KR20130116027A - The method for preparing electrodes and the electrodes prepared by using the same - Google Patents

Abstract

The present invention is a method of manufacturing an electrode for secondary batteries, the electrode mixture is coated on one side or both sides of the electrode current collector, (i) the primary electrode by first coating the electrode mixture with a relatively high conductive material content on the electrode current collector Forming a coating layer; And (ii) secondary coating the electrode mixture containing no conductive material or the electrode mixture having a relatively small content of conductive material on the primary coated electrode to form a secondary coating layer. It provides a method and a secondary battery electrode prepared by the manufacturing method.

Description

Method for preparing an electrode and an electrode manufactured using the same {The Method for Preparing Electrodes and the Electrodes Prepared by Using the Same}

The present invention is a method for manufacturing an electrode for a secondary battery, the electrode mixture is coated on one side or both sides of the electrode current collector, (i) the primary coating layer by primary coating the electrode mixture with a relatively high content of the conductive material on the electrode current collector Forming a; And (ii) secondary coating the electrode mixture containing no conductive material or the electrode mixture having a relatively small content of conductive material on the primary coated electrode to form a secondary coating layer. It relates to a secondary battery electrode produced by the method and the manufacturing method.

As technology development and demand for mobile devices have increased, there has been a rapid increase in demand for secondary batteries as energy sources. Among such secondary batteries, lithium secondary batteries, which exhibit high energy density and operational potential, long cycle life, Batteries have been commercialized and widely used.

In recent years, there has been a growing interest in environmental issues, and as a result, electric vehicles (EVs) and hybrid electric vehicles (HEVs), which can replace fossil-fueled vehicles such as gasoline vehicles and diesel vehicles, And the like. Lithium secondary batteries having high energy density, high discharge voltage and output stability are mainly used as power sources for electric vehicles (EV) and hybrid electric vehicles (HEV).

The lithium secondary battery has a structure in which a non-aqueous electrolyte containing a lithium salt is impregnated in an electrode assembly having a porous separator interposed between a positive electrode and a negative electrode coated with an active material on an electrode current collector.

In such an electrode structure, the electrode mixture portion in contact with the current collector must transfer electrons to the electrode active material far from the current collector, so that the electron conductivity is high. On the other hand, the electrode mixture portion far from the current collector is required to have excellent electrolyte wettability and ionic conductivity with the electrolyte, and to be advantageous in discharging gas that may occur during charge and discharge.

Therefore, there is a very high need for an electrode having a high electron conductivity near the current collector and a method of manufacturing the same.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems of the prior art and the technical problems required from the past.

After extensive research and various experiments, the inventors of the present application first coat an electrode mixture having a relatively high content of a conductive material, and do not contain a conductive material or have a relatively low content, as described later. When using the method including secondary coating of an electrode mixture, it was confirmed that a desired effect can be achieved, and the present invention was completed.

Therefore, as a method of manufacturing the electrode for secondary batteries in which the electrode mixture is applied to one surface or both surfaces of the electrode current collector,

(i) first coating an electrode mixture having a relatively high content of conductive material on the electrode current collector to form a primary coating layer; And

(ii) second coating the electrode mixture containing no conductive material or the electrode mixture having a relatively small content of conductive material on the primary coated electrode to form a secondary coating layer;

It provides a method for manufacturing a secondary battery electrode comprising a.

The relatively high and low content of the conductive material compares the conductive material content of the electrode mixture slurry for the primary coating and the electrode mixture slurry for the secondary coating.

In one specific example, the conductive material content of the primary coating electrode mixture may be in the range of 1 to 10% by weight based on the total weight of the primary coating electrode mixture solids. If the content of the conductive material is less than 1% by weight, the desired electronic conductivity may not be exhibited. If the content of the conductive material is more than 10% by weight, the content of the active material may be relatively decreased, which may reduce the capacity.

In one specific example, the conductive material content of the secondary coating electrode mixture may be in the range of 0 to 9% by weight based on the total weight of the secondary coating electrode mixture solids in a range less than the conductive material content of the primary coating electrode mixture. have. If the content of the conductive material is more than 9%, it is not preferable because there is not much difference from the primary coating because a desired difference in electronic conductivity cannot be obtained.

In this case, the solid content means materials other than the solvent, and examples thereof include an active material, a conductive material, a binder, and the like.

In one specific example, the thickness ratio of the primary coating layer and the secondary coating layer may be 30:70 to 70:30, in detail, may be 45:55 to 55:45. Outside of the above range, if the thickness of the primary coating layer is too small, the content of the conductive material is relatively reduced, it is difficult to exert an effect of improving the electronic conductivity, and if the thickness of the secondary coating layer is too small, the content of the active material is relatively It is not desirable because it can be reduced and the dose reduced.

In the manufacturing method of the electrode, it may further comprise a drying process after the primary coating. It is possible to apply a mixture layer with a small content of the conductive material on the mixture layer with a high conductive material content without a drying process, but when the drying process, it is effective to prevent the mixture between the mixture.

The method of manufacturing the electrode may further include a process of drying and pressing the electrode after the secondary coating.

The present invention also provides a secondary battery electrode manufactured by the above manufacturing method.

In one specific example, the electrode may have a greater amount of 50% of the conductive material closer to the current collector than the 50% of the conductive material farther from the current collector based on the thickness direction. When the structure is as described above, the density of the conductive material closer to the current collector is high, the electronic conductivity is excellent, and the farther away from the current collector can replenish the active material as the conductive material is reduced, thereby optimizing the capacity and the electronic conductivity. have.

The secondary battery electrode may be a cathode including a cathode active material or an anode active material.

The positive electrode for a secondary battery is prepared by applying a mixture of a positive electrode active material, a conductive material and a binder on a positive electrode current collector, followed by drying and pressing. If necessary, a filler may be further added to the mixture.

The cathode current collector generally has a thickness of 3 to 500 mu m. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon, aluminum or stainless steel A surface treated with carbon, nickel, titanium, silver or the like may be used. The current collector may have fine irregularities on the surface thereof to increase the adhesive force of the cathode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible.

The cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _{2 -x} O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; A Ni-site type lithium nickel oxide expressed by the formula LiNi _1-x M _x O ₂ (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); Formula _{LiMn 2-x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); A lithium manganese composite oxide having a spinel structure represented by LiNi _x Mn _2-x O ₄ ; LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like. However, the present invention is not limited to these.

In one specific example, the cathode active material may be a lithium manganese composite oxide having a spinel structure, which is a high potential oxide represented by Chemical Formula 1.

Li _x M _y Mn _{2 - y} O _{4 - z z} (1)

Wherein 0 < y < 2, 0 z < 0.2,

M is at least one element selected from the group consisting of Al, Mg, Ni, Co, Fe, Cr, V, Ti, Cu, B, Ca, Zn, Zr, Nb, Mo, Sr, Sb, W, ;

A is one or more of an anion of -1 or -2.

In detail, the lithium manganese composite oxide may be a lithium nickel manganese composite oxide represented by the following Chemical Formula 2, and more specifically, LiNi _0.5 Mn _1.5 O ₄ or LiNi _0.4 Mn _1.6 O ₄ .

Li _x Ni _y Mn _2-y O ₄ (2)

In the above formula, 0.9? X? 1.2 and 0.4? Y? 0.5.

The conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The binder is a component that assists in bonding of the active material and the conductive material and bonding to the current collector, and is usually added in an amount of 1 to 50 wt% based on the total weight of the mixture containing the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.

The filler is optionally used as a component for suppressing the expansion of the anode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

On the other hand, the negative electrode is manufactured by applying, drying and pressing an anode active material on an anode current collector, and may optionally further include a conductive material, a binder, a filler, and the like as described above.

The negative electrode current collector is generally made to have a thickness of 3 to 500 mu m. Such an anode current collector is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples of the anode current collector include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, a surface of copper or stainless steel A surface treated with carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like can be used. In addition, like the positive electrode collector, fine unevenness can be formed on the surface to enhance the bonding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams and nonwoven fabrics.

The negative electrode active material may include, for example, carbon such as non-graphitized carbon or graphite carbon; _{Li x Fe 2 O 3 (0≤x≤1} ), Li x WO 2 (0≤x≤1), Sn x Me 1-x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me' : Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, Halogen, 0 &lt; x &lt; Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, and Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials; Titanium oxide; Lithium titanium oxide and the like can be used.

In one specific example, the negative electrode active material may be a lithium metal oxide represented by the following Chemical Formula 3.

Li _a M ' _b O _{4-ca c} (3)

In the above formula, M 'is at least one element selected from the group consisting of Ti, Sn, Cu, Pb, Sb, Zn, Fe, In, Al and Zr;

a and b are 0.1? a? 4; Is determined according to the oxidation number of M 'in the range of 0.2? B? 4;

c is determined according to the oxidation number in the range of 0? c <0.2;

A is one or more of an anion of -1 or -2.

Specifically, the lithium metal oxide of Formula 3 may be lithium titanium oxide (LTO) represented by the following formula (4), specifically Li _0.8 Ti _2.2 O ₄ , Li _2.67 Ti _1.33 O ₄ , LiTi ₂ O ₄ , Li _1.33 Ti _1.67 O ₄ , Li _1.14 Ti _1.71 O _4, etc., but if the lithium ions can be occluded / released there is no restriction in the composition and type, and more specifically, the crystal structure of the charge and discharge It may be Li _1.33 Ti _1.67 O ₄ or LiTi ₂ O ₄ of the spinel structure with little change and excellent reversibility.

Li _a Ti _b O ₄ (4)

In the above formula, 0.5? A? 3, 1? B? 2.5.

In one example, when lithium titanium oxide (LTO) is used as the negative electrode active material, the electrode structure as described above is preferable because the electron conductivity of LTO itself is low. In this case, it is preferable to use a spinel lithium nickel manganese composite oxide of Li _x Ni _y Mn _2-y O ₄ represented by Formula 2 having a relatively high potential due to the high potential of LTO as the positive electrode active material.

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

The separation membrane is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 mu m and the thickness is generally 5 to 300 mu m. Such separation membranes include, for example, olefinic polymers such as polypropylene, which are chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane.

The electrolyte solution containing the lithium salt is composed of an electrolyte solution and a lithium salt. The electrolyte solution may be a non-aqueous organic solvent, an organic solid electrolyte, or an inorganic solid electrolyte, but is not limited thereto.

Examples of the non-aqueous organic solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma -Butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane , Acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate Nonionic organic solvents such as tetrahydrofuran derivatives, ethers, methyl pyrophosphate, ethyl propionate and the like can 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, A polymer containing an ionic dissociation group and the like may be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides, sulfates, and the like of Li, such as Li ₄ SiO ₄ -LiI-LiOH, Li ₃ PO ₄ -Li ₂ S-SiS ₂ , and the like, may be used.

The lithium salt is a material that is readily soluble in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO 4, LiBF 4, LiB 10 Cl 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 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide.

For the purpose of improving the charge / discharge characteristics and the flame retardancy, the electrolytic solution is preferably mixed with an organic solvent such as pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, Benzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, . In some cases, halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further added to impart nonflammability. In order to improve the high-temperature storage characteristics, carbon dioxide gas may be further added. FEC (Fluoro-Ethylene Carbonate, PRS (Propene sultone), and the like.

In one specific example, lithium salts such as LiPF ₆ , LiClO ₄ , LiBF ₄ , LiN (SO ₂ CF ₃ ) _2, and the like, may be prepared by cyclic carbonate of EC or PC, which is a highly dielectric solvent, and DEC, DMC, or EMC, which are low viscosity solvents. Lithium salt-containing non-aqueous electrolyte can be prepared by adding to a mixed solvent of linear carbonate.

The present invention also provides a battery module including the secondary battery as a unit cell, and a battery pack including the battery module.

The battery pack may be used as a power source for devices requiring high temperature stability, long cycle characteristics, high rate characteristics, and the like.

Specific examples of the device include a power tool moving by being driven by an electric motor; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; And a power storage system, but the present invention is not limited thereto.

As described above, in the method for manufacturing a secondary battery electrode according to the present invention, since the amount of the conductive material in the 50% closer to the current collector is greater than the amount of the conductive material in the 50% far away from the current collector, the electron conductivity is increased. Improved, there is an effect of improving the electrochemical performance of the secondary battery comprising the same.

Hereinafter, the present invention will be described in further detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

&Lt; Example 1 >

Cathode manufacturing

Li _1.33 Ti _1.67 O ₄ is used as a negative electrode active material, and a conductive material (carbon black) and a binder (PVdF) are added to NMP (N-methyl-2-pyrrolidone) in a weight ratio of 89: 6: 5, respectively, and mixed. A negative electrode mixture was prepared, and the materials were placed in NMP at a weight ratio of 91: 4: 5 and mixed to prepare a second negative electrode mixture.

The prepared first negative electrode mixture was coated with 20 μm thick copper foil at a thickness of 40 μm and dried, and the second negative electrode mixture was coated on the first negative electrode mixture coating layer with a thickness of 40 μm, and then rolled and dried to form a negative electrode. Prepared.

At this time, the porosity of the negative electrode and the adhesion of the negative electrode mixture to the negative electrode current collector were measured. As a result, the porosity was 40% and the adhesive force was 34 gf.

Manufacture of Secondary Battery

LiNi _0.5 Mn _1.5 O ₄ is used as a positive electrode active material, and a conductive material (carbon black) and a binder (PVdF) are added to NMP in a weight ratio of 90: 6.5: 3.5, respectively, mixed to prepare a positive electrode mixture, and then 20 μm thick aluminum foil Coated, rolled and dried to prepare a positive electrode.

After preparing an electrode assembly through a separator (Celgard ^TM , thickness: 20 μm) between the cathode and the anode, the electrode assembly was housed in a pouch-type battery case, and a carbonate-based series containing 1 M LiPF ₆ was present. The composite solution of was injected into an electrolyte and then sealed to prepare a lithium secondary battery.

<Example 2>

In preparing the negative electrode, a negative electrode active material (Li _1.33 Ti _1.67 O ₄ ), a conductive material (carbon black), and a binder (PVdF) were added to NMP at a weight ratio of 85:10: 5, respectively, and mixed to prepare a first negative electrode mixture. A lithium secondary battery was manufactured in the same manner as in Example 1, except that the negative electrode active material (Li _1.33 Ti _1.67 O ₄ ) and the binder (PVdF) were each mixed in NMP at a weight ratio of 95: 5 to prepare a second negative electrode mixture. Was prepared. At this time, the porosity of the voids and the adhesion of the negative electrode mixture to the negative electrode current collector were measured. As a result, the porosity was 40% and the adhesion was 34 gf.

&Lt; Comparative Example 1 &

In preparing the negative electrode, a negative electrode active material (Li _1.33 Ti _1.67 O ₄ ), a conductive material (carbon black), and a binder (PVdF) were added to NMP at a weight ratio of 90: 5: 5, respectively, and mixed to prepare a negative electrode mixture. A lithium secondary battery was manufactured in the same manner as in Example 1, except that the copper foil having a thickness of 20 μm was coated with a thickness of 80 μm, rolled, and dried to prepare a negative electrode. At this time, the porosity of the voids and the adhesion of the negative electrode mixture to the negative electrode current collector were measured. As a result, the porosity was 40% and the adhesion was 30 gf.

<Experimental Example 1>

For the lithium secondary batteries prepared in Examples 1, 2 and Comparative Example 1, the capacity at 3C rate was measured to confirm rate characteristics, and the results are shown in Table 1 below.

3C-rate, capacity ratio (%) Example 1 92.0% Example 2 91.0% Comparative Example 1 89.0%

As shown in Table 1, in the case of the battery of Examples 1 and 2 according to the present invention it can be seen that the rate characteristic is improved compared to the battery of Comparative Example 1.

The density of the conductive material in the portion close to the electrode current collector by using a method of primary coating the electrode mixture having a relatively high conductive material content and secondary coating the electrode mixture having no conductive material or having a relatively low content. This is because the electron conductivity is improved due to high. Therefore, if the manufacturing method according to the present invention is applied to both the positive electrode and the negative electrode, there is an effect that the rate characteristic is further improved.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (22)

As a method of manufacturing an electrode for secondary batteries, the electrode mixture is coated on one or both sides of the electrode current collector,
(i) first coating an electrode mixture having a relatively high content of conductive material on the electrode current collector to form a primary coating layer; And
(ii) second coating the electrode mixture containing no conductive material or the electrode mixture having a relatively small content of conductive material on the primary coated electrode to form a secondary coating layer;
Method for producing a secondary battery electrode comprising a. The method of claim 1, wherein the conductive material content of the primary coating electrode mixture is in a range of 1 to 10 wt% based on the total weight of the primary coating electrode mixture solids. The method according to claim 1, wherein the conductive material content of the secondary coating electrode mixture is in the range of 0 to 9% by weight based on the total weight of the secondary coating electrode mixture solids in a range less than the conductive material content of the primary coating electrode mixture. A method of manufacturing an electrode for a secondary battery, characterized in that. The method of claim 1, wherein the thickness ratio of the primary coating layer and the secondary coating layer is 30:70 ~ 70:30. The method of claim 4, wherein the thickness ratio of the primary coating layer and the secondary coating layer is 45:55 ~ 55:45. The method of claim 1, wherein after the primary coating, a drying process is added. The method of claim 1, wherein the secondary coating includes a drying process and a pressing process after the secondary coating. A secondary battery electrode, which is produced by the manufacturing method according to any one of claims 1 to 7. The method of claim 8, wherein the electrode is a secondary battery electrode, characterized in that the amount of the conductive material 50% closer to the current collector closer to the current collector in the thickness direction than the amount of 50% conductive material far from the current collector. The electrode for secondary batteries of claim 8, wherein the electrode is a positive electrode or a negative electrode. The electrode of claim 10, wherein the cathode is a high voltage cathode including a lithium manganese composite oxide having a spinel structure represented by Chemical Formula 1 as a cathode active material:
Li _x M _y Mn _{2 - y} O _{4 - z z} (1)
Wherein 0 < y < 2, 0 z < 0.2,
M is at least one element selected from the group consisting of Al, Mg, Ni, Co, Fe, Cr, V, Ti, Cu, B, Ca, Zn, Zr, Nb, Mo, Sr, Sb, W, ;
A is one or more of an anion of -1 or -2. The method of claim 11, wherein the lithium manganese composite oxide of Formula 1 is a lithium nickel manganese complex oxide (Lithium Nickel Manganese complex oxide: LNMO) represented by the formula (2):
Li _x Ni _y Mn _2-y O ₄ (2)
In the above formula, 0.9? X? 1.2 and 0.4? Y? 0.5. The method of claim 12, wherein the lithium nickel manganese composite oxide of Formula 2 is LiNi _0.5 Mn _1.5 O ₄ or LiNi _0.4 Mn _1.6 O _{4 The} electrode for secondary batteries, characterized in that. The method of claim 10, wherein the negative electrode is a negative electrode active material for a secondary battery comprising a lithium metal oxide represented by the following formula (3):
Li _a M ' _b O _{4-ca c} (3)
In the above formula, M 'is at least one element selected from the group consisting of Ti, Sn, Cu, Pb, Sb, Zn, Fe, In, Al and Zr;
a and b are 0.1? a? 4; Is determined according to the oxidation number of M 'in the range of 0.2? B? 4;
c is determined according to the oxidation number in the range of 0? c <0.2;
A is one or more of an anion of -1 or -2. The method of claim 14, wherein the lithium metal oxide of Formula 3 is a lithium titanium oxide (Lithium Titanium Oxide: LTO) represented by the formula (4):
Li _a Ti _b O ₄ (4)
In the above formula, 0.5? A? 3, 1? B? 2.5. The electrode of claim 15, wherein the lithium titanium oxide is Li _1.33 Ti _1.67 O ₄ or LiTi ₂ O ₄ . A secondary battery comprising the electrode according to claim 8. The secondary battery of claim 17, wherein the secondary battery is a lithium secondary battery. A battery module comprising the secondary battery according to claim 17 as a unit cell. A battery pack comprising the battery module according to claim 19. Device comprising a battery pack according to claim 20. 22. The device of claim 21, wherein the device is an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a system for power storage.