KR20080093779A - Manufacturing method of negative electrode active material for lithium secondary batteries and lithium secondary battery comprising negative electrode active material prepared according to the method - Google Patents

Abstract

The present invention relates to a method for producing a negative electrode active material for a lithium secondary battery and a lithium secondary battery including a negative electrode active material prepared according to the method. The method includes preparing a mixture by mixing a lithium raw material, a vanadium raw material, and optionally an M-containing compound, and reducing and calcining the mixture in a sealed reactor to prepare a negative electrode active material of Formula 1 below. .

[Formula 1]

Li _{1 + x} V _{1 -X- y} M _y O _{2 + z}

In Formula 1, 0.01 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.3, −0.2 ≦ z ≦ 0.2, and M is composed of transition metals other than vanadium, alkali metals, alkaline earth metals, semimetals, and combinations thereof Element selected from the group.)

Lithium vanadium oxide, negative electrode active material, silicon tube, sealing, vacuum, lithium volatilization

Description

TECHNICAL FIELD OF PREPARING NEGATIVE ACTIVE MATERIAL FOR RECHARGEABLE LITHIUM BATTERY AND RECHARGEABLE LITHIUM BATTERY INCLUDING NEGATIVE ACTIVE MATERIAL PREPARED THEREFROM

1 is a flowchart illustrating a method of manufacturing a negative active material for a rechargeable lithium battery according to one embodiment of the present invention.

2 is a view schematically showing the structure of a lithium secondary battery of the present invention.

[Industrial use]

The present invention relates to a method for producing a negative electrode active material for a lithium secondary battery, and a lithium secondary battery including a negative electrode active material prepared according to the method, and more particularly, to a method for producing a negative electrode active material for lithium secondary batteries having excellent capacity characteristics and lifetime characteristics. It relates to a lithium secondary battery comprising a negative electrode active material prepared according to the method.

[Prior art]

Lithium secondary batteries, which are in the spotlight as power sources of recent portable small electronic devices, exhibit high energy density by showing a discharge voltage that is twice as high as that of a battery using an alkaline aqueous solution using an organic electrolyte solution.

Examples of the positive electrode active material of a lithium secondary battery include lithium and a transition metal having a structure capable of intercalating lithium, such as LiCoO ₂ , LiMn ₂ O ₄ , and LiNi _{1- x} Co _x O ₂ (0 <x <1). Oxides were mainly used.

As the negative electrode active material, various types of carbon-based materials including artificial graphite, natural graphite, and hard carbon capable of inserting and desorbing lithium have been applied. In the carbon series, graphite has a low discharge voltage of -0.2V compared to lithium, and a battery using graphite as a negative electrode active material exhibits a high discharge voltage of 3.6V, providing an advantage in terms of energy density of a lithium battery and providing excellent reversibility. It is the most widely used to ensure the long life of the lithium secondary battery. However, the graphite active material has a problem of low capacity in terms of energy density per unit volume of the electrode plate due to the low graphite density (theoretical density of 2.2 g / cc) in the production of the electrode plate, and side reaction with the organic electrolyte used at high discharge voltage is likely to occur. There is a risk of fire or explosion due to battery malfunction or overcharging.

In order to solve this problem, oxide cathodes have recently been developed. The amorphous tin oxide researched and developed by FUJIFILM exhibits a high capacity of 800 mAh / g per weight, but has a fatal problem with an initial irreversible capacity of about 50%, and has a discharge potential of 0.5 V or more and an amorphous characteristic unique overall soft voltage profile. (smooth voltage profile) has a problem that is difficult to be implemented as a battery. In addition, incidental problems such as reduction of some tin oxides from oxides to tin metals due to charging and discharging are also seriously occurring, making it more difficult to use them in batteries.

In addition, Japanese Patent Laid-Open No. 2002-216753 describes Li _a Mg _b VO _c (0.05 ≦ a ≦ 3, 0.12 ≦ _b ≦ 2, 2 ≦ 2c-a-2b ≦ 5) as an oxide cathode. Further, in the Japanese Battery discussion yojijip number 3B05 2002 years been published for a lithium secondary battery negative electrode characteristics of the _{Li 1 .1 V 0 .9 O 2} .

However, the oxide negative electrode does not yet exhibit satisfactory battery performance, and research on it is ongoing.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for producing a negative electrode active material for a lithium secondary battery having excellent capacity characteristics and lifespan characteristics.

Another object of the present invention is to provide a lithium secondary battery comprising the negative electrode active material prepared by the above-described method.

In order to achieve the above object, the present invention comprises the steps of preparing a mixture by mixing a lithium raw material, vanadium raw material, and optionally M-containing compound, and reducing the calcined mixture in a sealed reactor to the negative electrode of Formula 1 It provides a method for producing a negative electrode active material for a lithium secondary battery comprising the step of preparing an active material.

[Formula 1]

Li _{1 + x} V _{1 -x- y} M _y O _{2 + z}

In Formula 1, 0.01 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.3, −0.2 ≦ z ≦ 0.2, and M is composed of transition metals other than vanadium, alkali metals, alkaline earth metals, semimetals, and combinations thereof Element selected from the group.)

The present invention also provides a lithium secondary battery comprising a negative electrode comprising a negative electrode active material prepared according to the above method, a positive electrode including a positive electrode active material capable of reversibly intercalating and deintercalating lithium ions, and an electrolyte solution. to provide.

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

The lithium vanadium oxide (hereinafter referred to as LVO) anode active material is manufactured by grinding and mixing solid Li ₂ CO ₃ or LiOH with V ₂ O ₃ or V ₂ O ₄ , calcining, and then screening do. In general, electrochemical properties such as life characteristics and capacity characteristics of the LVO anode active material are proportional to the electrode density. Therefore, in order to improve the electrochemical properties of the LVO anode active material, the degree of mixing of lithium and vanadium, crystal structure, crystallinity, lithium and Control of variables related to electrode density, such as quantum ratio of vanadium, c / a lattice constant ratio, oxidation rate of vanadium, particle shape, and particle size, is required.

However, although the crystal structure, crystallinity, c / a lattice constant ratio, and vanadium oxide number can be controlled by the method, there is a problem in that particles are agglomerated at a high calcination temperature. In addition, it is difficult to control the ratio of lithium and vanadium, the shape of the particles, the particle size, and the like, and thus it is difficult to secure electrochemical properties and reproducibility by improving the electrode density.

In particular, the LiVMO negative electrode active material which improves the conductivity of the existing LVO negative electrode active material, the solid phase Li ₂ CO ₃ or LiOH as a lithium raw material and V ₂ O ₃ or V ₂ O ₄ as a vanadium raw material is first ground and mixed It is prepared through a complex process of calcining, to prepare a mixture of solid phase, which is then pulverized, mixed with MO ₂ and mixed, calcined, and then screened. Therefore, during such a complex process, there is a problem that it is very difficult to control the variables related to the electrode density.

On the other hand, according to the manufacturing method of the negative electrode active material for lithium secondary batteries of the present invention, the homogeneous mixing of vanadium and lithium has high reproducibility of the material, and since low-temperature firing is possible, the degree of volatilization of lithium and the degree of oxidation of vanadium can be controlled. Therefore, the negative electrode active material for lithium secondary batteries having low crystallinity and size and primary particle size, and high crystallinity can be produced.

The present invention relates to a method for producing a negative electrode active material for a lithium secondary battery, Figure 1 is a flow chart showing a method for producing the negative electrode active material.

Referring to FIG. 1, in the method of preparing a negative active material for a lithium secondary battery of the present invention represented by the following Chemical Formula 1, a step of preparing a mixture by mixing a lithium raw material, a vanadium raw material, and optionally an M-containing compound (S1) , And reducing calcination of the mixture in the sealed reactor (S2).

[Formula 1]

Li _{1 + x} V _{1 -x- y} M _y O _{2 + z}

In Formula 1, 0.01 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.3, −0.2 ≦ z ≦ 0.2, and M is composed of transition metals other than vanadium, alkali metals, alkaline earth metals, semimetals, and combinations thereof Element selected from the group.)

First, a lithium raw material, a vanadium raw material, and optionally a M-containing compound are mixed to prepare a mixture (S1).

Representative examples of the lithium raw material include LiX (X is F, Cl, Br, or I), LiC ₂ O ₂ H ₃ , Li ₂ C ₂ O ₄ , LiCOOH, Li ₂ CO ₃ , LiOH, LiNO ₃ , Li ₂ SO ₄ , and those selected from the group consisting of, and combinations thereof, but is not limited thereto.

Representative examples of the vanadium source material is _{VOCl 3, VOCl 2, VCl 3} , VCl 4, V 2 O 3, VOSO ₄ , V ₂ O ₄ , V ₂ O ₅ , NH ₄ VO ₃ , And hydrates thereof, and combinations thereof, preferably VOCl ₃ , V ₂ O ₃ , VOSO ₄ , VCl ₃ , VCl ₄ , VOCl ₂ , and hydrates thereof, and their It may be selected from the group consisting of a combination, but is not limited thereto.

In addition, M-containing compounds may optionally be further added depending on the desired product. The M-containing compound may be selected from the group consisting of M-containing hydroxides, hydrates, oxides, nitrides, nitrates, carbonates, sulfates, chlorides, and combinations thereof, and representative examples thereof include sulfur oxides and nitride oxides containing M. It may be selected from the group consisting of, and combinations thereof. M of the M-containing compound is an element having an ionic radius (0.78 kV) similar to vanadium (III, IV), and may be an octahedral composite structure, or an element having an electronic structure similar to vanadium (III, IV). . Representative examples of M include transition metals other than vanadium, alkali metals, alkaline earth metals, and semimetals (having intermediate properties between nonmetals and metals, typically bismuth (Bi), antimony (Sb), and arsenic (As). , Silicon (Si), germanium (Ge), and the like), and an element selected from the group consisting of a combination thereof. The M may be substituted with a homogeneous distribution in the lithium vanadium oxide anode active material to improve structural stability of the active material.

The lithium raw material, the vanadium raw material, and the M-containing compound may be appropriately mixed and used in a molar ratio between the elements of Chemical Formula 1, and preferably, may be mixed and used in the following molar ratios.

The lithium raw material and the vanadium raw material are preferably mixed and used in a molar ratio of 1: 0.99 to 1: 0.5, and more preferably mixed and used in a molar ratio of 1: 0.9 to 1: 0.7. Within this range, it is preferable to obtain a negative electrode active material having a uniform composition, and when out of the above range, a phase or other phase whose composition is not uniform may be formed, which is not preferable.

In addition, the lithium raw material and the M-containing compound are preferably used in a molar ratio of 1: 0 to 1: 0.5, and more preferably in a molar ratio of 1: 0.05 to 1: 0.3. Within this range, there is an advantage that a uniform phase is formed, which is preferable.

Subsequently, the mixture is reduced and calcined in a sealed reactor to prepare a negative electrode active material (S2).

The reducing calcination step is carried out by putting the mixture in the reactor, sealing the reactor, and then reducing calcination of the reactor at 400 to 1300 ° C. for 0.5 to 12 hours. The reduction calcination process may be carried out at 500, 600, 700, 800, 900, 1000, 1100, or 1200 ° C. If the temperature is less than 400 ℃ can not be made of a material phase of the correct composition is not preferable, if the temperature exceeds 1300 ℃ may not maintain the atmosphere of sealing is not preferred. In addition, in the above time range, there is an advantage that a powder having a suitable composition can be obtained, which is preferable.

In addition, the reduction calcination process of the present invention may be carried out by heat treatment first at 400 to 700 ℃ for 0.5 to 12 hours, and second heat treatment at 700 to 1300 ℃ for 0.5 to 12 hours. Within the above temperature and time ranges, an atomized anode active material having a small particle size and high crystallinity can be obtained. As described above, when the reduction and calcination processes are carried out in the first and second stages, the particle size of the negative electrode active material can be adjusted to increase the electrode density. Therefore, the life characteristics and capacity characteristics of the negative electrode including the same may be improved.

The reactor may be made of a material selected from the group consisting of quartz (Quartz), silicon, alumina, mullite, and a combination thereof, preferably made of quartz or alumina. In addition, the reactor is not limited to the form, but may be representatively used in the form of a tube.

In addition, the sealed reactor may be filled with an inert gas such as argon, hydrogen, nitrogen, or may be in a vacuum state.

After the reduction calcination process, a negative electrode active material of Formula 1 may be prepared.

[Formula 1]

Li _{1 + x} V _{1 -x- y} M _y O _{2 + z}

(In the formula 1, 0.01 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.3, -0.2 ≤ z ≤ 0.2, M is a group consisting of transition metals other than vanadium, alkali metals, alkaline earth metals, semimetals and combinations thereof Is an element selected from.)

In general, in order for the lithium vanadium-based negative active material to be applied as a negative electrode material, the amount of lithium must be higher than that of vanadium, but since lithium metal is highly volatile, there is a problem of volatilization during the calcination process. However, in the method for producing the negative electrode active material of the present invention, since the reduction calcination process is performed in the sealed reactor, the volatilization of lithium can be suppressed and the oxidation number of vanadium can be controlled.

According to the manufacturing method of the negative electrode active material for lithium secondary batteries of this invention, the volatilization degree of lithium can be suppressed, the oxidation number of vanadium can be controlled, and the reproducible lithium vanadium oxide negative electrode active material can be manufactured. Therefore, it is possible to manufacture a negative electrode active material having excellent electrochemical characteristics and fine size, and is easy to manufacture a negative electrode for a lithium secondary battery having excellent life characteristics and capacity characteristics through electrode density improvement.

A lithium secondary battery according to another embodiment of the present invention includes a negative electrode, a positive electrode, and an electrolyte.

The negative electrode includes a current collector and a negative electrode active material layer formed on the current collector, and the negative electrode active material layer includes a negative electrode active material.

The negative electrode active material is the same as described above.

The negative electrode may be prepared by mixing the negative electrode active material, a binder, and optionally a conductive agent in a solvent to prepare a composition for forming a negative electrode active material layer, and then applying the composition to a negative electrode current collector. Since such an electrode manufacturing method is well known in the art, detailed description thereof will be omitted.

As the binder, the negative electrode active material particles adhere well to each other, and the negative electrode active material adheres well to the current collector. Examples thereof include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropylene cellulose, diacetylene cellulose, and polyvinyl. Chloride, polyvinylpyrrolidone, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene or polypropylene, and the like, may be used, but is not limited thereto.

The conductive agent is used to impart conductivity, and any battery can be used as long as it is an electronic conductive material without causing chemical change in the battery to be constructed. Examples thereof include natural graphite, artificial graphite, carbon black, acetylene black, and ketjen black. , Metal powders such as carbon fiber, copper, nickel, aluminum, silver, or metal fibers, and the like, and also conductive materials such as polyphenylene derivatives can be mixed and used.

N-methylpyrrolidone may be used as the solvent, but is not limited thereto.

The cathode current collector may be selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with conductive metal, and combinations thereof. have.

The positive electrode includes a current collector and a cathode active material layer formed on the current collector. As the cathode active material, a compound (lithiated intercalation compound) capable of reversible intercalation and deintercalation of lithium may be used. Specifically, at least one of a complex oxide of metal and lithium selected from cobalt, manganese, nickel, and combinations thereof may be used, and more preferably, a compound represented by any one of the following Chemical Formulas 2 to 25 may be used. have:

[Formula 2]

Li _a A _{1 - b} B _b D ₂

(Wherein 0.95 ≦ a ≦ 1.1, and 0 ≦ b ≦ 0.5)

[Formula 3]

Li _a E _{1 - b} B _b O _{2 - c} F _c

(Wherein 0.95 ≦ a ≦ 1.1, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05)

[Formula 4]

LiE _{2 - b} B _b O _{4 - c} F _c

(Wherein 0 ≦ b ≦ 0.5 and 0 ≦ c ≦ 0.05)

[Formula 5]

Li _a Ni _{1 -b- c} Co _b BcD _α

(Wherein 0.95 ≦ a ≦ 1.1, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, and 0 <α ≦ 2)

[Formula 6]

Li _a Ni _{1 -b- c} Co _b B _c O _{2 -α} F _α

(Wherein 0.95 ≦ a ≦ 1.1, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, and 0 <α <2)

[Formula 7]

Li _a Ni _{1 -b- c} Co _b B _c O _{2 -α} F ₂

(Wherein 0.95 ≦ a ≦ 1.1, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, and 0 <α <2)

[Formula 8]

Li _a Ni _{1 -b- c} Mn _b B _c D _α

(Wherein 0.95 ≦ a ≦ 1.1, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, and 0 <α ≦ 2)

[Formula 9]

Li _a Ni _{1 -b- c} Mn _b B _c O _{2 -α} F _α

(Wherein 0.95 ≦ a ≦ 1.1, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, and 0 <α <2)

[Formula 10]

Li _a Ni _{1 -b- c} Mn _b B _c O _{2 -α} F ₂

(Wherein 0.95 ≦ a ≦ 1.1, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, and 0 <α <2)

[Formula 11]

Li _a Ni _b E _c G _d O ₂

(Wherein 0.90 ≦ a ≦ 1.1, 0 ≦ b ≦ 0.9, 0 ≦ c ≦ 0.5, and 0.001 ≦ d ≦ 0.1.)

[Formula 12]

Li _a Ni _b Co _c Mn _d GeO ₂

(Wherein 0.90 ≦ a ≦ 1.1, 0 ≦ b ≦ 0.9, 0 ≦ c ≦ 0.5, 0 ≦ d ≦ 0.5, and 0.001 ≦ e ≦ 0.1).

[Formula 13]

Li _a NiG _b O ₂

(Wherein 0.90 ≦ a ≦ 1.1 and 0.001 ≦ b ≦ 0.1)

[Formula 14]

Li _a CoG _b O ₂

(Wherein 0.90 ≦ a ≦ 1.1 and 0.001 ≦ b ≦ 0.1)

[Formula 15]

Li _a MnG _b O ₂

(Wherein 0.90 ≦ a ≦ 1.1 and 0.001 ≦ b ≦ 0.1)

[Formula 16]

Li _a Mn ₂ G _b O ₄

(Wherein 0.90 ≦ a ≦ 1.1 and 0.001 ≦ b ≦ 0.1)

[Formula 17]

QO ₂

[Formula 18]

QS ₂

[Formula 19]

LiQS ₂

[Formula 20]

V ₂ O ₅

[Formula 21]

LiV ₂ O ₅

[Formula 22]

LiIO ₂

[Formula 23]

LiNiVO ₄

[Formula 24]

Li _(3-f) J ₂ (PO ₄ ) ₃ (0 ≤ f ≤ 3)

[Formula 25]

Li _(3-f) Fe ₂ (PO ₄ ) ₃ (0 ≤ f ≤ 2)

In Chemical Formulas 2 to 25, A is selected from the group consisting of Ni, Co, Mn, and combinations thereof;

B is selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements and combinations thereof;

D is selected from the group consisting of O, F, S, P, and combinations thereof;

E is selected from Co, Mn, and combinations thereof;

F is selected from the group consisting of F, S, P, and combinations thereof;

G is Al or an element selected from the group consisting of Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof;

Q is selected from the group consisting of Ti, Mo, Mn, and combinations thereof;

I is selected from the group consisting of Cr, V, Fe, Sc, Y, and combinations thereof;

J is selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, and combinations thereof.

Of course, what has a coating layer on the surface of this compound can also be used, or the compound and the compound which have a coating layer can also be used in mixture. The coating layer may include at least one coating element compound selected from the group consisting of oxides of the coating elements, hydroxides, oxyhydroxides of the coating elements, oxycarbonates of the coating elements and hydroxycarbonates of the coating elements. The compounds constituting these coating layers may be amorphous or crystalline. As the coating element included in the coating layer, Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr or a mixture thereof may be used. The coating layer forming process may use any coating method as long as it does not adversely affect the physical properties of the positive electrode active material by using such elements in the compound (for example, spray coating, dipping, etc.). Details that will be well understood by those in the field will be omitted.

Like the negative electrode, the positive electrode may be prepared by mixing the positive electrode active material, the binder, and the conductive agent in a solvent to prepare a composition for forming a positive electrode active material layer, and then applying the composition for forming the positive electrode active material layer to a positive electrode current collector. .

Aluminum may be used as the anode current collector, and N-methylpyrrolidone may be used as the solvent, but the cathode current collector and the solvent are not limited thereto.

Since such an electrode manufacturing method is well known in the art, detailed description thereof will be omitted.

As the conductive agent, any battery can be used as long as it is an electronic conductive material without causing chemical change, and examples thereof include natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, copper, nickel, and aluminum. Metal powders, such as silver, metal fiber, etc. can be used, and conductive materials, such as a polyphenylene derivative, can be used 1 type or in mixture of 1 or more types.

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.

N-methylpyrrolidone may be used as the solvent, but is not limited thereto.

In the nonaqueous electrolyte secondary battery of the present invention, the nonaqueous electrolyte includes a nonaqueous organic solvent and a lithium salt.

The non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the cell can move.

As the non-aqueous organic solvent, a carbonate-based, ester-based, ether-based, ketone-based, alcohol-based, or aprotic solvent may be used. As the carbonate solvent, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) and the like can be used, and the ester solvent is n-methyl acetate, n-ethyl acetate, n-propyl acetate, dimethyl Acetate, methylpropionate, ethylpropionate, γ-butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, and the like can be used. As the ether, dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, etc. may be used, and cyclohexanone may be used as the ketone solvent. In addition, ethyl alcohol, isopropyl alcohol, etc. may be used as the alcohol solvent, and the aprotic solvent may be R-CN (R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms. Amides such as nitriles, dimethylformamide, dioxolanes such as 1,3-dioxolane, sulfolanes, and the like.

The non-aqueous organic solvent may be used alone or in combination of one or more, and the mixing ratio in the case of mixing one or more may be appropriately adjusted according to the desired battery performance, which is widely understood by those skilled in the art. Can be.

In the case of the carbonate solvent, it is preferable to use a mixture of a cyclic carbonate and a chain carbonate. In this case, the cyclic carbonate and the chain carbonate may be mixed and used in a volume ratio of 1: 1 to 1: 9, so that the performance of the electrolyte may be excellent.

The non-aqueous organic solvent of the present invention may further include an aromatic hydrocarbon organic solvent in the carbonate solvent. In this case, the carbonate solvent and the aromatic hydrocarbon organic solvent may be mixed in a volume ratio of 1: 1 to 30: 1.

As the aromatic hydrocarbon organic solvent, an aromatic hydrocarbon compound represented by Chemical Formula 26 may be used.

[Formula 26]

(In Formula 26, R _{1 To} R ₆ are each independently selected from the group consisting of hydrogen, halogen, alkyl group of 1 to 10 carbon atoms, haloalkyl group and combinations thereof.)

Preferred aromatic hydrocarbon organic solvents are benzene, fluorobenzene, 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 1,2,3-trifluorobenzene , 1,2,4-trifluorobenzene, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4- dichlorobenzene, 1,2,3-trichlorobenzene, 1,2, 4-trichlorobenzene, iodobenzene, 1,2-dioodobenzene, 1,3-dioodobenzene, 1,4-dioiobenzene, 1,2,3-triiodobenzene, 1,2,4 -Triiodobenzene, toluene, fluorotoluene, 1,2-difluorotoluene, 1,3-difluorotoluene, 1,4-difluorotoluene, 1,2,3-trifluorotoluene, 1,2,4-trifluorotoluene, chlorotoluene, 1,2-dichlorotoluene, 1,3-dichlorotoluene, 1,4-dichlorotoluene, 1,2,3-trichlorotoluene, 1,2,4 -Trichlorotoluene, iodotoluene, 1,2-dioodotoluene, 1,3-diodotoluene, 1,4-diao Toluene, to which 1,2,3-tree-iodo toluene, 1,2,4-iodo toluene, xylene, and selected from the group consisting of.

The non-aqueous electrolyte may further include a life improving additive such as vinylene carbonate or fluoroethylene carbonate in order to improve battery life. In the case of further using such life improving additives, the amount thereof can be properly adjusted. The lithium salt is a substance that dissolves in an organic solvent and acts as a source of lithium ions in the battery to enable the operation of a basic lithium secondary battery and to promote the movement of lithium ions between the positive electrode and the negative electrode. Representative examples of such lithium salts are LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (SO ₂ C ₂ F ₅ ) ₂ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiClO ₄ , LiAlO ₄ , LiAlCl ₄ , LiN (C _x F _{2x +1} SO ₂ ) (C _y F _{2y +1} SO ₂ ), where x and y are natural numbers, LiCl, LiI, and lithium bisoxal One or more selected from the group consisting of lithium bisoxalate borate is included as a supporting electrolytic salt.

The concentration of the lithium salt is preferably used within the range of 0.1 to 2.0M. If the concentration of the lithium salt is less than 0.1M, the conductivity of the electrolyte is lowered, the performance of the electrolyte is lowered, if it exceeds 2.0M there is a problem that the mobility of the lithium ion is reduced by increasing the viscosity of the electrolyte.

The separator may exist between the positive electrode and the negative electrode according to the type of the lithium secondary battery. As the separator, 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 / poly It goes without saying that a mixed multilayer film such as a propylene three-layer separator can be used.

An example of the lithium secondary battery of the present invention having the above-described configuration is shown in FIG. 2. 2 shows a cathode 2, an anode 3, a separator 4 disposed between the cathode 2 and an anode 3, the cathode 2, the anode 3, and the separator 4. The lithium secondary battery 1 which consists of the electrolyte solution impregnated in, the battery container 5, and the sealing member 6 which encloses the battery container 5 as a main part is shown.

Of course, the lithium secondary battery of the present invention is not limited to this formation, and any shape such as a square, a pouch, etc., including the negative electrode active material of the present invention and capable of operating as a battery, is of course possible.

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

(Example 1)

A mixture was prepared by mixing Li ₂ CO ₃ , V ₂ O ₃ , and Cr ₂ (SO 4) ₃ H ₂ O such that the molar ratio of lithium, vanadium, and chromium was 1.1: 0.9: 0.1. The mixture was sealed into a silicone tube of the vacuum condition, by reducing calcination at 700 ℃ to prepare a _{Li 1 .1 (V, Cr)} 1 O 2 negative active material.

(Example 2)

A negative active material for a lithium secondary battery was prepared in the same manner as in Example 1 except that Li ₂ CO ₃ was changed to Li ₂ C ₂ O ₄ .

(Example 3)

A negative electrode active material for a lithium secondary battery was prepared in the same manner as in Example 1 except that Li ₂ CO ₃ was changed to LiCOOH.

(Example 4)

Except for changing Li ₂ CO ₃ to LiOH was carried out in the same manner as in Example 1 to prepare a negative electrode active material for a lithium secondary battery.

(Example 5)

Except for changing Li ₂ CO ₃ to LiNO _{3 It} was carried out in the same manner as in Example 1 to prepare a negative electrode active material for a lithium secondary battery.

(Example 6)

A negative electrode active material for a lithium secondary battery was prepared in the same manner as in Example 1 except that Li ₂ CO ₃ was changed to Li ₂ SO ₄ .

(Example 7)

Li ₂ CO ₃ to Li ₂ SO ₄ Except for changing to a hydrate it was carried out in the same manner as in Example 1 to prepare a negative electrode active material for a lithium secondary battery.

(Example 8)

A negative active material for a lithium secondary battery was prepared in the same manner as in Example 1 except that V ₂ O ₃ was changed to VOSO ₄ .

(Example 9)

The V ₂ O ₃ VOSO ₄ Except for changing to a hydrate it was carried out in the same manner as in Example 1 to prepare a negative electrode active material for a lithium secondary battery.

(Example 10)

A negative active material for a lithium secondary battery was prepared in the same manner as in Example 1 except that V ₂ O ₃ was changed to VOCl ₃ .

(Example 11)

V ₂ O ₃ to VOCl ₃ Except for changing to a hydrate it was carried out in the same manner as in Example 1 to prepare a negative electrode active material for a lithium secondary battery.

(Example 12)

A mixture was prepared by mixing Li ₂ CO ₃ , V ₂ O ₃ , and Cr ₂ (SO 4) ₃ H ₂ O to a molar ratio of lithium, vanadium, and chromium of 1.1: 0.9: 0.1. To insert sealing the mixture in a silicone tube filled with an argon gas, by reducing calcination at 700 ℃ to prepare a _{Li 1 .1 (V, Cr)} 1 O 2 negative active material.

(Comparative Example 1)

LiOH and the V ₂ O ₃ 1.1: 0.45 were mixed in a ratio of grinding, which was manufactured and then subjected to the calcination step of heat treatment at _{900 ℃, Li 1 .1 V 0} .9 O 2 negative active material through the screening.

Discharge capacity and initial reversible efficiency measurement

After preparing a coin cell using the negative electrode active material prepared according to Examples 1 to 12, and Comparative Example 1, each coin cell was charged and discharged at 0.1C once to perform a chemical conversion process, and charged and discharged at 0.5C Was carried out.

For the coin cell, the discharge capacity at the time of one charge and discharge (meaning that the charge and discharge was performed once after battery formation) and the initial reversible efficiency were measured, and the results of Example 1 and Comparative Example 1 were shown in the following table. 1 is shown.

TABLE 1

Initial discharge capacity (mAh / cc) Initial Reversible Efficiency (%) Example 1 590 86 Comparative Example 1 570 83

Referring to Table 1, the coin cell using the negative electrode active material of Example 1 was superior in initial reversible efficiency compared to the coin cell using the negative electrode active material of Comparative Example 1, in particular, the initial discharge capacity of Example 1 was It was much higher than that. Therefore, it was confirmed that the negative electrode active material for a lithium secondary battery according to the manufacturing method of the present invention has excellent life characteristics and capacity characteristics. Moreover, about the coin cells of Examples 2-12, the initial reversible efficiency and initial discharge capacity of the level equivalent to Example 1 were confirmed.

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.

According to the negative electrode active material manufacturing method for a lithium secondary battery of the present invention, the negative electrode active material may improve capacity characteristics and cycle life characteristics.

Claims (12)

Preparing a mixture by mixing lithium raw material, vanadium raw material, and optionally M-containing compound; And Reducing and calcining the mixture in a sealed reactor to prepare a negative electrode active material of Formula 1 Method for producing a negative electrode active material for a lithium secondary battery comprising a. [Formula 1] Li _{1 + x} V _{1 -X- y} M _y O _{2 + z} (In the formula 1, 0.01 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.3, -0.2 ≤ z ≤ 0.2, M is a group consisting of transition metals other than vanadium, alkali metals, alkaline earth metals, semimetals and combinations thereof Is an element selected from.) The method of claim 1, The lithium raw material is LiX (X is F, Cl, Br, or I), LiC ₂ O ₂ H ₃ , Li ₂ C ₂ O ₄ , LiCOOH, Li ₂ CO ₃ , LiOH, LiNO ₃ , Li ₂ SO ₄ , and a hydrate thereof, and a combination thereof, a method for producing a negative electrode active material for a lithium secondary battery. The method of claim 1, The vanadium raw material is V0Cl ₃ , V ₂ O _{3 ,} V0SO ₄ , VCl ₃ , VCl ₄ , VOCl ₂ , V ₂ O ₄ , V ₂ O ₅ , NH ₄ VO ₃ , and hydrates thereof, and combinations thereof Method for producing a negative electrode active material for a lithium secondary battery that is selected from the group consisting of. The method of claim 1, M of the M-containing compound is selected from the group consisting of transition metals other than vanadium, alkali metals, alkaline earth metals, semimetals, and combinations thereof. The method of claim 1, The M-containing compound is a method for producing a negative electrode active material for a lithium secondary battery that is selected from the group consisting of hydroxides, hydrates, oxides, nitrides, nitrates, carbonates, sulfates, chlorides, and combinations thereof. The method of claim 1, The lithium raw material and vanadium raw material is a method of producing a negative electrode active material for a lithium secondary battery is mixed in a molar ratio of 1: 0.99 to 1: 0.5. The method of claim 1, The lithium raw material and the M-containing compound are mixed in a molar ratio of 1: 0 to 1: 0.5. The method of claim 1, The reactor is a quartz (Quartz), silicon, alumina, mullite, and a method for producing a negative electrode active material for a lithium secondary battery that is made from a group consisting of a combination thereof. The method of claim 1, The inside of the reactor is filled with an inert gas or vacuum method of producing a negative active material for a rechargeable lithium battery. The method of claim 1, The reduction calcination step is a method for producing a negative electrode active material for a lithium secondary battery that is heat-treated at 400 to 1300 ℃. The method of claim 1, The reduction calcination step is a primary heat treatment at 400 to 700 ℃, secondary heat treatment at 700 to 1300 ℃ manufacturing method of a negative electrode active material for a lithium secondary battery. A negative electrode comprising a negative electrode active material prepared according to any one of claims 1 to 11; A positive electrode including a positive electrode active material capable of reversibly intercalating and deintercalating lithium ions; And Electrolyte Lithium secondary battery comprising a.

Images