WO2017222113A1 - Negative electrode active material for lithium secondary battery, method for manufacturing same, and lithium secondary battery including same - Google Patents

Negative electrode active material for lithium secondary battery, method for manufacturing same, and lithium secondary battery including same Download PDF

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Publication number
WO2017222113A1
WO2017222113A1 PCT/KR2016/011754 KR2016011754W WO2017222113A1 WO 2017222113 A1 WO2017222113 A1 WO 2017222113A1 KR 2016011754 W KR2016011754 W KR 2016011754W WO 2017222113 A1 WO2017222113 A1 WO 2017222113A1
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negative electrode
active material
electrode active
secondary battery
lithium secondary
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PCT/KR2016/011754
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French (fr)
Korean (ko)
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도의송
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삼성에스디아이 주식회사
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Publication of WO2017222113A1 publication Critical patent/WO2017222113A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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 negative electrode active material for a lithium secondary battery, a method of manufacturing the same, and a lithium secondary battery including the same.
  • Lithium secondary batteries which are in the spotlight as power sources of recent portable small electronic devices, use organic electrolytes and exhibit a discharge voltage that is two times higher than that of a battery using an alkaline aqueous solution. As a result, the lithium secondary battery has a high energy density.
  • Such a lithium secondary battery includes a positive electrode including a positive electrode active material capable of intercalation and deintercalation of lithium, and a negative electrode active material capable of intercalating and deintercalating lithium. It is used by injecting electrolyte into a battery cell containing a negative electrode.
  • the negative electrode active material has recently been actively researched using metal materials such as Si-based materials such as Si and Si-metal alloys.
  • Si-based materials are irreversible due to sustained side reactions with the electrolyte, and the basic framework of the material is broken due to expansion and contraction during charge and discharge.
  • an organic film or a carbon coating film may be formed on the surface of the Si-based material, but in this case, durability of the coating film is reduced due to continuous charging and discharging, thereby lowering various reliability such as conductivity of the material.
  • One embodiment is to provide a negative active material for a lithium secondary battery having improved conductivity and excellent life characteristics.
  • Another embodiment is to provide a method of manufacturing the negative electrode active material for the lithium secondary battery.
  • Another embodiment is to provide a lithium secondary battery including the negative electrode active material for the lithium secondary battery.
  • One embodiment includes a core particle comprising a silicon-based alloy; Carbon nanoparticles attached to the surface of the core particles; A coating layer surrounding the core particles to which the carbon nanoparticles are attached and including amorphous carbon; And a conductive material positioned on the surface of the coating layer, at least some of the conductive material is located inside the coating layer, the carbon nanoparticles are the same as or different from the amorphous carbon, and the conductive material is the carbon nanoparticles and It provides a negative electrode active material for a lithium secondary battery different from the amorphous carbon.
  • the conductive material may include carbon nanotubes, carbon nanofibers, natural graphite, artificial graphite, graphene, carbon black, or a combination thereof.
  • At least some of the conductive material may be located inside the coating layer to contact the core particles.
  • At least some of the conductive material may be located inside the core particles.
  • the conductive material may have a length of 6 ⁇ m to 12 ⁇ m.
  • the content of the conductive material may be 0.5 wt% to 2.0 wt% with respect to the total amount of the negative active material.
  • the average particle diameter of the carbon nanoparticles may be 1/10 or less than the average particle diameter of the core particles.
  • the carbon nanoparticles may include amorphous carbon particles having an average particle diameter of 1 nm to 100 nm.
  • the silicon-based alloy may be represented by the following formula (1).
  • the M is iron (Fe), copper (Cu), magnesium (Mg), chromium (Cr), nickel (Ni), zinc (Zn), manganese (Mn), cobalt (Co), titanium (Ti), germanium ( Ge), calcium (Ca), aluminum (Al), or a combination thereof.
  • the core particle includes an inert matrix including at least one of silicon and Group 2 to 14 metal elements except silicon; And active silicon nanoparticles dispersed in the inert matrix.
  • the content of the active silicon nanoparticles may be 30 atomic% to 50 atomic% with respect to the total atomic weight of the silicon-based alloy.
  • the average particle diameter of the active silicon nanoparticles may be 1 nm to 100 nm.
  • the thickness of the coating layer may be 0.1 ⁇ m to 10 ⁇ m.
  • Another embodiment of the present invention provides a method of manufacturing a semiconductor device, the method comprising: obtaining a first particle by mixing a core particle including a silicon-based alloy and carbon nanoparticles; Mixing the first particles, the amorphous carbon precursor, and the conductive material to obtain second particles; And heat treating the second particles, wherein the carbon nanoparticles are the same as or different from the amorphous carbon precursor, and the conductive material is different from the carbon nanoparticles and the amorphous carbon precursor.
  • Another embodiment provides a lithium secondary battery including a negative electrode including the negative electrode active material.
  • FIG. 1 is a schematic view showing the configuration of a negative electrode active material according to an embodiment.
  • FIG. 2 is a schematic view showing a rechargeable lithium battery according to one embodiment.
  • FIG. 3 is an X-ray diffraction (XRD) analysis graph of the silicon-based alloy prepared in Example 1.
  • XRD X-ray diffraction
  • FIG. 4 is a field emission scanning electron microscope (FE-SEM) photograph of the anode active material according to Example 1.
  • FIG. 4 is a field emission scanning electron microscope (FE-SEM) photograph of the anode active material according to Example 1.
  • FIG. 5 is a field emission scanning electron microscope (FE-SEM) photograph of the negative electrode active material according to Comparative Example 1.
  • FIG. 5 is a field emission scanning electron microscope (FE-SEM) photograph of the negative electrode active material according to Comparative Example 1.
  • FIG. 6 is a field emission scanning electron microscope (FE-SEM) photograph of the negative electrode active material according to Comparative Example 2.
  • FIG. 6 is a field emission scanning electron microscope (FE-SEM) photograph of the negative electrode active material according to Comparative Example 2.
  • Example 7 is a graph showing the life characteristics of the lithium secondary battery according to Example 1 and Comparative Example 2.
  • FIG. 1 is only an example presented to help understand the structure of the negative electrode active material according to one embodiment, but the present invention is not limited thereto.
  • FIG. 1 is a schematic view showing the configuration of a negative electrode active material according to an embodiment.
  • the anode active material 10 for a lithium secondary battery includes a core particle including a silicon-based alloy, carbon nanoparticles 13 attached to a surface of the core particle, and the carbon nanoparticles on a surface thereof. It may include a coating layer 14 surrounding the attached core particles, and a conductive material 15 located on the surface of the coating layer.
  • the core particle may have a structure including an inactive matrix 11 and active silicon nanoparticles 12 dispersed in the inactive matrix 11.
  • the core particle may be formed of a silicon-based alloy.
  • the silicon-based alloy may include at least 50% by weight of silicon (Si), for example, at least 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, and at least 90% by weight of silicon. (Si) may be included.
  • the silicon-based alloy may be represented by the following formula (1).
  • M may include at least one of Groups 2 to 14 metal elements except silicon.
  • M is, for example, iron (Fe), copper (Cu), magnesium (Mg), chromium (Cr), nickel (Ni), zinc (Zn), manganese (Mn), cobalt (Co), titanium (Ti) , Germanium (Ge), calcium (Ca), aluminum (Al) or a combination thereof.
  • the inactive matrix 11 may include at least one of silicon and a group 2 to 14 metal element except silicon.
  • the silicon constituting the silicon-based alloy may be divided into active silicon and inactive silicon, and the active silicon may be reversibly reacted with lithium ions, and thus is directly related to the capacity of the silicon-based alloy. Together with forming a non-active matrix structure that does not react with lithium ions serves to suppress the volume expansion of the silicon-based alloy.
  • the active silicon is precipitated and dispersed as nanoparticles in this inactive matrix.
  • the active silicon nanoparticles may be crystalline or amorphous.
  • the content of the active silicon nanoparticles 12 may be 30 atomic% to 50 atomic% with respect to the total atomic weight of the silicon-based alloy.
  • the content of the active silicon nanoparticles is within the above range, it is possible to effectively suppress the volume expansion of the silicon-based alloy during charging and discharging of the electrode using the same, the capacity characteristics of the electrode can be excellent.
  • the average particle diameter of the active silicon nanoparticles 12 may be 1 nm to 100 nm, for example, 10 nm to 100 nm.
  • the average particle diameter of the active silicon nanoparticles 12 is a Scherrer's equation using the half width of the peak of the Si (111) plane in the X-ray diffraction (XRD) spectrum using CuK ⁇ characteristic X-ray wavelength 1.541 ⁇ .
  • the inert silicon forms a binary alloy phase together with Group 2 to Group 14 metal elements, which are other metal components, to form the inactive matrix 11.
  • the inactive matrix 11 is represented by Si 2 M (wherein M comprises at least one selected from Fe, Cu, Mg, Cr, Ni, Zn, Mn, Co, Ti, Ge, Ca and Al). It may comprise a binary alloy phase.
  • the inactive matrix 11 may include, for example, Si 2 Fe.
  • the core particles may be prepared by a method of high energy ball mill, melt spinning, or the like.
  • the core particles may have an average particle diameter of 0.5 ⁇ m to 10 ⁇ m, for example, 1 ⁇ m to 10 ⁇ m, 1 ⁇ m to 5 ⁇ m, and 2.5 ⁇ m to 5 ⁇ m.
  • the average particle diameter refers to a particle size corresponding to 50% from the smallest particle, that is, D50 when the total particle number is 100% in a distribution curve accumulated in order from the smallest particle size to the largest particle size.
  • the D50 may be measured by a particle size analyzer, a TEM or SEM photograph, or a measuring device using dynamic light scattering.
  • Carbon nanoparticles 13 may be attached to the surface of the core particles.
  • the average particle diameter of the carbon nanoparticles 13 may be 1/10 or less than the average particle diameter of the core particles, for example, may be 1/1000 to 1/10, 1/100 to 1/50. When the average particle diameter of the carbon nanoparticles 13 is within the above range, electrons may be smoothly transferred to the core particles to improve electrical conductivity of the negative electrode active material, thereby improving life characteristics of the lithium secondary battery.
  • the carbon nanoparticles 13 may be amorphous.
  • the average particle diameter of the carbon nanoparticles may be, for example, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 30 nm, or 1 nm to 10 nm.
  • the carbon nanoparticles 13 are mainly materials remaining after processing crude oil and coal, and are powders in which substantial amounts of organic substances have been removed through several purification.
  • the carbon nanoparticles may include, for example, carbon black obtained by vaporizing crude oil, natural gas, acetylene gas, etc. at 1600 ° C to 2000 ° C.
  • the carbon nanoparticles 13 may be in the form of plate, sphere, fiber, or powder, and the like, and the shape thereof is not particularly limited.
  • the content of the carbon nanoparticles 13 may be 0.1 parts by weight to 5.0 parts by weight based on 100 parts by weight of the core particles, for example, 0.5 parts by weight to 2.0 parts by weight.
  • the content of the carbon nanoparticles is within the range, as the electrical conductivity of the negative electrode active material is improved, the life characteristics of the lithium secondary battery may be improved.
  • the coating layer 14 surrounding the core particles having the carbon nanoparticles attached to the surface may include amorphous carbon.
  • amorphous carbon examples include soft carbon, hard carbon, mesophase pitch carbide, calcined coke, and the like, and these may be used alone or in combination of two or more thereof.
  • the amount of the amorphous carbon may be 1 wt% to 30 wt% with respect to the total amount of the negative electrode active material, for example, 5 wt% to 25 wt%.
  • the content of the amorphous carbon is within the above range, it may not reduce the battery capacity while providing a sufficient conductive path between the negative electrode active material particles.
  • the thickness of the coating layer may be 10 nm to 10 ⁇ m, for example, 10 nm to 1.0 ⁇ m, 20 nm to 150 nm, or 35 nm to 100 nm, but is not limited thereto. When the thickness of the coating layer is within the above range, it may not reduce battery capacity while providing a sufficient conductive path between the negative electrode active material particles.
  • the conductive material 15 may be located on the surface of the coating layer surrounding the core particles to which the carbon nanoparticles are attached. Specifically, the conductive material 15 may be located at least a portion of the inside of the coating layer 14, for example, at least a portion of the length of the conductive material 15 of the coating layer 14 It may be located inside and in contact with the core particles. In addition, for example, at least a part of the length of the conductive material 15 may be located even inside the core particles. In this way, the conductive material is added to the negative electrode active material in a structure in which the conductive material is located inside the coating layer, further in contact with the core particles located in the coating layer, or even in the structure of the core particles. It is possible to maintain the (path) to improve the conductivity of the negative electrode active material, thereby contributing to increase the efficiency and life characteristics of the lithium secondary battery.
  • the conductive material 15 may be a material different from the amorphous carbon forming the carbon nanoparticles 13 and the coating layer 14.
  • the conductive material 15 may include carbon nanotubes, carbon nanofibers, natural graphite, artificial graphite, graphene, carbon black, or a combination thereof.
  • the conductive material may have a length of 6 ⁇ m to 12 ⁇ m. When the length of the conductive material is within the range, it is easy to form a structure embedded in the coating layer, thereby further improving the electrical conductivity.
  • the content of the conductive material may be 0.5% to 2.0% by weight based on the total amount of the negative electrode active material.
  • the electrical conductivity of the negative electrode active material may be improved to implement a lithium secondary battery having excellent life characteristics.
  • the first particles having a structure in which the carbon nanoparticles are attached to the surface of the core particles can be obtained.
  • the first particles, the amorphous carbon precursor, and the conductive material are mixed to obtain second particles.
  • a negative electrode active material having a structure in which a surface of the first particles is surrounded by a coating layer of amorphous carbon and at least a portion of the conductive material is positioned inside the coating layer may be manufactured.
  • the amorphous carbon precursors are sucrose, sucrose, methylene diphenyl diisocyanate, polyurethane, phenol resin, naphthalene resin, polyvinyl alcohol, polyvinyl chloride, furfuryl alcohol, and polyacrylo, respectively.
  • Nitrile, polyamide, furan resin, cellulose, styrene, polyimide, epoxy resin, vinyl chloride resin, coal pitch, petroleum pitch, mesoface pitch, tar, low molecular weight heavy oil, or a combination thereof can be used.
  • the coating method is not particularly limited when forming the coating layer of amorphous carbon, and for example, a dry coating method, a liquid coating method, or the like may be used.
  • a dry coating method may be vapor deposition, chemical vapor deposition (CVD), or the like.
  • the liquid coating may include impregnation and spraying.
  • the heat treatment may be carried out at a temperature of 500 °C to 700 °C in an inert atmosphere, for example, may be carried out at 500 °C to 600 °C.
  • the heat treatment is performed within the above temperature range, it is possible to sufficiently secure the content of the active silicon, to remove impurities during the carbonization process, thereby reducing the irreversible capacity may improve the charge and discharge characteristics.
  • FIG. 2 is a schematic view showing a rechargeable lithium battery according to one embodiment.
  • a lithium secondary battery according to one embodiment is described as an example of a cylindrical shape, the present invention is not limited thereto, and may be applied to various types of batteries, such as a square battery, a coin type, and a pouch type.
  • a lithium secondary battery 100 includes a cathode 114, a cathode 112 facing the cathode 114, and a separator disposed between the anode 114 and the anode 112.
  • a sealing member 140 for sealing 120 for sealing 120.
  • the negative electrode 112 includes a current collector and a negative electrode active material layer formed on the current collector.
  • the current collector may be copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam (foam), copper foam, a polymer substrate coated with a conductive metal, or a combination thereof, but is not limited thereto.
  • the negative electrode active material layer may include a negative electrode active material, and may further include a binder and a conductive material.
  • the negative electrode active material is as described above.
  • the binder adheres the negative electrode active material particles to each other well, and also serves to adhere the negative electrode active material to the current collector, and representative examples thereof include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, and carboxylated.
  • Polyvinylchloride, polyvinylfluoride, ethylene oxide containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene- Butadiene rubber, epoxy resin, nylon and the like can be used, but are not limited thereto.
  • the conductive material is used to impart conductivity to the electrode, and any battery can be used as long as it is an electronic conductive material without causing chemical change in the battery.
  • any battery can be used as long as it is an electronic conductive material without causing chemical change in the battery.
  • natural graphite, artificial graphite, graphene, carbon black, acetylene Carbon-based materials such as black, ketjen black, and carbon fiber Metal materials such as metal powder or metal fibers such as copper, nickel, aluminum and silver; Conductive polymers such as polyphenylene derivatives; Or a conductive material containing a mixture thereof.
  • the positive electrode 114 includes a current collector and a positive electrode active material layer formed on the current collector.
  • the cathode active material layer may include a cathode active material, and may further include a binder and a conductive material.
  • Al aluminum
  • Al aluminum
  • the current collector but is not limited thereto.
  • a compound (lithiated intercalation compound) capable of reversible intercalation and deintercalation of lithium may be used.
  • one or more of complex oxides of metal and lithium of cobalt, manganese, nickel or a combination thereof may be used, and specific examples thereof may be a compound represented by one of the following formulas:
  • Li a A 1 - b B b D 2 ( in the above formula, 0.90 ⁇ a ⁇ 1.8, and 0 ⁇ b ⁇ 0.5); Li a E 1 -b B b 0 2-c D c (wherein 0.90 ⁇ a ⁇ 1.8, 0 ⁇ b ⁇ 0.5, 0 ⁇ c ⁇ 0.05); LiE 2-b B b 0 4-c D c (wherein 0 ⁇ b ⁇ 0.5, 0 ⁇ c ⁇ 0.05); Li a Ni 1 -b - c Co b B c D ⁇ (wherein 0.90 ⁇ a ⁇ 1.8, 0 ⁇ b ⁇ 0.5, 0 ⁇ c ⁇ 0.05, and 0 ⁇ ⁇ 2); Li a Ni 1 -b- c Co b B c O 2 - ⁇ F ⁇ ( wherein, 0.90 ⁇ a ⁇ 1.8, 0 ⁇ b ⁇ 0.5,
  • A is Ni, Co, Mn or a combination thereof
  • B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or combinations thereof
  • D is O, F, S, P, or a combination thereof
  • E is Co, Mn or a combination thereof
  • F is F, S, P or a combination thereof
  • G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof
  • Q is Ti, Mo, Mn or a combination thereof
  • I is Cr, V, Fe, Sc, Y or a combination thereof
  • J may be V, Cr, Mn, Co, Ni, Cu or a combination thereof.
  • the binder adheres positively to the positive electrode active material particles, and also serves to adhere the positive electrode active material to the positive electrode current collector, and specific examples thereof include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, and polyvinyl chloride. , Carboxylated polyvinylchloride, polyvinylfluoride, ethylene oxide containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, Acrylated styrene-butadiene rubber, epoxy resin, nylon, and the like, but are not limited thereto.
  • the conductive material is used to impart conductivity to the electrode, and any battery can be used as long as it is an electronic conductive material without causing chemical change in the battery.
  • natural graphite, artificial graphite, graphene, carbon black, acetylene Metal powders, such as black, Ketjen black, carbon fiber, copper, nickel, aluminum, silver, metal fiber, etc. can be used, and 1 type (s) or 1 or more types can be mixed and conductive materials, such as a polyphenylene derivative, can be used. .
  • the positive electrode and the negative electrode are prepared by mixing an active material, a conductive material, and a binder in a solvent to prepare an active material composition, and applying the composition to a current collector.
  • N-methylpyrrolidone may be used as the solvent, and water may be used when an aqueous binder is used as the binder, but is not limited thereto. Since such an electrode manufacturing method is well known in the art, detailed description thereof will be omitted.
  • the electrolyte solution contains an organic solvent and a lithium salt.
  • the organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move.
  • the organic solvent may be selected from carbonate, ester, ether, ketone, alcohol, and the like.
  • Examples of the carbonate solvent include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), and ethylpropyl carbonate ( Ethylpropyl carbonate (EPC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) and the like may be used.
  • DMC dimethyl carbonate
  • DEC diethyl carbonate
  • DPC dipropyl carbonate
  • MPC methylpropyl carbonate
  • EPC ethylpropyl carbonate
  • EMC ethylmethyl carbonate
  • EMC ethylmethyl carbonate
  • EC ethylene carbonate
  • PC propylene carbonate
  • BC butylene carbonate
  • the chain carbonate compound and the cyclic carbonate compound when a mixture of the chain carbonate compound and the cyclic carbonate compound is used, it can be prepared with a solvent having a high viscosity and a low viscosity.
  • the cyclic carbonate compound and the chain carbonate compound may be mixed and used in a volume ratio of about 1: 1 to 1: 9.
  • ester solvent is, for example, methyl acetate, ethyl acetate, n-propyl acetate, methyl propionate, ethyl propionate, ⁇ -butyrolactone, decanolide, valerolactone, mevalonolactone (mevalonolactone), caprolactone and the like can be used.
  • ether solvent for example, dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, etc.
  • ketone solvent cyclohexanone may be used. have.
  • ethyl alcohol, isopropyl alcohol, etc. may be used as the alcohol solvent.
  • the organic solvent may be used singly or in mixture of one or more, and the mixing ratio in the case of mixing one or more may be appropriately adjusted according to the desired battery performance.
  • the electrolyte solution may further include an additive such as an overcharge inhibitor such as ethylene carbonate and pyrocarbonate.
  • an overcharge inhibitor such as ethylene carbonate and pyrocarbonate.
  • the lithium salt is a substance that dissolves in an organic solvent and acts as a source of lithium ions in the battery to enable operation of a basic lithium secondary battery and to promote the movement of lithium ions between the positive electrode and the negative electrode.
  • lithium salt examples include LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiN (SO 3 C 2 F 5 ) 2 , LiN (CF 3 SO 2 ) 2 , LiC 4 F 9 SO 3 , LiClO 4 , LiAlO 2 , LiAlCl 4 , LiN (C x F 2x + 1 SO 2 ) (C y F 2y + 1 SO 2 ), where x and y are natural numbers, LiCl, LiI, LiB (C 2 O 4 ) 2 (lithium And bisoxalato borate (LiBOB), or a combination thereof.
  • LiPF 6 LiBF 4 , LiSbF 6 , LiAsF 6 , LiN (SO 3 C 2 F 5 ) 2 , LiN (CF 3 SO 2 ) 2 , LiC 4 F 9 SO 3 , LiClO 4 , LiAlO 2 , LiAlCl 4 , LiN (C x F 2x
  • the concentration of the lithium salt is preferably used within the range of about 0.1M to about 2.0M.
  • concentration of the lithium salt is included in the above range, since the electrolyte has an appropriate conductivity and viscosity, it can exhibit excellent electrolyte performance, and lithium ions can move effectively.
  • the separator 113 separates the negative electrode from the positive electrode and provides a passage for moving lithium ions, and any separator can be used as long as it is commonly used in a lithium battery. In other words, those having low resistance to ion migration of the electrolyte and excellent electrolyte-wetting ability can be used.
  • it is selected from glass fiber, polyester, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or a combination thereof, and may be in a nonwoven or woven form.
  • a polyolefin-based polymer separator such as polyethylene or polypropylene is mainly used for a lithium ion battery, and a coated separator including a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength. Can be used as a structure.
  • carbon black having 100 parts by weight of FeS i2 powder and an average particle diameter of 3 nm
  • FeSi 2 powder having carbon black attached to the surface was prepared using a powder coating machine (mechanofusion). Subsequently, 89.0% by weight of FeS i2 powder, 10.0% by weight of coal tar, and 1.0% by weight of carbon nanotubes having a 6 ⁇ m length, were carbon-mixed on the surface by a ball mill method in a dry method, and then at 500 ° C. under a nitrogen atmosphere. Heat treatment was performed to prepare a negative electrode active material having a carbon coating layer having a thickness of 1 ⁇ m on the surface of the FeSi 2 powder.
  • a negative electrode active material was prepared in the same manner as in Example 1, except that 89.5% by weight of FeSi 2 powder, 10.0% by weight of coal tar, and 0.5% by weight of carbon nanotubes were mixed and heat treated with carbon black.
  • a negative electrode active material was prepared in the same manner as in Example 1, except that 88.0% by weight of FeSi 2 powder, 10.0% by weight of coal tar, and 2.0% by weight of carbon nanotubes were mixed with carbon black.
  • FeSi 2 powder having carbon black prepared in Example 1 attached to the surface was used as a negative electrode active material.
  • Example 1 90.0% by weight of the FeSi2 powder and coal tar pitch 10.0% by weight of the carbon black prepared in Example 1 were mixed by a ball mill method of a dry method, and then heat-treated at 500 ° C. under a nitrogen atmosphere to the surface of the FeSi 2 powder.
  • Slurry was prepared by mixing 97% by weight of the negative electrode active material prepared in Examples 1 to 3 and Comparative Examples 1 to 3, 1.5% by weight of carboxymethylcellulose and 1.5% by weight of styrene-butadiene rubber in distilled water. The slurry was applied to Cu foil, dried and rolled to prepare a negative electrode.
  • LiCoO 2 LiCoO 2
  • PVdF polyvinylidene fluoride
  • carbon black 1.3% by weight
  • a lithium secondary battery was manufactured using the negative electrode and the positive electrode, a polyethylene separator, and an electrolyte solution. At this time, 1.1 M of LiPF 6 was dissolved in an organic solvent in which ethylene carbonate (EC), diethyl carbonate (DEC) and fluoroethylene carbonate (FEC) were mixed in a volume ratio of 3: 3: 4.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • FEC fluoroethylene carbonate
  • XRD analysis conditions were CuK ⁇ characteristic X-ray wavelength of 1.541 kHz.
  • FIG. 3 is an X-ray diffraction (XRD) analysis graph of the silicon-based alloy prepared in Example 1.
  • XRD X-ray diffraction
  • the silicon-based alloy prepared in Example 1 only Si 2 Fe phase appeared as an inactive phase, and 40 atomic% Si which did not form an inactive matrix appeared as an active phase. That is, it can be seen that the silicon-based alloy of Example 1 is composed of 60 atomic% and 40 atomic% of Si 2 Fe which is an inactive phase and Si which is an active phase, respectively. In this case, it can be seen that the average particle diameter of the active phase Si is 100 nm or less.
  • 4 to 6 are field emission scanning electron microscope (FE-SEM) photographs of the negative electrode active materials according to Example 1, Comparative Example 1, and Comparative Example 2, respectively. 4 to 6, it can be seen that the negative electrode active material of Example 1 has a structure in which a coating layer of amorphous carbon is formed on a surface of a silicon-based alloy particle and a conductive material is positioned inside the coating layer. On the other hand, the negative electrode active material of Comparative Example 1 did not have an amorphous carbon coating layer, it can be seen that the negative electrode active material of Comparative Example 2 does not have a conductive material.
  • FE-SEM field emission scanning electron microscope
  • the capacity retention rate is calculated by the following equation.
  • Capacity retention rate (%) (discharge capacity in each cycle / discharge capacity in the first cycle) X 100
  • Example 1 using a negative active material having a structure in which a coating layer of amorphous carbon surrounds a silicon-based alloy on which carbon nanoparticles are attached to a surface and at least a portion of the conductive material is disposed in the coating layer, compared to Comparative Example 2 It can be seen that the life characteristics are excellent. From this, it can be seen that the negative electrode active material having the above structure improves the life characteristics of the lithium secondary battery by improving electrical conductivity.

Abstract

Provided are a negative electrode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery including the same, the negative electrode active material comprising: a core particle including a silicone-based alloy; a carbon nanoparticle attached to the surface of the core particle; a coating layer, which surrounds the core particle having the carbon nanoparticle attached to the surface thereof and includes amorphous carbon; and a conductive material positioned on the surface of the coating layer, wherein at least a part of the conductive material is positioned inside the coating layer.

Description

리튬 이차 전지용 음극 활물질, 이의 제조 방법 및 이를 포함하는 리튬 이차 전지Anode active material for lithium secondary battery, preparation method thereof and lithium secondary battery comprising same
리튬 이차 전지용 음극 활물질, 이의 제조 방법 및 이를 포함하는 리튬 이차 전지에 관한 것이다. The present invention relates to a negative electrode active material for a lithium secondary battery, a method of manufacturing the same, and a lithium secondary battery including the same.
최근의 휴대용 소형 전자기기의 전원으로서 각광받고 있는 리튬 이차 전지는 유기 전해액을 사용함에 따라, 기존의 알칼리 수용액을 사용한 전지보다 2배 이상의 높은 방전 전압을 나타내며, 그 결과 높은 에너지 밀도를 나타내는 전지이다.BACKGROUND ART Lithium secondary batteries, which are in the spotlight as power sources of recent portable small electronic devices, use organic electrolytes and exhibit a discharge voltage that is two times higher than that of a battery using an alkaline aqueous solution. As a result, the lithium secondary battery has a high energy density.
이러한 리튬 이차 전지는 리튬을 인터칼레이션(intercalation) 및 디인터칼레이션(deintercalation) 할 수 있는 양극 활물질을 포함하는 양극, 그리고 리튬을 인터칼레이션 및 디인터칼레이션할 수 있는 음극 활물질을 포함하는 음극을 포함하는 전지 셀에 전해액을 주입하여 사용된다.Such a lithium secondary battery includes a positive electrode including a positive electrode active material capable of intercalation and deintercalation of lithium, and a negative electrode active material capable of intercalating and deintercalating lithium. It is used by injecting electrolyte into a battery cell containing a negative electrode.
상기 음극 활물질로는 최근 전지의 고용량화를 달성하기 위해 금속계 재료, 예를 들어, Si, Si-금속 합금 등의 Si계 재료를 사용한 연구가 활발히 진행되고 있다. 그러나 Si계 재료는 전해액과의 지속되는 부반응으로 인해 비가역성이 증가하고, 충방전시 팽창 수축으로 인해 재료의 기본 틀이 깨져 가게 된다.In order to achieve high capacity of a battery, the negative electrode active material has recently been actively researched using metal materials such as Si-based materials such as Si and Si-metal alloys. However, Si-based materials are irreversible due to sustained side reactions with the electrolyte, and the basic framework of the material is broken due to expansion and contraction during charge and discharge.
이를 방지하게 위해, Si계 재료의 표면에 유기막 또는 카본 코팅막을 형성하기도 하나, 이 경우에도 지속적인 충방전으로 인해 코팅막의 내구성이 감소하여 재료의 전도성 등 여러 가지 신뢰성을 저하시킨다.In order to prevent this, an organic film or a carbon coating film may be formed on the surface of the Si-based material, but in this case, durability of the coating film is reduced due to continuous charging and discharging, thereby lowering various reliability such as conductivity of the material.
일 구현예는 전도성이 향상되어 수명 특성이 우수한 리튬 이차 전지용 음극 활물질을 제공하기 위한 것이다.One embodiment is to provide a negative active material for a lithium secondary battery having improved conductivity and excellent life characteristics.
다른 일 구현예는 상기 리튬 이차 전지용 음극 활물질의 제조 방법을 제공하기 위한 것이다.Another embodiment is to provide a method of manufacturing the negative electrode active material for the lithium secondary battery.
또 다른 일 구현예는 상기 리튬 이차 전지용 음극 활물질을 포함하는 리튬 이차 전지를 제공하기 위한 것이다.Another embodiment is to provide a lithium secondary battery including the negative electrode active material for the lithium secondary battery.
일 구현예는 실리콘계 합금을 포함하는 코어 입자; 상기 코어 입자의 표면에 부착된 탄소 나노 입자; 상기 탄소 나노 입자가 표면에 부착된 코어 입자를 둘러싸고 비정질 탄소를 포함하는 코팅층; 및 상기 코팅층의 표면에 위치하는 도전재를 포함하고, 상기 도전재 중 적어도 일부는 상기 코팅층의 내부에 위치하고, 상기 탄소 나노 입자는 상기 비정질 탄소와 동일하거나 상이하고, 상기 도전재는 상기 탄소 나노 입자 및 상기 비정질 탄소와 상이한 리튬 이차 전지용 음극 활물질을 제공한다.One embodiment includes a core particle comprising a silicon-based alloy; Carbon nanoparticles attached to the surface of the core particles; A coating layer surrounding the core particles to which the carbon nanoparticles are attached and including amorphous carbon; And a conductive material positioned on the surface of the coating layer, at least some of the conductive material is located inside the coating layer, the carbon nanoparticles are the same as or different from the amorphous carbon, and the conductive material is the carbon nanoparticles and It provides a negative electrode active material for a lithium secondary battery different from the amorphous carbon.
상기 도전재는 탄소 나노 튜브, 탄소 나노 섬유, 천연흑연, 인조흑연, 그래핀, 카본 블랙, 또는 이들의 조합을 포함할 수 있다. The conductive material may include carbon nanotubes, carbon nanofibers, natural graphite, artificial graphite, graphene, carbon black, or a combination thereof.
상기 도전재 중 적어도 일부는 상기 코팅층의 내부에 위치하여 상기 코어 입자와 접촉할 수 있다.At least some of the conductive material may be located inside the coating layer to contact the core particles.
상기 도전재 중 적어도 일부는 상기 코어 입자의 내부에 위치할 수 있다.At least some of the conductive material may be located inside the core particles.
상기 도전재의 길이는 6㎛ 내지 12㎛일 수 있다. The conductive material may have a length of 6 μm to 12 μm.
상기 도전재의 함량은 상기 음극 활물질의 총량에 대하여 0.5 중량% 내지 2.0 중량%일 수 있다. The content of the conductive material may be 0.5 wt% to 2.0 wt% with respect to the total amount of the negative active material.
상기 탄소 나노 입자의 평균입경은 상기 코어 입자의 평균입경 대비 1/10 이하일 수 있다.The average particle diameter of the carbon nanoparticles may be 1/10 or less than the average particle diameter of the core particles.
상기 탄소 나노 입자는 1 nm 내지 100 nm의 평균입경을 가지는 비정질 탄소 입자를 포함할 수 있다.The carbon nanoparticles may include amorphous carbon particles having an average particle diameter of 1 nm to 100 nm.
상기 실리콘계 합금은 하기 화학식 1로 표시될 수 있다.The silicon-based alloy may be represented by the following formula (1).
[화학식 1][Formula 1]
SiaMb Si a M b
(상기 화학식 1에서, M은 실리콘을 제외한 2족 내지 14족 금속원소 중 적어도 하나를 포함하고, 0.5≤a≤0.9, 0.1≤b≤0.5, 및 a+b=1이다.)(In Formula 1, M includes at least one of Group 2 to Group 14 metal elements except silicon, and 0.5 ≦ a ≦ 0.9, 0.1 ≦ b ≦ 0.5, and a + b = 1.)
상기 M은 철(Fe), 구리(Cu), 마그네슘(Mg), 크롬(Cr), 니켈(Ni), 아연(Zn), 망간(Mn), 코발트(Co), 티타늄(Ti), 게르마늄(Ge), 칼슘(Ca), 알루미늄(Al) 또는 이들의 조합을 포함할 수 있다.The M is iron (Fe), copper (Cu), magnesium (Mg), chromium (Cr), nickel (Ni), zinc (Zn), manganese (Mn), cobalt (Co), titanium (Ti), germanium ( Ge), calcium (Ca), aluminum (Al), or a combination thereof.
상기 코어 입자는 실리콘 및 실리콘을 제외한 2족 내지 14족 금속원소 중 적어도 하나를 포함하는 비활성 매트릭스; 및 상기 비활성 매트릭스 내에 분산된 활성 실리콘 나노 입자를 포함할 수 있다.The core particle includes an inert matrix including at least one of silicon and Group 2 to 14 metal elements except silicon; And active silicon nanoparticles dispersed in the inert matrix.
상기 활성 실리콘 나노 입자의 함량은 상기 실리콘계 합금의 총 원자량에 대하여 30 원자% 내지 50 원자% 일 수 있다.The content of the active silicon nanoparticles may be 30 atomic% to 50 atomic% with respect to the total atomic weight of the silicon-based alloy.
상기 활성 실리콘 나노 입자의 평균입경은 1 nm 내지 100 nm 일 수 있다.The average particle diameter of the active silicon nanoparticles may be 1 nm to 100 nm.
상기 코팅층의 두께는 0.1 ㎛ 내지 10 ㎛ 일 수 있다.The thickness of the coating layer may be 0.1 ㎛ to 10 ㎛.
다른 일 구현예는 실리콘계 합금을 포함하는 코어 입자, 그리고 탄소 나노 입자를 혼합하여 제1 입자를 얻는 단계; 상기 제1 입자, 비정질 탄소 전구체, 그리고 도전재를 혼합하여 제2 입자를 얻는 단계; 및 상기 제2 입자를 열처리하는 단계를 포함하고, 상기 탄소 나노 입자는 상기 비정질 탄소 전구체와 동일하거나 상이하고, 상기 도전재는 상기 탄소 나노 입자 및 상기 비정질 탄소 전구체와 상이한 리튬 이차 전지용 음극 활물질의 제조 방법을 제공한다.Another embodiment of the present invention provides a method of manufacturing a semiconductor device, the method comprising: obtaining a first particle by mixing a core particle including a silicon-based alloy and carbon nanoparticles; Mixing the first particles, the amorphous carbon precursor, and the conductive material to obtain second particles; And heat treating the second particles, wherein the carbon nanoparticles are the same as or different from the amorphous carbon precursor, and the conductive material is different from the carbon nanoparticles and the amorphous carbon precursor. To provide.
또 다른 일 구현예는 상기 음극 활물질을 포함하는 음극을 포함하는 리튬 이차 전지를 제공한다.Another embodiment provides a lithium secondary battery including a negative electrode including the negative electrode active material.
기타 구현예들의 구체적인 사항은 이하의 상세한 설명에 포함되어 있다.Specific details of other embodiments are included in the following detailed description.
음극 활물질의 전도성이 향상됨으로써 수명 특성이 우수한 리튬 이차 전지를 구현할 수 있다.By improving the conductivity of the negative electrode active material, a lithium secondary battery having excellent lifespan characteristics may be implemented.
도 1은 일 구현예에 따른 음극 활물질의 구성을 보여주는 개략도이다.1 is a schematic view showing the configuration of a negative electrode active material according to an embodiment.
도 2는 일 구현예에 따른 리튬 이차 전지를 보여주는 개략도이다.2 is a schematic view showing a rechargeable lithium battery according to one embodiment.
도 3은 실시예 1에서 제조된 실리콘계 합금의 X-선 회절(XRD) 분석 그래프이다.3 is an X-ray diffraction (XRD) analysis graph of the silicon-based alloy prepared in Example 1. FIG.
도 4는 실시예 1에 따른 음극 활물질의 전계방사 주사전자현미경(FE-SEM) 사진이다.4 is a field emission scanning electron microscope (FE-SEM) photograph of the anode active material according to Example 1. FIG.
도 5는 비교예 1에 따른 음극 활물질의 전계방사 주사전자현미경(FE-SEM) 사진이다.5 is a field emission scanning electron microscope (FE-SEM) photograph of the negative electrode active material according to Comparative Example 1. FIG.
도 6은 비교예 2에 따른 음극 활물질의 전계방사 주사전자현미경(FE-SEM) 사진이다.6 is a field emission scanning electron microscope (FE-SEM) photograph of the negative electrode active material according to Comparative Example 2. FIG.
도 7은 실시예 1과 비교예 2에 따른 리튬 이차 전지의 수명 특성을 나타내는 그래프이다.7 is a graph showing the life characteristics of the lithium secondary battery according to Example 1 and Comparative Example 2.
(도면 부호의 설명)(Explanation of reference signs)
10: 음극 활물질10: negative electrode active material
11: 비활성 매트릭스11: inactive matrix
12: 활성 실리콘 나노 입자12: active silicon nanoparticles
13: 탄소 나노 입자13: carbon nanoparticles
14: 코팅층14: coating layer
15: 도전재15: conductive material
100: 리튬 이차 전지100: lithium secondary battery
112: 음극112: cathode
113: 세퍼레이터113: separator
114: 양극114: anode
120: 전지 용기120: battery container
140: 봉입 부재140: sealing member
이하, 본 발명의 구현예를 상세히 설명하기로 한다. 　다만, 이는 예시로서 제시되는 것으로, 이에 의해 본 발명이 제한되지는 않으며 본 발명은 후술할 청구범위의 범주에 의해 정의될 뿐이다. Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.
이하에서는 일 구현예에 따른 리튬 이차 전지용 음극 활물질에 대해 도 1을 참고하여 설명한다. 도 1은 일 구현예에 따른 음극 활물질의 구조에 대한 이해를 돕기 위해 제시한 일 예일 뿐, 본 발명이 이에 한정되는 것은 아니다.Hereinafter, a negative active material for a rechargeable lithium battery according to one embodiment will be described with reference to FIG. 1. 1 is only an example presented to help understand the structure of the negative electrode active material according to one embodiment, but the present invention is not limited thereto.
도 1은 일 구현예에 따른 음극 활물질의 구성을 보여주는 개략도이다.1 is a schematic view showing the configuration of a negative electrode active material according to an embodiment.
도 1을 참고하면, 일 구현예에 따른 리튬 이차 전지용 음극 활물질(10)은 실리콘계 합금을 포함하는 코어 입자, 상기 코어 입자의 표면에 부착된 탄소 나노 입자(13), 상기 탄소 나노 입자가 표면에 부착된 코어 입자를 둘러싸는 코팅층(14), 그리고 상기 코팅층의 표면에 위치하는 도전재(15)를 포함할 수 있다. 상기 코어 입자는 비활성 매트릭스(11), 그리고 상기 비활성 매트릭스(11) 내에 분산된 활성 실리콘 나노 입자(12)를 포함하는 구조를 가질 수 있다.Referring to FIG. 1, the anode active material 10 for a lithium secondary battery according to an embodiment includes a core particle including a silicon-based alloy, carbon nanoparticles 13 attached to a surface of the core particle, and the carbon nanoparticles on a surface thereof. It may include a coating layer 14 surrounding the attached core particles, and a conductive material 15 located on the surface of the coating layer. The core particle may have a structure including an inactive matrix 11 and active silicon nanoparticles 12 dispersed in the inactive matrix 11.
일 예로, 상기 코어 입자는 실리콘계 합금으로 이루어질 수 있다.For example, the core particle may be formed of a silicon-based alloy.
이 때, 상기 실리콘계 합금은 50 중량% 이상의 실리콘(Si)을 포함할 수 있고, 예를 들면, 50 중량% 이상, 60 중량% 이상, 70 중량% 이상, 80 중량% 이상, 90 중량% 이상의 실리콘(Si)을 포함할 수 있다.In this case, the silicon-based alloy may include at least 50% by weight of silicon (Si), for example, at least 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, and at least 90% by weight of silicon. (Si) may be included.
구체적으로, 상기 실리콘계 합금은 하기 화학식 1로 표시될 수 있다.Specifically, the silicon-based alloy may be represented by the following formula (1).
[화학식 1][Formula 1]
SiaMb Si a M b
상기 화학식 1에서, M은 실리콘을 제외한 2족 내지 14족 금속원소 중 적어도 하나를 포함할 수 있다. M은 예를 들면, 철(Fe), 구리(Cu), 마그네슘(Mg), 크롬(Cr), 니켈(Ni), 아연(Zn), 망간(Mn), 코발트(Co), 티타늄(Ti), 게르마늄(Ge), 칼슘(Ca), 알루미늄(Al) 또는 이들의 조합을 포함할 수 있다.In Formula 1, M may include at least one of Groups 2 to 14 metal elements except silicon. M is, for example, iron (Fe), copper (Cu), magnesium (Mg), chromium (Cr), nickel (Ni), zinc (Zn), manganese (Mn), cobalt (Co), titanium (Ti) , Germanium (Ge), calcium (Ca), aluminum (Al) or a combination thereof.
상기 화학식 1에서, 0.5≤a≤0.9, 0.1≤b≤0.5, 그리고 a+b=1 일 수 있다.In Formula 1, 0.5 ≦ a ≦ 0.9, 0.1 ≦ b ≦ 0.5, and a + b = 1.
더욱 구체적으로, 상기 실리콘계 합금은 SiaFeb (여기서, 0.5≤a≤0.9, 0.1≤b≤0.5, 및 a+b=1 임) 일 수 있다.More specifically, the silicon-based alloy may be Si a Fe b (where 0.5 ≦ a ≦ 0.9, 0.1 ≦ b ≦ 0.5, and a + b = 1).
상기 비활성 매트릭스(11)는 실리콘, 그리고 실리콘을 제외한 2족 내지 14족 금속원소 중 적어도 하나를 포함할 수 있다. The inactive matrix 11 may include at least one of silicon and a group 2 to 14 metal element except silicon.
즉, 실리콘계 합금을 구성하는 실리콘은 활성 실리콘 및 비활성 실리콘으로 구분될 수 있으며, 상기 활성 실리콘은 리튬 이온과 가역 반응할 수 있으므로 실리콘계 합금의 용량과 직접적인 관련이 있고, 상기 비활성 실리콘은 상기 금속원소와 함께 리튬 이온과 반응하지 않는 비활성 매트릭스 구조를 형성하면서 실리콘계 합금의 부피 팽창을 억제하는 역할을 한다. 상기 활성 실리콘은 이러한 비활성 매트릭스 내에 나노 입자로 석출되어 분산된다. 상기 활성 실리콘 나노 입자는 결정질 또는 비정질일 수 있다.That is, the silicon constituting the silicon-based alloy may be divided into active silicon and inactive silicon, and the active silicon may be reversibly reacted with lithium ions, and thus is directly related to the capacity of the silicon-based alloy. Together with forming a non-active matrix structure that does not react with lithium ions serves to suppress the volume expansion of the silicon-based alloy. The active silicon is precipitated and dispersed as nanoparticles in this inactive matrix. The active silicon nanoparticles may be crystalline or amorphous.
상기 활성 실리콘 나노 입자(12)의 함량은 상기 실리콘계 합금의 총 원자량에 대하여 30 원자% 내지 50 원자% 일 수 있다. 상기 활성 실리콘 나노 입자의 함량이 상기 범위 내인 경우 이를 이용한 전극의 충방전시 실리콘계 합금의 부피 팽창을 효과적으로 억제할 수 있고, 전극의 용량 특성이 우수하게 나타날 수 있다. The content of the active silicon nanoparticles 12 may be 30 atomic% to 50 atomic% with respect to the total atomic weight of the silicon-based alloy. When the content of the active silicon nanoparticles is within the above range, it is possible to effectively suppress the volume expansion of the silicon-based alloy during charging and discharging of the electrode using the same, the capacity characteristics of the electrode can be excellent.
상기 활성 실리콘 나노 입자(12)의 평균입경은 1 nm 내지 100 nm 일 수 있고, 예를 들면, 10 nm 내지 100 nm 일 수 있다. 상기 범위 내의 평균입경을 가진 활성 실리콘 나노 입자가 비활성 매트릭스 내에 분산됨으로써, 충방전 사이클 동안 활성 실리콘 나노 입자의 부피 팽창이 이를 둘러싼 비활성 매트릭스에 의해 효율적으로 완충될 수 있다. 상기 활성 실리콘 나노 입자(12)의 평균입경은 CuKα 특성 X-선 파장 1.541Å을 이용한 X-선 회절(XRD) 스펙트럼에서, Si(111)면에 대한 피크의 반치폭을 이용하여 쉐러 방정식(Scherrer's equation)으로부터 구할 수 있다.The average particle diameter of the active silicon nanoparticles 12 may be 1 nm to 100 nm, for example, 10 nm to 100 nm. By dispersing the active silicon nanoparticles having an average particle diameter within the above range in the inert matrix, the volume expansion of the active silicon nanoparticles during the charge and discharge cycle can be efficiently buffered by the surrounding inert matrix. The average particle diameter of the active silicon nanoparticles 12 is a Scherrer's equation using the half width of the peak of the Si (111) plane in the X-ray diffraction (XRD) spectrum using CuKα characteristic X-ray wavelength 1.541 Å. Can be obtained from
상기 비활성 실리콘은 다른 금속 성분인 2족 내지 14족 금속원소와 함께 2원계 합금상을 형성하며 비활성 매트릭스(11)를 형성한다. 상기 비활성 매트릭스(11)는 Si2M(여기서, M은 Fe, Cu, Mg, Cr, Ni, Zn, Mn, Co, Ti, Ge, Ca 및 Al으로부터 선택되는 적어도 하나를 포함함)으로 표시되는 2원계 합금상을 포함할 수 있다. 상기 비활성 매트릭스(11)는 예를 들면, Si2Fe를 포함할 수 있다.The inert silicon forms a binary alloy phase together with Group 2 to Group 14 metal elements, which are other metal components, to form the inactive matrix 11. The inactive matrix 11 is represented by Si 2 M (wherein M comprises at least one selected from Fe, Cu, Mg, Cr, Ni, Zn, Mn, Co, Ti, Ge, Ca and Al). It may comprise a binary alloy phase. The inactive matrix 11 may include, for example, Si 2 Fe.
상기 코어 입자는 고에너지 볼밀, 멜트 스피닝 등의 방법으로 제조될 수 있다.The core particles may be prepared by a method of high energy ball mill, melt spinning, or the like.
상기 코어 입자는 평균입경이 0.5 ㎛ 내지 10 ㎛ 일 수 있고, 예를 들면, 1 ㎛ 내지 10 ㎛, 1 ㎛ 내지 5 ㎛, 2.5 ㎛ 내지 5 ㎛ 일 수 있다. 상기 코어 입자의 평균입경이 상기 범위 내인 경우 전해액과의 반응성을 억제하여 사이클 특성의 향상에 기여하며, 또한 음극 슬러리 형성시 분산 안정성을 향상시킬 수 있다. 상기 평균입경은 입자 크기가 가장 작은 입자부터 가장 큰 입자 순서로 누적시킨 분포 곡선에서, 전체 입자 개수를 100%으로 했을 때 가장 작은 입자로부터 50%에 해당되는 입경, 즉, D50을 의미한다. D50은 입도 분석기로 측정하거나, TEM 또는 SEM 사진으로부터 측정할 수도 있으며, 동적광산란법(dynamic Light-scattering)을 이용한 측정장치를 이용할 수도 있다.The core particles may have an average particle diameter of 0.5 μm to 10 μm, for example, 1 μm to 10 μm, 1 μm to 5 μm, and 2.5 μm to 5 μm. When the average particle diameter of the core particles is within the above range, the reactivity with the electrolyte may be suppressed to contribute to the improvement of cycle characteristics, and the dispersion stability may be improved when the negative electrode slurry is formed. The average particle diameter refers to a particle size corresponding to 50% from the smallest particle, that is, D50 when the total particle number is 100% in a distribution curve accumulated in order from the smallest particle size to the largest particle size. The D50 may be measured by a particle size analyzer, a TEM or SEM photograph, or a measuring device using dynamic light scattering.
상기 코어 입자의 표면에는 탄소 나노 입자(13)가 부착될 수 있다. Carbon nanoparticles 13 may be attached to the surface of the core particles.
상기 탄소 나노 입자(13)의 평균입경은 상기 코어 입자의 평균입경 대비 1/10 이하일 수 있고, 예를 들면, 1/1000 내지 1/10, 1/100 내지 1/50 일 수 있다. 상기 탄소 나노 입자(13)의 평균입경이 상기 범위 내인 경우 코어 입자로의 전자 이동이 원활해져 음극 활물질의 전기 전도성을 향상시킬 수 있으며, 이에 의해 리튬 이차 전지의 수명 특성이 향상될 수 있다.The average particle diameter of the carbon nanoparticles 13 may be 1/10 or less than the average particle diameter of the core particles, for example, may be 1/1000 to 1/10, 1/100 to 1/50. When the average particle diameter of the carbon nanoparticles 13 is within the above range, electrons may be smoothly transferred to the core particles to improve electrical conductivity of the negative electrode active material, thereby improving life characteristics of the lithium secondary battery.
상기 탄소 나노 입자(13)는 비정질일 수 있다. 상기 탄소 나노 입자의 크기가 작을수록 더욱 비정질 성향을 띠게 된다. 상기 탄소 나노 입자의 평균 입경은 예컨대, 1 nm 내지 100 nm, 1 nm 내지 50 nm, 1 nm 내지 30 nm, 또는 1 nm 내지 10 nm 일 수 있다. The carbon nanoparticles 13 may be amorphous. The smaller the size of the carbon nanoparticles are more amorphous. The average particle diameter of the carbon nanoparticles may be, for example, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 30 nm, or 1 nm to 10 nm.
구체적으로, 상기 탄소 나노 입자(13)는 주로 원유와 석탄을 가공하고 남은 물질로서, 여러 번의 정제를 거쳐 유기물질을 상당량 제거한 상태의 파우더이다. 상기 탄소 나노 입자는 예를 들어, 원유, 천연가스, 아세틸렌가스 등을 1600℃ 내지 2000℃에서 분사하여 기화시켜 얻어지는 카본 블랙을 포함할 수 있다. Specifically, the carbon nanoparticles 13 are mainly materials remaining after processing crude oil and coal, and are powders in which substantial amounts of organic substances have been removed through several purification. The carbon nanoparticles may include, for example, carbon black obtained by vaporizing crude oil, natural gas, acetylene gas, etc. at 1600 ° C to 2000 ° C.
상기 탄소 나노 입자(13)는 판상, 구상, 섬유상 또는 분말 형태 등일 수 있으며, 형상에 특별히 제한은 없다.The carbon nanoparticles 13 may be in the form of plate, sphere, fiber, or powder, and the like, and the shape thereof is not particularly limited.
상기 탄소 나노 입자(13)의 함량은 상기 코어 입자 100 중량부에 대하여 0.1 중량부 내지 5.0 중량부 일 수 있고, 예를 들면, 0.5 중량부 내지 2.0 중량부 일 수 있다. 상기 탄소 나노 입자의 함량이 상기 범위 내인 경우 음극 활물질의 전기 전도성이 향상됨에 따라 리튬 이차 전지의 수명 특성이 개선될 수 있다. The content of the carbon nanoparticles 13 may be 0.1 parts by weight to 5.0 parts by weight based on 100 parts by weight of the core particles, for example, 0.5 parts by weight to 2.0 parts by weight. When the content of the carbon nanoparticles is within the range, as the electrical conductivity of the negative electrode active material is improved, the life characteristics of the lithium secondary battery may be improved.
탄소 나노 입자가 표면에 부착된 코어 입자를 둘러싸는 상기 코팅층(14)은 비정질 탄소를 포함할 수 있다.The coating layer 14 surrounding the core particles having the carbon nanoparticles attached to the surface may include amorphous carbon.
상기 비정질 탄소는 소프트 카본, 하드 카본, 메조페이스 피치 탄화물, 소성된 코크스 등을 들 수 있고, 이들을 단독으로 또는 2종 이상 혼합하여 사용할 수 있다.Examples of the amorphous carbon include soft carbon, hard carbon, mesophase pitch carbide, calcined coke, and the like, and these may be used alone or in combination of two or more thereof.
상기 비정질 탄소의 함량은 상기 음극 활물질의 총량에 대하여 1 중량% 내지 30 중량% 일 수 있고, 예를 들면, 5 중량% 내지 25 중량% 일 수 있다. 상기 비정질 탄소의 함량이 상기 범위 내인 경우 음극 활물질 입자들 사이에 충분한 도전 통로를 제공하면서 전지 용량을 저하시키지 않을 수 있다.The amount of the amorphous carbon may be 1 wt% to 30 wt% with respect to the total amount of the negative electrode active material, for example, 5 wt% to 25 wt%. When the content of the amorphous carbon is within the above range, it may not reduce the battery capacity while providing a sufficient conductive path between the negative electrode active material particles.
상기 코팅층의 두께는 10 nm 내지 10 ㎛ 일 수 있고, 예를 들면, 10 nm 내지 1.0 ㎛, 20 nm 내지 150 nm, 또는 35 nm 내지 100 nm일 수 있으나, 이에 한정되는 것은 아니다. 상기 코팅층의 두께가 상기 범위 내인 경우 음극 활물질 입자들 사이에 충분한 도전 통로를 제공하면서 전지 용량을 저하시키지 않을 수 있다. The thickness of the coating layer may be 10 nm to 10 μm, for example, 10 nm to 1.0 μm, 20 nm to 150 nm, or 35 nm to 100 nm, but is not limited thereto. When the thickness of the coating layer is within the above range, it may not reduce battery capacity while providing a sufficient conductive path between the negative electrode active material particles.
일 구현예에 따르면, 탄소 나노 입자가 표면에 부착된 코어 입자를 둘러싸는 코팅층의 표면에 도전재(15)가 위치할 수 있다. 구체적으로, 상기 도전재(15)는 그 중 적어도 일부가 상기 코팅층(14)의 내부에 위치할 수 있고, 예를 들면, 상기 도전재(15)의 길이 중 적어도 일부가 상기 코팅층(14)의 내부에 위치하여 상기 코어 입자와 접촉할 수도 있다. 또한 예를 들면, 상기 도전재(15)의 길이 중 적어도 일부가 상기 코어 입자의 내부에까지 위치하여 있을 수 있다. 이와 같이, 도전재가 코팅층 내부에 위치하여 있는 구조로, 나아가 코팅층 내부에 위치하는 코어 입자와 접촉하는 구조, 또는 더 나아가 코어 입자의 내부에까지 위치하는 구조로 음극 활물질에 첨가됨으로써, 실리콘계 합금 간의 도전 경로(path)를 유지할 수 있어 음극 활물질의 전도성을 향상시키며, 이에 따라 리튬 이차 전지의 효율 증가 및 수명 특성 향상에 기여할 수 있다. According to one embodiment, the conductive material 15 may be located on the surface of the coating layer surrounding the core particles to which the carbon nanoparticles are attached. Specifically, the conductive material 15 may be located at least a portion of the inside of the coating layer 14, for example, at least a portion of the length of the conductive material 15 of the coating layer 14 It may be located inside and in contact with the core particles. In addition, for example, at least a part of the length of the conductive material 15 may be located even inside the core particles. In this way, the conductive material is added to the negative electrode active material in a structure in which the conductive material is located inside the coating layer, further in contact with the core particles located in the coating layer, or even in the structure of the core particles. It is possible to maintain the (path) to improve the conductivity of the negative electrode active material, thereby contributing to increase the efficiency and life characteristics of the lithium secondary battery.
상기 도전재(15)는 상기 탄소 나노 입자(13)와 상기 코팅층(14)을 이루는 상기 비정질 탄소와 상이한 물질일 수 있다. 구체적으로, 상기 도전재(15)는 탄소 나노 튜브, 탄소 나노 섬유, 천연흑연, 인조흑연, 그래핀, 카본 블랙, 또는 이들의 조합을 포함할 수 있다.The conductive material 15 may be a material different from the amorphous carbon forming the carbon nanoparticles 13 and the coating layer 14. Specifically, the conductive material 15 may include carbon nanotubes, carbon nanofibers, natural graphite, artificial graphite, graphene, carbon black, or a combination thereof.
상기 도전재의 길이는 6㎛ 내지 12㎛ 일 수 있다. 상기 도전재의 길이가 상기 범위 내인 경우 상기 코팅층 내부로 박힌 구조의 형성이 용이하며, 이에 따라 전기 전도성을 더욱 향상시킬 수 있다. The conductive material may have a length of 6 μm to 12 μm. When the length of the conductive material is within the range, it is easy to form a structure embedded in the coating layer, thereby further improving the electrical conductivity.
상기 도전재의 함량은 상기 음극 활물질의 총량에 대하여 0.5 중량% 내지 2.0 중량 %일 수 있다. 상기 도전재의 함량이 상기 범위 내인 경우 음극 활물질의 전기 전도성이 향상되어 우수한 수명 특성을 가지는 리튬 이차 전지를 구현할 수 있다. The content of the conductive material may be 0.5% to 2.0% by weight based on the total amount of the negative electrode active material. When the content of the conductive material is within the above range, the electrical conductivity of the negative electrode active material may be improved to implement a lithium secondary battery having excellent life characteristics.
이하, 다른 일 구현예에 따른 상기 음극 활물질의 제조 방법에 대해 설명한다.Hereinafter, a method of manufacturing the negative active material according to another embodiment will be described.
실리콘계 합금을 포함하는 코어 입자, 그리고 탄소 나노 입자를 혼합함으로써, 상기 코어 입자의 표면에 상기 탄소 나노 입자가 부착된 구조를 가지는 제1 입자를 얻을 수 있다. 이어서, 상기 제1 입자, 비정질 탄소 전구체, 그리고 도전재를 혼합하여 제2 입자를 얻는다. 이어서, 상기 제2 입자를 열처리함으로써, 상기 제1 입자의 표면이 비정질 탄소의 코팅층으로 둘러싸이고 상기 코팅층의 내부에 도전재중 적어도 일부가 위치하는 구조를 가지는 음극 활물질을 제조할 수 있다.By mixing the core particles containing the silicon-based alloy and the carbon nanoparticles, the first particles having a structure in which the carbon nanoparticles are attached to the surface of the core particles can be obtained. Next, the first particles, the amorphous carbon precursor, and the conductive material are mixed to obtain second particles. Subsequently, by heat-treating the second particles, a negative electrode active material having a structure in which a surface of the first particles is surrounded by a coating layer of amorphous carbon and at least a portion of the conductive material is positioned inside the coating layer may be manufactured.
상기 비정질 탄소 전구체는 각각 수크로오스(sucrose), 메틸렌 디페닐 디이소시아네이트(methylene diphenyl diisocyanate), 폴리 우레탄, 페놀 수지, 나프탈렌 수지, 폴리비닐알코올, 폴리비닐클로라이드, 퍼푸릴 알코올(furfuryl alcohol), 폴리아크릴로니트릴, 폴리아미드, 퓨란 수지, 셀룰로오스, 스티렌, 폴리이미드, 에폭시 수지, 염화비닐 수지, 석탄계 피치, 석유계 피치, 메조페이스 피치, 타르, 저분자량 중질유, 또는 이들의 조합을 사용할 수 있다.The amorphous carbon precursors are sucrose, sucrose, methylene diphenyl diisocyanate, polyurethane, phenol resin, naphthalene resin, polyvinyl alcohol, polyvinyl chloride, furfuryl alcohol, and polyacrylo, respectively. Nitrile, polyamide, furan resin, cellulose, styrene, polyimide, epoxy resin, vinyl chloride resin, coal pitch, petroleum pitch, mesoface pitch, tar, low molecular weight heavy oil, or a combination thereof can be used.
상기 비정질 탄소의 코팅층 형성 시 코팅 방법은 특별히 제한되지 않으며, 예를 들면, 건식 코팅법, 액상 코팅법 등을 사용할 수 있다. 상기 건식 코팅의 예로는, 증착, CVD(chemical vapor deposition)법 등을 사용할 수 있으며, 액상 코팅의 예로는, 함침, 스프레이 등을 사용할 수 있다.The coating method is not particularly limited when forming the coating layer of amorphous carbon, and for example, a dry coating method, a liquid coating method, or the like may be used. Examples of the dry coating may be vapor deposition, chemical vapor deposition (CVD), or the like. Examples of the liquid coating may include impregnation and spraying.
상기 열처리는 비활성 분위기에서 500℃ 내지 700℃의 온도에서 수행될 수 있고, 예를 들면, 500℃ 내지 600℃에서 수행될 수 있다. 상기 온도 범위 내에서 열처리가 수행될 경우 활성 실리콘의 함량을 충분히 확보할 수 있으며, 탄화 공정시 불순물을 제거할 수 있고, 이에 따라 비가역 용량이 감소되어 충방전 특성이 개선될 수 있다.The heat treatment may be carried out at a temperature of 500 ℃ to 700 ℃ in an inert atmosphere, for example, may be carried out at 500 ℃ to 600 ℃. When the heat treatment is performed within the above temperature range, it is possible to sufficiently secure the content of the active silicon, to remove impurities during the carbonization process, thereby reducing the irreversible capacity may improve the charge and discharge characteristics.
이하, 상기 음극 활물질을 포함하는 리튬 이차 전지에 대해 도 2를 참고하여 설명한다.Hereinafter, a lithium secondary battery including the negative electrode active material will be described with reference to FIG. 2.
도 2는 일 구현예에 따른 리튬 이차 전지를 보여주는 개략도이다. 일 구현예에 따른 리튬 이차 전지는 원통형인 것을 예로 설명하지만, 본 발명이 이에 제한되는 것은 아니며, 각형 전지, 코인형, 파우치형 등 다양한 형태의 전지에 적용될 수 있다.2 is a schematic view showing a rechargeable lithium battery according to one embodiment. Although a lithium secondary battery according to one embodiment is described as an example of a cylindrical shape, the present invention is not limited thereto, and may be applied to various types of batteries, such as a square battery, a coin type, and a pouch type.
도 2를 참고하면, 일 구현예에 따른 리튬 이차 전지(100)는 양극(114), 양극(114)과 대향하는 음극(112), 양극(114)과 음극(112) 사이에 배치되어 있는 세퍼레이터(113), 그리고 양극(114), 음극(112) 및 세퍼레이터(113)를 함침하는 전해액(도시하지 않음)을 포함하는 전극 조립체와, 상기 전극 조립체를 담고 있는 전지 용기(120) 및 상기 전지 용기(120)를 밀봉하는 밀봉 부재(140)를 포함한다.Referring to FIG. 2, a lithium secondary battery 100 according to an embodiment includes a cathode 114, a cathode 112 facing the cathode 114, and a separator disposed between the anode 114 and the anode 112. An electrode assembly (113) and an electrolyte assembly (not shown) that impregnates the positive electrode 114, the negative electrode 112, and the separator 113, the battery container 120 containing the electrode assembly, and the battery container. And a sealing member 140 for sealing 120.
상기 음극(112)은 집전체 및 상기 집전체 위에 형성되는 음극 활물질층을 포함한다.The negative electrode 112 includes a current collector and a negative electrode active material layer formed on the current collector.
상기 집전체는 구리 박, 니켈 박, 스테인레스강 박, 티타늄 박, 니켈 발포체(foam), 구리 발포체, 전도성 금속이 코팅된 폴리머 기재, 또는 이들의 조합을 사용할 수 있으나, 이에 한정되는 것은 아니다.The current collector may be copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam (foam), copper foam, a polymer substrate coated with a conductive metal, or a combination thereof, but is not limited thereto.
상기 음극 활물질층은 음극 활물질을 포함하고, 선택적으로 바인더 및 도전재를 더 포함할 수 있다. 상기 음극 활물질은 전술한 바와 같다.The negative electrode active material layer may include a negative electrode active material, and may further include a binder and a conductive material. The negative electrode active material is as described above.
상기 바인더는 음극 활물질 입자들을 서로 잘 부착시키고, 또한 음극 활물질을 집전체에 잘 부착시키는 역할을 하며, 그 대표적인 예로 폴리비닐알코올, 카르복시메틸셀룰로오스, 히드록시프로필셀룰로오스, 폴리비닐클로라이드, 카르복실화된 폴리비닐클로라이드, 폴리비닐플루오라이드, 에틸렌 옥사이드 함유 폴리머, 폴리비닐피롤리돈, 폴리우레탄, 폴리테트라플루오로에틸렌, 폴리비닐리덴 플루오라이드, 폴리에틸렌, 폴리프로필렌, 스티렌-부타디엔 러버, 아크릴레이티드 스티렌-부타디엔 러버, 에폭시 수지, 나일론 등을 사용할 수 있으나, 이에 한정되는 것은 아니다.The binder adheres the negative electrode active material particles to each other well, and also serves to adhere the negative electrode active material to the current collector, and representative examples thereof include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, and carboxylated. Polyvinylchloride, polyvinylfluoride, ethylene oxide containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene- Butadiene rubber, epoxy resin, nylon and the like can be used, but are not limited thereto.
상기 도전재는 전극에 도전성을 부여하기 위해 사용되는 것으로서, 구성되는 전지에 있어서, 화학변화를 야기하지 않고 전자 전도성 재료이면 어떠한 것도 사용가능하며, 그 예로 천연 흑연, 인조 흑연, 그래핀, 카본 블랙, 아세틸렌 블랙, 케첸블랙, 탄소섬유 등의 탄소계 물질; 구리, 니켈, 알루미늄, 은 등의 금속 분말 또는 금속 섬유 등의 금속계 물질; 폴리페닐렌 유도체 등의 도전성 폴리머; 또는 이들의 혼합물을 포함하는 도전성 재료를 사용할 수 있다.The conductive material is used to impart conductivity to the electrode, and any battery can be used as long as it is an electronic conductive material without causing chemical change in the battery. For example, natural graphite, artificial graphite, graphene, carbon black, acetylene Carbon-based materials such as black, ketjen black, and carbon fiber; Metal materials such as metal powder or metal fibers such as copper, nickel, aluminum and silver; Conductive polymers such as polyphenylene derivatives; Or a conductive material containing a mixture thereof.
상기 양극(114)은 집전체 및 상기 집전체에 형성되는 양극 활물질층을 포함한다. 상기 양극 활물질층은 양극 활물질을 포함하고, 선택적으로 바인더 및 도전재를 더 포함할 수 있다.The positive electrode 114 includes a current collector and a positive electrode active material layer formed on the current collector. The cathode active material layer may include a cathode active material, and may further include a binder and a conductive material.
상기 집전체로는 Al(알루미늄)을 사용할 수 있으나, 이에 한정되는 것은 아니다. Al (aluminum) may be used as the current collector, but is not limited thereto.
상기 양극 활물질로는 리튬의 가역적인 인터칼레이션 및 디인터칼레이션이 가능한 화합물(리티에이티드 인터칼레이션 화합물)을 사용할 수 있다. 구체적으로는 코발트, 망간, 니켈 또는 이들의 조합의 금속과 리튬과의 복합 산화물 중 1종 이상의 것을 사용할 수 있으며, 그 구체적인 예로는 하기 화학식 중 어느 하나로 표현되는 화합물을 사용할 수 있다:As the cathode active material, a compound (lithiated intercalation compound) capable of reversible intercalation and deintercalation of lithium may be used. Specifically, one or more of complex oxides of metal and lithium of cobalt, manganese, nickel or a combination thereof may be used, and specific examples thereof may be a compound represented by one of the following formulas:
LiaA1 - bBbD2(상기 식에서, 0.90 ≤ a ≤ 1.8, 및 0 ≤ b ≤ 0.5이다); LiaE1 -bBbO2-cDc(상기 식에서, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05이다); LiE2-bBbO4-cDc(상기 식에서, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05이다); LiaNi1 -b- cCobBcDα(상기 식에서, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2이다); LiaNi1 -b- cCobBcO2 - αFα(상기 식에서, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2이다); LiaNi1 -b- cCobBcO2 - αF2(상기 식에서, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2이다); LiaNi1 -b- cMnbBcDα(상기 식에서, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2이다); LiaNi1 -b-cMnbBcO2-αFα(상기 식에서, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2이다); LiaNi1 -b- cMnbBcO2 - αF2(상기 식에서, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2이다); LiaNibEcGdO2(상기 식에서, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1이다.); LiaNibCocMndGeO2(상기 식에서, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤0.5, 0.001 ≤ e ≤ 0.1이다.); LiaNiGbO2(상기 식에서, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1이다.); LiaCoGbO2(상기 식에서, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1이다.); LiaMnGbO2(상기 식에서, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1이다.); LiaMn2GbO4(상기 식에서, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1이다.); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li(3-f)J2(PO4)3(0 ≤ f ≤ 2); Li(3-f)Fe2(PO4)3(0 ≤ f ≤ 2); 및 LiFePO4. Li a A 1 - b B b D 2 ( in the above formula, 0.90 ≤ a ≤ 1.8, and 0 ≤ b ≤ 0.5); Li a E 1 -b B b 0 2-c D c (wherein 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05); LiE 2-b B b 0 4-c D c (wherein 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05); Li a Ni 1 -b - c Co b B c D α (wherein 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, and 0 <α ≦ 2); Li a Ni 1 -b- c Co b B c O 2 - α F α ( wherein, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 <α <2 a); Li a Ni 1 -b- c Co b B c O 2 - α F 2 ( wherein, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 <α <2 a); Li a Ni 1 -b - c Mn b B c D α (wherein 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, and 0 <α ≦ 2); Li a Ni 1- bc Mn b B c O 2-α F α (wherein 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, and 0 <α <2); Li a Ni 1 -b- c Mn b B c O 2 - α F 2 ( wherein, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 <α <2 a); Li a Ni b E c G d O 2 (wherein 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.9, 0 ≦ c ≦ 0.5, and 0.001 ≦ d ≦ 0.1); Li a Ni b Co c Mn d GeO 2 (wherein 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.9, 0 ≦ c ≦ 0.5, 0 ≦ d ≦ 0.5, and 0.001 ≦ e ≦ 0.1); Li a NiG b O 2 (wherein 0.90 ≦ a ≦ 1.8 and 0.001 ≦ b ≦ 0.1); Li a CoG b O 2 (wherein 0.90 ≦ a ≦ 1.8 and 0.001 ≦ b ≦ 0.1); Li a MnG b O 2 (wherein 0.90 ≦ a ≦ 1.8 and 0.001 ≦ b ≦ 0.1); Li a Mn 2 G b O 4 (wherein 0.90 ≦ a ≦ 1.8 and 0.001 ≦ b ≦ 0.1); QO 2 ; QS 2 ; LiQS 2 ; V 2 O 5 ; LiV 2 O 5 ; LiIO 2 ; LiNiVO 4 ; Li (3-f) J 2 (PO 4 ) 3 (0 ≦ f ≦ 2); Li (3-f) Fe 2 (PO 4 ) 3 (0 ≦ f ≦ 2); And LiFePO 4 .
상기 화학식에 있어서, A는 Ni, Co, Mn 또는 이들의 조합이고; B는 Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, 희토류 원소 또는 이들의 조합이고; D는 O, F, S, P, 또는 이들의 조합이고; E는 Co, Mn 또는 이들의 조합이고; F는 F, S, P 또는 이들의 조합이고; G는 Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V 또는 이들의 조합이고; Q는 Ti, Mo, Mn 또는 이들의 조합이고; I는 Cr, V, Fe, Sc, Y 또는 이들의 조합이고; J는 V, Cr, Mn, Co, Ni, Cu 또는 이들의 조합일 수 있다.In the above formula, A is Ni, Co, Mn or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or combinations thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn or a combination thereof; F is F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; Q is Ti, Mo, Mn or a combination thereof; I is Cr, V, Fe, Sc, Y or a combination thereof; J may be V, Cr, Mn, Co, Ni, Cu or a combination thereof.
상기 바인더는 양극 활물질 입자들을 서로 잘 부착시키고, 또한 양극 활물질을 양극 집전체에 잘 부착시키는 역할을 하며, 구체적인 예로는 폴리비닐알콜, 카르복시메틸셀룰로오스, 히드록시프로필셀룰로오스, 디아세틸셀룰로오스, 폴리비닐클로라이드, 카르복실화된 폴리비닐클로라이드, 폴리비닐플루오라이드, 에틸렌 옥사이드 함유 폴리머, 폴리비닐피롤리돈, 폴리우레탄, 폴리테트라플루오로에틸렌, 폴리비닐리덴 플루오라이드, 폴리에틸렌, 폴리프로필렌, 스티렌-부타디엔 러버, 아크릴레이티드 스티렌-부타디엔 러버, 에폭시 수지, 나일론 등을 들 수 있으나, 이에 한정되는 것은 아니다.The binder adheres positively to the positive electrode active material particles, and also serves to adhere the positive electrode active material to the positive electrode current collector, and specific examples thereof include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, and polyvinyl chloride. , Carboxylated polyvinylchloride, polyvinylfluoride, ethylene oxide containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, Acrylated styrene-butadiene rubber, epoxy resin, nylon, and the like, but are not limited thereto.
상기 도전재는 전극에 도전성을 부여하기 위해 사용되는 것으로서, 구성되는 전지에 있어서, 화학변화를 야기하지 않고 전자 전도성 재료이면 어떠한 것도 사용가능하며, 그 예로 천연 흑연, 인조 흑연, 그래핀, 카본 블랙, 아세틸렌 블랙, 케첸블랙, 탄소섬유, 구리, 니켈, 알루미늄, 은 등의 금속 분말, 금속 섬유 등을 사용할 수 있고, 또한 폴리페닐렌 유도체 등의 도전성 재료를 1종 또는 1종 이상을 혼합하여 사용할 수 있다.The conductive material is used to impart conductivity to the electrode, and any battery can be used as long as it is an electronic conductive material without causing chemical change in the battery. For example, natural graphite, artificial graphite, graphene, carbon black, acetylene Metal powders, such as black, Ketjen black, carbon fiber, copper, nickel, aluminum, silver, metal fiber, etc. can be used, and 1 type (s) or 1 or more types can be mixed and conductive materials, such as a polyphenylene derivative, can be used. .
상기 양극 및 음극은 각각 활물질, 도전재 및 바인더를 용매 중에 혼합하여 활물질 조성물을 제조하고, 이 조성물을 집전체에 도포하여 제조한다. 상기 용매로는 N-메틸피롤리돈 등을 사용할 수 있고, 상기 바인더로 수계 바인더를 사용한 경우에는 물을 사용할 수도 있으나, 이에 한정되는 것은 아니다. 이와 같은 전극 제조 방법은 당해 분야에 널리 알려진 내용이므로 본 명세서에서 상세한 설명은 생략하기로 한다.The positive electrode and the negative electrode are prepared by mixing an active material, a conductive material, and a binder in a solvent to prepare an active material composition, and applying the composition to a current collector. N-methylpyrrolidone may be used as the solvent, and water may be used when an aqueous binder is used as the binder, but is not limited thereto. Since such an electrode manufacturing method is well known in the art, detailed description thereof will be omitted.
상기 전해액은 유기용매와 리튬염을 포함한다.The electrolyte solution contains an organic solvent and a lithium salt.
상기 유기용매는 전지의 전기화학적 반응에 관여하는 이온들이 이동할 수 있는 매질 역할을 한다. 상기 유기용매는 카보네이트계, 에스테르계, 에테르계, 케톤계, 알코올계 등에서 선택될 수 있다.The organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move. The organic solvent may be selected from carbonate, ester, ether, ketone, alcohol, and the like.
상기 카보네이트계 용매로는 예컨대 디메틸 카보네이트(dimethyl carbonate, DMC), 디에틸 카보네이트(diethyl carbonate, DEC), 디프로필 카보네이트(dipropyl carbonate, DPC), 메틸프로필 카보네이트(methylpropyl carbonate, MPC), 에틸프로필 카보네이트(ethylpropyl carbonate, EPC), 에틸메틸 카보네이트(ethylmethyl carbonate, EMC), 에틸렌 카보네이트(ethylene carbonate, EC), 프로필렌 카보네이트(propylene carbonate, PC), 부틸렌 카보네이트(butylene carbonate, BC) 등이 사용될 수 있다. Examples of the carbonate solvent include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), and ethylpropyl carbonate ( Ethylpropyl carbonate (EPC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) and the like may be used.
특히, 사슬형 카보네이트 화합물 및 환형 카보네이트 화합물을 혼합하여 사용하는 경우, 유전율을 높이는 동시에 점성이 작은 용매로 제조될 수 있다. 이 경우 환형 카보네이트 화합물 및 사슬형 카보네이트 화합물은 약 1:1 내지 1:9의 부피비로 혼합하여 사용할 수 있다. In particular, when a mixture of the chain carbonate compound and the cyclic carbonate compound is used, it can be prepared with a solvent having a high viscosity and a low viscosity. In this case, the cyclic carbonate compound and the chain carbonate compound may be mixed and used in a volume ratio of about 1: 1 to 1: 9.
또한 상기 에스테르계 용매로는 예컨대 메틸아세테이트, 에틸아세테이트, n-프로필아세테이트, 메틸프로피오네이트, 에틸프로피오네이트, γ-부티로락톤, 데카놀라이드(decanolide), 발레로락톤, 메발로노락톤(mevalonolactone), 카프로락톤(caprolactone) 등이 사용될 수 있다. 상기 에테르 용매로는 예컨대 디부틸에테르, 테트라글라임, 디글라임, 디메톡시에탄, 2-메틸테트라히드로퓨란, 테트라히드로퓨란 등이 사용될 수 있으며, 상기 케톤계 용매로는 시클로헥사논 등이 사용될 수 있다. 또한 상기 알코올계 용매로는 에틸알코올, 이소프로필 알코올 등이 사용될 수 있다.In addition, the ester solvent is, for example, methyl acetate, ethyl acetate, n-propyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, decanolide, valerolactone, mevalonolactone (mevalonolactone), caprolactone and the like can be used. As the ether solvent, for example, dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, etc. may be used. As the ketone solvent, cyclohexanone may be used. have. In addition, ethyl alcohol, isopropyl alcohol, etc. may be used as the alcohol solvent.
상기 유기용매는 단독 또는 하나 이상 혼합하여 사용할 수 있으며, 하나 이상 혼합하여 사용하는 경우의 혼합 비율은 목적하는 전지 성능에 따라 적절하게 조절할 수 있다.The organic solvent may be used singly or in mixture of one or more, and the mixing ratio in the case of mixing one or more may be appropriately adjusted according to the desired battery performance.
상기 전해액은 에틸렌카보네이트, 피로카보네이트 등의 과충전 방지제와 같은 첨가제를 더 포함할 수도 있다.The electrolyte solution may further include an additive such as an overcharge inhibitor such as ethylene carbonate and pyrocarbonate.
상기 리튬염은 유기용매에 용해되어, 전지 내에서 리튬 이온의 공급원으로 작용하여 기본적인 리튬 이차 전지의 작동을 가능하게 하고, 양극과 음극 사이의 리튬 이온의 이동을 촉진하는 역할을 하는 물질이다. The lithium salt is a substance that dissolves in an organic solvent and acts as a source of lithium ions in the battery to enable operation of a basic lithium secondary battery and to promote the movement of lithium ions between the positive electrode and the negative electrode.
상기 리튬염의 구체적인 예로는 LiPF6, LiBF4, LiSbF6, LiAsF6, LiN(SO3C2F5)2, LiN(CF3SO2)2, LiC4F9SO3, LiClO4, LiAlO2, LiAlCl4, LiN(CxF2x + 1SO2)(CyF2y + 1SO2)(여기서, x 및 y는 자연수임), LiCl, LiI, LiB(C2O4)2(리튬 비스옥살레이토 보레이트(lithium bis(oxalato) borate; LiBOB), 또는 이들의 조합을 들 수 있다.Specific examples of the lithium salt include LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiN (SO 3 C 2 F 5 ) 2 , LiN (CF 3 SO 2 ) 2 , LiC 4 F 9 SO 3 , LiClO 4 , LiAlO 2 , LiAlCl 4 , LiN (C x F 2x + 1 SO 2 ) (C y F 2y + 1 SO 2 ), where x and y are natural numbers, LiCl, LiI, LiB (C 2 O 4 ) 2 (lithium And bisoxalato borate (LiBOB), or a combination thereof.
상기 리튬염의 농도는 약 0.1M 내지 약 2.0M 범위 내에서 사용하는 것이 좋다. 리튬염의 농도가 상기 범위에 포함되면, 전해액이 적절한 전도도 및 점도를 가지므로 우수한 전해액 성능을 나타낼 수 있고, 리튬 이온이 효과적으로 이동할 수 있다.The concentration of the lithium salt is preferably used within the range of about 0.1M to about 2.0M. When the concentration of the lithium salt is included in the above range, since the electrolyte has an appropriate conductivity and viscosity, it can exhibit excellent electrolyte performance, and lithium ions can move effectively.
상기 세퍼레이터(113)는 음극과 양극을 분리하고 리튬 이온의 이동 통로를 제공하는 것으로 리튬 전지에서 통상적으로 사용되는 것이라면 모두 사용가능하다.　 즉, 전해질의 이온 이동에 대하여 저저항이면서 전해액 함습 능력이 우수한 것이 사용될 수 있다.　 예를 들어, 유리 섬유, 폴리에스테르, 폴리에틸렌, 폴리프로필렌, 폴리테트라플루오로에틸렌(PTFE) 또는 이들의 조합물 중에서 선택된 것으로서, 부직포 또는 직포 형태이어도 무방하다.　 예를 들어, 리튬이온전지에는 폴리에틸렌, 폴리프로필렌 등과 같은 폴리올레핀계 고분자 세퍼레이터가 주로 사용되고, 내열성 또는 기계적 강도 확보를 위해 세라믹 성분 또는 고분자 물질이 포함된 코팅된 세퍼레이터가 사용될 수도 있으며, 선택적으로 단층 또는 다층 구조로 사용될 수 있다.The separator 113 separates the negative electrode from the positive electrode and provides a passage for moving lithium ions, and any separator can be used as long as it is commonly used in a lithium battery. In other words, those having low resistance to ion migration of the electrolyte and excellent electrolyte-wetting ability can be used. For example, it is selected from glass fiber, polyester, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or a combination thereof, and may be in a nonwoven or woven form. For example, a polyolefin-based polymer separator such as polyethylene or polypropylene is mainly used for a lithium ion battery, and a coated separator including a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength. Can be used as a structure.
이하에서는 본 발명의 구체적인 실시예들을 제시한다. 　다만, 하기에 기재된 실시예들은 본 발명을 구체적으로 예시하거나 설명하기 위한 것에 불과하며, 이로서 본 발명이 제한되어서는 아니된다. 또한, 여기에 기재되지 않은 내용은 이 기술 분야에서 숙련된 자이면 충분히 기술적으로 유추할 수 있는 것이므로 그 설명을 생략한다.The following presents specific embodiments of the present invention. However, the embodiments described below are merely for illustrating or explaining the present invention in detail, and thus the present invention is not limited thereto. In addition, the description is not described herein, so those skilled in the art that can be sufficiently technically inferred the description thereof will be omitted.
(음극 활물질 제조)(Cathode active material production)
실시예Example 1 One
Si 80 원자% 및 Fe 20 원자%를 혼합한 후, 이를 진공유도 용해로(예인테크, Yein Tech., Korea)에 투입하고, 대기에 의한 산화를 최대한 억제하기 위하여 진공분위기 하에서 용해시켜 모합금을 제조하였다. 상기 모합금을 큰 덩어리 상태로 분쇄한 후, 멜트 스피너(예인테크, Yein Tech., Korea)의 사출관 속에 넣고, 아르곤 가스 분위기 속에서 고주파 유도 가열하여 모합금을 용융시키고, 용융된 모합금을 노즐을 통해 회전하는 Cu 휠에 분사하여 리본 형태로 합금을 사출하고 급속 응고시켰다. 생성된 합금 리본을 고에너지 볼밀을 이용하여 장시간 밀링을 진행하여 미립화 및 비정질화하여 평균입경이 2.3㎛의 FeSi2 분말을 얻었다. After mixing 80 atomic% Si and 20 atomic% Fe, it is introduced into a vacuum induction melting furnace (Yein Tech., Korea), and dissolved in a vacuum atmosphere to maximize oxidation by the atmosphere to prepare a master alloy. It was. After crushing the master alloy in a large lump state, it is placed in an injection tube of a melt spinner (Yein Tech., Korea), and the mother alloy is melted by high frequency induction heating in an argon gas atmosphere, and the molten master alloy is melted. The alloy was ejected in the form of a ribbon by spraying on a rotating Cu wheel through the nozzle and solidified rapidly. The resulting alloy ribbon was milled using a high energy ball mill for a long time to be atomized and amorphous to obtain FeSi 2 powder having an average particle diameter of 2.3 μm.
이어서, FeSi2 분말 100 중량부와 평균입경이 3 nm인 카본 블랙Subsequently, carbon black having 100 parts by weight of FeS i2 powder and an average particle diameter of 3 nm
(superP)(TIMCAL社) 3 중량부를 혼합한 후, 분말코팅기(메카노퓨젼)를 이용하여 카본 블랙을 표면에 부착시킨 FeSi2 분말을 제조하였다. 이어서, 카본 블랙이 표면에 부착된 FeSi2 분말 89.0 중량%, 콜타르 피치 10.0 중량%, 그리고 6㎛ 길이를 가진 탄소 나노 튜브 1.0 중량%를 건식법인 볼밀법으로 혼합한 다음, 질소 분위기 하에 500℃에서 열처리하여, 상기 FeSi2 분말의 표면에 1㎛ 두께의 탄소 코팅층이 형성된 음극 활물질을 제조하였다. After mixing 3 parts by weight of (superP) (TIMCAL), FeSi 2 powder having carbon black attached to the surface was prepared using a powder coating machine (mechanofusion). Subsequently, 89.0% by weight of FeS i2 powder, 10.0% by weight of coal tar, and 1.0% by weight of carbon nanotubes having a 6 μm length, were carbon-mixed on the surface by a ball mill method in a dry method, and then at 500 ° C. under a nitrogen atmosphere. Heat treatment was performed to prepare a negative electrode active material having a carbon coating layer having a thickness of 1 μm on the surface of the FeSi 2 powder.
실시예Example 2 2
카본 블랙이 표면에 부착된 FeSi2 분말 89.5 중량%, 콜타르 피치 10.0중량%, 그리고 탄소 나노 튜브 0.5중량%를 혼합하여 열처리한 것을 제외하고는, 실시예 1과 동일한 방법으로 음극 활물질을 제조하였다. A negative electrode active material was prepared in the same manner as in Example 1, except that 89.5% by weight of FeSi 2 powder, 10.0% by weight of coal tar, and 0.5% by weight of carbon nanotubes were mixed and heat treated with carbon black.
실시예Example 3 3
카본 블랙이 표면에 부착된 FeSi2 분말 88.0 중량%, 콜타르 피치 10.0 중량%, 그리고 탄소 나노 튜브 2.0 중량%를 혼합하여 열처리한 것을 제외하고는, 실시예 1과 동일한 방법으로 음극 활물질을 제조하였다. A negative electrode active material was prepared in the same manner as in Example 1, except that 88.0% by weight of FeSi 2 powder, 10.0% by weight of coal tar, and 2.0% by weight of carbon nanotubes were mixed with carbon black.
비교예Comparative example 1 One
실시예 1에서 제조된 카본 블랙을 표면에 부착시킨 FeSi2 분말을 음극 활물질로 사용하였다.FeSi 2 powder having carbon black prepared in Example 1 attached to the surface was used as a negative electrode active material.
비교예Comparative example 2 2
실시예 1에서 제조된 카본 블랙이 표면에 부착된 FeSi2 분말 90.0 중량% 및 콜타르 피치 10.0중량%를 건식법인 볼밀법으로 혼합한 다음, 질소 분위기 하에 500℃에서 열처리하여, 상기 FeSi2 분말의 표면에 1㎛ 두께의 탄소 코팅층이 형성된 음극 활물질을 제조하였다. 90.0% by weight of the FeSi2 powder and coal tar pitch 10.0% by weight of the carbon black prepared in Example 1 were mixed by a ball mill method of a dry method, and then heat-treated at 500 ° C. under a nitrogen atmosphere to the surface of the FeSi 2 powder. An anode active material having a carbon coating layer having a thickness of 1 μm was prepared.
(리튬 이차 전지 제작)(Lithium secondary battery production)
실시예 1 내지 3 및 비교예 1 내지 3에서 제조된 음극 활물질 97 중량%, 카르복시메틸셀룰로오스 1.5 중량% 및 스티렌-부타디엔 러버 1.5 중량%를 증류수에 혼합하여 슬러리를 제조하였다. 상기 슬러리를 Cu 박에 도포, 건조 및 압연하여 음극을 제조하였다. Slurry was prepared by mixing 97% by weight of the negative electrode active material prepared in Examples 1 to 3 and Comparative Examples 1 to 3, 1.5% by weight of carboxymethylcellulose and 1.5% by weight of styrene-butadiene rubber in distilled water. The slurry was applied to Cu foil, dried and rolled to prepare a negative electrode.
LiCoO2 97.4 중량%, 폴리비닐리덴플루오라이드(PVdF) 1.4 중량% 및 카본 블랙 1.3 중량%를 N-메틸피롤리돈에 혼합하여 슬러리를 제조하고, 이를 Al 박에 도포, 건조 및 압연하여 양극을 제조하였다. 97.4% by weight of LiCoO 2 , 1.4% by weight of polyvinylidene fluoride (PVdF) and 1.3% by weight of carbon black were mixed with N-methylpyrrolidone to prepare a slurry, which was applied to Al foil, dried and rolled to form a positive electrode. Prepared.
상기 음극 및 양극, 폴리에틸렌 재질의 세퍼레이터, 그리고 전해액을 사용하여 리튬 이차 전지를 제작하였다. 이때 전해액으로는 에틸렌 카보네이트(EC), 디에틸 카보네이트(DEC) 및 플루오로에틸렌 카보네이트(FEC)를 3:3:4의 부피비로 혼합한 유기용매에 1.1M의 LiPF6을 용해한 것을 사용하였다. A lithium secondary battery was manufactured using the negative electrode and the positive electrode, a polyethylene separator, and an electrolyte solution. At this time, 1.1 M of LiPF 6 was dissolved in an organic solvent in which ethylene carbonate (EC), diethyl carbonate (DEC) and fluoroethylene carbonate (FEC) were mixed in a volume ratio of 3: 3: 4.
평가 1: 실리콘계 합금의 상 분석Evaluation 1: Phase Analysis of Silicon-Based Alloys
실시예 1에서 제조된 FeSi2 분말에 대하여 X-선 회절(XRD)을 이용한 상 분석 결과를 도 3에 나타내었다. XRD 분석 조건은 CuKα 특성 X-선 파장 1.541Å 이었다.Phase analysis of the FeSi 2 powder prepared in Example 1 using X-ray diffraction (XRD) is shown in FIG. 3. XRD analysis conditions were CuKα characteristic X-ray wavelength of 1.541 kHz.
도 3은 실시예 1에서 제조된 실리콘계 합금의 X-선 회절(XRD) 분석 그래프이다. 3 is an X-ray diffraction (XRD) analysis graph of the silicon-based alloy prepared in Example 1. FIG.
도 3을 참고하면, 실시예 1에서 제조된 실리콘계 합금은 Si2Fe　상만이 비활성 상으로 나타나며, 비활성 매트릭스를 이루지 못한 40 원자%의 Si은 활성 상으로 나타남을 알 수 있다. 즉, 실시예 1의 실리콘계 합금은 비활성 상인 Si2Fe와 활성 상인 Si은 각각 60 원자% 및 40 원자%로 이루어짐을 알 수 있다. 이때 상기 활성 상인 Si의 평균입경은 100nm 이하 임을 알 수 있다.Referring to FIG. 3, it can be seen that in the silicon-based alloy prepared in Example 1, only Si 2 Fe phase appeared as an inactive phase, and 40 atomic% Si which did not form an inactive matrix appeared as an active phase. That is, it can be seen that the silicon-based alloy of Example 1 is composed of 60 atomic% and 40 atomic% of Si 2 Fe which is an inactive phase and Si which is an active phase, respectively. In this case, it can be seen that the average particle diameter of the active phase Si is 100 nm or less.
평가 2: 음극 활물질의 FE-Evaluation 2: FE- of the negative electrode active material SEMSEM 분석 analysis
도 4 내지 6은 각각 실시예 1, 비교예 1 및 비교예 2에 따른 음극 활물질의 전계방사 주사전자현미경(FE-SEM) 사진이다. 도 4 내지 6을 참고하면, 실시예 1의 음극 활물질은 실리콘계 합금 입자 표면에 비정질 탄소의 코팅층이 형성되고 도전재가 상기 코팅층의 내부에 위치하는 구조로 형성됨을 알 수 있다. 반면, 비교예 1의 음극 활물질은 비정질 탄소 코팅층이 형성되지 않았고, 비교예 2의 음극 활물질은 도전재가 존재하지 않음을 알 수 있다. 4 to 6 are field emission scanning electron microscope (FE-SEM) photographs of the negative electrode active materials according to Example 1, Comparative Example 1, and Comparative Example 2, respectively. 4 to 6, it can be seen that the negative electrode active material of Example 1 has a structure in which a coating layer of amorphous carbon is formed on a surface of a silicon-based alloy particle and a conductive material is positioned inside the coating layer. On the other hand, the negative electrode active material of Comparative Example 1 did not have an amorphous carbon coating layer, it can be seen that the negative electrode active material of Comparative Example 2 does not have a conductive material.
평가 3: 리튬 이차 전지의 수명 특성Evaluation 3: Life Characteristics of Lithium Secondary Batteries
실시예 1 및 비교예 2에 따라 제작된 리튬 이차 전지에 대하여 하기 조건으로 충방전을 3 회씩 진행하여 용량 유지율(capacity retention ratio, CRR)을 분석하였고, 그 결과를 도 7에 나타내었다. The charge and discharge of the lithium secondary batteries prepared according to Example 1 and Comparative Example 2 was performed three times under the following conditions to analyze capacity retention ratio (CRR), and the results are shown in FIG. 7.
충전 0.5C, 4.2V, 컷-오프 0.05CCharge 0.5C, 4.2V, Cut-off 0.05C
방전 1.0C, 컷-오프 2.5V Discharge 1.0C, Cut-Off 2.5V
상기 용량 유지율은 하기 수학식 1에 의해 산출된다.The capacity retention rate is calculated by the following equation.
[수학식 1][Equation 1]
용량 유지율(%) = (각 사이클에서의 방전용량 / 첫 번째 사이클에서의 방전용량) X 100Capacity retention rate (%) = (discharge capacity in each cycle / discharge capacity in the first cycle) X 100
도 7을 참고하면, 탄소 나노 입자가 표면에 부착된 실리콘계 합금을 비정질 탄소의 코팅층이 둘러싸고 상기 코팅층 내부에 도전재의 적어도 일부가 위치하는 구조의 음극 활물질을 사용한 실시예 1의 경우, 비교예 2 대비 수명 특성이 우수함을 알 수 있다. 이로부터, 상기 구조를 가진 음극 활물질은 전기 전도성이 향상됨으로써 리튬 이차 전지의 수명 특성이 개선됨을 알 수 있다. 이상에서 본 발명의 바람직한 실시예들에 대하여 상세하게 설명하였지만 본 발명의 권리 범위는 이에 한정되는 것은 아니고 다음의 청구 범위에서 정의하고 있는 본 발명의 기본 개념을 이용한 당업자의 여러 변형 및 개량 형태 또한 본 발명의 권리 범위에 속하는 것이다.Referring to FIG. 7, in the case of Example 1 using a negative active material having a structure in which a coating layer of amorphous carbon surrounds a silicon-based alloy on which carbon nanoparticles are attached to a surface and at least a portion of the conductive material is disposed in the coating layer, compared to Comparative Example 2 It can be seen that the life characteristics are excellent. From this, it can be seen that the negative electrode active material having the above structure improves the life characteristics of the lithium secondary battery by improving electrical conductivity. Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of the invention.

Claims (16)

  1. 실리콘계 합금을 포함하는 코어 입자;Core particles comprising a silicon-based alloy;
    상기 코어 입자의 표면에 부착된 탄소 나노 입자; Carbon nanoparticles attached to the surface of the core particles;
    상기 탄소 나노 입자가 표면에 부착된 코어 입자를 둘러싸고 비정질 탄소를 포함하는 코팅층; 및A coating layer surrounding the core particles to which the carbon nanoparticles are attached and including amorphous carbon; And
    상기 코팅층의 표면에 위치하는 도전재를 포함하고,It includes a conductive material located on the surface of the coating layer,
    상기 도전재 중 적어도 일부는 상기 코팅층의 내부에 위치하고,At least some of the conductive material is located inside the coating layer,
    상기 탄소 나노 입자는 상기 비정질 탄소와 동일하거나 상이하고, The carbon nanoparticles are the same as or different from the amorphous carbon,
    상기 도전재는 상기 탄소 나노 입자 및 상기 비정질 탄소와 상이한 리튬 이차 전지용 음극 활물질.The conductive material is a negative electrode active material for a lithium secondary battery different from the carbon nanoparticles and the amorphous carbon.
  2. 제1항에서,In claim 1,
    상기 도전재는 탄소 나노 튜브, 탄소 나노 섬유, 천연흑연, 인조흑연, 그래핀, 카본 블랙, 또는 이들의 조합을 포함하는 리튬 이차 전지용 음극 활물질.The conductive material is a negative electrode active material for a lithium secondary battery containing carbon nanotubes, carbon nanofibers, natural graphite, artificial graphite, graphene, carbon black, or a combination thereof.
  3. 제1항에서,In claim 1,
    상기 도전재 중 적어도 일부는 상기 코팅층의 내부에 위치하여 상기 코어 입자와 접촉하는 리튬 이차 전지용 음극 활물질.At least some of the conductive material is located inside the coating layer to contact the core particles in a lithium secondary battery negative electrode active material.
  4. 제1항에서,In claim 1,
    상기 도전재 중 적어도 일부는 상기 코어 입자의 내부에 위치하는 리튬 이차 전지용 음극 활물질.At least a portion of the conductive material is a negative electrode active material for a lithium secondary battery located inside the core particles.
  5. 제1항에서,In claim 1,
    상기 도전재의 길이는 6㎛ 내지 12㎛ 리튬 이차 전지용 음극 활물질.The conductive material has a length of 6 μm to 12 μm for a negative active material for a lithium secondary battery.
  6. 제1항에서,In claim 1,
    상기 도전재의 함량은 상기 음극 활물질의 총량에 대하여 0.5 중량% 내지 2.0 중량%인 리튬 이차 전지용 음극 활물질.The amount of the conductive material is 0.5% by weight to 2.0% by weight of the negative electrode active material based on the total amount of the negative electrode active material.
  7. 제1항에서,In claim 1,
    상기 탄소 나노 입자의 평균입경은 상기 코어 입자의 평균입경 대비 1/10 이하인 리튬 이차 전지용 음극 활물질.The average particle diameter of the carbon nanoparticles is 1/10 or less than the average particle diameter of the core particles lithium secondary battery negative electrode active material.
  8. 제1항에서,In claim 1,
    상기 탄소 나노 입자는 1 nm 내지 100 nm의 평균입경을 가지는 비정질 탄소 입자를 포함하는 리튬 이차 전지용 음극 활물질.The carbon nanoparticles are anode active materials for lithium secondary batteries comprising amorphous carbon particles having an average particle diameter of 1 nm to 100 nm.
  9. 제1항에서,In claim 1,
    상기 실리콘계 합금은 하기 화학식 1로 표시되는 리튬 이차 전지용 음극 활물질.The silicon-based alloy is a negative electrode active material for a lithium secondary battery represented by the formula (1).
    [화학식 1][Formula 1]
    SiaMb Si a M b
    (상기 화학식 1에서, M은 실리콘을 제외한 2족 내지 14족 금속원소 중 적어도 하나를 포함하고, 0.5≤a≤0.9, 0.1≤b≤0.5, 및 a+b=1이다.)(In Formula 1, M includes at least one of Group 2 to Group 14 metal elements except silicon, and 0.5 ≦ a ≦ 0.9, 0.1 ≦ b ≦ 0.5, and a + b = 1.)
  10. 제9항에서,In claim 9,
    상기 M은 철(Fe), 구리(Cu), 마그네슘(Mg), 크롬(Cr), 니켈(Ni), 아연(Zn), 망간(Mn), 코발트(Co), 티타늄(Ti), 게르마늄(Ge), 칼슘(Ca), 알루미늄(Al) 또는 이들의 조합을 포함하는 리튬 이차 전지용 음극 활물질.The M is iron (Fe), copper (Cu), magnesium (Mg), chromium (Cr), nickel (Ni), zinc (Zn), manganese (Mn), cobalt (Co), titanium (Ti), germanium ( Ge), calcium (Ca), aluminum (Al), or a combination thereof, a negative electrode active material for a lithium secondary battery.
  11. 제1항에서,In claim 1,
    상기 코어 입자는The core particle is
    실리콘 및 실리콘을 제외한 2족 내지 14족 금속원소 중 적어도 하나를 포함하는 비활성 매트릭스; 및 An inert matrix comprising at least one of silicon and Group 2 to 14 metal elements excluding silicon; And
    상기 비활성 매트릭스 내에 분산된 활성 실리콘 나노 입자Active silicon nanoparticles dispersed in the inert matrix
    를 포함하는 리튬 이차 전지용 음극 활물질.A negative electrode active material for a lithium secondary battery comprising a.
  12. 제11항에서,In claim 11,
    상기 활성 실리콘 나노 입자의 함량은 상기 실리콘계 합금의 총 원자량에 대하여 30 원자% 내지 50 원자%인 리튬 이차 전지용 음극 활물질.The amount of the active silicon nanoparticles is 30 atomic% to 50 atomic% with respect to the total atomic weight of the silicon-based alloy negative electrode active material.
  13. 제11항에서,In claim 11,
    상기 활성 실리콘 나노 입자의 평균입경은 1 nm 내지 100 nm 인 리튬 이차 전지용 음극 활물질.An average active particle diameter of the active silicon nanoparticles is 1 nm to 100 nm negative electrode active material for a lithium secondary battery.
  14. 제1항에서,In claim 1,
    상기 코팅층의 두께는 10 nm 내지 10 ㎛ 인 리튬 이차 전지용 음극 활물질.The coating layer has a thickness of 10 nm to 10 ㎛ negative electrode active material for a secondary battery.
  15. 실리콘계 합금을 포함하는 코어 입자, 그리고 탄소 나노 입자를 혼합하여 제1 입자를 얻는 단계;Mixing the core particles including the silicon-based alloy, and the carbon nanoparticles to obtain first particles;
    상기 제1 입자, 비정질 탄소 전구체, 그리고 도전재를 혼합하여 제2 입자를 얻는 단계; 및Mixing the first particles, the amorphous carbon precursor, and the conductive material to obtain second particles; And
    상기 제2 입자를 열처리하는 단계를 포함하고,Heat-treating the second particles;
    상기 탄소 나노 입자는 상기 비정질 탄소 전구체와 동일하거나 상이하고, The carbon nanoparticles are the same as or different from the amorphous carbon precursor,
    상기 도전재는 상기 탄소 나노 입자 및 상기 비정질 탄소 전구체와 상이한 리튬 이차 전지용 음극 활물질의 제조 방법.The conductive material is a method for producing a negative electrode active material for a lithium secondary battery different from the carbon nanoparticles and the amorphous carbon precursor.
  16. 제1항 내지 제14항 중 어느 한 항의 음극 활물질을 포함하는 음극A negative electrode comprising the negative electrode active material of any one of claims 1 to 14
    을 포함하는 리튬 이차 전지.Lithium secondary battery comprising a.
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KR20150133167A (en) * 2012-11-30 2015-11-27 주식회사 엘지화학 Anode active material for lithium secondary battery and Lithium secondary battery comprising the same

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US11824189B2 (en) 2018-01-09 2023-11-21 South Dakota Board Of Regents Layered high capacity electrodes
CN108682787A (en) * 2018-06-12 2018-10-19 四会市恒星智能科技有限公司 A kind of electrodes of lithium-ion batteries and preparation method thereof
CN108682787B (en) * 2018-06-12 2020-10-09 安徽正熹标王新能源有限公司 Lithium ion battery pole piece and preparation method thereof
CN112714971A (en) * 2019-01-21 2021-04-27 株式会社Lg化学 Negative electrode active material for lithium secondary battery, and negative electrode and lithium secondary battery comprising same
US11962003B2 (en) 2019-01-21 2024-04-16 Lg Energy Solution, Ltd. Negative electrode active material for lithium secondary battery, and negative electrode and lithium secondary battery including the same
CN110336001A (en) * 2019-06-26 2019-10-15 纳诺思能源有限公司 Carbon-silicon composite material and preparation method thereof with nucleocapsid bilayer substructure
CN114899368A (en) * 2022-03-28 2022-08-12 佛山市德方纳米科技有限公司 Composite cathode material and preparation method and application thereof

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