KR102207523B1 - Lithium secondary battery - Google Patents

Abstract

The present invention is a boron-containing ion conductive material coated anode; Lithium metal cathode; And an ether-based electrolyte, wherein a coating layer of a positive electrode blocks direct contact with the electrolyte, and an ether-based electrolyte is interposed between the positive electrode and the negative electrode to increase the cycle life of the lithium secondary battery due to the growth of lithium dendrites. As it has the effect of preventing reduction, it can be applied in the battery field of electric vehicles where high-capacity, high-power batteries are used.

Description

Lithium secondary battery {LITHIUM SECONDARY BATTERY}

The present invention relates to a lithium secondary battery including a positive electrode coated with a boron-containing ion conductive inorganic material, an ether-based electrolyte, and a lithium metal negative electrode, and more particularly, as the boron compound, Li ₂ B ₄ O ₇ , LiBO ₂ , LiBO ₃ , Li ₃ BO ₃ , Li ₆ B ₄ O ₉ , Li ₃ B ₁₁ O ₁₈ , Li ₃ B ₇ O ₁₂ , Li ₂ B ₈ O ₁₃ and Li ₂ OB ₂ O ₃ -based glass and B ₂ O ₃ It provides a lithium secondary battery with improved cycle life and efficiency, characterized in that any one selected from or a mixture of two or more of them.

As the technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing, and the use of secondary batteries as a power source for electric vehicles (EV) and hybrid electric vehicles (HEV) has recently been realized. Has become. Accordingly, many studies have been conducted on secondary batteries that can meet various needs, and in particular, there is a high demand for lithium secondary batteries having high energy density, high discharge voltage, and output stability.

In particular, lithium secondary batteries used in hybrid electric vehicles have characteristics that can exhibit large output in a short time and can be used for more than 10 years under severe conditions in which charging and discharging by a large current is repeated in a short time. Safety and output characteristics far superior to those of batteries are inevitably required.

Since the conventional lithium secondary battery uses a carbonate-based electrolyte, there is a disadvantage that the cycle life of the battery is significantly reduced due to the growth of lithium dendrites. The cause of this may be a reaction problem between a carbonate-based electrolyte and a lithium metal. To solve this, an ether-based electrolyte that is relatively stable to lithium metal has been proposed.

In the case of an ether-based electrolyte, since it is effective in improving the morphology of lithium metal and the efficiency of the battery, studies are being actively conducted in lithium-sulfur batteries and lithium-air batteries, which are next-generation batteries using lithium metal as a negative electrode.

Despite these advantages, ether-based electrolytes have poor oxidation stability compared to carbonate-based electrolytes, and when a high-voltage positive electrode material is used, the decomposition reaction of the electrolyte quickly occurs on the surface of the positive electrode active material, resulting in poor battery life and output characteristics. there was.

Accordingly, when a high voltage cathode material is applied in a lithium secondary battery, it is difficult to apply an ether-based electrolyte that is stable to lithium metal.

Republic of Korea Patent Publication No. 2015-0074744 (2015.07.02), "Boron compound coated lithium secondary battery positive electrode active material and its manufacturing method"

As the electrolyte for a lithium secondary battery as described above, the ether-based electrolyte has a relatively stable advantage to lithium metal, but has a problem that the stability is lower than that of the carbonate-based electrolyte, and a decomposition reaction of the electrolyte occurs at the high voltage positive electrode.

Accordingly, the present inventors made diligent efforts to improve the performance of the positive electrode of a lithium secondary battery. As a result of coating a boron-containing ion conductive inorganic material on the positive electrode and using an ether-based electrolyte, it is possible to apply a high voltage positive electrode material, so that the cycle life and output of the battery It was confirmed that the properties were improved to complete the present invention.

Accordingly, an object of the present invention is to provide a lithium secondary battery with improved life characteristics of the battery.

In order to achieve the above object, the present invention

anode;

A negative electrode containing lithium metal or lithium alloy; And

In the lithium secondary battery comprising an electrolyte solution interposed between the positive electrode and the negative electrode,

The positive electrode includes a positive electrode active material coated with an ion conductive inorganic material,

The electrolyte solution provides a lithium secondary battery that is an ether electrolyte.

The boron-containing ion-conducting inorganic material provided by the present invention has excellent affinity and wetting for the positive electrode active material, so that a uniform coating layer can be formed compared to other inorganic materials, and the coating layer itself has ionic conductivity. The smooth movement of lithium ions on the surface becomes possible.

Therefore, even if an ion conductive inorganic material is coated on the positive electrode active material, the increase in the resistance of the positive electrode is small, and the coating layer blocks the direct contact between the electrolyte and the positive electrode to inhibit irreversible decomposition of the positive electrode, thereby improving the cycle life and output characteristics of the lithium secondary battery. I can.

1 is a graph showing a discharge capacity effect according to a cycle life of a lithium secondary battery.
2 is a cross-sectional view of a positive electrode active material coated with an ion conductive inorganic material.

Hereinafter, it will be described in detail so that those of ordinary skill in the art may easily implement the present invention. However, the present invention may be implemented in various different forms, and is not limited to this specification.

In order to solve the above problems, the present invention is a lithium secondary battery with improved cycle life and output characteristics,

anode; A negative electrode containing lithium metal or lithium alloy; And an electrolyte solution interposed between the positive electrode and the negative electrode, wherein the positive electrode includes a positive electrode active material coated with an ion conductive inorganic material, and the electrolyte solution is an ether electrolyte.

The term'lithium secondary battery' used in the present invention refers to a battery in which lithium ions existing in an ionic state move from a positive electrode to a negative electrode during discharge and from a negative electrode to a positive electrode during charging to generate electricity.

In the present invention, the positive electrode may include a positive electrode active material coated with an ion conductive inorganic material.

The positive electrode active material may include a complex oxide capable of intercalating and deintercalating lithium ions, and LiCoO ₂ , LiNiO ₂ , Li _{1 + x} Mn _{2 - x} O ₄ (0≦ _x ≦0.33), Li ₂ CuO ₂ , LiV ₃ O ₈ , LiFe ₃ O ₄ , LiNi _{1 -x} M _x O ₂ (M is Co, Mn, Al, Cu, Fe, Mg, B or Ga; 0.01≤x≤0.3), LiMn _{2 -x} M _x O ₂ (M is Co, Ni, Fe, Cr, Zn or Ta; 0.01≤x≤0.1), Li ₂ Mn ₃ MO ₈ (M is Fe, Co, Ni, Cu or Zn), and Li (Ni _{1 -xy} Co _x M _y ) O ₂ (0≤x≤0.33, 0≤y≤0.33, M may include one or more compounds selected from the group consisting of Mn, Al, Mg, or Fe).

The positive active material may have an average particle diameter of 3 µm to 20 µm, and preferably 4 µm to 7 µm.

In addition, as shown in FIG. 2 in the present invention, the positive electrode active material has the composite oxide capable of reversible intercalation and deintercalation of lithium ions as a core, and contains boron coated on the surface of the core. It may include an ion conductive inorganic material.

The boron-containing ion conductive inorganic material provided by the present invention is Li ₂ B ₄ O ₇ , LiBO ₂ , LiBO ₃ , Li ₃ BO ₃ , Li ₆ B ₄ O ₉ , Li ₃ B ₁₁ O ₁₈ , Li ₃ B ₇ O ₁₂ , It may be one or more compounds selected from the group consisting of Li ₂ B ₈ O ₁₃ and Li ₂ OB ₂ O ₃ based glass and B ₂ O ₃ .

In addition, the ion conductive inorganic material is HB(OH) ₂ or H ₃ BO ₃ It may be one or more compounds selected from among.

In this case, the ion conductive inorganic material may have a thickness of 1 nm to 1 μm, preferably 10 nm to 100 nm, on the positive electrode active material. If the thickness of the coating layer is less than the above range, the effect of blocking contact with the electrolyte decreases, and if it exceeds the above range, the interfacial resistance increases and the lithium ion conductivity decreases, causing a problem in the electrode performance. It is preferable to use.

Meanwhile, the positive electrode active material may contain an ion conductive inorganic material in an amount of 1,000 ppm to 10,000 ppm. If it is less than 1,000 ppm, the effect of the boron compound is insufficient, and if it exceeds 10,000 ppm, there is a problem that the complex oxide is excessively coated. The ion conductive inorganic material included in the coating layer of the positive electrode active material may be measured using, for example, ICP mass analysis.

Methods of forming the coating layer on the surface of the positive electrode active material include generally a dry mixing method and a wet mixing method.

The dry mixing method may be performed using a mixing method using a shaker, a mortar grinder mixing method, and a mixing method using a mechanical milling method. Specifically, the mixing method using a shaker may be performed by hand mixing the positive electrode active material and shaking it several times. In addition, the mortar grinder mixing method is a method of uniformly mixing a positive electrode active material and an ion conductive inorganic material using mortar.

In addition, the mechanical milling method includes, for example, a roll-mill, a ball-mill, a high energy ball mill, a planetary mill, a stirred ball mill, By using a vibrating mill or a jet-mill, the positive electrode active material and the ion conductive inorganic material can be mixed by mechanical friction, and for example, it is mechanically compressed by rotating at a rotation speed of 100 rpm to 1000 rpm. Stress can be applied.

In the case of using the wet mixing method according to an embodiment of the present invention, there is an advantage in that the coating layer formed on the surface of the positive electrode active material can be obtained more uniformly than the dry mixing method. As an example of the wet mixing method, after preparing a precursor solution of an ion conductive inorganic substance containing boron, a positive electrode active material is added, the solvent is dried to prepare a positive electrode active material coated with a precursor, and then the precursor coating layer is finally formed through heat treatment. A positive electrode active material coated with an ion conductive inorganic material containing boron may be prepared. Alternatively, a solution is prepared by dissolving the boron-containing ion conductive inorganic substance itself in a non-aqueous organic solvent, and after the positive electrode active material is added, the positive electrode active material coated with the boron-containing ion conductive material is prepared through low heat treatment such as drying the solvent. Method can be used. The above method does not use water as a solvent and uses non-aqueous ethanol as an organic solvent, so when preparing a solution for coating an ion conductive inorganic material, the positive electrode active material is not damaged even if the positive electrode active material is added to the solvent and mixed. There is this. Therefore, it is preferable to use the wet mixing method in consideration of these points.

In the case of the boron-containing ion conductive inorganic material provided in the present invention, it is possible to form a uniform coating layer compared to other inorganic materials because of excellent affinity and wettability for the positive electrode active material, and the positive electrode coating layer containing the ion conductive inorganic material itself Since ions have ion conductivity, there is an advantage in that lithium ions are smoothly moved by increasing the concentration of lithium ions on the surface of the positive electrode active material.

Therefore, even if an ion-conducting inorganic material is coated on the positive electrode, the increase in resistance of the positive electrode is relatively small, and the coating layer blocks direct contact between the positive electrode and the electrolyte to prevent the electrolyte from being irreversibly decomposed on the surface of the positive electrode. Life and lithium efficiency are improved.

The positive electrode according to the present invention prepares a positive electrode composition by adding a conductive material and a binder to a positive electrode active material coated with a boron-containing ion conductive inorganic material, and then diluting it in a predetermined solvent (dispersion medium) to prepare a slurry prepared on the positive electrode current collector. It can be directly coated and dried to form an anode layer. Alternatively, a positive electrode layer may be prepared by casting the slurry on a separate support and then laminating a film obtained by peeling from the support on a positive electrode current collector. In addition to this, the anode may be manufactured in various ways using a method well known to those skilled in the art.

The conducting material serves as a path through which electrons move from the positive electrode current collector to the ion conductive inorganic material, thereby imparting electron conductivity, as well as the lithium ion dissolved in the electrolyte solution by electrically connecting the electrolyte solution and the ion conductive inorganic material. It plays the role of this moving path at the same time.

Therefore, when the amount of the conductive material is insufficient or the role cannot be performed properly, the non-reactive portion of the material in the electrode increases, resulting in a decrease in capacity. In addition, high rate discharge characteristics and charge/discharge cycle life are adversely affected. Therefore, it is necessary to add an appropriate conductive material. The content of the conductive material is preferably added appropriately within the range of 0.01 to 30% by weight based on the total weight of the positive electrode composition.

The conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery, for example, graphite; Carbon blacks such as Denka Black, Acetylene Black, Ketjen Black, Channel Black, Furnace Black, Lamp Black, Summer Black and Super-C; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used. Specific examples of commercially available conductive materials include acetylene black-based Chevron Chemical Company, Denka Singapore Private Limited, Gulf Oil Company, Ketjenblack, and EC-based Armak. Company (Armak Company) product, Vulcan (Vulcan) XC-72 Cabot Company (Cabot Company) product and Super-P (Timcal company product), and the like can be used.

The binder is for adhering the ion conductive inorganic material to the current collector well, it must be well dissolved in a solvent, and must not only form a conductive network between the ion conductive inorganic material and the conductive material well, but also have adequate impregnation of the electrolyte solution.

The binder applicable to the present invention may be any binder known in the art, and specifically, a fluororesin binder containing polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE). ; Rubber binders including styrene-butadiene rubber, acrylonitrile-butadiene rubber, and styrene-isoprene rubber; Cellulose-based binders including carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, and regenerated cellulose; Polyalcohol binder; Polyolefin-based binders including polyethylene and polypropylene; Polyimide-based binder, polyester-based binder, and silane-based binder; may be a mixture or a copolymer selected from the group consisting of, but is not limited thereto.

The content of the binder may be 0.5 to 30% by weight based on the total weight of the positive electrode composition, but is not limited thereto. When the content of the binder resin is less than 0.5% by weight, the physical properties of the positive electrode are deteriorated, so that the ion conductive inorganic material and the conductive material may fall off, and if it exceeds 30% by weight, the ratio of the ion conductive inorganic material and the conductive material in the positive electrode is relatively As a result, the battery capacity may decrease, and the efficiency may decrease by acting as a resistance element.

The positive electrode composition including the ion conductive inorganic material, a conductive material, and a binder may be diluted in a predetermined solvent and coated on the positive electrode current collector using a conventional method known in the art.

First, a positive electrode current collector is prepared. In general, the positive electrode current collector has a thickness of 3 to 500 μm. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes to the battery, for example, stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel. Surface treatment of carbon, nickel, titanium, silver, or the like may be used on the surface of. The current collector may increase the adhesion of ion-conducting inorganic materials by forming fine irregularities on its surface, and various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics are possible.

Next, a positive electrode composition including a positive electrode active material coated with an ion conductive inorganic material, a conductive material, and a binder as described above may be mixed with a predetermined solvent to prepare a slurry. At this time, the solvent should be easy to dry and can dissolve the binder well, but it is most preferable that the ion conductive inorganic material and the conductive material can be maintained in a dispersed state without dissolving.

The solvent (dispersion medium) according to the present invention may be water or an organic solvent, and the organic solvent is N-methylpyrrolidone (NMP), dimethylformamide, isopropyl alcohol or acetonitrile, methanol, ethanol, tetrahydrofuran group An organic solvent containing at least one selected from is applicable.

At this time, the method of applying the slurry is not limited, for example, Doctor blade coating, Dip coating, Gravure coating, Slit die coating, and spin coating. It can be manufactured by performing (Spin coating), comma coating, bar coating, reverse roll coating, screen coating, cap coating method, etc. .

After such a coating process, the evaporation of the solvent (dispersion medium), the denseness of the coating film, and adhesion between the coating film and the current collector are achieved through the drying process. At this time, drying is performed according to a conventional method, and this is not particularly limited.

The lithium secondary battery provided by the present invention may have a structure in which a lithium salt-containing ether electrolyte is impregnated in an electrode assembly having a structure in which a separator is interposed between a positive electrode and a negative electrode.

The negative electrode according to the present invention may include a lithium metal or a lithium alloy. Lithium metal, a lithium metal-based alloy, or a lithium intercalating compound may be used in the negative electrode, but is not necessarily limited to these, and may be used as a negative electrode active material in the art. Anything that can occlude/release lithium is possible. Since the anode active material determines the capacity of the lithium secondary battery, the anode active material may be, for example, lithium metal. The lithium metal-based alloy includes, for example, an alloy of lithium, such as aluminum, tin, magnesium, indium, calcium, titanium, vanadium, and the like. The negative electrode may be a lithium metal sheet as it is used as a negative electrode.

The separator according to the present invention is not particularly limited in its material, and physically separates the anode and the cathode, and has an electrolyte and ion permeability, and can be used without particular limitation as long as it is commonly used as a separator in an electrochemical device. As a porous, non-conductive or insulating material, in particular, it is preferable that the electrolyte has low resistance to ion migration and excellent electrolyte-moisturizing ability. For example, a polyolefin-based porous membrane or a nonwoven fabric may be used, but is not particularly limited thereto.

The thickness of the separator is not particularly limited, but is preferably in the range of 1 to 100 µm, and more preferably in the range of 5 to 50 µm. When the thickness of the separator is less than 1 µm, mechanical properties cannot be maintained, and when the thickness of the separator exceeds 100 µm, the separator acts as a resistive layer, thereby deteriorating battery performance.

The pore size and porosity of the separator are not particularly limited, but the pore size is preferably 0.1 to 50 μm, and the porosity is preferably 10 to 95%. If the pore size of the separator is less than 0.1 μm or the porosity is less than 10%, the separator acts as a resistive layer, and if the pore size exceeds 50 μm or the porosity exceeds 95%, mechanical properties cannot be maintained. .

In general, carbonate-based electrolytes have a high viscosity and low ionic conductivity, and a conventional lithium metal battery to which a carbonate-based electrolyte is applied has a disadvantage in that the cycle life is significantly reduced due to the growth of lithium dendrite. Therefore, the ether-based electrolyte solution provided by the present invention has a relatively small dielectric constant and a relatively high dipole moment compared to a carbonate-based solvent, so that lithium ion mobility and lithium salt dissociation degree can be improved. The battery can exhibit excellent output characteristics.

The ether electrolyte is dibutyl ether, 2-methyl tetrahydrofuran, tetrahydrofuran, dimethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol It may be one or more selected from diethyl ether, and specifically, may be dimethyl ether.

Lithium salt may be included in the ether electrolyte. As the lithium salt, those commonly used in an electrolyte for a lithium secondary battery may be used without limitation. For example, the lithium salt is LiCl, LiBr, LiI, LiNO _{3 ,} LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiPF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, chloro borane lithium, 4 phenyl borate lithium and any one selected from the group consisting of imide, or two or more of these. I can.

The lithium salt may have a concentration of 0.5 to 5M in the ether electrolyte, and preferably may be included in a concentration of 1 to 3M.

The injection of the ether electrolyte may be performed at an appropriate step in the manufacturing process of the electrochemical device according to the manufacturing process and required physical properties of the final product. That is, it can be applied before assembling the electrochemical device or at the final stage of assembling the electrochemical device.

In the lithium secondary battery according to the present invention, in addition to winding, which is a general process, lamination, stacking, and folding processes of a separator and an electrode are possible. In addition, the battery case may be a cylindrical shape, a square shape, a pouch type, or a coin type.

As described above, since the lithium secondary battery according to the present invention stably exhibits excellent discharge capacity, output characteristics and capacity retention rate, portable devices such as mobile phones, notebook computers, and digital cameras, and hybrid electric vehicles (HEVs) ), etc. It is useful in electric vehicle fields.

Accordingly, according to another embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided. The battery module or battery pack may include a power tool; Electric vehicles including electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); Alternatively, it may be used as a power source for any one or more medium and large-sized devices in a power storage system.

Hereinafter, examples will be described in detail to illustrate the present invention in detail. However, the embodiments according to the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the present invention are provided to more completely describe the present invention to those of ordinary skill in the art.

[ Example 1] Manufacture of a lithium secondary battery using a positive electrode active material coated with an ion conductive inorganic material containing boron ( Li ₂ B ₄ O ₇ 4,000ppm)

Li (Ni _0.6 Co _0.2 Mn _0.2 )O ₂ (NMC622) was loaded in a precursor solution of Li ₂ B ₄ O ₇ (a methanol solution in which LiOH and H ₃ BO ₃ were mixed in a ratio of 1:2) at 500°C. By sintering for 5 hours, Li ₂ B ₄ O ₇ was included in an amount of 4,000 ppm to prepare a coated electrode active material.

NMC622 coated with the ion conductive inorganic material Li ₂ B ₄ O ₇ , the conductive material is Super-C, the binder is polyvinylidene fluoride (PVDF), and the ion conductive inorganic material: conductive material: weight ratio of the binder After mixing so as to be 96:2:2, it was dispersed in N-methylpyrrolidone (NMP) to prepare a slurry. The slurry was coated on an aluminum current collector and dried to prepare a positive electrode.

The prepared positive electrode and negative electrode were 20 μm lithium metal (manufactured by Honjo), and the electrolytic solution was prepared as a coin cell by adding 1M LiTFSI and 1wt% LiNO ₃ as a lithium salt to a dimethyl ether electrolytic solution.

[ Example 2] Manufacture of a lithium secondary battery using a positive electrode active material coated with an ion conductive inorganic material containing boron ( Li ₂ B ₄ O ₇ 2,000ppm)

A coin cell was manufactured in the same manner as in Example 1, except that Li ₂ B ₄ O ₇ was included in an amount of 2,000 ppm.

[ Example 3] Manufacture of a lithium secondary battery using a positive electrode active material coated with an ion conductive inorganic material containing boron ( Li ₂ B ₄ O ₇ 1,000ppm)

A coin cell was manufactured in the same manner as in Example 1, except that Li ₂ B ₄ O ₇ was included in an amount of 1,000 ppm.

[ Comparative example 1] Manufacture of lithium secondary battery using positive electrode active material not coated with boron-containing ion conductive inorganic material

A lithium secondary battery was manufactured in the same manner as in Example 1 by using NMC622 not coated with Li ₂ B ₄ O ₇ as a positive electrode active material.

[ Experimental example 1] Measurement of discharge capacity according to cycle

The discharge capacity according to the cycle of the coin cells prepared in Examples 1 to 3 and Comparative Example 1 was measured, and the results are shown in FIG. 1.

Referring to FIG. 1, in the case of the lithium secondary battery containing 4,000 ppm of Li ₂ B ₄ O ₇ in Example 1, the most excellent discharge capacity was 97.72% even after 120 cycles, and Li ₂ B ₄ O ₇ Even in the case of Example 2 containing 2,000 ppm, the discharge capacity of the battery was 97.51%, but in the case of Example 3 containing 1,000 ppm of Li ₂ B ₄ O ₇ , the discharge capacity rapidly decreased from the 75th cycle. It was confirmed that the lower the concentration, the lower the discharge capacity according to the cycle, and the battery of Comparative Example 1 that did not contain Li ₂ B ₄ O ₇ was determined to have exhausted the discharge capacity at the 75th cycle.

Accordingly, it was confirmed that the higher the concentration of Li ₂ B ₄ O ₇ was contained, the better the life characteristics and output characteristics according to the cycle of the lithium secondary battery.

The lithium secondary battery according to the present invention can be applied as a high-voltage cathode material, and thus can be applied as a high-capacity, high-power battery in various technical fields.

100: positive active material
110: coated ion conductive inorganic material
120: composite oxide core

Claims (11)

anode;
A negative electrode made of lithium metal; And
In the lithium secondary battery comprising an electrolyte solution interposed between the positive electrode and the negative electrode,
The positive electrode includes a positive electrode active material coated with an ion conductive inorganic material,
The electrolyte is an ether-based electrolyte,
The ion conductive inorganic material is a lithium secondary battery comprising at least one compound selected from HB(OH) ₂ and H ₃ BO ₃ . The method of claim 1,
The positive electrode active material includes a core including a composite oxide capable of intercalating and desorbing lithium ions; And
Boron-containing ion conductive inorganic material coated on the surface of the core;
Lithium secondary battery comprising a. delete delete The method of claim 1,
The ion conductive inorganic material is a lithium secondary battery coated with a thickness of 1 nm to 1 μm on a positive electrode active material. The method of claim 1,
The positive electrode active material is a lithium secondary battery, characterized in that the ion conductive inorganic material is contained in an amount of 1,000ppm to 10,000ppm. The method of claim 1,
The positive electrode active material is a lithium secondary battery, characterized in that the particles having an average particle diameter in the range of 3 ㎛ to 20 ㎛. The method of claim 2,
The complex oxide is LiCoO ₂ , LiNiO ₂ , Li _{1 + x} Mn _{2 - x} O ₄ (0≤x≤0.33), Li ₂ CuO ₂ , LiV ₃ O ₈ , LiFe ₃ O ₄ , LiNi _{1 - x} M _x O ₂ (M is Co, Mn, Al, Cu, Fe, Mg, B or Ga; 0.01≤x≤0.3), LiMn _{2 - x} M _x O ₂ (M is Co, Ni, Fe, Cr, Zn or Ta And; 0.01≦x≦0.1), Li ₂ Mn ₃ MO ₈ (M is Fe, Co, Ni, Cu, or Zn), and Li(Ni _1-xy Co _x M _y )O ₂ (0≤x≤0.33, 0≤y≤0.33, M is Mn, Al, Mg, or Fe) lithium secondary battery comprising at least one compound selected from the group consisting of. The method of claim 1,
The ether electrolyte is dibutyl ether, 2-methyl tetrahydrofuran, tetrahydrofuran, dimethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol Lithium secondary battery, characterized in that at least one selected from diethyl ether. The method of claim 9,
The ether electrolyte is LiCl, LiBr, LiI, LiNO _{3 ,} LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiPF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, lithium chloroborane, lithium 4 phenyl borate and lithium secondary characterized in that it further comprises at least one lithium salt selected from the group consisting of imide battery. The method of claim 10,
The lithium salt is a lithium secondary battery, characterized in that the concentration of 0.5 to 5M in the ether-based electrolyte.

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