CN111952548A - Negative electrode active material for lithium secondary battery and method for preparing same - Google Patents

Negative electrode active material for lithium secondary battery and method for preparing same Download PDF

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CN111952548A
CN111952548A CN201910408710.0A CN201910408710A CN111952548A CN 111952548 A CN111952548 A CN 111952548A CN 201910408710 A CN201910408710 A CN 201910408710A CN 111952548 A CN111952548 A CN 111952548A
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carbon
active material
negative electrode
secondary battery
electrode active
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辛昌熙
钱锡源
金焕振
尹根永
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The present invention relates to an active material used as a negative electrode material for a secondary battery, particularly, a lithium secondary battery, and a method for preparing the same.

Description

Negative electrode active material for lithium secondary battery and method for preparing same
Technical Field
The present invention relates to an active material used as a negative electrode material for a secondary battery, particularly, a lithium secondary battery, and a method for preparing the same.
Background
Recently, IT technology is rapidly developing, and thus various portable information communication devices are spreading to develop a ubiquitous society. In addition, due to environmental problems such as exhaustion of fossil fuels and global warming, interest in electric vehicles is increasing, and efficient energy management is required in the development of new renewable energy. In order to meet the age change as described above, research and development of batteries (batteries) that can effectively store energy has been conducted.
In lithium secondary batteries, it is known that lithium secondary batteries have excellent characteristics that not only have high operating voltage and energy density, but also can be used for a long time as compared with other secondary batteries, and that the lithium secondary batteries can satisfy complicated requirements in accordance with diversification and combination of devices. Therefore, efforts are being made to further develop the lithium secondary battery technology and enlarge the application fields thereof on a global scale.
The lithium secondary battery is also called a Rocking Chair System (Rocking Chair System) by utilizing repeated insertion (insertion) and extraction (extraction) reactions of Li ions. As a currently popular positive electrode active material, LiCoO is used2、Ni0.33Co0.33Mn0.33O2、LiMn2O4And the like, and graphite-based materials are often used as the negative electrode active material.
The graphite-based material used as the negative electrode active material may be classified into soft carbon (soft carbon) which is easily uniaxially oriented under low temperature conditions and hard carbon (hard carbon) which is difficult to be uniaxially oriented under high temperature conditions. Graphite (graphite) which is a material that is currently in widespread use is soft carbon, and has excellent charge-discharge cycle characteristics, and lithium is close to an equilibrium potential among potentials at which lithium ions are inserted into graphite, and therefore, there is an advantage that there is no difference in output voltage compared to the case where lithium metal is used. However, the graphite-based material has a small capacity (theoretical capacity: about 372mAh/g, about 830mAh/ml, reversible capacity: about 330mAh/g) and causes a problem of stability at high-speed charging. Moreover, due to the uneven solid carbide interface (SEI) generated after the initial cycle, the phenomenon of lithium ion diffusion into graphite in the electrolyte is hindered, so that considerable irreversible capacity loss is generated, and the collapse of the electrode and the cycle instability are caused.
In place of the graphite-based material, Al, Ge, Si, Sn, and the like are metal elements capable of charging and discharging lithium ions, and the capacity thereof is very large compared to conventional graphite-based materials. Among them, silicon (Si) is particularly attracting attention because it exhibits the most excellent characteristics in terms of capacity by weight and volume and the lowest discharge voltage.
However, when the weight and volume after the reaction with lithium are taken into consideration, the change of the graphite-based material is small, and conversely, in the case of including SiAmong the metal elements, a large change in structure occurs due to reaction with Li, and a large volume expansion can occur. In graphite, when lithium is inserted into graphite, the structure of graphite is maintained by having lithium in the internal space of graphite, but since a metal element such as Si undergoes an alloying (alloying) reaction with Li, a large change in structure occurs, and volume expansion occurs. The volume expansion is 100 to 400% depending on the metal, and about 400% in the case of silicon. In particular, unlike metals, Li alloys are Zintl phase (Li) that exhibit ion binding propertiesx+Mx-) Therefore, in general, mechanical stability will be reduced due to mechanical stress (stress) which is fragile and varies according to volume. Therefore, when a metal element capable of forming a Li alloy is used, there is caused a problem that cracks (cracks) are generated in an electrode, and the crack is broken off to lower electrical contact between particles, thereby remarkably reducing charge and discharge characteristics and capacity of a secondary battery.
The conventional proposals for solving the above problems include a method of extremely reducing the particle size of the active material (particle), a method of adding a third element which hardly reacts with lithium to the metal element, and the like. Based on this idea, various materials such as an intermetallic compound (Si — M metal), a Si nanowire (nanowire), and a Si/C composite (composite) have been proposed, but materials that are nearly popular have not been developed so far.
Disclosure of Invention
In one embodiment of the present invention, an anode active material having a high capacity and a long life as an anode active material of a lithium secondary battery is provided, and a method for simply and easily preparing the anode active material is provided.
The object of the present invention is not limited to the above. The additional object of the present invention is described throughout the specification, and can be easily understood by those skilled in the art to which the present invention pertains from the content described in the specification of the present invention.
The invention provides a method for preparing a negative electrode active material for a lithium secondary batteryThe preparation method comprises the following steps: a step of mixing a silane-based liquid material and a diol with a material having an OH group to prepare a silicon oxide intermediate material containing carbon therein; preparing a silicon oxide (SiO) containing carbon therein by heat-treating the above silicon oxide intermediate containing carbon thereinx) A step (2); and mixing the above silicon oxide powder containing carbon therein with a carbon material to prepare silicon oxide-carbon (SiO)x-C) a step of complexing.
Also, the present invention provides a negative electrode active material for a lithium secondary battery, comprising: a core composed of silicon oxide (SiO) containing carbon thereinx，0.7<x<1.4) forming; and a carbon coating layer formed of carbon particles surrounding the surface of the core portion, wherein the carbon coating layer contains carbon in an amount of 3 to 10 wt% in the silicon oxide.
The negative electrode active material for a lithium secondary battery provided in the present invention can greatly improve energy storage capacity and suppress volume expansion during use, thereby improving the life of the battery. Also, the present invention can provide a means for simply and efficiently preparing the negative electrode active material having the above-described characteristics.
Drawings
Fig. 1 is a result of X-ray diffraction (XRD) analysis of a part of examples of the present invention.
Fig. 2 is a Scanning Electron Microscope (SEM) photograph of a portion of an example of the invention.
Detailed Description
The present invention will be described in detail below. First, the negative electrode active material for a lithium secondary battery of the present invention is a silicon oxide-carbon-metal (SiO) materialxThe preparation of the-C-M) complexes is described in detail.
First, a silane-based liquid material is prepared, and, for example, Silicon tetrachloride (SiCl) is used4) Dialkyldichlorosilane (RRSiCl)2) Dichlorodimethylsilane (dichlorodimethylsilane), polydimethylsiloxane (polydimethysiloxan), oligosiloxanes (oligosiloxanes), and the like.
Preferably, the purity of the silane-based liquid substance is 85% or more. Examples of the Diol to be prepared in addition to the silane-based liquid substance include 1,2-Dihydroxyethane (1,2-Dihydroxyethane), 1,2-Ethanediol (1,2-Ethanediol), vinyl Alcohol (Ethylene Alcohol), dihydric Alcohol (glycol), Monoethylene glycol (Monoethylene glycol), Ethane-1,2-Diol (Ethane-1,2-Diol), 2-Hydroxyethanol (2-hydroxyethaneanol), and Ethylene Dihydrate (Ethylene Dihydrate).
A silicon oxide intermediate material containing carbon therein is prepared by mixing a silane-based liquid material and a diol with a material having an OH group. As the substance having OH group, water (H) can be used2O), ethanol (C) can be used as a colorless combustible compound2H5OH) or methanol (CH)3OH), isopropyl alcohol, and the like.
As a preferred example of the mixing process, first, a diol is impregnated into a functional group, and then a silane-based liquid substance is stirred to gradually react, and in this case, a substance having an OH group is supplied together to prepare the silicon oxide intermediate substance containing carbon therein. The reason why the substance having an OH group is added is that the particle size of the intermediate substance to be produced is reduced, and the carbon content contained in the intermediate substance can be optimized by having an — OH group.
On the other hand, when the above reaction is carried out, the reaction rate may be adjusted within the chemical weight ratio, and preferably, the reaction time is adjusted in consideration of the mixing time and the weight ratio of the real-time mixing. On the other hand, it is preferable that pure hydrogen chloride gas (HCl) is generated by the reaction of chlorine in the silane-based substance with the glycol, HCl generated at this time is discharged through a polyvinyl chloride (PVC) pipe or a ceramic-coated pipe, and the discharged HCl gas is removed by a scrubber.
On the other hand, the silane-based liquid material, the diol and the substance having an OH group are preferably mixed in the following amounts by weight: 40-60%, diol: 20-50%, substance having an OH group: 10 to 50 percent.
If the content of the silane-based liquid substance is less than 40%, the use thereofSince Si is insufficient for forming silicon oxide, SiO cannot be performedxIn combination, at greater than 60%, SiO cannot be prepared due to the rapid oxidation reaction caused by excess silanex。
If the diol content is less than 20%, oxygen bonded to Si is insufficient, and therefore SiO cannot be bonded theretoxWhen the amount is more than 50%, SiO is generated due to excessive oxygen2The binding can thereby result in a reduction in capacity, and therefore, preferably, does not exceed 50%.
On the other hand, the substance having an OH group is added to reduce the particle size by decomposing O — Si — O bonds by adding an OH group (group), and when less than 10%, it is difficult to expect the effect as a terminator (terminator) due to the decrease in the content, and when more than 50%, excessive decomposition due to excessive addition suppresses SiOxTherefore, preferably, it does not exceed 50%. More preferably, 30% or less.
The obtained silicon oxide intermediate substance containing carbon therein is subjected to a heat treatment to form a silicon oxide containing carbon therein. Preferably, the silicon oxide at this time has an oxygen content (x) of 0.7< x <1.4, and preferably, the content of carbon contained inside is 3 to 10 weight percent. The carbon contained in the interior is located in a cluster form in the interior of the silicon oxide. That is, carbon contained in the interior is formed in a carbon cluster state.
Preferably, the heat treatment is performed at a temperature ranging from 400 to 1200 ℃ for 30 minutes to 12 hours. The above-mentioned intermediate matters may be heat-treated in a heat treatment furnace including a vertical, horizontal or conveyor belt. When the heat treatment is performed, hydrogen chloride (HCl) gas remaining from the hydrogenation reaction between chlorine in the silane-based substance and the diol is evaporated, silicon oxide having an oxygen number of less than 1.4 is formed by the reaction between silicon clusters in the silane-based substance and oxygen in the diol, and carbon remaining in the diol reacts with the silicon oxide, thereby preparing silicon oxide containing carbon.
When the heat treatment temperature is less than 400 ℃, the residual hydrogen chloride gas is not evaporated, and the capacity of the silicon oxide as the anode material is reduced, and when the temperature is more than 1200 ℃, the particles of the prepared silicon oxide grow roughly to be larger than 10 μm or more, and this may cause the capacity of the anode material to be reduced. When the heat treatment time is less than 30 minutes, the evaporation of hydrogen chloride gas is reduced as in the case of a low temperature, and when the time is more than 12 hours, a problem of particle growth may occur.
In order to make the particle size of the silicon oxide containing carbon uniform, the particle size is prepared to be 1 to 50 μm, preferably 2 to 10 μm, by using a milling machine including a grinder (attritor), a planer (planer), spex, a ball mill (ball mill), a mixer (mixer), and the like. If the particle size is too small, tap density (tap density) is increased when preparing the electrode, thereby having a disadvantage of requiring a large amount of electrode powder, and if the particle size is too large, then there is a disadvantage of too low tap density.
For example, when a ball mill is used, the rotation speed is preferably 200 to 500rpm for 30 minutes to 12 hours. If the rotation speed is too slow, the crushing and the pressure bonding are insufficient, and the particle size cannot be controlled to 50 μm or less, and if the rotation speed is too fast, the particles may be reduced to a nanometer size by an excessive energy source. On the other hand, if the ball milling time is less than 30 minutes, the particle size cannot be reduced, and if it exceeds 12 hours, the particles may be reduced to a nano size due to excessive energy.
The silicon oxide containing carbon inside is mixed with a carbon material to prepare a silicon oxide-carbon composite. Preferably, the Carbon material is a Carbon-based material such as artificial graphite, natural graphite, graphene (graphene), Carbon Nanotube (CNT), or the like. The silicon oxide containing carbon therein and the carbon material may be mixed by the milling method, and a ball mill using balls (having a diameter of 1 to 100mm) made of zirconia, alumina, ceramics, or the like may be preferably used as the mixing method. In this case, the mixing ratio of the silicon oxide containing carbon to the carbon material is preferably 3:97 to 50: 50. When the mixing ratio of the silicon oxide and the carbon material is less than 3:97, the capacity of the silicon oxide is not reflected, and it is difficult to expect an increase in the capacity as the negative electrode material, and when it exceeds 50:50, the volume of the silicon oxide rapidly expands, and the capacity of the negative electrode material rapidly decreases.
When the ball milling is performed, the ball milling is preferably performed at a rotation speed of 100 to 500rpm for 20 minutes to 20 hours. If the ball milling rotation speed is less than 100rpm or the time is less than 20 minutes, physical crushing, pressure bonding, and rotational energy are not reflected, and mixing is not possible. It is thought that if the rotation speed is more than 500rpm or the time is more than 20 hours, the particle sites are rapidly nanocrystallized to decrease the capacity by increasing the tap density.
On the other hand, a silicon oxide-carbon-metal (SiO) can be prepared by mixing the above silicon oxide-carbon composite and a metal as necessaryx-C-M, wherein M is a metal). The initial irreversible (initial columnar carbon) of the prepared silicon oxide-carbon composite is about 70-78%, and 22-30% of initial capacity reduction cannot be avoided. Therefore, SiO is suppressed by adding a metal having a bonding speed with oxygen higher than that of Si-OxSo that a metal may be added in order to suppress the non-reversibility.
The metal may be a transition metal such as aluminum (Al), cobalt (Co), or zirconium (Zr). The above SiOx-C composite and metal are mixed in a ratio of 1:99 to 30:70, in which case it is preferably carried out by means of ball milling. If the mixing ratio of the silicon oxide-carbon composite and the metal is less than 1:99, the metal element is too low, and it is difficult to expect the effect of suppressing oxidation, and if it exceeds 30:70, the capacity may be decreased due to precipitation of the metal element.
Preferably, the ball milling is performed at a rotation speed of 100 to 500rpm for 30 minutes to 12 hours. When the ball milling is performed at a rotation speed of less than 100rpm or for a time of less than 30 minutes, sufficient energy is not reflected, and thus, it is difficult to form a complex with the metal. On the contrary, when the rotation speed is more than 500rpm and the rotation is performed for more than 12 hours, SiO which is a metal elementxLattice distortion phenomenon caused by addition occurs in the crystal structure, thereby reducing the capacity.
Hereinafter, the negative electrode active material for a lithium secondary battery of the present invention will be described in detail. Preferably, the anode active material of the present invention is a silicon oxide-carbon composite, that is, including: a core portion of silicon oxide containing carbon in the form of carbon clusters therein; and a carbon coating layer formed of carbon particles surrounding the core portion. For example, the complex may be in the form of a core shell.
Preferably, the carbon clusters account for 3 to 10 weight percent of the entire silicon oxide. SiO which is substantially inhibited from generating carbon in silicon oxide existing in the form of the above-mentioned carbon clusterxThereby serving to inhibit the initial non-reversible effect. The carbon present in the interior packed with clusters serves as a barrier for particle growth, i.e., volume expansion, and serves to suppress volume expansion to reduce non-reversibility.
Preferably, the particle size of the negative electrode active material of the present invention is 3 to 20 μm, the particle size of the core portion in the negative electrode active material is 1 to 3 μm, preferably 1.5 to 2.5 μm, and the thickness of the carbon coating layer is 0.5 to 1 μm.
On the other hand, the negative electrode active material of the present invention may be silicon oxide-carbon-metal (SiO) further including a metal layer outside the carbon coating layerx-C-M, wherein M is a metal). In the case where the above-mentioned outer portion further includes a metal layer, SiOxThe initial non-reversible (initial) capacity of-C is about 70-78%, and 22-30% of initial capacity reduction is unavoidable, so that SiO is inhibited by adding a metal having a faster binding rate to oxygen than Si-OxThereby obtaining the technical effect of increasing the non-reversibility.
The metal layer may be made of aluminum (Al), cobalt (Co), zirconium (Zr), etc., and preferably has a thickness of 0.5 to 1 μm.
Hereinafter, examples of the present invention will be described in detail. The following examples are only to help understanding of the present invention, and the scope of the present invention is not limited to the examples.
Examples
Silicon oxide intermediate substances containing carbon therein were prepared by mixing starting materials having the composition ranges (weight percentages) of table 1 below, and silicon oxide containing carbon therein was prepared by subjecting the silicon oxide intermediate substances to a heat treatment at a temperature of 400 ℃ for 2 hours, after which carbon materials were mixed to prepare a silicon oxide-carbon composite. In this case, the carbon material was mixed by ball milling (500rpm, 4 hours).
TABLE 1
Example (b) Liquid silane material (silicon tetrachloride, SiCl)4) Dihydric alcohol (ethylene glycol) Other ingredients
Inventive example 1 45 45 Ethanol content is 10%
Inventive example 2 35 35 30 percent of ethanol
Inventive example 3 25 25 50 percent of ethanol
Inventive example 4 45 45 Water (H)2O)10％
Inventive example 5 35 35 Isopropanol 30%
With respect to the prepared silicon oxide-carbon composite described above, the crystal structure of the powder was confirmed by X-ray diffraction analysis, and the results thereof are shown in fig. 1. FIG. 1 is a diagram illustrating X-ray Diffraction (X-ray Diffraction) analysis of invention examples 1 to 3 in Table 1. As a result of analysis, the crystalline structure of the powder in which OH groups were added to the starting material at other ratios had the same structure as that of SiO prepared by the present inventionxAnd Shin-Etsu SiO for comparative analysisxThe same crystal structure. In the above results, the addition of OH group promotes the action of a terminator bonded to Si-O-Si, but does not affect the crystal structure.
On the other hand, fig. 2 shows the results of analyzing the silicon oxide-carbon composite powders prepared by the above inventive examples 1, 4 and 5 using a Scanning Electron Microscope (SEM). In FIG. 2, part (a) is invention example 4, part (b) is invention example 1, and part (c) is invention example 5.
As shown in FIG. 2, the powders prepared by the present invention all have a porous surface for the following reasons, namely, SiCl4With ethylene glycol and H as OH group2The evaporation of HCl gas generated when O, isopropyl alcohol (isopropanol) and ethanol are reacted generates bubbles on the powder surface and discharges the bubbles to cause a surface reaction.
The porous surface plays a role of suppressing the charge/discharge of lithium due to 2SiO2+4Li+4e-＝Li4SiO4The irreversible cause of the effect of + Si lithium silicate (lithium silicate). I.e. the porous surface acts as a barrier to Li produced while at the same time acting as a barrier4SiO4The volume expansion of + Si lithium silicate (lithium silicate) suppresses the addition by volume expansion to be irreversible, and promotes the particle size reduction in ethylene glycol reacted with 1-, 2-or 3-membered OH groups to prepare optimum SiOx-C corresponds to a powder.
On the other hand, the electrochemical characteristics of the prepared silicon oxide-carbon composite powder were evaluated and shown in table 2. On the other hand, the characteristics of the conventional pure silicon oxide (conventional example) are shown together.
To evaluate the above electrochemical properties, the ratio of 8: 1:1, the above composite powder, acetylene black and polyimide (binder) were mixed in a weight ratio, and mixed with N-methyl-2-pyrrolidone (N-methyl-2-pyrollidone) as a solvent to prepare a negative electrode slurry. At a current collector of copper foil of 5mg/cm2The above negative electrode active material was coated and dried at a temperature of 400 c for 2 hours, thereby preparing a negative electrode. On the other hand, 1.3M LiPF was used using lithium metal foil (foil) as a positive electrode6Ethyl Carbonate (EC)/diethyl carbonate (DEC) of 1:1, and a coin-type half cell (2016type) was prepared using an electrolyte solution to which 5% of Fluorinated Ethylene Carbonate (FEC) was added.
The prepared above batteries were evaluated for charge and discharge characteristics by the following conditions and the results are shown in table 2.
Voltage range (Voltage range) of 0.005-2V
Charge (Charge) CC 0.2C
Discharge (Discharge) CC 0.2C
TABLE 2
Example (b) First discharge capacity Third hundred discharge capacity First initial efficiency
Inventive example 1 1655 1112 81.3
Inventive example 2 1672 1261 82.5
Inventive example 3 1523 1108 79.8
Inventive example 4 1423 1002 80.3
Inventive example 5 1399 1011 76.5
Conventional example (SiO)x-pure) 1328 679 75.1
As shown by the above results, compared with SiO prepared by the conventional methodxThe non-reversibility of the negative electrode material of the present invention is improved.

Claims (19)

1. A method of preparing a negative active material for a lithium secondary battery, comprising:
a step of mixing a silane-based liquid material and a diol with a material having an OH group to prepare a silicon oxide intermediate material containing carbon therein;
a step of preparing a silicon oxide containing carbon inside by heat-treating the silicon oxide intermediate substance containing carbon inside; and
and a step of mixing the silicon oxide powder containing carbon therein with a carbon material to prepare a silicon oxide-carbon composite.
2. The method for producing a negative electrode active material for a lithium secondary battery according to claim 1, further comprising a step of mixing the silicon oxide-carbon composite with at least one metal selected from the group consisting of aluminum, cobalt, and zirconium to produce a silicon oxide-carbon-metal composite.
3. The method for producing a negative electrode active material for a lithium secondary battery according to claim 1, further comprising a step of homogenizing the particle size by a milling machine in order to homogenize the particle size of the silicon oxide containing carbon inside.
4. The method for producing a negative electrode active material for a lithium secondary battery according to claim 1, wherein the silane-based material is at least one of silicon tetrachloride, dialkyldichlorosilane, dichlorodimethylsilane, polydimethylsiloxane, and oligosiloxane.
5. The method for producing a negative electrode active material for a lithium secondary battery according to claim 1, wherein the diol is at least one of 1,2-dihydroxyethane, 1,2-ethanediol, vinyl alcohol, a dihydric alcohol, monoethylene glycol, ethane-1,2-diol, 2-hydroxyethanol, and ethylene dihydrate.
6. The method for preparing a negative electrode active material for a lithium secondary battery according to claim 1, wherein 40 to 60 weight percent of the silane-based material, 20 to 50 weight percent of the diol, and 10 to 50 weight percent of the material having an OH group are mixed.
7. The method for preparing a negative electrode active material for a lithium secondary battery according to claim 1, wherein the heat treatment is performed at a temperature of 400 to 1200 ℃ for 30 minutes to 12 hours to form a silicon oxide containing 3 to 10% by weight of carbon therein.
8. The method for producing a negative electrode active material for a lithium secondary battery according to claim 1, wherein the heat treatment is performed in an inert gas atmosphere containing one or more of argon, nitrogen, and hydrogen.
9. The method for producing a negative electrode active material for a lithium secondary battery according to claim 1, wherein the carbon material is obtained by mixing a silicon oxide containing carbon therein and a carbon material at a weight ratio of 3:97 to 50:50, using artificial graphite or natural graphite.
10. The method for preparing a negative electrode active material for a lithium secondary battery according to claim 1, wherein the silicon oxide-carbon composite is prepared by milling at a rotation speed of 100 to 500rpm for 20 minutes to 20 hours.
11. The method for producing a negative electrode active material for a lithium secondary battery according to claim 2, wherein the silicon oxide-carbon composite and the metal are mixed in a weight ratio of 1:99 to 30: 70.
12. The method for preparing a negative electrode active material for a lithium secondary battery according to claim 2, wherein the silicon oxide-carbon-metal composite is prepared by milling at a rotation speed of 100 to 500rpm for 30 minutes to 12 hours.
13. A negative electrode active material for a lithium secondary battery,
the method comprises the following steps:
a core composed of silicon oxide (SiO) containing carbon thereinx，0.7<x<1.4) forming; and
a carbon coating layer formed of carbon particles surrounding the surface of the core portion,
the content of carbon contained in the silicon oxide is 3 to 10 wt%.
14. The negative electrode active material for a lithium secondary battery according to claim 13, wherein carbon contained in the silicon oxide exists in the form of a carbon cluster.
15. The negative electrode active material for a lithium secondary battery according to claim 13, wherein the particle size of the negative electrode active material is 3 to 20 μm.
16. The negative electrode active material for a lithium secondary battery according to claim 13, wherein the particle size of the core portion is 1 to 3 μm.
17. The negative electrode active material for a lithium secondary battery according to claim 13, wherein the carbon coating layer has a thickness of 0.5 to 1 μm.
18. The negative electrode active material for a lithium secondary battery according to claim 13, further comprising a metal layer having a thickness of 0.5 to 1 μm formed outside the carbon coating layer.
19. The negative electrode active material for a lithium secondary battery according to claim 18, wherein the metal of the metal layer is one or more of aluminum, cobalt, and zirconium.
CN201910408710.0A 2019-05-16 2019-05-16 Negative electrode active material for lithium secondary battery and method for preparing same Pending CN111952548A (en)

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Citations (2)

* Cited by examiner, † Cited by third party
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CN105103346A (en) * 2013-12-03 2015-11-25 株式会社Lg化学 Porous silicon-based anode active material and method for preparing same, and lithium secondary battery including same
WO2019050100A1 (en) * 2017-09-05 2019-03-14 주식회사 익성 Lithium secondary battery anode active material and manufacturing method therefor

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105103346A (en) * 2013-12-03 2015-11-25 株式会社Lg化学 Porous silicon-based anode active material and method for preparing same, and lithium secondary battery including same
WO2019050100A1 (en) * 2017-09-05 2019-03-14 주식회사 익성 Lithium secondary battery anode active material and manufacturing method therefor

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