WO2017099523A1 - Method for preparing anode active material for lithium secondary battery and lithium secondary battery to which method is applied - Google Patents

Method for preparing anode active material for lithium secondary battery and lithium secondary battery to which method is applied Download PDF

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WO2017099523A1
WO2017099523A1 PCT/KR2016/014452 KR2016014452W WO2017099523A1 WO 2017099523 A1 WO2017099523 A1 WO 2017099523A1 KR 2016014452 W KR2016014452 W KR 2016014452W WO 2017099523 A1 WO2017099523 A1 WO 2017099523A1
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Prior art keywords
negative electrode
active material
electrode active
secondary battery
amorphous silicon
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PCT/KR2016/014452
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French (fr)
Korean (ko)
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조래환
이용주
김은경
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주식회사 엘지화학
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Priority claimed from KR1020160166995A external-priority patent/KR101977931B1/en
Application filed by 주식회사 엘지화학 filed Critical 주식회사 엘지화학
Priority to CN201680049763.2A priority Critical patent/CN107925067B/en
Priority to PL16873388T priority patent/PL3382779T3/en
Priority to US15/751,916 priority patent/US10511048B2/en
Priority to EP16873388.9A priority patent/EP3382779B1/en
Publication of WO2017099523A1 publication Critical patent/WO2017099523A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/021—Preparation
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/24—Deposition of silicon only
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • 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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • 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
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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

Definitions

  • the present invention relates to a method for producing a negative electrode active material for a lithium secondary battery, and a lithium secondary battery using the same.
  • Lithium secondary batteries are chargeable and dischargeable batteries that can best meet these requirements, and are currently used in portable electronic devices and communication devices such as small video cameras, mobile phones, and notebook computers.
  • a lithium secondary battery is composed of a positive electrode, a negative electrode, and an electrolyte, and lithium ions from the positive electrode active material are inserted into the negative electrode active material, that is, carbon particles, and desorbed again when discharged. Since it plays a role of transferring energy while reciprocating, charge and discharge are possible.
  • the silicon-based negative electrode active material is known as a high capacity negative electrode active material having a low price and high capacity, for example, a discharge capacity (about 4200 mAh / g) of about 10 times that of graphite, which is a commercial negative electrode active material.
  • the silicon-based negative electrode active material is a nonconductor, and due to the rapid volume change that occurs during the charging and discharging process, the accompanying side reactions, for example, pulverization of the negative electrode active material particles, or form an unstable solid electrolyte interface (SEI) layer.
  • SEI solid electrolyte interface
  • battery performance is deteriorated, such as a decrease in capacity due to electrical contact, and there is a significant limitation in commercialization.
  • the first technical problem of the present invention is to provide a method for producing a negative electrode active material for secondary batteries that can prevent oxidation during the production of nano-sized silicon particles.
  • a second object of the present invention is to provide a negative electrode active material for a secondary battery manufactured by the method for producing a negative electrode active material.
  • a third object of the present invention is to provide a negative electrode for a secondary battery including the negative electrode active material of the present invention.
  • a fourth technical object of the present invention is to provide a lithium secondary battery having improved discharge capacity, initial efficiency and output characteristics by providing the negative electrode of the present invention.
  • the heat treatment of the silicon-based composite precursor, to form a silicon-based composite comprising an amorphous carbon coating layer containing one or more amorphous silicon particles therein (S5); provides a method for producing a negative electrode active material for a lithium secondary battery comprising a. .
  • the amorphous silicon layer deposition step (S1) is 10 sccm / 60min silane gas at a temperature of 500 °C to 700 °C and 10 -8 Torr to 760 Torr (1 atmosphere), specifically 10 -2 Torr to 760 Torr It can be carried out while adding at a rate of from 50 sccm / 60 min.
  • the thickness of the deposited amorphous silicon layer is 20nm to 500nm.
  • the amorphous silicon layer crushing step (S2) is immersed in the acetone solution a glass substrate on which an amorphous silicon layer is deposited, and then pulverized for 10 minutes to 20 minutes at room temperature with an output between 50W and 200W using an ultrasonic grinder. It can be carried out.
  • the method of the present invention may further include preparing the amorphous silicon particles, and then collecting the pulverized amorphous silicon particles by volatilizing an acetone solvent.
  • the average particle diameter (D50) of the pulverized amorphous silicon particles is 5nm to 500nm.
  • the dispersion solution manufacturing step (S3) may be carried out by mixing carbonizable carbon-based materials in distilled water at a temperature of 1000 ° C. or less to prepare a carbon-based precursor solution, and then dispersing amorphous silicon particles.
  • the carbon-based precursor solution may be used from 25 parts by weight to 4,000 parts by weight based on 100 parts by weight of amorphous silicon particles.
  • At the time of dispersing the amorphous silicon particles at the time of dispersing the amorphous silicon particles, at least one conductive carbon-based material selected from the group consisting of crystalline and amorphous carbon may be dispersed together.
  • the conductive carbonaceous material may be used in an amount of 0.99 parts by weight to 1900 parts by weight based on 100 parts by weight of amorphous silicon particles.
  • the precursor solution may be supplied into a spray device to form a droplet by spraying, and then the drying of the droplet may be simultaneously performed.
  • the spray drying step may be carried out at a rate of 10 mL / min to 50 mL / min at about 50 °C to 300 °C.
  • step (S5) of the heat treatment of the silicon-based composite precursor may be performed at 400 °C to 1000 °C temperature, for about 10 minutes to 1 hour.
  • Amorphous carbon coating layer provides a negative electrode active material for a lithium secondary battery comprising a silicon composite consisting of one or more amorphous silicon particles contained in the amorphous carbon coating layer.
  • the amorphous silicon particles may include single amorphous particles or secondary amorphous silicon particles formed by aggregation of primary amorphous silicon particles formed of the single particles.
  • the amorphous silicon particles may be uniformly dispersed in the amorphous carbon coating layer.
  • the amorphous silicon particles may be included in an amount of 1 to 95% by weight, and specifically 5 to 90% by weight, based on the total weight of the negative electrode active material.
  • the weight ratio of the amorphous silicon particles to the amorphous carbon coating layer may be 1:99 to 95: 5, specifically 5:95 to 90:10.
  • the anode active material may further include at least one conductive carbon-based material selected from the group consisting of crystalline or amorphous carbon different from the amorphous carbon layer forming material in the amorphous carbon coating layer.
  • the negative electrode active material is an amorphous carbon coating layer; And it may include a silicon composite consisting of one or more amorphous silicon particles and amorphous carbon contained in the amorphous carbon coating layer.
  • the negative electrode active material is an amorphous carbon coating layer;
  • one or more amorphous silicon particles and crystalline carbon contained in the amorphous carbon coating layer, and the silicon composite may include the one or more amorphous silicon particles distributed on the surface of the crystalline carbon.
  • the conductive carbon-based material may be included in an amount of 0.1 wt% to 90 wt% based on the total weight of the negative electrode active material. Specifically, when the conductive carbon-based material is amorphous carbon, it may be included in an amount of 0.1% to 50% by weight based on the total weight of the negative electrode active material, and when the conductive carbon-based material is crystalline carbon, based on the total weight of the negative electrode active material 10 wt% to 90 wt% may be included.
  • a negative electrode comprising a current collector and a negative electrode active material produced by the method of the present invention formed on at least one surface of the current collector.
  • an embodiment of the present invention provides a lithium secondary battery having the negative electrode.
  • amorphous silicon particles for the negative electrode active material in which oxidation is prevented and crystallinity is controlled during the production of the nano silicon particles.
  • amorphous silicon particles it is possible to manufacture a negative electrode active material and a negative electrode including the same, the electrode thickness expansion phenomenon is reduced than when using the crystalline silicon particles.
  • a lithium secondary battery having improved initial efficiency, reversible capacity, and lifetime characteristics can be manufactured.
  • Example 1 is a schematic diagram of a negative electrode active material for a lithium secondary battery including the silicon composite prepared in Example 1 of the present invention.
  • Example 2 is a schematic view of a negative electrode active material for a lithium secondary battery including the silicon composite prepared in Example 2 of the present invention.
  • Example 3 is a schematic diagram of a negative electrode active material for a lithium secondary battery including the silicon composite prepared in Example 3 of the present invention.
  • a silicon-based negative electrode active material has been proposed as a negative electrode active material for a lithium secondary battery, but the silicon-based negative electrode active material is a nonconductor, and due to the rapid volume change that occurs during the charging and discharging process, crushing of the negative electrode active material particles occurs or an unstable SEI.
  • Solid Electrolyte Interface has a disadvantage in that the battery performance is reduced by forming a layer.
  • the brittle carbon has a problem of being broken by volume expansion of silicon generated during charge and discharge.
  • a method for preparing a nano-sized silicon-based powder has been developed, but as the silicon-based material is oxidized during the grinding process, another problem may occur that the initial efficiency is reduced.
  • amorphous silicon layer by depositing an amorphous silicon layer, and then performing an ultrasonic grinding, it is possible to provide a method for producing a negative electrode active material that can be used to prepare amorphous silicon particles that can easily control the crystallinity and prevent oxidation during the manufacturing process. Can be.
  • this as a negative electrode active material it is possible to manufacture a lithium secondary battery with improved initial efficiency, life characteristics and electrode thickness expansion characteristics.
  • the present invention in one embodiment
  • the heat treatment of the silicon-based composite precursor, to form a silicon composite comprising an amorphous carbon coating layer including one or more amorphous silicon particles therein (S5); provides a method for producing a negative electrode active material for a lithium secondary battery comprising a.
  • the amorphous silicon layer deposition step (S1) is 700 °C or less, specifically 500 °C to 700 °C temperature and 10 -8 Torr to 760 Torr (1 atm), specifically 10 -2 Torr
  • the silane gas may be carried out at a rate of 10 sccm / 60 min to 50 sccm / 60 min under a pressure condition of 760 Torr.
  • the bonding force between the silicon elements is weak, and thin enough to be easily broken in the ultrasonic grinding step described later.
  • a thick amorphous silicon layer can be deposited. If the silane gas is added at a temperature below 500 ° C., an amorphous silicon layer may not be deposited. On the other hand, when silane gas is added at a temperature above 700 ° C., crystal growth of silicon-based particles may be increased to form a crystalline silicon layer.
  • the method of the present invention by performing a chemical vapor deposition method in a low temperature range, crystal growth of silicon particles can be suppressed to form an amorphous silicon layer.
  • the nanoparticles have an advantage of excellent life characteristics and small volume expansion compared to the crystalline silicon layer.
  • the amorphous silicon layer may be deposited to a thickness of about 20nm to 500nm.
  • the deposition thickness of the amorphous silicon layer is less than 20 nm, when the subsequent ultrasonic grinding process is performed, the particle size of the collected silicon particles is very small, and the specific surface area is increased, thereby decreasing initial efficiency. On the other hand, when the deposition thickness of the amorphous silicon layer exceeds 500nm, it may be difficult to proceed with the subsequent ultrasonic grinding process stable.
  • the amorphous silicon layer grinding step (S2) is impregnated in the beaker containing acetone, the glass substrate on which the amorphous silicon layer is deposited, and then outputs 50 W to 200 W using an ultrasonic grinder.
  • Ultrasonic grinding may be performed at room temperature for 10 to 20 minutes. At this time, even if it is possible to grind
  • the amount of acetone used may be largely independent of the thickness ratio of the silicon layer, but may be used to the extent that the glass substrate on which the amorphous silicon layer is deposited is completely impregnated with acetone.
  • the drying process should proceed at the lowest possible temperature, for this purpose, it is preferable to use a solvent that is highly volatile even at low temperatures such as acetone during the ultrasonic grinding process.
  • a solvent that is highly volatile even at low temperatures such as acetone during the ultrasonic grinding process.
  • an organic solvent having high volatility may be used even at a low temperature such as ethanol or methanol.
  • the processing time is long, and the temperature may increase due to the friction between the particles during the grinding process.
  • the oxidation of the silicon particles may occur due to the reaction of surrounding oxygen or moisture with silicon particles.
  • the method of the present invention by depositing an amorphous silicon layer and then performing an ultrasonic grinding, not only can the amorphous silicon layer be ground in a short time at low temperature, but also the ultrasonically pulverized amorphous silicon particles Since the process of collecting is carried out, it is possible to prevent the problem that silicon grains grow or silicon particles are oxidized during the grinding process.
  • the method of the present invention may include the step of collecting the pulverized amorphous silicon particles by volatilizing acetone solvent after the completion of the ultrasonic grinding process.
  • the average particle diameter (D50) of the amorphous silicon particles obtained by the method of the present invention may be 5nm to 500nm, specifically 20nm to 200nm.
  • the average particle diameter of the amorphous silicon particles is less than 5 nm, the specific surface area may be too large, resulting in loss of reversible capacity. If the average particle diameter is larger than 500 nm, the particle size is large and the volume expansion becomes severe when reacting with lithium ions. The efficiency of buffering the volume expansion of the negative electrode active material is inferior.
  • the negative electrode active material reacts with the electrolyte during filling to form a protective film called an SEI film on the surface of the particle.
  • the SEI film does not decompose well once produced.
  • the SEI film may be broken by the volume change or crack of the negative electrode active material, or by heat or impact applied externally. In this case, when the electrode surface is exposed to the electrolyte, the SEI film may be regenerated. If the average particle diameter (D50) of the single silicon particles exceeds 500 nm, since cracks are repeatedly generated due to charge and discharge, the volume increases as the SEI film is repeatedly generated. As such, an increase in the volume of the silicon particles will soon lead to an increase in the volume of the final anode active material particles.
  • D50 average particle diameter
  • dispersion solution preparation step (S3) to prepare a carbon-based precursor solution by mixing a carbonaceous carbon material at a temperature of 1000 °C or less in distilled water, and then to disperse amorphous silicon particles Can be carried out in stages.
  • It can be prepared by mixing the distilled water: carbon-based material in a weight ratio of approximately 1: 2 to 10: 1.
  • the carbonaceous material which can be carbonized even at a low temperature of 1000 ° C. or lower may include a single substance or a mixture of two or more selected from the group consisting of sucrose, glucose, fructose, galactose, maltose, and lactose. Sucrose may be carbonized at a relatively low temperature.
  • the carbon-based precursor solution may be used from 25 parts by weight to 4,000 parts by weight based on 100 parts by weight of amorphous silicon particles. If the amount of the carbon-based precursor solution is less than 25 parts by weight, the viscosity of the amorphous silicon particles / carbon-based precursor solution is not easy to perform a spray process, when the amount of the carbon-based precursor solution exceeds 4,000 parts by weight, The content of amorphous silicon particles in the dispersion solution is so low that the role as a high capacity negative electrode material can be reduced.
  • the amorphous carbon is preferably a material different from the amorphous carbon layer forming material as described above.
  • the negative electrode active material of the present invention may further include a conductive carbon-based material to supplement the low conductivity of the silicon particles or to implement the role of the structural support when secondary particles are formed.
  • the conductive carbonaceous material may be dispersed in a range of 0.99 parts by weight to 1,900 parts by weight based on 100 parts by weight of amorphous silicon particles.
  • the amount of the conductive carbonaceous material is less than 0.99 parts by weight, the conductivity does not improve or serve as a structural support, and if the amount exceeds 1,900 parts by weight, the silicon-based active material content is reduced, the discharge capacity per weight (mAh / g Since) decreases, there is no advantage in terms of discharge capacity of the final active material.
  • the conductive carbon-based material is not particularly limited as long as it is a crystalline or amorphous carbon having conductivity without causing chemical change in the battery.
  • the crystalline carbon may include natural graphite, artificial graphite, graphene, or the like.
  • the amorphous carbon a single material or a mixture of two or more selected from the group consisting of hard carbon, soft carbon, carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and carbon nanofibers may be used. have.
  • the average particle diameter (D50) of the natural graphite or artificial graphite particles of the crystalline carbon may be 300nm to 30 ⁇ m.
  • the average particle diameter of the natural or artificial graphite particles is less than 300 nm, the role as a structural support may be reduced.
  • the average particle diameter of the natural or artificial graphite particles is greater than 30 ⁇ m, the average particle diameter of the final negative electrode active material is increased, making the coating process difficult in manufacturing a secondary battery. The disadvantage is that you can.
  • the negative electrode active material of the present invention may optionally add a single material selected from the group consisting of metal fibers, metal powders, zinc oxide, potassium titanate, titanium oxide, and polyphenylene derivatives, or two or more of these conductive materials. It can be included as.
  • the spray drying step (S4) for preparing a silicon-based composite precursor is supplied to the precursor solution into a spray device to form a droplet by spraying, and then the step of drying the droplet simultaneously Can be performed.
  • the spraying step may be carried out using a drying method including rotary spraying, nozzle spraying, ultrasonic spraying, or a combination thereof, from 10 mL / min to 50 mL / min at a temperature of about 50 ° C to 300 ° C, specifically 80 ° C to 250 ° C. Can be done at speed.
  • a drying method including rotary spraying, nozzle spraying, ultrasonic spraying, or a combination thereof, from 10 mL / min to 50 mL / min at a temperature of about 50 ° C to 300 ° C, specifically 80 ° C to 250 ° C. Can be done at speed.
  • the liquid crystal state and drying of the solvent is stably made when the spray drying within the temperature and speed range.
  • the average particle diameter (D50) of the amorphous silicon particles included in the present invention is 5 nm to 500 nm
  • the average particle diameter (D50) of the amorphous carbon particles is about 100 nm to 300 nm
  • the average particle diameter (D50) of the crystalline carbon particles is 300 nm.
  • the above is specifically several micrometers-30 micrometers. Therefore, in the spraying step, when the amorphous silicon particles and the amorphous carbon particles are sprayed together and complexed, the two particles do not have a large difference in average particle diameter, so that the amorphous silicon particles and the amorphous carbon particles are formed inside the final active material as shown in FIG. 2. It is produced in a form of even distribution.
  • the surface of the crystalline carbon particles may be prepared in a shape such that amorphous silicon particles are coated.
  • the step (S5) of heat treating the silicon-based composite precursor is at a temperature of 400 °C to 1000 °C, preferably 500 °C to 800 °C, about 10 minutes to 1 hour, preferably 20 It may be from minutes to 1 hour.
  • the heat treatment temperature is less than 400 ° C., the temperature is so low that the carbonization process does not occur sufficiently, making it difficult to form an amorphous carbon coating layer. If the temperature exceeds 1000 ° C., the crystallinity of the amorphous carbon coating layer included in the precursor is increased. There is a problem.
  • the heat treatment step is preferably performed in an inert atmosphere in which nitrogen gas, argon gas, helium gas, krypton gas, or xenon gas is present.
  • anode active material 10 for a lithium secondary battery including a silicon composite including one or more amorphous silicon particles 1 included in the amorphous carbon coating layer 5 (see FIG. 1).
  • the amorphous silicon particles included in the amorphous carbon coating layer may include secondary amorphous silicon particles formed by agglomeration of the single particles or primary amorphous silicon particles formed of the single particles.
  • the amorphous silicon particles may be uniformly dispersed in the amorphous carbon coating layer.
  • the average particle diameter of the amorphous silicon particles may be 5nm to 500nm, specifically 20nm to 200nm.
  • the amorphous silicon particles may be included in an amount of 1 to 95% by weight, and specifically 5 to 90% by weight, based on the total weight of the negative electrode active material.
  • the weight ratio of the at least one amorphous silicon particle: amorphous carbon coating layer may be in the range of 5:90 to 90:10, specifically 10:90 to 80:20.
  • the negative electrode active material may further include at least one conductive carbon-based material selected from the group consisting of crystalline or amorphous carbon different from forming the amorphous carbon coating layer inside the amorphous carbon coating layer.
  • the conductive carbon-based material may be included in an amount of 0.1 wt% to 90 wt% based on the total weight of the negative electrode active material.
  • An amorphous carbon coating layer 15 provides a negative electrode active material 50 for a lithium secondary battery comprising a silicon composite consisting of one or more amorphous silicon particles 11 and amorphous carbon 13 contained in the amorphous carbon coating layer (see FIG. 2).
  • the amorphous carbon may be included in 0.1 to 50% by weight based on the total weight of the negative electrode active material.
  • the content of the amorphous carbon is less than 0.1% by weight, it is difficult to describe the effect of improving the electrical conductivity by adding the conductive carbonaceous material, and when the content exceeds 50% by weight, the reversible capacity of the final negative electrode active material is lowered.
  • the crystalline carbon may include spherical / plate-shaped natural graphite or artificial graphite particles.
  • the average particle diameter (D50) of the crystalline carbon is 300 nm to 30 ⁇ m.
  • the average particle diameter of the crystalline carbon is less than 300 nm, the role as a structural support may be reduced, and if the average particle diameter exceeds 30 ⁇ m, the average particle size of the final negative electrode active material is increased to perform a uniform coating process in manufacturing a secondary battery. It can be difficult.
  • the crystalline carbon may be included in 10 to 90% by weight based on the total weight of the negative electrode active material.
  • the content of the crystalline carbon is less than 10% by weight, it is difficult to expect the effect of improving the electrical conductivity and the role of the structural support by adding crystalline carbon, when the content of the crystalline carbon exceeds 90% by weight of the reversible capacity of the final negative electrode active material There is a problem of being lowered.
  • the average particle diameter (D50) of the negative electrode active material of the present invention is 50nm to 35 ⁇ m.
  • the average particle diameter (D50) of the negative electrode active material is 50 nm to 30 ⁇ m
  • the average particle diameter (D50) of the negative electrode active material is 500 nm to 35 ⁇ m.
  • the average particle diameter of the negative electrode active material is within the above range, it is possible to reduce the stress of the silicon due to volume expansion generated during charging and discharging of the negative electrode active material, to increase the reversible capacity, and to inhibit the volume expansion during reaction with lithium, thereby improving cycle life. Characteristics are improved. If the average particle diameter of the negative electrode active material is less than 50 nm, the specific surface area is too large to cause a loss of reversible capacity. If the average particle diameter exceeds 35 ⁇ m, cracking and crushing of the negative electrode active material itself occurs very easily due to the stress caused by volume expansion. As the particle size is large, the volume expansion becomes severe upon reaction with lithium, thereby decreasing efficiency in buffering the volume expansion of the whole spherical particles.
  • the specific surface area (BET) of the negative electrode active material of the present invention may be 0.5 m 2 / g to 20 m 2 / g. In this case, when the specific surface area exceeds 20 m 2 / g, an irreversible reaction between the electrolyte and lithium ions occurs on the surface of the active material during charge and discharge, thereby causing consumption of lithium ions, which may cause initial efficiency reduction.
  • the negative electrode active material made of the composite including the amorphous silicon particle-amorphous carbon coating layer prepared by the method of the present invention can lower the overall process temperature to prevent the crystalline growth and oxidation of the silicon particles, the conventional crystalline Compared to the silicon-based nanoparticle-carbon composites, there is an advantage in that the life and volume expansion characteristics are excellent, and the initial efficiency is superior to the general crystalline silicon-based nanoparticle-carbon composites.
  • the initial efficiency is superior to the conventional crystalline silicon-based nanoparticles-carbon composites, the discharge capacity (mAh / g) compared to the conventional crystalline silicon-based nanoparticles-carbon composites
  • the discharge capacity (mAh / g) compared to the conventional crystalline silicon-based nanoparticles-carbon composites
  • the discharge capacity of the graphite itself is 360 mAh / g, which is not large compared to silicon, and when the amount of silicon compounded to increase the discharge capacity is increased, silicon particles are concentrated on the graphite surface. It may cause deterioration of lifespan characteristics.
  • the composite produced by the method of the present invention can evenly distribute the silicon particles in the carbon matrix to prevent degradation of life characteristics.
  • the negative electrode active material produced by the method of the present invention further includes a conductive material such as graphite particles or a conductive material therein, thereby further realizing a conductivity improving effect.
  • It provides a negative electrode comprising the negative electrode active material of the present invention formed on at least one surface of the current collector.
  • the negative electrode according to an embodiment of the present invention can be prepared by a conventional method known in the art.
  • a slurry is prepared by selectively mixing and stirring a solvent, a binder, and a conductive material in the negative electrode active material, if necessary, and then applying (coating) to a current collector of a metal material, compressing, and drying to prepare a negative electrode.
  • a slurry is prepared by selectively mixing and stirring a solvent, a binder, and a conductive material in the negative electrode active material, if necessary, and then applying (coating) to a current collector of a metal material, compressing, and drying to prepare a negative electrode.
  • the binder is used to bind the negative electrode active material particles to maintain the molded body, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), styrene butadiene rubber Binders) are used.
  • PTFE polytetrafluoroethylene
  • PVdF polyvinylidene fluoride
  • styrene butadiene rubber Binders styrene butadiene rubber Binders
  • the conductive material is natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon nanotube, fullerene, carbon fiber, metal Fiber, carbon fluoride, aluminum, nickel powder, zinc oxide, potassium titanate, titanium oxide and polyphenylene derivatives may be any one selected from the group consisting of, or a mixture of two or more thereof, preferably carbon black.
  • the negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery.
  • copper, stainless steel, aluminum, nickel, titanium, calcined carbon, Surface treated with carbon, nickel, titanium, silver, or the like on the surface of copper or stainless steel, aluminum-cadmium alloy, etc. may be used.
  • the negative electrode current collector may have a thickness of about 3 to 500 ⁇ m, and like the positive electrode current collector, fine concavities and convexities may be formed on the surface of the current collector to enhance the bonding force of the negative electrode active material.
  • it can be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven body.
  • a lithium secondary battery including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode and a non-aqueous electrolyte in which lithium salt is dissolved.
  • the positive electrode and the electrolyte used may be a material commonly used in the art, but is not limited thereto.
  • the positive electrode may be prepared by coating a positive electrode slurry including a positive electrode active material, a binder, a conductive material, a solvent, and the like on a positive electrode current collector, followed by drying and rolling.
  • the positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and may specifically include a lithium composite metal oxide containing lithium and one or more metals such as cobalt, manganese, nickel or aluminum. have. More specifically, the lithium composite metal oxide is a lithium-manganese oxide (eg, LiMnO 2 , LiMn 2 O 4, etc.), lithium-cobalt oxide (eg, LiCoO 2, etc.), lithium-nickel oxide (for example, LiNiO 2 and the like), lithium-nickel-manganese-based oxide (for example, LiNi 1-Y Mn Y O 2 (where, 0 ⁇ Y ⁇ 1), LiMn 2-z Ni z O 4 ( here, 0 ⁇ Z ⁇ 2) and the like), lithium-nickel-cobalt oxide (e.g., LiNi 1-Y1 Co Y1 O 2 (here, 0 ⁇ Y1 ⁇ 1) and the like), lithium-manganese-cobal
  • LiCoO 2 , LiMnO 2 , LiNiO 2 , and lithium nickel manganese cobalt oxides may be improved in capacity and stability of the battery.
  • lithium nickel cobalt aluminum oxide e.g., Li (Ni 0. 8 Co 0. 15 Al 0 .
  • the lithium composite metal oxide is Li (Ni 0.6 Mn 0.2 Co 0.2 ) O 2 , Li (Ni 0.5 Mn 0.3 Co 0.2 ) O 2 , Li (Ni 0.7 Mn 0.15 Co 0.15 ) O 2, or Li (Ni 0.8 Mn 0.1 Co 0.1 ) O 2 , and the like, and any one or a mixture of two or more thereof may be used. have.
  • the cathode active material may be included in an amount of 80 wt% to 99 wt% based on the total weight of the cathode slurry.
  • the conductive material is typically added at 1 to 30% by weight based on the total weight of the positive electrode slurry.
  • a conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include graphite; Carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.
  • conductive materials include Chevron Chemical Company, Denka Singapore Private Limited, Gulf Oil Company, Ketjenblack and EC, which are acetylene black series. Family (Armak Company), Vulcan XC-72 (manufactured by Cabot Company) and Super P (manufactured by Timcal).
  • the binder is a component that assists in bonding the active material and the conductive material and bonding to the current collector, and is generally added in an amount of 1 to 30 wt% based on the total weight of the positive electrode slurry.
  • binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, Polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluorine rubber, various copolymers, and the like.
  • the solvent may include an organic solvent such as N-methyl-2-pyrrolidone (NMP), and may be used in an amount that becomes a desirable viscosity when including the cathode active material, and optionally a binder and a conductive material.
  • NMP N-methyl-2-pyrrolidone
  • the concentration of the positive electrode active material and, optionally, the solid content including the binder and the conductive material may be included in an amount of 50 wt% to 95 wt%, preferably 70 wt% to 90 wt%.
  • the electrolyte is commonly used in manufacturing a lithium secondary battery, and includes a non-aqueous organic solvent and a lithium salt.
  • the non-aqueous organic solvent is not particularly limited as long as it can minimize decomposition by an oxidation reaction or the like in the process of charging and discharging a battery, and can exhibit desired properties with an additive.
  • examples thereof include a carbonate-based compound or propio. Nate type compounds etc. can be used individually, or can mix and use 2 or more types.
  • Examples of such carbonate compounds include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), Ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) and vinylene carbonate (VC), any one selected from the group consisting of, or a mixture of two or more thereof.
  • DMC dimethyl carbonate
  • DEC diethyl carbonate
  • DPC dipropyl carbonate
  • MPC methylpropyl carbonate
  • EPC ethylpropyl carbonate
  • MEC methylethyl carbonate
  • Ethylene carbonate EC
  • PC butylene carbonate
  • BC butylene carbonate
  • VC vinylene carbonate
  • propionate-based compound may be ethyl propionate (EP), propyl propionate (PP), n-propyl propionate, iso-propyl propionate, n-butyl propionate, iso One or a mixture of two or more selected from the group consisting of -butyl propionate and tert-butyl propionate.
  • non-aqueous organic solvent for example, N-methyl-2-pyrrolidone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2 Dimethoxy ethane, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolon, formamide, dimethylformamide, dioxolon, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester , Trimethoxy methane, dioxorone derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ether, methyl propionate, ethyl propionate and the like Can be.
  • N-methyl-2-pyrrolidone propylene carbonate,
  • the anion wherein the lithium salt comprises a Li + cation are F -, Cl -, Br - , I -, NO 3 -, N (CN) 2 -, BF 4 -, ClO 4 -, AlO 4 -, AlCl 4 -, PF 6 -, SbF 6 -, AsF 6 -, BF 2 C 2 O 4 -, BC 4 O 8 -, (CF 3) 2 PF 4 -, (CF 3) 3 PF 3 -, (CF 3) 4 PF 2 - , (CF 3) 5 PF -, (CF 3) 6 P -, CF 3 SO 3 -, C 4 F 9 SO 3 -, CF 3 CF 2 SO 3 -, (CF 3 SO 2) 2 N -, ( F 2 SO 2) 2 N -, CF 3 CF 2 (CF 3) 2 CO -, (CF 3 SO 2) 2 CH -, CF 3 (CF 2) 7 SO 3 -, CF 3 CO 2
  • the said lithium salt can also be used 1 type or in mixture of 2 or more types as needed.
  • the lithium salt may be appropriately changed within a range generally available, but may be included in an electrolyte solution at a concentration of 0.8 M to 1.5 M in order to obtain an effect of forming an anti-corrosion coating on the surface of the electrode.
  • the lithium secondary battery according to the exemplary embodiment of the present invention may include all conventional lithium secondary batteries, such as a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.
  • the external shape of the lithium secondary battery of the present invention is not particularly limited, but may be cylindrical, square, pouch type or coin type using a can.
  • the lithium secondary battery of the present invention can be used as a power source for various electronic products.
  • the present invention may be used in a portable telephone, a mobile phone, a game console, a portable television, a laptop computer, a calculator, and the like, but is not limited thereto.
  • Silane gas was added at a rate of 25 sccm / 60 min under a pressure condition of 500 ° C. and 760 Torr to deposit an amorphous silicon layer having a thickness of 100 nm on the surface of the glass substrate.
  • the glass substrate on which the amorphous silicon layer is deposited is impregnated in a beaker containing acetone, and then subjected to ultrasonic grinding for 10 minutes at room temperature at 100W output using an ultrasonic mill, thereby obtaining amorphous silicon particles having an average particle diameter (D50) of 100 nm.
  • D50 average particle diameter
  • sucrose 120 g was dissolved in 1 L of distilled water to prepare a carbon-based precursor solution, and then 50 g of the pulverized amorphous silicon particles were dispersed to prepare a dispersion solution.
  • the dispersion solution was spray dried at a rate of 20 mL / min at 220 ° C. to prepare a silicon-based composite precursor.
  • the silicon-based composite precursor was heat-treated at 600 ° C. for 15 minutes, and the average particle diameter (D5) including amorphous silicon particles 1 (50% by weight) inside the amorphous carbon coating layer 5 (50% by weight).
  • a 5 ⁇ m lithium secondary battery negative electrode active material 10 was prepared (see FIG. 1).
  • Example 2 When dispersing the pulverized amorphous silicon particles in the carbon-based precursor solution in Example 1, in the same manner as in Example 1, except that 2g of carbon black which is amorphous carbon is dispersed together to prepare a dispersion solution, amorphous Cathode active material for lithium secondary battery having an average particle diameter (D5) of 5 ⁇ m including amorphous silicon particles 11 (49 wt%) and conductive material 13 (2 wt%) in the carbon coating layer 15 (49 wt%). 50 was prepared (see FIG. 2).
  • Example 2 When dispersing the pulverized amorphous silicon particles in the carbon-based precursor solution in Example 1, in the same manner as in Example 1 except for dispersing the artificial graphite particles of crystalline carbon together to prepare a dispersion solution, A lithium secondary battery having an average particle diameter (D5) of 21 ⁇ m including amorphous silicon particles 111 (17 wt%) and graphite particle core 117 (66 wt%) inside an amorphous carbon coating layer 115 (17 wt%). A negative electrode active material 100 was prepared.
  • D5 average particle diameter of 21 ⁇ m including amorphous silicon particles 111 (17 wt%) and graphite particle core 117 (66 wt%) inside an amorphous carbon coating layer 115 (17 wt%).
  • a negative electrode active material 100 was prepared.
  • Nano-size crystalline silicon particles were prepared by pulverizing silicon powder (Sigma-aldrich) having an average particle diameter of 44 ⁇ m using a ball mill method. At this time, a zirconia ball having a diameter of 3mm was used as the milling media, and the ratio of the ball and the silicon powder was mixed in a 1: 1 mass ratio and pulverized for 2 hours. The average particle diameter of the crystalline silicon particles after grinding was 150 nm.
  • sucrose was dissolved in 1 L of distilled water to prepare a carbon-based precursor solution, and then 50 g of the pulverized crystalline silicon particles were dispersed to prepare a dispersion solution.
  • the dispersion solution was spray dried at a rate of 20 mL / min at 220 ° C. to prepare a silicon-based composite precursor.
  • the silicon-based composite precursor was heat-treated at 600 ° C. for 15 minutes to have an average particle diameter (D5) of 5 ⁇ m including amorphous silicon particles (50%) inside the amorphous carbon coating layer (50%) inside the amorphous carbon coating layer (50%).
  • D5 average particle diameter
  • a negative electrode active material for a lithium secondary battery was prepared.
  • the amorphous carbon coating layer ( 49%) to prepare a negative active material for a lithium secondary battery having an average particle diameter (D5) of 5 ⁇ m including amorphous silicon particles (49%) and carbon black (2%).
  • the negative electrode active material prepared in Example 1 as a negative electrode active material, acetylene black as a conductive material, styrene-butadiene rubber (SBR) as a binder, and carboxymethyl cellulose (CMC) as a thickener were mixed in a weight ratio of 96: 1: 2: 1. And, these were mixed with water (H 2 O) as a solvent to prepare a uniform negative electrode active material slurry.
  • the prepared negative electrode active material slurry was coated on one surface of a copper current collector to a thickness of 65 ⁇ m, dried and rolled, and then punched to a predetermined size to prepare a negative electrode.
  • Lithium metal foil was used as a counter electrode for the negative electrode.
  • a lithium secondary battery was manufactured in the same manner as in Example 4, except that the negative electrode active material prepared in Example 2 was used instead of the negative electrode active material prepared in Example 1 as the negative electrode active material.
  • a lithium secondary battery was manufactured in the same manner as in Example 4, except that the anode active material prepared in Example 3 was used instead of the anode active material prepared in Example 1 as the anode active material.
  • a lithium secondary battery was manufactured in the same manner as in Example 4, except that the negative electrode active material prepared in Comparative Example 1 was used as the negative electrode active material.
  • a lithium secondary battery was manufactured by the same method as Comparative Example 4, except that the negative electrode active material prepared in Comparative Example 2 was used as the negative electrode active material.
  • a lithium secondary battery was manufactured by the same method as Comparative Example 4, except that the negative electrode active material prepared in Comparative Example 3 was used as the negative electrode active material.
  • Oxygen analysis was performed on the negative electrode active materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3 using the CS-800 equipment of ELTRA, and the specific surface area was measured using the BELSORP-max equipment of BEL JAPAN. It was.
  • the silicon grain size present in the negative electrode active materials of Examples 1 to 3 and the silicon grain size present in the negative electrode active materials of Comparative Examples 1 to 3 were measured through Bruker's D4 Endeavor XRD equipment. The results are shown in Table 1.
  • the silicon grain size contained in the negative electrode active material is small, it is known that the electrode volume expansion rate is low.
  • the negative electrode active material of Comparative Examples 1 to 3 including silicon particles obtained by grinding a commercially available bulk silicon powder by a ball mill process as shown in Table 1 after grinding according to the silicon grain size of the bulk silicon powder, Silicon grains of about 17 nm to 19 nm in size.
  • the negative electrode active material of Examples 1 to 3 including amorphous silicon particles prepared by ultrasonic grinding compared to the negative electrode active material of Comparative Examples 1 to 3, the silicon grains of 4.3 nm or less are included. Therefore, in the case of the electrode including the negative electrode active material of Examples 1 to 3 of the present invention, it can be predicted that the volume expansion ratio is reduced.
  • the secondary battery of Example 4 increased the initial efficiency by 10% and the discharge capacity by about 210 mAh / g, compared to the secondary battery of Comparative Example 4.
  • the secondary battery of Example 5 had an initial efficiency of 9% and a discharge capacity of about 210 mAh / g.
  • the secondary battery of Example 6 increased the initial efficiency by 9% and the discharge capacity by about 80 mAh / g.
  • the negative electrode active materials of Comparative Examples 4 to 6 including silicon particles prepared by pulverizing the bulk silicon powder are oxidized by frictional heat during grinding, and irreversible phase during initial charging as oxygen is bonded to the silicon particles. Since a phase formed by an irreversible reaction, which is produced during the discharge but is not decomposed again during discharge, is formed, the initial efficiency is lowered and the amount of silicon atoms that can participate in the reversible reaction is reduced. Therefore, as shown in Table 2, the charge and discharge reversible capacity of the secondary batteries of Comparative Examples 4 to 6 including the negative electrode active materials of Comparative Examples 1 to 3 is reduced.
  • the life characteristics are about 8% superior to the secondary battery life characteristics of Comparative Example 4.
  • the life characteristics of the secondary battery of Example 5 of the present invention are about 9% superior to those of the secondary battery of Comparative Example 5.
  • the life characteristics of the secondary battery of Example 6 of the present invention are about 6% superior to those of the secondary battery of Comparative Example 6.
  • the electrode thickness expansion ratio of the 51st cycle charged state of the secondary batteries of Examples 4 to 6 is significantly lower than that of each of the secondary batteries of Comparative Examples 4 to 6.

Abstract

The present invention relates to: a method for preparing an anode active material for a secondary battery, the anode active material being capable of preventing oxidation during the preparation of nano-sized silicon particles; an anode active material for a secondary battery, prepared by the method; an anode for a secondary battery, comprising the anode active material for a secondary battery; and a lithium secondary battery.

Description

리튬 이차전지용 음극활물질의 제조 방법 및 이를 적용한 리튬 이차전지Manufacturing method of negative electrode active material for lithium secondary battery and lithium secondary battery using same
관련 출원(들)과의 상호 인용Cross Citation with Related Application (s)
본 출원은 2015년 12월 10일자 한국 특허출원 제10-2015-0176259호, 제10-2015-0176263호, 및 제10-2015-0176265호와, 2016년 12월 8일자 한국 특허 출원 제10-2016-0166995호에 기초한 우선권의 이익을 주장하며, 해당 한국 특허 출원의 문헌에 개시된 모든 내용은 본 명세서의 일부로서 포함된다.The present application is filed with Korean Patent Application Nos. 10-2015-0176259, 10-2015-0176263, and 10-2015-0176265, issued Dec. 10, 2015, and Korean Patent Application No. 10-Dec. 8, 2016. Claiming the benefit of priority based on 2016-0166995, all the contents disclosed in the literature of that Korean patent application are incorporated as part of this specification.
기술분야Technical Field
본 발명은 리튬 이차전지용 음극활물질의 제조 방법 및 이를 적용한 리튬 이차전지에 관한 것이다. The present invention relates to a method for producing a negative electrode active material for a lithium secondary battery, and a lithium secondary battery using the same.
최근 정보 통신 산업의 발전에 따라 전자 기기가 소형화, 경량화, 박형화 및 휴대화됨에 따라, 이러한 전자 기기의 전원으로 사용되는 전지의 고에너지 밀도화에 대한 요구가 높아지고 있다. In recent years, as the electronic devices become smaller, lighter, thinner, and portable with the development of the information and communication industry, the demand for high energy density of batteries used as power sources for such electronic devices is increasing.
리튬 이차전지는 이러한 요구를 가장 잘 충족시킬 수 있는 충방전 가능한 전지로서, 현재 소형비디오 카메라, 휴대전화, 노트북 등의 휴대용 전자기기 및 통신기기 등에 이용되고 있다.Lithium secondary batteries are chargeable and dischargeable batteries that can best meet these requirements, and are currently used in portable electronic devices and communication devices such as small video cameras, mobile phones, and notebook computers.
일반적으로 리튬 이차전지는 양극, 음극, 전해질로 구성되며, 첫 번째 충전에 의해 양극활물질로부터 나온 리튬 이온이 음극활물질, 즉 카본 입자 내에 삽입되고 방전시 다시 탈리되는 등, 양극 및 음극의 양쪽 전극을 왕복하면서 에너지를 전달하는 역할을 하기 때문에 충방전이 가능하게 된다.In general, a lithium secondary battery is composed of a positive electrode, a negative electrode, and an electrolyte, and lithium ions from the positive electrode active material are inserted into the negative electrode active material, that is, carbon particles, and desorbed again when discharged. Since it plays a role of transferring energy while reciprocating, charge and discharge are possible.
한편, 휴대용 전자기기의 발달로 인하여 고용량의 전지가 계속 요구됨에 따라 기존 음극활물질로 사용되는 탄소보다 단위 무게당 용량이 월등히 높은 고용량의 비탄소계 음극활물질이 활발하게 연구되고 있다. 이 중 규소계 음극활물질은 낮은 가격과 높은 용량, 예컨대 상용의 음극활물질인 흑연 대비 약 10배의 방전용량(약 4200mAh/g)을 가지는 고용량 음극활물질로 알려지고 있다.Meanwhile, as high-capacity batteries continue to be required due to the development of portable electronic devices, high-capacity non-carbon-based negative electrode active materials having a much higher capacity per unit weight than carbon used as conventional negative electrode active materials have been actively studied. Among these, the silicon-based negative electrode active material is known as a high capacity negative electrode active material having a low price and high capacity, for example, a discharge capacity (about 4200 mAh / g) of about 10 times that of graphite, which is a commercial negative electrode active material.
하지만, 상기 규소계 음극활물질은 부도체인 점과 충방전 과정 동안 진행되는 급격한 부피 변화로 인하여, 수반되는 여러 부 반응, 예컨대 음극활물질 입자의 분쇄가 발생하거나, 불안정한 SEI(Solid Electrolyte Interface)층을 형성하거나, 또는 전기 접촉에 의해 용량이 감소하는 등 전지 성능 저하가 일어나, 상용화에 큰 제약을 받고 있다.However, the silicon-based negative electrode active material is a nonconductor, and due to the rapid volume change that occurs during the charging and discharging process, the accompanying side reactions, for example, pulverization of the negative electrode active material particles, or form an unstable solid electrolyte interface (SEI) layer. In addition, battery performance is deteriorated, such as a decrease in capacity due to electrical contact, and there is a significant limitation in commercialization.
최근 충방전에 따른 규소계 음극활물질의 분쇄를 최소화하기 위하여, 나노 크기의 규소계 음극활물질을 제조하는 기술이 제안되고 있다.Recently, in order to minimize the pulverization of the silicon-based negative electrode active material due to charging and discharging, a technique for preparing a silicon-based negative electrode active material of nano size has been proposed.
하지만, 나노 크기의 규소계 음극활물질을 제조하기 위해서는 규소계 물질 덩어리를 만든 후, 나노 크기로 분쇄하는 과정을 거쳐야 하는데, 이때 나노 크기의 규소계 입자의 결정성을 제어하기가 쉽지 않다는 단점이 있다. 또한, 상기 분쇄 과정에서 규소계 음극활물질이 산화되면서, 결론적으로 이차전지의 초기 효율이 감소하는 문제점이 있다.However, in order to manufacture nano-sized silicon-based anode active material, a silicon-based material mass must be made and then crushed to nano-sized, but there is a disadvantage that it is difficult to control the crystallinity of nano-sized silicon-based particles. . In addition, as the silicon-based negative active material is oxidized in the crushing process, there is a problem in that the initial efficiency of the secondary battery is reduced.
따라서, 이러한 문제점을 해결하기 위하여, 나노 크기의 규소계 음극활물질 제조 시에 산화를 방지할 수 있는 방법의 개발이 요구되고 있다.Therefore, in order to solve this problem, the development of a method capable of preventing oxidation in the production of nano-sized silicon-based anode active material is required.
선행기술문헌Prior art literature
대한민국 공개특허공보 제10-2015-0109056호Republic of Korea Patent Publication No. 10-2015-0109056
대한민국 공개특허공보 제10-2014-0094676호Republic of Korea Patent Publication No. 10-2014-0094676
상기와 같은 문제를 해결하기 위하여 안출된 것으로, 본 발명의 제1 기술적 과제는 나노 크기의 규소 입자 제조 시에 산화를 방지할 수 있는 이차전지용 음극활물질의 제조방법을 제공하는 것을 목적으로 한다.In order to solve the above problems, the first technical problem of the present invention is to provide a method for producing a negative electrode active material for secondary batteries that can prevent oxidation during the production of nano-sized silicon particles.
본 발명의 제2 기술적 과제는 상기 음극활물질의 제조 방법에 의해 제조된 이차전지용 음극활물질을 제공하는 것을 목적으로 한다.A second object of the present invention is to provide a negative electrode active material for a secondary battery manufactured by the method for producing a negative electrode active material.
본 발명의 제3 기술적 과제는 본 발명의 음극활물질을 포함하는 이차전지용 음극을 제공하는 것을 목적으로 한다.A third object of the present invention is to provide a negative electrode for a secondary battery including the negative electrode active material of the present invention.
또한, 본 발명의 제4 기술적 과제는 본 발명의 음극을 구비함으로써, 방전 용량, 초기 효율 및 출력 특성이 개선된 리튬 이차전지를 제공하는 것을 목적으로 한다.In addition, a fourth technical object of the present invention is to provide a lithium secondary battery having improved discharge capacity, initial efficiency and output characteristics by providing the negative electrode of the present invention.
상기 과제를 해결하기 위하여, 본 발명의 일 실시예에서는In order to solve the above problems, in one embodiment of the present invention
실란(SiH4) 가스를 소스로 사용하는 화학기상증착법(CVD)으로 유기 기판 표면에 비정질 규소층을 증착하는 단계(S1);Depositing an amorphous silicon layer on the surface of the organic substrate by chemical vapor deposition (CVD) using a silane (SiH 4 ) gas as a source (S1);
상기 비정질 규소층을 초음파 분쇄하여 비정질 규소입자를 제조하는 단계(S2);Ultrasonically grinding the amorphous silicon layer to prepare amorphous silicon particles (S2);
상기 비정질 규소입자를 탄소계 전구체 용액에 분산시켜 분산 용액을 제조하는 단계(S3); Dispersing the amorphous silicon particles in a carbon-based precursor solution to prepare a dispersion solution (S3);
상기 분산 용액을 분무 건조하여 규소계 복합 전구체를 제조하는 단계(S4); 및Spray drying the dispersion solution to prepare a silicon-based composite precursor (S4); And
상기 규소계 복합 전구체를 열처리하여, 내부에 1 이상의 비정질 규소입자를 포함하는 비정질 탄소 코팅층을 포함하는 규소계 복합체를 형성하는 단계(S5);를 포함하는 리튬 이차전지용 음극활물질의 제조 방법을 제공한다.The heat treatment of the silicon-based composite precursor, to form a silicon-based composite comprising an amorphous carbon coating layer containing one or more amorphous silicon particles therein (S5); provides a method for producing a negative electrode active material for a lithium secondary battery comprising a. .
상기 비정질 규소층 증착 단계(S1)는 500℃ 내지 700℃의 온도 및 10-8 Torr 내지 760 Torr (1 기압), 구체적으로 10-2 Torr 내지 760 Torr의 압력 조건하에서 실란 가스를 10 sccm/60min 내지 50 sccm/60min의 속도로 가하면서 실시할 수 있다.The amorphous silicon layer deposition step (S1) is 10 sccm / 60min silane gas at a temperature of 500 ℃ to 700 ℃ and 10 -8 Torr to 760 Torr (1 atmosphere), specifically 10 -2 Torr to 760 Torr It can be carried out while adding at a rate of from 50 sccm / 60 min.
이때, 상기 증착된 비정질 규소층의 두께는 20nm 내지 500nm 이다.At this time, the thickness of the deposited amorphous silicon layer is 20nm to 500nm.
또한, 상기 비정질 규소층 분쇄 단계(S2)는 아세톤 용액에 비정질 규소층이 증착된 유리 기판을 침지한 다음, 초음파 분쇄기를 이용하여 50W 내지 200W 사이의 출력으로 상온에서 10분 내지 20분 동안 분쇄를 실시할 수 있다.In addition, the amorphous silicon layer crushing step (S2) is immersed in the acetone solution a glass substrate on which an amorphous silicon layer is deposited, and then pulverized for 10 minutes to 20 minutes at room temperature with an output between 50W and 200W using an ultrasonic grinder. It can be carried out.
본 발명의 방법은 상기 비정질 규소 입자를 제조한 다음, 아세톤 용매를 휘발시켜 분쇄된 비정질 규소입자를 포집하는 단계를 추가로 포함할 수 있다.The method of the present invention may further include preparing the amorphous silicon particles, and then collecting the pulverized amorphous silicon particles by volatilizing an acetone solvent.
상기 분쇄된 비정질 규소입자의 평균입경(D50)은 5nm 내지 500nm이다.The average particle diameter (D50) of the pulverized amorphous silicon particles is 5nm to 500nm.
또한, 상기 분산 용액 제조 단계(S3)는 증류수에, 1000℃ 이하의 온도에서 탄화 가능한 탄소계 물질을 혼합하여 탄소계 전구체 용액을 제조한 다음, 비정질 규소 입자를 분산시켜 실시할 수 있다. In addition, the dispersion solution manufacturing step (S3) may be carried out by mixing carbonizable carbon-based materials in distilled water at a temperature of 1000 ° C. or less to prepare a carbon-based precursor solution, and then dispersing amorphous silicon particles.
상기 탄소계 전구체 용액은 비정질 규소 입자 100 중량부에 대하여 25 중량부 내지 4,000 중량부를 사용할 수 있다.The carbon-based precursor solution may be used from 25 parts by weight to 4,000 parts by weight based on 100 parts by weight of amorphous silicon particles.
또한, 상기 본 발명의 방법에서는 상기 비정질 규소입자 분산 시에, 결정질 및 비정질 탄소로 이루어진 군으로부터 선택된 적어도 하나 이상의 전도성 탄소계 물질을 함께 분산할 수 있다.In the method of the present invention, at the time of dispersing the amorphous silicon particles, at least one conductive carbon-based material selected from the group consisting of crystalline and amorphous carbon may be dispersed together.
상기 전도성 탄소계 물질은 비정질 규소 입자 100 중량부에 대하여 0.99 중량부 내지 1900 중량부가 사용될 수 있다. The conductive carbonaceous material may be used in an amount of 0.99 parts by weight to 1900 parts by weight based on 100 parts by weight of amorphous silicon particles.
또한, 상기 분산 용액을 분무 건조하는 단계(S4)는 상기 전구체 용액을 분무 장치 내로 공급하여 분무에 의해 액적을 형성한 후, 상기 액적을 건조하는 단계가 동시에 수행될 수 있다.In the spray drying step (S4), the precursor solution may be supplied into a spray device to form a droplet by spraying, and then the drying of the droplet may be simultaneously performed.
이때, 상기 분무 건조 단계는 약 50℃ 내지 300℃에서 10 mL/min 내지 50 mL/min의 속도로 실시할 수 있다.At this time, the spray drying step may be carried out at a rate of 10 mL / min to 50 mL / min at about 50 ℃ to 300 ℃.
또한, 상기 규소계 복합 전구체를 열처리하는 단계(S5)는 400℃ 내지 1000℃ 온도에서, 약 10분 내지 1시간 동안 실시할 수 있다.In addition, the step (S5) of the heat treatment of the silicon-based composite precursor may be performed at 400 ℃ to 1000 ℃ temperature, for about 10 minutes to 1 hour.
또한, 본 발명의 일 실시예에서는In addition, in one embodiment of the present invention
본 발명의 방법에 의해 제조된 리튬 이차전지용 음극활물질로서,As a negative electrode active material for a lithium secondary battery produced by the method of the present invention,
비정질 탄소 코팅층; 및 상기 비정질 탄소 코팅층 내부에 포함된 1 이상의 비정질 규소입자로 이루어진 규소 복합체를 포함하는 리튬 이차전지용 음극활물질을 제공한다.Amorphous carbon coating layer; And it provides a negative electrode active material for a lithium secondary battery comprising a silicon composite consisting of one or more amorphous silicon particles contained in the amorphous carbon coating layer.
상기 비정질 규소입자는 단일 입자 또는 상기 단일 입자로 이루어진 1차 비정질 규소입자가 응집되어 형성된 2차 비정질 규소입자를 포함할 수 있다. 상기 비정질 규소입자는 비정질 탄소 코팅층 내부에 균일하게 분산되어 있을 수 있다.The amorphous silicon particles may include single amorphous particles or secondary amorphous silicon particles formed by aggregation of primary amorphous silicon particles formed of the single particles. The amorphous silicon particles may be uniformly dispersed in the amorphous carbon coating layer.
상기 비정질 규소입자는 음극활물질 전체 중량에 대하여 1 내지 95 중량%로 포함될 수 있고, 구체적으로는 5 내지 90 중량%로 포함될 수 있다.The amorphous silicon particles may be included in an amount of 1 to 95% by weight, and specifically 5 to 90% by weight, based on the total weight of the negative electrode active material.
상기 비정질 규소입자 : 비정질 탄소 코팅층의 중량비는 1:99 내지 95:5, 구체적으로 5:95 내지 90:10일 수 있다.The weight ratio of the amorphous silicon particles to the amorphous carbon coating layer may be 1:99 to 95: 5, specifically 5:95 to 90:10.
상기 음극활물질은 비정질 탄소 코팅층 내부에 결정질 또는 상기 비정질 탄소층 형성 물질과 상이한 비정질 탄소로 이루어진 군으로부터 선택된 적어도 하나 이상의 전도성 탄소계 물질을 추가로 포함할 수 있다.The anode active material may further include at least one conductive carbon-based material selected from the group consisting of crystalline or amorphous carbon different from the amorphous carbon layer forming material in the amorphous carbon coating layer.
구체적으로, 상기 음극활물질은 비정질 탄소 코팅층; 및 상기 비정질 탄소 코팅층 내부에 포함된 1 이상의 비정질 규소입자 및 비정질 탄소로 이루어진 규소 복합체를 포함할 수 있다.Specifically, the negative electrode active material is an amorphous carbon coating layer; And it may include a silicon composite consisting of one or more amorphous silicon particles and amorphous carbon contained in the amorphous carbon coating layer.
또, 상기 음극활물질은 비정질 탄소 코팅층; 및 상기 비정질 탄소 코팅층 내부에 포함된 1 이상의 비정질 규소입자 및 결정질 탄소로 이루어져 있으며, 상기 1 이상의 비정질 규소 입자가 결정질 탄소 표면에 분포되어 있는 규소 복합체를 포함할 수 있다.In addition, the negative electrode active material is an amorphous carbon coating layer; And one or more amorphous silicon particles and crystalline carbon contained in the amorphous carbon coating layer, and the silicon composite may include the one or more amorphous silicon particles distributed on the surface of the crystalline carbon.
상기 전도성 탄소계 물질은 음극활물질 전체 중량을 기준으로 0.1 중량% 내지 90 중량%로 포함될 수 있다. 구체적으로, 상기 전도성 탄소계 물질이 비정질 탄소인 경우 음극활물질 전체 중량을 기준으로 0.1 중량% 내지 50 중량%로 포함될 수 있고, 상기 전도성 탄소계 물질이 결정질 탄소인 경우, 음극활물질 전체 중량을 기준으로 10 중량% 내지 90 중량%로 포함될 수 있다. The conductive carbon-based material may be included in an amount of 0.1 wt% to 90 wt% based on the total weight of the negative electrode active material. Specifically, when the conductive carbon-based material is amorphous carbon, it may be included in an amount of 0.1% to 50% by weight based on the total weight of the negative electrode active material, and when the conductive carbon-based material is crystalline carbon, based on the total weight of the negative electrode active material 10 wt% to 90 wt% may be included.
또 다른, 본 발명의 일 실시예에서는In another embodiment of the present invention,
집전체, 및 상기 집전체의 적어도 일면에 형성된 본 발명의 방법에 의해 제조된 음극 활물질을 포함하는 음극을 제공한다Provided is a negative electrode comprising a current collector and a negative electrode active material produced by the method of the present invention formed on at least one surface of the current collector.
또한, 본 발명의 일 실시예에서는 상기 음극을 구비한 리튬 이차전지를 제공한다.In addition, an embodiment of the present invention provides a lithium secondary battery having the negative electrode.
본 발명의 방법에 따르면, 나노 규소 입자 제조 시에 산화가 방지되고, 결정성이 제어된 음극활물질용 비정질 규소입자를 제조할 수 있다. 또한, 이러한 비정질 규소입자를 포함함으로써, 결정질 규소입자를 사용할 때 보다 전극 두께 팽창 현상이 감소된 음극활물질 및 이를 포함하는 음극을 제조할 수 있다. 나아가, 상기 음극을 구비함으로써 초기 효율 및 가역용량과 수명 특성이 향상된 리튬 이차전지를 제조할 수 있다. According to the method of the present invention, it is possible to produce amorphous silicon particles for the negative electrode active material in which oxidation is prevented and crystallinity is controlled during the production of the nano silicon particles. In addition, by including such amorphous silicon particles, it is possible to manufacture a negative electrode active material and a negative electrode including the same, the electrode thickness expansion phenomenon is reduced than when using the crystalline silicon particles. Furthermore, by providing the negative electrode, a lithium secondary battery having improved initial efficiency, reversible capacity, and lifetime characteristics can be manufactured.
본 명세서에 첨부되는 다음의 도면들은 본 발명의 바람직한 실시예를 예시하는 것이며, 전술한 발명의 내용과 함께 본 발명의 기술사상을 더욱 이해시키는 역할을 하는 것이므로, 본 발명은 그러한 도면에 기재된 사항에만 한정되어 해석되어서는 아니 된다.The following drawings, which are attached to this specification, illustrate preferred embodiments of the present invention, and together with the contents of the present invention serve to further understand the technical spirit of the present invention, the present invention is limited to the matters described in such drawings. It should not be construed as limited.
도 1은 본 발명의 실시예 1에서 제조된 규소 복합체를 포함하는 리튬 이차전지용 음극활물질의 모식도이다.1 is a schematic diagram of a negative electrode active material for a lithium secondary battery including the silicon composite prepared in Example 1 of the present invention.
도 2는 본 발명의 실시예 2에서 제조된 규소 복합체를 포함하는 리튬 이차전지용 음극활물질의 모식도이다.2 is a schematic view of a negative electrode active material for a lithium secondary battery including the silicon composite prepared in Example 2 of the present invention.
도 3은 본 발명의 실시예 3에서 제조된 규소 복합체를 포함하는 리튬 이차전지용 음극활물질의 모식도이다.3 is a schematic diagram of a negative electrode active material for a lithium secondary battery including the silicon composite prepared in Example 3 of the present invention.
부호의 설명Explanation of the sign
1, 11, 111: 비정질 규소입자1, 11, 111: amorphous silicon particles
13: 비정질 탄소13: amorphous carbon
5, 15, 115: 비정질 탄소 코팅층5, 15, 115: amorphous carbon coating layer
10, 50, 100: 음극활물질10, 50, 100: negative electrode active material
117: 결정질 탄소117: crystalline carbon
이하, 본 발명에 대한 이해를 돕기 위해 본 발명을 더욱 상세하게 설명한다.Hereinafter, the present invention will be described in more detail to aid in understanding the present invention.
본 명세서 및 청구범위에 사용된 용어나 단어는 통상적이거나 사전적인 의미로 한정해서 해석되어서는 아니 되며, 발명자는 그 자신의 발명을 가장 최선의 방법으로 설명하기 위해 용어의 개념을 적절하게 정의할 수 있다는 원칙에 입각하여 본 발명의 기술적 사상에 부합하는 의미와 개념으로 해석되어야만 한다.The terms or words used in this specification and claims are not to be construed as limiting in their usual or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best explain their invention in the best way possible. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.
최근 리튬 이차전지용 음극활물질로 규소계 음극활물질이 제안되고 있으나, 상기 규소계 음극활물질은 부도체인 점과 충방전 과정 동안 진행되는 급격한 부피 변화로 인하여, 음극활물질 입자의 분쇄가 발생하거나, 또는 불안정한 SEI(Solid Electrolyte Interface)층을 형성하여 전지 성능이 저하되는 단점이 있다. 특히, 실리콘에 높은 전기 전도성을 부여하기 위하여 개발된 Si/C 복합체의 경우, 부서지기 쉬운 성질의 탄소가 충방전 중 발생하는 실리콘의 부피팽창으로 파쇄되는 문제점을 가진다. 이를 개선하기 위하여, 나노 크기의 규소계 분말을 제조하기 위한 방법이 개발되고는 있으나, 분쇄 과정 중에 규소계 물질이 산화되면서, 초기 효율이 감소되는 또 다른 문제점이 발생할 수 있다.Recently, a silicon-based negative electrode active material has been proposed as a negative electrode active material for a lithium secondary battery, but the silicon-based negative electrode active material is a nonconductor, and due to the rapid volume change that occurs during the charging and discharging process, crushing of the negative electrode active material particles occurs or an unstable SEI. (Solid Electrolyte Interface) has a disadvantage in that the battery performance is reduced by forming a layer. In particular, in the case of Si / C composites developed to impart high electrical conductivity to silicon, the brittle carbon has a problem of being broken by volume expansion of silicon generated during charge and discharge. In order to improve this, a method for preparing a nano-sized silicon-based powder has been developed, but as the silicon-based material is oxidized during the grinding process, another problem may occur that the initial efficiency is reduced.
이에, 본 발명에서는 비정질 규소층을 증착한 다음, 초음파 분쇄를 실시함으로써, 결정성 제어가 용이하고, 제조 과정 중에 산화를 방지할 수 있는 비정질 규소입자를 제조할 수 있는 음극활물질 제조 방법을 제공할 수 있다. 또한, 이를 음극활물질로 사용함으로써, 초기 효율, 수명 특성 및 전극 두께 팽창 특성이 향상된 리튬 이차전지를 제조할 수 있다.Thus, in the present invention, by depositing an amorphous silicon layer, and then performing an ultrasonic grinding, it is possible to provide a method for producing a negative electrode active material that can be used to prepare amorphous silicon particles that can easily control the crystallinity and prevent oxidation during the manufacturing process. Can be. In addition, by using this as a negative electrode active material, it is possible to manufacture a lithium secondary battery with improved initial efficiency, life characteristics and electrode thickness expansion characteristics.
구체적으로, 본 발명은 일 실시예에서는Specifically, the present invention in one embodiment
실란(SiH4) 가스를 소스로 사용하는 화학기상증착법(CVD)으로 유기 기판 표면에 비정질 규소층을 증착하는 단계(S1);Depositing an amorphous silicon layer on the surface of the organic substrate by chemical vapor deposition (CVD) using a silane (SiH 4 ) gas as a source (S1);
상기 비정질 규소층을 초음파 분쇄하여 비정질 규소입자를 제조하는 단계(S2);Ultrasonically grinding the amorphous silicon layer to prepare amorphous silicon particles (S2);
상기 비정질 규소입자를 탄소계 전구체 용액에 분산시켜 분산 용액을 제조하는 단계(S3); Dispersing the amorphous silicon particles in a carbon-based precursor solution to prepare a dispersion solution (S3);
상기 분산 용액을 분무 건조하여 규소계 복합 전구체를 제조하는 단계(S4); 및Spray drying the dispersion solution to prepare a silicon-based composite precursor (S4); And
상기 규소계 복합 전구체를 열처리하여, 내부에 1 이상의 비정질 규소입자를 포함하는 비정질 탄소 코팅층을 포함하는 규소 복합체를 형성하는 단계(S5);를 포함하는 리튬 이차전지용 음극활물질의 제조 방법을 제공한다.The heat treatment of the silicon-based composite precursor, to form a silicon composite comprising an amorphous carbon coating layer including one or more amorphous silicon particles therein (S5); provides a method for producing a negative electrode active material for a lithium secondary battery comprising a.
이때, 본 발명의 방법에 있어서, 상기 비정질 규소층 증착 단계(S1)는 700℃ 이하, 구체적으로 500℃ 내지 700℃의 온도 및 10-8 Torr 내지 760Torr (1 기압), 구체적으로 10-2 Torr 내지 760 Torr의 압력 조건하에서 실란 가스를 10 sccm/60min 내지 50 sccm/60min의 속도로 가하면서 실시할 수 있다. At this time, in the method of the present invention, the amorphous silicon layer deposition step (S1) is 700 ℃ or less, specifically 500 ℃ to 700 ℃ temperature and 10 -8 Torr to 760 Torr (1 atm), specifically 10 -2 Torr The silane gas may be carried out at a rate of 10 sccm / 60 min to 50 sccm / 60 min under a pressure condition of 760 Torr.
상술한 바와 같이, 본 발명의 방법에서는 500℃ 내지 700℃ 온도 범위에서 화학기상증착법을 실시함으로써, 규소 원소간의 결합력이 약하여, 후술하는 초음파 분쇄 단계에서 쉽게 분쇄할 수 있을 정도로 깨지기 쉬운(brittle) 얇은 두께의 비정질 규소층을 증착할 수 있다. 만약, 상기 실란 가스를 500℃ 미만의 온도에서 가하는 경우, 비정질 규소층이 증착되지 않을 수도 있다. 반면에, 실란 가스를 700℃ 초과 온도에서 가하는 경우, 규소계 입자의 결정 성장이 증가되어, 결정성 규소층이 형성될 수 있다.As described above, in the method of the present invention, by performing the chemical vapor deposition method in the temperature range of 500 ° C to 700 ° C, the bonding force between the silicon elements is weak, and thin enough to be easily broken in the ultrasonic grinding step described later. A thick amorphous silicon layer can be deposited. If the silane gas is added at a temperature below 500 ° C., an amorphous silicon layer may not be deposited. On the other hand, when silane gas is added at a temperature above 700 ° C., crystal growth of silicon-based particles may be increased to form a crystalline silicon layer.
이와 같이, 본 발명의 방법에서는 낮은 온도 범위에서 화학적 기상 증착 방법을 실시함으로써, 규소 입자의 결정 성장을 억제하여, 비정질 규소층을 형성할 수 있다. 이러한 본 발명의 화학기상증착법에 의해 형성된 비정질 규소층의 경우, 나노 입자로 제조하는 경우 결정질 규소층에 비하여 수명 특성이 우수하고, 부피 팽창이 작다는 이점이 있다.As described above, in the method of the present invention, by performing a chemical vapor deposition method in a low temperature range, crystal growth of silicon particles can be suppressed to form an amorphous silicon layer. In the case of the amorphous silicon layer formed by the chemical vapor deposition method of the present invention, the nanoparticles have an advantage of excellent life characteristics and small volume expansion compared to the crystalline silicon layer.
상기 비정질 규소층은 약 20nm 내지 500nm 두께로 증착될 수 있다.The amorphous silicon layer may be deposited to a thickness of about 20nm to 500nm.
만약, 상기 비정질 규소층의 증착 두께가 20nm 미만인 경우, 후속 초음파 분쇄 공정을 실시할 때, 포집된 규소입자의 입경이 매우 작고, 비표면적이 증가하여 초기 효율이 감소할 수 있다. 반면에, 상기 비정질 규소층의 증착 두께가 500nm를 초과하는 경우 후속 초음파 분쇄 공정을 안정적인 진행하기 어려울 수 있다.If the deposition thickness of the amorphous silicon layer is less than 20 nm, when the subsequent ultrasonic grinding process is performed, the particle size of the collected silicon particles is very small, and the specific surface area is increased, thereby decreasing initial efficiency. On the other hand, when the deposition thickness of the amorphous silicon layer exceeds 500nm, it may be difficult to proceed with the subsequent ultrasonic grinding process stable.
또한, 본 발명의 방법에 있어서, 상기 비정질 규소층 분쇄 단계(S2)는 상기 비정질 규소층이 증착된 유리 기판을 아세톤이 담긴 비이커에 함침한 후, 초음파 분쇄기를 이용하여 50 W 내지 200 W의 출력으로 상온에서 10 내지 20분 동안 초음파 분쇄를 실시할 수 있다. 이때, 상기 이외의 초음파 출력이나 처리 시간이라도 원하는 크기의 나노 입자 크기의 비정질 규소 입자로 분쇄할 수 있는 경우, 충분히 사용할 수 있다.In addition, in the method of the present invention, the amorphous silicon layer grinding step (S2) is impregnated in the beaker containing acetone, the glass substrate on which the amorphous silicon layer is deposited, and then outputs 50 W to 200 W using an ultrasonic grinder. Ultrasonic grinding may be performed at room temperature for 10 to 20 minutes. At this time, even if it is possible to grind | pulverize amorphous silicon particle of the nanoparticle size of a desired size even if it is an ultrasonic output other than the above and processing time, it can use sufficiently.
상기 아세톤의 사용량은 규소층의 두께 비율과 크게 상관 없으나, 비정질 규소층이 증착된 유리 기판이 아세톤에 완전히 함침될 정도로 사용될 수 있다.The amount of acetone used may be largely independent of the thickness ratio of the silicon layer, but may be used to the extent that the glass substrate on which the amorphous silicon layer is deposited is completely impregnated with acetone.
한편, 본 발명의 방법에 의해 제조된 결정성이 매우 낮은, 비정질 규소 입자의 경우, 분쇄 후 건조 과정에서 높은 온도로 열을 가해 줄 경우, 분쇄된 비정질 규소 입자의 결정성이 증가하여 결정질 규소 입자가 형성될 수 있다. 따라서, 건조 공정은 최대한 낮은 온도에서 진행해야 하며, 이를 위하여, 초음파 분쇄 공정 시에 아세톤과 같이 낮은 온도에서도 휘발성이 강한 용매를 사용하는 것이 바람직하다. 이때, 상기 아세톤 외에 에탄올 또는 메탄올과 같이 낮은 온도에서도 휘발성이 강한 유기 용매를 사용할 수도 있다.On the other hand, in the case of amorphous silicon particles having a very low crystallinity produced by the method of the present invention, when heat is applied at a high temperature in the drying process after grinding, the crystallinity of the crushed amorphous silicon particles increases to increase the crystalline silicon particles Can be formed. Therefore, the drying process should proceed at the lowest possible temperature, for this purpose, it is preferable to use a solvent that is highly volatile even at low temperatures such as acetone during the ultrasonic grinding process. In this case, in addition to the acetone, an organic solvent having high volatility may be used even at a low temperature such as ethanol or methanol.
종래 일반적인 기계적 분쇄 공정은 공정 시간이 길고, 분쇄 과정 중 입자 간의 마찰에 의해 온도가 증가할 수 있으며, 이로 인해 주변의 산소 또는 수분과 규소 입자가 반응하여 규소입자의 산화가 발생할 수 있다. 하지만, 본 발명과 같은 방법의 경우, 비정질 규소층을 증착한 다음, 초음파 분쇄를 실시함으로써, 낮은 온도에서 짧은 시간 안에 비정질 규소층을 분쇄할 수 있을 뿐만 아니라, 이와 동시에 초음파 분쇄된 비정질 규소 입자를 포집하는 공정을 진행하기 때문에, 분쇄 과정 중 규소의 결정립이 성장하거나, 규소입자가 산화되는 문제점을 방지할 수 있다. In the conventional general mechanical grinding process, the processing time is long, and the temperature may increase due to the friction between the particles during the grinding process. As a result, the oxidation of the silicon particles may occur due to the reaction of surrounding oxygen or moisture with silicon particles. However, in the method of the present invention, by depositing an amorphous silicon layer and then performing an ultrasonic grinding, not only can the amorphous silicon layer be ground in a short time at low temperature, but also the ultrasonically pulverized amorphous silicon particles Since the process of collecting is carried out, it is possible to prevent the problem that silicon grains grow or silicon particles are oxidized during the grinding process.
또한, 본 발명의 방법에서는 상기 초음파 분쇄 공정 완료 후, 아세톤 용매를 휘발시켜 분쇄된 비정질 규소입자를 포집하는 단계를 포함할 수 있다.In addition, the method of the present invention may include the step of collecting the pulverized amorphous silicon particles by volatilizing acetone solvent after the completion of the ultrasonic grinding process.
상기 본 발명의 방법에 의해 수득된 상기 비정질 규소 입자의 평균입경(D50)은 5nm 내지 500nm, 구체적으로 20nm 내지 200nm일 수 있다.The average particle diameter (D50) of the amorphous silicon particles obtained by the method of the present invention may be 5nm to 500nm, specifically 20nm to 200nm.
만약, 상기 비정질 규소입자의 평균입경이 5nm 미만인 경우 비표면적이 너무 커져 가역용량의 손실이 발생할 수 있고, 500nm를 초과하면 입자 크기가 커서 리튬 이온과 반응 시 부피 팽창이 심해지기 때문에, 전체 구상의 음극활물질의 부피팽창을 완충시키는 효율성이 떨어지게 된다.If the average particle diameter of the amorphous silicon particles is less than 5 nm, the specific surface area may be too large, resulting in loss of reversible capacity. If the average particle diameter is larger than 500 nm, the particle size is large and the volume expansion becomes severe when reacting with lithium ions. The efficiency of buffering the volume expansion of the negative electrode active material is inferior.
즉, 일반적으로 음극 활물질은 충전시 전해액과 반응하여 입자 표면에 SEI 막이라는 보호막을 형성하는데, 이론적으로 SEI 막은 한번 생성되면 잘 분해되지 않는다. 하지만, 음극활물질의 부피 변화나 크랙에 의해, 또는 외부에서 가해진 열 또는 충격에 의해 SEI 막이 깨질 수도 있고, 이러한 경우 전극 표면이 전해액에 노출되면, SEI 막이 재 생성되기도 한다. 만약, 상기 단일 규소 입자의 평균입경(D50)이 500nm를 초과하는 경우, 충방전으로 인해 크랙이 반복적으로 발생하기 때문에, 반복적으로 SEI 막이 생성되면서 부피가 증가하게 된다. 이와 같이, 규소 입자의 부피 증가는 곧 최종 음극활물질 입자의 부피 증가를 야기하게 된다.That is, in general, the negative electrode active material reacts with the electrolyte during filling to form a protective film called an SEI film on the surface of the particle. In theory, the SEI film does not decompose well once produced. However, the SEI film may be broken by the volume change or crack of the negative electrode active material, or by heat or impact applied externally. In this case, when the electrode surface is exposed to the electrolyte, the SEI film may be regenerated. If the average particle diameter (D50) of the single silicon particles exceeds 500 nm, since cracks are repeatedly generated due to charge and discharge, the volume increases as the SEI film is repeatedly generated. As such, an increase in the volume of the silicon particles will soon lead to an increase in the volume of the final anode active material particles.
또한, 본 발명의 방법에 있어서, 상기 분산 용액 제조 단계(S3)에서는 증류수에, 1000℃ 이하의 온도에서 탄화 가능한 탄소계 물질을 혼합하여 탄소계 전구체 용액을 제조한 다음, 비정질 규소 입자를 분산시키는 단계로 실시할 수 있다. In addition, in the method of the present invention, in the dispersion solution preparation step (S3) to prepare a carbon-based precursor solution by mixing a carbonaceous carbon material at a temperature of 1000 ℃ or less in distilled water, and then to disperse amorphous silicon particles Can be carried out in stages.
상기 증류수 : 탄소계 물질을 대략 1:2 내지 10:1의 중량비로 혼합하여 제조할 수 있다.It can be prepared by mixing the distilled water: carbon-based material in a weight ratio of approximately 1: 2 to 10: 1.
상기 1000℃ 이하의 낮은 온도에서도 탄화가 가능한 탄소계 물질은 그 대표적인 예로 수크로오스, 글루코오스, 프룩토오스, 갈락토오스, 말토오스, 및 락토오스로 이루어진 군으로부터 선택된 단일물 또는 2종 이상의 혼합물을 들 수 있으며, 이 중에서도 상대적으로 낮은 온도에서 탄화가 가능한 수크로오스를 들 수 있다.The carbonaceous material which can be carbonized even at a low temperature of 1000 ° C. or lower may include a single substance or a mixture of two or more selected from the group consisting of sucrose, glucose, fructose, galactose, maltose, and lactose. Sucrose may be carbonized at a relatively low temperature.
본 발명의 방법에 있어서, 상기 탄소계 전구체 용액은 비정질 규소 입자 100 중량부에 대하여 25 중량부 내지 4,000 중량부를 사용할 수 있다. 만약, 상기 탄소계 전구체 용액이 사용량이 25 중량부 미만인 경우, 비정질 규소 입자/탄소계 전구체 용액의 점도가 높아 분무 공정을 실시하기 쉽지 않고, 탄소계 전구체 용액의 사용량이 4,000 중량부를 초과하는 경우, 분산 용액 중의 비정질 규소 입자의 함량이 매우 낮아 고용량 음극재로서의 역할이 감소할 수 있다.In the method of the present invention, the carbon-based precursor solution may be used from 25 parts by weight to 4,000 parts by weight based on 100 parts by weight of amorphous silicon particles. If the amount of the carbon-based precursor solution is less than 25 parts by weight, the viscosity of the amorphous silicon particles / carbon-based precursor solution is not easy to perform a spray process, when the amount of the carbon-based precursor solution exceeds 4,000 parts by weight, The content of amorphous silicon particles in the dispersion solution is so low that the role as a high capacity negative electrode material can be reduced.
또한, 상기 본 발명의 방법에서는 상기 비정질 규소입자를 분산하여 분산 용액을 제조할 때, 결정질 탄소 및 비정질 탄소로 이루어진 군으로부터 선택된 적어도 하나 이상의 전도성 탄소계 물질을 함께 분산할 수 있다. 이때, 상기 비정질 탄소는 전술한 바와 같은 비정질 탄소층 형성 물질과 상이한 물질인 것이 바람직하다.In addition, in the method of the present invention, when preparing the dispersion solution by dispersing the amorphous silicon particles, at least one conductive carbon-based material selected from the group consisting of crystalline carbon and amorphous carbon may be dispersed together. In this case, the amorphous carbon is preferably a material different from the amorphous carbon layer forming material as described above.
즉, 본 발명의 음극활물질은 규소 입자의 낮은 도전성을 보완해주거나, 2차 입자화 했을 때 구조 지지체의 역할을 구현하기 위하여, 전도성 탄소계 물질을 더 포함할 수 있다.That is, the negative electrode active material of the present invention may further include a conductive carbon-based material to supplement the low conductivity of the silicon particles or to implement the role of the structural support when secondary particles are formed.
상기 전도성 탄소계 물질은 비정질 규소 입자 100 중량부에 대하여 0.99 중량부 내지 1,900 중량부가 분산될 수 있다. The conductive carbonaceous material may be dispersed in a range of 0.99 parts by weight to 1,900 parts by weight based on 100 parts by weight of amorphous silicon particles.
만약, 상기 전도성 탄소계 물질의 양이 0.99 중량부 미만인 경우, 도전성 개선이나 구조 지지체의 역할을 못하게 되고, 1,900 중량부를 초과하는 경우, 규소계 활물질 함량이 감소하여, 무게당 방전용량(mAh/g)이 감소하기 때문에, 최종 활물질의 방전용량 측면에서 이점이 없다. If the amount of the conductive carbonaceous material is less than 0.99 parts by weight, the conductivity does not improve or serve as a structural support, and if the amount exceeds 1,900 parts by weight, the silicon-based active material content is reduced, the discharge capacity per weight (mAh / g Since) decreases, there is no advantage in terms of discharge capacity of the final active material.
상기 전도성 탄소계 물질은 전지에 화학적 변화를 유발하지 않으면서 도전성을 가지는 결정질 또는 비정질 탄소라면 특별히 제한되지 않으며, 구체적으로 상기 결정질 탄소는 천연 흑연, 인조 흑연 또는 그래핀 등을 포함할 수 있고, 상기 비정질 탄소는 하드 카본, 소프트 카본, 카본블랙, 아세틸렌 블랙, 케첸 블랙, 채널 블랙, 퍼네이스 블랙, 램프 블랙, 서멀 블랙, 및 카본나노섬유로 이루어진 군으로부터 선택된 단일물 또는 2종 이상의 혼합물 등이 사용될 수 있다. The conductive carbon-based material is not particularly limited as long as it is a crystalline or amorphous carbon having conductivity without causing chemical change in the battery. Specifically, the crystalline carbon may include natural graphite, artificial graphite, graphene, or the like. As the amorphous carbon, a single material or a mixture of two or more selected from the group consisting of hard carbon, soft carbon, carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and carbon nanofibers may be used. have.
이때, 상기 결정질 탄소인 천연 흑연 또는 인조 흑연 입자의 평균입경(D50)은 300㎚ 내지 30㎛ 일 수 있다. 상기 천연 또는 인조 흑연 입자의 평균입경이 300㎚ 미만인 경우 구조 지지체로서의 역할이 감소할 수 있다는 단점이 있고, 30㎛ 를 초과하는 경우 최종 음극활물질의 평균입경이 증가하여 이차 전지 제조 시 코팅 공정을 어렵게 할 수 있다는 단점이 있다.In this case, the average particle diameter (D50) of the natural graphite or artificial graphite particles of the crystalline carbon may be 300nm to 30㎛. When the average particle diameter of the natural or artificial graphite particles is less than 300 nm, the role as a structural support may be reduced. When the average particle diameter of the natural or artificial graphite particles is greater than 30 μm, the average particle diameter of the final negative electrode active material is increased, making the coating process difficult in manufacturing a secondary battery. The disadvantage is that you can.
본 발명의 음극활물질은 상기 전도성 탄소계 물질 외에 선택적으로 금속 섬유, 금속 분말, 산화아연, 티탄산 칼륨, 산화티탄, 및 폴리페닐렌 유도체로 이루어진 군으로부터 선택된 단일물 또는 이들 중 2종 이상의 전도성 물질을 추가로 포함할 수 있다. In addition to the conductive carbonaceous material, the negative electrode active material of the present invention may optionally add a single material selected from the group consisting of metal fibers, metal powders, zinc oxide, potassium titanate, titanium oxide, and polyphenylene derivatives, or two or more of these conductive materials. It can be included as.
또한, 본 발명의 방법에서 있어서, 규소계 복합 전구체를 제조하기 위한 분무 건조 단계(S4)는 상기 전구체 용액을 분무 장치 내로 공급하여 분무에 의해 액적을 형성한 후, 상기 액적을 건조하는 단계가 동시에 수행될 수 있다.In addition, in the method of the present invention, the spray drying step (S4) for preparing a silicon-based composite precursor is supplied to the precursor solution into a spray device to form a droplet by spraying, and then the step of drying the droplet simultaneously Can be performed.
상기 분무 단계는 회전 분무, 노즐 분무, 초음파 분무 또는 이들의 조합을 포함하는 건조법을 이용하여 약 50℃ 내지 300℃, 구체적으로 80℃ 내지 250℃의 온도에서 10 mL/min 내지 50 mL/min의 속도로 실시할 수 있다. The spraying step may be carried out using a drying method including rotary spraying, nozzle spraying, ultrasonic spraying, or a combination thereof, from 10 mL / min to 50 mL / min at a temperature of about 50 ° C to 300 ° C, specifically 80 ° C to 250 ° C. Can be done at speed.
이때, 상기 온도 및 속도 범위 내에서 분무 건조될 경우 용매의 액정 상태 및 건조가 안정적으로 이루어진다.At this time, the liquid crystal state and drying of the solvent is stably made when the spray drying within the temperature and speed range.
한편, 본 발명에 포함되는 비정질 규소 입자의 평균입경(D50)은 5nm 내지 500nm이고, 비정질 탄소 입자의 평균입경(D50)은 약 100nm 내지 300nm이며, 결정질 탄소 입자의 평균입경(D50)은 300 nm 이상, 구체적으로 수㎛ 내지 30 ㎛ 이다. 따라서, 상기 분무 단계에서 비정질 규소 입자와 비정질 탄소 입자를 함께 분무하여 복합화하는 경우, 두 입자는 평균입경에 큰 차이가 없기 때문에 도 2에 나타낸 바와 같이 최종 활물질 내부에 비정질 규소 입자와 비정질 탄소 입자가 고르게 분포되는 형태로 제조된다. 반면에, 상기 분무 단계에서 비정질 규소 입자와 결정질 탄소 입자를 함께 분산하여 복합화하는 경우, 두 입자의 평균입경 차이에 의하여, 즉 결정질 탄소의 평균입경이 비정질 규소 입자의 평균입경 대비 크기 때문에, 도 3에 나타낸 바와 같이 결정질 탄소 입자 표면에 비정질 규소 입자가 코팅되는 듯한 형상으로 제조될 수 있다. Meanwhile, the average particle diameter (D50) of the amorphous silicon particles included in the present invention is 5 nm to 500 nm, the average particle diameter (D50) of the amorphous carbon particles is about 100 nm to 300 nm, and the average particle diameter (D50) of the crystalline carbon particles is 300 nm. The above is specifically several micrometers-30 micrometers. Therefore, in the spraying step, when the amorphous silicon particles and the amorphous carbon particles are sprayed together and complexed, the two particles do not have a large difference in average particle diameter, so that the amorphous silicon particles and the amorphous carbon particles are formed inside the final active material as shown in FIG. 2. It is produced in a form of even distribution. On the other hand, in the spraying step, when the amorphous silicon particles and the crystalline carbon particles are dispersed together in the composite, due to the difference in the average particle diameter of the two particles, that is, because the average particle diameter of the crystalline carbon is larger than the average particle diameter of the amorphous silicon particles, Figure 3 As shown in the figure, the surface of the crystalline carbon particles may be prepared in a shape such that amorphous silicon particles are coated.
또한, 본 발명의 방법에 있어서, 상기 규소계 복합 전구체를 열처리하는 단계(S5)는 400℃ 내지 1000℃, 바람직하게는 500℃ 내지 800℃ 온도에서, 약 10분 내지 1시간, 바람직하게는 20분 내지 1시간일 수 있다.Further, in the method of the present invention, the step (S5) of heat treating the silicon-based composite precursor is at a temperature of 400 ℃ to 1000 ℃, preferably 500 ℃ to 800 ℃, about 10 minutes to 1 hour, preferably 20 It may be from minutes to 1 hour.
만약, 상기 열처리 온도가 400℃ 미만인 경우 온도가 너무 낮아 탄화 공정이 충분히 일어나지 않아 비정질 탄소 코팅층을 형성하기 어려우며, 1000℃를 초과하는 경우 온도가 너무 높아 전구체에 포함된 비정질 탄소 코팅층의 결정성이 증가하는 문제점이 있다. If the heat treatment temperature is less than 400 ° C., the temperature is so low that the carbonization process does not occur sufficiently, making it difficult to form an amorphous carbon coating layer. If the temperature exceeds 1000 ° C., the crystallinity of the amorphous carbon coating layer included in the precursor is increased. There is a problem.
상기 열처리 단계는 질소 가스, 아르곤 가스, 헬륨 가스, 크립톤 가스 또는 크세논 가스 등이 존재하는 불활성 분위기에서 수행하는 것이 바람직하다.The heat treatment step is preferably performed in an inert atmosphere in which nitrogen gas, argon gas, helium gas, krypton gas, or xenon gas is present.
또한, 본 발명의 일 실시예에서는 In addition, in one embodiment of the present invention
상기 본 발명의 방법에 의해 제조된 리튬 이차전지용 음극활물질로서,As a negative electrode active material for a lithium secondary battery produced by the method of the present invention,
비정질 탄소 코팅층(5); 및An amorphous carbon coating layer 5; And
상기 비정질 탄소 코팅층(5) 내부에 포함된 1 이상의 비정질 규소입자(1)로 이루어진 규소 복합체를 포함하는 리튬 이차전지용 음극활물질(10)을 제공한다 (도 1 참조).Provided is an anode active material 10 for a lithium secondary battery including a silicon composite including one or more amorphous silicon particles 1 included in the amorphous carbon coating layer 5 (see FIG. 1).
이때, 상기 비정질 탄소 코팅층 내부에 포함된 상기 비정질 규소입자는 상기 단일 입자 또는 상기 단일 입자로 이루어진 1차 비정질 규소 입자가 응집되어 형성된 2차 비정질 규소입자를 포함할 수 있다. 상기 비정질 규소입자는 비정질 탄소 코팅층 내부에 균일하게 분산되어 있을 수 있다.In this case, the amorphous silicon particles included in the amorphous carbon coating layer may include secondary amorphous silicon particles formed by agglomeration of the single particles or primary amorphous silicon particles formed of the single particles. The amorphous silicon particles may be uniformly dispersed in the amorphous carbon coating layer.
구체적으로, 상기 비정질 규소입자의 평균입경은 5nm 내지 500nm, 구체적으로 20nm 내지 200nm일 수 있다. 상기 비정질 규소입자는 음극활물질 전체 중량에 대하여 1 내지 95 중량%로 포함될 수 있고, 구체적으로는 5 내지 90 중량%로 포함될 수 있다.Specifically, the average particle diameter of the amorphous silicon particles may be 5nm to 500nm, specifically 20nm to 200nm. The amorphous silicon particles may be included in an amount of 1 to 95% by weight, and specifically 5 to 90% by weight, based on the total weight of the negative electrode active material.
또한, 상기 1 이상의 비정질 규소입자 : 비정질 탄소 코팅층의 중량비는 5:90 내지 90:10, 구체적으로 10:90 내지 80:20의 범위일 수 있다. In addition, the weight ratio of the at least one amorphous silicon particle: amorphous carbon coating layer may be in the range of 5:90 to 90:10, specifically 10:90 to 80:20.
또한, 상기 음극활물질은 상기 비정질 탄소 코팅층 내부에 결정질 또는 상기 비정질 탄소 코팅층을 형성하는 것과 상이한 비정질 탄소로 이루어진 군으로부터 선택된 적어도 하나 이상의 전도성 탄소계 물질을 추가로 포함할 수 있다.In addition, the negative electrode active material may further include at least one conductive carbon-based material selected from the group consisting of crystalline or amorphous carbon different from forming the amorphous carbon coating layer inside the amorphous carbon coating layer.
상기 전도성 탄소계 물질은 음극활물질 전체 중량을 기준으로 0.1 중량% 내지 90 중량%로 포함될 수 있다.The conductive carbon-based material may be included in an amount of 0.1 wt% to 90 wt% based on the total weight of the negative electrode active material.
구체적으로, 본 발명의 일 실시예에서는 Specifically, in one embodiment of the present invention
상기 본 발명의 방법에 의해 제조된 리튬 이차전지용 음극활물질로서, As a negative electrode active material for a lithium secondary battery produced by the method of the present invention,
비정질 탄소 코팅층(15); 및 상기 비정질 탄소 코팅층 내부에 포함된 1 이상의 비정질 규소입자(11) 및 비정질 탄소(13)로 이루어진 규소 복합체를 포함하는 리튬 이차전지용 음극활물질(50)을 제공한다 (도 2 참조).An amorphous carbon coating layer 15; And it provides a negative electrode active material 50 for a lithium secondary battery comprising a silicon composite consisting of one or more amorphous silicon particles 11 and amorphous carbon 13 contained in the amorphous carbon coating layer (see FIG. 2).
상기 비정질 탄소는 음극활물질 전체 중량을 기준으로 0.1 내지 50 중량%로 포함될 수 있다. 상기 비정질 탄소의 함량이 0.1 중량% 미만인 경우 전도성 탄소계 물질을 첨가함에 따른 전기 전도성 개선 효과를 기재하기 어렵고, 50 중량%를 초과하는 경우 최종 음극활물질의 가역 용량이 낮아지는 문제가 있다.The amorphous carbon may be included in 0.1 to 50% by weight based on the total weight of the negative electrode active material. When the content of the amorphous carbon is less than 0.1% by weight, it is difficult to describe the effect of improving the electrical conductivity by adding the conductive carbonaceous material, and when the content exceeds 50% by weight, the reversible capacity of the final negative electrode active material is lowered.
또한, 본 발명의 일 실시예에서는 In addition, in one embodiment of the present invention
상기 본 발명의 방법에 의해 제조된 리튬 이차전지용 음극활물질로서, As a negative electrode active material for a lithium secondary battery produced by the method of the present invention,
비정질 탄소 코팅층(115); 및 상기 비정질 탄소 코팅층 내부에 포함된 1 이상의 비정질 규소입자(111) 및 결정질 탄소(117)를 포함하며, 상기 1 이상의 비정질 규소 입자(111)는 결정질 탄소(117)에 분포되어 있는 규소 복합체를 포함하는 리튬 이차전지용 음극활물질(100)을 제공한다 (도 3 참조). An amorphous carbon coating layer 115; And at least one amorphous silicon particle 111 and crystalline carbon 117 included in the amorphous carbon coating layer, wherein the at least one amorphous silicon particle 111 includes a silicon composite distributed in the crystalline carbon 117. To provide a negative electrode active material 100 for a lithium secondary battery (see Figure 3).
상기 결정질 탄소는 구형/판상형의 천연 흑연 내지는 인조 흑연 입자를 포함할 수 있다.The crystalline carbon may include spherical / plate-shaped natural graphite or artificial graphite particles.
상기 결정질 탄소의 평균입경(D50)은 300㎚ 내지 30㎛이다. The average particle diameter (D50) of the crystalline carbon is 300 nm to 30 μm.
만약, 상기 결정질 탄소의 평균입경이 300㎚ 미만인 경우, 구조 지지체로서의 역할이 감소할 수 있고, 30㎛ 를 초과하는 경우 최종 음극활물질의 평균입경이 증가하여 이차 전지 제조 시 균일한 코팅 공정을 실시하기 어려울 수 있다.If the average particle diameter of the crystalline carbon is less than 300 nm, the role as a structural support may be reduced, and if the average particle diameter exceeds 30 μm, the average particle size of the final negative electrode active material is increased to perform a uniform coating process in manufacturing a secondary battery. It can be difficult.
상기 결정질 탄소는 음극활물질 전체 중량을 기준으로 10 내지 90 중량%로 포함될 수 있다. 상기 결정질 탄소의 함량이 10 중량% 미만인 경우 결정질 탄소를 첨가함에 따른 전기 전도성 개선 효과 및 구조 지지체의 역할을 기대하기 어렵고, 결정질 탄소의 함량이 90 중량%를 초과하는 경우 최종 음극활물질의 가역 용량이 낮아지는 문제가 있다.The crystalline carbon may be included in 10 to 90% by weight based on the total weight of the negative electrode active material. When the content of the crystalline carbon is less than 10% by weight, it is difficult to expect the effect of improving the electrical conductivity and the role of the structural support by adding crystalline carbon, when the content of the crystalline carbon exceeds 90% by weight of the reversible capacity of the final negative electrode active material There is a problem of being lowered.
또한, 본 발명의 음극활물질의 평균입경(D50)은 50㎚ 내지 35㎛ 이다.In addition, the average particle diameter (D50) of the negative electrode active material of the present invention is 50nm to 35㎛.
구체적으로 본 발명의 음극활물질이 비정질 탄소 입자, 또는 비정질 탄소 입자 및 비정질 탄소를 포함하는 경우 (도 1 및 2 참조), 음극활물질의 평균입경(D50)은 50㎚ 내지 30㎛ 이고, 본 발명의 음극활물질이 비정질 탄소 입자 및 결정질 탄소를 포함하는 경우 (도 3 참조), 음극활물질의 평균입경(D50)은 500㎚ 내지 35㎛ 이다.Specifically, when the negative electrode active material of the present invention includes amorphous carbon particles, or amorphous carbon particles and amorphous carbon (see FIGS. 1 and 2), the average particle diameter (D50) of the negative electrode active material is 50 nm to 30 μm, and When the negative electrode active material contains amorphous carbon particles and crystalline carbon (see FIG. 3), the average particle diameter (D50) of the negative electrode active material is 500 nm to 35 μm.
음극활물질의 평균입경이 상기 범위 내일 경우에, 상기 음극활물질의 충방전 중 발생하는 부피팽창에 의한 실리콘의 스트레스를 줄일 수 있으며 가역 용량이 증가하며, 리튬과의 반응시 부피 팽창이 억제되어 사이클 수명 특성이 향상된다. 만약, 상기 음극활물질의 평균입경이 50nm 미만인 경우, 비표면적이 너무 커져 가역용량의 손실이 발생하게 되며, 35㎛를 초과하면 부피팽창에 의한 스트레스로 음극활물질 자체에 크랙 및 파쇄가 매우 쉽게 일어나며, 상기 입자의 크기가 커서 리튬과의 반응 시 부피 팽창이 심해져 전체 구상의 입자가 부피팽창을 완충시키는데 있어 효율성이 떨어지게 된다.When the average particle diameter of the negative electrode active material is within the above range, it is possible to reduce the stress of the silicon due to volume expansion generated during charging and discharging of the negative electrode active material, to increase the reversible capacity, and to inhibit the volume expansion during reaction with lithium, thereby improving cycle life. Characteristics are improved. If the average particle diameter of the negative electrode active material is less than 50 nm, the specific surface area is too large to cause a loss of reversible capacity. If the average particle diameter exceeds 35 μm, cracking and crushing of the negative electrode active material itself occurs very easily due to the stress caused by volume expansion. As the particle size is large, the volume expansion becomes severe upon reaction with lithium, thereby decreasing efficiency in buffering the volume expansion of the whole spherical particles.
또한, 본 발명의 음극활물질의 비표면적(BET)은 0.5㎡/g 내지 20㎡/g일 수 있다. 이때 상기 비표면적이 20㎡/g을 초과하게 되면 충방전 시 활물질 표면에서 전해액과 리튬 이온의 비가역 반응을 하여 리튬 이온의 소모를 발생시키므로 초기 효율 감소의 원인이 될 수 있다. In addition, the specific surface area (BET) of the negative electrode active material of the present invention may be 0.5 m 2 / g to 20 m 2 / g. In this case, when the specific surface area exceeds 20 m 2 / g, an irreversible reaction between the electrolyte and lithium ions occurs on the surface of the active material during charge and discharge, thereby causing consumption of lithium ions, which may cause initial efficiency reduction.
전술한 바와 같이, 본 발명의 방법에 의해 제조된 비정질 규소입자-비정질 탄소 코팅층을 포함하는 복합체로 이루어진 음극활물질은 전체적인 공정 온도가 낮아 규소입자의 결정성 성장 및 산화를 방지할 수 있어, 종래 결정질 규소계 나노입자-탄소 복합체에 비해 수명 특성과 부피 팽창 특성이 우수하고, 일반적인 결정질 규소계 나노입자-탄소 복합체에 비해 초기 효율이 우수하다는 장점이 있다. 또한, 분쇄 과정 중의 규소계 활물질의 산화를 방지하여, 일반적인 결정질 규소계 나노입자-탄소 복합체에 비해 초기 효율이 우수하고, 종래 결정질 규소계 나노입자-탄소 복합체에 비해 방전 용량 (mAh/g)이 크다는 장점이 있다. 특히, 종래 음극활물질로 흑연을 사용한 경우, 흑연 자체의 방전 용량이 360 mAh/g으로 규소 대비 크지 않고, 방전 용량을 높이기 위해 복합해 주는 규소의 양을 늘리게 되면 흑연 표면 부분에 규소입자가 집중되어 수명 특성을 열화시키는 원인이 될 수 있다. As described above, the negative electrode active material made of the composite including the amorphous silicon particle-amorphous carbon coating layer prepared by the method of the present invention can lower the overall process temperature to prevent the crystalline growth and oxidation of the silicon particles, the conventional crystalline Compared to the silicon-based nanoparticle-carbon composites, there is an advantage in that the life and volume expansion characteristics are excellent, and the initial efficiency is superior to the general crystalline silicon-based nanoparticle-carbon composites. In addition, by preventing the oxidation of the silicon-based active material during the grinding process, the initial efficiency is superior to the conventional crystalline silicon-based nanoparticles-carbon composites, the discharge capacity (mAh / g) compared to the conventional crystalline silicon-based nanoparticles-carbon composites There is a big advantage. In particular, when graphite is used as a negative electrode active material, the discharge capacity of the graphite itself is 360 mAh / g, which is not large compared to silicon, and when the amount of silicon compounded to increase the discharge capacity is increased, silicon particles are concentrated on the graphite surface. It may cause deterioration of lifespan characteristics.
하지만, 본 발명의 방법에 의해 제조된 복합체는 탄소 매트릭스 내에 규소입자가 고르게 분포되어 수명 특성의 열화를 방지할 수 있다.However, the composite produced by the method of the present invention can evenly distribute the silicon particles in the carbon matrix to prevent degradation of life characteristics.
더욱이, 본원발명의 방법에 의해 제조된 음극활물질은 내부에 흑연 입자 또는 도전재와 같은 전도성 물질을 더 포함함으로써, 도전성 향상 효과를 추가로 구현할 수 있다.Furthermore, the negative electrode active material produced by the method of the present invention further includes a conductive material such as graphite particles or a conductive material therein, thereby further realizing a conductivity improving effect.
또한, 본 발명의 방법에서는 In addition, in the method of the present invention
집전체, 및Current collector, and
상기 집전체의 적어도 일면에 형성된 본 발명의 음극 활물질을 포함하는 음극을 제공한다.It provides a negative electrode comprising the negative electrode active material of the present invention formed on at least one surface of the current collector.
이때, 본 발명의 일 실시예에 따른 상기 음극은 당 분야에 알려져 있는 통상적인 방법으로 제조할 수 있다. 예를 들면, 상기 음극 활물질에 용매, 필요에 따라 바인더 및 도전재를 선택적으로 혼합 및 교반하여 슬러리를 제조한 후 이를 금속 재료의 집전체에 도포(코팅)하고 압축한 뒤 건조하여 음극을 제조할 수 있다.At this time, the negative electrode according to an embodiment of the present invention can be prepared by a conventional method known in the art. For example, a slurry is prepared by selectively mixing and stirring a solvent, a binder, and a conductive material in the negative electrode active material, if necessary, and then applying (coating) to a current collector of a metal material, compressing, and drying to prepare a negative electrode. Can be.
본 발명의 일 실시예에 따르면, 상기 바인더는 음극 활물질 입자들을 결착시켜 성형체를 유지하기 위하여 사용되는 것으로서, 폴리테트라플루오로에틸렌(PTFE), 폴리비닐리덴 플루오라이드(PVdF), SBR(styrene butadiene rubber) 등과 같은 바인더가 사용된다. According to one embodiment of the present invention, the binder is used to bind the negative electrode active material particles to maintain the molded body, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), styrene butadiene rubber Binders) are used.
본 발명의 일 실시예에 따르면, 상기 도전재는 천연 흑연, 인조흑연, 카본블랙, 아세틸렌 블랙, 케첸 블랙, 채널 블랙, 퍼네이스 블랙, 램프 블랙, 서멀블랙, 탄소 나노튜브, 플러렌, 탄소 섬유, 금속 섬유, 불화 카본, 알루미늄, 니켈 분말, 산화 아연, 티탄산 칼륨, 산화 티탄 및 폴리페닐렌 유도체로 이루어진 군에서 선택된 어느 하나 또는 이들 중 2종 이상의 혼합물일 수 있으며, 바람직하게는 카본블랙일 수 있다.According to one embodiment of the invention, the conductive material is natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon nanotube, fullerene, carbon fiber, metal Fiber, carbon fluoride, aluminum, nickel powder, zinc oxide, potassium titanate, titanium oxide and polyphenylene derivatives may be any one selected from the group consisting of, or a mixture of two or more thereof, preferably carbon black.
본 발명의 일 실시예에서 상기 음극집전체는 전지에 화학적 변화를 유발하지 않으면서 높은 도전성을 가지는 것이라면 특별히 제한되는 것은 아니며, 예를 들어, 구리, 스테인레스 스틸, 알루미늄, 니켈, 티탄, 소성 탄소, 구리나 스테인레스 스틸의 표면에 탄소, 니켈, 티탄, 은 등으로 표면처리한 것, 알루미늄-카드뮴 합금 등이 사용될 수 있다. 또, 상기 음극 집전체는 통상적으로 3 내지 500㎛의 두께를 가질 수 있으며, 양극 집전체와 마찬가지로, 상기 집전체 표면에 미세한 요철을 형성하여 음극활물질의 결합력을 강화시킬 수도 있다. 예를 들어, 필름, 시트, 호일, 네트, 다공질체, 발포체, 부직포체 등 다양한 형태로 사용될 수 있다.In one embodiment of the present invention, the negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, Surface treated with carbon, nickel, titanium, silver, or the like on the surface of copper or stainless steel, aluminum-cadmium alloy, etc. may be used. In addition, the negative electrode current collector may have a thickness of about 3 to 500 μm, and like the positive electrode current collector, fine concavities and convexities may be formed on the surface of the current collector to enhance the bonding force of the negative electrode active material. For example, it can be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven body.
또한, 본 발명의 일 실시예에서는In addition, in one embodiment of the present invention
상기 음극을 이용하여, 양극, 음극, 상기 양극과 음극 사이에 개재된 세퍼레이터 및 리튬염이 용해되어 있는 비수성 전해액을 포함하는 리튬 이차전지를 제공한다. By using the negative electrode, there is provided a lithium secondary battery including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode and a non-aqueous electrolyte in which lithium salt is dissolved.
이때, 본 발명의 리튬 이차전지에 있어서, 사용되는 양극 및 전해질은 당 분야에 통상적으로 사용되는 재료를 이용할 수 있으며, 이에 제한되는 것은 아니다.In this case, in the lithium secondary battery of the present invention, the positive electrode and the electrolyte used may be a material commonly used in the art, but is not limited thereto.
구체적으로, 양극은 양극 집전체 상에 양극활물질, 바인더, 도전재 및 용매 등을 포함하는 양극 슬러리를 코팅한 후, 건조 및 압연하여 제조할 수 있다. Specifically, the positive electrode may be prepared by coating a positive electrode slurry including a positive electrode active material, a binder, a conductive material, a solvent, and the like on a positive electrode current collector, followed by drying and rolling.
상기 양극 활물질은 리튬의 가역적인 인터칼레이션 및 디인터칼레이션이 가능한 화합물로서, 구체적으로는 코발트, 망간, 니켈 또는 알루미늄과 같은 1종 이상의 금속과 리튬을 포함하는 리튬 복합금속 산화물을 포함할 수 있다. 보다 구체적으로, 상기 리튬 복합금속 산화물은 리튬-망간계 산화물(예를 들면, LiMnO2, LiMn2O4 등), 리튬-코발트계 산화물(예를 들면, LiCoO2 등), 리튬-니켈계 산화물(예를 들면, LiNiO2 등), 리튬-니켈-망간계 산화물(예를 들면, LiNi1 - YMnYO2(여기에서, 0<Y<1), LiMn2 - zNizO4(여기에서, 0＜Z＜2) 등), 리튬-니켈-코발트계 산화물(예를 들면, LiNi1 - Y1CoY1O2(여기에서, 0<Y1<1) 등), 리튬-망간-코발트계 산화물(예를 들면, LiCo1-Y2MnY2O2(여기에서, 0<Y2<1), LiMn2 - z1Coz1O4(여기에서, 0＜Z1＜2) 등), 리튬-니켈-망간-코발트계 산화물(예를 들면, Li(NipCoqMnr1)O2(여기에서, 0＜p＜1, 0＜q＜1, 0＜r1＜1, p+q+r1=1) 또는 Li(Nip1Coq1Mnr2)O4(여기에서, 0＜p1＜2, 0＜q1＜2, 0＜r2＜2, p1+q1+r2=2) 등), 또는 리튬-니켈-코발트-전이금속(M) 산화물(예를 들면, Li(Nip2Coq2Mnr3MS2)O2(여기에서, M은 Al, Fe, V, Cr, Ti, Ta, Mg 및 Mo로 이루어지는 군으로부터 선택되고, p2, q2, r3 및 s2는 각각 독립적인 원소들의 원자분율로서, 0＜p2＜1, 0＜q2＜1, 0＜r3＜1, 0＜s2＜1, p2+q2+r3+s2=1이다) 등) 등을 들 수 있으며, 이들 중 어느 하나 또는 둘 이상의 화합물이 포함될 수 있다. 이중에서도 전지의 용량 특성 및 안정성을 높일 수 있다는 점에서 상기 리튬 복합금속 산화물은 LiCoO2, LiMnO2, LiNiO2, 리튬 니켈망간코발트 산화물(예를 들면, Li(Ni0.6Mn0.2Co0.2)O2, Li(Ni0.5Mn0.3Co0.2)O2, 또는 Li(Ni0.8Mn0.1Co0.1)O2 등), 또는 리튬 니켈코발트알루미늄 산화물(예를 들면, Li(Ni0 . 8Co0 . 15Al0 . 05O2 등) 등일 수 있으며, 리튬 복합금속 산화물을 형성하는 구성원소의 종류 및 함량비 제어에 따른 개선 효과의 현저함을 고려할 때 상기 리튬 복합금속 산화물은 Li(Ni0.6Mn0.2Co0.2)O2, Li(Ni0.5Mn0.3Co0.2)O2, Li(Ni0.7Mn0.15Co0.15)O2 또는 Li(Ni0.8Mn0.1Co0.1)O2 등일 수 있으며, 이들 중 어느 하나 또는 둘 이상의 혼합물이 사용될 수 있다.The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and may specifically include a lithium composite metal oxide containing lithium and one or more metals such as cobalt, manganese, nickel or aluminum. have. More specifically, the lithium composite metal oxide is a lithium-manganese oxide (eg, LiMnO 2 , LiMn 2 O 4, etc.), lithium-cobalt oxide (eg, LiCoO 2, etc.), lithium-nickel oxide (for example, LiNiO 2 and the like), lithium-nickel-manganese-based oxide (for example, LiNi 1-Y Mn Y O 2 (where, 0 <Y <1), LiMn 2-z Ni z O 4 ( here, 0 <Z <2) and the like), lithium-nickel-cobalt oxide (e.g., LiNi 1-Y1 Co Y1 O 2 (here, 0 <Y1 <1) and the like), lithium-manganese-cobalt oxide (e. g., LiCo 1-Y2 Mn Y2 O 2 (here, 0 <Y2 <1), LiMn 2 - z1 Co z1 O 4 ( here, 0 <z1 <2) and the like), lithium-nickel Manganese-cobalt-based oxides (e.g., Li (Ni p Co q Mn r1 ) O 2 , where 0 <p <1, 0 <q <1, 0 <r1 <1, p + q + r1 = 1) or Li (Ni p1 Co q1 Mn r2 ) O 4 (where 0 <p1 <2, 0 <q1 <2, 0 <r2 <2, p1 + q1 + r2 = 2, etc.), or lithium- Nickel-cobalt-transition metal (M) oxide (e.g. Li (Ni p2 Co q2 Mn r3 M S2 ) O 2 (excitation Where M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg and Mo, and p2, q2, r3 and s2 are atomic fractions of the independent elements, respectively, 0 <p2 <1, 0 <Q2 <1, 0 <r3 <1, 0 <s2 <1, p2 + q2 + r3 + s2 = 1), etc.), and any one or two or more of these compounds may be included. Among the lithium composite metal oxides, LiCoO 2 , LiMnO 2 , LiNiO 2 , and lithium nickel manganese cobalt oxides (eg, Li (Ni 0.6 Mn 0.2 Co 0.2 ) O 2 may be improved in capacity and stability of the battery. , Li (Ni 0.5 Mn 0.3 Co 0.2) O 2 or Li (Ni 0.8 Mn 0.1 Co 0.1 ) O 2 ), or lithium nickel cobalt aluminum oxide (e.g., Li (Ni 0. 8 Co 0. 15 Al 0 . 05 O 2, etc.) and the like, considering the remarkable also in the improvement according to the kind and content ratio control of constituent elements forming the lithium composite metal oxide, wherein the lithium composite metal oxide is Li (Ni 0.6 Mn 0.2 Co 0.2 ) O 2 , Li (Ni 0.5 Mn 0.3 Co 0.2 ) O 2 , Li (Ni 0.7 Mn 0.15 Co 0.15 ) O 2, or Li (Ni 0.8 Mn 0.1 Co 0.1 ) O 2 , and the like, and any one or a mixture of two or more thereof may be used. have.
상기 양극 활물질은 양극 슬러리의 전체 중량을 기준으로 80 중량% 내지 99중량%로 포함될 수 있다. The cathode active material may be included in an amount of 80 wt% to 99 wt% based on the total weight of the cathode slurry.
상기 도전재는 통상적으로 양극 슬러리의 전체 중량을 기준으로 1 내지 30 중량%로 첨가된다. 이러한 도전재는 당해 전지에 화학적 변화를 유발하지 않으면서 도전성을 가진 것이라면 특별히 제한되는 것은 아니며, 예를 들어, 그라파이트; 카본블랙, 아세틸렌 블랙, 케첸 블랙, 채널 블랙, 퍼니스 블랙, 램프 블랙, 서멀 블랙 등의 탄소계 물질; 탄소 섬유나 금속 섬유 등의 도전성 섬유; 불화 카본, 알루미늄, 니켈 분말 등의 금속 분말; 산화아연, 티탄산 칼륨 등의 도전성 위스키; 산화 티탄 등의 도전성 금속 산화물; 폴리페닐렌 유도체 등의 도전성 소재 등이 사용될 수 있다. 시판되고 있는 도전재의 구체적인 예로는 아세틸렌 블랙 계열인 쉐브론 케미칼 컴퍼니(Chevron Chemical Company)나 덴카 블랙(Denka Singapore Private Limited), 걸프 오일 컴퍼니(Gulf Oil Company) 제품 등), 케트젠블랙(Ketjenblack), EC 계열(아르막 컴퍼니(Armak Company) 제품), 불칸(Vulcan) XC-72(캐보트 컴퍼니(Cabot Company) 제품) 및 수퍼(Super) P(Timcal 사 제품) 등이 있다.The conductive material is typically added at 1 to 30% by weight based on the total weight of the positive electrode slurry. Such a conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include graphite; Carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used. Specific examples of commercially available conductive materials include Chevron Chemical Company, Denka Singapore Private Limited, Gulf Oil Company, Ketjenblack and EC, which are acetylene black series. Family (Armak Company), Vulcan XC-72 (manufactured by Cabot Company) and Super P (manufactured by Timcal).
상기 바인더는 활물질과 도전재 등의 결합과 집전체에 대한 결합에 조력하는 성분으로서, 통상적으로 양극 슬러리의 전체 중량을 기준으로 1 내지 30 중량%로 첨가된다. 이러한 바인더의 예로는, 폴리비닐리덴플루오라이드, 폴리비닐알코올, 카르복시메틸셀룰로우즈(CMC), 전분, 히드록시프로필셀룰로우즈, 재생 셀룰로우즈, 폴리비닐피롤리돈, 테트라플루오로에틸렌, 폴리에틸렌, 폴리프로필렌, 에틸렌-프로필렌-디엔 테르 폴리머(EPDM), 술폰화 EPDM, 스티렌-부타디엔 고무, 불소 고무, 다양한 공중합체 등을 들 수 있다.The binder is a component that assists in bonding the active material and the conductive material and bonding to the current collector, and is generally added in an amount of 1 to 30 wt% based on the total weight of the positive electrode slurry. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, Polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluorine rubber, various copolymers, and the like.
상기 용매는 NMP(N-methyl-2-pyrrolidone) 등의 유기용매를 포함할 수 있으며, 상기 양극 활물질, 및 선택적으로 바인더 및 도전재 등을 포함할 때 바람직한 점도가 되는 양으로 사용될 수 있다. 예를 들면, 양극 활물질, 및 선택적으로 바인더 및 도전재를 포함하는 고형분의 농도가 50 중량% 내지 95 중량%, 바람직하게 70 중량% 내지 90 중량%가 되도록 포함될 수 있다.The solvent may include an organic solvent such as N-methyl-2-pyrrolidone (NMP), and may be used in an amount that becomes a desirable viscosity when including the cathode active material, and optionally a binder and a conductive material. For example, the concentration of the positive electrode active material and, optionally, the solid content including the binder and the conductive material may be included in an amount of 50 wt% to 95 wt%, preferably 70 wt% to 90 wt%.
상기 전해액은 리튬 이차전지 제조 시에 통상적으로 사용되는 것으로, 비수계 유기 용매와 리튬염을 포함한다.The electrolyte is commonly used in manufacturing a lithium secondary battery, and includes a non-aqueous organic solvent and a lithium salt.
상기 비수계 유기 용매로는, 전지의 충방전 과정에서 산화 반응 등에 의한 분해가 최소화될 수 있고, 첨가제와 함께 목적하는 특성을 발휘할 수 있는 것이라면 특별히 제한하지 않으며, 그 대표적인 예로 카보네이트계 화합물 또는 프로피오네이트계 화합물 등을 단독으로 사용하거나, 또는 2종 이상 혼합하여 사용할 수 있다. The non-aqueous organic solvent is not particularly limited as long as it can minimize decomposition by an oxidation reaction or the like in the process of charging and discharging a battery, and can exhibit desired properties with an additive. Examples thereof include a carbonate-based compound or propio. Nate type compounds etc. can be used individually, or can mix and use 2 or more types.
이러한 카보네이트계 화합물은 그 대표적인 예로, 디메틸 카보네이트(DMC), 디에틸 카보네이트(DEC), 디프로필 카보네이트(DPC), 메틸프로필 카보네이트(MPC), 에틸프로필 카보네이트(EPC), 메틸에틸 카보네이트(MEC), 에틸렌 카보네이트(EC), 프로필렌 카보네이트(PC), 부틸렌 카보네이트(BC) 및 비닐렌 카보네이트(VC)로 이루어진 군에서 선택된 어느 하나 또는 이들 중 2종 이상의 혼합물을 들 수 있다.Examples of such carbonate compounds include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), Ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) and vinylene carbonate (VC), any one selected from the group consisting of, or a mixture of two or more thereof.
또한, 상기 프로피오네이트계 화합물은 그 대표적인 예로 에틸 프로피오네이트(EP), 프로필 프로피오네이트(PP), n-프로필 프로피오네이트, iso-프로필 프로피오네이트, n-부틸 프로피오네이트, iso-부틸 프로피오네이트 및 tert-부틸 프로피오네이트로 이루어진 군에서 선택된 어느 하나 또는 이들 중 2종 이상의 혼합물을 들 수 있다.In addition, the propionate-based compound may be ethyl propionate (EP), propyl propionate (PP), n-propyl propionate, iso-propyl propionate, n-butyl propionate, iso One or a mixture of two or more selected from the group consisting of -butyl propionate and tert-butyl propionate.
이외에도, 상기 비수계 유기용매로는, 예를 들어, N-메틸-2-피롤리돈, 프로필렌 카보네이트, 에틸렌 카보네이트, 부틸렌 카보네이트, 디메틸 카보네이트, 디에틸 카보네이트, 감마-부티로락톤, 1,2-디메톡시 에탄, 2-메틸 테트라하이드로푸란, 디메틸술폭시드, 1,3-디옥소런, 포름아미드, 디메틸포름아미드, 디옥소런, 아세토니트릴, 니트로메탄, 포름산 메틸, 초산메틸, 인산 트리에스테르, 트리메톡시 메탄, 디옥소런 유도체, 설포란, 메틸 설포란, 1,3-디메틸-2-이미다졸리디논, 프로필렌 카보네이트 유도체, 테트라하이드로푸란 유도체, 에테르, 프로피온산 메틸, 프로피온산 에틸 등이 사용될 수 있다. In addition, as the non-aqueous organic solvent, for example, N-methyl-2-pyrrolidone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2 Dimethoxy ethane, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolon, formamide, dimethylformamide, dioxolon, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester , Trimethoxy methane, dioxorone derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ether, methyl propionate, ethyl propionate and the like Can be.
또한, 상기 리튬염은 양이온으로 Li+를 포함하고, 음이온으로는 F-, Cl-, Br-, I-, NO3 -, N(CN)2 -, BF4 -, ClO4 -, AlO4 -, AlCl4 -, PF6 -, SbF6 -, AsF6 -, BF2C2O4 -, BC4O8 -, (CF3)2PF4 -, (CF3)3PF3 -, (CF3)4PF2 -, (CF3)5PF-, (CF3)6P-, CF3SO3 -, C4F9SO3 -, CF3CF2SO3 -, (CF3SO2)2N-, (F2SO2)2N-, CF3CF2(CF3)2CO-, (CF3SO2)2CH-, CF3(CF2)7SO3 -, CF3CO2 -, CH3CO2 -, SCN- 및 (CF3CF2SO2)2N-로 이루어진 군으로부터 선택된 적어도 어느 하나를 포함할 수 있다. 상기 리튬염은 1종 또는 필요에 따라서 2종 이상을 혼합하여 사용할 수도 있다. 상기 리튬염은 통상적으로 사용 가능한 범위 내에서 적절히 변경할 수 있으나, 최적의 전극 표면의 부식 방지용 피막 형성 효과를 얻기 위하여, 전해액 내에 0.8 M 내지 1.5M의 농도로 포함할 수 있다. Further, as the anion wherein the lithium salt comprises a Li + cation, are F -, Cl -, Br - , I -, NO 3 -, N (CN) 2 -, BF 4 -, ClO 4 -, AlO 4 -, AlCl 4 -, PF 6 -, SbF 6 -, AsF 6 -, BF 2 C 2 O 4 -, BC 4 O 8 -, (CF 3) 2 PF 4 -, (CF 3) 3 PF 3 -, (CF 3) 4 PF 2 - , (CF 3) 5 PF -, (CF 3) 6 P -, CF 3 SO 3 -, C 4 F 9 SO 3 -, CF 3 CF 2 SO 3 -, (CF 3 SO 2) 2 N -, ( F 2 SO 2) 2 N -, CF 3 CF 2 (CF 3) 2 CO -, (CF 3 SO 2) 2 CH -, CF 3 (CF 2) 7 SO 3 -, CF 3 CO 2 -, CH 3 CO 2 -, SCN - can include at least one selected from the group consisting of - and (CF 3 CF 2 SO 2) 2 N. The said lithium salt can also be used 1 type or in mixture of 2 or more types as needed. The lithium salt may be appropriately changed within a range generally available, but may be included in an electrolyte solution at a concentration of 0.8 M to 1.5 M in order to obtain an effect of forming an anti-corrosion coating on the surface of the electrode.
본 발명의 일 실시예에 따른 리튬 이차전지는 리튬금속 이차전지, 리튬이온 이차전지, 리튬폴리머 이차전지 또는 리튬이온폴리머 이차전지 등, 통상적인 리튬 이차전지들을 모두 포함할 수 있다.The lithium secondary battery according to the exemplary embodiment of the present invention may include all conventional lithium secondary batteries, such as a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.
또한, 본 발명의 리튬 이차전지의 외형은 특별한 제한이 없으나, 캔을 사용한 원통형, 각형, 파우치 (pouch)형 또는 코인 (coin)형 등이 될 수 있다.In addition, the external shape of the lithium secondary battery of the present invention is not particularly limited, but may be cylindrical, square, pouch type or coin type using a can.
본 발명의 리튬 이차전지는 각종 전자제품의 전원으로 사용될 수 있다. 예를 들어 휴대용 전화기, 핸드폰, 게임기, 휴대용 텔레비전, 노트북 컴퓨터, 계산기 등에 사용할 수 있으며, 이에 한정되는 것은 아니다. The lithium secondary battery of the present invention can be used as a power source for various electronic products. For example, the present invention may be used in a portable telephone, a mobile phone, a game console, a portable television, a laptop computer, a calculator, and the like, but is not limited thereto.
이하, 본 발명을 구체적으로 설명하기 위해 실시예를 들어 상세하게 설명하기로 한다. 그러나 본 발명에 따른 실시예는 여러 가지 다른 형태로 변형될 수 있으며, 본 발명의 범위가 아래에서 상술하는 실시예에 한정되는 것으로 해석되어서는 안 된다. 본 발명의 실시예는 당업계에서 평균적인 지식을 가진 자에게 본 발명을 보다 완전하게 설명하기 위해서 제공되는 것이다.Hereinafter, the present invention will be described in detail with reference to Examples. However, embodiments according to the present invention can be modified in many different forms, the scope of the present invention should not be construed as limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.
실시예Example
<음극 활물질의 제조><Production of Anode Active Material>
실시예 1Example 1
500℃ 및 760 Torr의 압력 조건하에서 실란 가스를 25 sccm/60min의 속도로 가하여 유리 기판 표면에 100nm 두께의 비정질 규소층을 증착하였다.Silane gas was added at a rate of 25 sccm / 60 min under a pressure condition of 500 ° C. and 760 Torr to deposit an amorphous silicon layer having a thickness of 100 nm on the surface of the glass substrate.
이어서, 비정질 규소층이 증착된 유리 기판을 아세톤이 담긴 비이커에 함침한 후, 초음파 분쇄기를 이용하여 100W 출력으로 상온에서 10 분 동안 초음파 분쇄를 실시하여, 평균입경(D50)이 100nm인 비정질 규소입자를 제조하였다. 그 다음, 60℃의 컨백션 오븐(convection oven)에서 아세톤을 휘발하여 분쇄된 비정질 규소 입자를 포집하였다.Subsequently, the glass substrate on which the amorphous silicon layer is deposited is impregnated in a beaker containing acetone, and then subjected to ultrasonic grinding for 10 minutes at room temperature at 100W output using an ultrasonic mill, thereby obtaining amorphous silicon particles having an average particle diameter (D50) of 100 nm. Was prepared. Then, acetone was volatilized in a convection oven at 60 ° C. to collect the pulverized amorphous silicon particles.
그 다음으로, 증류수 1L에 수크로오스 120g을 용해시켜 탄소계 전구체 용액을 제조한 후, 상기 분쇄된 비정질 규소입자 50g를 분산시켜 분산 용액을 제조하였다.Next, 120 g of sucrose was dissolved in 1 L of distilled water to prepare a carbon-based precursor solution, and then 50 g of the pulverized amorphous silicon particles were dispersed to prepare a dispersion solution.
상기 분산 용액을 220℃에서 20 mL/min 속도로 분무 건조하여 규소계 복합 전구체를 제조하였다.The dispersion solution was spray dried at a rate of 20 mL / min at 220 ° C. to prepare a silicon-based composite precursor.
그 다음으로, 상기 규소계 복합 전구체를 600℃에서 15분간 열처리하여, 비정질 탄소 코팅층(5)(50 중량%) 내부에 비정질 규소입자(1)(50 중량%)를 포함하는 평균입경(D5) 5㎛의 리튬 이차전지용 음극활물질(10)을 제조하였다(도 1 참조).Subsequently, the silicon-based composite precursor was heat-treated at 600 ° C. for 15 minutes, and the average particle diameter (D5) including amorphous silicon particles 1 (50% by weight) inside the amorphous carbon coating layer 5 (50% by weight). A 5 μm lithium secondary battery negative electrode active material 10 was prepared (see FIG. 1).
실시예 2Example 2
상기 실시예 1에서 탄소계 전구체 용액에 분쇄된 비정질 규소입자를 분산시킬 때, 비정질 탄소인 카본 블랙 2g을 함께 분산시켜 분산 용액을 제조하는 것을 제외하고는 상기 실시예 1과 마찬가지의 방법으로, 비정질 탄소 코팅층(15)(49 중량%) 내부에 비정질 규소입자(11)(49 중량%) 및 도전재(13)(2 중량%)를 포함하는 평균입경(D5) 5㎛의 리튬 이차전지용 음극활물질(50)을 제조하였다(도 2 참조).When dispersing the pulverized amorphous silicon particles in the carbon-based precursor solution in Example 1, in the same manner as in Example 1, except that 2g of carbon black which is amorphous carbon is dispersed together to prepare a dispersion solution, amorphous Cathode active material for lithium secondary battery having an average particle diameter (D5) of 5 μm including amorphous silicon particles 11 (49 wt%) and conductive material 13 (2 wt%) in the carbon coating layer 15 (49 wt%). 50 was prepared (see FIG. 2).
실시예 3Example 3
상기 실시예 1에서 탄소계 전구체 용액에 분쇄된 비정질 규소입자를 분산시킬 때, 결정질 탄소인 인조흑연 입자 200g을 함께 분산시켜 분산 용액을 제조하는 것을 제외하고는 상기 실시예 1과 마찬가지의 방법으로, 비정질 탄소 코팅층(115)(17 중량%) 내부에 비정질 규소입자(111)(17 중량%) 및 흑연 입자 코어(117)(66 중량%)를 포함하는 평균입경(D5) 21㎛의 리튬 이차전지용 음극활물질(100)을 제조하였다.When dispersing the pulverized amorphous silicon particles in the carbon-based precursor solution in Example 1, in the same manner as in Example 1 except for dispersing the artificial graphite particles of crystalline carbon together to prepare a dispersion solution, A lithium secondary battery having an average particle diameter (D5) of 21 μm including amorphous silicon particles 111 (17 wt%) and graphite particle core 117 (66 wt%) inside an amorphous carbon coating layer 115 (17 wt%). A negative electrode active material 100 was prepared.
비교예 1Comparative Example 1
상용 제품인 평균입경 44㎛의 규소 분말(Sigma-aldrich社)을 ball mill 방법을 통해 분쇄하여 나노 크기의 결정질 규소입자를 제조하였다. 이 때, milling media로는 직경이 3mm인 지르코니아 볼을 사용하였으며, 볼과 규소 분말의 비율을 1:1 질량비로 혼합하여 2시간 동안 분쇄하였다. 분쇄 후 결정질 규소입자의 평균입경은 150nm이었다.Nano-size crystalline silicon particles were prepared by pulverizing silicon powder (Sigma-aldrich) having an average particle diameter of 44 μm using a ball mill method. At this time, a zirconia ball having a diameter of 3mm was used as the milling media, and the ratio of the ball and the silicon powder was mixed in a 1: 1 mass ratio and pulverized for 2 hours. The average particle diameter of the crystalline silicon particles after grinding was 150 nm.
이어서, 수크로오스 120g을 증류수 1L에 용해시켜 탄소계 전구체 용액을 제조한 후, 상기 분쇄된 결정질 규소입자 50g을 분산시켜 분산 용액을 제조하였다.Subsequently, 120 g of sucrose was dissolved in 1 L of distilled water to prepare a carbon-based precursor solution, and then 50 g of the pulverized crystalline silicon particles were dispersed to prepare a dispersion solution.
상기 분산 용액을 220℃에서 20 mL/min 속도로 분무 건조하여 규소계 복합 전구체를 제조하였다.The dispersion solution was spray dried at a rate of 20 mL / min at 220 ° C. to prepare a silicon-based composite precursor.
그 다음으로, 상기 규소계 복합 전구체를 600℃에서 15분간 열처리하여, 비정질 탄소 코팅층 (50%) 내부에 비정질 탄소 코팅층 내부에 비정질 규소입자(50%)를 포함하는 평균입경(D5) 5㎛의 리튬 이차전지용 음극활물질을 제조하였다.Subsequently, the silicon-based composite precursor was heat-treated at 600 ° C. for 15 minutes to have an average particle diameter (D5) of 5 μm including amorphous silicon particles (50%) inside the amorphous carbon coating layer (50%) inside the amorphous carbon coating layer (50%). A negative electrode active material for a lithium secondary battery was prepared.
비교예 2.Comparative Example 2.
상기 비교예 1에서 탄소계 전구체 용액에 분쇄된 결정질 규소입자를 분산시킬 때, 카본 블랙 2g을 함께 분산시켜 분산 용액을 제조하는 것을 제외하고는 상기 비교예 1과 마찬가지의 방법으로, 비정질 탄소 코팅층(49%) 내부에 비정질 규소입자(49%) 및 카본블랙(2%)을 포함하는 평균입경(D5) 5㎛의 리튬 이차전지용 음극활물질을 제조하였다.When dispersing the pulverized crystalline silicon particles in the carbon-based precursor solution in Comparative Example 1, except for preparing a dispersion solution by dispersing 2g of carbon black, the amorphous carbon coating layer ( 49%) to prepare a negative active material for a lithium secondary battery having an average particle diameter (D5) of 5 μm including amorphous silicon particles (49%) and carbon black (2%).
비교예 3Comparative Example 3
상기 비교예 1에서 탄소계 전구체 용액에 분쇄된 결정질 규소입자를 분산시킬 때, 흑연 입자 200g을 함께 분산시켜 분산 용액을 제조하는 것을 제외하고는 상기 비교예 1과 마찬가지의 방법으로, 비정질 탄소 코팅층(17%) 내부에 비정질 규소입자(17%) 및 흑연 입자 (66%)를 포함하는 평균입경(D5) 21㎛의 리튬 이차전지용 음극활물질을 제조하였다.When dispersing the pulverized crystalline silicon particles in the carbon-based precursor solution in Comparative Example 1, except for preparing a dispersion solution by dispersing 200g of graphite particles together, in the same manner as in Comparative Example 1, the amorphous carbon coating layer ( 17%) to prepare a negative active material for a lithium secondary battery having an average particle diameter (D5) of 21 μm including amorphous silicon particles (17%) and graphite particles (66%).
<리튬 이차전지의 제조><Production of Lithium Secondary Battery>
실시예 4Example 4
(음극 제조)(Cathode production)
음극 활물질로 실시예 1에서 제조된 음극 활물질, 도전재로 아세틸렌 블랙, 바인더로 스티렌-부타디엔 고무(SBR), 증점제로 카르복시메틸셀룰로오스(CMC)를 96:1:2:1의 중량비로 혼합한 후, 이들을 용매인 물(H2O)과 함께 혼합하여 균일한 음극 활물질 슬러리를 제조하였다. The negative electrode active material prepared in Example 1 as a negative electrode active material, acetylene black as a conductive material, styrene-butadiene rubber (SBR) as a binder, and carboxymethyl cellulose (CMC) as a thickener were mixed in a weight ratio of 96: 1: 2: 1. And, these were mixed with water (H 2 O) as a solvent to prepare a uniform negative electrode active material slurry.
상기 제조된 음극 활물질 슬러리를 구리 집전체의 일면에 65 ㎛의 두께로 코팅하고, 건조 및 압연한 후 일정크기로 펀칭하여 음극을 제조하였다. The prepared negative electrode active material slurry was coated on one surface of a copper current collector to a thickness of 65 μm, dried and rolled, and then punched to a predetermined size to prepare a negative electrode.
(리튬 이차전지의 제조)(Manufacture of Lithium Secondary Battery)
음극에 대한 대극으로 리튬 금속 포일을 사용하였다.Lithium metal foil was used as a counter electrode for the negative electrode.
상기 리튬 금속 포일과 음극 사이에 폴리올레핀 세퍼레이터를 개재시킨 후, 에틸렌 카보네이트(EC) 및 디에틸 카보네이트(DEC)를 30:70의 부피비로 혼합한 용매에 1M LiPF6가 용해된 전해질을 주입하여 코인형 리튬 이차전지를 제조하였다. After interposing a polyolefin separator between the lithium metal foil and the negative electrode, an electrolyte containing 1 M LiPF 6 dissolved in a solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a volume ratio of 30:70 was injected to form a coin. A lithium secondary battery was prepared.
실시예 5Example 5
음극 활물질로 실시예 1에서 제조된 음극 활물질 대신 실시예 2에서 제조된 음극활물질을 사용한 것을 제외하고는, 실시예 4와 동일한 방법을 수행하여 리튬 이차전지를 제조하였다.A lithium secondary battery was manufactured in the same manner as in Example 4, except that the negative electrode active material prepared in Example 2 was used instead of the negative electrode active material prepared in Example 1 as the negative electrode active material.
실시예 6Example 6
음극 활물질로 실시예 1에서 제조된 음극 활물질 대신 실시예 3에서 제조된 음극활물질을 사용한 것을 제외하고는, 실시예 4와 동일한 방법을 수행하여 리튬 이차전지를 제조하였다.A lithium secondary battery was manufactured in the same manner as in Example 4, except that the anode active material prepared in Example 3 was used instead of the anode active material prepared in Example 1 as the anode active material.
비교예 4Comparative Example 4
음극 활물질로 비교예 1에서 제조된 음극 활물질을 사용한 것을 제외하고는, 실시예 4와 마찬가지의 방법을 수행하여 리튬 이차전지를 제조하였다.A lithium secondary battery was manufactured in the same manner as in Example 4, except that the negative electrode active material prepared in Comparative Example 1 was used as the negative electrode active material.
비교예 5Comparative Example 5
음극 활물질로 비교예 2에서 제조된 음극 활물질을 사용한 것을 제외하고는, 비교예 4와 마찬가지의 방법을 수행하여 리튬 이차전지를 제조하였다.A lithium secondary battery was manufactured by the same method as Comparative Example 4, except that the negative electrode active material prepared in Comparative Example 2 was used as the negative electrode active material.
비교예 6Comparative Example 6
음극 활물질로 비교예 3에서 제조된 음극 활물질을 사용한 것을 제외하고는, 비교예 4와 마찬가지의 방법을 수행하여 리튬 이차전지를 제조하였다.A lithium secondary battery was manufactured by the same method as Comparative Example 4, except that the negative electrode active material prepared in Comparative Example 3 was used as the negative electrode active material.
실험예Experimental Example
실험예 1: 음극 활물질의 물성 측정Experimental Example 1 Measurement of Physical Properties of Anode Active Material
실시예 1 내지 3 및 비교예 1 내지 3에서 제조된 음극 활물질에 대해 ELTRA社의 CS-800 장비를 이용하여 산소 분석을 진행하였으며, BEL JAPAN社의 BELSORP-max 장비를 이용하여 비표면적 측정을 진행하였다. 또한 Bruker社의 D4 Endeavor XRD 장비를 통해 실시예 1 내지 3의 음극활물질 내에 존재하는 규소 결정립 크기와 비교예 1 내지 3의 음극활물질 내에 존재하는 규소 결정립 크기를 측정하였다. 그 결과를 표 1에 나타내었다.Oxygen analysis was performed on the negative electrode active materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3 using the CS-800 equipment of ELTRA, and the specific surface area was measured using the BELSORP-max equipment of BEL JAPAN. It was. In addition, the silicon grain size present in the negative electrode active materials of Examples 1 to 3 and the silicon grain size present in the negative electrode active materials of Comparative Examples 1 to 3 were measured through Bruker's D4 Endeavor XRD equipment. The results are shown in Table 1.
Figure PCTKR2016014452-appb-T000001
Figure PCTKR2016014452-appb-T000001
상기 표 1에 표기된 바와 같이, 초음파 분쇄하여 제조한 비정질 규소 입자를 포함하는 실시예 1 내지 3의 음극 활물질에서는 산소 원소가 검출되지 않은 반면, 벌크(bulk) 규소 분말을 볼밀 공정으로 분쇄한 규소 입자를 포함하는 비교예 1 내지 3의 음극 활물질에서는 약 5% 이상의 산소 원소가 검출되었다.As shown in Table 1, in the negative electrode active material of Examples 1 to 3 including amorphous silicon particles prepared by ultrasonic pulverization, no oxygen element was detected, while silicon particles pulverized bulk silicon powder by a ball mill process. About 5% or more of oxygen elements were detected in the negative electrode active materials of Comparative Examples 1 to 3 containing.
한편, 음극활물질 내에 포함되는 규소 결정립 크기가 작은 경우, 전극 부피 팽창률이 낮은 것으로 알려져 있다. 이때, 상용 제품인 벌크 규소 분말을 볼밀 공정으로 분쇄한 규소 입자를 포함하는 비교예 1 내지 3의 음극활물질의 경우, 벌크 규소 분말이 가지고 있는 규소 결정립 크기에 따라 분쇄 후에도 상기 표 1에 나타낸 바와 같이, 약 17nm 내지 19nm 크기의 규소 결정립을 포함한다. 반면에, 초음파 분쇄하여 제조된 비정질 규소 입자를 포함하는 실시예 1 내지 3의 음극활물질의 경우, 비교예 1 내지 3의 음극활물질과 비교하여 현저히 낮은, 4.3 nm 이하의 규소 결정립을 포함한다. 따라서, 본 발명의 실시예 1 내지 3의 음극활물질을 포함하는 전극의 경우, 부피 팽창률이 저감된다는 것을 예측할 수 있다.On the other hand, when the silicon grain size contained in the negative electrode active material is small, it is known that the electrode volume expansion rate is low. At this time, in the case of the negative electrode active material of Comparative Examples 1 to 3 including silicon particles obtained by grinding a commercially available bulk silicon powder by a ball mill process, as shown in Table 1 after grinding according to the silicon grain size of the bulk silicon powder, Silicon grains of about 17 nm to 19 nm in size. On the other hand, in the case of the negative electrode active material of Examples 1 to 3 including amorphous silicon particles prepared by ultrasonic grinding, compared to the negative electrode active material of Comparative Examples 1 to 3, the silicon grains of 4.3 nm or less are included. Therefore, in the case of the electrode including the negative electrode active material of Examples 1 to 3 of the present invention, it can be predicted that the volume expansion ratio is reduced.
실험예 2: 리튬 이차전지의 초기 효율 및 충방전 용량 측정Experimental Example 2: Measurement of initial efficiency and charge / discharge capacity of lithium secondary battery
실시예 4 내지 6 및 비교예 4 내지 6에서 제조된 리튬 이차전지(코인형 반쪽 전지)를 정전류/정전압(CC/CV) 조건에서 0.1C의 정전류(CC)로 5mV가 될 때까지 충전한 후 0.005C의 전류에 도달할 때까지 정전압(CV)으로 충전하여 1 사이클째의 충전 용량을 측정하였다. 이후, 20분간 방치한 다음 계속하여 0.1C의 정전류로 1.5V까지 방전하여 초기 효율 및 방전 용량을 측정하였다. 실시예 4 내지 6 및 비교예 4 내지 6의 리튬 이차 전지에 대한 충방전 결과를 하기 표 2에 나타내었다.After charging the lithium secondary battery (coin-type half-cell) prepared in Examples 4 to 6 and Comparative Examples 4 to 6 with a constant current (CC) of 0.1C at constant current / constant voltage (CC / CV) until 5mV The charge capacity of the 1st cycle was measured by charging with constant voltage (CV) until the electric current of 0.005 C was reached. Thereafter, the mixture was left for 20 minutes and then discharged to 1.5 V at a constant current of 0.1 C to measure initial efficiency and discharge capacity. The charging and discharging results of the lithium secondary batteries of Examples 4 to 6 and Comparative Examples 4 to 6 are shown in Table 2 below.
Figure PCTKR2016014452-appb-T000002
Figure PCTKR2016014452-appb-T000002
상기 표 2에 나타낸 바와 같이, 실시예 4의 이차전지가 비교예 4의 이차전지에 비해 초기 효율이 10%, 방전 용량이 약 210 mAh/g 증가하였다. 또한, 실시예 5의 이차전지가 비교예 5의 이차전지에 비해 초기 효율이 9%, 방전 용량이 약 210 mAh/g 증가하였다. 또한, 실시예 6의 이차전지가 비교예 6의 이차전지에 비해 초기 효율이 9%, 방전 용량이 약 80 mAh/g 증가하였다.As shown in Table 2, the secondary battery of Example 4 increased the initial efficiency by 10% and the discharge capacity by about 210 mAh / g, compared to the secondary battery of Comparative Example 4. In addition, compared with the secondary battery of Comparative Example 5, the secondary battery of Example 5 had an initial efficiency of 9% and a discharge capacity of about 210 mAh / g. In addition, compared with the secondary battery of Comparative Example 6, the secondary battery of Example 6 increased the initial efficiency by 9% and the discharge capacity by about 80 mAh / g.
즉, 벌크 규소 분말을 분쇄하여 제조된 규소 입자를 포함하는 비교예 4 내지 6의 음극활물질은 분쇄 과정에서 마찰열 등에 의해 산화가 발생하게 되고, 규소 입자에 산소가 결합되면서 초기 충전 시 비가역상(충전 시에는 생성되나 방전 시에 다시 분해되지 않는 비가역 반응에 의해 형성되는 상)이 형성되기 때문에 초기효율이 낮아질 뿐만 아니라, 가역 반응에 참여할 수 있는 규소 원자의 양이 감소하게 된다. 따라서, 상기 표 2에 나타낸 바와 같이 비교예 1 내지 3의 음극활물질을 포함하는 비교예 4 내지 6의 이차전지의 충방전 가역 용량은 감소된다.That is, the negative electrode active materials of Comparative Examples 4 to 6 including silicon particles prepared by pulverizing the bulk silicon powder are oxidized by frictional heat during grinding, and irreversible phase during initial charging as oxygen is bonded to the silicon particles. Since a phase formed by an irreversible reaction, which is produced during the discharge but is not decomposed again during discharge, is formed, the initial efficiency is lowered and the amount of silicon atoms that can participate in the reversible reaction is reduced. Therefore, as shown in Table 2, the charge and discharge reversible capacity of the secondary batteries of Comparative Examples 4 to 6 including the negative electrode active materials of Comparative Examples 1 to 3 is reduced.
한편, 실시예 6의 이차전지의 경우, 음극활물질 내에서 비정질 규소 입자(111)의 함량이 비교예 4 및 5의 이차전지에 비하여 낮기 때문에, 상대적으로 충방전 용량이 감소하는 것을 알 수 있다.On the other hand, in the secondary battery of Example 6, since the content of the amorphous silicon particles 111 in the negative electrode active material is lower than the secondary batteries of Comparative Examples 4 and 5, it can be seen that the charge and discharge capacity is relatively reduced.
실험예 3: 리튬 이차전지의 수명 특성 및 전극 두께 팽창 특성Experimental Example 3: Lifetime Characteristics and Electrode Thickness Expansion Characteristics of a Lithium Secondary Battery
실시예 4 내지 6 및 비교예 4 내지 6에서 제조된 리튬 이차전지(코인형 반쪽 전지)를 정전류/정전압(CC/CV) 조건에서 0.1C의 정전류(CC)로 5mV가 될 때까지 충전한 후 0.005C의 전류에 도달할 때까지 정전압(CV)으로 충전하여 1 사이클째의 충전 용량을 측정하였다. 이후, 20분간 방치한 다음 계속하여 0.1C의 정전류로 1.5V까지 방전하여 초기 효율 및 방전 용량을 측정하였다. 이후 20분간 방치한 다음, 상기와 동일한 전압 범위 내에서 0.5C 정전류/정전압(CC/CV) 충전 후, 0.5C 정전류(CC) 방전하는 사이클을 50회 반복하여 수명 특성을 측정하였다. 사이클 50회 반복 후 다시 0.5C로 충전하고 코인형 리튬 이차 전지를 분해하여 완전 충전 상태의 음극 두께 팽창률을 측정하였다. 수명 특성 및 전극 두께 팽창 결과를 하기 표 3에 나타내었다.After charging the lithium secondary battery (coin-type half-cell) prepared in Examples 4 to 6 and Comparative Examples 4 to 6 with a constant current (CC) of 0.1C at constant current / constant voltage (CC / CV) until 5mV The charge capacity of the 1st cycle was measured by charging with constant voltage (CV) until the electric current of 0.005 C was reached. Thereafter, the mixture was left for 20 minutes and then discharged to 1.5 V at a constant current of 0.1 C to measure initial efficiency and discharge capacity. Thereafter, after 20 minutes, 0.5C constant current (CC / CV) charging in the same voltage range, and then repeated 0.5C constant current (CC) cycle 50 times to measure the life characteristics. After 50 cycles, the battery was charged at 0.5C again and the coin-type lithium secondary battery was disassembled to measure the negative electrode thickness expansion rate in a fully charged state. The life characteristics and electrode thickness expansion results are shown in Table 3 below.
- 수명 특성(%): 50번째 사이클 방전용량 ÷ 1번째 사이클 방전용량 × 100 전극 두께-Life characteristics (%): 50th cycle discharge capacity ÷ 1st cycle discharge capacity × 100 electrode thickness
- 전극 두께 팽창률(%): (51번째 사이클 충전 음극 두께 - 전지 조립 전 초기 음극 두께) ÷ (전지 조립 전 초기 음극 두께 - 집전체 두께) × 100 -Electrode thickness expansion rate (%): (51th cycle charge negative electrode thickness-initial negative electrode thickness before battery assembly) ÷ (initial negative electrode thickness before battery assembly-current collector thickness) × 100
Figure PCTKR2016014452-appb-T000003
Figure PCTKR2016014452-appb-T000003
상기 표 3에 나타낸 바와 같이, 본 발명의 실시예 4의 이차전지의 경우 수명 특성이 비교예 4의 이차 전지 수명 특성에 비해 약 8% 가량 우수함을 확인할 수 있다. 또한, 본 발명의 실시예 5의 이차전지의 경우 수명 특성이 비교예 5의 이차 전지 수명 특성에 비해 약 9% 가량 우수함을 확인할 수 있다. 또한, 본 발명의 실시예 6의 이차전지의 경우 수명 특성이 비교예 6의 이차 전지 수명 특성에 비해 약 6% 가량 우수함을 확인할 수 있다.As shown in Table 3, in the case of the secondary battery of Example 4 of the present invention it can be seen that the life characteristics are about 8% superior to the secondary battery life characteristics of Comparative Example 4. In addition, it can be seen that the life characteristics of the secondary battery of Example 5 of the present invention are about 9% superior to those of the secondary battery of Comparative Example 5. In addition, it can be seen that the life characteristics of the secondary battery of Example 6 of the present invention are about 6% superior to those of the secondary battery of Comparative Example 6.
또한, 실시예 4 내지 6의 이차 전지의 51번째 사이클 충전 상태의 전극 두께 팽창률이 비교예 4 내지 6의 이차전지 각각에 비해 현저히 낮음을 확인할 수 있다.In addition, it can be seen that the electrode thickness expansion ratio of the 51st cycle charged state of the secondary batteries of Examples 4 to 6 is significantly lower than that of each of the secondary batteries of Comparative Examples 4 to 6.
한편, 실시예 4 및 5의 이차전지의 경우, 음극활물질 내에서 비정질 규소 입자(1, 11)의 함량이 비교예 6의 이차전지에 비하여 높기 때문에, 수명 특성이 높고, 전극 두께 팽창률 또한 높은 것으로 확인된다. 즉, 비교예 6의 이차전지는 규소 입자와 결정질 탄소를 포함하는 음극활물질을 포함하고 있기 때문에, 실시예 4 및 5의 이차전지에 비하여, 수명 특성이 높고, 팽창률이 낮다. On the other hand, in the secondary batteries of Examples 4 and 5, since the content of the amorphous silicon particles (1, 11) in the negative electrode active material is higher than that of the secondary battery of Comparative Example 6, the life characteristics are high and the electrode thickness expansion rate is also high It is confirmed. That is, since the secondary battery of Comparative Example 6 contains a negative electrode active material containing silicon particles and crystalline carbon, compared with the secondary batteries of Examples 4 and 5, the life characteristics are high and the expansion rate is low.

Claims (30)

  1. 실란(SiH4) 가스를 소스로 사용하는 화학기상증착법(CVD)으로 유기 기판 표면에 비정질 규소층을 증착하는 단계(S1);Depositing an amorphous silicon layer on the surface of the organic substrate by chemical vapor deposition (CVD) using a silane (SiH 4 ) gas as a source (S1);
    상기 비정질 규소층을 초음파 분쇄하여 비정질 규소입자를 제조하는 단계(S2);Ultrasonically grinding the amorphous silicon layer to prepare amorphous silicon particles (S2);
    상기 비정질 규소입자를 탄소계 전구체 용액에 분산시켜 분산 용액을 제조하는 단계(S3); Dispersing the amorphous silicon particles in a carbon-based precursor solution to prepare a dispersion solution (S3);
    상기 분산 용액을 분무 건조하여 규소계 복합 전구체를 제조하는 단계(S4); 및Spray drying the dispersion solution to prepare a silicon-based composite precursor (S4); And
    상기 규소계 복합 전구체를 열처리하여, 내부에 1 이상의 비정질 규소입자를 포함하는 비정질 탄소 코팅층을 포함하는 규소계 복합체를 형성하는 단계(S5);를 포함하는 것인 리튬 이차전지용 음극활물질의 제조 방법.Heat-treating the silicon-based composite precursor to form a silicon-based composite including an amorphous carbon coating layer including at least one amorphous silicon particle therein (S5); manufacturing method of a negative electrode active material for a lithium secondary battery.
  2. 청구항 1에 있어서,The method according to claim 1,
    상기 비정질 규소층 증착 단계(S1)는 500℃ 내지 700℃의 온도 및 10-8 Torr 내지 760 Torr의 압력 조건하에서 실란 가스를 10 sccm/60min 내지 50 sccm/60min의 속도로 가하면서 실시하는 것인 리튬 이차전지용 음극활물질의 제조 방법.The amorphous silicon layer deposition step (S1) is carried out while applying the silane gas at a rate of 10 sccm / 60min to 50 sccm / 60min under a temperature of 500 ° C to 700 ° C and a pressure condition of 10 -8 Torr to 760 Torr. Method for producing a negative electrode active material for a lithium secondary battery.
  3. 청구항 1에 있어서,The method according to claim 1,
    상기 증착된 비정질 규소층의 두께는 20nm 내지 500nm 인 것인 리튬 이차전지용 음극활물질의 제조 방법.The thickness of the deposited amorphous silicon layer is 20nm to 500nm manufacturing method of the negative electrode active material for a lithium secondary battery.
  4. 청구항 1에 있어서,The method according to claim 1,
    상기 비정질 규소층 분쇄 단계(S2)는 아세톤 용액에 비정질 규소층이 증착된 유리 기판을 침지한 다음, 초음파 분쇄기를 이용하여 50W 내지 200W의 출력으로 상온에서 10분 내지 20분 동안 초음파 분쇄를 실시하는 것인 리튬 이차전지용 음극활물질의 제조 방법.In the amorphous silicon layer grinding step (S2), the glass substrate on which the amorphous silicon layer is deposited is immersed in an acetone solution, and then subjected to ultrasonic grinding for 10 to 20 minutes at room temperature with an output of 50 W to 200 W using an ultrasonic mill. Method for producing a negative electrode active material for a lithium secondary battery.
  5. 청구항 1에 있어서,The method according to claim 1,
    상기 방법은 비정질 규소입자 제조 단계(S2) 후, 분산 용액 제조 단계(S3) 전에 아세톤 용매를 휘발시켜 분쇄된 비정질 규소입자를 포집하는 단계를 추가로 포함하는 것인 리튬 이차전지용 음극활물질의 제조 방법.The method further includes the step of collecting the pulverized amorphous silicon particles by volatilizing the acetone solvent after the amorphous silicon particle manufacturing step (S2), before the dispersion solution manufacturing step (S3). .
  6. 청구항 1에 있어서,The method according to claim 1,
    상기 분쇄된 비정질 규소입자의 평균입경(D50)은 5nm 내지 500nm인 것인 리튬 이차전지용 음극활물질의 제조 방법.The average particle diameter (D50) of the pulverized amorphous silicon particles is 5nm to 500nm manufacturing method of the negative electrode active material for a lithium secondary battery.
  7. 청구항 1에 있어서,The method according to claim 1,
    상기 분산 용액 제조 단계(S3)는 증류수에, 1000℃ 이하의 온도에서 탄화 가능한 탄소계 물질을 혼합하여 탄소계 전구체 용액을 제조한 다음, 비정질 규소 입자를 분산시켜 수행되는 것인 리튬 이차전지용 음극활물질의 제조 방법.The dispersing solution manufacturing step (S3) is to prepare a carbon-based precursor solution by mixing a carbonizable carbon-based material in distilled water, at a temperature of 1000 ℃ or less, and then to disperse amorphous silicon particles to the lithium secondary battery negative electrode active material Method of preparation.
  8. 청구항 7에 있어서,The method according to claim 7,
    상기 탄소계 물질은 수크로오스, 글루코오스, 프룩토오스, 갈락토오스, 말토오스, 및 락토오스로 이루어진 군으로부터 선택된 단일물 또는 2종 이상의 혼합물인 것인 리튬 이차전지용 음극활물질의 제조 방법.The carbonaceous material is a single material or a mixture of two or more selected from the group consisting of sucrose, glucose, fructose, galactose, maltose, and lactose, a method for producing a negative electrode active material for a lithium secondary battery.
  9. 청구항 1에 있어서,The method according to claim 1,
    상기 탄소계 전구체 용액은 비정질 규소 입자 100 중량부에 대하여 25 중량부 내지 4,000 중량부를 사용하는 것인 리튬 이차전지용 음극활물질의 제조 방법.The carbon-based precursor solution is 25 to 4,000 parts by weight based on 100 parts by weight of the amorphous silicon particles to prepare a negative electrode active material for a lithium secondary battery.
  10. 청구항 1에 있어서,The method according to claim 1,
    상기 비정질 규소입자 분산 시에, 결정질 및 비정질 탄소로 이루어진 군으로부터 선택된 적어도 하나 이상의 전도성 탄소계 물질을 추가로 분산하는 것인 리튬 이차전지용 음극활물질의 제조 방법.At the time of dispersing the amorphous silicon particles, at least one conductive carbon-based material selected from the group consisting of crystalline and amorphous carbon further dispersing a negative electrode active material for a lithium secondary battery.
  11. 청구항 10에 있어서,The method according to claim 10,
    상기 전도성 탄소계 물질은 비정질 규소 입자 100 중량부에 대하여 0.99 중량부 내지 1,900 중량부로 분산하는 것인 리튬 이차전지용 음극활물질의 제조방법.The conductive carbon-based material is dispersed in 0.99 part by weight to 1,900 parts by weight based on 100 parts by weight of amorphous silicon particles.
  12. 청구항 1에 있어서,The method according to claim 1,
    상기 분산 용액을 분무 건조하는 단계(S4)는 상기 전구체 용액을 분무 장치 내로 공급하여 분무에 의해 액적을 형성한 후, 상기 액적을 건조하는 단계가 동시에 수행되는 것인 리튬 이차전지용 음극활물질의 제조방법.The spray drying step (S4) of the dispersion solution is to supply the precursor solution into a spray device to form a droplet by spraying, and then drying the droplet is a method of manufacturing a negative electrode active material for a lithium secondary battery .
  13. 청구항 1에 있어서,The method according to claim 1,
    상기 분무 건조 단계는 약 50℃ 내지 300℃에서 10 mL/min 내지 50 mL/min의 속도로 실시하는 것인 리튬 이차전지용 음극활물질의 제조방법.The spray drying step is a method for producing a negative electrode active material for a lithium secondary battery that is carried out at a rate of 10 mL / min to 50 mL / min at about 50 ℃ to 300 ℃.
  14. 청구항 1에 있어서,The method according to claim 1,
    상기 규소계 복합 전구체를 열처리하는 단계(S5)는 400℃ 내지 1000℃ 온도에서, 약 10분 내지 1시간 동안 실시하는 것인 리튬 이차전지용 음극활물질의 제조방법.The step (S5) of the heat treatment of the silicon-based composite precursor is performed for about 10 minutes to 1 hour at 400 ℃ to 1000 ℃ temperature method for producing a negative electrode active material for a lithium secondary battery.
  15. 청구항 1의 방법에 의해 제조된 리튬 이차전지용 음극활물질로서,As a negative electrode active material for a lithium secondary battery produced by the method of claim 1,
    비정질 탄소 코팅층; 및Amorphous carbon coating layer; And
    상기 비정질 탄소 코팅층 내부에 포함된 1 이상의 비정질 규소입자로 이루어진 규소 복합체를 포함하는 것인 리튬 이차전지용 음극활물질.A negative electrode active material for a lithium secondary battery comprising a silicon composite made of one or more amorphous silicon particles contained in the amorphous carbon coating layer.
  16. 청구항 15에 있어서,The method according to claim 15,
    상기 비정질 규소입자는 단일 입자 또는 상기 단일 입자로 이루어진 1차 비정질 규소입자가 응집되어 형성된 2차 비정질 규소입자를 포함하는 것인 리튬 이차전지용 음극활물질.The amorphous silicon particle is a negative electrode active material for a lithium secondary battery comprising a single particle or secondary amorphous silicon particles formed by agglomeration of primary amorphous silicon particles consisting of the single particle.
  17. 청구항 15에 있어서,The method according to claim 15,
    상기 비정질 규소입자는 비정질 탄소 코팅층 내부에 균일하게 분산되어 있는 것인 리튬 이차전지용 음극 활물질. The amorphous silicon particles are uniformly dispersed in the amorphous carbon coating layer negative electrode active material for a lithium secondary battery.
  18. 청구항 15에 있어서,The method according to claim 15,
    상기 비정질 규소입자는 음극활물질 전체 중량에 대하여 1 내지 95 중량%로 포함되는 것인 리튬 이차전지용 음극 활물질. The amorphous silicon particles are contained in 1 to 95% by weight based on the total weight of the negative electrode active material negative electrode active material for a lithium secondary battery.
  19. 청구항 15에 있어서,The method according to claim 15,
    상기 비정질 규소입자 : 비정질 탄소 코팅층의 중량비는 1:99 내지 95:5인 것인 리튬 이차전지용 음극 활물질. The amorphous silicon particle: the weight ratio of the amorphous carbon coating layer is 1:99 to 95: 5 negative electrode active material for a lithium secondary battery.
  20. 청구항 19에 있어서,The method according to claim 19,
    상기 비정질 규소입자 : 비정질 탄소 코팅층의 중량비는 5:95 내지 90:10인 것인 리튬 이차전지용 음극 활물질. The weight ratio of the amorphous silicon particles: amorphous carbon coating layer is 5:95 to 90:10, the negative electrode active material for a lithium secondary battery.
  21. 청구항 15에 있어서,The method according to claim 15,
    상기 음극활물질은 비정질 탄소 코팅층 내부에 결정질 탄소 및 비정질 탄소로 이루어진 군으로부터 선택된 적어도 하나 이상의 전도성 탄소계 물질을 추가로 포함하는 것인 리튬 이차전지용 음극 활물질. The negative electrode active material further comprises at least one conductive carbon-based material selected from the group consisting of crystalline carbon and amorphous carbon inside the amorphous carbon coating layer.
  22. 청구항 21에 있어서,The method according to claim 21,
    상기 음극활물질은 비정질 탄소 코팅층; 및 상기 비정질 탄소 코팅층 내부에 포함된 1 이상의 비정질 규소입자 및 비정질 탄소를 포함하는 규소 복합체를 포함하는 것인 리튬 이차전지용 음극 활물질. The negative electrode active material is an amorphous carbon coating layer; And a silicon composite including at least one amorphous silicon particle and amorphous carbon included in the amorphous carbon coating layer.
  23. 청구항 22에 있어서,The method according to claim 22,
    상기 비정질 탄소는 음극활물질 전체 중량을 기준으로 0.1 중량% 내지 50 중량%로 포함되는 것인 리튬 이차전지용 음극 활물질. The amorphous carbon is a negative active material for a lithium secondary battery that is contained in 0.1 to 50% by weight based on the total weight of the negative electrode active material.
  24. 청구항 21에 있어서,The method according to claim 21,
    상기 음극활물질은 비정질 탄소 코팅층; 및 상기 비정질 탄소 코팅층 내부에 포함된 1 이상의 비정질 규소입자 및 결정질 탄소를 포함하며, 상기 1 이상의 비정질 규소 입자는 결정질 탄소 표면에 분포되어 있는 것인 리튬 이차전지용 음극 활물질. The negative electrode active material is an amorphous carbon coating layer; And one or more amorphous silicon particles and crystalline carbon contained in the amorphous carbon coating layer, wherein the one or more amorphous silicon particles are distributed on the surface of the crystalline carbon.
  25. 청구항 24에 있어서,The method of claim 24,
    상기 결정질 탄소의 평균입경(D50)은 300nm 내지 30㎛인 것인 리튬 이차전지용 음극활물질.The average particle diameter (D50) of the crystalline carbon is 300nm to 30㎛ negative electrode active material for a lithium secondary battery.
  26. 청구항 24에 있어서,The method of claim 24,
    상기 결정질 탄소는 음극활물질 전체 중량을 기준으로 10 중량% 내지 90 중량%로 포함되는 것인 리튬 이차전지용 음극 활물질. The crystalline carbon is 10% by weight to 90% by weight based on the total weight of the negative electrode active material negative electrode active material for a lithium secondary battery.
  27. 청구항 15에 있어서,The method according to claim 15,
    상기 음극활물질의 평균입경(D50)은 50㎚ 내지 35㎛인 것인 리튬 이차전지용 음극 활물질.An average particle diameter (D50) of the negative electrode active material is a lithium secondary battery negative electrode active material is 50nm to 35㎛.
  28. 청구항 15에 있어서,The method according to claim 15,
    상기 음극활물질의 비표면적(BET)은 0.5㎡/g 내지 20㎡/g인 것인 리튬 이차전지용 음극활물질. Specific surface area (BET) of the negative electrode active material is 0.5 m 2 / g to 20 m 2 / g negative electrode active material for a lithium secondary battery.
  29. 집전체, 및Current collector, and
    상기 집전체의 적어도 일면에 형성된 청구항 15의 음극 활물질을 포함하는 것인 음극.A negative electrode comprising the negative electrode active material of claim 15 formed on at least one surface of the current collector.
  30. 양극, 음극, 상기 양극 및 음극 사이에 개재된 세퍼레이터, 및 비수성 전해액을 포함하며, 상기 음극은 청구항 29의 음극인 것인 리튬 이차전지.Lithium secondary battery comprising a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte, the negative electrode is the negative electrode of claim 29.
PCT/KR2016/014452 2015-12-10 2016-12-09 Method for preparing anode active material for lithium secondary battery and lithium secondary battery to which method is applied WO2017099523A1 (en)

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