KR20190085569A - Method for coating a lithium secondary battery electrode, and lithium secondary battery comprising a electrode using the same - Google Patents

Abstract

The present invention provides a method for coating a lithium secondary battery electrode for forming a ceramic layer on an electrode surface by using an electrode coating solution in which a ceramic compound is dispersed, and a lithium secondary battery enhanced in thermal and mechanical properties by comprising the manufactured lithium secondary battery electrode having a ceramic layer formed on a surface thereof. The battery comprising the electrode having the ceramic coating layer formed on the electrode surface can maintain or enhance charge/discharge characteristics such as capacity retention rate and stability.

Description

TECHNICAL FIELD The present invention relates to a lithium secondary battery electrode coating method, and a lithium secondary battery including the electrode,

The present invention relates to a lithium secondary battery electrode coating method and a lithium secondary battery including the electrode thus prepared. More particularly, the present invention relates to a lithium secondary battery comprising a ceramic secondary battery, A battery electrode coating method, and a lithium secondary battery electrode having a ceramic layer formed on the surface thereof, thereby improving the thermal and mechanical properties.

Recently, lithium secondary batteries having high energy density, operating voltage, and low self-discharge characteristics have been widely used as a demand for small secondary batteries for electronic devices such as notebook computers and mobile phones, as well as demand for mid- to large- .

The lithium secondary battery is composed of an anode and a cathode capable of inserting and separating lithium ions, an organic electrolyte for conducting lithium ions and a separator for safety of the battery, and generates energy by the oxidation / reduction reaction do.

As the cathode active material, a layered lithium transition metal oxide such as LiCoO ₂ is mainly used. Spinel type materials such as LiMn ₂ O ₄ and olivine type materials such as LiFePO ₄ are also used in some cases. However, complicated manufacturing process and capacity characteristics are not preferable to layered lithium transition metal oxide, have.

As the negative electrode active material, a carbon-based material including graphite having a layered structure is mainly used. However, as the demand for medium and large-sized energy storage devices has increased recently, commercialization of metal oxides such as Al ₂ O ₃ , SnO ₂ and SiO ₂ has been researched and developed. However, in the case of the metal oxide, there is a disadvantage that the volume is changed during charging / discharging of the battery, and the life is shortened.

In addition, since the currently used lithium secondary battery uses an organic electrolytic solution, there is a disadvantage that an SEI (Solid Electrolyte Interphase) thin film is formed on the surface of the active material and the electrolyte becomes depleted as the charge and discharge are repeated. In order to prevent such a phenomenon, research and development of a process capable of improving the lifetime characteristics of a battery by uniformly coating a metal oxide on the surface of the electrode active material have been carried out.

In addition, there is a problem that the secondary battery is exposed to ignition because the electrode surface coating technology for preventing ignition is not present in the commercial process at present.

Therefore, there is an urgent need to develop a new lithium secondary battery electrode coating method to solve such a problem.

The present invention provides a lithium secondary battery having improved thermal and mechanical properties by providing a lithium secondary battery electrode coating method using an electrode coating agent in which a ceramic compound is dispersed in a solvent.

According to an aspect of the present invention, there is provided a lithium secondary battery comprising a lithium secondary battery electrode coating including a step of dipping a cathode, an anode, or both in a solution in which a ceramic compound is dispersed, ≪ / RTI >

The present invention also provides a method of manufacturing a lithium secondary battery, comprising the steps of: preparing a positive electrode, a negative electrode, or both; Separation membrane; And a lithium salt-containing non-aqueous electrolytic solution.

Hereinafter, the present invention will be described in detail.

In order to solve the above-mentioned problems, the present invention is characterized in that a ceramic layer is formed on the electrode surface by immersing the cathode, the anode, or both in a solution in which the ceramic compound is dispersed and drying the solution.

In the case of a conventional lithium secondary battery using a metal oxide such as Al ₂ O ₃ , SnO ₂ , or SiO ₂ and using an organic electrolytic solution, there is a disadvantage in that the volume is changed during charging / discharging of the battery. As a result of intensive efforts to solve such problems, the present inventors have found that when a positive electrode or a negative electrode is immersed in a solution in which a ceramic compound is dispersed and then dried to form a ceramic layer on the surface thereof and then applied to a battery, And safety was improved. The present invention is based on this.

The solution in which the ceramic compound is dispersed is a solution in which the ceramic compound is dispersed in a solvent, and the ceramic compound may be a compound having little reactivity with lithium without electrical conductivity. Specifically, SiO ₂ , Al ₂ O ₃ , ZrO ₂ , and M- (OR) _n (M represents Al, Na, Li, Ca, Sr, Ba, Zr, Hf, La, Y, Ge, Sc, Sm, Nb, Yb, Pr, Gd, K, Sn, Ta, In and Mg, R is a hydrocarbon having 2 to 6 carbon atoms and n is 2 to 4. Metal cationic complexes, and combinations thereof.

Preferably, the ceramic compound is selected from the group consisting of M- (OR) _n (M is Al, Na, Li, Ca, Sr, Ba, Zr, Hf, La, Y, Ge, Sc, Sb, Sm, , Gd, K, Sn, Ta, In and Mg, R is a hydrocarbon having 2 to 6 carbon atoms, and n is 2 to 4). Or a combination thereof.

Specifically, the M- (OR) _n may be represented by the following formula:

(M is at least one element selected from the group consisting of Al, Na, Li, Ca, Sr, Ba, Zr, Hf, La, Y, Ge, Sc, Sb, Sm, Nb, Yb, Pr, Gd, K, Sn, , R is a hydrocarbon having 2 to 6 carbon atoms, and n is 2 to 4)

The range of the oxidation number of the metal cation in the metal cation complex, M- (OR) _n , is not particularly limited, but is preferably a transition metal forming a complex with a hydrocarbon oxide, for example, an alkoxide, preferably Al, Na, A transition metal selected from the group consisting of Ba, Zr, Hf, La, Y, Ge, Sc, Sb, Sm, Nb, Yb, Pr, Gd, K, Sn, Ta, In and Mg.

Also, R of the alkoxide (RO-) which forms a complex with the metal cation in the solution may be an alkyl group having 2 to 6 carbon atoms, preferably 2 to 5 carbon atoms, and most preferably 3 to 4 carbon atoms.

In a preferred embodiment, when the anode, the cathode, or both are immersed in a coating solution in which a complex of a metal cation and an alkoxide is dispersed, the metal cation remains thermodynamically stable while the alkoxide is exposed to the air in which steam is present, It is reduced to alcohol and evaporated. Instead, the metal cations are supplied with oxygen from H ₂ O to form metal oxides, thereby forming a coating layer of a stable ceramic compound on the electrode coating surface.

As the solvent for dispersing the ceramic compound, any solvent capable of dispersing the ceramic compound can be used without limitation, and isopropanol can be preferably used.

The solution in which the ceramic compound is dispersed in a solvent is referred to as a ceramic coating solution or a ceramic coating solution in the present invention.

The ceramic coating solution may be a metal precursor solution, particularly a transition metal solution that complexes with hydrocarbon oxides.

In a preferred embodiment, a lithium secondary battery electrode having excellent electrochemical characteristics can be manufactured by immersing the electrode in a solution of the metal precursor represented by M- (OR) _n and drying to coat the electrode.

Preferably, the metal precursor is zirconium (IV) isopropoxide, zirconium (IV) isobutoxide, and the like.

The ceramic coating solution may contain a separate binder if necessary.

When the electrode is immersed in the coating solution of the coating solution according to the present invention and then heat-treated or naturally dried, the metal precursor is oxidized so that a ceramic coating layer is formed on the surface, and the coagulated ceramic coating layer is oxidized So that the performance of the electrode can be improved.

In the present invention, the positive electrode may be formed of a positive electrode active material layer on a positive electrode current collector, and the positive electrode active material layer may be composed of a positive electrode active material composition including a positive electrode active material, a conductive material, a binder and optionally a solvent, Or in the form of a slurry which is dissolved or dispersed in a solvent.

The positive electrode active material can reversibly intercalate / de-intercalate lithium ions (Li ⁺ ) and can be used as long as it is commonly used in the related art. For example, the cathode active material may be LiCoO ₂ , LiNiO ₂ , Li (NiaCobAlc) O ₂ , Li (NiaCobMnc) O ₂ where 0 <a <1, 0 <b <1, 0 <c < (0??? 1) or Li ₂ -βMA? / 3MnO ₃ (0??? 3/2), which is another layered material group such as Li _{2 -?} MA? / 2MnO ₃ ) or _{Li 2 -γMAγ / 4MnO 3 (0≤γ≤2} ) olivine (Oilvine -rich the lithium electrode, such as LiMnO _2, LiMn ₂ O ₄ of spinel, etc. (spinel) structural material, LiFePO _4, which is represented by) the structure Materials, and the like.

The conductive material may be graphite such as natural graphite or artificial graphite, which does not cause chemical change in the battery, and which has good electrical conductivity. Carbon-based materials such as carbon black, acetylene black, and ketjen black; A conductive material such as conductive fibers such as carbon fiber and metal fiber, and the like, and may be contained in an amount of 0.5 to 10 wt% of the total weight of the mixture containing the cathode active material.

The binder is not particularly limited as long as it is a component that assists in bonding between the active material and the conductive material and bonding to the current collector. Examples of the binder include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, alginate , Hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, styrene butadiene rubber, fluorine rubber, and various copolymers. As described above, the binder may be typically contained in an amount of 0.5 to 10 wt% of the total weight of the mixture including the cathode active material.

As the solvent, N-methyl-2-pyrrolidone (NMP), acetone, water and the like can be used. The content of the solvent is usually 1 to 100 wt% of the total weight of the mixture including the cathode active material.

The positive electrode active material composition may be coated on the positive electrode current collector, followed by drying and rolling to produce a positive electrode plate in the form of a film or a thin film on which the positive electrode active material layer is formed. The physical properties of the constituent components of the positive electrode plate produced in the present invention, specifically, the particle diameter (D50), the specific surface area and the like are average values unless otherwise specified.

The cathode current collector is not particularly limited as long as it has conductivity and does not cause chemical change in the battery. For example, stainless steel, copper, nickel, titanium, sintered carbon or aluminum or stainless steel may be used. , Nickel, titanium, silver, or the like may be used.

In the present invention, the negative electrode is a negative electrode active material layer formed on the negative electrode current collector, and the negative electrode active material layer may be composed of a negative electrode active material composition further comprising a negative electrode active material, a conductive material, a binder and optionally a solvent, Or in the form of a slurry which is dissolved or dispersed in a solvent.

The negative electrode active material may be any carbonaceous material that can reversibly intercalate / deintercalate lithium ions (Li ⁺ ) as well as the positive electrode active material, as long as it is commonly used in the related art. For example, the negative electrode active material is crystalline carbon, amorphous carbon, or a mixture thereof. Examples of the crystalline carbon include amorphous, flaky, flake, spherical or fibrous natural graphite; Or artificial graphite. Examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, fired coke, and the like. In addition to carbon-based materials, alloys based on silicon, tin, magnesium, zinc, aluminum and lithium metals can also be applied as anode active materials.

As the conductive material, the binder, the current collector and the solvent in the negative electrode active material composition, the same materials as those of the above-mentioned positive electrode active material composition may be used.

According to the present invention, when an electrode coated with a ceramic compound is applied to a lithium secondary battery, the electrochemical characteristics, particularly the life characteristics of the electrode, can be maintained or improved (see Tables 5 and 6).

FIG. 1 is a view illustrating a method of coating an electrode of a lithium secondary battery according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a method of coating an electrode made of an electrode active material, a binder, .

1 and 2, a method of coating an electrode of a lithium secondary battery according to the present invention includes the steps of immersing an electrode active material, an electrode including a conductive material, a binder, and a current collector in a solution in which a ceramic compound is dispersed, A ceramic oxide layer is formed on the surface. Referring to FIG. 4, according to the present invention, after a metal ion forming a complex with an alkoxide is coated on an electrode, natural oxidation and drying proceeds according to reaction with water vapor in the air, and the oxidized electrode is thermodynamically stable And the contact angle is reduced. Therefore, it is possible to coat a chemically stable oxide layer even if surface treatment is performed directly on the electrode without performing surface treatment on the active material like a conventional process, and a stable oxide layer formed on the electrode surface maintains or improves the lifetime characteristics of the electrode.

According to another aspect of the present invention, there is provided a lithium secondary battery comprising: a positive electrode, a negative electrode, or both having a ceramic layer formed on an electrode surface according to the method of coating an electrode of the lithium secondary battery; Separation membrane; And a lithium salt-containing non-aqueous electrolytic solution.

The separation membrane is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength can be used. The separation membrane may be, for example, an olefin-based polymer such as polypropylene, which is chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene, or the like can be used. The pore diameter of the separator is generally 0.01 to 10 mu m, and the thickness may be generally 5 to 300 mu m.

The lithium salt-containing nonaqueous electrolyte solution is composed of an organic solvent and a lithium salt. As the organic solvent, a nonaqueous liquid organic solvent or an organic solid electrolyte may be used.

Examples of the non-aqueous liquid organic solvent include N-methyl-2-pyrrolidone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, Dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, methyl ethyl ketone, methyl ethyl ketone, methyl ethyl ketone, methyl isobutyl ketone, dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, , Trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane trimethacrylate, Ethylenic organic solvents such as ethyl acetate may be used.

Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, Polymers containing ionic dissociation groups, and the like can be used.

The lithium salt is a material that is readily soluble in the organic solvent, for example, LiCl, LiBr, LiI, LiClO 4, LiBF 4, LiB10Cl 10, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, chloroborane lithium, lower aliphatic carboxylate lithium, and 4-phenylborate lithium imide.

For the purpose of improving the charge-discharge characteristics and the flame retardancy, the electrolytic solution may contain at least one selected from the group consisting of pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride and the like may be added have. In some cases, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart nonflammability, or carbon dioxide gas may be further added to improve high-temperature storage characteristics.

The electrode coating method according to the present invention can improve the lifetime characteristics and safety of the battery after the ceramic coating. In particular, the present invention forms a ceramic coating layer by immersing electrodes in a coating solution in which metal cations are dissolved, and then oxidizing and drying the electrodes. Thus, electrodes can be coated by a simple process without additional post-treatment, It is possible to increase productivity by providing an electrode coating method that can be used. In addition, the thermal and mechanical properties of the battery can be maintained or improved owing to the ceramic coating layer, which is agglomerated by the oxidation process, as well as contributing to safety enhancement.

1 is a diagram illustrating a method of coating a lithium secondary battery electrode according to an embodiment of the present invention.
2 is a schematic view of a case where a ceramic coating is applied to an electrode made of an electrode active material, a binder, and a conductive material according to an embodiment of the present invention.
Fig. 3 is a photograph of the electrode surface before and after the ceramics coating is applied to the electrode according to Fig.
4 is a result of measuring a contact angle with respect to the positive electrode (LiCoO ₂₎ and the negative electrode (graphite) subjected to a ceramic coating on the electrode according to FIG.
FIG. 5 is a graph showing the distribution of the cross-section and the element obtained through a focused ion beam on a cathode (LiCoO ₂ ) and a cathode (graphite) coated with a ceramic according to FIG. 2 by SEM-EDS The results are analyzed.
6 and 7 are the results of analyzes by X-ray diffraction (XRD) for the electrode subjected to ZrO ₂ ceramic coating for the positive electrode (LiCoO ₂₎ and the negative electrode (graphite) according to Figure 2.
8 and 9 are graphs showing the relationship between the ZrO ₂ ceramic coated anode and the non-ceramic coated electrode on the anode (LiCoO ₂ ) and cathode (graphite) according to the present invention at room temperature, 0.1 C And FIG. 10 and FIG. 11 are graphs showing changes in specific capacity when the charge / discharge rate varies from 0.1C to 3C.
Figure 12 and Figure 13 is a graph showing the positive electrode in the same cell condition (LiCoO ₂₎ and a negative charge at a 1C rate of about about (graphite), maintaining long-term driving under the condition that the discharge rate of 3C in capacity characteristics.

Hereinafter, embodiments and examples of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. However, the present invention may be embodied in many different forms, and is not limited to the embodiments and examples described herein.

Example

I. Coating solution preparation

(Volume ratio) of lithium secondary battery electrode coating solution in which zirconium (IV) isopropoxide or zirconium (IV) isobutoxide was diluted four times with isopropanol was prepared.

II. Manufacture of electrode and cell with coating solution

&Lt; Example 1 >

A positive electrode slurry prepared by mixing lithium cobalt oxide (LiCoO ₂ ), a conductive material (Super-P) and a binder (PVdF) in a weight ratio of 90: 5: 5 was applied to Al foil and dried at 60 ° C to prepare a positive electrode plate. The electrode plate was punched by using a punch having a diameter of 12 mm, and then immersed in the coating solution, and then the immersed electrode was taken out and naturally dried in air at room temperature. After drying, a mixed solution of EC: DEC = 1: 1 (volume ratio) in which 1 M LiPF ₆ was dissolved was injected into the electrode as a counter electrode (reference electrode) in a glove box in an Ar atmosphere to prepare a CR2032 coin half cell .

&Lt; Example 2 >

An anode slurry was prepared by mixing graphite and binders SBR and CMC in a weight ratio of 96: 2: 2 to Cu foil and drying at 60 ° C. The electrode plate was punched by using a punch having a diameter of 12 mm, and then immersed in the coating solution, and then the immersed electrode was taken out and naturally dried in air at room temperature. After drying, a mixed solution containing EC: DEC = 1: 1 (volume ratio) and 10 wt% FEC in which 1 M LiPF ₆ was dissolved was injected into the electrode as a counter electrode (Reference Electrode) in a glove box in an Ar atmosphere, A CR2032 coin half cell was prepared.

&Lt; Comparative Example 1 &

A CR2032 coin half cell was prepared in the same manner as in Example 1 except that a positive electrode plate not coated with the coating solution was used.

&Lt; Comparative Example 2 &

A CR2032 coin half cell was prepared in the same manner as in Example 2 except that the negative electrode plate to which the coating solution was not applied was used.

Physicochemical properties

The physicochemical properties of the batteries prepared according to Examples 1 and 2 and Comparative Examples 1 and 2 were evaluated.

3 is an electrode surface pictures before and after carrying out the ceramic coating on the electrode according to FIG. 2, FIG. 4, the angle of contact with the positive electrode (LiCoO ₂₎ and the negative electrode (graphite) subjected to a ceramic coating on the electrode in accordance with Figure 2 .

Referring to FIG. 4, according to the present invention, after a metal ion forming a complex with an alkoxide is coated on an electrode, natural oxidation and drying proceeds according to reaction with water vapor in the air, and the oxidized electrode is thermodynamically stable And the contact angle is reduced. Therefore, it can be seen that a chemically stable oxide layer can be coated even if surface treatment is directly performed on the electrode without performing surface treatment on the active material as in the conventional process.

FIG. 5 is a graph showing the distribution of the cross-section and the element obtained through a focused ion beam on a cathode (LiCoO ₂ ) and a cathode (graphite) coated with a ceramic according to FIG. 2 by SEM-EDS This is the result of analysis.

Referring to FIG. 5, it can be seen that the ceramic layer is mainly distributed on the surface of the electrode obtained according to the present invention. It is considered that the ceramic element is detected inside the electrode due to the diffusion of the ceramic cation.

6 and 7 are the results of analyzes by X-ray diffraction (XRD) for the electrode subjected to ZrO ₂ ceramic coating for the positive electrode (LiCoO ₂₎ and the negative electrode (graphite) according to Figure 2.

Referring to FIGS. 6 and 7, when the electrodes coated with the positive electrode (LiCoO ₂ ), the electrode coated with the negative electrode (graphite), and the electrode not coated with the ceramic, the lattice constants and the positions of the peaks are almost not different . This means that the ceramic coating layer does not affect lattice shrinkage or expansion of the electrode active material particles. The results are summarized in Table 1 below.

division Comparative Example 1 (LCO-uncoated) Example 1 (LCO-Zr coating) Comparative Example 2 (Graphite-uncoated) Example 2 (Graphite-Zr coating) a [Å] 2.817 2.817 2.462 2.462 c [Å] 14.07 14.06 6.734 6.733

Charge and discharge characteristics

8 and 9 are graphs showing the relationship between the ZrO ₂ ceramic coated anode and the non-ceramic coated electrode on the anode (LiCoO ₂ ) and cathode (graphite) according to the present invention at room temperature, 0.1 C To-charge ratio.

8 and 9 show the results of measurement of the values of 0.1 (absolute value) of the electrode (Comparative Example 1 and Comparative Example 2) in which the ZrO ₂ layer was naturally oxidized and dried according to the present invention and the ZrO ₂ layer was not formed C refer to the initial charge-discharge results if, it can be seen that the charge and discharge characteristics of the electrode layer formed of a ZrO ₂ specific capacity and charge-discharge efficiency is slightly lower than the electrode that the ZrO ₂ layer is formed. The results are summarized in Table 2 below.

division Charge [mAh / g] Discharge [mAh / g] efficiency [%] Comparative Example 1 (LCO_Bare) 153.6 150.3 97.8 Example 1 (LCO_Zr Coating) 145.4 140.9 96.9

Figs. 10 and 11 are graphs showing changes in specific capacity when the charge / discharge speed varies from 0.1C to 3C. Fig.

(Example 1 and Example 2) in which a ZrO ₂ layer was formed by natural oxidation and drying according to the present invention in FIGS. 10 and 11) and an electrode in which a ZrO ₂ layer was not formed (Comparative Example 1 and Comparative Example 2) Referring to the rate characteristic results, it can be seen that the higher the C-rate of the electrode having the ZrO ₂ layer, the better the rate characteristic than the electrode having no ZrO ₂ layer. The higher the C-rate is, the better the safety is achieved because the explosion risk is reduced and the safety is secured. The results are summarized in Tables 3 and 4 below.

anode Comparative Example 1 (LCO-uncoated) Example 1 (LCO-Zr coating) Average capacity [mAh / g] etc. 0.1C [%] Average capacity [mAh / g] etc. 0.1C [%] 0.1 C 149.8 100.0 138.9 100.0 0.2C 146.1 97.6 135.3 90.3 0.5 C 141.1 94.2 132.4 88.4 1C 120.1 80.2 124.0 82.8 3C 105.6 70.5 118.3 79.0

cathode Comparative Example 2 (Graphite-uncoated) Example 2 (Graphite-Zr coating) Average capacity [mAh / g] etc. 0.1C [%] Average capacity [mAh / g] etc. 0.1C [%] 0.1 C 315.8 100.0 307.1 100.0 0.2C 306.8 97.1 299.1 94.7 0.5 C 243.1 77.0 283.8 89.8 1C 225.8 71.5 259.6 82.2 3C 190.3 60.2 207.3 65.6

FIGS. 12 and 13 are graphs showing capacity retention characteristics during long-term operation under the condition of charging at a rate of 1C for positive electrode (LiCoO ₂ ) and negative electrode (graphite) under the same battery condition, and discharging at a rate of 3C.

12 and 13 show the results of measurement of the lifetime of the electrode (Comparative Example 1 and Comparative Example 2) in which the electrode (Example 1 and Example 2) in which the ZrO ₂ layer naturally oxidized and dried and the ZrO ₂ layer Referring to the characteristic results, it can be seen that the capacity retention according to charging and discharging of the electrode coated with the anode and the electrode coated with the cathode is improved as compared with the electrode not coated with the ceramic. The results are summarized in Tables 5 and 6 below.

anode
(1C charge / 3C discharge) Comparative Example 1 (LCO-uncoated) Example 1 (LCO-Zr coating) Capacity [mAh / g] Capacity retention rate [%] Capacity [mAh / g] Capacity retention rate [%] 1 ^st cycle 108.7 100.0 119.4 100.0 10 ^th cycle 106.6 98.1 119.0 99.6 30 ^th cycle 104.5 96.2 115.8 97.0 50 ^th cycle 102.5 94.3 113.6 95.2 100 ^th cycle 99.8 91.8 110.2 92.3

cathode
(1C discharge / 3C charge) Comparative Example 2 (Graphite-uncoated) Example 2 (Graphite-Zr coating) Capacity [mAh / g] Capacity retention rate [%] Volume
[mAh / g] Capacity retention rate [%] 1 ^st cycle 191.3 100.0 203.5 100.0 10 ^th cycle 196.6 102.8 201.7 99.1 30 ^th cycle 147.0 76.9 180.5 88.7 50 ^th cycle 141.5 74.0 166.7 82.0 100 ^th cycle 96.5 50.5 135.8 66.8

As described above, according to the present invention, since the ceramic coating layer can be formed on the surface of the electrode by immersing the electrode in the coating solution, followed by natural oxidation and drying, the manufacturing process is simple and economical. Also, according to the present invention, a battery including an electrode in which a ceramic coating layer is formed on a surface of an electrode can maintain or improve charge / discharge characteristics such as capacity retention rate and stability.

Claims (8)

Immersing the electrode in a solution in which at least one ceramic precursor selected from the group consisting of SiO ₂ , Al ₂ O ₃ , ZrO ₂ and a metal ion complex represented by the following formula 1 is dispersed; And
Drying the electrode immersed in the solution to oxidize the ceramic precursor; A lithium secondary battery electrode coating method comprising:
[Chemical Formula 1]
M- (OR) _n
In formula (1)
M is a group consisting of Al, Na, Li, Ca, Sr, Ba, Zr, Hf, La, Y, Ge, Sc, Sb, Sm, Nb, Yb, Pr, Gd, K, Sn, A transition metal selected from the group consisting of a transition metal,
R is a hydrocarbon having 2 to 6 carbon atoms,
n is an integer of 2 to 4;
The method according to claim 1,
The ceramic precursor is at least one selected from the group consisting of metal ion complexes represented by the general formula (1)
M is a group consisting of Al, Na, Li, Ca, Sr, Ba, Zr, Hf, La, Y, Ge, Sc, Sb, Sm, Nb, Yb, Pr, Gd, K, Sn, And a transition metal,
R is an alkyl group having 3 to 4 carbon atoms,
n is an integer of 2 to 4;
The method according to claim 1,
Wherein the ceramic precursor comprises a metal ion complex having a structural formula of any one of the following structural formulas:

.
The method according to claim 1,
Wherein the ceramic precursor is zirconium (IV) isopropoxide or zirconium (IV) isobutoxide.
Comprising a ceramic oxide layer on at least one side,
Wherein the ceramic oxide layer is made of a material selected from the group consisting of Si, Zr, Al, Na, Li, Ca, Sr, Ba, Zr, Hf, La, Y, Ge, Sc, Sb, Sm, Nb, Yb, Pr, Ta, In, and Mg. 2. The lithium secondary battery electrode according to claim 1, wherein the metal is selected from the group consisting of Ta, In, and Mg.
6. The method of claim 5,
Wherein the ceramic oxide layer comprises ZrO ₂ .
anode;
cathode; And
A separation membrane interposed between the anode and the cathode; And
Non-aqueous electrolyte solution containing lithium salt; / RTI &gt;
At least one of the group consisting of the positive electrode and the negative electrode includes a ceramic oxide layer on at least one side,
Wherein the ceramic oxide layer is made of a material selected from the group consisting of Si, Zr, Al, Na, Li, Ca, Sr, Ba, Zr, Hf, La, Y, Ge, Sc, Sb, Sm, Nb, Yb, Pr, Ta, In, and Mg. The lithium secondary battery according to claim 1, wherein the metal is selected from the group consisting of Ta, In, and Mg.
8. The method of claim 7,
Wherein the ceramic oxide layer comprises ZrO ₂ .

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