WO2015111954A1 - 리튬이차전지용 음극 활물질 및그 제조방법, 이를 이용한 리튬 이차전지 - Google Patents

리튬이차전지용 음극 활물질 및그 제조방법, 이를 이용한 리튬 이차전지 Download PDF

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WO2015111954A1
WO2015111954A1 PCT/KR2015/000728 KR2015000728W WO2015111954A1 WO 2015111954 A1 WO2015111954 A1 WO 2015111954A1 KR 2015000728 W KR2015000728 W KR 2015000728W WO 2015111954 A1 WO2015111954 A1 WO 2015111954A1
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active material
lithium secondary
secondary battery
diisocyanate
polyol
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PCT/KR2015/000728
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English (en)
French (fr)
Inventor
이종혁
윤태균
홍수형
이정무
신상용
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애경유화 주식회사
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Priority to JP2016546447A priority Critical patent/JP6301484B2/ja
Publication of WO2015111954A1 publication Critical patent/WO2015111954A1/ko

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • 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 provides a cathode active material for a lithium secondary battery and a method for manufacturing the same, using the same
  • the lithium secondary battery is more specifically related to a cathode active material for a lithium secondary battery and a method of manufacturing the lithium secondary battery, which has improved battery characteristics such as excellent life characteristics, layer discharge output, and high temperature storage characteristics.
  • Lithium rechargeable batteries have recently become a popular power source for electric vehicles driven by electric motors, while demand for eco-friendly green cars is increasing.
  • smartphones, tablet PCs and ultrabooks are also becoming popular. Thanks to the advancement of technology of electronic devices, the utilization is getting wider.
  • Patent Document 1 Korean Unexamined Patent Publication No. 10-2014-0140323 discloses spherical graphite
  • Lithium which is formed by coating with a low crystalline granular material selected from petroleum pitch, coal pitch, low molecular weight heavy oil, etc. on the surface of the core, is disclosed for the negative electrode active material for secondary batteries.
  • a low crystalline granular material selected from petroleum pitch, coal pitch, low molecular weight heavy oil, etc.
  • the effect of suppressing some non-reversible reaction Although the low crystalline granular material coated on the spherical graphite surface flows during the firing process, it is difficult to obtain a uniform coating.
  • Patent Document 1 Republic of Korea Patent Application Publication No. 10-201 4 -01 4 03 2 3 ( 2 014.1 2 .09)
  • the present invention is intended to solve a conventional problem.
  • An object of the present invention is to provide a cathode active material for lithium secondary batteries with excellent characteristics and lifespan characteristics and a method of manufacturing the same.
  • the purpose is to provide.
  • the present invention relates to a cathode active material for a lithium secondary battery including a carbon composite obtained by heat-treating a carbon-based granular material coated with a thermosetting resin composition containing an isocyanate compound under an inert gas atmosphere.
  • thermosetting resin composition is cured on the surface of the granular material to form a polyurethane resin
  • polyurethane resin may contain polyisocyanurate
  • the carbon composite material is formed on the surface of the granular material.
  • thermosetting resin composition is a whole cathode.
  • the active material may comprise 5 to 25% by weight.
  • thermosetting resin composition is a polyol 100 to 250 parts by weight of the isocyanate compound may be included based on 100 parts by weight of the composition.
  • the poly-composition may include poly, an organic solvent, an additive, and a catalyst, and the solid content of the polyol composition may be 10 to 70 wt%.
  • the polyol is a polyether poly
  • polyester polyols Any one or more selected from polyester polyols, polytetramethylene ether glycol polyols, polyharnstoff dispersion (PHD) polyols, amine modified polyols, Manmich polyols and combinations thereof Can be chosen
  • the specific surface area is 5 to 10 m 2 / g; the average size of the surface micropores may be 1 to 2 nm.
  • a method for producing a negative electrode active material for a lithium secondary battery includes a) a granular material, a polyol composition,
  • thermosetting resin composition containing an isocyanate compound
  • the thermosetting resin composition includes the entire cathode.
  • a non-graphitizable S-emitting material having an average thickness of 3 to 30 nm is formed on the surface of the granular material, including 5 to 25 wt%.
  • step a) is performed at 10 ° C or less in a single screw kneader, twin screw mixer or batch kneader, and the drying and curing of step b) are performed in a chamber, It can be performed with heat and heat from 60 to 150 ° C in a device equipped with heat treatment and exhaust.
  • the heat treatment of step c) is a primary heat treatment and a secondary heat treatment.
  • the first heat treatment may be carried out at a temperature of 500 to 1,000 ° C
  • the second heat treatment may be carried out at a temperature of 900 to 1,500 ° C.
  • the step (d) of dismantling is performed by a circular rotor rotating by a motor, and at least two grinding bars are mounted on the rotating rotor, and the cross-sectional shape of the grinding bar is It can be processed with a crusher of circular to polygonal shape.
  • Lithium secondary battery containing a negative electrode active material for secondary batteries Lithium secondary battery containing a negative electrode active material for secondary batteries.
  • the non-reversible capacity of the lithium secondary battery is 10 to 31 mAh / g, 50 cycle capacity retention rate may be 90% or more.
  • the anode active material for a lithium secondary battery of the present invention and a method for manufacturing the lithium secondary battery using the same, according to the lithium secondary battery using the same, the granular material coated with a thermosetting resin composition is thermally treated in an inert gas atmosphere to contain a cathode active material including a carbonized carbon composite.
  • the non-graphitizable carbon layer derived from the thermosetting resin is uniformly formed, which has advantages in improving battery characteristics such as initial efficiency improvement, lifespan characteristics, layer discharge output, and low temperature storage characteristics.
  • the lithium secondary battery containing the negative electrode active material according to the present invention has an advantage of significantly improving not only the initial charge and discharge efficiency of the battery but also the 50-cycle capacity retention rate.
  • FIG. 1 (b) is a scanning electron microscope (SEM) photograph measuring the surface of a negative electrode active material prepared according to Example 1 of the present invention.
  • FIG. 2 is a graph of particle size distribution comparison of cathode active materials according to Comparative Example 6 and Example 1 of the present invention.
  • TEM images are transmission electron microscope (TEM) images of the surface of the negative electrode active material prepared according to Example 2, Comparative Example 1 and Comparative Example 2 of the present invention, respectively.
  • the granular material coated with the thermosetting resin composition is thermally carbonized under an inert gas atmosphere to form a thin and uniform non-graphitizable carbon layer derived from the thermosetting resin on the surface of the granular material.
  • the granular material according to an embodiment of the present invention is not limited, but may be a carbon-based material, a silicon-based material, or a polymer-based material that can be used as a negative electrode active material of lithium secondary battery.
  • the material is a carbon-based material, which may be a graphite granular material. More preferably, it may be selected from artificial graphite or natural graphite. Particularly, the carbon content is 80-98%, preferably 95% or more, and the average particle diameter is 1 ⁇ to 50 /.
  • One or more of natural crystalline graphite and natural crystalline graphite graphite can be selected.
  • thermosetting resin composition according to one embodiment of the present invention is a polyol composition
  • It contains an isocyanate compound and is hardened at the surface of the particulate material to form a polyurethane resin.
  • the polyurethane resin is contained in a polyol composition.
  • the polyurethane resin may also contain polyisocyanurate depending on the type and content of isocyanate compound.
  • Polyisocyanurate may be produced by endothermic reaction of isocyanate compounds, and may be promoted by catalysts, particularly basic catalysts, in the polyol composition.
  • thermosetting resin Through heat treatment of granular material coated with a thermosetting resin according to the present invention
  • the carbon composite produced by carbonization may be used as a negative electrode active material for lithium secondary batteries.
  • the carbon composite may include a non-graphitizable carbon layer derived from a polyurethane resin coated on a granular material surface. It is preferable that the thickness of is less than 40mn, and more preferably, 3 to 30nm is effective.
  • the polyol may be used for preparing a polyurethane resin.
  • One or more selected from amine-modified polyols, Manmich polyols and mixtures thereof is preferred, and more preferably
  • Polyester polyols, amine modified polyols, Manmich polyols or combinations thereof are effective.
  • the molecular weight of the polyol is not limited, but is 300 to 3,000 g / rn.
  • the molecular weight of poly When the molecular weight of poly is less than 300 g / mol, it is synthesized by the formation of monool. The thermal stability of polyurethane resin is deteriorated and melting occurs in the carbonization process. If the molecular weight of polyol exceeds 3,000 g / mol, the amorphous carbon chain increases in the poly structure and the thermal stability of polyurethane resin is increased. There is a risk of deterioration.
  • the isocyanate compound that reacts with the polyol is conventionally used in the manufacture of polyurethane resins.
  • HDI nucleated methylene diisocyanate
  • IPDI isophorone diisocyanate
  • H12MDI 4,4'-dicyclonuclear methane diisocyanate
  • TDI polyethylene polyphenyl isocyanate
  • TDI toluene diisocyanate
  • Diisocyanate TODI
  • NDI naphthaleneddiosocyanate
  • xylene naphthaleneddiosocyanate
  • One or two or more selected from diisocyanate (XDI), lysine diisocyanate (LDI) and triphenylmethane triisocyanate (TPTI) are preferred, and more preferably 4,4'-diphenylmethane diisocyanate (4, 4'-MDI, monomeric MDI), polymeric diphenylmethane diisocyanate (polymeric MDI) or polyethylene polyphenylisocyanate are effective.
  • the content of the isocyanate compound is less than 50 parts by weight, the formation of isocyanurate bonds, which enhance thermal stability, is insufficient. Similar to this graphitized carbon, the resin may be melted to reduce the shape stability of the coating layer.
  • isocyanurate bonds are excessively generated and carbonized. After the process, the specific surface area increases, which increases the water adsorption rate and may increase the initial surface area response during battery layer discharge.
  • the polyol composition according to one embodiment of the present invention may further include a catalyst for effectively inducing reaction of the polyol and isocyanate compound.
  • the chom JEfl —————————————————————————————————————
  • Examples include, but are not limited to, pentamethyldiethylene triamine, dimethyl cyclohexyl amine, bis- (2-dimethyl aminoethyl) ether Triethylene
  • the content of the catalyst according to one embodiment of the present invention is based on 100 parts by weight of the polyol.
  • the reaction of the isocyanate compound may proceed slowly so that the production efficiency of the cathode active material may decrease. If the catalyst content is more than 5 parts by weight, the reaction proceeds too fast, resulting in uneven polyurethane resin formation. As the surface becomes uneven, the properties of the cathode active material may be degraded.
  • the polyol composition according to one embodiment of the present invention may further include an organic solvent and an additive for improving processability.
  • the organic solvent is not limited as long as it is an organic solvent well known in the art, and examples thereof include aromatic hydrocarbons such as benzene, toluene, xylene and mesitylene, methyl ethyl ketone, acetone and methyl amyl ketone. And one or more kinds of alcohols such as ketones such as methyl isobutyl ketone and cyclonucleanone, ethanol, propanol, butanol, nusanol, cyclonucleool, ethylene glycol and glycerin can be selected.
  • aromatic hydrocarbons such as benzene, toluene, xylene and mesitylene, methyl ethyl ketone, acetone and methyl amyl ketone.
  • alcohols such as ketones such as methyl isobutyl ketone and cyclonucleanone, ethanol, propanol, butanol, nusanol, cyclonucle
  • the solids content of the poly-composition is not limited, but may be 10 to 70% by weight, and more preferably 10 to 60% by weight. If necessary, the amount of solvent can be adjusted to control the solids content of the polyol composition.
  • the solid content of the polyol composition is less than 10% by weight, there is a problem that a relatively large amount of organic solvent consumes energy that is unnecessary during drying and curing, and that the manufacturing cost may increase due to an increase in solvent usage.
  • the overall viscosity of the thermosetting resin composition may be too high to uniformly coat the surface of the granular material, and the viscosity increases, so that the liquid raw material of the thermosetting resin composition or the polyol composition is transferred to the pip. You may have difficulty
  • thermosetting resin composition is a whole cathode.
  • active materials it can contain 5 to 25% by weight. More preferably, it can contain 10 to 20% by weight ⁇ 3 ⁇ 4.
  • thermosetting resin composition When the content of the thermosetting resin composition is less than 5% by weight, it is difficult to exert the effect of improving the performance because the effect of coating is not hardened, and when the weight of the thermosetting resin composition is greater than 25% « 3 ⁇ 4, the non-graphitizable carbon layer is formed thick. Degradation of C-rate performance and necking of the carbon layers on the surface of the particles can cause problems in the yield of the product during the crushing process.In addition, the surface of the granular material is damaged due to the increase in the grinding energy requirements. As a result, the initial discharge efficiency may be drastically reduced.
  • a method of manufacturing a cathode active material for a lithium secondary battery is
  • thermosetting resin composition Mixing the thermosetting resin composition
  • thermosetting resin composition drying and curing the mixture of the thermosetting resin composition and the granular material
  • thermosetting resin Manufacturing a granular material coated with a thermosetting resin
  • thermosetting resin The granular material coated with the thermosetting resin under an inert gas atmosphere.
  • the mixing may simultaneously mix the granular material and the thermosetting resin composition, or the polyol composition and the granular material first, and the isocyanate compound may be added later. , It is not limited to this.
  • thermosetting resin composition is a whole cathode
  • the active material may contain 5 to 25% by weight, and when included in the content, it is possible to form a thin and uniform non-graphitizable carbon layer having an average thickness of 3 to 30 nm on the surface of the particulate material.
  • the mixing method is not limited, but may be performed at less than 10 o C in a single axis, biaxial, or batch type mixer. Preferably, it is performed at -20 to 10 ° C. This is effective because it can delay hardening and improve the kneading uniformity.
  • drying and curing may be performed by hot air heating of 60 to 150 ° C. in a device equipped with a chamber and an exhaust vent.
  • hot air dryer, air dryer, cake dryer and ring dryer can be exemplified.
  • the drying and curing may be hot air heating from 60 to 150 ° C.
  • the speed of the hot air may be from 3 to 15 m / sec, but is not limited thereto.
  • the heat treatment of step c) may be a primary heat treatment or a secondary heat treatment.
  • At least one of the heat treatment, the first heat treatment may be performed at a temperature of 500 to 1,000 ° C, the second heat treatment may be carried out at a temperature of 900 to 1,500 ° C.
  • the primary heat treatment or the secondary heat treatment may be performed alone or sequentially after the primary heat treatment, depending on the type and composition of the granular material and the thermosetting resin composition. Can be done with, but is not limited to.
  • the first heat treatment or the second heat treatment is performed under an inert gas atmosphere, and the inert gas is preferably made of helium, nitrogen, argon or a mixture thereof.
  • the first heat treatment step is preferably performed at 500 to 1,000 ° C, more preferably at 600 to 900 ° C. If the primary heat treatment is performed at less than 500 ° C, the low molecular weight gases will be less volatilized and remain in the material, which may reduce the yield of the product, and as a result of the residual gas generated in the secondary heat treatment step, Problems with contamination of the inside and the surface of the product may occur.
  • the secondary heat treatment temperature is preferably 900 to l, 400 o C, and more preferably 1,200 to l, 300 o C.
  • the remaining hydrogen in carbon reacts irreversibly with lithium ions, resulting in a decrease in battery capacity in the initial 5 cycles, and carbon at temperatures above 1,400 ° C.
  • the storage capacity or capacity of lithium ions decreases, the energy density decreases greatly during battery manufacturing, the specific surface area increases, and the property of adsorbing moisture in the air increases, resulting in reaction of lithium ions and moisture in the battery reaction.
  • electric furnaces must be replaced with heat-resistant materials that are more heat resistant than l, 400 o C. May occur.
  • the carbon composite material in step d), may be disintegrated using a rotary rotor type grinding machine.
  • step d) is performed to eliminate the fusion between the particles of the negative electrode active material after firing and to separate the particles into individual particles.
  • the disintegration process can be applied to any type of grinder, but preferably to the coating layer on the surface of the particle. It is advisable to apply a weak grinding method to prevent damage.
  • the grinding machine is rotated by a circular rotor that is rotated by a motor, and at least two grinding bars are mounted on the rotating rotor, and the cross-section of the grinding bar can be processed by a circular or polygonal grinding machine.
  • a circular rotor that is rotated by a motor
  • at least two grinding bars are mounted on the rotating rotor, and the cross-section of the grinding bar can be processed by a circular or polygonal grinding machine.
  • pin mills, fine impact mills, ball mills, bead mills, rotor-mounted air classifiers, dynomills, disc mills, roll mills and cyclone mills can be used in at least one and two or more combinations.
  • the use of a pin mill or fine impack miU is effective because it prevents surface damage of the carbon composite.
  • the specific surface area is from 5 to 10 m 2 / g, and the average size of the surface micropores can be from 1 to 2mn. Due to these characteristics, the non-reversible capacity of a lithium secondary battery according to the present invention is 10 to 31 mAh / g, 50 Since the cycle capacity retention rate can be 90% or more, the battery characteristics such as life characteristics, layer discharge output, and low temperature storage characteristics, as well as initial characteristics It is possible to provide a lithium secondary battery with significantly improved layer discharge efficiency and cycle capacity retention.
  • t-plot is used to analyze the pore size distribution, that is, t-plot can be used to determine the shape according to pore size.
  • Micropore Volume percent Micropore volume / Total pore volume * 100
  • the pores of the sample surface were analyzed by the sorbent gas gas adsorption method through an analyzer (Bellsorp mini ⁇ ).
  • the measuring cell was a coin-type half-cell with lithium metal foil as an electrode and a counter electrode with a cathode active material and a binder in a ratio of 97: 3, with an EC / DEC of 1: 1 as an organic electrolyte with a separator in between.
  • the layer charge is a lithium ion ion on the carbon electrode by the constant current method up to 0.005V at 0.1 C rate.
  • Lithium ion insertion was performed by constant current method starting from 0.005V, and the lithium ion insertion was terminated when the current became 0.01 mA.
  • the discharge was discharged from the carbon electrode with the final voltage of 1.5V by constant current method at 0.1C rate.
  • the ratio of the removal amount to the insertion amount was the initial efficiency, and the reversible capacity was calculated by converting the amount removed into weight equivalent capacity.
  • the evaluation of the output characteristics at room temperature is performed by measuring the output characteristics of lithium ion discharge at 25 ° C.
  • the three cycles were discharged at 0.2 C. Since then, the discharge (lithium ion tally) C rate was gradually increased by 0.2 C rate, and 5 C-rate reversible at 0 to the reversible capacity. The retention rate of the dose was measured.
  • Cheungjeon as the index is measured by the initial 0.1 C in the third cycle progression after 0.2 C discharge layer to the third layer discharge cycle in progress and after a 0 o C 0.2 C 0.2 C charge rocheung handed down phase contrast.
  • D50 is 18 population-type graphite graphite 20kg / hr in biaxial continuous shaker, polyol
  • the polyol (SSP-104HC, Aekyung Petrochemical Co., Ltd.) was simultaneously introduced with 1.3 kg / hr and acetone at 3.1 kg / hr in the composition, and then isocyanate (JG55K, Kumho Mitsui) was added to the middle part of the stirring tank during the stirring process. Chemical) at a rate of 2.5 kg / hr.
  • the temperature of the cooling jacket of the stirrer was set to -15 ° C. (The actual temperature of the dough inside the stirrer was measured at about 7 ° C.)
  • the drying process is a continuous conveyor belt type. Spherical graphite coated with a thermosetting resin, using a hot air dryer, the interior temperature of the dryer set to 80 ° C, and drying and curing reaction for 15 minutes.
  • Carbon composites were obtained.
  • the obtained carbon composites were first heat-treated at 700 ° C. in a nitrogen atmosphere and secondly heat-treated at 1250 ° C. to prepare a negative electrode active material having a flame retardant carbon layer having a thickness of about 15 nm.
  • the physical properties of the negative electrode active material are measured and shown in Table 2.
  • the carbonization yield of non-graphitizable carbon is set to 34% to determine the amount of polyol and isocyanate.
  • a negative electrode active material was prepared in the same manner as in Example 1, except that 0.8 kg / hr, acetone was added at 4.6 kg / hr, and an isocyanate (JG55K, Kumho Mitsui Chemicals) was 1.6 kg / hr.
  • the physical properties of the active material were measured and shown in Table 2 below.
  • D50 was prepared in the same manner as in Example 1 except that 12 population-type graphite was used to prepare a cathode active material. Burned out.
  • a negative electrode active material was prepared in the same manner as in Example 1 except that D50 used 10; ⁇ population-type natural graphite. The physical properties of the prepared negative electrode active material were measured. 2 is shown.
  • a negative electrode active material was prepared in the same manner as in Example 1 except that the physical properties of the prepared negative electrode active materials were measured and shown in Table 2 below.
  • the impeller mixer was used for the kneading process.
  • a negative electrode active material was prepared in the same manner as in Example 1 except that physical properties of the prepared negative electrode active material were measured and shown in Table 2 below.
  • the drying process was the same as in Example 1 except that the chamber type continuous hot air dryer was used and the speed of the hot air was adjusted to 3 m / sec.
  • the negative electrode active material was prepared. The physical properties of the prepared negative electrode active material were measured and shown in Table 2 below.
  • the drying process was carried out in the same manner as in Example 1, except that the drying process was performed using an intermittent hot air drying furnace. Burned out.
  • the D50 is 18 populations in an impeller stirrer.
  • a graphite pitch composite with uniform pitch distribution was prepared by mixing 10 kg of natural graphite with a yield of 65% and an average particle diameter of about 2 ⁇ m.
  • the first heat treatment was performed at 700 ° C.
  • the second heat treatment was performed at 1250 ° C. to prepare a cathode active material having a carbonaceous carbon layer.
  • the precursor of the carbon dioxide was introduced at a carbonization yield of 64%.
  • a negative electrode active material was prepared in the same manner as in Example 1, except that 0.3 kg / hr, acetone was 6.2 kg / hr, and an isocyanate (JG55K, Kumho Mitsui Chemicals) was charged at a rate of 0.5 kg / hr.
  • the physical properties of the active material were measured and shown in Table 2 below.
  • a negative electrode active material was prepared in the same manner as in Example 1 except that 2.3 kg hr, acetone was added at 4.0 kg / hr and isocyanate (JG55K, Kumho Mitsui Chemicals) at a rate of 0.7 kg hr. Physical properties were measured and shown in Table 2 below.
  • a negative electrode active material was prepared in the same manner as in Example 1, except that 0.8 kg / hr, acetone was added at a rate of 3.9 kg / hr and an isocyanate (JG55K, Kumho Mitsui Chemicals Co., Ltd.) at a rate of 2.3 kg / hr.
  • the physical properties of the active material were measured and shown in Table 2 below.
  • Natural graphite was used as it is, and the physical properties were shown in Table 2 below.
  • FIG. 1 (a) shows a scanning electron microscope (SEM) photograph of the surface graphite of natural graphite used in Comparative Example 6 of the present invention
  • FIG. 1 (b) is manufactured according to Example 1 of the present invention.
  • a uniform flame retardant carbon layer can be formed.
  • FIG. 2 is a graph of particle size distribution comparison of a cathode active material according to Comparative Example 6 and Example 1 of the present invention.
  • FIG. 2 is a graph of particle size distribution comparison of a cathode active material according to Comparative Example 6 and Example 1 of the present invention.
  • TEM images are transmission electron microscope (TEM) images of the surface of the negative electrode active material prepared according to Example 2, Comparative Example 1 and Comparative Example 2 of the present invention, respectively.
  • the cathode active material manufactured according to one embodiment of the present invention.
  • the thickness of the non-graphitizable coating layer is uniformly coated between 3 and 30 nm.
  • Comparative Example 1 where the pitch was coated, there was an uncoated area and the thickness deviation was 0 to 0. It was found to be uneven at 8 nm.
  • Table 2 is a table showing the results of the specific surface area and pore analysis of the cathode active material according to the Examples and Comparative Examples of the present invention. Referring to Table 2, a cathode having a non-graphitizable coating layer according to an embodiment of the present invention is formed. It can be seen that the specific surface area of the active material is significantly increased compared to the raw material of Comparative Example 6. Further, it can be seen that the average size of the surface micropores is uniformly distributed in the range of 1 to 2mn.
  • the negative electrode active material according to the present invention has a large specific surface area in view of the results of Table 2 above.
  • the micropore size of about lnm is so small that the problem described above has been solved.
  • the moisture content after 1 hour after the preparation of the cathode active material in the Examples and Comparative Examples shown in Table 2 is referred to as non-graphitizable carbon.
  • the negative electrode active material of the present invention which is temporarily coated, exhibits the same or lower moisture content than that of Comparative Example 1 with pitch coated.
  • CMC Carboxyl Methyl Cellulose
  • distilled water was added and uniformly stirred in the form of sludge and uniformly coated on the copper foil.
  • the coating was uniformly coated at 110 ° C. using a doctor blade. Drying was performed at 60 ° C. for 30 minutes and press was performed at a pressure of 0.6 MPa.
  • the electrode on the foil was punched into a circular shape of 1 cm 2 and dried in a 120 ° C. vacuum oven for 12 hours.
  • lithium secondary battery is used as a counter electrode to construct a lithium secondary battery. The characteristics were evaluated.
  • the lithium secondary battery is a coin-type battery of 2016 size (diameter 20mm, thickness 16mm).
  • layer discharge was performed at 25 C by the constant current-constant voltage method (CCCV) using a ⁇ sub-charge discharge test apparatus manufactured by TOYO SYSTEM.
  • CCCV constant current-constant voltage method
  • 'layered' is a reaction in which the voltage of the coin cell is lowered by the reaction of lithium being inserted into the cathode
  • 'discharge' is a reaction in which the lithium battery is detached from the cathode and moved toward the counter electrode, and the voltage of the coin-type battery is increased.
  • the constant current-constant voltage condition is performed by layering at a constant current density (0.1C standard) until the voltage of the coin-type battery reaches 0.005V, and then decreases uniformly until the current value reaches 0.05mA while maintaining the voltage.
  • the amount of electricity supplied is divided by the increase in the amount of the cathode active material of the electrode, which is called the layer capacity per unit weight of the cathode active material (mAh / g).
  • the discharge was caused by the voltage of the coin cell A constant current was conducted until 1.5V, and the value of the discharged electric power divided by the increase in the amount of the negative electrode active material of the electrode was called the discharge capacity per unit weight of the negative electrode active material (mAh / g).
  • Reversible capacity is defined as discharge capacity, and non-reversible capacity is determined from floor capacity
  • the discharge capacity was calculated by subtracting the discharge capacity, and the discharge capacity was calculated as a percentage ( ⁇ ) compared to the effective silver layer capacity.
  • the characteristic value of the basic coin-type battery was shown by averaging the characteristic values of three or more identical batteries made of the same sample.
  • the high-rate charge-discharge characteristics of the assembled lithium secondary battery were performed at 25 0 C by the constant current-constant voltage method (CCCV), the same as in (c). To increase or decrease the constant current density supplied or discharged cycle-by-cycle, and then discharge to the measured capacity (mAh / g). Indicated.
  • CCCV constant current-constant voltage method
  • the cathode active materials according to Examples 4 and 5 show the same initial efficiency as in Example 1 even when spherical natural graphite having different particle diameters is used.
  • thermosetting resin coating was 34.48% as in Comparative Example 2 or 3.44% as in Comparative Example 3, the initial efficiency was improved, but the effect was not relatively large.
  • the capacity retention rate of the lithium secondary battery using the negative electrode active material according to Example 2 was superior to that of Comparative Example 1 with pitch coating.
  • the room temperature capacity maintenance rate according to C-rate is similar to the capacity maintenance rate according to the cycle.
  • the higher the amount of thermosetting resin coating the better the characteristics.However, in Comparative Example 2 having a thermosetting resin coating amount of 34.48%, the temperature retention rate of C-rate for heat was 17.58% compared to that of Example 1. .
  • the isocyanate ratio in Table 1 represents the addition ratio (%) to the weight of the isocyanate compound based on 100 parts by weight of poly. As shown in Table 3, the isocyanate ratio is 100 to At 250 parts by weight, that is, 100 to 250%, the initial efficiency improvement effect is noticeable.

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Abstract

본발명은 리튬이차전지용 음극 활물질 및그 제조방법, 이를 이용한 리튬 이차전지에 관한 것으로, 보다 구체적으로는 우수한 수명 특성, 충방전 출력, 고온저장특성 등의 전지 특성을 향상시킨 리튬이차전지용 음극활 물질 및 그 제조방법, 이를 이용한 리튬이차전지에 관한 것이다.

Description

명세서
발명의명칭:리튬이차전지용음극활물질및그제조방법，이를 이용한리튬이차전지
기술분야
[1] 발명은리튬이차전지용음극활물질및그제조방법,이를이용한
리튬이차전지에관한것으로,보다구체적으로는우수한수명특성,층방전 출력，고온저장특성등의전지특성을향상시킨리튬이차전지용음극활물질및 그제조방법，이를이용한리튬이차전지에관한것이다.
배경기술
[2] 최근리튬이차전지는친환경그린카에대한관싶과수요가높아지고있는 가운데전기모터로구동되는전기자동차의전원으로각광받고있다.뿐만 아니라，소형전자기기분야에서도스마트폰，태블릿 PC및울트라북등의 전자기기의기술발전에힘입어그활용도가점점넓어지고있다.
[3] 최근리튬이차전지의사용분야가점점넓어지고소비자의요구도다양해짐에 따라기존의리튬이차전지에비해더높은성능이요구되고있다.현재리튬 이차전지용음극활물질의대부분은흑연계활물질로이루어져있으며,전지의 사이즈가대형화되는추세에따라전지의가격경쟁력이상업적으로중요한 요소가되면서전지용소재도가격경쟁력이중요하게되었다.따라서，음극 활물질은흑연계중에서도가격경쟁력이있는탄소계활물질의점유율이점점 높아지고있는추세이다.그러나천연흑연은인조혹연에비해층간거리및 비표면적이넓고，결정구조의결함및인편상의입자형태둥의요인으로 인하여,전지용활물질로사용되었을때전해액과의부반웅이심해지거나, 전극에서흑연결정배향성이높아져출력성능이현저히저하되는문제점을 가지고있었다.
[4] 이러한문제점을해결하기위하여,천연흑연을구형화하거나표면을개질하는 등의기술을개발하였다.종래천연혹연의표면을개질하는방법으로석유계 또는석탄계피치로피복한후소성하는방법을사용하고있다.그러나，이러한 방법은피치의코팅공정이고상공정인관계로균일한피복자체가어려우며 , 균일피복이되었더라도피치의열가소성특성으로인하여소성공정중에 피치가녹아흘러내림으로써상부층과하부층의피치농도불균일이발생할 가능성이높고이로인하여흑연표면에피복된탄소층의두께균일성을 확보하기어렵다.탄소층두께의균일성이확보되지않을경우，전해액과흑연 엣지면과의전해액분해반웅에의한 SEI(solid electrolyte interphase)층을형성할 수있다.또한，폴리프로필렌유기용매를사용한비수계리튬 2차전지의경우， 혹연의반데르발스층사이로리튬이온과더불어폴리프로필렌분자가 침투하여혹연의박리현상을일으켜결과적으로이차전지의초기효율저하, 수명저하및출력성능저하등의제반성능열화로이어지는문제점이 남아있었다.
[5] 대한민국공개특허제 10-2014-0140323호 (특허문헌 1)에는구형흑연올
포함하는코어부표면에석유계피치,석탄계피치，저분자중질유등에서 선택되는저결정성입상소재로피복하여형성하는리튬이차전지용음극 활물질에관하여개시하고있다.그러나,이경우，일부비가역반웅을억제하는 효과는나타났으나，구형흑연표면에피복된저결정성입상소재가소성공정 중에흘러내려균일한피복이어려운문제가대두되었으며，쉽게흑연
박리현상이발생하여리튬이차전지의물성이저하되는문제가여전히남아 있었다ᅳ
[6] 따라서,리튬이차전지의비가역반웅을억제하면서,초기효율,내용제성및 전지출력특성이우수한리튬이차전지용음극활물질의개발이요구되고있다.
[7] [선행기술문헌]
[8] (특허문헌 1)대한민국공개특허제 10-2014-0140323호 (2014.12.09)
발명의상세한설명
기술적과제
[9] 본발명은종래의문제점을해결하기위한것으로，천연흑연의표면에
열경화성수지를균일하게코팅한후경화시켜열경화성수지층을형성한후 이를열처리하여탄소화함으로써,열경화성수지유래난흑연화성탄소가 피복된천연흑연계음극활물질을고안함으로써초기효율,내용제성，전지 출력특성및수명특성이우수한리튬이차전지용음극활물질및그제조방법을 제공하는것을목적으로한다.
[10] 또한，상술한리튬이차전지용음극활물질을포함하는리튬이차전지를
제공하는것을목적으로한다.
과제해결수단
[11] 상기와같은목적을달성하기위한본발명에따르면，폴리을조성물및
이소시아네이트계화합물을포함하는열경화성수지조성물이코팅된탄소계 입상소재를비활성기체분위기하에서열처리하여탄소화시킨탄소복합체를 포함하는리튬이차전지용음극활물질에관한것이다.
[12] 본발명의일실시예에따르면,상기열경화성수지조성물은상기입상소재의 표면에서경화되어폴리우레탄수지를형성하며，상기폴리우레탄수지는 폴리이소시아누레이트를함유할수있다.
[13] 본발명의일실시예에따르면,상기탄소복합체는상기입상소재표면에
평균두께 3내지 30mn의난흑연화성탄소층을형성시킬수있다.
[14] 본발명의일실시예에따르면，상기열경화성수지조성물은전체음극
활물질에대하여 , 5내지 25중량 %를포함할수있다.
[15] 본발명의일실시예에따르면,상기열경화성수지조성물은상기폴리올 조성물 100증량부에대하여，이소시아네이트계화합물을 100내지 250중량부 포함할수있다.
[16] 본발명의일실시예에따르면，상기폴리을조성물은폴리을,유기용매，첨가제 및촉매를포함하며,상기폴리올조성물의고형분함량이 10내지 70중량%일 수있다. '
[17] 본발명의일실시예에따르면,상기폴리올은폴리에테르계폴리을,
폴리에스테르계폴리올，폴리테트라메틸렌에테르글리콜폴리올，피에이치디 폴리을 (Polyharnstoff Dispersion(PHD) polyol),아민 (Amine)변성폴리올, 만니히 (Manmich)폴리을및이들의흔합물중에서선택되는어느하나또는둘 이상이선택될수있다ᅳ
[18] 본발명의일실시예에따르면,상기이소시아네이트계화합물은
핵사메틸렌디이소시아네이트，이소포론디이소시아네이트，
4,4'-디시클로핵실메탄디이소시아네이트，폴리에틸렌폴리페닐
이소시아네이트,롤루엔디이소시아네이트, 2,2—디페닐메탄디이소시아네이트, 2,4-디페닐메탄디이소시아네이트, 4,4'-디페닐메탄디이소시아네이트，폴리머릭 디페닐메탄디이소시아네이트，오르토를루이딘디이소시아네이트,나프탈렌 디이소시아네이트,크실렌디이소시아네이트,라이신디이소시아네이트및 트리페닐메탄트리이소시아네이트증에서선택되는어느하나또는둘이상이 선택될수있다.
[19] 본발명의일실시예에따르면，비표면적이 5내지 10 m2/g이고;표면마이크로 기공의평균크기가 1내지 2nm일수있다.
[20] 또한,상기와같은목적을달성하기위한본발명에따르면,리튬이차전지용 음극활물질의제조방법에대하여， a)입상소재와폴리올조성물과
이소시아네이트계화합물을포함하는열경화성수지조성물을흔합하는단계; b)상기열경화성수지조성물과입상소재의혼합물을건조및경화시켜 열경화성수지가코팅된입상소재를제조하는단계; c)상기열경화성수지가 코팅된입상소재를비활성기체분위기하에서열처리하여탄소화시킨 탄소복합체를제조하는단계;및 d)상기탄소복합체를해쇄하는단계;를 포함하며,상기열경화성수지조성물은전체음극활물질에대하여， 5내지 25 중량 %를포함하여，상기입상소재표면에평균두께 3내지 30nm의난흑연화성 S소출ᅳ을—형^ -하 뫼—튬ᅳ아차쟌자용ᅳ음-극ᅳ활—물질ᅳ의-제조방 -법에—관한ᅳ것이 -타^ᅳ—
[21] 본발명의일실시예에따르면，상기 a)단계의흔합은일축혼련기，이축흔련기 또는배치식흔련기에서 10°C이하에서수행하며，상기 b)단계의건조및경화는 챔버,열처리부및배기구가구비된장치에서 60내지 150°C의열 Ϋ가열로 수행될수있다.
[22] 본발명의일실시예에따르면，상기 c)단계의열처리는 1차열처리및 2차
열처리중에서적어도하나를포함하고,상기 1차열처리는 500내지 1,000°C 온도에서，상기 2차열처리는 900내지 1,500°C온도에서진행할수있다. [23] 본발명의일실시예에따르면,상기 d)해쇄하는단계는모터에의해회전하는 원형로터에의해회전하고，회전로터에적어도 2개이상의분쇄바가장착되어 있으며，분쇄바의단면형상은원형내지는다각형인형태의분쇄기로처리할수 있다.
[24] 또한,상기와같은목적을달성하기위한본발명에따르면,상술한리튬
이차전지용음극활물질을포함하는리튬이차전지에관한것이다.
[25] 본발명의일실시예에따르면,상기리튬이차전지의비가역용량은 10내지 31mAh/g이며 , 50회사이클용량유지율이 90%이상일수있다.
발명의효과
[26] 본발명의리튬이차전지용음극활물질및그제조방법，이를이용한리튬 이차전지에따르면,열경화성수지조성물이코팅된입상소재를비활성기체 분위기하에서열처리하여탄소화한탄소복합체를포함하는음극활물질을 제조함으로써，열경화성수지로부터유도되는난흑연화성탄소층이균일하게 형성되어초기효율향상,수명특성，층방전출력，저온저장특성등의전지 특성을향상시킬수있는장점이있다.
[27] 또한，본발명에따른음극활물질을포함하는리튬이차전지는전지의초기 충방전효율뿐만아니라 50회사이클용량유지율이현저히향상되는장점이 있다.
도면의간단한설명
[28] 도 1(a)는본발명의비교예 6에사용된천연혹연의표면을측정한
주사전자현미경 (SEM)사진올나타낸것이며，도 1(b)는본발명의실시예 1에 따라제조된음극활물질의표면을측정한주사전자현미경 (SEM)사진이다.
[29] 도 2는본발명의비교예 6및실시예 1에따른음극활물질의입도분포비교 그래프이다.
[30] 도 3내지도 5는각각본발명의실시예 2，비교예 1및비교예 2에따라제조된 음극활물질의표면을측정한투과전자현미경 (TEM)사진이다.
발명의실시를위한형태
[31] 이하,본발명의리튬이차전지용음극활물질및그제조방법에대하여
바람직한 시형태및평가시험항목을상세히설명한다.본발명은하기의 실시예에 하여보다더잘이해될수있으며，하기의실시예는본발명의예시 목적을위한것이고，첨부된특허청구범위에의하여한정되는보호범위를 제한하고자하는것은아니다.
[32]
[33] 리튬이차전지용음극활물질을제조하기위하여，열경화성수지조성물이 코팅된입상소재를비활성기체분위기하에서열처리하여탄소화함으로써， 입상소재표면에열경화성수지로부터유도되는난흑연화성탄소층을얇고 균일하게형성하여초기효율，수명특성,층방전출력,저온저장특성，사이클 용량유지율등의전지특성을향상시킬수있음을발견하여본발명을완성하게 되었다.
[34]
[35] 본발명의일실시예에따른입상소재는제한되지않으나，리튬이차전지의 음극활물질로사용될수있는탄소계소재,실리콘계소재및원료가되는 고분자계소재일수있다.예를들면，상기입상소재는탄소계소재로흑연성 입상소재일수있다.보다바람직하게인조흑연또는천연흑연에서선택될수 있다.특히，탄소함량이 80 - 98%,좋게는 95%이상이고,평균입경이 1Ό내지 50//m인천연결정질흑연및천연결정맥상흑연중에서 1종이상이선택될수 있다.
[36]
[37] 본발명의일실시예에따른열경화성수지조성물은폴리올조성물및
이소시아네이트계화합물을포함하며,상기입상소재의표면에서경화되어 폴리우레탄수지를형성할수있다.
[38] 본발명의일실시예에따른상기폴리우레탄수지는폴리올조성물내에
함유된폴리올및이소시아네이트계화합물의반응에의하여형성될수있다. 또한,상기폴리우레탄수지는이소시아네이트계화합물의종류및함량에 따라폴리이소시아누레이트를함유할수있다.
[39] 폴리이소시아누레이트는이소시아네이트계화합물의흡열반응으로생성될수 있으며，상기폴리올조성물내에촉매，특히,염기성촉매에의해촉진될수 있다.
[40] 본발명에따른열경화성수지가코팅된입상소재의열처리를통하여
탄소화함으로써생성되는탄소복합체를리튬이차전지용음극활물질로사용할 수있다.상기탄소복합체는입상소재표면에코팅된폴리우레탄수지로부터 유도되는난흑연화성탄소층을포함할수있다.상기난흑연화성탄소층의 두께는 40mn미만인것이바람직하고，보다바람직하게 3내지 30nm인것이 효과적이다.
[41] 본발명의일실시예에따르면,상기폴리올은폴리우레탄수지제조에
사용되는통상적인것으로특별히한정하지는않는다.구체적으로는
폴리에테르계폴리을，폴리에스테르계폴리을，폴리테트라메틸렌에테르 글-리 -콜-폴의ᅭ올—，—피 -쉐—이치괴—폴—리―올 -(Polyhamstoffᅳ Dis
아민 (Amine)변성폴리올,만니히 (Manmich)폴리올및이들의혼합물중에서 선택되는어느하나또는둘이상이바람직하며，보다바람직하게는
폴리에스테르폴리올,아민 (Amine)변성폴리올，만니히 (Manmich)폴리올또는 이들의흔합물이효과적이다.
[42] 상기폴리올의분자량은제한되지않으나， 300내지 3,000g/rn이인것이
바람직하고,보다바람직하게는 400내지 l,500g/m이인것이효과적이다.
폴리을의분자량이 300g/mol미만일경우에는모노올의형성으로합성된 폴리우레탄수지의열안정성이저하되어탄화공정에서용융이발생하는단점이 있으며，폴리올의분자량이 3,000g/mol을초과할경우에는，폴리을구조내에 비정질탄소사슬이증가하여폴리우레탄수지의열안정성이저하될우려가 있다.
[43] 본발명의일실시예에따르면，상기폴리올과반웅하는이소시아네이트계 화합물은폴리우레탄수지제조에사용되는통상적인것으로특별히
한정하지는않는다.구체적으로는핵사메틸렌디이소시아네이트 (HDI), 이소포론디이소시아네이트 (IPDI),
4，4'-디시클로핵실메탄디이소시아네이트 (H12MDI)，폴리에틸렌플리페닐 이소시아네이트，톨루엔디이소시아네이트 (TDI), 2,2-디페닐메탄
디이소시아네이트 (2,2'-MDI), 2,4-디페닐메탄디이소시아네이트 (2,4'-MDI),
4,4'-디페닐메탄디이소시아네이트 (4,4'-MDI,monomeric MDI),폴리머릭 디페닐메탄디이소시아네이트 (polymeric MDI),오르토를루이딘
디이소시아네이트 (TODI),나프탈렌디오소시아네이트 (NDI),크실렌
디이소시아네이트 (XDI),라이신디이소시아네이트 (LDI)및트리페닐메탄 트리이소시아네이트 (TPTI)중에서선택되는어느하나또는둘이상이 바람직하며 ,보다바람직하게는 4，4'-디페닐메탄디이소시아네이트 (4,4'-MDI, monomeric MDI),폴리머릭디페닐메탄디이소시아네이트 (polymeric MDI)또는 폴리에틸렌폴리페닐이소시아네이트가효과적이다.
[44] 상기폴리올과이소시아네이트계화합물의흔합비율은상기폴리을 100
중량부에대하여상기이소시아네이트계화합물이 50내지 250증량부포함하는 것이효과적이다.이소시아네이트계화합물의함량이 50중량부미만일 경우에는열안정성을높여주는이소시아누레이트결합의형성이층분하지 못하여,탄소화공정시이흑연화성탄소와유사하게레진이용융되어코팅층의 형상안정성이저하되는문제가발생할수있다.또한，이소시아네이트의함량이 250중량부초과일경우에는이소시아누레이트결합이과도하게생성되어, 탄소화공정후비표면적이증가되고이에따라수분흡착율이높아지고 전지층방전시초기표면부반웅이증가될우려가있다.
[45] 본발명의일실시예에따른상기폴리올조성물은폴리올과이소시아네이트계 화합물의반웅을효과적으로유도하기위해촉매를더포함할수있다.상기 촘 JEfl—는—당해 _zl_술ᅵ ^ _자_명ᅳ하 _계_공지ᅵ된ᅳ폴—라우웨-탄ᅳ합성ᅵ용-촉째-아면
제한되지않는다.예를들면，펜타메틸디에틸렌트리아민 (pentamethyldiethylene triamine)，디메틸사이클로핵실아민 (dimethyl cyclohexyl amine),비스 -(2-디메틸 아미노에틸)에테르 (Bis-(2-dimethyl aminoethyl)ether),트리에틸렌
디아민 ((triethylene diamine)포타슘옥토에이트 (potassium octoate),
트리스 (디메틸아미노메틸)페놀 (tris(dimethylaminomethyl)phenol),포타슘 아세테이트 (potassium acetate)또는이들의흔합물중에서선택된어느하나또는 둘이상을사용할수있다. [46] 본발명의일실시예에따른상기촉매의함량은폴리올 100중량부에대하여
0.1내지 5증량부첨가하는것이바람직하며,보다바람직하게 0.5내지 3중량부 첨가하는것이폴리우레탄수지와폴리시아누레이트수지가적절히형성될수 있어효과적이다.촉매의함량이 α 1증량부이하일경우는폴리올과
이소시아네이트계화합물의반웅이너무느리게진행되어음극활물질 제조효율이감소하는문제가발생할수있으며，촉매의함량이 5중량부초과일 때는반웅이너무빠르게진행되어폴리우레탄수지가불균일하게형성되고, 입상소재의표면이불균일해짐에따라음극활물질의물성이저하되는문제가 발생할수있다.
[47] 본발명의일실시예에따른폴리올조성물은가공성향상을위하여유기용매 및첨가제를더포함할수있다.
[48] 상기유기용매는당해기술분야에자명하게공지된유기용매이면제한되지 않으며，예를들면，벤젠,를루엔,크실렌，메시틸렌등의방향족탄화수소류, 메틸에틸케톤,아세톤,메틸아밀케톤,메틸이소부틸케톤，시클로핵사논등의 케톤류，에탄올，프로판올,부탄올,핵사놀，시클로핵산올,에틸렌글리콜, 글리세린등의알코올류중에서 1종또는 2종이상선택할수있다.
[49] 본발명의일실시예에따르면,상기폴리을조성물의고형분함량은제한되지 않으나 10내지 70증량 %일수있으며,보다바람직하게 10내지 60중량%일수 있다.흔련공정의타입에따라점도를조절할필요가있을시용매의양을 가감하여폴리올조성물의고형분함량을제어할수있다.
[50] 상기폴리올조성물의고형분의함량이 10중량 %미만일경우에는상대적으로 유기용매의함량이많아건조및경화시불필요한에너지가소비되는문제가 있으며，용매사용량증가에따라제조단가가상승할우려가있다.또한,고형분 함량이 70중량 %초과일경우에는전체적인열경화성수지조성물의점도가 너무높아입상소재표면에균일하게코팅되지않을수있으며，점도가높아져 열경화성수지조성물또는폴리올조성물의액상원료를핍프로이송하는데 어려움이있을수있다.
[51] 본발명의일실시예에따르면,상기열경화성수지조성물은전체음극
활물질에대하여 , 5내지 25중량 %포함할수있다.더욱바람직하게 10내지 20 중량 <¾포함할수있다.
[52] 상기열경화성수지조성물의함량이 5중량 %미만일경우에는코팅에의한 효과가두드러지지않아성능개선효과를발휘하기어려우며， 25중량 «¾초과일 경우에는난흑연화성탄소층이두껍게형성되어 C-rate성능저하및입자표면의 탄소층이서로붙는현상 (necking)으로인해해쇄공정시제품의수득률이 저하되는문제가발생할수있다.또한,해쇄시분쇄에너지요구량증가로 입상소재의표면이손상되어초기층방전효율이급격히저하될우려가있다.
[53]
[54] 다음으로，리튬이차전지용음극활물질의제조방법에관하여상세히 설명한다.
[55] 본발명의일실시예에따른리튬이차전지용음극활물질의제조방법은
[56] a)입상소재와폴리올조성물과이소시아네이트계화합물을포함하는
열경화성수지조성물을흔합하는단계;
[57] b)상기열경화성수지조성물과입상소재의흔합물올건조및경화시켜
열경화성수지가코팅된입상소재를제조하는단계;
[58] c)상기열경화성수지가코팅된입상소재를비활성기체분위기하에서
열처리하여탄소화시킨탄소복합체를제조하는단계;및
[59] d)상기탄소복합체를해쇄하는단계 ;를포함할수있다.
[60] 본발명의일실시예에따르면, a)단계에서상기흔합은입상소재와열경화성 수지조성물을동시에흔합하거나，상기폴리올조성물과입상소재를먼저 흔합하고，이소시아네이트계화합물을추후에투입할수있으나，이로제한되는 것은아니다.
[61] 본발명의일실시예에따르면,상기열경화성수지조성물은전체음극
활물질에대하여 , 5내지 25중량 %를포함할수있으며,상기함량으로포함할 때,상기입상소재표면에평균두께 3내지 30nm의얇고균일한난흑연화성 탄소층을형성할수있다.
[62] 본발명의 a)단계에서，흔합방법은제한되지않으나，일축흔련기，이축흔련기 또는배치식흔련기에서 10oC이하에서수행될수있다.바람직하게는 -20내지 10°C에서수행되는것이경화를지연시키고혼련균일도를향상시킬수 있으므로효과적이다.
[63] 본발명의일실시예에따른상기 b)단계에서건조및경화는챔버및배기구가 구비된장치에서 60내지 150oC의열풍가열로수행될수있다.
[64] 상기챔버및배기구가구비된장치는당해기술분야에자명한장치로
제한없이적용될수있으며，열풍건조기,기류건조기, cake dryer,링드라이어 등이예시될수있다.
[65] 상기건조및경화는 60내지 150°C의열풍가열일수있으며,열풍의속도는 3 내지 15m/sec일수있으나,이로제한되는것은아니다.
[66] 본발명의일실시예에따른상기 c)단계의열처리는 1차열처리또는 2차
열처리중에서적어도하나를포함하고，상기 1차열처리는 500내지 1,000°C 온도에서 ,상기 2차열처리는 900내지 1,500°C온도에서진행할수있다.
[67] 본발명에서요구하는음극활물질의물성을달성하기위하여입상소재및 열경화성수지조성물의종류및조성에따라 1차열처리또는 2차열처리를 단독으로수행하거나， 1차열처리후 2차열처리를순차적으로수행할수 있으며，이에제한되는것은아니다.
[68] 상기 1차열처리또는 2차열처리는비활성기체분위기하에서수행되며， 비활성기체는헬륨，질소,아르곤또는이들의혼합가스를사용하는것이 바람직하다. [69] 본발명의일실시예에따르면，상기 1차열처리단계는 500내지 1,000°C에서 수행되는것이바람직하며，보다바람직하게는 600내지 900oC에서수행되는 것이효과적이다. 1차열처리를 500°C미만에서수행할경우,저분자량가스들의 휘발이덜됨으로써재료내부에잔류하게되고,이로인해제품의수득률이 감소될수있으며 , 2차열처리단계에서발생되는잔여가스로인하여전기로 내부와제품표면을오염시키는문제가발생할수있다ᅳ또한, 1차열처리를
1,000°C초과하여수행할경우필요이상의열량공급으로제조비상승의원인이 되며,높은온도로인하여원료에서배출된타르가스의열분해생성물로제품의 오염이발생하는문제가있다.
[70] 본발명의일실시예에따르면，상기 2차열처리온도는 900내지 l,400oC가 바람직하며 ,보다바람직하게는 1,200내지 l,300oC가효과적이다. 1,000°C 미만의온도에서탄소화할경우에는，탄소내의잔류하는수소가리튬이온과 비가역적으로반응하여초기 5사이클정도에서전지의용량저하가발생하는 문제가있으며, 1,400°C초과의온도에서탄소화할경우에는,리튬이온의 저장능력인가역용량이감소하여전지제조시에너지밀도가크게저하되고, 비표면적이증가하여대기중의수분을흡착하는성질이증가함으로써，전지 반응에서리튬이온과수분이반웅하여비가역용량을증가시킬수있는문제가 발생한다.또한상업적인측면에서도전기로가 l,400oC이상의열처리은도를 견디기위해서는전기로의재질및구성이열에강한소재로바뀌어야하므로 제조비용및공정비용이상승하는문제가발생할수있다.
[71] 본발명의일실시예에따르면，상기 d)단계는상기탄소복합체를회전식로터 방식의분쇄기를이용해해쇄할수있다.
[72] 상기 d)단계의해쇄는소성후의음극활물질입자간융착현상을해소하여 낱개의입자로분리하기위하여수행하는공정이다.해쇄공정은일반적인 분쇄기라면어떤것이라도적용가능하지만가급적입자표면의코팅층의 손상을방지하기위해약한분쇄방법을적용하는것이바람직하다.
[73] 상기분쇄기는모터에의해회전하는원형로터에의해회전하고，회전로터에 적어도 2개이상의분쇄바가장착되어있으며，분쇄바의단면형상은원형 내지는다각형인형태의분쇄기로처리할수있다.예를들면,핀밀, fine impact mill,볼밀，비즈밀，로터가장착된기류방식의분급기，다이노밀,디스크밀,롤밀 및사이클론밀중적어도 1개및 2개이상의조합으로사용가능하다.보다 바람직하게는핀밀또는 fine impack miU을사용하는것이탄소복합체의표면 손상을방지할수있으므로효과적이다.
[74] 본발명의상술한제조방법으로제조된리튬이차전지용음극활물질은
비표면적이 5내지 10 m2/g이고,표면마이크로기공의평균크기가 1내지 2mn일 수있다.이러한특성으로인하여,본발명에따른리튬이차전지의비가역 용량은 10내지 31mAh/g이며, 50회사이클용량유지율이 90%이상일수 있으므로,수명특성,층방전출력，저온저장특성등의전지특성뿐아니라,초기 층방전효율및사이클용량유지율이현저히향상된리튬이차전지를제공할수 있다.
[75]
[76] 이하，본발명의리튬이차전지용음극활물질및이의제조방법에대하여 바람직한실시형태및물성측정방법에관하여상세히설명한다.
[77]
[78] <평가시험항목 >
[79] 1) XRD측정
[80] 입자의평규춤^거리
[81] X-ray희절법을이용하여측정한 2Θ값의그래프를얻어그래프의피크위치를 적분법에의해구하여 Bragg공식에의해 d002(d002 = /2sin0)를계산한다. CuKa선의파장은 0.15406nm로하였다.이때，측정범위는 2.50~ 80°이며，측정 속도는 5 min으로하였다.
[82] (Bragg공식)
[83] 2)비표며적측정
[84] KS A 0094, KS L ISO 18757규격에따라시료를채취하여전처리장치를통해 300oC에서 3시간탈가스처리후 Surface Area, Pore Size Analyzer장치를통해 질소가스기체흡착 BET법에의한압력구간 (P/P0) 0.05~0.3에서시료의 비표면적을측정하였다.
[85] 3) t-plot측정 (Micro Pore volume측정、
[86] 비표면적측정시와동일하게시료를전처리후 Surface Area, Pore Size
Analyzer장치를통해측정한다. Micropore가존재하는것이확인되면 Pore Size Distribution을해석시 t-plot을이용한다.즉， t-plot을이용하여 pore size에따른 형태를알수있다.
[87] Micropore Surface Area = Total surface areaExternal surface area
[88] Mesopore Volume = Total pore volumeMicropore volume
[89] Micropore Volume percent = Micropore volume/Total pore volume * 100
[90] 4)표며기공사이즈분석 (Micro pore size측정 )
[91] 전처리장치를통해 300°C에서 3시간동안탈가스처리후 Pore Size
Analyzer(Bellsorp mini Π)를통해질소가스기체흡착법에의해시료표면의 기공을분석하였다.
[92] 분석은 HK method법에의해 2nm이하크기의직경을갖는기공 (Micropore)의 전체부피분포도로나타내었으며， BJH method법에의해 2~50nm크기의직경을 갖는기공 (Mesopore)의전체부피분포도로나타내었다.
[93] Micropore < 2nm
[94] Mesopore = 2 - 300nm
[95] 5)수분흡착량측정
[96] 제조된탄소를상대습도 70%,온도 25°C의조건에서 24시간방치후 Karl ί fischer수분측정장비를이용하여 200°C에서 5분간유지하여시료에롭착된 수분의양을측정하였다.
[97] 6)측정셈의제조방범및충방저특성평가
[98] 측정셀은코인형반쪽전지로서음극활물질과바인더를 97:3의비율로제조한 전극과상대전극으로리튬금속박을사용하였으며，분리막을사이에두고 유기전해액으로 EC/DEC가 1:1비율로흔합되어있고 1M의 LiPF6가용해된 전해액을함침하여 2016 type코인셀로제조하였다.
[99] 7)춤방전특성평가
[100] 층전은 0.1 C rate로 0.005V까지정전류법으로탄소전극에리륨이온을
삽입시키고 0.005V부터정전류법으로리튬이온삽입을진행시키다가전류가 0.01mA가될때리튬이온삽입을종료하였다.방전은 0.1C rate로정전류법으로 종지전압을 1.5V로하여리튬이온을탄소전극으로부터탈리시켰다.삽입량대비 탈리량의비율이초기효율이며，탈리된양을무게당용량으로변환하여 가역용량을계산하였다.
[101] 8)상온방저출력특성펴가
[102] 상온출력특성평가는 25°C에서리튬이온방전시의출력특성을측정한
것으로서초기 0.1 C로 3사이클층방전진행후 0.2 C로 3사이클층방전을 진행하고이후부터방전 (리튬이온탈리) C rate만단계적으로증가시키면서 0.2 C rate가역용량대비 5 C-rate가역용량의유지율올측정하였다.
[103] 9)저은방전출력특성평가
[104] 저온출력특성평가는 25°C에서리튬이온방전시의출력특성올측정한
것으로서초기 0.1 C로 3사이클층방전진행후 0.2 C로 3사이클층방전을 진행하고이후부터방전 (리튬이온탈리) C rate만단계적으로증가시키면서 0.2 C rate가역용량대비 0에서의 5 C-rate가역용량의유지율을측정하였다.
[105] 10)저읕춤전출력특성평가
[106] 저온충전출력특성평가는 0에서리튬이은층전시의출력특성을측정한
것으로서초기 0.1 C로 3사이클층방전진행후 0.2 C로 3사이클층방전을 진행하고이후에 0oC에서 0.2 C로층전하여상은 0.2 C충전대비층전지수를 측정하였다.
[107]
[108] [실시예 1]
[109] 음극활물짐의제조
[110] 이축연속흔련기에 D50이 18 인구형천연흑연올 20kg/hr,폴리올
조성물에서폴리올 (SSP-104HC,애경유화社)을 1.3kg/hr및아세톤을 3.1kg/hr의 투입속도로동시투입한다음，교반진행중에흔련기의흔련조중간부분에 이소시아네이트 (JG55K,금호미쓰이화학社)를 2.5 kg/hr의투입속도로투입한다. 흔련기의냉각자켓의온도는 -15°C로설정하였으며, (이때교반기내부반죽의 실제온도는약 7°C로측정)건조공정은연속식컨베이어벨트타입 열풍건조기를사용하였으며，건조기실내은도는 80°C로설정하였고, 15분간 건조및경화반웅을진행하여열경화성수지가코팅된구형흑연인
탄소복합체를수득하였다.수득된탄소복합체를질소분위기에서 700°C에서 1차 열처리하고, 1250°C에서 2차열처리하여약 15nm두께의난혹연화성탄소층이 형성된음극활물질을제조하였다.제조된음극활물질의물성을측정하여하기 표 2에나타내었다.난흑연화성탄소의탄화수율을 34%에맞게설정하여 폴리올과이소시아네이트의양을결정하여투입한다.
[111] [실시예 2]
[112] 하기표 1에나타난바와같이 ,플리올 (SSP-104HC,애경유화社)올 1.0kg/hr, 아세톤을 4.0kg/hr및이소시아네이트 (JG55K,금호미쓰이화학社)를 1.9kg/hr의 속도로투입한것을제외하고실시예 1과동일하게실시하여음극활물질을 제조하였다.제조된음극활물질의물성을측정하여하기표 2에나타내었다. 난연화성탄소의탄화수율은실시예 1과동일하게설정하여실시하였다.
[113] [실시예 3]
[114] 하기표 1에나타난바와같이,폴리을 (SSP-104HC,애경유화社)폴리올을
0.8kg/hr,아세톤을 4.6kg/hr및이소시아네이트 (JG55K,금호미쓰이화학社)를 1.6kg/hr의속도로투입한것을제외하고실시예 1과동일하게실시하여음극 활물질을제조하였다.제조된음극활물질의물성을측정하여하기표 2에 나타내었다.
[115] [실시예 4]
[116] 하기표 1에나타난바와같이, D50이 12 인구형천연흑연을사용한것을 제외하고실시예 1과동일하게실시하여음극활물질을제조하였다.제조된 음극활물질의물성올측정하여하기표 2에나타내었다.
[117] [실시예 5]
[118] 하기표 1에나타난바와같이， D50이 10；圆인구형천연흑연을사용한것을 제외하고실시예 1과동일하게실시하여음극활물질을제조하였다.제조된 음극활물질의물성을측정하여하기표 2에나타내었다.
[119] [실시예 6]
[120] 하기표 1에나타난바와같이,혼련공정을공자전믹서를사용한것을
제외하고는실시예 1과동일하게실시하여음극활물질을제조하였다.제조된 음극활물질의물성올측정하여하기표 2에나타내었다.
[121] [실시예 7]
[122] 하기표 1에나타난바와같이，흔련공정을임펠러믹서를사용한것을
제외하고는실시예 1과동일하게실시하여음극활물질을제조하였다.제조된 음극활물질의물성을측정하여하기표 2에나타내었다.
[123] [실시예 8]
[124] 하기표 1에나타난바와같이,건조공정을챔버형연속식열풍건조기를사용한 것과열풍의속도를 3m/sec로조절한것을제외하면실시예 1과동일하게 실시하여음극활물질을제조하였다.제조된음극활물질의물성을측정하여 하기표 2에나타내었다.
[125] [실시예 9]
[126] 하기표 1에나타난바와같이，건조공정을단속식열풍건조로를사용한것을 제외하면실시예 1과동일하게실시하여음극활물질을제조하였다.제조된 음극활물질의물성을측정하여하기표 2에나타내었다.
[127] [비교예 1]
[128] 하가표 1에나타난바와같이,임펠러방식교반기에 D50이 18 인구형
천연혹연올 10kg과탄화수율이 65%이며평균입경이약 2um로미분쇄된석유계 피치를 0.65kg동시투입하여 150rpm으로 30분간흔합하여피치미분말이고르게 분포한흑연피치복합체를제조하였다.제조된복합체는질소분위기에서 700°C에서 1차열처리하고， 1250°C에서 2차열처리하여이흑연화성탄소층이 형성된음극활물질을제조하였다.이연화성탄소의전구체인핏치는탄화수율 64%로설정하여투입하였다.
[129] [비교예 ¾
[130] 하기표 1에나타난바와같이，폴리올 (SSP-104HC,애경유화社)올 2.8 kg/hr및 및이소시아네이트 (JG55K,금호미쓰이화학社)를 5.4 kg/hr의속도로투입한 것과아세톤은사용하지않은것을제외하고실시예 1과동일하게실시하여 음극활물질을제조하였다.제조된음극활물질의물성을측정하여하기표 2에 나타내었다.
[131] [비교예 3]
[132] 하기표 1에나타난바와같이,폴리올 (SSP-104HC,애경유화社)폴리올을
0.3kg/hr,아세톤을 6.2kg/hr및이소시아네이트 (JG55K,금호미쓰이화학社)를 0.5kg/hr의속도로투입한것을제외하고실시예 1과동일하게실시하여음극 활물질을제조하였다.제조된음극활물질의물성을측정하여하기표 2에 나타내었다.
[133] [비교예 4]
[134] 하기표 1에나타난바와같이 ,폴리올 (SSP-104HC,애경유화社)폴리올을
2.3kg hr,아세톤을 4.0kg/hr및이소시아네이트 (JG55K,금호미쓰이화학社)를 0.7kg hr의속도로투입한것을제외하고실시예 1과동일하게실시하여음극 활물질을제조하였다.제조된음극활물질의물성을측정하여하기표 2에 나타내었다.
[135] [비교예 5]
[136] 하기표 1에나타난바와같이，폴리올 (SSP-104HC,애경유화社)폴리을을
0.8kg/hr,아세톤을 3.9kg/hr및이소시아네이트 (JG55K,금호미쓰이화학社)를 2.3kg/hr의속도로투입한것을제외하고실시예 1과동일하게실시하여음극 활물질을제조하였다.제조된음극활물질의물성을측정하여하기표 2에 나타내었다. [137] [비교예 6]
[138] 하기표 1에나타난바와같이，평균입경 18 의처리하지않은구형
천연흑연을그대로사용하였으며,물성을측정하여하기표 2에나타내었다.
[139]
[140] [표 1]
[141]
Figure imgf000015_0001
[142] [표 2]
[143]
표면 분석
수분함량
Micro pore Micro pore
비표면적 (ppm.제조 후 volume size
(m2/g) 24시간 경과)
(cm3/g) (ran)
실시예 1 8.1 0.000465 1.25 108 실시예 2 7.3 0.000437 1.23 121 실시에 3 6.2 0.000398 1.18 131 비교예 1 2.5 0.000023 3.45 128 비교예 2 2.7 0.000544 1.35 101 비교예 3 5.1 0.000084 1.03 140 [144] 도 1(a)는본발명의비교예 6에사용된천연흑연의표면올측정한 주사전자현미경 (SEM)사진을나타낸것이며,도 1(b)는본발명의실시예 1에 따라제조된음극활물질의표면을측정한주사전자현미경 (SEM)사진이다.
[145] 도 1(a)와도 1(b)의외관이거의차이가없는것으로보아본발명의일
실시예에따르면,균일한난혹연화성탄소층을형성할수있음을알수있다.
[146] 도 2는본발명의비교예 6및실시예 1에따른음극활물질의입도분포비교 그래프이다.
[147] 상기도 2를참조하면,비교예 6에따른원료천연흑연대비실시예 1에따라 제조된음극활물질의입도가거의차이가없어난흑연화성탄소층이얇고 균일하게형성되었음을알수있다.
[148] 도 3내지도 5는각각본발명의실시예 2，비교예 1및비교예 2에따라제조된 음극활물질의표면을측정한투과전자현미경 (TEM)사진이다.
[149] 상기도 3을참조하면,본발명의일실시예에따라제조된음극활물질의
난흑연화성코팅층의두께는 3내지 30nm사이로균일하게코팅되어있음을 확인할수있다.그러나，도 4를참조하면피치를코팅한비교예 1의경우，코팅이 되지않은곳이있으며두께편차가 0내지 8 nm로균일하지않은것을알수 있었다.
[150] 상기표 2은본발명의실시예및비교예에따른음극활물질의비표면적과 기공분석결과를나타낸표이다.표 2을참조하면본원발명의일실시예에따른 난흑연화성코팅층이형성된음극활물질의비표면적이비교예 6의원료혹연에 비하여현저히증가되는것을알수있다.또한,표면마이크로기공의 평균크기가 1내지 2mn로균일하게분포하는것을알수있다.
[151] 일반적으로리튬이차전지용음극활물질에서비표면적이크고기공이
발달할수록수분함유량이높아지는우려와，전극슬러리제조에있어용매가 많이요구되어고형분농도가낮아지는단점이있으나,본원발명에따른음극 활물질은상기표 2의결과를참조하여볼때비표면적은크지만표면마이크로 기공의사이즈가약 lnm정도로매우작은것으로인해전술한문제가해결된 것을알수있다.상기표 2의실시예및비교예에서제초된음극활물질의제조 후 1시간후의수분함량을참고하면난흑연화성탄소가코팅된본원발명의 음극활물질은피치가코팅된비교예 1에비해같거나더낮은수준의수분 함량을보임올알수있다.
[152]
[153] r심험예 11이차저지의제조
[154] (a)전극제작
[155] 상기제조된음극활물질 97중량부에 SBR(Stylene Butadiene Rubber) 1.5
중량부， CMC(Carboxyl Methyl Cellulose) 1.5중량부를첨가하여증류수를 첨가하며슬러지형태로균일하게교반하여구리호일상에균일하게 코팅하였다.코팅은닥터블레이드를사용하여 110；圆로균일하게코팅하였고 60°C오본에서 30분간건조하여 0.6Mpa의압력으로프레스를시행하였다.호일 상의전극을넓이 1cm2의원형으로펀칭하여 120oC진공오븐에서 12시간 건조하였다.
[156] (b)시험전지의제작
[157] 상기실시예및비교예에서제조된음극활물질은수계전해질이차전지의
음극에사용하였으며,음극활물질의층전 (리튬삽입)용량및방전 (리튬탈리) 용량이대극의성능에영향을받지않고단독적으로정밀하게평가하기위하여 리튬금속을대극으로사용하여리튬이차전지를구성하고,특성을평가하였다.
[158] 리튬이차전지는 2016사이즈 (직경 20mm,두께 16mm)의코인형전지로
아르곤분위기하의글로브박스내에서조립되었으며， 1mm두께의금속리튬을 코인형전지캔의바닥에압착하였고그위에폴리프로필렌재질의분리막을 형성하고，음극을리튬과마주보게하였다.이때，사용된전해질은 EC(EthyIene Carbonate)와 DMC(Dimethyl Carbonate), EMC(Ethyl Methyl Carbonate)를부피비 1:1:1로흔합하여제조된용매에 1.2M의 LiPF6염을첨가하여제조된것으로 코인형전지에투입하여캔커버를닿고압착하여리튬이차전지를조립하였다.
[159] (c)전지용량측정
[160] 상기조립된리튬 2차전지에대한특성분석은 TOYO SYSTEM社에서제조된 ^^ ^^^아충방전시험장치를이용하여정전류-정전압법 (CCCV)에의해 25 C에서층방전을시행하였다.여기서 '층전 '은음극에리튬이삽입되는 반응으로코인형전지의전압이낮아지는반웅이고， '방전 '은리튬이음극에서 탈리되어대극쪽으로이동하는반웅으로,코인형전지의전압이높아지는 반웅이다.또한여기서정전류-정전압조건은코인형전지의전압이 0.005V가될 때까지일정한전류밀도 (0.1C기준)로층전을행하고,그후에전압을유지한채 전류값이 0.05mA가될때까지일정하게감소시켜층전을진행한다.이때 공급한전기량을전극의음극활물질의증량으로나눈값을음극활물질의 단위중량당층전용량 (mAh/g)이라하였다.층전종료후， 10분간전지의작동을 멈추고방전을시행하였다.방전은코인형전지의전압이 1.5V가될때까지 일정한전류로시행하였고，이때방전한전기량을전극의음극활물질의 증량으로나눈값을음극활물질의단위중량당방전용량 (mAh/g)이라하였다. 가역용량은방전용량으로정의하였으며비가역용량은층전용량에서
방전용량을뺀용량으로계산하였고효을은층전용량대비방전용량을 퍼센트 (^로계산하였다.기본적인코인형전지의특성값은동일시료로제작한 동일전지 3개이상의특성값을평균하여나타내었다.
[161] (d)고율충방전특성측정
[162] 상기조립된리튬 2차전지에대한고율충방전특성분석은 (c)와동일하게 정전류-정전압법 (CCCV)에의해 250C에서시행하였다.고율층방전특성은 층방전시의전류밀도를변화시켜,공급또는방전되는일정한전류밀도를 사이클별로증가시켜그전류밀도에서층방전되어측정되는용량 (mAh/g)으로 나타내었다.
[163]
[164] 상기실시예및비교예에서제조된음극활물질의초기층방전용량과효율을 측정하여하기의표 3에나타내었다.
[165] [표 3]
[166]
Figure imgf000018_0001
[167] 상기표 3에나타난바와같이，본발명의일실시예에따른난혹연화성
코팅층이형성된탄소복합체를음극활물질로사용할경우，그렇지않은비교예 1또는비교예 6에비하여비가역용량이감소하고층방전효율이증가하여초기 효율이증가되는것을알수있다.
[168] 실시예 4및 5에따른음극활물질은입경이다른구형천연흑연을사용했을 경우에도실시예 1과마찬가지로우수한초기효율을보이는것을알수있다.
[169] 그러나비교예 2와같이열경화성수지코팅량이 34.48%로많거나,비교예 3과 같이 3.44%로적을때는초기효율개선효과는있지만그효과가상대적으로 크지않음을알수있다
[170] 사이클에따른용량유지율에서는비교예 1과같이피치를코팅하거나,
실시예와같이하드카본을코팅한경우모두비교예 6에서와같이,코팅층을 형성하지않은원료혹연에비해용량유지율이향상됨을알수있다.
[171] 동일함량의탄소함량에서는피치를코팅한비교예 1에비해실시예 2에따른 음극활물질을사용한리튬이차전지의용량유지율이우수한것으로나타났다.
[172] C-rate에따른상온용량유지율도사이클에따른용량유지율과유사한 경향으로나타남을알수있다.대체로열경화성수지코팅량이증가할수록 우수한특성을보이지만,열경화성수지코팅량 34.48%인비교예 2의경우는 열경화성코팅량 17.58%인실시예 1에비해열위한상온 C-rate용량유지율을 보인다.
[173] 특히,실시예 5와같이，입경이작은흑연을사용한경우저온 c-rate
용량유지율에서최대의성능을발휘할수있는것으로보인다.상기표 3의 실시예 4및 5의결과를참조하면구형천연혹연입경각각 l zm및 10 를 사용한경우가평균입경 18의구형천연흑연을사용한실시예 2의경우에비해 저온 c-rate용량유지율이우수한것을알수있다.
[174] 또한,상기표 1에서이소시아네이트비율은폴리을 100증량부를기준으로 했을때，이소시아네이트계화합물의중량에대한첨가비율 (%)를나타낸 것이다.상기표 3에나타난바와같이，이소시아네이트비율이 100내지 250중량부，즉 100내지 250%일때，초기효율개선효과가두드러지는것을알 수있다.
[175] 이소시아네이트비율이비교예 4와같이너무작거나,비교예 5와같이너무클 경우,초기효율개선효과가감소되며，사이클용량유지율의개선효과도 미미함을알수있었다.
[176] 이상에서설명한본발명은전술한실시예및첨부된도면에의해한정되는 것은아니고,본발명의기술적사상을벗어나지않는범위내에서여러가지 치환,변형및변경이가능함은본발명이속하는기술분야에서통상의지식올 가진자에게있어서명백할것이다.

Claims

청구범위
[청구항 1] 폴리올조성물및이소시아네이트계화합물을포함하는열경화성 수지조성물이코팅된탄소계입상소재를비활성기체분위기 하에서열처리하여탄소화시킨탄소복합체를포함하는리튬 이차전지용음극활물질.
[청구항 2] 제 1항에있어서,
상기열경화성수지조성물은상기입상소재의표면에서경화되어 폴리우레탄수지를형성하며，
상기폴리우레탄수지는폴리이소시아누레이트를함유하는것을 특징으로하는리튬이차전지용음극활물질.
[청구항 3] 제 2항에있어서,
상기탄소복합체는상기입상소재표면에평균두께 3내지 30nm의 난흑연화성탄소층을형성시키는것을특징으로하는리튬 이차전지용음극활물질.
[청구항 4] 제 2항에있어서，
상기열경화성수지조성물은전체음극활물질에대하여， 5내지 25증량 %를포함하는리튬이차전지용음극활물질.
[청구항 5] 제 1항에있어서,
상기열경화성수지조성물은상기폴리올조성물 100증량부에 대하여，이소시아네이트계화합물을 100내지 250중량부 포함하는리튬이차전지용음극활물질.
[청구항 6] 제 5항에있어서，
상기폴리을조성물은폴리을，유기용매，첨가제및촉매를 포함하며，
상기폴리올조성물의고형분함량이 10내지 70중량 <¾인것을 특징으로하는리튬이차전지용음극활물질.
[청구항 7] 제 6항에있어서，
상기폴리올은폴리에테르계폴리올,폴리에스테르계폴리올, 폴리테트라메틸렌에테르글리콜폴리올，피에이치디
폴리을 (Polyharnstoff Dispersion(PHD) polyol),아민 (Amine)변성 폴리올，만니히 (Manmich)폴리을및이들의혼합물중에서 선택되는어느하나또는둘이상인리튬이차전지용음극활물질.
[청구항 8] 제 5항에있어서,
상기이소시아네이트계화합물은핵사메틸렌디이소시아네이트, 이소포론디이소시아네이트， 4，4'-디시클로핵실메탄
디이소시아네이트，폴리에틸렌폴리페닐이소시아네이트，를루엔 디이소시아네이트， 2,2-디페닐메탄디이소시아네이트， 2,4-디페닐메탄디이소시아네이트, 4，4'-디페닐메탄
디이소시아네이트，폴리머릭디페닐메탄디이소시아네이트, 오르토톨루이딘디이소시아네이트，나프탈렌디이소시아네이트, 크실렌디이소시아네이트,라이신디이소시아네이트및 트리페닐메탄트리이소시아네이트중에서선택되는어느하나 또는둘이상인리튬이차전지용음극활물질.
제 1항내지제 8항중에서선택되는어느한항에있어서, 비표면적이 5내지 10 m2/g이고,표면마이크로기공의평균크기가
1내지 2mn인리튬이차전지용음극활물질.
리튬이차전지용음극활물질의제조방법에있어서,
a)입상소재와폴리올조성물과이소시아네이트계화합물을 포함하는열경화성수지조성물을흔합하는단계;
b)상기열경화성수지조성물과입상소재의흔합물을건조및 경화시켜열경화성수지가코팅된입상소재를제조하는단계; c)상기열경화성수지가코팅된입상소재를비활성기체분위기 하에서열처리하여탄소화시킨탄소복합체를제조하는단계;및 d)상기탄소복합체를해쇄하는단계 ;를포함하며，
상기열경화성수지조성물은전체음극활물질에대하여， 5내지 25중량 %를포함하여,상기입상소재표면에평균두께 3내지 30nm의난흑연화성탄소층을형성하는리튬이차전지용음극 활물질의제조방법.
제 10항에있어서,
상기 a)단계의흔합은일축흔련기,이축흔련기또는배치식 흔련기에서 10°C이하에서수행하며,
상기 b)단계의건조및경화는챔버,열처리부및배기구가구비된 장치에서 60내지 150oC의열풍가열로수행되는것을특징으로 하는리튬이차전지용음극활물질의제조방법.
제 10항에있어서,
상기 c)단계의열처리는 1차열처리및 2차열처리중에서적어도 하나를포함하고，
상기 1차열처리는 500내지 1,000°C온도에서，상기 2차열처리는 900내지 1,500°C온도에서진행하는리튬이차전지용음극 활물질의제조방법 .
제 10항에있어서，
상기 d)해쇄하는단계는모터에의해회전하는원형로터에의해 회전하고，회전로터에적어도 2개이상의분쇄바가장착되어 있으며，분쇄바의단면형상은원형내지는다각형인형태의 분쇄기로처리하는리튬이차전지용음극활물질의제조방법. [청구항 14] 제 1항내지제 8항중에서선택되는어느한항의리튬이차전지용 음극활물질을포함하는리튬이차전지.
[청구항 15] 제 I4항에있어서，
상기리튬이차전지의비가역용량은 10내지 31mAh/g이며, 50회 사이클용량유지율이 90%이상인것을특징으로하는리튬 이차전지.
PCT/KR2015/000728 2014-01-24 2015-01-23 리튬이차전지용 음극 활물질 및그 제조방법, 이를 이용한 리튬 이차전지 WO2015111954A1 (ko)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100373582B1 (ko) * 1997-04-08 2003-04-11 주식회사 엘지화학 이소시아네이트 화합물을 포함하는 리튬이온 전지또는 리튬이온폴리머전지용 음극전극 코팅액, 이를 이용한 음극전극 및 이의 제조방법
KR20050084413A (ko) * 2002-12-19 2005-08-26 제이에프이 케미칼 가부시키가이샤 복합 흑연 입자 및 그의 제조방법, 및 이것을 이용한 리튬이온 2차 전지의 음극재 및 리튬 이온 2차 전지
JP2005259641A (ja) * 2004-03-15 2005-09-22 Mitsubishi Heavy Ind Ltd リチウム二次電池用の電解液、電極、リチウム二次電池およびそれらの製造方法
JP2010118243A (ja) * 2008-11-12 2010-05-27 Kansai Coke & Chem Co Ltd リチウムイオン二次電池用負極材料とその製造方法、及び、該負極材料を用いたリチウムイオン二次電池
KR20120078645A (ko) * 2010-12-31 2012-07-10 애경유화 주식회사 리튬이차전지용 음극 활물질 및 그 제조방법, 이를 이용한 리튬이차전지

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4215633B2 (ja) * 2002-12-19 2009-01-28 Ｊｆｅケミカル株式会社 複合黒鉛粒子の製造方法
JP4937737B2 (ja) * 2004-03-30 2012-05-23 株式会社クレハ 非水電解質二次電池用負極材料、その製造方法、負極および電池
JP2011048987A (ja) * 2009-08-26 2011-03-10 Sony Corp 負極、非水電解質二次電池及びその製造方法
WO2012091515A2 (ko) * 2010-12-31 2012-07-05 애경유화 주식회사 리튬이차전지용 음극 활물질 및 그 제조방법, 이를 이용한 리튬이차전지
KR20140140323A (ko) 2013-05-29 2014-12-09 (주)포스코켐텍 리튬 이차 전지용 음극 활물질, 이의 제조 방법 및 이를 포함하는 리튬 이차전지

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100373582B1 (ko) * 1997-04-08 2003-04-11 주식회사 엘지화학 이소시아네이트 화합물을 포함하는 리튬이온 전지또는 리튬이온폴리머전지용 음극전극 코팅액, 이를 이용한 음극전극 및 이의 제조방법
KR20050084413A (ko) * 2002-12-19 2005-08-26 제이에프이 케미칼 가부시키가이샤 복합 흑연 입자 및 그의 제조방법, 및 이것을 이용한 리튬이온 2차 전지의 음극재 및 리튬 이온 2차 전지
JP2005259641A (ja) * 2004-03-15 2005-09-22 Mitsubishi Heavy Ind Ltd リチウム二次電池用の電解液、電極、リチウム二次電池およびそれらの製造方法
JP2010118243A (ja) * 2008-11-12 2010-05-27 Kansai Coke & Chem Co Ltd リチウムイオン二次電池用負極材料とその製造方法、及び、該負極材料を用いたリチウムイオン二次電池
KR20120078645A (ko) * 2010-12-31 2012-07-10 애경유화 주식회사 리튬이차전지용 음극 활물질 및 그 제조방법, 이를 이용한 리튬이차전지

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