KR100805267B1 - Method for preparing cathode electrode for lithium secondary battery, the cathode electrode prepared by the method and lithium secondary battery comprising the cathode electrode - Google Patents

Abstract

A lithium secondary battery is provided to simplify a conventional coating process for manufacturing a cathode, and to realize excellent cycling stability and structural stability by preventing dissolution of a cathode active material caused by an electrolyte while maintaining the initial capacity. A lithium secondary battery comprises: an anode; a cathode obtained by mixing 100 parts by weight of a lithium transition metal oxide, 5-20 parts by weight of a conductive agent and 3-15 parts by weight of a binder, adding to the resultant mixture 2-4 wt.% of any one compound selected from ZrO2, Al2O3, SiO2, ZnO, TiO2 and SnO2 based on the weight of the lithium transition metal oxide to obtain slurry, and coating a collector with the slurry, followed by drying and rolling; a separator interposed between the anode and the cathode; and an electrolyte containing LiPF6.

Description

Method for preparing a cathode for a lithium secondary battery, a cathode for a lithium secondary battery produced by this and a lithium secondary battery comprising the same {Method for preparing cathode electrode for lithium secondary battery, the cathode electrode prepared by the method and lithium secondary battery comprising the cathode electrode}

1 is an X-ray diffraction pattern graph of LiMn ₂ O ₄ heat-coated with LiMn ₂ O ₄ and ZrO ₂ .

2a to 2c are observed using the Comparative Example 1 pure LiMn ₂ O _4, Comparative Example 2 in the ZrO ₂ is heat treated coated LiMn ₂ O ₄ and Example 1 ZrO ₂ is added to the cathode for producing a slurry of a scanning electron microscope of the One picture.

Figures 3a and 3b is a comparative example pure LiMn ₂ O ₄ and Comparative photographs observed by ZrO ₂ is heat-treated coated LiMn ₂ O ₄ using the transmission electron microscope of the second embodiment of Fig.

4A to 4D are graphs showing charge and discharge characteristics after 1 cycle, 2 cycles, and 50 cycles of batteries according to Example 1 and Comparative Examples 1 to 3;

5A to 5D are graphs showing high temperature charge and discharge characteristics after 1 cycle, 2 cycles, and 30 cycles of batteries according to Example 1 and Comparative Examples 1 to 3;

6 is a graph showing the results of evaluating room temperature cycling stability of the batteries according to Example 1 and Comparative Examples 1 to 3.

7 is a graph showing the results of evaluating the high temperature (55 ° C.) cycling stability of the batteries according to Example 1 and Comparative Examples 1 to 3. FIG.

8 is a schematic cross-sectional view of a lithium secondary battery according to one embodiment of the present invention.

The present invention relates to a method of manufacturing a cathode for a lithium secondary battery, a cathode for a lithium secondary battery manufactured thereby, and a lithium secondary battery comprising the same. More specifically, the manufacturing time is shortened and the manufacturing cost is reduced by simplifying a conventional coating method. Not only can provide a method for manufacturing a cathode for a lithium secondary battery that can be reduced, the lithium secondary battery comprising a lithium secondary battery cathode prepared by the above method does not show a decrease in the initial capacity, the cathode by the electrolyte The present invention relates to a lithium secondary battery cathode and a lithium secondary battery comprising the same, a method for producing a lithium secondary battery cathode having excellent cycling stability and structural stability, which can effectively prevent the dissolution of an active material.

Specifically, the lithium secondary battery includes a cathode / anode active material, a current collector, and an electrolyte solution, and lithium-transition metal oxide is used as the cathode active material, and lithium metal, lithium alloy, carbon (crystalline or amorphous), or carbon is used as the anode active material. A composite material is used, and the current collector is a metal current collector as a passage through which electrons generated and supplied to the active material can move. In addition, the electrolyte serves as a medium for ion conduction, and consists of a non-aqueous solvent, lithium salt, and other additives.

In general, examples of the cathode active material for a lithium secondary battery include lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), lithium manganese oxide (LiMnO ₂ or LiMn ₂ O ₄ ), a composite metal oxide, and the like. Among these, LiCoO ₂ has a good electric conductivity, high battery voltage, and excellent electrode characteristics, so it is currently occupying most of the commercially available cathode active materials for lithium ion batteries. However, since cobalt is a rare metal and expensive, and there is a concern that it may cause environmental problems, development of a low cost and stable cathode material is desired.

For this reason, research on lithium manganese oxide or lithium manganese composite oxide instead of lithium cobalt oxide is continuously conducted. In particular, LiMn ₂ O ₄ has no toxicity, low manufacturing cost, and high cell voltage. Many developments are being made. However, lithium manganese oxide has a problem of poor cycling stability and structural instability in high temperature applications. In particular, lithium manganese oxide has a manganese in the presence of an acidic compound such as HF in the electrolyte at a high temperature of about 40 to 50 ° C. There was a problem that the capacity of the battery is drastically reduced due to the phenomenon that the ion is eluted.

Therefore, in order to improve the problem of eluting the manganese ions, attempts have been made to prevent contact with the electrolyte by coating the surface of lithium manganese oxide with a metal oxide such as ZrO ₂ , Al ₂ O _3, or SiO ₂ . These attempts are performed by applying the colloidal metal oxide to the cathode active material, which can cause an additional reaction because the cathode active material must be impregnated in the colloidal solution, and heat and wait for drying. There was a problem that time and energy was consumed. In addition, there is a problem that the coating layer is difficult to insert and detach the lithium ions from the active material, causing the initial capacity of the battery.

Accordingly, the present invention solves the problems of the prior art, and provides a method for manufacturing a cathode for a lithium secondary battery that can shorten the manufacturing time and reduce the manufacturing cost by simplifying the conventional coating method, and further reduces the initial capacity Without being visible, the present invention provides a lithium secondary battery cathode and a lithium secondary battery including the same, which can effectively prevent the dissolution of the cathode active material by the electrolyte, and thus have excellent cycling stability and structural stability.

The present invention to achieve the first technical problem,

(a) mixing 5 to 20 parts by weight of the conductive material and 3 to 15 parts by weight of the binder with respect to 100 parts by weight of the lithium-transition metal oxide;

(b) preparing a slurry by adding 2 to 4 wt% of any one compound selected from the group consisting of ZrO ₂ , Al ₂ O ₃ , SiO ₂ , ZnO, TiO _2, and SnO ₂ with respect to the lithium-transition metal oxide; step; And

(c) coating, drying and rolling the slurry on a current collector

It provides a method of manufacturing a cathode for a lithium secondary battery comprising a.

According to a preferred embodiment of the present invention, the lithium-transition metal oxide is LiCoO ₂ , LiMnO ₂ , Li _x Mn ₂ O ₄ (x≤1) or Li _x M _y Mn _{2 - y} O ₄ (M = Ti, Fe, Ni, Co, Zn, Al or Mg).

According to another preferred embodiment of the present invention, the conductive material is graphite, carbon black, conductive fibers, metal powder, conductive metal oxide or conductive polymer.

According to another preferred embodiment of the invention, the binder is polyvinylidene fluoride (PVdF), a copolymer of polyhexafluoropropylene-polyvinylidene fluoride (PVdF / HFP), poly (vinylacetate), poly Vinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, alkylated polyethylene oxide, polyvinyl ether, poly (methyl methacrylate), poly (ethyl acrylate), polytetrafluoroethylene (PTFE), polyvinyl chloride, polyacrylic Ronitrile, polyvinylpyridine, styrene-butadiene rubber, acrylonitrile-butadiene rubber, ethylene propylene diene monomer (EPDM) or mixtures thereof.

According to another preferred embodiment of the present invention, the current collector is stainless steel, nickel, aluminum, titanium or alloys thereof, or the surface of the aluminum or stainless steel surface treated with carbon, nickel, titanium or silver.

In addition, the present invention provides a cathode for a lithium secondary battery manufactured according to the manufacturing method in order to achieve the second technical problem.

In addition, the present invention to achieve the third technical problem,

Anode; Cathode; A separator disposed between the anode and the cathode; And in a lithium secondary battery comprising an electrolyte, the cathode provides a lithium secondary battery, characterized in that the cathode for the lithium secondary battery.

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

Unlike the prior art, the method of manufacturing a cathode for a lithium secondary battery according to the present invention is not easy to coat the surface of the cathode active material particles with a metal oxide, but to easily prepare a slurry by uniformly mixing the cathode active material and the metal oxide. There is no problem such as a decrease in initial capacity due to the metal oxide coating film.

That is, as a method for preventing the cathode active material from eluting by an acidic compound such as HF in the electrolyte, a method of modifying the surface of the electrode to form a protective layer or a method of scavenging HF in the electrolyte may be considered. In the prior art, a method for coating the metal oxide by a method such as heat treatment on the cathode active material particles has been proposed as a method for performing the former method, and the method for performing the latter method is an electrolyte solution A method of dissolving a metal oxide has been suggested.

However, in the case of coating the metal oxide by the heat treatment method, the specific surface area of the metal oxide particles is reduced, thereby lowering the activity of the metal oxide with respect to HF in the electrolyte, and the method of dissolving the metal oxide in the electrolyte is also the cathode active material by HF. There is a problem that can not effectively prevent the eluting phenomenon. In particular, the coating of the metal oxide by the heat treatment method requires a separate process and cost, as well as a problem that the resulting coating layer reduces the initial capacity by preventing the removal and insertion of lithium ions.

Therefore, in the present invention, the cathode active material and the metal oxide are uniformly mixed to prepare a slurry. In this case, the elution phenomenon of the cathode active material can be effectively prevented as well as the metal oxide can be effectively prevented without a separate manufacturing process or manufacturing cost. It has been found that the specific surface area of the particles is increased, which is very effective for the collection of HF in the electrolyte.

Lithium-transition metal oxide used in the present invention is not particularly limited as long as it is commonly used in the art, for example, LiCoO ₂ , LiMnO ₂ , Li _x Mn ₂ O ₄ (x≤1) or Li _x M _y Mn _{2 -} a _{y O 4 (M = Ti,} Fe, Ni, Co, Zn, Al , or Mg) may be used.

In addition, the conductive material used in the present invention is not particularly limited as long as it is commonly used in the art, such as artificial graphite or natural graphite, acetylene black, Ketjen black, denka black, thermal black or channel black, etc. Conductive fibers such as carbon black, carbon fiber or metal fiber, aluminum, tin, bismuth, silicon, antimony, nickel, copper, titanium, vanadium, chromium, manganese, iron, cobalt, zinc, molybdenum, tungsten, silver, gold Metal powders such as lanthanum, ruthenium, platinum, iridium or alloys thereof, conductive metal oxides such as titanium oxide, or conductive polymers such as polyaniline, polythiophene, polyacetylene or polypyrrole.

The content of the conductive material is preferably 5 to 20 parts by weight based on the lithium-transition metal oxide. When the content of the conductive material is less than 5 parts by weight, the electrochemical properties of the battery are lowered, and when the content of the conductive material exceeds 20 parts by weight, It is not preferable because there is a problem of lowering the energy density.

In addition, the binder used in the present invention serves to paste the active material, the mutual adhesion of the active material, the adhesion with the current collector, the buffer effect on the expansion and contraction of the active material, for example, polyvinylidene fluoride (PVdF ), Copolymers of polyhexafluoropropylene-polyvinylidene fluoride (PVdF / HFP), poly (vinylacetate), polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, alkylated polyethylene oxide, polyvinyl ether, poly (Methyl methacrylate), poly (ethyl acrylate), polytetrafluoroethylene (PTFE), polyvinylchloride, polyacrylonitrile, polyvinylpyridine, styrene-butadiene rubber, acrylonitrile-butadiene rubber, ethylene propylene Diene monomer (EPDM) or mixtures thereof, but is not necessarily limited thereto.

The content of the binder is preferably 3 to 15 parts by weight with respect to the lithium-transition metal oxide. When the content of the binder is less than 3 parts by weight, there is a problem in that the adhesion between the electrode active material and the current collector is insufficient, and 15 parts by weight. If it exceeds, the adhesion is good, but there is a problem that the battery capacity is lowered because the content of the electrode active material is reduced by that amount is not preferable.

On the other hand, the cathode for producing a slurry used in the present invention 2 to 4% by weight of any one compound selected from the group consisting of Al ₂ O ₃ , SiO ₂ , ZnO, TiO ₂ , and SnO ₂ with respect to the lithium-transition metal oxide It is characterized in that it comprises, but when the content is less than 2% by weight has little effect of the addition, when it exceeds 4% by weight is not preferable because it may adversely affect the capacity of the lithium-transition metal oxide.

Subsequently, the cathode for a lithium secondary battery according to the present invention may be manufactured by coating, drying, and rolling the prepared slurry on a cathode current collector.

As the cathode current collector, a surface treatment of carbon, nickel, titanium or silver on the surface of stainless steel, nickel, aluminum, titanium or alloys thereof, aluminum or stainless steel may be used.

The present invention also provides a cathode for a lithium secondary battery produced by the above method. The cathode for a lithium secondary battery according to the present invention does not generate agglomeration or agglomeration of metal oxide particles, which may be generated when the metal oxide is coated by a conventional heat treatment coating method, and thus, a larger ratio than the conventional cathode. Has a surface area. In addition, the cathode for a lithium secondary battery according to the present invention not only decreases the initial capacity, but also has excellent charge and discharge characteristics and cycling stability.

In addition, the present invention is an anode; Cathode; A separator disposed between the anode and the cathode; And in a lithium secondary battery comprising an electrolyte, the cathode provides a lithium secondary battery, characterized in that the cathode for the lithium secondary battery.

In the lithium secondary battery according to the present invention, the anode may be manufactured by forming an anode active material layer on an anode current collector, and the anode active material is not limited thereto, but may be crystalline carbon, amorphous carbon, carbon composite or carbon fiber. Carbon materials, such as lithium metal or lithium alloys, may be used. The lithium alloy may include an alloy of lithium with metals such as aluminum, aluminum, zinc, bismuth, cadmium, antimony, silicon, lead, tin, gallium, or indium. Can be used.

In addition, as the anode current collector, a surface treated with carbon, nickel, titanium, silver, or the like on the surface of stainless steel, nickel, copper, titanium or alloys thereof, copper or stainless steel may be used, and the cathode current collector and the anode The shape of the current collector may be in the form of a foil, film, sheet, punched, porous body or foam.

The separator serves to prevent a short circuit between the cathode and the anode, and to provide a passage for the movement of lithium ions. Can be used.

The electrolyte may be used alone or in combination of carbonate, ester, ether or ketone, the carbonate is dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, methylethyl carbonate, ethylene carbonate, propylene Carbonate, butylene carbonate, and the like may be used. Examples of the ester may include γ-butyrolactone, n-methyl acetate, n-ethyl acetate, n-propyl acetate, and the like. It may be used, but is not limited thereto.

8 is a schematic cross-sectional view of a rechargeable lithium battery according to one embodiment of the present invention.

Referring to FIG. 8, a lithium secondary battery according to the present invention can contain an electrode assembly 12 composed of a cathode 13, an anode 15, and a separator 14 prepared by the method according to the above, together with an electrolyte. And can be manufactured by sealing the upper end of the can 10 with the can assembly 20. The can assembly 20 includes a cap plate 40, an insulating plate 50, a terminal plate 60, and an electrode terminal 30, and is combined with an insulating case 70 to seal the can 10. Done.

The electrode terminal 30 is inserted into the terminal through-hole 41 formed in the center of the cap plate 40. When the electrode terminal 30 is inserted into the terminal through-hole 41, the tubular gasket 46 is coupled to the outer surface of the electrode terminal 30 and inserted together to insulate the electrode terminal 30 and the cap plate 40. do. After the can assembly 20 is assembled to the upper end of the can 10, the electrolyte is injected through the electrolyte injection hole 42, and the electrolyte injection hole 42 is closed by a stopper 43. The electrode terminal 30 is connected to the negative electrode tab 17 or the positive electrode tab 16 of the negative electrode 15 to act as a negative electrode terminal or a positive electrode terminal.

As described above, the lithium secondary battery of the present invention has been described as an example of a rectangular type secondary battery, but the lithium secondary battery according to the present invention is not limited thereto, and various modifications such as a cylindrical shape or a pouch type are possible.

Hereinafter, the present invention will be described in more detail with reference to preferred examples, but the present invention is not limited thereto.

Example 1 Manufacture of Lithium Secondary Battery According to the Present Invention

LiMn ₂ O ₄ , a cathode active material, was synthesized by the sol-gel method. That is, 0.1 M of (CH ₃ COO) Li.H ₂ O and 0.2 M of Mn (CH ₃ COO) ₂ .4H ₂ O were dissolved in distilled water and acrylic acid was added to the solution to control the reaction kinetics. Remaining water and acrylic acid were removed using a rotary evaporator at 80 ° C. and the product was heated at 600 ° C. for 12 hours. The result was then calcined at 800 ° C. for 24 hours under oxygen flow.

In a mixture of 85 parts by weight of the prepared LiMn ₂ O ₄ , 10 parts by weight of carbon black as a conductive material and 5 parts by weight of polyvinylidene difluoride as a binder (5% by weight in 1-methyl-2-pyrrolidone), Acetone was added to lower the viscosity and then mixed uniformly at 5000 rpm. Subsequently, ZrO ₂ (zirconium (IV) oxide, nanopowder, Aldrich) was added in an amount of 2% by weight relative to LiMn ₂ O _{4 to} prepare a slurry for preparing a cathode.

Next, the slurry was applied to a current collector made of aluminum foil, followed by drying to prepare a cathode. Cathode molding was performed by hot rolling at 110 ° C. and drying in a vacuum oven at 80 ° C. for 24 hours.

Lithium metal was used as an anode, and a polypropylene separator was placed between the cathode and the anode, and then ethylene carbonate / dimethyl carbonate / LiPF ₆ (Merck Battery Grade, EC / DMC = 1). / 1, 1M LiPF ₆ ) The unit cell was prepared using an organic electrolyte.

Comparative Example 1. Fabrication of Lithium Secondary Battery According to the Prior Art (without ZrO ₂ )

A unit cell was manufactured in the same manner as in Example 1, except that ZrO ₂ was not added to the cathode preparation slurry.

Comparative Example 2. Fabrication of Lithium Secondary Battery According to the Prior Art (ZrO ₂ is Heat-treated Coating)

In the preparation of the cathode active material LiMn ₂ O ₄ , after the firing step for 24 hours at 800 ℃, ZrO ₂ (zirconium (IV) oxide, nano powder, Aldrich) of 2% by weight of the LiMn ₂ O ₄ content Then heated at 800 ° C. for 6 hours and then calcined at 800 ° C. for 18 hours.

Subsequently, LiMn ₂ O ₄ coated with ZrO ₂ as a cathode active material was heat-treated as described above, and the unit cell was prepared in the same manner as in Example 1 except that ZrO ₂ was not added to the cathode preparation slurry. Prepared.

Comparative Example 3. Preparation of Lithium Secondary Battery According to the Prior Art (Including ZrO _{2 in} Electrolyte)

A unit cell was manufactured in the same manner as in Comparative Example 1, except that ZrO ₂ (zirconium (IV) oxide, nanopowder, and Aldrich) was added in an amount of 2% by weight relative to LiMn ₂ O _{4 in the} electrolyte. It was.

Evaluation example

Evaluation Example 1. Analysis of X-ray Diffraction Patterns

The X-ray diffraction pattern of LiMn ₂ O ₄ and ZrO ₂ heat-coated LiMn ₂ O ₄ was analyzed, and the results are shown in FIG. 1. Analysis of the X-ray diffraction pattern was performed by a scan range of 10-85 ° (2θ) and D / MAX-IIA under CuKα condition, and the diffraction angle (2θ) from the ZrO ₂ phase was indicated by an asterisk.

Referring to FIG. 1, it can be seen that both kinds of LiMn ₂ O ₄ are well crystallized because they do not show peaks corresponding to the secondary phase. On the other hand, the heat treatment the coated ZrO ₂ LiMn ₂ O ₄ has a small peak ZrO _2, a ZrO ₂ from the peak analysis shows that did not react with LiMn ₂ O _4.

Evaluation Example 2 Electron Microscope Analysis

Comparative Example 1 pure LiMn ₂ O _4, Comparative Example 2 in the ZrO ₂ the LiMn ₂ O ₄ and Example 1 of ZrO ₂ is the addition of a cathode for producing a slurry SEM coating heat treatment (SEM) (Hitachi, S- 4300 ), And the results are shown in FIGS. 2A to 2C.

2A to 2C, it can be seen that the particle distribution of Comparative Example 1 is 100 nm to 0.5 μm. On the other hand, comparing Comparative Example 2 (FIG. 2B) and Example 1 (FIG. 2C), it can be seen that in Comparative Example 2, ZrO ₂ particles are agglomerated by heat treatment to have a reduced specific surface area.

On the other hand, pure water of Comparative Example 1 LiMn ₂ O ₄ and Comparative Example 2 of ZrO _2, the heat treatment the coated LiMn ₂ O ₄ was observed using a transmission electron microscope (TEM) (JEOL, JEM4010) , also to the result 3a And 3b.

3A and 3B, in Comparative Example 2, it can be seen that in the case of Comparative Example 2, ZrO ₂ particles are agglomerated and attached to LiMn ₂ O ₄ , whereby the ZrO ₂ reactivity with HF is present as a slurry of ZrO ₂ It is predicted that it is not good because its specific surface area becomes smaller.

Evaluation Example 3 Charging / Discharging Characteristics

The charge and discharge characteristics of the batteries according to Example 1 and Comparative Examples 1 to 3 after 1 cycle, 2 cycles and 50 cycles were observed, and the results are shown in FIGS. 4A to 4D.

4A to 4D, it can be seen that the initial charging curve is unstable for the battery according to Example 1 (4c) and Comparative Example 3 (4d) to which ZrO ₂ is added, but it is shown in Comparative Example 2 (4b). In the case of the battery according to the present invention, although the initial charging curve is stable even though ZrO ₂ is added. This is considered to be because lithium migration is difficult in the case of a battery in which ZrO ₂ is present in a slurry or an electrolyte solution. However, instability of this charge curve was not observed in the remaining cycles once the lithium migration path was established.

In addition, high temperature charge and discharge characteristics were observed after 1 cycle, 2 cycles, and 30 cycles of the batteries according to Example 1 and Comparative Examples 1 to 3, and the results are shown in FIGS. 5A to 5D. Comparing Example 1 (5c) and Comparative Example 2 (5b), it can be seen that the contact between ZrO ₂ and LiMn ₂ O ₄ and the specific surface area of ZrO ₂ are important factors for determining charge and discharge characteristics.

Evaluation Example 4 Cycling Stability

The room temperature cycling stability of the batteries according to Example 1 and Comparative Examples 1 to 3 was evaluated, and the results are shown in FIG. 6. Cycling stability is expressed as a function of the number of cycling when measured at 1 / 2C speed and two other charge cuts.

Referring to FIG. 6, it can be seen that a capacity decrease of 15% is observed after 50 cycles in the battery according to Comparative Example 1, and a capacity decrease of 8% is observed in the battery according to Example 1. In addition, in general, a battery having a LiMn ₂ O ₄ cathode coated with ZrO ₂ has been reported to have a reduced initial capacity (YM Lin, HC Wu, YC Yen, ZZ Guo, and NL Wu, J. Electrochem). Soc., 152 (2005) A1526-A1532; Z. Zheng, Z. Tang, Z. Zhang, W. Shen, and Y. Lin, Solid State Ionics 148 (2002) 317-321), and in Example 1 Likewise, when ZrO ₂ was added as a slurry, a decrease in initial capacity of such a battery was not observed. This may be because the surface area of the heat treated ZrO ₂ is reduced, and it does not function properly as an HF scavenger.

Meanwhile, the high temperature (55 ° C) cycling stability of the batteries according to Example 1 and Comparative Examples 1 to 3 was evaluated, and the results are shown in FIG. 7. Cycling stability is expressed as a function of the number of cycling when measured at 1 / 2C speed and two other charge cuts.

Referring to FIG. 7, it can be seen that a capacity decrease of 54% is observed after 30 cycles in the battery according to Comparative Example 1, and a 24% capacity decrease is observed in the battery according to Example 1.

According to the present invention, not only can provide a method of manufacturing a cathode for a lithium secondary battery that can reduce the manufacturing time and reduce the manufacturing cost by simplifying the conventional coating method, the cathode for a lithium secondary battery produced by the above method The lithium secondary battery including not only shows a decrease in initial capacity, but also effectively prevents dissolution of the cathode active material by the electrolyte, and thus has excellent cycling stability and structural stability.

Claims (7)

delete delete delete delete delete delete Anode; 5 to 20 parts by weight of the conductive material and 3 to 15 parts by weight of the binder are mixed with respect to 100 parts by weight of the lithium-transition metal oxide, and ZrO ₂ , Al ₂ O ₃ , SiO ₂ , ZnO, TiO _{2 to} the lithium-transition metal oxide. And a cathode prepared by adding 2 to 4 wt% of any one compound selected from the group consisting of SnO ₂ to prepare a slurry, and then coating the slurry on a current collector, drying and rolling; A separator disposed between the anode and the cathode; And A lithium secondary battery comprising an electrolyte containing LiPF ₆ .

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