KR101481993B1 - Electrode Comprising Compound Having Cyano group and Lithium Secondary Battery Comprising The Same - Google Patents

Abstract

The present invention provides a lithium secondary battery comprising an electrode mixture layer containing an electrode active material, a conductive material and a binder for a secondary battery for intercalating and deintercalating lithium ions, the binder being a compound containing a cyano group (-CN) And a lithium secondary battery including the electrode.

Description

TECHNICAL FIELD [0001] The present invention relates to an electrode including a compound containing a cyano group, and a lithium secondary battery comprising the same. [0002] Electrode Comprising Compound Having Cyano group and Lithium Secondary Battery Comprising The Same [

The present invention relates to a secondary battery capable of repeated charge and discharge and an electrode constituting the secondary battery.

The increase in the price of energy sources due to the depletion of fossil fuels, the increase of interest in environmental pollution, and the demand for environmentally friendly alternative energy sources are becoming indispensable factors for future life. Various researches on power generation technologies such as nuclear power, solar power, wind power, and tidal power have been continuing, and electric power storage devices for more efficient use of such generated energy have also been attracting much attention.

Particularly, in the case of a lithium secondary battery, the demand for an energy source is rapidly increasing due to an increase in technology development and demand for a mobile device. Recently, the use of a lithium secondary battery as a power source for an electric vehicle (EV) and a hybrid electric vehicle , And the area of use is also expanding for applications such as power assisted power supply through gridization.

The binder plays an important role in mechanically stabilizing the electrode.

The expansion and contraction of the electrode repeatedly proceeds according to the charge and discharge of the cell. When such deformation occurs, the bond between the active material or the conductive material is loosened and the contact resistance between the particles is increased. As a result, the ohmic resistance of the electrode rises and the battery characteristics deteriorate.

These problems are caused by the degradation of the mechanical stability of the electrode, which can be solved by the use of a binder.

However, the use of an excessive amount of the binder not only reduces the electrode active material ratio, but also causes the binder itself to act as a resistance element in the electrode, thereby reducing the performance of the battery.

On the other hand, the insufficient adhesive force causes electrode peeling phenomenon in the process of electrode drying, pressing and the like, thereby increasing the defective electrode ratio. In addition, peeling of the electrode may occur due to an external impact, which may adversely affect stability such as lifetime characteristics of the battery.

Therefore, it is necessary to design an electrode that differentiates the kind of the binder according to the characteristics of the electrode active material and can realize effective adhesion and performance.

The present invention provides an electrode comprising a compound containing a cyano group (-CN) as a binder within a predetermined content range, and a lithium secondary battery comprising the same.

According to the present invention,

An electrode mixture layer containing an electrode active material for a secondary battery for intercalating and deintercalating lithium ions, a conductive material and a binder is formed on the electrode current collector, and the binder includes a compound containing a cyano group (-CN) Thereby providing an electrode that is characterized by

The present invention also provides a lithium secondary battery having a structure in which an electrode assembly having a positive electrode, a negative electrode, and a polymer film interposed between an anode and a cathode is housed in a battery case and sealed. The lithium secondary battery may include a non-aqueous electrolyte containing a lithium salt.

The lithium secondary battery may be a lithium ion battery, a lithium ion polymer battery, or a lithium polymer battery.

The electrode may be a positive electrode or a negative electrode, and may be manufactured by a manufacturing method including the following processes.

In the electrode manufacturing method,

Dispersing or dissolving the binder in a solvent to prepare a binder solution;

Preparing an electrode slurry by mixing the binder solution, the electrode active material, and the conductive material;

Coating the electrode slurry on a current collector;

Drying the electrode; And

And compressing the electrode to a predetermined thickness.

In some cases, the rolled electrode may further be dried.

The binder solution preparation process is a process of dispersing or dissolving the binder in a solvent to prepare a binder solution.

The binder may comprise a compound comprising a cyanide group.

The compound containing a cyano group may be selected from the group consisting of cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoacrylate, cyanoethylsucrose, (Acrylonitrile-co-methacrylic acid), poly (acrylonitrile-co-methyl acrylonitrile, poly (acrylonitrile-co-methyl methacrylate) Lauryl methacrylate, lithium acrylate-lauryl methacrylate, and the like), but is not limited thereto.

The compound containing the cyano group may be an acrylonitrile compound, and specifically may be polyacrylonitrile.

The content of the compound containing a cyano group may be 2% by weight or more and 6% by weight or less based on the total weight of the electrode mixture.

When the content of the compound containing a cyano group is less than 2% by weight, the adhesive strength is less than 8 N / m, and thus the ohmic resistance of the electrode is increased to deteriorate the battery characteristics. If the content is more than 6% by weight, Group is not preferable because it acts as a resistor.

Within the above range, it may have an adhesive strength in the range of 8.0 N / m or more and less than 130 N / m.

The binder may further include all binders known in the art. Specific examples of the binder include fluororesins, polyolefins, styrene-butadiene rubber, carboxymethylcellulose, mussel proteins (dopamine), silanes, ethylcellulose , Methylcellulose, hydroxypropylcellulose, polyethylene glycol, polyvinyl alcohol, and acrylic copolymers.

The solvent can be selectively used depending on the type of the binder. For example, organic solvents such as isopropyl alcohol, N-methylpyrrolidone (NMP), and acetone and water can be used.

As a specific example of the present invention, a binder solution for a positive electrode may be prepared by dispersing / dissolving PVdF in NMP (N-methyl pyrrolidone), or a styrene-butadiene rubber (SBR) / carboxy methyl cellulose (CMC) To prepare a negative electrode binder solution.

An electrode active material and a conductive material may be mixed / dispersed in the binder solution to prepare an electrode slurry. The electrode slurry thus prepared can be transferred to a storage tank and stored until the coating process. In order to prevent the electrode slurry from hardening in the storage tank, the electrode slurry can be agitated continuously.

The electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ) or lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + y} Mn _2-y O ₄ (where y is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ and LiMnO ₂ ; 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 ; Formula _{LiNi 1-y M y O 2} ( where, the M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, y = 0.01 ~ 0.3 Im) Ni site type lithium nickel oxide which is represented by; Formula _{LiMn 2-y M y O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, y = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); 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 , non-graphitized carbon, and 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 < x < 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, Bi ₂ O ₅ and the like; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials, and the like. However, the present invention is not limited thereto.

In a non-limiting embodiment of the present invention, the electrode active material may include a lithium metal oxide, and the lithium metal oxide may preferably be represented by the following formula (1).

Li _a M ' _b O _{4-ca c} (1)

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 oxide of the above formula (1) can be represented by the following formula (2).

Li _a Ti _b O ₄ (2)

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

The lithium metal oxide may be 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, or the like. However, the present invention is not limited to these.

In a non-limiting embodiment of the present invention, the lithium metal oxide may be Li _1.33 Ti _1.67 O ₄ or LiTi ₂ O ₄ . Li _1.33 Ti _1.67 O ₄ has a spinel structure with less change in crystal structure during charging and discharging and excellent reversibility.

The lithium metal oxide can be produced by a production method known in the art and can be produced by, for example, a solid phase method, a hydrothermal method, a sol-gel method, or the like. A detailed description thereof will be omitted.

The lithium metal oxide may be in the form of secondary particles in which primary particles are aggregated.

The particle size of the secondary particles may be 200 nm to 30 탆.

If the particle diameter of the secondary particles is less than 200 nm, an extremely large surface area is not preferable because a high proportion of the binder content is required to adhere the electrode to the current collector, and a side reaction with the electrolyte may also be promoted.

Also, in a non-limiting embodiment of the present invention, the electrode active material may include a lithium metal oxide having a spinel structure represented by the following chemical formula (3).

Li _x M _y Mn _2-y O _{4 -z z} (3)

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 maximum substitution amount of A may be less than 0.2 mol%. In a specific embodiment of the present invention, A may be at least one anion selected from the group consisting of halogens such as F, Cl, Br, I, S and N.

By substituting these anions, the binding force with the transition metal is improved and the structural transition of the compound is prevented, so that the lifetime of the battery can be improved. On the other hand, if the substitution amount of the anion A is too large (t? 0.2), the life characteristic is deteriorated due to the incomplete crystal structure, which is not preferable.

Specifically, the oxide of the formula (3) may be a lithium metal oxide represented by the following formula (4).

Li _x Ni _y Mn _2-y O ₄ (4)

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

More specifically, the lithium metal oxide may be LiNi _0.5 Mn _1.5 O ₄ or LiNi _0.4 Mn _1.6 O ₄ .

The conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite such as natural graphite or 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 whiskey 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.

A filler or the like may be optionally added to the electrode slurry as required.

The filler is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery, and examples thereof include olefin-based polymerizers such as polyethylene and polypropylene; Fibrous materials such as glass fiber, carbon fiber and the like can be used.

The process of coating the electrode slurry on the current collector is a process in which the electrode slurry is passed through a coater head to coat the current collector with a predetermined pattern and a constant thickness.

The method of coating the electrode slurry on the current collector includes a method of uniformly dispersing the electrode slurry on a current collector using a doctor blade or the like, a method of die casting, comma coating coating, screen printing, and the like. Alternatively, the electrode slurry may be bonded to the current collector by molding on a separate substrate, followed by pressing or lamination.

The current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery. For example, the current collector may be made of 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. The positive electrode current collector may be formed into various shapes such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven fabric, or the like by forming fine irregularities on the surface to enhance the bonding force of the positive electrode active material. Specifically, the cathode current collector may be a metal current collector including aluminum, and the anode current collector may be a metal current collector including copper. The electrode current collector may be a metal foil, and may be an aluminum foil or a copper foil.

The drying process is a process of removing the solvent and moisture in the slurry to dry the slurry coated on the metal current collector. In a specific example, the drying process is performed within one day in a vacuum oven at 50 to 200 ° C.

After the drying process, a cooling process may be further included, and the cooling process may be a slow cooling process to room temperature to form a recrystallized structure of the binder.

In order to increase the capacity density of the coated electrode and increase the adhesion between the current collector and the active materials, an electrode can be passed between two rolls heated at a high temperature and compressed to a desired thickness. This process is called the rolling process.

The electrode can be preheated before passing the electrode between two heated, heated rolls. The preheating process is a process of preheating the electrode before it is introduced into the roll to increase the compression effect of the electrode.

The electrode having completed the rolling process as described above can be dried within one day in a vacuum oven at 50 to 200 DEG C in a range satisfying a temperature equal to or higher than the melting point of the binder. The rolled electrode may be cut to a certain length and then dried.

After the drying process, a cooling process may be further included, and the cooling process may be a slow cooling process to room temperature to form a recrystallized structure of the binder.

The polymer membrane is a separator separating the anode and the cathode. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.

The separator is made of an insulating thin film having high ion permeability and mechanical strength. 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; Kraft paper and the like are used. Representative examples currently on the market include the Celgard ^R 2400, 2300 (from Hoechest Celanese Corp.), polypropylene separator (from Ube Industries Ltd. or Pall RAI), and polyethylene series (from Tonen or Entek).

In some cases, a gel polymer electrolyte may be coated on the separation membrane to increase the stability of the cell. Representative examples of such a gel polymer include polyethylene oxide, polyvinylidene fluoride, and polyacrylonitrile.

The electrode assembly may include both a jelly-roll type electrode assembly (or a wound electrode assembly), a stacked electrode assembly (or a stacked electrode assembly), or a stacked & folded electrode assembly having a structure known in the art.

In this specification, the stacked & folded type electrode assembly is a method of arranging unit cells having a structure in which a separator is interposed between an anode and a cathode on a separator sheet, folding and winding the separator sheet A stack &amp; folding type electrode assembly.

In addition, the electrode assembly may include an electrode assembly having a structure in which one of an anode and a cathode is laminated with a structure interposed therebetween, and is laminated by a method such as thermal fusion.

As the non-aqueous electrolyte, a non-aqueous electrolyte, an organic solid electrolyte, an inorganic solid electrolyte, or the like is used.

Examples of the nonaqueous electrolyte include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate , Gamma -butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, Diethyl ether, formamide, dimethyl formamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane A non-protonic organic solvent such as an ether, a methyl pyrophosphate, or an ethyl propionate is used as the solvent, a sulfone, a methyl sulfolane, a 1,3-dimethyl-2-imidazolidinone, a propylene carbonate derivative, a tetrahydrofuran derivative, .

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.

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 and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can 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 3 Li, LiSCN, LiC (CF 3 SO 2) 3, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, 4-phenylborate, imide, and the like can be used.

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), FPC (fluoro-propylene carbonate), and the like.

The lithium secondary battery according to the present invention can exhibit a discharge capacity retention ratio of 90% or more at 3 C discharge.

The lithium secondary battery according to the present invention can be used not only in a battery cell used as a power source of a small device but also as a unit cell in a middle- or large-sized battery module including a plurality of battery cells.

Also, the present invention provides a battery pack including the battery module as a power source of a middle- or large-sized device, wherein the middle- or large-sized device is an electric vehicle (EV), a hybrid electric vehicle (HEV) An electric vehicle including a plug-in hybrid electric vehicle (PHEV), a power storage device, and the like, but the present invention is not limited thereto.

The structure of the battery module and the battery pack and the method of manufacturing the battery module and the battery pack are well known in the art, so a detailed description thereof will be omitted herein.

Since the electrode according to the present invention contains a compound containing a cyano group as a binder, it has an advantage that an excellent adhesive force can be exhibited even with a small content.

In addition, since it is contained in an amount of not less than 2% by weight and not more than 6% by weight based on the total weight of the electrode material mixture, an adhesive strength of 8 N / m or more can be exhibited even with a small amount not to act as a resistance element.

Accordingly, the binder containing a compound containing a cyano group according to the present invention is preferable in the case of using the oxides of the formulas (1) to (4), which have no volume expansion due to repetitive charging and discharging and are not excellent in electrical conductivity .

1 is a graph comparing output characteristics of non-limiting embodiments of the present invention.

Hereinafter, the present invention will be described in detail with reference to the following examples. However, the following examples are intended to illustrate the present invention, and the scope of the present invention is not limited thereto.

&Lt; Example 1 >

A solid content of Li (Ni _0.5 Mn _1.5 ) O ₄ (BASF): Super P (Timcal): PVdF (Solef 6020) in a mass ratio of 90: 5: 5 was added to an NMP solvent to prepare a positive electrode slurry Was applied to an aluminum foil having a thickness of 20 mu m to prepare a positive electrode having a loading amount of 1 mAh / cm &lt; ^{2 &} gt ;.

Li ₄ Ti ₅ O ₁₂ (Posco ESM T30): A solid component having a weight ratio of 90: 6: 4 of Super-P (Timcal): polyacrylonitrile (PAN) was added to an NMP solvent to prepare an anode slurry And applied to an aluminum foil having a thickness of 20 탆 to prepare a negative electrode having a loading amount of 1 mAh / cm ² .

A battery cell was fabricated using an electrolytic solution in which a polyethylene film (Celgard, thickness 20 탆) and a 1M LiPF ₆ salt were added to a solvent of EC: DMC: EMC = 1: 1: 1 as a separation membrane.

&Lt; Example 2 >

A battery cell was fabricated in the same manner as in Example 1 except that the mass ratio of Li ₄ Ti ₅ O ₁₂ : Super-P: polyacrylonitrile (PAN) was 90: 7: 3.

&Lt; Comparative Example 1 &

A battery cell was fabricated in the same manner as in Example 1 except that the mass ratio of Li ₄ Ti ₅ O ₁₂ : Super-P: polyacrylonitrile (PAN) was 90: 3: 7.

&Lt; Comparative Example 2 &

A solid content having a mass ratio of Li ₄ Ti ₅ O ₁₂ : Super-P: PVdF (Solef 6020) of 87: 5: 8 was put into an NMP solvent and mixed to prepare an anode slurry. The anode slurry was applied to an aluminum foil 1 mAh / cm &lt; ^{2 &} gt ;.

<Experimental Example 1>

An adhesive strength test was performed using the electrodes of Examples 1 and 2 and Comparative Examples 1 and 2. The surfaces of the electrodes of Examples 1 and 2 and Comparative Examples 1 and 2 were cut and fixed on a slide glass, and the peel strength of 180 degrees was measured while peeling off the collector. The evaluation was made by measuring the peel strengths of 5 or more and calculating the average value.

Adhesion (N / m) Example 1 21.4 Example 2 8.4 Comparative Example 1 130.2 Comparative Example 2 11.4

Referring to Table 1, Example 1 exhibited an adhesive strength of 21.4 N / m although it contained 4% by weight of polyacrylonitrile, whereas Example 2 contained 3% by weight of polyacrylonitrile, N / m, whereas Comparative Example 2 exhibits an adhesive force of 11.4 N / m even though it contains 8% by weight of PVdF. It can be confirmed from the examination of Comparative Examples 1 and 2 that Comparative Example 1 exhibits a remarkably large adhesive force as compared with Comparative Example 2, despite the difference of 1% by weight.

<Experimental Example 2>

The battery cells of Examples 1 and 2 and Comparative Example 1 were charged at 0.1 C in a voltage range of 3.4 to 4.85 V and discharged at 0.1 C, 1.0 C, and 3.0 C, respectively, and the output characteristics were measured. The results are shown in Fig. Referring to FIG. 1, it can be seen that the discharge capacity retention rate of Comparative Example 1 is gradually decreased at a high rate as compared with Embodiments 1 and 2.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (17)

A lithium secondary battery comprising an electrode assembly and a polymer membrane, wherein the electrode assembly has a structure in which a polymer membrane is interposed between an anode and a cathode,
The electrode has a structure in which an electrode mixture layer containing an electrode active material for a secondary battery that occludes and desorbs lithium ions, a conductive material, and a binder is formed on the electrode current collector,
The binder comprises a compound comprising a cyanide (-CN)
Wherein the electrode active material comprises a lithium metal oxide having a spinel structure represented by the following formula (2) or a lithium metal oxide represented by the following formula (4)
The content of the compound containing a cyano group is 2% by weight or more and 6% by weight or less based on the total weight of the electrode mixture,
The adhesive force of the electrode is in the range of 8.0 N / m or more and less than 130 N / m,
Wherein the lithium secondary battery has a discharge capacity retention ratio of 90% or more at the time of 3 C discharge.
Li _x Ni _y Mn _2-y O ₄ (2)
Wherein 0.9? X? 1.2, 0.4? Y? 0.5,
Li _a Ti _b O ₄ (4)
In the above formula, 0.5? A? 3, 1? B? 2.5. The method according to claim 1,
The compound containing a cyano group may be selected from the group consisting of cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoacrylate, cyanoethylsucrose, polyacrylonitrile, (Acrylonitrile-co-methacrylic acid), poly (acrylonitrile-co-methyl acrylonitrile, poly (acrylonitrile-co-methyl methacrylate) Lithium perchlorate, lithium perchlorate, and lithium perchlorate). The lithium secondary battery according to claim 2, wherein the compound containing a cyano group is an acrylonitrile compound. The lithium secondary battery according to claim 3, wherein the acrylonitrile compound is polyacrylonitrile. delete delete delete The lithium secondary battery according to claim 1, wherein the lithium metal oxide having a spinel structure represented by the formula (2) is LiNi _0.5 Mn _1.5 O ₄ or LiNi _0.4 Mn _1.6 O ₄ . delete delete The lithium secondary battery according to claim 1, wherein the lithium metal oxide represented by the chemical formula (4) is Li _1.33 Ti _1.67 O ₄ or LiTi ₂ O ₄ . delete The lithium secondary battery according to claim 1, wherein the lithium secondary battery is a lithium ion battery. The lithium secondary battery according to claim 1, wherein the lithium secondary battery is a lithium ion polymer battery. The lithium secondary battery according to claim 1, wherein the lithium secondary battery is a lithium polymer battery. delete delete

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