KR20220169559A - Anode active material, method for preparing the same, and rechargeable lithium battery comprising the same - Google Patents

Abstract

The present invention relates to a negative electrode active material, a manufacturing method thereof, and a lithium secondary battery including the same, wherein the negative electrode active material includes: a core including silicon-containing particles whose surface is entirely or partially coated with lithium-containing oxide particles; and a shell surrounding the core. The negative electrode active material according to the present invention is capable of stable charge/discharge behavior under high current density.

Description

Anode active material, method for preparing the same, and lithium secondary battery comprising the same {Anode active material, method for preparing the same, and rechargeable lithium battery comprising the same}

The present invention relates to a negative electrode active material, a manufacturing method thereof, and a lithium secondary battery including the same, and specifically, a negative electrode active material capable of stable charge/discharge behavior even under high current density by introducing lithium-containing oxide particles, a manufacturing method thereof, and the same It relates to a lithium secondary battery comprising

Lithium Ion Battery (LIB) has high energy density and is easy to design, so it is adopted and used as a major power supply source for mobile electronic devices. The range is getting wider.

In order to apply to new application fields, research on LIB materials having characteristics such as higher energy density and longer life is continuously required.

In particular, in the case of cathode materials, research has been conducted on various materials such as carbon, silicon, tin, and germanium.

Among them, silicon-based anode materials have received a lot of attention because they have a very high energy density compared to currently commercialized graphite anode materials.

However, the silicon-based negative electrode material has fatal disadvantages such as deterioration of electrochemical properties due to the formation of an unstable SEI layer due to side reactions between the silicon surface and the electrolyte, or crushing of the electrode material due to internal stress due to rapid volume expansion occurring during charging and discharging. has

In order to solve this problem, a lot of research has been conducted on improving reversibility on the surface through various surface treatments of silicon-based negative electrode materials, and in particular, methods of surface coating or compounding carbon materials have been widely studied.

On the other hand, various surface treatments using carbon materials required complex and expensive processes, and although some lifespan characteristics of silicon-based anode materials were improved through surface treatment using carbon materials, the ionic conductivity of silicon-based anode materials was lowered, resulting in recent demand. There was a limit to improving the output characteristics for the implementation of the high-speed charge-discharge LIB, which is increasing.

That is, since the conventional surface treatment using a carbon material proceeds with complexing with carbon without improving the low ionic conductivity of the silicon-based negative electrode material, it is difficult to reach the output characteristics required for a high-speed charge/discharge LIB.

Therefore, there is a demand for developing a technology for surface treatment of a high-capacity silicon-based negative electrode active material that suppresses the volume expansion of the silicon-based negative electrode material and at the same time improves the low ionic conductivity of the silicon-based negative electrode material.

Republic of Korea Patent Publication No. 2021-0028054 Republic of Korea Patent Publication No. 2020-0073350

Accordingly, an object of the present invention is to provide an anode active material for a high-output secondary battery capable of stable charge/discharge behavior under high current density while having high capacity and high energy density.

In addition, it is an object of the present invention to provide a manufacturing method capable of manufacturing the negative electrode active material at high efficiency and low cost.

In addition, an object of the present invention is to provide an electrode and a lithium secondary battery including the negative electrode active material.

However, the problem to be solved by the present application is not limited to the above-mentioned problem, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

One aspect of the present disclosure, a core including silicon-containing particles coated with all or part of the surface of lithium-containing oxide particles; and

Including; a shell surrounding the core,

The lithium-containing oxide is represented by Formula 1 below,

An anode active material is provided.

[Formula 1]

Li _x M _y O _z

In Formula 1,

M is at least one selected from Si, Al, Ti, Mn, Ni, Cu, V, Zr, Mn, Co, Fe, and Nb;

x>0, y>0 and 0<z≤(x+m·y)/2, where m is the oxidation number of M.

Another aspect of the present application is a composite comprising mixing and combining silicon-containing particles, a lithium precursor, a metal precursor, amorphous carbon and crystalline carbon; and

Including; heat treatment step;

The metal is at least one selected from Si, Al, Ti, Mn, Ni, Cu, V, Zr, Mn, Co, Fe and Nb,

A method for producing a negative electrode active material is provided.

Another aspect of the present application, including the negative electrode active material,

electrodes are provided.

Another aspect of the present application is a negative electrode including the negative electrode active material;

an anode positioned opposite to the cathode; and

It provides a lithium secondary battery comprising an electrolyte disposed between the negative electrode and the positive electrode.

The negative electrode active material according to the present invention has an effect of providing a high-output secondary battery capable of stable charge/discharge behavior under high current density while having high capacity and high energy density.

In addition, there is an effect of producing a negative electrode active material with high efficiency and low cost.

1 is a schematic diagram showing an anode active material having a core-shell structure according to an embodiment of the present invention.
2 is an XRD and Raman spectrum of an anode active material according to Example 1 of the present invention.
3 is scanning electron microscopy (SEM) and transmission electron microscopy (TEM) pictures of the negative electrode active material according to Example 1 of the present invention.
4 is an energy dispersive X-ray spectroscopy (EDS) analysis picture of a cross section of an anode active material according to Example 1 of the present invention.
5 is a charge/discharge graph of a cell to which negative electrode active materials according to Example 1 and Comparative Example 1 of the present invention are applied.
6 is an impedance measurement result of a cell to which an anode active material according to Example 1 and Comparative Example 1 of the present invention is applied.
7 is a measurement result of a constant current capacity fraction in a charging process according to a change in current density (c-rate) of a cell to which an anode active material according to Example 1 and Comparative Example 1 of the present invention is applied.

The terms or words used in this specification and claims should not be construed as being limited to ordinary or dictionary meanings, and the inventors may appropriately define the concept of terms in order to explain their invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention based on the principle that there is.

Therefore, since the configuration of the embodiments described in this specification is only one of the most preferred embodiments of the present invention and does not represent all of the technical spirit of the present invention, various equivalents and modifications that can replace them at the time of the present application It should be understood that examples may exist.

In this specification, singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "comprise", "comprise" or "having" are intended to indicate that there is an embodied feature, number, step, component, or combination thereof, but one or more other features or It should be understood that the presence or addition of numbers, steps, components, or combinations thereof is not precluded.

As shown in FIG. 1 , the negative electrode active material according to one aspect of the present disclosure may include a core including silicon-containing particles coated with lithium-containing oxide particles on all or part of a surface, and a shell surrounding the core.

The lithium-containing oxide particles are coated on the surface of the silicon-containing particles of the negative active material, and may not be a coating layer in the form of a film of lithium-containing oxide particles completely covering the entire surface of the silicon-containing particles.

For example, the lithium-containing oxide particles account for 100% or less, 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 20% or less of the total surface of the silicon-containing particles, 10% or less, 5% or less may be coated, and the degree of coating may be adjusted by changing process conditions during the preparation of the negative electrode active material.

In addition, the lithium-containing oxide may be represented by Formula 1 below.

[Formula 1]

Li _x M _y Oz

In Formula 1,

M is at least one selected from Si, Al, Ti, Mn, Ni, Cu, V, Zr, Mn, Co, Fe, and Nb;

x>0, y>0 and 0<z≤(x+m·y)/2, where m is the oxidation number of M.

On the other hand, the silicon-containing particles coated on the surface of the lithium-containing oxide particles may be included in the shell in addition to the core according to a change in process conditions of the manufacturing process.

The lithium-containing oxide particles coated on the surface of the silicon-containing particles are materials having excellent rate capability and can improve high-rate charge/discharge and high-speed charge performance of the battery.

In one embodiment, the silicon-containing particles may be silicon particles, silicon oxide particles, silicon carbide particles, silicon alloy particles, or combinations thereof.

The silicon-containing particles may be represented by Formula 2 below.

[Formula 2]

SiOx (0≤x≤0.5)

In Formula 2, when x exceeds 0.5, there may be adverse effects on battery capacity and efficiency. That is, lithium ions react with oxygen to produce irreversible products such as Li ₂ O and Li-silicate (Li _x Si _y O _z ). Due to this, lithium ions that have reacted with the negative electrode material cannot return to the electrolyte or the positive electrode material and are trapped inside the negative electrode, so that capacity cannot be expressed and efficiency is also reduced.

In addition, for example, the silicon carbide may be SiC, and the silicon alloy may be, for example, a Si—Z alloy (where Z is an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, a transition metal, or a rare earth element) And one or more elements selected from combinations thereof, but not Si).

The average particle diameter (D50) of the silicon-containing particles may be 50 to 1,000 nm, preferably 600 to 900 nm.

When the average particle diameter of the silicon-containing particles exceeds 1,000 nm, high battery capacity may be obtained, but battery life may be very short, and when the average particle diameter of the silicon-containing particles is less than 50 nm, battery capacity and efficiency are lowered Manufacturing costs may be high.

In one embodiment, the lithium-containing oxide particle may be represented by Formula 3 below.

[Formula 3]

Li _x Ti _y O _z

In Formula 3,

x, y and z are 0.1≤x≤4, 1≤y≤5 and 2≤z≤12.

In particular, the lithium-containing oxide particles are Li ₂ TiO _3, Li ₄ Ti ₅ O ₁₂ and It may be at least one selected from the group consisting of Li ₂ Ti ₃ O ₇ , but is not limited thereto.

The average particle diameter (D50) of the lithium-containing oxide particles may be 10 to 500 nm, preferably 20 to 30 nm.

When the average particle diameter of the lithium-containing oxide particles exceeds 500 nm, battery capacity decreases, and when the average particle diameter of the lithium-containing oxide particles is less than 10 nm, high battery capacity can be obtained, but battery output may decrease.

In particular, the average particle diameter of the silicon-containing particles may be 2 to 100 times the average particle diameter of the lithium-containing oxide particles, preferably 5 to 20 times.

When the average particle diameter of the silicon-containing particles exceeds 100 times that of the lithium-containing oxide particles, the battery capacity decreases, and the average particle diameter of the silicon-containing particles is less than twice that of the lithium-containing oxide particles. High battery capacity can be obtained, but battery output may be reduced.

In one embodiment, the lithium-containing oxide particles may be included in an amount of 1 to 10% by weight, preferably 2 to 5% by weight, based on the total weight of the silicon-containing particles.

That is, the ratio of the weight of the silicon-containing particles to the weight of the lithium-containing oxide particles may be 100: 1 to 10.

When the content of the lithium-containing oxide particles exceeds 10% by weight relative to the total weight of the silicon-containing particles, the battery capacity is lowered, and the content of the lithium-containing oxide particles is less than 1% by weight relative to the total weight of the silicon-containing particles , high battery capacity can be obtained, but battery output may be reduced.

In one embodiment, the ratio of the peak heights of the lithium-containing oxide and the silicon-containing particle (peak height of the lithium-containing oxide/peak height of the silicon-containing particle) through XRD analysis of the negative electrode active material may be 0.01 to 0.5. And, preferably, it may be 0.04 to 0.14.

For example, the ratio of the heights of the lithium titanium oxide (111) peak and the silicon (111) peak may be 0.01 to 0.5, preferably 0.04 to 0.14.

In one embodiment, the core may further include amorphous carbon, and the shell may include crystalline carbon.

In particular, the shell may be mostly composed of crystalline carbon, and the additional carbon component of the core may be mostly amorphous carbon.

In addition, the shell may include a small amount of amorphous carbon, and the core may include a small amount of crystalline carbon.

When a small amount of crystalline carbon is included in the core, the specific gravity of graphite may increase as the distance from the center of the core increases.

In one embodiment, the content ratio (crystalline content / amorphous carbon content) of crystalline carbon and amorphous carbon through Raman analysis of the negative electrode active material may be 0.1 to 5.

That is, the height ratio (I _d /I _g ) of the amorphous carbon corresponding peak (I _d ) and crystalline carbon corresponding peak (I _g ) through Raman analysis of the negative electrode active material may be 0.1 to 5, preferably 1.05 to 5 It may be 1.1.

The amorphous carbon of the core may surround silicon-containing particles coated with lithium-containing oxide particles while positioned between the silicon-containing particles coated with lithium-containing oxide particles. That is, the amorphous carbon may serve as a matrix, and the silicon-containing particles coated on the surface of the lithium-containing oxide particles may become a core in which silicon-containing particles are dispersed.

The added carbon component of the shell and core may play a role of mitigating the volume expansion of silicon-containing particles coated with lithium-containing oxide particles on their surfaces during charging and discharging.

Meanwhile, pores may be formed in the core of the anode active material, and internal pores of the core may reduce initial irreversible capacity of the battery and help mitigate volume expansion of Si.

The volume of the pores formed in the core may be 0.01 to 0.25 cc/g. As the distance from the center of the core increases, the specific gravity of the void may decrease.

A method for producing an anode active material according to another aspect of the present application is a silicon-containing particle. A step of mixing and compounding a lithium precursor, a metal precursor, amorphous carbon and crystalline carbon and a heat treatment step may be included.

The metal may be at least one selected from Si, Al, Ti, Mn, Ni, Cu, V, Zr, Mn, Co, Fe, and Nb.

In the complexing step, the proportions of the lithium precursor and the metal precursor may be mixed according to the stoichiometric ratio of lithium to metal of the lithium-containing oxide to be formed.

In the conjugation step, an anode active material having a core-shell structure is formed. During the conjugation step, a shell layer is formed and a lithium precursor and a metal precursor are positioned on the silicon-containing particle.

Thereafter, through the heat treatment step, while the lithium precursor and the metal precursor located on the silicon-containing particle react to form lithium-containing oxide particles, the silicon-containing particles are coated with the lithium-containing oxide particles.

That is, the manufacturing method of the negative electrode active material of the present disclosure does not require separate steps of preparing lithium-containing oxide particles and coating the lithium-containing oxide particles, and silicon-containing particles are coated with lithium-containing oxide particles through a complexing step and a heat treatment step.

In one embodiment, the lithium precursor is Li ₂ CO _3, LiOH, LiOH (monohydrate, monohydrate), lithium acetate (Li acetate), lithium isopropoxide (Li isopropoxide), LiCl and It may be at least one selected from the group consisting of Li ₂ O, and the metal precursor is titanium isopropoxide, titanium tetrachloride (IV), titanium tetrachloride (III) ( Ti tetrachloride (III), titanium chloride (Ti chloride), titanium acetate (Ti acetate) and TiO ₂ It may be any one or more selected from the group consisting of.

In addition, the amorphous carbon is coal-based pitch, mesophase pitch, petroleum-based pitch, tar, coal-based oil, petroleum-based heavy oil, organic synthetic pitch, sucrose, naphthalene resin, polyvinyl alcohol resin, furfuryl alcohol (furfuryl alcohol) resin, polyacrylonitrile resin, polyamide resin, phenol resin, furan resin, cellulose resin, styrene resin, epoxy resin or vinyl chloride resin, block copolymers, polyols and polyimide resins selected from the group consisting of Any one or more, and the crystalline carbon may be any one or more selected from the group consisting of natural graphite, artificial graphite, expanded graphite, graphene, carbon black, and fullerene.

Natural graphite is naturally occurring graphite, and includes flake graphite, high crystalline graphite, and microcrystalline or cryptocrystalline (amorphous) graphite. Artificial graphite is artificially synthesized graphite, which is made by heating amorphous carbon to a high temperature, and includes primary or electrographite, secondary graphite, graphite fiber, and the like.

Expanded graphite Inflates vertical layers of molecular structure by intercalating chemicals such as acids or alkalis between graphite layers and heating them. Graphene includes a single layer or multiple monolayers of graphite.

Carbon black is a crystalline material with a smaller regularity than graphite, and when carbon black is heated at about 3,000° C. for a long time, it can be changed into graphite. Fullerene is a carbon mixture containing at least 3% by weight of fullerene, which is a polyhedral bundle-shaped compound of 60 or more carbon atoms. As the first carbon-based material, one kind or a combination of two or more kinds of these crystalline carbons may be used. For example, natural graphite or artificial graphite may be used. The crystalline carbon may have a spherical, plate-like, fibrous, tubular or powdery form.

Preferably, pitch may be used as the amorphous carbon. The pitch may use a pitch having a softening point of 100 to 250 ° C, and in particular, a petroleum or coal-based pitch having a QI (quinolone insoluble) component of 5% by weight or less, more preferably 1% by weight or less may be used.

Meanwhile, as the crystalline carbon, natural graphite may be preferably used. As for the purity of the graphite, a high purity grade having a fixed carbon content of 99% by weight or more, more preferably 99.95% by weight or more can be used.

In addition, flaky graphite may be suitable for enhancing conductivity through contact with silicon.

In one embodiment, the conjugation step may be performed by a physical method.

The physical method may include at least one selected from the group consisting of milling, stirring, mixing, and compression.

For example, the compounding step may be performed by ball milling. In particular, the planetary ball mill can efficiently mix and pulverize the mixture in a non-contact manner with the composition in a rotating and revolving mixing manner.

A ball that can be used for ball milling may be, for example, a zirconia ball, and the type of ball is not limited, and the size of the ball may be, for example, about 0.3 to 10 mm, but is not limited thereto.

On the other hand, the reaction time of the complexation step is 1 minute to 24 hours, the reaction temperature is 40 ~ 250 ℃, the reaction atmosphere can be carried out under the conditions of the atmosphere or inert atmosphere.

In addition, the treatment temperature of the heat treatment step may be 700 ~ 1,100 ℃.

The heat treatment time is not particularly limited, but may be performed in the range of 10 minutes to 5 hours, for example.

An electrode according to another aspect of the present disclosure may include the negative active material, and a lithium secondary battery may include an electrode including the negative active material as a negative electrode and a positive electrode positioned opposite the negative electrode; and an electrolyte disposed between the negative electrode and the positive electrode.

The negative electrode includes the negative electrode active material. For example, after preparing a negative active material composition by mixing the negative electrode active material, a binder, and optionally a conductive agent in a solvent, the negative electrode active material composition is molded into a predetermined shape, or copper foil, etc. It can be manufactured by a method of applying to the current collector of.

The anode may further include an anode active material commonly used as an anode active material of a lithium battery in the art in addition to the anode active material described above. Commonly used anode active materials may include, for example, at least one selected from the group consisting of lithium metal, metals alloyable with lithium, transition metal oxides, non-transition metal oxides, and carbon-based materials.

For example, the metal alloyable with lithium is Si, Sn, Al, Ge, Pb, Bi, Sb Si—Y alloy (where Y is an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a transition metal, A rare earth element or a combination thereof, but not Si), a Sn-Y alloy (wherein Y is an alkali metal, an alkaline earth metal, a Group 13 to Group 16 element, a transition metal, a rare earth element, or a combination thereof, and Sn is not), etc. The element Y is Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, It may be Se, Te, Po, or a combination thereof.

For example, the transition metal oxide may be lithium titanium oxide, vanadium oxide, or lithium vanadium oxide.

For example, the non-transition metal oxide may be SnO ₂ , SiOx (0<x≤2), and the like. The carbon-based material may be crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon may be graphite such as amorphous, plate, flake, spherical or fibrous natural graphite or artificial graphite, and the amorphous carbon may be soft carbon (low-temperature calcined carbon) or hard carbon carbon), mesophase pitch carbide, calcined coke, and the like.

When the anode active material and the carbon-based material are used together, the oxidation reaction of the silicon-based active material is suppressed, an SEI film is effectively formed to form a stable film, and electrical conductivity is improved, thereby further improving the charge and discharge characteristics of lithium. there is.

Conventional anode active materials may be mixed and blended with the anode active material described above, coated on the surface of the anode active material, or used in any other combination.

The binder used in the negative electrode active material composition is a component that assists in the bonding of the negative electrode active material and the conductive agent and the bonding to the current collector, and is added in an amount of 1 to 50 parts by weight based on 100 parts by weight of the negative electrode active material. For example, the binder may be added in an amount of 1 to 30 parts by weight, 1 to 20 parts by weight, or 1 to 15 parts by weight based on 100 parts by weight of the negative electrode active material.

Examples of such binders include polyvinylidene fluoride, polyvinylidene chloride, polybenzimidazole, polyimide, polyvinyl acetate, polyacrylonitrile, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropyl Cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polyaniline, acrylonitrile butadiene styrene, phenol resin, epoxy resin, polyethylene terephthalate, polytetrafluoro Roethylene, polyphenylsulfide, polyamideimide, polyetherimide, polyethylenesulfone, polyamide, polyacetal, polyphenylene oxide, polybutyleneterephthalate, ethylene-propylene-dienter polymer (EPDM), sulfonated EPDM , styrene butadiene rubber, fluororubber, various copolymers, and the like.

The negative electrode may optionally further include a conductive agent in order to further improve electrical conductivity by providing a conductive passage to the negative electrode active material.

As the conductive agent, anything generally used in a lithium battery may be used, and examples thereof include carbon-based materials such as carbon black, acetylene black, ketjen black, and carbon fiber (eg vapor grown carbon fiber); metal-based materials such as metal powders or metal fibers, such as copper, nickel, aluminum, and silver; A conductive material comprising a conductive polymer such as a polyphenylene derivative or a mixture thereof can be used. The content of the conductive material can be appropriately adjusted and used. For example, the weight ratio of the negative electrode active material and the conductive agent may be added in a range of 99:1 to 90:10.

N-methylpyrrolidone (NMP), acetone, water, etc. may be used as the solvent. The amount of the solvent is 1 to 10 parts by weight based on 100 parts by weight of the negative electrode active material. When the content of the solvent is in the above range, the operation for forming the active material layer is easy.

In addition, the current collector is generally made to have a thickness of 3 to 500 μm. The current collector is not particularly limited as long as it does not cause chemical change in the battery and has conductivity. For example, the surface of copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel A surface treated with carbon, nickel, titanium, silver, or the like, an aluminum-cadmium alloy, or the like may be used.

In addition, fine irregularities may be formed on the surface to enhance the bonding strength of the negative electrode active material, and may be used in various forms such as films, sheets, foils, nets, porous materials, foams, and nonwoven fabrics.

A negative electrode plate may be obtained by directly coating the prepared negative active material composition on a current collector to prepare a negative electrode plate, or by casting on a separate support and laminating a negative active material film peeled from the support to a copper foil current collector. The negative electrode is not limited to the forms listed above and may have forms other than the above forms.

The negative active material composition may be used not only for manufacturing an electrode of a lithium secondary battery, but also for manufacturing a printable battery by being printed on a flexible electrode substrate.

Separately, a cathode active material composition in which a cathode active material, a conductive agent, a binder, and a solvent are mixed is prepared to manufacture a cathode.

As the cathode active material, any lithium-containing metal oxide commonly used in the art may be used.

For example, Li _a A _1-b B _b D ₂ (wherein 0.90≤a≤1.8 and 0≤b≤0.5); Li _a E _1-b B _b O _2-c D _c (wherein 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiE _2-b B _b O _4-c D _c (wherein 0≤b≤0.5 and 0≤c≤0.05); Li _a Ni _1-bc Co _b B _c D _α (wherein 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li _a Ni _1-bc Co _b B _c O _2-α F _α (wherein 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li _a Ni _1-bc Co _b B _c O _2-α F _α (wherein 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li _a Ni _1-bc Mn _b B _c D _α (wherein 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li _a Ni _1-bc Mn _b B _c O _2-α F _α (wherein 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li _a Ni _1-bc Mn _b B _c O _2-α F _α (wherein 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li _a Ni _b E _c G _d O ₂ (wherein 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1); Li _a Ni _b Co _c Mn _d GeO ₂ (wherein 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1); Li _a NiG _b O ₂ (in the above formula, 0.90≤a≤1.8, 0.001≤b≤0.1); Li _a CoG _b O ₂ (in the above formula, 0.90≤a≤1.8, 0.001≤b≤0.1); Li _a MnG _b O ₂ (in the above formula, 0.90≤a≤1.8, 0.001≤b≤0.1); Li _a Mn ₂ G _b O ₄ (wherein, 0.90≤a≤1.8, 0.001≤b≤0.1); QO ₂ ; QS ₂ ; LiQS ₂ ; V ₂ O ₅ ; LiV ₂ O ₅ ; LiIO ₂ ; LiNiVO ₄ ; Li _(3-f) J ₂ (PO ₄ ) ₃ (0≤f≤2); Li _(3-f) Fe ₂ (PO ₄ ) ₃ (0≤f≤2); A compound represented by any one of the chemical formulas of LiFePO ₄ may be used.

In the above formula, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or combinations thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or combinations thereof.

Of course, one having a coating layer on the surface of this compound may be used, or a mixture of the compound and a compound having a coating layer may be used. The coating layer may include a coating element compound of an oxide, a hydroxide, an oxyhydroxide of a coating element, an oxycarbonate of a coating element, or a hydroxycarbonate of a coating element. 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. In the process of forming the coating layer, any coating method may be used as long as the compound can be coated in a method (eg, spray coating, dipping method, etc.) that does not adversely affect the physical properties of the positive electrode active material by using these elements. Since it is a content that can be well understood by those skilled in the art, a detailed description thereof will be omitted.

For example, LiNiO ₂ , LiCoO ₂ , LiMn _x O _2x (x=1, 2), LiNi _1-x Mn _x O ₂ (0<x<1), LiNi _1-xy Co _x Mn _y O ₂ (0 ≤x≤0.5, 0≤y≤0.5), LiFeO ₂ , V ₂ O ₅ , TiS, MoS, and the like may be used.

In the cathode active material composition, the conductive agent, binder, and solvent may be the same as those of the anode active material composition described above. In some cases, it is also possible to form pores in the electrode plate by further adding a plasticizer to the positive active material composition and the negative active material composition. The content of the cathode active material, conductive agent, binder, and solvent is at a level commonly used in a lithium battery.

The cathode current collector has a thickness of 3 to 500 μm, and is not particularly limited as long as it does not cause chemical change in the battery and has high conductivity. For example, stainless steel, aluminum, nickel, titanium, fired carbon, Alternatively, aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, or the like may be used. The current collector may form fine irregularities on its surface to increase the adhesion of the positive electrode active material, and various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven fabrics are possible.

The prepared cathode active material composition may be directly coated on a cathode current collector and dried to prepare a cathode electrode plate. Alternatively, a positive electrode plate may be manufactured by casting the positive active material composition on a separate support and then laminating a film obtained by peeling from the support on a positive current collector.

The positive electrode and the negative electrode may be separated by a separator, and any separator commonly used in a lithium battery may be used. In particular, those having low resistance to ion migration of the electrolyte and excellent ability to absorb the electrolyte are suitable. For example, it is a material selected from glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), and combinations thereof, and may be in the form of non-woven fabric or woven fabric. The separator has a pore diameter of 0.01 to 10 μm and a thickness of generally 5 to 300 μm.

The lithium salt-containing non-aqueous electrolyte is composed of a non-aqueous electrolyte and lithium. A non-aqueous electrolyte, a solid electrolyte, an inorganic solid electrolyte, and the like are used as the non-aqueous electrolyte.

Examples of the nonaqueous electrolyte include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and gamma-butyl Rolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyl tetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, acetonitrile, nitromethane, methyl formate, Methyl acetate, phosphoric acid triesters, trimethoxy methane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ether, An aprotic organic solvent such as methyl propionate or ethyl propionate may be used.

Examples of the organic solid electrolyte include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphoric acid ester polymers, poly agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, A polymer containing an ionic dissociation group or the like can be used.

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

The lithium salt can be used as long as it is commonly used in lithium batteries, and is a material that is good for dissolving in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, lithium chloroborate, lower aliphatic carbolic acid One or more materials such as lithium carbonate, lithium 4 phenyl borate, imide, etc. may be used.

Lithium secondary batteries can be classified into lithium ion batteries, lithium ion polymer batteries, and lithium polymer batteries according to the type of separator and electrolyte used, and can be classified into cylindrical, prismatic, coin, pouch, etc. depending on the shape, Depending on the size, it can be divided into a bulk type and a thin film type.

Methods for manufacturing these batteries are well known in the art, so detailed descriptions are omitted.

Hereinafter, the present application will be described in more detail using Examples and Comparative Examples, but the present application is not limited thereto.

[Example 1]

35 parts by weight of silicon (Si, D ₅₀ : 807 nm), 5 parts by weight of a mixture of lithium carbonate (Li ₂ CO ₃ ) and titanium dioxide (TiO ₂ , D ₅₀ : 21 nm), 20 parts by weight of pitch-based carbon and 40 Part by weight of flaky graphite was mixed, put into a compounding machine (manufactured by Hansol Chemical), compounded for 10 minutes, and then heat treated in an argon (Ar) gas atmosphere at 900 ° C. for 3 hours to prepare an anode active material.

The proportions of lithium carbonate and titanium dioxide were mixed according to the stoichiometric coefficient of Li ₄ Ti ₅ O ₁₂ , the lithium titanium oxide to be formed. Considering the loss rate due to the volatility of lithium, the weight ratio of lithium to titanium mixed was 4.5 5.

[Example 2]

An anode active material was prepared in the same manner as in Example 1, except that silicon having an average particle diameter (D50) of 107 nm was used.

[Example 3]

An anode active material was prepared in the same manner as in Example 1, except that silicon having an average particle diameter (D50) of 1.06 μm was used.

[Example 4]

An anode active material was prepared in the same manner as in Example 1, except that titanium dioxide having an average particle diameter (D50) of 100 nm was used.

[Example 5]

An anode active material was prepared in the same manner as in Example 1, except that the mixing amount of the mixture of lithium carbonate and titanium dioxide was 10 parts by weight.

[Comparative Example 1]

An anode active material was prepared in the same manner as in Example 1, except that the mixture of lithium carbonate and titanium dioxide was not mixed.

[Comparative Example 2]

An anode active material was prepared in the same manner as in Example 1, except that L ₄ T ₅ O ₁₂ (SAT Nano Technology Material Co., Ltd.) having an average particle diameter (D50) of 100 nm was mixed instead of a mixture of lithium carbonate and titanium dioxide. did

[Comparative Example 3]

An anode active material was prepared in the same manner as in Example 1, except that silicon coated with lithium titanium oxide (Li ₂ TiO ₃ ) prepared by a solution coating method was used instead of a mixture of silicon, lithium carbonate, and titanium dioxide.

In the solution coating method, titanium alkoxide was first stirred and dispersed in ethanol for 1 hour, and then silicon powder was added to the solution and then stirred and dispersed for 2 hours. Thereafter, lithium hydroxide powder was added to the solution and dispersed by stirring for 1 hour, and the mixed solution was dried through solvothermal synthesis at a temperature of 40 degrees or more to recover the dried powder.

[Production Example]

Coin Half Cell Fabrication

An anode slurry was prepared by uniformly mixing the anode active material, conductive material (Super P), and binder (SBR-CMC) prepared in Examples 1 to 5 and Comparative Examples 1 to 3 in a weight ratio of 93:3:4.

The prepared negative electrode slurry was coated on a copper foil current collector having a thickness of 20 μm, and the coated electrode plate was dried at 120° C. for 30 minutes, and then pressed to prepare a negative electrode.

Metal lithium is used as the anode and counter electrode, a PE separator is used as the separator, and EC (ethylene carbonate): DEC (diethyl carbonate): DMC (dimethyl carbonate) (3 :5:2 volume ratio) A CR2032 type coin half cell was prepared by using 1.0M LiPF6 dissolved in a mixed solvent.

coin full cell fabrication

Using the negative electrode used in the coin half cell, the positive electrode was prepared as follows. A positive electrode slurry was prepared by mixing LiNi _0.6 Co _0.2 Mn _0.2 O ₂ as a positive electrode active material and PVA-PAA as a binder in a weight ratio of 1: 1, and the positive electrode slurry was coated on an aluminum foil current collector having a thickness of 12 μm, and the coating The completed electrode plate was dried at 120° C. for 15 minutes, and then pressed to prepare a positive electrode.

The anode and cathode are used, a PE separator is used as the separator, and the electrolyte is EC (ethylene carbonate): DEC (diethyl carbonate): DMC (dimethyl carbonate) (2: 1: 7 volume ratio) + FEC A CR2032 type coin full cell was prepared by dissolving 1.5M LiPF6 in a 20% mixed solvent.

Evaluation Example 1: XRD, Raman and BET analysis

An X-ray diffraction (XRD) experiment was performed on the anode active material prepared in Example 1, and the results are shown in FIG. 2A. XRD was measured using Cu-Kα radiation.

As shown in FIG. 2a, in addition to the peak corresponding to carbon (near 26°), the peak corresponding to silicon (111) (near 18°) and the peak corresponding to Li ₄ Ti ₅ O ₁₂ (111) (near 28°) ) was measured, and through this, it was confirmed that Li ₄ Ti ₅ O ₁₂ was formed.

In addition, the negative electrode active material prepared in Example 1 was analyzed using a LabRam HR Evolution Raman spectrometer (Horiba Jobin-Yvon, France), and the results are shown in FIG. 2B.

The Raman system used an Ar+ ion laser operating at a power of 10 mW with an excitation wavelength of 514 nm.

As shown in FIG. 2B, peaks corresponding to silicon (near 500 cm ^-1 ) and carbon D band (near 1320 cm ^-1 ) and G bands (near 1600 cm ^-1 ) can be identified, respectively. there was.

Table 1 below shows XRD and Raman measurement results of the anode active materials prepared in Examples 1 to 5 and Comparative Examples 1 to 3.

Through XRD and Raman analysis, it was confirmed that the anode active material of the present application includes silicon, lithium titanium oxide, and carbon.

In addition, the pore volume of the negative electrode active materials of Examples 1 to 5 and Comparative Examples 1 to 3 was measured using a Micromeritics TriStar II 3020 instrument, and is shown in Table 1 below.

The pore volume was measured through the amount of adsorption of nitrogen gas according to the relative pressure change at liquid nitrogen temperature (77K).

Silicon size (D ₅₀ )
(nm) LTO (Li ₄ Ti ₅ O ₁₂ ) Size (D ₅₀ )
(nm) Si: LTO (Li ₄ Ti ₅ O ₁₂ ) Fraction XRD peak ratio (LTO(Li ₄ Ti ₅ O ₁₂ ) /Si) Void volume (cc/g) I _d /I _g Example 1 807 22 95:5 0.049 0.026 1.09 Example 2 107 21 95:5 0.087 0.197 1.07 Example 3 1063 21 95:5 0.041 0.013 1.08 Example 4 798 100 95:5 0.084 0.025 1.08 Example 5 802 23 90:10 0.132 0.012 1.05 Comparative Example 1 792 - 100:0 - 0.048 1.08 Comparative Example 2 799 100 95:5 0.185 0.010 1.09 Comparative Example 3 803 ~34 95:5 - 0.011 1.08

The XRD peak ratio in the above table is the ratio of the heights of the (111) peak (~18°) of Li ₄ Ti ₅ O ₁₂ and the (111) peak (~28°) of Si.

I _d /I _g in the above table is the ratio of the peak heights of the D and G bands of carbon in Raman measurement.

Evaluation Example 2: SEM and TEM analysis

The results of scanning electron microscope (SEM) analysis on the cross section of the negative electrode active material prepared in Example 1 are shown in FIG. 3A.

A core containing silicon particles coated on the surface of Li ₄ Ti ₅ O ₁₂ particles and a carbon-based shell surrounding the core were identified.

In addition, in order to confirm the shape of the silicon particles coated on the surface of the Li ₄ Ti ₅ O ₁₂ particles, the results of transmission electron microscopy (TEM) analysis are shown in FIG. 3B.

Li ₄ Ti ₅ O ₁₂ particles coating the surface of the silicon particles were confirmed.

That is, through SEM and TEM analysis, it was confirmed that the negative electrode active material of the present application has a core-shell structure, and the surface of the silicon particles included in the core is partially coated with lithium titanium oxide particles.

Evaluation Example 3: FIB-EDS analysis

The negative electrode active material prepared in Example 1 was sampled by FIB (Nova200 manufactured by FEI), and EDS analysis was performed using STEM-EDS (JEOL-2200FS manufactured by Nippon Electronics Co., Ltd.) under conditions of an acceleration voltage of 200 kV.

By EDS mapping, images shown in Fig. 4 were obtained for each element. It was confirmed that the concentration of Si indicating the position of the silicon particle and the concentration of Ti indicating the position of the Li ₄ Ti ₅ O ₁₂ particle were high in the region corresponding to the core.

In addition, it was confirmed that the concentration of carbon was high in the region corresponding to the shell.

That is, the components of the core and the shell of the negative electrode active material of the core-shell structure of the present application could be specifically confirmed through FIB analysis.

Evaluation Example 4: Battery Characteristics Evaluation

The battery characteristics of the coin half cell and the coin full cell manufactured using the negative electrode active material prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were evaluated as follows.

A coin full cell was used to evaluate lifespan characteristics and high rate characteristics, and a coin half cell was used to evaluate other battery characteristics.

The coin half-cells manufactured using the negative electrode active materials prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to constant current until the voltage reached 0.01V (vs. Li) at a current of 0.1C rate at 25 ° C, respectively. After charging, constant voltage charging was performed until the current reached 0.05C while maintaining 0.01V. After resting the charged cell for 10 minutes, it was discharged with a constant current of 0.1C until the voltage reached 1.5V (vs. Li) during discharge (2 times, initial formation). The "C" is the discharge rate of the cell, which means a value obtained by dividing the total capacity of the cell by the total discharge time.

Constant current until the voltage reaches 4.2V (vs. Li) at a current of 0.1C rate at 25 ° C. After charging, constant voltage charging was performed until the current reached 0.05C while maintaining 4.2V. After resting the charged cell for 10 minutes, it was discharged with a constant current of 0.1 C until the voltage reached 2.7V (vs. Li) during discharge (2 times, initial formation).

Thereafter, the cell was charged with a constant current at 25 ° C. at a current of 1.0C rate until the voltage reached 4.2V (vs. Li), and was charged with a constant voltage until the current reached 0.05C while maintaining 4.2V. After resting the charged coin cell for 10 minutes, a cycle of discharging at a constant current of 1.0 C was repeated until the voltage reached 2.7V (vs. Li) during discharge (cycles 1 to 100).

5 shows a charge/discharge graph of the first cycle of a cell using the negative electrode active materials of Example 1 and Comparative Example 1.

The measured initial charge capacity, initial discharge capacity, initial efficiency, and lifespan characteristics of the cells using the negative electrode active materials prepared in Examples 1 to 5 and Comparative Examples 1 to 3 are shown in Table 2 below.

The initial charge capacity and the initial discharge capacity are the charge and discharge capacities in the first cycle.

Initial efficiency and lifetime characteristics were calculated from Equations 1 and 2, respectively.

<Equation 1>

Initial efficiency [%]=[Discharge capacity in the 1st cycle / Charge capacity in the 1st cycle]Х100

<Equation 2>

Life characteristics [%]=[Discharge capacity at the 100th cycle / Discharge capacity at the 1st cycle]Х100

initial charge capacity
(mAh/g) initial discharge capacity
(mAh/g) initial efficiency
(%) life characteristics
(%@100th) Example 1 1500.4 1352.4 90.1 79.1 Example 2 1373.8 1191.1 86.7 85.4 Example 3 1621.5 1479.6 91.2 70.6 Example 4 1398.2 1224.8 87.6 78.7 Example 5 1484.5 1345.0 90.6 82.2 Comparative Example 1 1507.1 1349.6 89.5 77.1 Comparative Example 2 1381.3 1155.5 83.7 80.8 Comparative Example 3 1641.9 1394.0 84.9 79.0

On the other hand, the coin half cell prepared using the negative electrode active material prepared in Example 1 and Comparative Example 1 was charged at room temperature (25 ° C. at 4.1 A and 0.01V, cut-off at 0.01V, and 5 to 10 mV of Impedance values according to the number of charge/discharge cycles (1, 2, and 10 times) were measured under conditions of a very small excitation amplitude and a frequency of 1 MHz to 1 mHz, and are shown in FIG. 6 .

Z _re (Ω) on the horizontal axis of FIG. 6 means real impedance, and Z _im (Ω) on the vertical axis means impedance on the imaginary part.

As a result of measuring and comparing the resistance values (diameter size of the semicircle) in the first charge/discharge cycle, it was confirmed that the resistance value of Example 1 was smaller than that of Comparative Example 1.

In addition, as the number of cycles increased, both the resistance values of Example 1 and Comparative Example 1 increased, but it was confirmed that the increase in the resistance value of Example 1 was smaller than that of Comparative Example 1.

Through this, it was confirmed that the resistance value could be lowered by the formation of Li ₄ Ti ₅ O ₁₂ particles.

In addition, the cells in which the initial formation was performed using the negative electrode active materials of Example 1 and Comparative Example 1 were charged until they reached 4.2V with a constant current of 0.1C, 0.2C, 0.3C, 0.5C, 1.0C, and 2.0C rates, and 4.2 While maintaining V, constant voltage charging was performed until the current reached 0.05C. After resting the charged cell for 10 minutes, discharge it with a constant current at rates of 0.1C, 0.2C, 0.3C, 0.5C, 1.0C, and 2.0C until the voltage reaches 2.7V to avoid changes in C rate. The change in the constant current/constant voltage charge capacity fraction was measured and shown in FIG. 7 .

Compared to the battery using the negative electrode active material of Comparative Example 1, it can be seen that the constant current discharge capacity fraction among the capacity developed as the current density (c-rate) increases during charging and discharging of the battery using the negative electrode active material of Example 1 is larger. there was.

That is, it was confirmed that the output characteristics of the battery using the negative active material of Example 1 were superior to those of the battery using the negative active material of Comparative Example 1.

Table 3 shows the measured output characteristics and internal resistance characteristics of the cells using the negative electrode active materials prepared in Examples 1 to 5 and Comparative Examples 1 to 3.

The output characteristics were calculated from Equation 3 below.

<Equation 3>

Output characteristics [%] = [discharge capacity of when discharged at a rate of 2.0C/discharge capacity when heat is generated at a rate of 0.1C] Х100

output characteristics
(%@2.0 C) AC Resistance (Ω) Example 1 79.1 58.6 Example 2 77.2 66.1 Example 3 75.9 63.1 Example 4 77.8 61.2 Example 5 76.2 62.9 Comparative Example 1 75.0 64.4 Comparative Example 2 73.8 69.0 Comparative Example 3 72.5 68.7

As shown in Table 3, the cells using the negative electrode active material prepared in Examples 1 to 5 showed excellent characteristics, especially in output characteristics and internal resistance, compared to the cells using the negative electrode active material prepared in Comparative Examples 1 to 3. was

That is, the cells using the anode active materials prepared in Examples 1 to 5 exhibited higher output characteristics and lower internal resistance characteristics than the cells using the anode active materials prepared in Comparative Examples 1 to 3.

The scope of the present invention is indicated by the claims to be described later rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts thereof are interpreted as being included in the scope of the present invention. It should be.

Claims (18)

a core comprising silicon-containing particles whose surface is entirely or partially coated with lithium-containing oxide particles; and
Including; a shell surrounding the core,
The lithium-containing oxide is represented by Formula 1 below,
cathode active material.

[Formula 1]
Li _x M _y O _z
In Formula 1,
M is at least one selected from Si, Al, Ti, Mn, Ni, Cu, V, Zr, Mn, Co, Fe, and Nb;
x>0, y>0 and 0<z≤(x+m·y)/2, where m is the oxidation number of M. According to claim 1,
The silicon-containing particles are silicon particles, silicon oxide particles, silicon carbide particles, silicon alloy particles, or a combination thereof,
cathode active material. According to claim 1,
The average particle diameter (D50) of the silicon-containing particles is 50 to 1,000 nm,
Represented by Formula 2 below,
cathode active material.

[Formula 2]
SiO _x (0≤x≤0.5) According to claim 1,
The negative electrode active material, characterized in that the lithium-containing oxide is represented by the following formula (3).

[Formula 3]
Li _x Ti _y O _z

In Formula 3,
x, y and z are 0.1≤x≤4, 1≤y≤5 and 2≤z≤12. According to claim 1,
The lithium-containing oxides are Li ₂ TiO _3, Li ₄ Ti ₅ O ₁₂ and At least one selected from the group consisting of Li ₂ Ti ₃ O ₇
cathode active material. According to claim 1,
The average particle diameter (D50) of the lithium-containing oxide particles is 10 to 500 nm,
cathode active material. According to claim 1,
The average particle diameter of the silicon-containing particles is 2 to 100 times the average particle diameter of the lithium-containing oxide particles,
cathode active material. According to claim 1,
The ratio of the weight of the silicon-containing particles to the weight of the lithium-containing oxide particles is 100: 1 to 10,
cathode active material. According to claim 1,
The ratio of the height of the peak of the lithium-containing oxide and the peak of the silicon-containing particle through XRD analysis (peak height of the lithium-containing oxide / height of the silicon-containing particle peak) is 0.01 to 0.5,
cathode active material. According to claim 1,
The height ratio (I _d /I _g ) of the amorphous carbon corresponding peak (I _d ) and crystalline carbon corresponding peak (I _g ) of the carbon through Raman analysis is 0.1 to 5,
cathode active material. According to claim 1,
The core includes amorphous carbon,
The shell comprises crystalline carbon,
cathode active material. silicon-containing particles. Mixing and complexing a lithium precursor, a metal precursor, amorphous carbon and crystalline carbon; and
Including; heat treatment step;
The metal is at least one selected from Si, Al, Ti, Mn, Ni, Cu, V, Zr, Mn, Co, Fe and Nb,
A method for producing an anode active material. According to claim 12,
The lithium precursor is Li ₂ CO _{3 ,} LiOH, LiOH (monohydrate), lithium acetate (Li acetate), lithium isopropoxide (Li isopropoxide), LiCl and At least one selected from the group consisting of Li ₂ O,
The metal precursor is titanium isopropoxide, titanium tetrachloride (IV), titanium tetrachloride (III) (Ti tetrachloride (III), titanium chloride (Ti chloride), titanium acetate (Ti acetate) and TiO ₂ At least one selected from the group consisting of,
A method for producing an anode active material. According to claim 12,
The amorphous carbon is coal-based pitch, mesophase pitch, petroleum-based pitch, tar, coal-based oil, petroleum-based heavy oil, organic synthetic pitch, sucrose, naphthalene resin, polyvinyl alcohol resin, furfuryl alcohol alcohol) resin, polyacrylonitrile resin, polyamide resin, phenol resin, furan resin, cellulose resin, styrene resin, epoxy resin or vinyl chloride resin, block copolymer, any one selected from the group consisting of polyol and polyimide resin more than
The crystalline carbon is at least one selected from the group consisting of natural graphite, artificial graphite, expanded graphite, graphene, carbon black and fullerene,
A method for producing an anode active material. According to claim 12,
The compounding step is performed by any one or more selected from the group consisting of milling, stirring, mixing, and compression.
A method for producing an anode active material. According to claim 12,
The treatment temperature of the heat treatment step is 700 ~ 1,100 ℃,
A method for producing an anode active material. Comprising the negative electrode active material of any one of claims 1 to 11,
electrode. A negative electrode comprising the negative electrode active material of any one of claims 1 to 11;
an anode positioned opposite to the cathode; and
Including, an electrolyte disposed between the cathode and the anode;
lithium secondary battery.

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