KR20150048499A - Nonaqueous electrolyte and lithium secondary battery containing the same - Google Patents

Abstract

The present invention relates to a non-aqueous electrolyte solution and a lithium secondary battery including the same and, more specifically, a non-aqueous electrolyte solution for a lithium secondary battery, comprising a lithium salt which includes lithuim bis(fluorosulfonyl)imide (LiFSI) which is a first lithium salt and lithium hexafluorophosphate (LiPF_6) which is second lithium salt in mole ratio of 9 to 1 or 1 to 1; and a non-aqueous solvent which includes ethyl propionate, propyl propionate or a propionate based solvent and a carbonate based solvent which are mixtures thereof, and a lithium secondary battery including the same. The non-aqueous electrolyte solution for a lithium secondary battery uses a propionate based solvent which hardly causes a film forming reaction, compared with a carbonate-based solvent, and electrolyte salt which is lithuim bis(fluorosulfonyl)imide (LiFSI) together, thereby improving stability of films in passivity. In addition, the non-aqueous electrolyte solution uses LiPF_6 having enough fluorine as electrolyte salt and accordingly resolves corrosion of current collectors generated when imide-based electrolyte salt is used, thereby improving long-term performance of lithium secondary batteries.

Description

TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte and a lithium secondary battery having the non-aqueous electrolyte,

The present invention relates to a non-aqueous electrolyte and a lithium secondary battery having the non-aqueous electrolyte, and more particularly, to a non-aqueous electrolyte and a lithium secondary battery having the non-aqueous electrolyte that improve the stability of a passive film and improve long-

Recently, interest in energy storage technology is increasing. As the application fields of cell phones, camcorders, notebook PCs and even electric vehicles are expanding, efforts for research and development of electrochemical devices are becoming more and more specified. The electrochemical device is one of the most attracting fields in this respect. Of these, the development of a rechargeable secondary battery has become a focus of attention. In recent years, in order to improve the capacity density and the specific energy, Research and development on the design of electrodes and batteries are underway.

Among the currently applied secondary batteries, the lithium secondary battery developed in the early 1990s has advantages such as higher operating voltage and higher energy density than conventional batteries such as Ni-MH, Ni-Cd and sulfuric acid-lead batteries using an aqueous electrolyte solution .

During the initial charging of the lithium secondary battery, lithium ions from the cathode active material such as lithium metal oxide migrate to the anode active material such as graphite and are inserted between the layers of the anode active material. At this time, the electrolyte and the lithium ion react with each other on the surface of the anode active material to form a SEI (Solid Electrolyte Interface) layer. Among the components of the passive film, it is known that the main components are Li ₂ CO ₃ , Li ₂ O, LiOH, lithium alkoxide, lithium alkyl carbonate, and the like.

The passive film acts as an ion tunnel and allows only lithium ions to pass through. The SEI layer is an effect of such an ion tunnel and prevents an organic solvent molecule having a large molecular weight moving together with lithium ions from being inserted between the layers of the anode active material in the electrolyte solution to destroy the anode structure. Therefore, by preventing contact between the electrolyte solution and the anode active material, decomposition of the electrolyte solution does not occur, and the amount of lithium ions in the electrolyte solution is reversibly maintained, so that stable charge / discharge is maintained.

However, the lithium secondary battery repeatedly shrinks and expands as the charge and discharge progresses, causing a change in the lattice constant of the carbon, and repeatedly destroying and restoring the passive film, thereby preventing the side reaction between the electrolyte and the electrode , The long-term performance of the battery changes depending on how fast the formation of the new film is and how it progresses stably.

Particularly, since the passivation film deteriorates rapidly at high temperature, the thermal stability of the initially formed film plays an important role in the performance of the cell, and the rate of formation of the newly formed film also has an important influence on the cell performance. At this time, the nature of the passive film can be changed by changing the kind of the anion of the lithium salt.

In this respect, various research and development are still required to improve the performance of the passive film.

Accordingly, an object of the present invention is to provide a nonaqueous electrolyte solution and a lithium secondary battery having the nonaqueous electrolyte solution that improve the stability of the passive film and solve corrosion problems of the current collector at the same time, thereby improving the long-

According to an aspect of the present invention, there is provided a lithium secondary battery comprising lithium bisfluorosulfonylimide (LiFSI) as a first lithium salt and lithium hexafluorophosphate (LiPF ₆ ) as a second lithium salt in a ratio of 9: 1 to 1: 1 in molar ratio; And a nonaqueous solvent comprising a propionate-based solvent and a carbonate-based solvent which are ethyl propionate, propyl propionate or a mixture thereof, and a non-aqueous solvent for the lithium secondary battery.

At this time, the lithium salt may include the first lithium salt and the second lithium salt in a molar ratio of 9: 1 to 8: 2.

The sum of the molar concentrations of the first lithium salt and the second lithium salt may be 1.0M.

Meanwhile, the non-aqueous electrolyte may further include 0.1 to 3% by weight of vinylene carbonate (VC) based on the non-aqueous electrolyte.

The carbonate-based solvent may be ethylene carbonate, propylene carbonate, or a mixture thereof.

The weight ratio of the propionate-based solvent to the carbonate-based solvent may be 1: 1 to 7: 3.

According to another aspect of the present invention, there is provided a lithium secondary battery comprising an anode, a cathode, and the above-described non-aqueous electrolyte of the present invention.

Here, the anode may include an anode active material layer containing a lithium metal, a carbon material, a metal compound, or a mixture thereof.

The metal compound is composed of Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, In, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ag, Or a compound containing two or more of these metal elements, or a mixture thereof.

The cathode may include a cathode active material layer containing a lithium-containing oxide.

At this time, may be in the lithium-containing oxide of lithium-containing transition metal oxide, the lithium-containing transition metal oxide is _{Li x CoO 2 (0.5 <x} <1.3), Li x NiO 2 (0.5 <x <1.3), Li x MnO _{2 (0.5 <x <1.3)} , Li x Mn 2 O 4 (0.5 <x <1.3), Li x (Ni a Co b Mn c) O 2 (0.5 <x <1.3, 0 <a <1, 0 < 1, 0 <c <1, a + b + c = 1), Li _x Ni _{1 -y} Co _y O ₂ (0.5 <x <1.3, 0 <y <1), Li _x Co _{1 -y} Mn _{y O 2 (0.5 <x <} 1.3, 0≤y <1), Li x Ni 1 -y Mn y O 2 (0.5 <x <1.3, O≤y <1), Li x (Ni a Co b Mn c ) O ₄ (0.5 <x <1.3, 0 <a <2, 0 <b <2, 0 <c <2, a + b + c = 2), Li _x Mn _{2 -z} Ni _z O ₄ x <1.3, 0 <z < 2), Li x Mn 2 -z Co z O 4 (0.5 <x <1.3, 0 <z <2), Li x CoPO 4 (0.5 <x <1.3) and Li _x FePO ₄ (0.5 < x < 1.3), or a mixture of two or more thereof.

Meanwhile, the lithium secondary battery may be a pouch type lithium secondary battery.

According to one embodiment of the present invention, by using a propionate-based solvent that does not actively cause a film-forming reaction relative to a carbonate-based solvent and an electrolyte salt that is lithium bisfluorosulfonylimide (LiFSI) The stability can be improved.

Further, by using LiPF ₆ having sufficient fluoro (F) as an electrolyte salt, it is possible to solve the corrosion problem of the current collector, which is a disadvantage which may occur when the imide electrolyte salt is used.

Thus, the long-term performance of the lithium secondary battery can be improved.

Hereinafter, the present invention will be described in detail. The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory only and are not restrictive of the invention, It should be understood.

According to one aspect of the present invention, lithium bisfluorosulfonylimide (LiFSI), which is a first lithium salt, and lithium hexafluorophosphate (LiPF ₆ ), which is a second lithium salt, are mixed at a molar ratio of 9: 1 to 1: ; And a nonaqueous solvent comprising a propionate-based solvent and a carbonate-based solvent which are ethyl propionate, propyl propionate or a mixture thereof, and a non-aqueous solvent for the lithium secondary battery.

According to the present invention, the stability of the passive film is improved by using the first lithium salt, which is an excess amount of lithium bifluorosulfonylimide, as the electrolyte salt in which the first lithium salt and the second lithium salt are mixed. Further, the first lithium salt may be used in combination with a propionate-based solvent which does not actively cause a film-forming reaction, particularly, a solvent having a short chain length, such as ethyl propionate or propyl propionate, And further improve the long life performance of the battery.

However, if only the first lithium salt as the imide electrolyte salt is used, there is a disadvantage in that corrosion may occur in the current collector. Therefore, lithium having sufficient fluoro (F) capable of forming a film on the surface of the current collector Hexafluorophosphate is added as a second lithium salt in a small amount as compared with the first lithium salt as described above to compensate for the above disadvantages.

At this time, the lithium salt contains the first lithium salt and the second lithium salt in a molar ratio of 9: 1 to 1: 1, more preferably, in a molar ratio of 9: 1 to 8: 2 .

The sum of the molar concentrations of the first lithium salt and the second lithium salt may be 1.0 M, but is not limited thereto.

Further, the non-aqueous electrolyte may further include 0.1 to 3% by weight of vinylene carbonate (VC) based on the non-aqueous electrolyte. By further including the vinylene carbonate, the passive film formed on the surface of the anode can be more firmly formed.

Meanwhile, the carbonate-based solvent may be ethylene carbonate, propylene carbonate, or a mixture thereof. The non-aqueous solvent may be prepared by mixing the propionate-based solvent and the carbonate-based solvent in a weight ratio of 1: 1 to 7: 3 . When the content of the carbonate-based solvent is greater than that of the propionate-based solvent, the viscosity may become too high and the capacity may be lowered. When the weight ratio of the propionate-based solvent to the carbonate- based solvent exceeds 7: 3, The dissociation degree of the salt may be lowered and the capacity may be lowered or the life of the battery may be lowered.

According to another aspect of the present invention, there is provided a lithium secondary battery comprising an anode, a cathode, and the above-described non-aqueous electrolyte of the present invention.

At this time, although the shape of the lithium secondary battery is not limited, the cylindrical battery using the wrapping type jelly roll is more advantageous in terms of swelling, so even if the non-aqueous electrolyte of the present invention is included, Alternatively, in the case of a pouch type lithium secondary battery including a stack or stack / folding type electrode assembly, a further improved effect can be obtained by using the non-aqueous electrolyte of the present invention.

The lithium secondary battery according to the present invention can be produced by a conventional method known in the art. For example, a porous separator may be inserted between the cathode and the anode, and the nonaqueous electrolyte solution according to the present invention may be added to the separator.

The separator used in one embodiment of the present invention may be any porous substrate commonly used in the art, and may be, for example, a polyolefin porous membrane or a nonwoven fabric, but is not particularly limited thereto .

Examples of the polyolefin-based porous film include polyolefin-based polymers such as polyethylene, polypropylene, polybutylene, and polypentene, such as high-density polyethylene, linear low-density polyethylene, low-density polyethylene and ultra-high molecular weight polyethylene, One membrane can be mentioned.

The nonwoven fabric may include, in addition to the polyolefin nonwoven fabric, for example, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate ), Polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, polyphenylenesulfide, and polyethylene naphthalene, which may be used alone or in combination, And nonwoven fabrics formed by mixing these polymers. The structure of the nonwoven fabric may be a spun bond nonwoven fabric or a meltblown nonwoven fabric composed of long fibers.

The thickness of the porous substrate is not particularly limited, but may be 5 to 50 μm, and the pore size and porosity present in the porous substrate are also not particularly limited, but may be 0.01 to 50 μm and 10 to 95%, respectively.

The anode has a structure in which the anode active material layer including the anode active material and the binder is supported on one or both surfaces of the current collector.

As the anode active material, a lithium metal, a carbonaceous material, a metal compound, or a mixture thereof may be used, in which lithium ions can be occluded and released.

Concretely, as the carbon material, low-crystallinity carbon and high-crystallinity carbon may be used. Examples of the low crystalline carbon include soft carbon and hard carbon. Examples of highly crystalline carbon include natural graphite, Kish graphite, pyrolytic carbon, liquid crystal pitch carbon fiber high temperature sintered carbon such as mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches and petroleum or coal tar pitch derived cokes.

The metal compound may be at least one selected from the group consisting of Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, In, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ag, Of at least one metal element. These metal compounds may be a single substance, an alloy, an oxide (TiO ₂ , SnO ₂ Or the like), a nitride, a sulfide, a boride, an alloy with lithium, or the like, but an alloy with a single substance, an alloy, an oxide, and lithium can be increased in capacity. Among them, it may contain at least one element selected from Si, Ge and Sn, and it may further increase the capacity of the battery including at least one element selected from Si and Sn.

The cathode has a structure in which a cathode active material layer including a cathode active material, a conductive material, and a binder is supported on one surface or both surfaces of the current collector.

As the cathode active material, a lithium-containing oxide may be used, and a lithium-containing transition metal oxide may be preferably used. For example, Li _x CoO ₂ (0.5 <x <1.3), Li _x NiO ₂ ), Li _x MnO ₂ (0.5 <x <1.3), Li _x Mn ₂ O ₄ (0.5 <x <1.3), Li _x (Ni _a Co _b Mn _c ) O ₂ Li _x Ni _{1- y} Co _y O ₂ (0.5 <x <1.3, 0 <y <1), Li _{x Co 1 -y Mn y O 2 (} 0.5 <x <1.3, 0≤y <1), Li x Ni 1 -y Mn y O 2 (0.5 <x <1.3, O≤y <1), Li x (Ni _a Co _b Mn _c O ₄ (0.5 <x <1.3, 0 <a <2, 0 <b <2, 0 <c <2, a + b + c = 2), Li _x Mn _{2 -z} Ni _{z O 4 (0.5 <x <1.3} , 0 <z <2), Li x Mn 2 -z Co z O 4 (0.5 <x <1.3, 0 <z <2), Li x CoPO 4 (0.5 <x <1.3 ) And Li _x FePO ₄ (0.5 < x < 1.3), or a mixture of two or more thereof. The lithium-containing transition metal oxide may be coated with a metal such as aluminum (Al) or a metal oxide. In addition to the lithium-containing transition metal oxide, sulfide, selenide and halide may also be used.

The conductive material is not particularly limited as long as it is an electron conductive material that does not cause a chemical change in an electrochemical device. In general, carbon black, graphite, carbon fiber, carbon nanotube, metal powder, conductive metal oxide, organic conductive material and the like can be used. Commercially available products as the conductive material include acetylene black series (manufactured by Chevron Chemical Co., (Chevron Chemical Company or Gulf Oil Company products), Ketjen Black EC series (Armak Company), Vulcan XC-72 (Cabot Company) and Super P (MM (MMM)). For example, acetylene black, carbon black and graphite.

The binder used for the cathode and the anode has a function of holding the cathode active material and the anode active material in the current collector and also connecting the active materials, and a commonly used binder may be used without limitation.

For example, it is possible to use vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, styrene Various types of binder polymers such as styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), and the like can be used.

The current collector used for the cathode and the anode may be any metal having a high conductivity and a metal which can easily adhere to the slurry of the active material and is not reactive in the voltage range of the battery. Specifically, examples of the current collector for a cathode include aluminum, nickel, or a combination thereof. Examples of the current collector for an anode include copper, gold, nickel, or a copper alloy or a combination thereof And the like. In addition, the current collector may be used by laminating the substrates made of the above materials.

The cathode and the anode are kneaded using an active material, a conductive material, a binder, and a high boiling point solvent to form an electrode mixture, and then the mixture is coated on a copper foil or the like of a current collector, dried, Lt; 0 &gt; C for 2 hours under vacuum.

The thickness of the active material layer of the cathode may be 30 to 120 占 퐉 or 50 to 100 占 퐉 and the thickness of the active material layer of the anode may be 1 to 100 占 퐉 or 3 to 70 占 퐉 have. When the cathode and the anode satisfy this thickness range, the amount of active material in each electrode active material layer is sufficiently secured, the battery capacity can be prevented from being reduced, and the cycle characteristics and rate characteristics can be improved.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention.

Example  One

(1) Preparation of non-aqueous electrolyte

A mixed solvent was prepared in a weight ratio of ethylene carbonate (EC): propylene carbonate (PC): ethyl propionate (EP) = 3: 1: 6 and lithium bisfluorosulfonyl imide (LiFSI ) Is 0.9 M, and lithium hexafluorophosphate (LiPF ₆ ) is 0.1 M. Thereafter, vinylene carbonate (VC) was added in an amount of 2% by weight to prepare a nonaqueous electrolytic solution.

(2) Cathode  Produce

LiCoO ₂ cathode active material was prepared. Thereafter, a slurry was prepared by mixing the cathode active material: conductive material: binder in a weight ratio of 96: 2: 2, coating the aluminum (Al) foil current collector by a conventional method, and drying to prepare a cathode.

(3) Anode  Produce

An anode active material slurry was prepared by mixing artificial graphite: SBR binder: thickener in a weight ratio of 98: 1: 1, and then coated on a copper (Cu) foil current collector by a conventional method to prepare an anode.

(4) Production of lithium secondary battery

A pouch type lithium secondary battery was manufactured by charging a stacked electrode assembly formed by interposing a polyethylene porous film between the cathode and the anode, into the pouch-shaped battery case, and injecting the prepared non-aqueous electrolyte.

Example  2

A pouch type lithium secondary battery (1) was produced in the same manner as in Example 1, except that in the preparation of the non-aqueous electrolyte solution of Example 1, propyl propionate (PP) was used instead of ethyl propionate (EP) .

Example  3

(1) In the preparation of the nonaqueous electrolytic solution of Example 1, except for adding 0.8 M of lithium bisfluorosulfonyl imide (LiFSI) and 0.2 M of lithium hexafluorophosphate (LiPF ₆ ) as a lithium salt , A pouch type lithium secondary battery was produced in the same manner as in Example 1.

Comparative Example  One

A pouch type lithium secondary battery was produced in the same manner as in Example 1, except that (1) the non-aqueous electrolyte solution of Example 1 was used so that lithium hexafluorophosphate (LiPF ₆ ) .

Comparative Example  2

(1) In the preparation of the nonaqueous electrolytic solution of Example 1, except for adding 0.3 M of lithium bisfluorosulfonyl imide (LiFSI) and 0.7 M of lithium hexafluorophosphate (LiPF ₆ ) as the lithium salt , A pouch type lithium secondary battery was produced in the same manner as in Example 1.

Comparative Example  3

The same procedure as in Example 1 was carried out except that in the preparation of the nonaqueous electrolytic solution of Example 1 (1), γ-butyrolactone (GBL) was used instead of ethyl propionate (EP) A battery was prepared.

Comparative Example  4

The same procedure as in Example 1 was carried out except that methyl propionate (MP) instead of ethyl propionate (EP) was used in the same weight ratio in the production of the non-aqueous electrolyte solution of Example 1 (1) .

Comparative Example  5

(1) In the preparation of the nonaqueous electrolytic solution of Example 1, lithium hexafluorophosphate (LiPF ₆ ) was added so as to be 1.0 M as a lithium salt, and propyl propionate (PP) was used instead of ethyl propionate A pouch-type lithium secondary battery was produced in the same manner as in Example 1, except that the weight ratio was the same.

The types and contents of the lithium salt and the non-aqueous solvent included in the non-aqueous electrolytes of Examples 1 to 3 and Comparative Examples 1 to 5 were summarized in Table 1 below.

Kinds Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 LiFSI 0.9 M 0.9 M 0.8 M - 0.3 M 0.9 M 0.9 M - LiPF ₆ 0.1 M 0.1 M 0.2 M 1.0 M 0.7 M 0.1 M 0.1 M 1.0 M EC 3 3 3 3 3 3 3 3 PC One One One One One One One One PP - 6 - - - - - 6 EP 6 - 6 6 6 - - - MP - - - - - - 6 - GBL - - - - - 6 - - DEC - - - - - - - - VC 2 wt% 2 wt% 2 wt% 2 wt% 2 wt% 2 wt% 2 wt% 2 wt%

Evaluation of long-term performance of lithium secondary battery

(A) charging at a constant current / constant voltage of 1 C rate and discharging at a constant current of 1 C under the conditions of (A) 25 ° C were performed for 340 cycles (B) Charge of constant current / constant voltage of 1C rate and discharge of 1C constant current method were performed for 300 cycles under the condition of (B) 45 ° C, and the capacity retention ratio was measured. The results are shown in Table 2 below.

Kinds Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 (A) 92% 93% 90% 59% 72% 83% 80% 87% (B) 89% 93% 86% 50%
(The 219th cycle) 76% 81% 78% 86%

As can be seen from Table 2, it can be seen that the capacity retention ratios of Examples 1 to 3 were the most excellent.

Particularly, the non-aqueous solvent was the same as that in Example 1 except that lithium bisfluorosulfonylimide (LiFSI) was not included as the lithium salt but lithium hexafluorophosphate (LiPF ₆ ) was added to 1.0 M, 1, the capacity retention rate is remarkably low. It can be deduced that the lithium bisfluorosulfonyl imide (LiFSI) is not included and the stability of the passive film is deteriorated.

It is also understood that the capacity retention rate is lower than that in the case of Example 1, even in the case of Comparative Example 2 using an excessive amount of lithium hexafluorophosphate (LiPF ₆ ).

In the case of Comparative Example 3 using gamma butyrolactone instead of ethyl propionate (EP) as the non-aqueous solvent and Comparative Example 4 using methyl propionate (MP) instead of ethyl propionate (EP), other conditions The same as Example 1, but the capacity retention rate was lower than that of Example 1.

That is, even if the first lithium salt and the second lithium salt are contained in the same ratio as in the present invention, if the kind of the non-aqueous solvent is different from the non-aqueous solvent of the present invention, the effect of improving the capacity retention rate according to the present invention can not be achieved .

It should be noted that the embodiments of the present invention disclosed herein are merely examples of specific examples for the purpose of understanding and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

Claims (13)

A lithium salt comprising lithium bisfluorosulfonyl imide (LiFSI) as a first lithium salt and lithium hexafluorophosphate (LiPF ₆ ) as a second lithium salt in a molar ratio of 9: 1 to 1: 1; And
And a non-aqueous solvent containing a propionate-based solvent and a carbonate-based solvent which are ethyl propionate, propyl propionate or a mixture thereof. The method according to claim 1,
Wherein the lithium salt comprises the first lithium salt and the second lithium salt in a molar ratio of 9: 1 to 8: 2. The method according to claim 1,
Wherein the sum of the molar concentrations of the first lithium salt and the second lithium salt is 1.0 M. The method according to claim 1,
Wherein the non-aqueous electrolyte further comprises 0.1 to 3% by weight of vinylene carbonate (VC) based on the non-aqueous electrolyte. The method according to claim 1,
Wherein the carbonate-based solvent is ethylene carbonate, propylene carbonate, or a mixture thereof. The method according to claim 1,
Wherein the weight ratio of the propionate-based solvent to the carbonate-based solvent is 1: 1 to 7: 3. A lithium secondary battery comprising an anode, a cathode, and a non-aqueous electrolyte,
The non-aqueous electrolyte according to any one of claims 1 to 6, which is a non-aqueous electrolyte. 8. The method of claim 7,
Wherein the anode comprises an anode active material layer comprising a lithium metal, a carbon material, a metal compound, or a mixture thereof. 9. The method of claim 8,
Wherein the metal compound is selected from the group consisting of Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, In, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ag, A compound containing any one or two or more metal elements selected from the above, or a mixture thereof. 8. The method of claim 7,
Wherein the cathode comprises a cathode active material layer containing a lithium-containing oxide. 11. The method of claim 10,
Wherein the lithium-containing oxide is a lithium-containing transition metal oxide. 12. The method of claim 11,
The lithium-containing transition metal oxide is _{Li x CoO 2 (0.5 <x} <1.3), Li x NiO 2 (0.5 <x <1.3), Li x MnO 2 (0.5 <x <1.3), Li x Mn 2 O 4 ( 0.5 <x <1.3), Li x (Ni a Co b Mn c) O 2 (0.5 <x <1.3, 0 <a <1, 0 <b <1, 0 <c <1, a + b + c = 1), Li _x Ni _{1 -y} Co _y O ₂ (0.5 <x <1.3, 0 <y <1), Li _x Co _{1 -y} Mn _y O _{2 , Li x Ni 1 -y Mn y} O 2 (0.5 <x <1.3, O≤y <1), Li x (Ni a Co b Mn c) O 4 (0.5 <x <1.3, 0 <a <2, 2, 0 <c <2, a + b + c = 2), Li _x Mn _{2 -z} Ni _z O ₄ (0.5 <x <1.3, 0 <z <2), Li _x Mn _{2 - z Co z O 4 (0.5 <} x <1.3, 0 <z <2), Li x CoPO 4 (0.5 <x <1.3) and Li _x FePO ₄ one selected from the group consisting of (0.5 <x <1.3) Or a mixture of two or more thereof. 8. The method of claim 7,
Wherein the lithium secondary battery is a pouch type lithium secondary battery.