2]

In Formula 2, X ₁ to X ₅ are the same or independently selected from _{H, C n H 2n + 1} (n is an integer of 1 to 10), Br, Cl, F , OH, COOH, SO 3 H, each COO ^- M ⁺ , SO ₃ ^- M ⁺ , where M is Li, Na, K or Cs, C _n F _{2n + 1} (n is an integer from 1 to 10), NO ₂ or NH ₃ , preferably Cl or F,

X ₆ is H, C _n H _{2n + 1} , C _n H _2n OH, C _n H _2n OH, C _n H _2n COOH, C _n H _2n SO ₃ H, C _n H _2n COO ^- M ⁺ , C _n H _2n SO ₃ ^- M ⁺ , where M is Li, Na, K or Cs, C _n F _{2n + 1} , C _n F _2n OH, C _n F _2n COOH, C _n F _2n COO ^- M ⁺ ( here, M is Li, Na, K or Cs integer), C _n F _2n SO ₃ H or C _n F _2n SO ₃ ^- and M ⁺ is, preferably, C _n F _{2n + 1,} where n is 1 To an integer of 10.

[Formula 3]

In Formula 3, X ₁ to X ₁₀ are the same or independently selected from _{H, C n H 2n + 1} (n is an integer of 1 to 10), Br, Cl, F , OH, COOH, SO 3 H, each COO ^- M ⁺ , SO ₃ ^- M ⁺ , where M is Li, Na, K or Cs, C _n F _{2n + 1} , NO ₂ or NH ₃ , preferably Cl or F.

[Formula 4]]

In the formula 4, X ₁ to X ₅ are the same or independently selected from _{H, C n H 2n + 1} (n is an integer of 1 to 10), Br, Cl, F , OH, COOH, SO 3 H, each COO ^- M ⁺ , SO ₃ ^- M ⁺ , where M is Li, Na, K or Cs, C _n F _{2n + 1} , NO ₂ or NH ₃ , preferably Cl or F

X ₆ is H, C _n H _{2n + 1} , C _n H _2n OH, C _n H _2n OH, C _n H _2n COOH, C _n H _2n SO ₃ H, C _n H _2n COO ^- M ⁺ , C _n H _2n SO ₃ ^- M ⁺ , where M is Li, Na, K or Cs, C _n F _{2n +} 1, C _n F _2n OH, C _n F _2n COOH, C _n F _2n COO ^- M ⁺ , where M is Li, Na, K or Cs, C _n F _2n SO ₃ H or C _n F _2n SO ₃ ^- M ⁺ , preferably C _n F _{2n + 1} ,

n is an integer from 1 to 10.

The compounds represented by Chemical Formulas 1 to 4 may increase the reduction potential by introducing a group that attracts electrons to the benzene group, and thus function as an electron transfer mediator by introducing an appropriate X depending on the discharge potential of the main active material. Redox reaction potential that can have can be controlled.

The content of the additive is preferably 0.1 to 10% by weight, more preferably 1 to 5% by weight based on the total weight of the electrolyte solution of the present invention. When the content of the additive is less than 0.1% by weight, there is a problem that the effect of the additive is insignificant, and when the content of the additive exceeds 10% by weight, the ion conductivity of the electrolyte is reduced.

The redox reaction mechanism of benzophenone in which X ₁ to X ₁₀ are all H in the formula 1 is shown in FIG. 2. As shown in FIG. 2, the additive of the present invention has the property of reducing at the positive electrode with respect to the negative electrode, particularly the lithium negative electrode, and both the oxidation and the reducing agent may exist in a state dissolved in the electrolyte solution. The redox reaction of the additive of the present invention is shown in the range of 2.5 to 1.0V compared to lithium, preferably in the range of 2.3 to 1.4V, more preferably 2.0 to 1.7V.

The additive of the present invention is present in a dissolved state in the electrolyte, and when discharged, it is reduced by accepting electrons from the anode and the reduced additive is present in a dissolved state in the electrolyte. The reduced additives also react with Li ₂ S ₂ and Li ₂ S _n (n> 2) to oxidize to reduce lithium disulfide and lithium polysulfide. Therefore, when the additive of the present invention is used in a lithium sulfur battery, in a conventional lithium sulfur battery, Li ₂ S ₂ , which exists in a state in which electron transfer and ion transfer are blocked, is present as a solid in the electrolyte, resulting in a battery. As the reaction cannot proceed to Li ₂ S, the problem of reducing the battery capacity is solved, and Li ₂ S is formed with the reduced additive as the final product of the battery.

The electrolyte of the present invention also contains a non-aqueous organic solvent and a lithium salt. As this non-aqueous organic solvent, a single solvent may be used or two or more mixed organic solvents may be used. When using two or more mixed organic solvents, it is preferable to select one or more solvents from two or more groups among the weak polar solvent group, the strong polar solvent group, and the lithium metal protective solvent group.

Weak polar solvents are defined as those having a dielectric constant of less than 15 that can dissolve elemental sulfur among aryl compounds, bicyclic ethers, and acyclic carbonates; strong polar solvents include acyclic carbonates, sulfoxide compounds, lactone compounds, Among ketone compounds, ester compounds, sulfate compounds, and sulfite compounds, a dielectric constant capable of dissolving lithium polysulfide is defined as greater than 15, and lithium protective solvents are saturated ether compounds, unsaturated ether compounds, N, O, It is defined as a solvent having a charge and discharge cycle efficiency (cycle efficiency) of 50% or more to form a SEI (Solid Electrolyte Interface) film stable on a lithium metal, such as a heterocyclic compound containing S or a combination thereof.

 Specific examples of weak polar solvents include xylene, dimethoxyethane, 2-methyltetrahydrofuran, diethyl carbonate, dimethyl carbonate, toluene, dimethyl ether, diethyl ether, diglyme, tetraglyme and the like.

Specific examples of strong polar solvents include hexamethyl phosphoric triamide, gamma-butyrolactone, acetonitrile, ethylene carbonate, propylene carbonate, N-methylpyrrolidone, 3-methyl-2-oxazolidone , Dimethyl formamide, sulfolane, dimethyl acetamide, dimethyl sulfoxide, dimethyl sulfate, ethylene glycol diacetate, dimethyl sulfite, or ethylene glycol sulfite.

Specific examples of the lithium protective solvent include tetrahydrofuran, ethylene oxide, dioxolane, 3,5-dimethyl isoxazole, 2,5-dimethyl furan, furan, 2-methyl furan, 1,4-oxane, 4-methyldioxolane Etc.

The electrolytic salt lithium salt is lithium trifluoromethansulfonimide (lithium trifluoromethansulfonimide), lithium triflate (lithium triflate), lithium perchlorate (lithium perclorate), LiPF ₆ , LiBF ₄ or tetraalkylammonium, for example tetra One or more butylammonium tetrafluoroborate, or liquid salts at room temperature, such as imidazolium salts such as 1-ethyl-3-methylimidazolium bis- (perfluoroethyl sulfonyl) imide and the like Can be.

The lithium secondary battery including the electrolyte solution of the present invention includes a positive electrode and a negative electrode. As the cathode active material in the cathode, elemental sulfur (S ₈ ), a sulfur-based compound, or a mixture thereof may be used. The sulfur compound is Li ₂ S _n (n≥1), polysulfide (Li ₂ S _x , x≥2), 2,5-dimercapto-1,3,4-thiadiazole (DMct, 2,5 disulfide compounds such as -dimercapto-1,3,4-thiadiazole) or 1,3,5-trithiocyanuic acid (TTCA, 1,3,5-trithiocyanuic acid), organic sulfur compounds and carbon-sulfur polymers (( C ₂ S _x ) _n : x = 2.5 to 50, n≥2) can be selected from the group consisting of.

The negative electrode active material in the negative electrode is a group consisting of a material capable of reversibly intercalating or deintercalating lithium ions, a material capable of reacting with lithium ions to reversibly form a lithium-containing compound, a lithium metal and a lithium alloy. Can be selected from.

As a material capable of reversibly intercalating / deintercalating the lithium ions, any carbon-based negative electrode active material generally used in a lithium ion secondary battery may be used, and representative examples thereof include crystalline carbon. , Amorphous carbon or these can be used together. In addition, a representative example of a material capable of reacting with lithium ions to reversibly form a lithium-containing compound may include, but is not limited to, tin oxide (SnO ₂ ), titanium nitrate, silicon (Si), and the like. As the lithium alloy, an alloy of a metal selected from the group consisting of lithium and Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Al, and Sn may be used.

An inorganic protective layer, an organic protective layer, or a material in which these layers are stacked on a lithium metal surface may also be used as a cathode. As the inorganic protective film, Mg, Al, B, C, Sn, Pb, Cd, Si, In, Ga, lithium silicate, lithium borate, lithium phosphate, lithium phosphoronide, lithium silicon sulfide, lithium borosulfide, lithium aluminium It consists of a material selected from the group consisting of nosulfide and lithium phosphosulfide. The organic protective film is poly (p-phenylene), polyacetylene, poly (p-phenylene vinylene), polyaniline, polypyrrole, polythiophene, poly (2,5-ethylene vinylene), acetylene, poly (ferry) Naphthalene), polyacene, and poly (naphthalene-2,6-diyl), and a monomer, oligomer or polymer having conductivity selected from the group consisting of.

In addition, in the process of charging and discharging the lithium-sulfur battery, sulfur used as the positive electrode active material may be changed into an inert material and adhered to the surface of the lithium negative electrode. As described above, inactive sulfur refers to sulfur in which sulfur is no longer able to participate in the electrochemical reaction of the anode through various electrochemical or chemical reactions, and inert sulfur formed on the surface of the lithium cathode is a protective layer of the lithium cathode. There is also an advantage to act as. Therefore, lithium metal and inert sulfur formed on the lithium metal, for example lithium sulfide, may be used as the negative electrode.

In addition, a separator for preventing a short circuit between the positive electrode and the negative electrode in the lithium secondary battery may be included, and such a separator may be a polymer film such as polypropylene or polyethylene, or a multilayer thereof.

The lithium secondary battery including the electrolyte, the positive electrode, the negative electrode, and the separator described above may have a unit cell having a structure of a positive electrode / separator / cathode, a bicell having a structure of a positive electrode / separation membrane / cathode / isolate / anode, or a unit cell structure. It can be formed in the structure of a repeated laminated battery. The electrolyte solution is injected into the battery container containing the structure is present. The electrolyte solution of the present invention may be used as a liquid electrolyte solution, or may be used as a polymer electrolyte depending on materials and methods used in the manufacture of conventional polymer electrolytes.

A representative example of the lithium secondary battery of the present invention having such a configuration is shown in FIG. 1. 1 includes a positive electrode 2, a negative electrode 3, and a separator 4 positioned between the positive electrode 2 and the negative electrode 3, and an electrolyte solution between the positive electrode 2 and the negative electrode 3. The rectangular type lithium ion battery 1 including the case 5 in which the figure is shown is shown. Of course, the lithium secondary battery of the present invention is not limited to this shape, it is natural that any formation such as cylindrical, pouch, etc., including the positive electrode active material of the present invention and can operate as a battery.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only one preferred embodiment of the present invention and the present invention is not limited to the following examples.

(Comparative Example 1)

A positive electrode of a lithium sulfur battery having a capacity of ² mAh / cm ² was manufactured by a conventional method using 75 wt% of inorganic sulfur (S ₈ ) positive electrode active material, 15 wt% of carbon conductive material, and 10 wt% of polyethylene oxide binder. A lithium sulfur battery was manufactured using the positive electrode and a lithium metal foil negative electrode of 200 μm. The theoretical capacity of the prepared battery was 50mAh and the electrolyte solution was a dioxolane solution in which 1M LiN (CF ₃ SO ₂ ) ₂ dissolved.

The lithium sulfur battery prepared according to Comparative Example 1 was charged and discharged at 0.2 C, and the first discharge curve was shown by symbol A in FIG. 2. As shown in FIG. 2, the discharge capacity of the battery of Comparative Example 1 represented 72% of the theoretical capacity of sulfur as a positive electrode active material.

(Example 1)

The theory was carried out in the same manner as in Comparative Example 1 except that a mixture of 95 wt% of dioxolane solution and 5 wt% of 4-fluorobenzophenone in which 1M LiN (CF ₃ SO ₂ ) ₂ was dissolved was used as an electrolyte solution. A lithium sulfur battery having a capacity of 50 mAh was prepared.

After charging and discharging the lithium sulfur battery of Example 1 to 0.2C, a first discharge curve is shown by a symbol B in FIG. 2. As shown in FIG. 2, a discharge plateau, which is not shown in Comparative Example 1, is formed in the vicinity of 1.5V, which is an effect of reducing Li ₂ S ₂ to Li ₂ S by 4-fluobenzophenone. It can be predicted to occur according to. In addition, the discharge capacity of the lithium sulfur battery of Example 1 represented 84.5% of the theoretical capacity of the battery. As a result, it can be seen that the addition of 4-fluorobenzophenone not only increases the capacity, but also exhibits a higher potential during discharge as compared with Comparative Example 1.

(Example 2)

The theoretical capacity was carried out in the same manner as in Example 1, except that 95% by weight of 1M LiN (CF ₃ SO ₂ ) ₂ solution and 5% by weight of 4-chlorobenzophenone were mixed as an electrolyte solution. This 50mAh lithium sulfur battery was manufactured.

The lithium sulfur battery of Example 2 was charged and discharged at 0.2C, and the first discharge curve was shown by symbol C in FIG. 2. As shown in FIG. 2, a discharge flat portion not shown in Comparative Example 1 was formed at about 1.5 V, which is considered to be due to the effect of reducing Li ₂ S ₂ to Li ₂ S by 4-chlorobenzophenone. In addition, the discharge capacity of Example 2 represented 82.5% of the theoretical capacity of the battery. As a result, it can be seen that the addition of 4-chlorobenzophenone not only increases the capacity but also exhibits a higher potential during discharge as compared with Comparative Example 1.

(Example 3)

Same as Example 1 except that a mixture of 95% by weight of dioxolane solution in which 1M LiN (CF ₃ SO ₂ ) ₂ and 5% by weight of 4,4'-difluorobenzophenone was used as the electrolyte solution. The lithium sulfur battery having a theoretical capacity of 50 mAh was prepared.

The lithium sulfur battery of Example 3 was charged and discharged at 0.2C, and the first discharge curve was shown by symbol D in FIG. 2. As shown in FIG. 2, a discharge flat portion, which was not shown in Comparative Example 1, was formed in the vicinity of 1.5 V, which is due to the effect of reducing Li ₂ S ₂ to Li ₂ S by 4,4′-difluorobenzophenone. It is considered to be. In addition, the discharge capacity of Example 2 represented 82.5% of the theoretical battery capacity. As a result, it can be seen that the addition of 4-chlorobenzophenone not only increases the capacity but also exhibits a higher potential during discharge as compared with Comparative Example 1.

(Example 4)

The theoretical capacity was 50 mAh in the same manner as in Example 1, except that 98% by weight of 1M LiN (CF ₃ SO ₂ ) ₂ dissolved in dioxolane solution and 2% by weight of methyl phenyl ketone were used as the electrolyte solution. Phosphorus lithium sulfur battery was prepared.

As a result of charging and discharging the lithium sulfur battery of Example 4 at 0.2C, it showed 77.5% of the theoretical capacity of the battery. It can be seen that the capacity is increased in comparison with Comparative Example 1.

(Example 5)

The theoretical capacity was 50mAh in the same manner as in Example 1, except that 98% by weight of dioxolane solution in which 1M LiN (CF ₃ SO ₂ ) ₂ was dissolved and 2% by weight of diphenyl sulfone were used as the electrolyte solution. Phosphorus lithium sulfur battery was prepared.

As a result of charging and discharging the lithium sulfur battery of Example 5 at 0.2C, 79.5% of the theoretical capacity of the battery was shown. It can be seen that the capacity is increased in comparison with Comparative Example 1.

(Example 6)

Example 1 except that a mixture of 98% by weight of dioxolane solution and 2% by weight of 2-chloroethyl phenyl sulfone in which 1M LiN (CF ₃ SO ₂ ) ₂ was dissolved was used as the electrolyte solution. A lithium sulfur battery having a capacity of 50 mAh was prepared.

As a result of charging and discharging the lithium sulfur battery of Example 6 at 0.2C, 81% of the theoretical capacity of the battery was shown. It can be seen that the capacity is increased in comparison with Comparative Example 1.

(Example 7)

Except that 98% by weight of dioxolane solution in which 1M LiN (CF ₃ SO ₂ ) ₂ dissolved and 2% by weight of diphenyl phosphone were used as the electrolyte solution, the theoretical capacity was the same as that of Example 1 above. A lithium sulfur battery of 50 mAh was prepared.

As a result of charging and discharging the lithium sulfur battery of Example 7 at 0.2C, it showed 81.7% of the theoretical capacity of the battery. It can be seen that the capacity is increased in comparison with Comparative Example 1.

(Example 8)

Example 1 was carried out in the same manner as in Example 1 except that 98% by weight of dioxolane solution in which 1M LiN (CF ₃ SO ₂ ) ₂ was dissolved and 2% by weight of 2-chloroethyl phenyl phosphone were used as an electrolyte. A lithium sulfur battery having a theoretical capacity of 50 mAh was produced.

As a result of charging and discharging the lithium sulfur battery of Example 8 at 0.2C, it showed 82.3% of the theoretical capacity of the battery. It can be seen that the capacity is increased in comparison with Comparative Example 1.

As described above, the electrolyte solution of the present invention can improve the discharge capacity and discharge potential of the battery.

Claims (16)

An additive selected from the group consisting of the following Chemical Formulas 1 to 4; Non-aqueous organic solvents; And Lithium salt Electrolyte for lithium secondary battery comprising a. [Formula 1]

(In Formula 1, X _{1 To} X _{10 Are} the same or independently from each other H, C _n H _{2n + 1} (n is an integer of 1 to 10), Br, Cl, F, OH, COOH, SO ₃ H, COO ^- a ⁺ M (here, M is Li, Na, K or Cs _{Im), C n F 2n + 1} (n is an integer of 1 to 10), NO ₂ or _{^{NH 3) - M +, SO}} 3. [Formula 2]

(In Formula 2, X _{1 To} X _{5 Are} the same or independently from each other H, C _n H _{2n + 1} (n is an integer of 1 to 10), Br, Cl, F, OH, COOH, SO ₃ H, COO ^- a ⁺ M (here, M is Li, Na, K or Cs _{Im), C n F 2n + 1} (n is an integer of 1 to 10), NO ₂ or _{^{NH 3, - M +, SO}} 3 X ₆ is H, C _n H _{2n + 1} , C _n H _2n OH, C _n H _2n OH, C _n H _2n COOH, C _n H _2n SO ₃ H, C _n H _2n COO ^- M ⁺ , C _n H _2n SO ₃ ^- M ⁺ , where M is Li, Na, K or Cs, C _n F _{2n + 1} , C _n F _2n OH, C _n F _2n COOH, C _n F _2n COO ^- M ⁺ ( here, M is Li, Na, K or Cs), C _n F _2n SO ₃ H or C _n F _2n SO ₃ ^- and M ^+, where n is an integer of 1 to 10). [Formula 3]

(In Formula 3, X _{1 To} X _{10 Are} the same or independently from each other H, C _n H _{2n + 1} (n is an integer of 1 to 10), Br, Cl, F, OH, COOH, SO ₃ H, COO ^{_{- M +, SO 3 - M}} + a (where, M is Li, Na, K or Cs _{Im), C n F 2n + 1} , NO 2 or NH _3). [Formula 4]

(In Formula 4, X _{1 To} X _{5 Are} the same or independently from each other H, C _n H _{2n + 1} (n is an integer of 1 to 10), Br, Cl, F, OH, COOH, SO ₃ H, COO ^- a ⁺ M (here, M is Li, Na, K or Cs _{Im), C n F 2n + 1} , NO 2 or _{^{NH 3, - M +, SO}} 3 X ₆ is H, C _n H _{2n + 1} , C _n H _2n OH, C _n H _2n OH, C _n H _2n COOH, C _n H _2n SO ₃ H, C _n H _2n COO ^- M ⁺ , C _n H _2n SO ₃ ^- M ⁺ , where M is Li, Na, K or Cs, C _n F _{2n +} 1, C _n F _2n OH, C _n F _2n COOH, C _n F _2n COO ^- M ⁺ , where M is Li, Na, K or Cs, C _n F _2n SO ₃ H or C _n F _2n SO ₃ ^- M ⁺ , n is an integer from 1 to 10.) delete delete According to claim 1, wherein the amount of the additive is a lithium secondary battery electrolyte of 0.1 to 10% by weight of the total weight of the electrolyte. The electrolyte of claim 4, wherein the amount of the additive is 1 to 5% by weight of the total weight of the electrolyte. The electrolyte of claim 1, wherein the electrolyte is used in a battery having an operating voltage of 0.8 to 3.0V. The electrolyte for a lithium secondary battery according to claim 6, wherein the battery is a lithium sulfur battery. An electrolyte comprising an additive selected from the group consisting of Formulas 1 to 4, a non-aqueous organic solvent, and a lithium salt; A positive electrode including a positive electrode active material; And A negative electrode containing a negative electrode active material Lithium secondary battery comprising a. [Formula 1]

(In Formula 1, X _{1 To} X _{10 Are} the same or independently from each other H, C _n H _{2n + 1} (n is an integer of 1 to 10), Br, Cl, F, OH, COOH, SO ₃ H, COO ^- a ⁺ M (here, M is Li, Na, K or Cs _{Im), C n F 2n + 1} (n is an integer of 1 to 10), NO ₂ or _{^{NH 3) - M +, SO}} 3. [Formula 2]

(In Formula 2, X _{1 To} X _{5 Are} the same or independently from each other H, C _n H _{2n + 1} (n is an integer of 1 to 10), Br, Cl, F, OH, COOH, SO ₃ H, COO ^- a ⁺ M (here, M is Li, Na, K or Cs _{Im), C n F 2n + 1} (n is an integer of 1 to 10), NO ₂ or _{^{NH 3, - M +, SO}} 3 X ₆ is H, C _n H _{2n + 1} , C _n H _2n OH, C _n H _2n OH, C _n H _2n COOH, C _n H _2n SO ₃ H, C _n H _2n COO ^- M ⁺ , C _n H _2n SO ₃ ^- M ⁺ , where M is Li, Na, K or Cs, C _n F _{2n + 1} , C _n F _2n OH, C _n F _2n COOH, C _n F _2n COO ^- M ⁺ ( here, M is Li, Na, K or Cs integer), C _n F _2n SO ₃ H or C _n F _2n SO ₃ ^- and M ^+, where n is an integer of 1 to 10). [Formula 3]

(In Formula 3, X _{1 To} X _{10 Are} the same or independently from each other H, C _n H _{2n + 1} (n is an integer of 1 to 10), Br, Cl, F, OH, COOH, SO ₃ H, COO ^{_{- M +, SO 3 - M}} + a (where, M is Li, Na, K or Cs _{Im), C n F 2n + 1} , NO 2 or NH _3). [Formula 4]

(In Formula 4, X _{1 To} X _{5 Are} the same or independently from each other H, C _n H _{2n + 1} (n is an integer of 1 to 10), Br, Cl, F, OH, COOH, SO ₃ H, COO ^- a ⁺ M (here, M is Li, Na, K or Cs _{Im), C n F 2n + 1} , NO 2 or _{^{NH 3, - M +, SO}} 3 X ₆ is H, C _n H _{2n + 1} , C _n H _2n OH, C _n H _2n OH, C _n H _2n COOH, C _n H _2n SO ₃ H, C _n H _2n COO ^- M ⁺ , C _n H _2n SO ₃ ^- M ⁺ , where M is Li, Na, K or Cs, C _n F _{2n +} 1, C _n F _2n OH, C _n F _2n COOH, C _n F _2n COO ^- M ⁺ , where M is Li, Na, K or Cs, C _n F _2n SO ₃ H or C _n F _2n SO ₃ ^- M ⁺ , n is an integer from 1 to 10.) delete delete The lithium secondary battery of claim 8, wherein the amount of the additive is 0.1 to 10 wt% of the total weight of the electrolyte. The lithium secondary battery of claim 11, wherein the amount of the additive is 1 to 5 wt% of the total weight of the electrolyte. The lithium secondary battery of claim 8, wherein the lithium secondary battery has an operating voltage of 0.8 to 3.0V. The lithium secondary battery of claim 13, wherein the lithium secondary battery is a lithium sulfur battery. The method of claim 8, wherein the positive electrode active material is inorganic sulfur (elemental sulfur, S ₈ ), Li ₂ S _n (n≥1), polysulfide (Li ₂ S _x , x≥2), disulfide compound, organic sulfur compound, And a sulfur-based compound selected from the group consisting of carbon-sulfur polymers ((C ₂ S _x ) _n : x = 2.5 to 50, n ≧ 2) or mixtures thereof. The method of claim 8, wherein the negative electrode active material is selected from the group consisting of a material capable of reversibly intercalating lithium ions, a material capable of reacting with lithium ions to form a lithium-containing compound reversibly, lithium metal and lithium alloy The lithium secondary battery which becomes.

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