KR100834054B1 - Olivine type positive active material for lithium battery, method for preparing the same, and lithium battery comprising the same - Google Patents

Abstract

An olivine type cathode active material for a lithium battery is provided to realize excellent crystallinity and uniform size and shape of active material particles and to ensure high energy density. An olivine type cathode active material for a lithium battery comprises: a core material; and a carbon coating layer surrounding the core material, wherein the core material is represented by the formula of LixMyM'zXO4-wBw, has a particle diameter of 0.1-10 micrometers and a tap density of 0.5-2.0 g/cm^3, and the carbon coating layer has a thickness of 10-100 nm. In the formula, each of M and M' is an element selected from the group consisting of Fe, Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B and a combination thereof; X is an element selected from the group consisting of P, As, Bi, Sb, Mo and a combination thereof; B is an element selected from F, S and a combination thereof; 0<x<=1; 0<y<=1; 0<z<=1 with the proviso that 0<x+y+z<=2; and 0<=w<=0.5.

Description

OLIVINE TYPE POSITIVE ACTIVE MATERIAL FOR LITHIUM BATTERY, METHOD FOR PREPARING THE SAME, AND LITHIUM BATTERY COMPRISING THE SAME}

1 is a perspective view of a lithium battery according to an embodiment of the present invention.

2 is a scanning electron microscope (SEM) photograph of the iron-phosphate prepared in Example 1 of the present invention.

Figure 3 is a scanning electron micrograph of the olivine-type positive electrode active material prepared in Example 1 of the present invention.

4 is a scanning electron micrograph of the iron-phosphate prepared in Example 2 of the present invention.

5 is a scanning electron micrograph of the olivine-type positive electrode active material prepared in Example 2 of the present invention.

6 is a graph showing the results of X-ray diffraction analysis (XRD) of the iron-phosphate prepared in Example 1 of the present invention.

7 is a graph showing the results of X-ray diffraction analysis of the iron-phosphate prepared in Example 2 of the present invention.

8 is a graph showing the results of X-ray diffraction analysis of the olivine-type positive electrode active material prepared in Example 1 of the present invention.

9 is a graph showing the results of X-ray diffraction analysis of the olivine-type positive electrode active material prepared in Example 2 of the present invention.

10 is a graph showing the results of X-ray diffraction analysis of the olivine-type positive electrode active material prepared in Example 6 of the present invention.

11 is a graph showing the results of X-ray diffraction analysis of the olivine-type positive electrode active material prepared in Example 7 of the present invention.

12 is a graph showing the results of X-ray diffraction analysis of the olivine-type positive electrode active material prepared in Example 8 of the present invention.

13 is a graph showing the results of X-ray diffraction analysis of the olivine-type positive electrode active material prepared in Example 9 of the present invention.

14 is a graph showing a change in capacity according to a voltage change of a battery manufactured using the cathode active material prepared in Example 1 of the present invention.

15 is a graph showing discharge characteristics of a battery manufactured using the positive electrode active material prepared in Example 1 of the present invention.

<Description of reference numerals for the main parts of the drawings>

3: cathode 5: anode

9 electrode assembly 7 separator

15: case

[Industrial use]

The present invention relates to an olivine-type positive electrode active material for a lithium battery, a method for manufacturing the same, and a lithium battery including the same, more specifically, an olivine-type positive electrode active material having excellent crystallinity and high energy density, and a method for producing the same, and It relates to a lithium battery comprising the same.

[Prior art]

Recently, portable electronic devices such as mobile phones, personal digital assistants (PDAs), notebook computers, portable electronic devices such as digital cameras, camcorders, electric bicycles, electric vehicles, etc. The demand for lithium batteries is growing exponentially.

Commercially available lithium batteries use LiCoO ₂ for the positive electrode and carbon for the negative electrode. However, cobalt, which is a starting material of the positive electrode active material, has a low reserve and is expensive, and there is a demand for development of an alternative positive electrode material due to toxicity and environmental pollution problems.

LiNiO ₂ , LiCo _x Ni _{1 - x} O ₂ and LiMn ₂ O ₄ as positive electrode active materials that are currently actively researched and developed Etc. can be mentioned. LiNiO ₂ which has the same layered structure as LiCoO ₂ is not commercialized due to the difficulty in synthesizing the material in a stoichiometric ratio and the problem of thermal stability.

LiMn ₂ O ₄ , a 4V spinel cathode active material, has the advantage of using manganese as a starting material, and some of them are commercialized in low-cost products, but due to the structural variation called Jahn-Teller distortion caused by manganese ³⁺ There is a problem that the life characteristics are not good.

Therefore, there is a demand for a positive electrode active material that is more economical, stable, high capacity, and has good cycle characteristics. It has a olivine structure as a positive electrode active material of the current lithium battery and has the formula Li _x M _y PO ₄ (where x is 0 <x≤2, y is 0.8≤y≤1.2, M is a periodic table Group 3d transition metal). Research on the compound represented by is in progress.

In addition, the use of LiFePO ₄ as a positive electrode of a lithium ion battery among the compounds represented by Li _x M _y PO ₄ is disclosed in Japanese Patent Laid-Open No. 9-171827. LiFePO ₄ is environmentally friendly, rich in reserves and very low in raw material prices. In addition, it is possible to implement low power and low voltage more easily than the conventional cathode active material, the theoretical capacity is 170 mAh / g, the battery capacity is also excellent.

However, the solid phase reaction method and the sol-gel reaction method of the synthesis method of Li _x M _y PO ₄ are impossible to control the particle size and the shape of the particles, and it is difficult to synthesize a single particle powder. In addition, since the size of the formed particles is nano-size, since the volumetric energy density is low, there is a problem in the application of the actual lithium secondary battery. That is, there is a need for a new synthesis method of an olivine-type positive electrode active material that suppresses a small specific surface area and has a high volumetric energy density.

In order to solve the above problems, the present invention provides an olivine-type positive electrode active material having excellent crystallinity and high energy density.

Another object of the present invention is to provide a method for producing the olivine-type positive electrode active material for a lithium battery.

Still another object of the present invention is to provide a lithium battery including the cathode active material.

In order to achieve the above object, according to an embodiment of the present invention, a core material; And a carbon coating layer surrounding the core material, wherein the core material is represented by the following Chemical Formula 1, and has a particle diameter of 0.1 μm to 10 μm and a tap density of 0.5 to 2.0 g / cm ³ . To provide.

[Formula 1]

Li _x M _y M ' _{z X} O _{4 - w} B _w

Wherein M and M 'are independently of each other consisting of Fe, Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof Is an element selected from the group, X is an element selected from the group consisting of P, As, Bi, Sb, Mo, and combinations thereof, B is an element selected from the group consisting of F, S, and combinations thereof 0 <x≤1, 0 <y≤1, 0 <z≤1, 0 <x + y + z≤2, and 0≤w≤0.5.)

The core material preferably has a particle diameter of 0.2 μm to 8 μm and a tap density of 0.7 g / cm ³ to 1.6 g / cm ³ .

The core material is preferably selected from the group consisting of the following Chemical Formulas 2, 3, and combinations thereof.

[Formula 2]

LiFe _{1 - a} A _a PO ₄

Wherein A is an element selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof, 0 ≤ a ≤ 1)

[Formula 3]

Li _{1 - a} A _a FePO ₄

Wherein A is an element selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof, 0 ≤ a <1)

The core material is preferably selected from the group consisting of Formula 4, Formula 5, and combinations thereof.

[Formula 4]

LiFe _{1 - a} A _a PO _{4 - z} B _z

Wherein A is an element selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof, and B Is an element selected from the group consisting of F, S, and a combination thereof, 0 ≦ a ≦ 1, and 0.01 ≦ z ≦ 0.5.)

[Formula 5]

Li _{1 - a} A _a FePO _{4 - z} B _z

Wherein A is an element selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof, and B Is an element selected from the group consisting of F, S, and a combination thereof, wherein 0 ≦ a <1, 0.01 ≦ z ≦ 0.5.)

The carbon coating layer preferably has a thickness of 10 nm to 100 nm.

According to one embodiment of the invention, M-containing solution in the reactor (wherein M is Fe, Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof.), X-containing solution (where X is an element selected from the group consisting of P, As, Bi, Sb, Mo and combinations thereof), And supplying a pH adjusting agent and mixing to prepare an MX-containing hydrate; Vacuum drying the M-X-containing hydrate followed by primary firing to prepare an M-X precursor; And mixing the M-X precursor and the lithium-containing compound, followed by secondary firing to prepare a cathode active material.

The M-containing solution is preferably supplied to the reactor at a rate of 0.03 to 1.2 mol / h, the X-containing solution is preferably supplied to the reactor at a rate of 0.03 to 1.2 mol / h, the supply of the pH regulator Preferably, the pH inside the reactor is maintained at 1.5 to 9.

The mixing is preferably carried out by stirring at 500 to 1500rpm.

The M-containing solution is preferably prepared by dissolving the M-containing compound in a solvent selected from the group consisting of water, methanol, ethanol, isopropyl alcohol, and combinations thereof. And dissolved in a solvent selected from the group consisting of methanol, ethanol, isopropyl alcohol, and combinations thereof.

The pH adjusting agent is preferably selected from the group consisting of ammonia aqueous solution, carbon dioxide gas, a compound containing an OH group, and combinations thereof.

The step of preparing the M-X-containing hydrate is preferably carried out at a temperature of 30 to 70 ℃, preferably 12 to 24 hours.

The primary firing is preferably carried out at a temperature of 450 to 600 ℃, preferably for 5 to 20 hours.

The lithium-containing compound is preferably selected from the group consisting of lithium hydroxide, lithium fluoride, lithium nitrate, lithium carbonate, lithium acetate, hydrates thereof, and combinations thereof.

The secondary firing is preferably carried out at a temperature of 650 to 800 ℃, preferably for 10 to 24 hours.

According to another embodiment of the present invention, after mixing the M-X precursor and the lithium-containing compound, further comprising the step of adding a carbon precursor.

The carbon precursor is pitch, carbon nanofibers, sucrose, glucose, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), colloidal carbon, citric acid , Tartaric acid, glycolic acid, polyacrylic acid, adipic acid, glycine, and combinations thereof.

According to an embodiment of the present invention, a lithium battery including the cathode active material is provided.

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

According to one embodiment of the invention, the core material; And a carbon coating layer surrounding the core material, wherein the core material is represented by the following Chemical Formula 1, and has a particle diameter of 0.1 μm to 10 μm and a tap density of 0.5 to 2.0 g / cm ³ . To provide.

[Formula 1]

Li _x M _y M ' _{z X} O _{4 - w} B _w

Wherein M and M 'are independently of each other consisting of Fe, Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof Is an element selected from the group, X is an element selected from the group consisting of P, As, Bi, Sb, Mo, and combinations thereof, B is an element selected from the group consisting of F, S, and combinations thereof 0 <x≤1, 0 <y≤1, 0 <z≤1, 0 <x + y + z≤2, and 0≤w≤0.5.)

When the positive electrode active material further includes a carbon coating layer surrounding the core material, the electrical conductivity of the core material may be further improved, which is preferable.

The core material has a particle diameter of 0.1 to 10 mu m, preferably 0.2 to 8 mu m, and more preferably 0.5 to 5 mu m. When the particle diameter of the core material is less than 0.1 mu m, there is a problem in manufacturing the electrode due to low tap density. When the particle diameter exceeds 10 mu m, the tap density increases, but the specific surface area is too small, and the contact area with the electrolyte is also reduced. It is undesirable because it interferes with intercalation and deintercalation of ions.

It said core material has a tap density of 0.5g / cm ³ to 2.0g / cm ³ and, 0.7g / cm ³ to 1.6g / cm ³ is preferable, and a still more 0.8g / cm ³ to 1.3g / cm ³ desirable. When the tap density of the olivine-type positive electrode active material is less than 0.8 g / cm ³ , there is a problem in manufacturing the electrode because the tap density is lowered. When the tap density of the olivine-type positive electrode active material is larger than 2.0 g / cm ³ , the particle size of the positive electrode active material is increased to 10 μm or more. It is not preferable because there is a problem that the dose of is reduced.

Preferably, the core material is spherical. Here, the spherical shape may be circular or elliptical, but is not limited thereto. The core material has a spherical shape because the core material is manufactured using a spherical olivine positive electrode active material precursor.

The core material is preferably selected from the group consisting of the following Chemical Formulas 2, 3, and combinations thereof.

[Formula 2]

LiFe _{1 - a} A _a PO ₄

Wherein A is an element selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof, 0 ≤ a ≤ 1)

[Formula 3]

Li _{1 - a} A _a FePO ₄

Wherein A is an element selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof, 0 ≤ a <1)

The core material is preferably selected from the group consisting of Formula 4, Formula 5, and combinations thereof.

[Formula 4]

LiFe _{1 - a} A _a PO _{4 - z} B _z

Wherein A is an element selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof, and B Is an element selected from the group consisting of F, S, and a combination thereof, 0 ≦ a ≦ 1, and 0.01 ≦ z ≦ 0.5.)

[Formula 5]

Li _{1 - a} A _a FePO _{4 - z} B _z

Wherein A is an element selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof, and B Is an element selected from the group consisting of F, S, and a combination thereof, wherein 0 ≦ a <1, 0.01 ≦ z ≦ 0.5.)

The carbon coating layer may be prepared by further adding a carbon precursor and heat treating the core material.

It is preferable that it is 10-100 nm, and, as for the thickness of the said carbon coating layer, it is more preferable that it is 20 nm-80 nm. When the thickness of the carbon coating layer is less than 10nm, the effect of improving electric conductivity is insignificant, and when the thickness of the carbon coating layer is greater than 100nm, the intercalation and deintercalation performance of lithium is deteriorated due to the too thick carbon coating layer, thereby reducing the capacity of the battery. It is reduced, there is a problem that the tap density of the positive electrode active material is lowered.

According to one embodiment of the invention, M-containing solution in the reactor (wherein M is Fe, Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof.), X-containing solution (where X is an element selected from the group consisting of P, As, Bi, Sb, Mo and combinations thereof), And supplying a pH adjusting agent and mixing to prepare an MX-containing hydrate; Vacuum drying the M-X-containing hydrate followed by primary firing to prepare an M-X precursor; And mixing the M-X precursor and the lithium-containing compound, followed by secondary firing to prepare a cathode active material.

The MX precursor is MXO _{4 - z} B _z Wherein M is an element selected from the group consisting of Fe, Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof , X is an element selected from the group consisting of P, As, Bi, Sb, Mo, and combinations thereof, B is an element selected from the group consisting of F, S, and combinations thereof, 0≤z≤0.5 It is preferred to include particles. MXO _{4 - z} B _z More preferably is iron-phosphate.

The M-X precursor is a precursor capable of producing an olivine-type positive electrode active material for a lithium battery by mixing with a lithium-containing compound and firing. It is preferable that the said M-X precursor is spherical. Here, the spherical shape may be selected from the group consisting of a circle, an ellipse, and a combination thereof, but is not limited thereto. When manufacturing the positive electrode active material for lithium batteries using the said spherical M-X precursor, since a spherical olivine-type positive electrode active material can be manufactured, it is preferable.

The MX precursor MXO _{4 nanosized-z} B _z may be the primary particles, nano-sized MXO _4-that the primary particles of _z B _z is united consisting of secondary particles is more preferable.

The M-X precursor may be prepared by firing an M-X-containing hydrate. The M-X-containing hydrate may be prepared by feeding and mixing an M-containing solution, an X-containing solution, and a pH adjuster to the reactor.

The supply of the M-containing solution can be variously adjusted according to the composition of the M-X precursor to be prepared, it is preferable that the feed to the reactor at a rate of 0.03 to 1.2 mol / h. When the M-containing solution is supplied to the reactor at less than 0.03 mol / h, the yield of the MX-containing hydrate is not preferable, and when the M-containing solution is supplied to the reactor at more than 0.03 mol / h, the M element is well contained in the M-containing solution. It is not preferable because it does not dissolve.

In addition, the supply of the X-containing solution can be variously controlled according to the composition of the M-X precursor to be prepared, it is preferable that the feed to the reactor at a rate of 0.03 to 1.2 mol / h. When the X-containing solution is fed to the reactor at less than 0.03 mol / h, the yield of the MX-containing hydrate is not preferable, and when the X-containing solution is fed to the reactor at more than 0.03 mol / h, the X-containing solution is well It is not preferable because it does not dissolve.

The supply of the pH regulator is preferably carried out so that the pH inside the reactor is maintained at 1.5 to 9.0. When the pH regulator is supplied such that the pH inside the reactor is maintained at 1.5 to 9.0, it is preferable because uniform and hard M-X-containing hydrate particles can be obtained. In order to maintain the pH in the reactor to 1.5 to 9.0, but not limited to this, it is preferable that the concentration of the pH regulator is 2 to 5M.

The mixing is preferably performed at 500 to 1500 rpm, more preferably at 800 to 1200 rpm. If the mixing is carried out at less than 500rpm, there is a problem that a long time is required to form spherical particles because the stirring speed is too slow, and when carried out above 1500rpm, the M-containing solution and the X-containing solution do not mix well and do not react There is a problem that is discharged to the outside of the reactor.

The M-containing solution may be prepared by dissolving the M-containing compound in a solvent selected from the group consisting of water, methanol, ethanol, isopropyl alcohol, and combinations thereof.

The M-containing compound is acetate containing acetate, nitrate, sulfate, carbonate, citrate, phthalate, perchlorate, acetylacetonate (acetylacetonate), acrylate, formate, oxalate, halide, oxyhalide, boride, oxide, sulfide, Peroxide, alkoxide, hydroxide, ammonium, acetylacetone, hydrates thereof, and combinations thereof may be preferably used.

In addition, the M-containing compound is iron ethylenediammonium sulfate (Iron ethylenediammonium sulfate), titanium bis (ammonium lactato) dihydroxide (manganese monoperoxyphthalate), aluminum Aluminum phnoxide, boric acid, boron trifluoride diethyl etherate, boron trifluoride-propanol, hydrates thereof, and combinations thereof One selected from the group consisting of can be preferably used.

The X-containing solution may be prepared by dissolving the X-containing compound in a solvent selected from the group consisting of water, methanol, ethanol, isopropyl alcohol, and combinations thereof.

The X-containing compound is acetate containing acetate, nitrate, sulfate, citrate, perchlorate, halide, oxyhalide, oxide ), Sulfides, alkoxides, hydrates thereof, and combinations thereof may be preferably used.

In addition, the X-containing compound may be preferably selected from the group consisting of phosphoric acid, bismuth neodecanoate, hydrates thereof, and combinations thereof.

The pH adjusting agent is preferably selected from the group consisting of aqueous ammonia solution, carbon dioxide gas, a compound containing an OH group, and combinations thereof, and more preferably, the compound containing OH is NaOH.

The step of preparing the M-X-containing hydrate is preferably carried out at a temperature of 30 to 70 ℃. When the step of preparing the MX-containing hydrate is carried out at a temperature of less than 30 ℃, there is a problem that it takes a long time to manufacture the MX-containing hydrate is low reactivity between the M-containing solution and X-containing solution when manufacturing the MX-containing hydrate, 70 When it is carried out at a temperature exceeding ℃, the reaction between the M-containing solution and X-containing solution in the preparation of the MX-containing hydrate can reduce the reaction time, but there is a problem that unwanted by-products are produced.

The step of preparing the M-X-containing hydrate is preferably performed for 12 to 24 hours. If the step of preparing the MX-containing hydrate is less than 12 hours, there is a problem that the formed MX-containing hydrate particles are non-uniform, and if it is more than 24 hours, other sizes and shapes other than the spherical MX-containing hydrate particles to be prepared It is not desirable that new particles are formed having.

Preparing the M-X-containing hydrate may further include supplying a B-containing solution, wherein B is an element selected from the group consisting of F, S, and combinations thereof.

The B-containing solution may be prepared by dissolving the B-containing compound in a solvent selected from the group consisting of water, methanol, ethanol, isopropyl alcohol, and combinations thereof.

The B-containing compound is nickel fluoride, iron fluoride, cobalt fluoride, manganese fluoride, chromium fluoride, chromium fluoride, zirconium fluoride fluoride, niobium fluoride, copper fluoride, vanadium fluoride, titanium fluoride, zinc fluoride, aluminum fluoride , Gallium fluoride, manganese fluoride, boron fluoride, Boron fluoride, NH ₄ F, LiF, AlF ₃ , S, Li ₂ S, hydrates thereof, and combinations thereof It is preferably selected from the group.

The prepared M-X-containing hydrate was washed with distilled water, and vacuum dried at 50 to 90 ° C. for 12 to 24 hours to completely remove impurities.

If the vacuum drying temperature is less than 50 ℃ there is a problem that a long time is required to completely remove the water that is chemically adsorbed in the MX-containing hydrate particles, if it exceeds 90 ℃ if the vacuum does not remain stable MX-containing hydrate There is a problem of this oxidation. In addition, when the vacuum drying time is less than 12 hours, there is a problem in that the water that is chemically adsorbed in the MX-containing hydrate particles cannot be completely removed, and if it exceeds 24 hours, the process time is wasted because it is already completely dried. Not desirable

The vacuum dried M-X-containing hydrate was first baked to prepare an M-X precursor.

The first firing is preferably performed for 450 to 600 ℃. If the primary firing temperature is less than 450 ℃, there is a problem that the crystal of the M-X precursor is difficult to form, and if it exceeds 600 ℃, it is not preferable because the process cost and processing time is wasted.

In addition, the first firing is preferably performed for 5 to 20 hours. When the primary firing time is less than 5 hours, there is a problem in that the crystallinity of the prepared M-X precursor is not good, and when it exceeds 20 hours, the process cost and process time is wasted, which is not preferable.

The first firing step is preferably performed in an atmosphere selected from the group consisting of a reducing atmosphere, an inert atmosphere, and a combination thereof. More preferably, the atmosphere is an atmosphere selected from the group consisting of nitrogen gas, argon gas, argon / hydrogen mixed gas, and combinations thereof. In particular, when the first firing step is carried out in a reducing atmosphere, it is preferable to form an M-X precursor having a desired crystallinity from the M-X-containing hydrate.

The M-X precursor and the lithium-containing compound are mixed and then calcined to prepare a cathode active material.

The lithium-containing compound is preferably selected from the group consisting of lithium hydroxide, lithium fluoride, lithium nitrate, lithium carbonate, lithium acetate, hydrates thereof, and combinations thereof.

The secondary firing is preferably performed for 650 to 850 ℃. If the secondary firing temperature is less than 650 ° C, the capacity of the prepared positive electrode active material is reduced and not preferable, and if it exceeds 850 ° C, the capacity is also reduced, which is undesirable.

In addition, the secondary firing is preferably performed for 10 to 20 hours. If the secondary firing time is less than 10 hours, there is a problem that M is not reduced in the M-X precursor, and if more than 20 hours, there is a problem of waste processing time and process costs.

The secondary firing is preferably performed in an atmosphere selected from the group consisting of a reducing atmosphere, an inert atmosphere, and a combination thereof. More preferably, the atmosphere is an atmosphere selected from the group consisting of nitrogen gas, argon gas, argon / hydrogen mixed gas, and combinations thereof. In particular, when the secondary firing is carried out in a reducing atmosphere, M is preferably reduced in the M-X precursor to form an olivine structure.

According to another embodiment of the present invention, after mixing the M-X precursor and the lithium-containing compound, further comprising the step of adding a carbon precursor. After further adding the carbon precursor, secondary firing may form a carbon coating layer surrounding the surface of the positive electrode active material. When forming a carbon coating layer surrounding the surface of the positive electrode active material, electrical conductivity of the positive electrode active material is improved. It is preferable at that.

The carbon precursor is pitch, carbon nanofibers, sucrose, glucose, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), colloidal carbon, citric acid , Tartaric acid, glycolic acid, polyacrylic acid, adipic acid, glycine, and combinations thereof.

According to an embodiment of the present invention, a lithium battery including the cathode active material is provided.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

1 is a perspective view of a lithium battery according to an embodiment of the present invention. Referring to FIG. 1, a lithium battery 1 according to an embodiment of the present invention includes a negative electrode 3, a positive electrode 5, a separator 7 interposed between the negative electrode 3 and the positive electrode 5. And an electrode assembly 9.

In the lithium battery 1, the electrode assembly 9 is positioned in the case 15, and an electrolyte (not shown) is injected to the cathode 3, the cathode 5, and the separator 7. It is impregnated in, and the negative electrode (3) and the positive electrode (5) is produced by attaching conductive lead members (10, 13), respectively, for collecting the current generated when the battery action.

In addition, the lead members 10 and 13 serve to induce currents generated in the positive electrode 5 and the negative electrode 3 to the positive electrode terminal and the negative electrode terminal, respectively.

Although FIG. 1 illustrates a pouch-type lithium battery, the lithium battery of the present invention is not limited to the above shape, and any shape capable of operating as a battery may be possible.

The positive electrode 5 is manufactured using a positive electrode active material according to an embodiment of the present invention. The positive electrode 5 is prepared by mixing a positive electrode active material, a conductive agent, and a binder to prepare a composition for forming a positive electrode active material, and then applying the composition to a positive electrode current collector such as aluminum foil and rolling.

As the binder, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropylene cellulose, diacetylene cellulose, polyvinyl chloride, polyvinylpyrrolidone, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, or polypropylene may be used. It may be, but is not limited thereto.

In addition, as the conductive agent, any battery may be used as long as it does not cause chemical change and has an electronic conductivity. Examples thereof include natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, or copper. , Metal powders such as nickel, aluminum, silver, metal fibers and the like may be used, and conductive materials such as polyphenylene derivatives may be mixed and used.

The negative electrode 3 includes a negative electrode active material, and a compound capable of reversible intercalation and deintercalation of lithium may be used as the negative electrode active material. Specific examples of the negative electrode active material may be a carbonaceous material such as artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, and the like. In addition to the carbonaceous material, a metallic compound capable of alloying with lithium, or a composite including a metallic compound and a carbonaceous material may also be used as the negative electrode active material. As a metal which can be alloyed with lithium, Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, Al alloy, etc. can be illustrated. Moreover, a metal lithium thin film can also be used as a negative electrode active material.

Like the positive electrode 5, the negative electrode 3 may be prepared by mixing a negative electrode active material, a binder, and optionally a conductive agent to prepare a composition for forming a negative electrode active material, and then applying the same to a negative electrode current collector such as copper foil. .

As the electrolyte to be charged in the lithium battery, a non-aqueous electrolyte or a known solid electrolyte may be used.

The non-aqueous electrolyte serves as a medium through which ions involved in the electrochemical reaction of the battery can move. The non-aqueous electrolyte may be a carbonate, ester, ether or ketone solvent. Examples of the carbonate solvents include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), and ethylmethyl carbonate. (EMC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc. may be used, and the ester solvent may be n-methyl acetate, n-ethyl acetate, n-propyl acetate. And the like can be used.

The separator 7 may exist between the positive electrode 5 and the negative electrode 3 according to the type of the lithium battery. As the separator 7, polyethylene, polypropylene, polyvinylidene fluoride or two or more multilayer films thereof may be used, and polyethylene / polypropylene two-layer separator, polyethylene / polypropylene / polyethylene three-layer separator, polypropylene / polyethylene Of course, a mixed multilayer film such as a polypropylene three-layer separator can be used.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following embodiments are only preferred embodiments of the present invention, and the present invention is not limited to the following embodiments.

(Manufacture of Anode Active Material)

(Example 1)

Insert the distilled water 4L to coprecipitation reactor (capacity 4L, rotational output 90W or more of the motors), iron nitrate aqueous solution, H ₃ PO ₄ total moles of an aqueous solution, and ammonia water was fed inside the reactor iron nitrate and H ₃ PO ₄ aqueous solution An aqueous iron nitrate solution was supplied at 0.6 mol / hr, and an H ₃ PO ₄ aqueous solution was supplied at 0.6 mol / hr so that the concentration was 2M. In addition, ammonia water at a concentration of 5 M / L was supplied at an appropriate flow rate so that the pH inside the reactor was maintained at 5.

While maintaining the temperature in the reactor at 50 ° C., the solution was stirred at a speed of 1000 rpm to co-precipitate iron nitrate with H ₃ PO ₄ . The average residence time of the reactants in the reactor was adjusted to a flow rate of about 24 hours. After the reaction reached steady state, iron-phosphate hydrate was continuously obtained through the overflow pipe.

The iron-phosphate hydrate obtained above was dried at 70 ° C. for 24 hours under vacuum atmosphere.

The iron-phosphate hydrate was calcined at 550 ° C. for 10 hours under a nitrogen atmosphere to obtain iron-phosphate.

The iron-phosphate and lithium carbonate (Li ₂ CO ₃ ) were mixed in a 1: 1 molar ratio, and sucrose was added in an amount of 20 parts by weight based on 100 parts by weight of iron-phosphate, and mixed. The mixture of iron-phosphate and lithium carbonate added with sucrose was calcined at 800 ° C. for 15 hours to prepare a LiFePO ₄ cathode active material powder having an olivine structure.

(Example 2)

LiFePO ₄ positive electrode active material powder having an olivine structure was prepared in the same manner as in Example 1 except that iron-phosphate hydrate was prepared at a stirring speed of 1100 rpm.

(Example 3)

LiFePO ₄ cathode active material powder having an olivine structure was prepared in the same manner as in Example 1 except that iron-phosphate hydrate was prepared at a stirring speed of 500 rpm.

(Example 4)

LiFePO ₄ positive electrode active material powder having an olivine structure was prepared in the same manner as in Example 1 except that iron-phosphate hydrate was prepared at a stirring speed of 700 rpm.

(Example 5)

LiFePO ₄ positive electrode active material powder having an olivine structure was prepared in the same manner as in Example 1 except that iron-phosphate hydrate was prepared at a stirring speed of 1500 rpm.

(Example 6)

LiFePO ₄ positive electrode active material powder having an olivine structure was prepared in the same manner as in Example 1 except that the mixture of iron-phosphate and lithium carbonate added with sucrose was calcined at 650 ° C. for 15 hours.

(Example 7)

LiFePO ₄ positive electrode active material powder having an olivine structure was prepared in the same manner as in Example 1 except that the mixture of iron-phosphate and lithium carbonate added with sucrose was calcined at 700 ° C. for 15 hours.

(Example 8)

LiFePO ₄ positive electrode active material powder having an olivine structure was prepared in the same manner as in Example 1 except that the mixture of iron-phosphate and lithium carbonate added with sucrose was calcined at 750 ° C. for 15 hours.

(Example 9)

LiFePO ₄ positive electrode active material powder having an olivine structure was prepared in the same manner as in Example 1 except that the mixture of iron-phosphate and lithium carbonate added with sucrose was calcined at 850 ° C. for 15 hours.

(Example 10)

LiFePO ₄ positive electrode active material powder having an olivine structure in the same manner as in Example 1 except that the iron nitrate aqueous solution was supplied to the reactor at 0.15 mol / hr, and the H ₃ PO ₄ aqueous solution was supplied at 0.15 mol / hr. Was prepared.

(Example 11)

LiFePO ₄ positive electrode active material powder having an olivine structure in the same manner as in Example 1 except that the iron nitrate aqueous solution was supplied to the reactor at 0.3 mol / hr, and the H ₃ PO ₄ aqueous solution was supplied at 0.3 mol / hr. Was prepared.

(Example 12)

LiFePO ₄ positive electrode active material powder having an olivine structure in the same manner as in Example 1 except that the iron nitrate aqueous solution was supplied to the reactor at 0.72 mol / hr, and the H ₃ PO ₄ aqueous solution was supplied at 0.72 mol / hr. Was prepared.

(Example 13)

LiFePO ₄ positive electrode active material powder having an olivine structure in the same manner as in Example 1 except that the iron nitrate aqueous solution was supplied to the reactor at 0.9 mol / hr, and the H ₃ PO ₄ aqueous solution was supplied at 0.9 mol / hr. Was prepared.

(Example 14)

LiFePO ₄ positive electrode active material powder having an olivine structure in the same manner as in Example 1 except that the iron nitrate aqueous solution was supplied to the reactor at 1.05 mol / hr and the H ₃ PO ₄ aqueous solution was supplied at 1.05 mol / hr. Was prepared.

(Example 15)

LiFePO ₄ positive electrode active material powder having an olivine structure in the same manner as in Example 1 except that the iron nitrate aqueous solution was supplied to the reactor at 1.2 mol / hr, and the H ₃ PO ₄ aqueous solution was supplied at 1.2 mol / hr. Was prepared.

(Manufacture of Lithium Battery)

Each of the positive electrode active material powders prepared in Examples 1 to 15, acetylene black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder were mixed at a weight ratio of 85: 7.5: 7.5 to prepare a slurry. The slurry was uniformly applied to a 20 μm thick aluminum foil, and vacuum dried at 120 ° C. to prepare a positive electrode. The prepared anode and lithium foil were used as counter electrodes, and a porous polyethylene membrane (manufactured by Celgard ELC, Celgard 2300, thickness: 25 μm) was used as a separator, and ethylene carbonate and diethyl carbonate were 1: 1 in volume ratio. A coin battery was prepared using a liquid in which LiPF ₆ was dissolved at a concentration of 1 M in a mixed solvent as an electrolyte.

(Scanning Electron Microscopy of Prepared Iron-Phosphate, and Cathode Active Material Powder)

The iron-phosphate prepared in Example 1 was observed with a scanning electron microscope (SEM, JSM 6400, JEOL), and the results are shown in FIG. In addition, the olivine-type positive electrode active material powder prepared according to Example 1 was observed with a scanning electron microscope, and the results are shown in FIG. 3.

Referring to FIG. 2, it can be seen that the iron-phosphate prepared in Example 1 has a particle diameter within 0.5 to 2 μm. In addition, referring to FIG. 3, it can be seen that the positive electrode active material powder prepared according to Example 1 has a particle diameter of 0.5 to 3㎛.

The iron-phosphate prepared in Example 2 was observed with a scanning electron microscope, the results are shown in FIG. In addition, the olivine-type positive electrode active material powder prepared according to Example 2 was observed with a scanning electron micrograph, and the results are shown in FIG. 5.

Referring to FIG. 4, it can be seen that the iron-phosphate prepared in Example 2 has a particle diameter within 2 to 5 μm. Referring to FIG. 5, it can be seen that the cathode active material powder prepared according to Example 2 has a particle diameter of 1 to 5 μm.

It was confirmed that the cathode active material powders prepared in Examples 3 to 15 also had particle diameters of 0.1 to 10 μm as a result of observing the electron microscope.

(X-rays of manufactured iron-phosphate, and cathode active material powder diffraction  analysis)

X-ray diffraction analysis (XRD, Rint-2000, manufactured by Rigaku) for the iron-phosphate prepared in Examples 1 and 2, and the olivine-type cathode active material prepared according to Examples 1, 2, and 6 to 9 ), And the results are shown in FIGS. 6 to 13, respectively.

Referring to FIGS. 6 and 7, the same peaks as those of Card No. 29-0715 of the Joint Committee on Powder Diffraction Standards (JCPDS) were shown, and thus, the materials prepared in Examples 1 and 2 were iron-phosphate. .

Referring to FIGS. 8 to 13, the same peaks as those of Card No. 40-1499 of Joint Committee on Powder Diffraction Standards (JCPDS) appear, and the cathode active materials prepared in Examples 1, 2, and 6 to 9 are LiFePO ₄ . It can be seen that it has an olivine structure.

In addition, it can be seen that as the sintering temperature increases, Fe ₂ P peaks (2 = 40.28, 44.20, and 47.29) are formed, and lithium phosphate peaks (2 = 22.32, and 23.16) are formed.

In addition, X-ray diffraction analysis was performed on the olivine-type positive electrode active materials prepared according to Examples 3 to 5 and 10 to 15, and as a result, the positive electrode active materials prepared in Examples 3 to 5 and 10 to 15 were also included. It was confirmed that LiFePO _{4 had} an olivine structure.

(Measurement of characteristics of manufactured lithium battery)

Each coin cell manufactured using the positive electrode active material powders prepared in Examples 1 to 15 was subjected to an electrochemical analysis apparatus (Toscat 3100U, manufactured by Toyo System Co., Ltd.) at a temperature range of 2.5 V to 4.3 V at 30 ° C. The charge and discharge experiments were carried out at a current density of 15 mA g ⁻¹ . The capacity of each coin battery prepared using the positive electrode active material powders prepared in Examples 1, 2, and 6 to 8 is summarized in Table 1 below.

In addition, the particle diameters and tap densities of the positive electrode active materials prepared in Examples 1, 2, and 6 to 8 are also summarized in Table 1.

TABLE 1

Capacity (mAh / g) Particle size (㎛) Tap density (g / cm ³ ) Example 1 150 0.5 to 5 0.9 to 1.2 Example 2 138 0.2 to 2 0.8 to 1.1 Example 6 144 0.5 to 3 0.8 to 1.2 Example 7 148 0.5 to 3 0.9 to 1.2 Example 8 145 1 to 5 1.15 to 1.24

 Referring to Examples 1, 2, and 6 to 8 of Table 1, when the stirring speed in the reactor is the same, it can be seen that the capacity of the coin battery including the positive electrode active material prepared at a sintering temperature of 800 ℃ is the best. have.

In addition, a capacity graph of a battery obtained by performing a charge / discharge test on a coin battery manufactured using the cathode active material powder prepared in Example 1 is shown in FIG. 14.

Referring to FIG. 14, since the charge and discharge graph has a flat surface, a charge and discharge graph of a battery including a cathode active material having a typical olivine structure is shown, and the discharge capacity is 150 mAh / g.

In addition, a capacity graph of a battery obtained by performing a rate characteristic test on a coin battery manufactured using the cathode active material powder prepared in Example 1 is shown in FIG. 15. Referring to Figure 15, it can be seen that very good capacity of more than 70% at 10C compared to 0.1C.

In addition, the particle sizes and tap densities of the positive electrode active material powders prepared in Examples 3 to 5 and 9 to 15, and the capacity of each coin battery manufactured using the positive electrode active material powders were also described in Examples 1, 2, and 6 above. Similar to the case of 8 to 8.

All simple modifications or changes of the present invention can be easily carried out by those skilled in the art and all such modifications or changes can be seen to be included in the scope of the present invention.

The positive electrode active material according to the embodiment of the present invention has excellent crystallinity and high energy density. In addition, according to the method for manufacturing a cathode active material according to an embodiment of the present invention, a cathode active material having a uniform size and shape of particles may be manufactured.

Claims (28)

Core material; And a carbon coating layer surrounding the core material, The core material is represented by the following formula (1), the particle size is 0.1㎛ to 10㎛, tap density is 0.5 to 2.0g / cm ³ , the thickness of the carbon coating layer is an olivine-type positive electrode active material for lithium batteries. [Formula 1] Li _x M _y M ' _z XO _4-w B _w Wherein M and M 'are independently of each other consisting of Fe, Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof Is an element selected from the group, X is an element selected from the group consisting of P, As, Bi, Sb, Mo, and combinations thereof, B is an element selected from the group consisting of F, S, and combinations thereof 0 <x≤1, 0 <y≤1, 0 <z≤1, 0 <x + y + z≤2, and 0≤w≤0.5.) The method of claim 1, The core material has a particle diameter of 0.2㎛ to 8㎛, tap density of 0.7g / cm ³ to 1.6g / cm ³ olivine-type positive electrode active material for a lithium battery. The method of claim 1, The core material is an olivine-type positive electrode active material for a lithium battery that is selected from the group consisting of the following formula (2), (3), and combinations thereof. [Formula 2] LiFe _{1 - a} A _a PO ₄ Wherein A is an element selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof, 0 ≤ a ≤ 1) [Formula 3] Li _{1 - a} A _a FePO ₄ Wherein A is an element selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof, 0 ≤ a <1) The method of claim 1, The core material is an olivine-type positive electrode active material for a lithium battery that is selected from the group consisting of the following formula (4), (5), and combinations thereof. [Formula 4] LiFe _{1 - a} A _a PO _{4 - z} B _z Wherein A is an element selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof, and B Is an element selected from the group consisting of F, S, and a combination thereof, 0 ≦ a ≦ 1, and 0.01 ≦ z ≦ 0.5.) [Formula 5] Li _{1 - a} A _a FePO _{4 - z} B _z Wherein A is an element selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof, and B Is an element selected from the group consisting of F, S, and a combination thereof, wherein 0 ≦ a <1, 0.01 ≦ z ≦ 0.5.) delete M-containing solution in the reactor, where M is Fe, Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, and combinations thereof An X-containing solution (wherein X is an element selected from the group consisting of P, As, Bi, Sb, Mo, and combinations thereof), and a pH adjusting agent, Mixing at 1500 rpm to produce an MX containing hydrate; Vacuum drying the M-X-containing hydrate followed by primary firing to prepare an M-X precursor; And Mixing the M-X precursor with a lithium-containing compound and then calcining to prepare a cathode active material Method for producing an olivine-type positive electrode active material for a lithium battery comprising a. The method of claim 6, The M-containing solution is a method for producing an olivine-type positive electrode active material for a lithium battery that is supplied to the reactor at a rate of 0.03 to 1.2 mol / h. The method of claim 6, The X-containing solution is a method for producing an olivine-type positive electrode active material for a lithium battery that is supplied to the reactor at a rate of 0.03 to 1.2 mol / h. The method of claim 6, The pH adjusting agent is a method for producing an olivine-type positive electrode active material for a lithium battery that is supplied to maintain the pH in the reactor to 1.5 to 9. The method of claim 6, The mixing is a method for producing an olivine-type positive electrode active material for a lithium battery that is carried out at 800 to 1200rpm. The method of claim 6, The M-containing solution is prepared by dissolving the M-containing compound in a solvent selected from the group consisting of water, methanol, ethanol, isopropyl alcohol, and combinations thereof. The method of claim 11, The M-containing compound is acetate containing acetate, nitrate, sulfate, carbonate, citrate, phthalate, perchlorate, acetylacetonate (acetylacetonate), acrylate, formate, oxalate, halide, oxyhalide, boride, oxide, sulfide, fur Olivine-type positive electrode active material for lithium batteries, which is selected from the group consisting of oxides, alkoxides, hydroxides, ammonium, acetylacetone, hydrates thereof, and combinations thereof Method of preparation. The method of claim 11, The M-containing compound is iron ethylene diammonium sulfate (Iron ethylenediammonium sulfate), titanium bis (ammonium lactato) dihydroxide, manganese monoperoxyphthalate (Magnesium monoperoxyphthalate), aluminum phenoxide (Aluminum phnoxide), boric acid, boron trifluoride diethyl etherate, boron trifluoride-propanol, hydrates thereof, and combinations thereof The manufacturing method of the olivine-type positive electrode active material for lithium batteries which is chosen from the group. The method of claim 6, The X-containing solution is prepared by dissolving an X-containing compound in a solvent selected from the group consisting of water, methanol, ethanol, isopropyl alcohol, and combinations thereof. The method of claim 14, The X-containing compound is acetate containing acetate, nitrate, sulfate, citrate, perchlorate, halide, oxyhalide, oxide ), Sulfide, alkoxide, hydrates thereof, and combinations thereof, the method for producing an olivine-type positive electrode active material for a lithium battery. The method of claim 14, The X-containing compound is selected from the group consisting of phosphoric acid (Phosporic acid), bismuth neodecanoate, hydrates thereof, and combinations thereof. The method of claim 6, The pH adjusting agent is a method for producing an olivine-type positive electrode active material for a lithium battery that is selected from the group consisting of ammonia aqueous solution, carbon dioxide gas, a compound containing an OH group, and combinations thereof. The method of claim 6, The step of preparing the M-X-containing hydrate is a method for producing an olivine-type positive electrode active material for a lithium battery that is carried out at a temperature of 30 to 70 ℃. The method of claim 6, The step of preparing the M-X-containing hydrate is a method for producing an olivine-type positive electrode active material for a lithium battery will be carried out for 12 to 24 hours. The method of claim 6, The primary firing is a method for producing an olivine-type positive electrode active material for a lithium battery that is carried out at a temperature of 450 to 600 ℃. The method of claim 6, The primary firing is a method for producing an olivine-type positive electrode active material for a lithium battery that is carried out for 5 to 20 hours. The method of claim 6, Wherein said lithium-containing compound is selected from the group consisting of lithium hydroxide, lithium fluoride, lithium nitrate, lithium carbonate, lithium acetate, hydrates thereof, and combinations thereof. The method of claim 6, The secondary firing is a method for producing an olivine-type positive electrode active material for lithium batteries that is carried out at a temperature of 650 to 800 ℃. The method of claim 6, The secondary firing is a method for producing an olivine-type positive electrode active material for a lithium battery that is carried out for 10 to 24 hours. The method of claim 6, The primary firing and the secondary firing is a method for producing an olivine-type positive electrode active material for a lithium battery, which is made in an atmosphere selected from the group consisting of a reducing atmosphere, an inert atmosphere, and a combination thereof. The method of claim 6, After mixing the M-X precursor and the lithium-containing compound, the method of manufacturing an olivine-type positive electrode active material for a lithium battery further comprising the step of adding a carbon precursor. The method of claim 26, The carbon precursor is pitch, carbon nanofibers, sucrose, glucose, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), colloidal carbon, citric acid , Tartaric acid, glycolic acid, polyacrylic acid, adipic acid, glycine, and a combination thereof. A lithium battery comprising the positive electrode active material according to any one of claims 1 to 4.

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