WO2022098135A1 - Positive electrode active material for lithium secondary battery, and lithium secondary battery comprising same - Google Patents

Positive electrode active material for lithium secondary battery, and lithium secondary battery comprising same Download PDF

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WO2022098135A1
WO2022098135A1 PCT/KR2021/015952 KR2021015952W WO2022098135A1 WO 2022098135 A1 WO2022098135 A1 WO 2022098135A1 KR 2021015952 W KR2021015952 W KR 2021015952W WO 2022098135 A1 WO2022098135 A1 WO 2022098135A1
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Prior art keywords
active material
particles
positive electrode
positive
primary
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PCT/KR2021/015952
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French (fr)
Korean (ko)
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한기범
노은솔
도중엽
박강준
곽민
박상민
이대진
이상욱
정왕모
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주식회사 엘지에너지솔루션
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Publication of WO2022098135A1 publication Critical patent/WO2022098135A1/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
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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 cathode active material for a lithium secondary battery comprising primary large particles and a method for manufacturing the same.
  • lithium secondary battery has been in the spotlight as a driving power source for a portable device because it is lightweight and has a high energy density. Accordingly, research and development efforts for improving the performance of lithium secondary batteries are being actively conducted.
  • an organic electrolyte or polymer electrolyte is charged between a positive electrode and a negative electrode made of an active material capable of intercalation and deintercalation of lithium ions, and lithium ions are inserted/deintercalated from the positive electrode and the negative electrode.
  • the conversion of electrical energy and chemical energy occurs by a reduction reaction with
  • lithium cobalt oxide (LiCoO 2 ) As a positive active material of a lithium secondary battery, lithium cobalt oxide (LiCoO 2 ), lithium nickel oxide (LiNiO 2 ), lithium manganese oxide (LiMnO 2 or LiMn 2 O 4 , etc.), lithium iron phosphate compound (LiFePO 4 ), etc. are used. .
  • lithium cobalt oxide (LiCoO 2 ) has the advantage of high operating voltage and excellent capacity characteristics, and is widely used, and is applied as a high-voltage positive electrode active material.
  • there is a limit to mass use as a power source in fields such as electric vehicles due to an increase in the price of cobalt (Co) and unstable supply, and the need to develop a positive electrode active material that can replace it has emerged.
  • 'NCM-based lithium composite transition metal oxide' nickel-cobalt-manganese-based lithium composite transition metal oxide in which a part of cobalt (Co) is substituted with nickel (Ni) and manganese (Mn) has been developed.
  • the positive electrode active material may be secondary particles formed by gathering primary particles.
  • the positive electrode active material may be secondary particles formed by gathering primary particles.
  • the breaking of primary particles and/or secondary particles in the rolling step which is one of the electrode manufacturing processes, the movement path of electrons in the electrode is lost and the surface area where side reactions with the electrolyte can occur increases. As a result, there is a problem in that the life characteristics are inferior.
  • An object of the present invention is to solve the above problems, and to provide a positive electrode active material capable of minimizing particle breakage during rolling by controlling particle size and shape.
  • One aspect of the present invention provides a cathode active material according to the following embodiments.
  • the first positive active material includes at least one secondary large particle including an aggregate of primary micro particles,
  • the second positive active material includes at least one secondary small particle including an aggregate of primary macro particles,
  • the average particle diameter (D50) of the primary large particles is 1 ⁇ m or more
  • the ratio of the average particle diameter (D50) of the first positive electrode active material / the average particle diameter (D50) of the second positive electrode active material is 2 or more
  • the weight ratio of the first positive active material and the second positive active material is 50: 50 to 70: 30, it relates to a lithium secondary battery positive electrode active material, characterized in that.
  • the average diameter (D50) of the primary large particles is 2 ⁇ m or more
  • the ratio of the average particle diameter (D50) of the primary large particles to the average crystal size of the primary large particles is 2 or more.
  • a third embodiment according to the first or second embodiment,
  • the first positive electrode active material has an average particle diameter (D50) of 10 ⁇ m to 20 ⁇ m.
  • a fourth embodiment according to any one of the first to third embodiments,
  • the second positive electrode active material has an average particle diameter (D50) of 3 ⁇ m to 6 ⁇ m.
  • a fifth embodiment according to any one of the first to fourth embodiments,
  • the average particle diameter (D50) of the primary fine particles of the first positive electrode active material relates to a positive electrode active material for a lithium secondary battery, characterized in that 0.1 ⁇ m to 0.5 ⁇ m.
  • the second positive electrode active material relates to a positive electrode active material for a lithium secondary battery, characterized in that the primary large particles fall off when the secondary small particles are rolled, and the primary large particles themselves are not broken.
  • the rolling relates to a positive electrode active material for a lithium secondary battery, characterized in that the porosity of the positive electrode including the positive electrode active material is 15 to 30%.
  • the average crystal size of the primary large particles relates to a cathode active material for a lithium secondary battery, characterized in that 150 nm or more.
  • a ninth embodiment according to any one of the first to eighth embodiments,
  • the ratio of the average particle diameter (D50) of the secondary small particles to the average particle diameter (D50) of the primary large particles is 2 to 4 times.
  • the first and second positive electrode active materials relate to a positive electrode active material for a lithium secondary battery, characterized in that it includes a nickel-based lithium transition metal oxide.
  • the nickel-based lithium transition metal oxide is, Li (1+a) Ni (1-(a+x+y+w)) Co x M1 y M2 w O 2 (here, 0 ⁇ a ⁇ 0.5, 0 ⁇ x ⁇ 0.35, 0 ⁇ y ⁇ 0.35, 0 ⁇ w ⁇ 0.1, 0 ⁇ a+x+y+w ⁇ 0.7, M1 is at least one selected from the group consisting of Mn and Al, M2 is Ba, Ca, Zr, Ti, Mg, Ta, at least one selected from the group consisting of Nb and Mo) relates to a cathode active material for a lithium secondary battery, characterized in that it contains.
  • the positive active material relates to a positive electrode active material for a lithium secondary battery, characterized in that the ratio of particles smaller than 1 ⁇ m in PSD distribution is less than 10% under the condition that the porosity of the positive electrode including the positive active material is 15 to 30%.
  • the positive electrode active material When the positive electrode active material is pressurized so that the porosity of the positive electrode including the positive active material is 15 to 30%, the peak intensity decrease rate of the secondary large particles before and after the pressurization is less than 2%, characterized in that It relates to a positive electrode active material for a lithium secondary battery.
  • One aspect of the present invention provides a positive electrode for a lithium secondary battery according to the following embodiments.
  • a fourteenth embodiment provides a positive electrode for a lithium secondary battery comprising the positive electrode active material according to any one of the above-described embodiments.
  • One aspect of the present invention provides a lithium secondary battery according to the following embodiments.
  • a fifteenth embodiment provides a lithium secondary battery including the positive electrode active material according to any one of the above embodiments.
  • the amount of particle breakage or fine powder generation during rolling is significantly suppressed, thereby greatly improving the lifespan characteristics. can be improved
  • the amount of particle breakage or fine powder generation during rolling is significantly suppressed, thereby greatly improving the lifespan characteristics.
  • Example 1 is a SEM image of a cross-section of an electrode to which a positive active material according to Comparative Example 1 is applied.
  • Example 2 is a SEM image of a cross-section of an electrode to which a positive active material according to Comparative Example 2 is applied.
  • Example 3 is a SEM image of a cross-section of an electrode to which a positive active material according to Example 1 of the present invention is applied.
  • the crystal size of the crystal grains may be quantitatively analyzed using X-ray diffraction analysis (XRD) by Cu K ⁇ X-rays.
  • XRD X-ray diffraction analysis
  • the average crystal size of the crystal grains can be quantitatively analyzed by putting the prepared particles in a holder and analyzing the diffraction grating that irradiates X-rays to the particles.
  • D50 may be defined as a particle size based on 50% of a particle size distribution, and may be measured using a laser diffraction method.
  • the particles of the positive active material are dispersed in a dispersion medium, and then introduced into a commercially available laser diffraction particle size measuring device (eg, Microtrac MT 3000) to about 28 kHz
  • a commercially available laser diffraction particle size measuring device eg, Microtrac MT 3000
  • the term 'primary particles' refers to particles having no apparent grain boundaries when observed in a field of view of 5000 times to 20000 times using a scanning electron microscope.
  • the primary particles may be classified into primary micro particles and primary macro particles according to an average particle diameter (D50).
  • 'secondary particles' are particles formed by agglomeration of the primary particles.
  • secondary particles may be classified into secondary large particles and secondary small particles according to an average particle diameter (D50).
  • the secondary large particle may be referred to as a secondary large particle.
  • the secondary particle large particle is a particle formed by aggregation of tens to hundreds of primary micro particles.
  • Secondary particles Small particles exist as a concept in contrast to large particles.
  • the secondary particle small particle is a particle formed by aggregation of several tens to hundreds of primary micro particles.
  • the average particle diameter (D50) of the large secondary particles is larger than the average particle diameter (D50) of the small secondary particles.
  • the secondary small particle referred to in the present invention is different from the above-described large secondary particle and/or secondary particle small particle. That is, the secondary small particles in one aspect of the present invention are preferably particles formed by aggregation of about 10 primary micro particles.
  • Secondary particles formed by agglomeration of primary fine particles Large secondary particles/ When comparing small secondary particles and secondary small particles formed by agglomeration of primary large particles, secondary particles formed by aggregation of primary large particles are more have a smooth surface.
  • 'single particle' is a particle that exists independently of the secondary particles and does not have a grain boundary in appearance, for example, a particle having a particle diameter of 0.5 ⁇ m or more.
  • 'particle' when 'particle' is described, it may mean that any one or all of single particles, secondary particles, and primary particles are included.
  • the cathode active material is used as a cathode active material by mixing two types of particles having different particle size distributions in order to improve energy density per volume.
  • the bimodal effect causes a higher density than the value calculated arithmetically from the density values of large and small particles under the same pressure condition. do.
  • a positive electrode active material including a secondary particle shape different from the conventional one.
  • the first positive active material includes at least one secondary large particle including an aggregate of primary micro particles,
  • the second positive active material includes at least one secondary small particle including an aggregate of primary macro particles,
  • the average particle diameter (D50) of the primary large particles is 1 ⁇ m or more
  • the ratio of the average particle diameter (D50) of the first positive electrode active material / the average particle diameter (D50) of the second positive electrode active material is 2 or more
  • the weight ratio of the first positive active material to the second positive active material is a positive active material, characterized in that 50:50 to 70:30.
  • the positive active material may provide a nickel-based positive active material having an increased charge/discharge capacity retention rate by having the above characteristics.
  • the primary large particles include secondary particles agglomerated.
  • the existing secondary particles tens to hundreds of primary fine particles are aggregated to form secondary particles.
  • the primary large particles having an average particle diameter (D50) of 1 ⁇ m or more are preferably aggregated within 1 to 10 to constitute “secondary small particles”.
  • the present inventors have discovered that, in the case of mixing the existing large secondary particles and small secondary particles, cracking of the secondary particles occurs during the rolling process and there is a problem in that the electrochemical properties are inferior.
  • the existing large secondary particles and small secondary particles are secondary particles formed by aggregation of tens to hundreds of primary fine particles, but with a large average diameter (D50), “large secondary particles” , the case where the average diameter (D50) is small is referred to as “small secondary particles”.
  • the present invention by mixing the “secondary small particles in which the primary large particles are aggregated” with the existing “large secondary particles” in an appropriate ratio, cracking in the rolling process can be suppressed.
  • the secondary small particles according to the present invention are mixed with the existing secondary large particles, the press density of the secondary small particles is relatively high, so that the secondary large particles at the same rolling density for the entire mixed positive electrode active material. This appears to be due to the reduced stress on the particles.
  • the surface of the secondary small particle according to the present invention is smoother than the conventional secondary particle small particle, and thus it seems to effectively exhibit a bimodal effect when mixed with the secondary large particle.
  • 'primary large particles means those having an average diameter (D50) of 1 ⁇ m or more.
  • the average particle diameter of the primary large particles may be 1 ⁇ m or more, 1.5 ⁇ m or more, 2 ⁇ m or more, 2.5 ⁇ m or more, 3 ⁇ m or more, or 3.5 ⁇ m or more, and 5 ⁇ m or less; It may be 4.5 ⁇ m or less, or 4 ⁇ m or less.
  • the average particle diameter of the primary large particles is less than 1 ⁇ m, the agglomerated secondary particles correspond to conventional secondary small particles, and thus there may be a problem in that particles are broken during rolling.
  • 'primary large particles means a ratio of average particle diameter (D50)/average crystal size of 3 or more. That is, the primary large particles have an average particle diameter and an average crystal size of the primary particles grown at the same time as compared to the primary micro particles constituting the conventional secondary particles.
  • the primary large particles refer to particles having a larger average crystal size as well as an average particle diameter as compared to a positive electrode active material in the form of a conventional secondary particle, and having no apparent grain boundaries.
  • the average crystal size of the primary large particles may be quantitatively analyzed using X-ray diffraction analysis (XRD) by Cu K ⁇ X-rays.
  • XRD X-ray diffraction analysis
  • the average crystal size of the primary large particles can be quantitatively analyzed by putting the prepared particles in a holder and analyzing the diffraction grating that irradiates the particles with X-rays. For example, it can be analyzed by the method described above.
  • the ratio of the average particle size (D50) / average crystal size (crystal size) may be 2 or more, 2.5 or more, 3 or more, and 50 or less, 40 or less, 35 or less.
  • the average crystal size of the primary large particles may be 150 nm or more, 170 nm or more, 200 nm or more, and 300 nm or less, 270 nm or less, or 250 nm or less.
  • secondary small particles refers to an aggregated form of the above-described primary large particles.
  • the secondary small particles are different from the conventional method for obtaining single particles in the following points.
  • the existing single particles single particles were formed by increasing only the primary firing temperature by using the existing precursor for secondary particles as it is.
  • the secondary small particles according to an aspect of the present invention use a separate precursor having a high porosity. Accordingly, the primary large particles having a large particle size may be grown without raising the firing temperature, while the average diameter of the secondary small particles may be relatively small compared to the conventional ones.
  • the secondary small particles according to an aspect of the present invention have the same or similar average particle diameter (D50) as the existing secondary particles and have a large average diameter (D50) of the primary particles.
  • D50 average particle diameter
  • the conventional positive electrode active material in which primary particles with small average particle diameters gather to form secondary particles, it provides a secondary particle form in which primary large particles with increased primary particle size are aggregated. do.
  • the secondary small particles may be agglomerated 1 to 10 or less of the primary large particles. More specifically, the secondary small particles may be one or more, two or more, three or more, or four or more aggregates of the primary large particles, and within the numerical range, the primary large particles are 10 It may be an aggregate of no more than 9 pieces, no more than 8 pieces, or no more than 7 pieces.
  • the secondary small particles have a large average diameter (D50) of the primary large particles while having the same or similar average particle diameter (D50) as before.
  • D50 average diameter of the primary large particles while having the same or similar average particle diameter (D50) as before.
  • the secondary particle form in which primary large particles of increased primary particle size are aggregated to provide.
  • the secondary small particles according to an aspect of the present invention have an average diameter (D50) of 3 ⁇ m to 6 ⁇ m. More specifically, it is 3 ⁇ m or more, 3.5 ⁇ m or more, 4 ⁇ m or more, or 4.5 ⁇ m or more, and is 6 ⁇ m or less, 5.5 ⁇ m or less, or 5 ⁇ m or less.
  • D50 average diameter
  • the size of the particles and the average crystal size within the particles increase as the firing temperature increases.
  • the secondary small particles according to an aspect of the present invention by using a porous precursor, primary large particles having a large particle size can be grown without raising the sintering temperature higher than in the prior art, whereas the secondary small particles can grow relatively less than before.
  • the secondary small particles according to one aspect of the present invention have the same or similar average diameter (D50) to the conventional secondary particles, and have larger average diameter and average crystal size than the conventional primary fine particles.
  • the ratio of the average particle diameter (D50) of the secondary small particles to the average particle diameter (D50) of the primary large particles may be 2 to 4 times.
  • the second positive electrode active material of small particles means including the above-described secondary small particles.
  • the second positive active material may be one in which the primary large particles fall off when the secondary small particles are rolled, and the primary large particles themselves are not broken.
  • the rolling condition may be a condition in which the positive electrode active material is manufactured as an electrode and rolled to a level of 15 to 30% porosity.
  • the rolling condition may be to apply a pressure of 9 tons or more. More specifically, it may be to press 9 ton.
  • the cathode active material when the cathode active material is manufactured as an electrode and rolled to a level of 15 to 30% porosity, less than 10% of fine particles of 1 ⁇ m or less are present.
  • the cathode active material according to an aspect of the present invention is produced as an electrode and the maximum peak intensity reduction rate of the secondary large particles is less than 2% when rolled to a porosity level of 15 to 30%.
  • Secondary large particles in which primary fine particles are aggregated and large-particle first positive electrode active material comprising the secondary large particles
  • it further includes a secondary large particle in addition to the secondary small particle described above.
  • the secondary large particles are in the form of agglomerated primary fine particles.
  • the primary fine particles may be in the form of agglomerated tens to hundreds.
  • the "secondary large particle” is the same concept as the above-mentioned "secondary large particle”.
  • the average diameter (D50) of the secondary large particles is 10 ⁇ m to 20 ⁇ m.
  • the average diameter (D50) of the secondary large particles is less than 10 ⁇ m, the particle breakage of the secondary large particles may be increased. More specifically, it is 10 ⁇ m or more, 12 ⁇ m or more, or 14 ⁇ m or more, and is 20 ⁇ m or less, 18 ⁇ m or less, or 16 ⁇ m or less.
  • the average particle diameter (D50) of the primary fine particles is 0.1 ⁇ m to 0.5 ⁇ m. More specifically, it may be 0.1 ⁇ m or more, 0.2 ⁇ m or more, or 0.3 ⁇ m or more, and may be 0.5 ⁇ m or less, or 0.4 ⁇ m or less.
  • the ratio of the average particle diameter (D50) of the first positive active material / the average particle diameter (D50) of the second positive active material is 2 or more, and the first positive active material and the first positive active material 2
  • the weight ratio of the positive active material is 50:50 to 70:30.
  • a weight ratio of the first positive active material to the second positive active material may be 50:50 to 70:30, for example, 55:45 or 60:40, or 65:35.
  • the amount of fine powder formed during rolling is relatively larger than that of the positive active material of the present invention.
  • the amount of unsold may be relatively reduced compared to when the secondary large particles are used alone, but still particles Cracking occurs and capacity retention is low.
  • the lifespan characteristics were significantly improved compared to a composition in which the existing large secondary particles and small secondary particles were mixed, or a composition in which the secondary small particles were used alone.
  • the average particle diameter (D50) of the first positive active material / the average particle diameter of the second positive active material should not be less than 2.
  • the ratio of the average particle diameter (D50) of the first positive active material to the average particle diameter (D50) of the second positive active material may be 2 or more, 3 or more, or 3.5 or more.
  • the secondary large particles and/or secondary small particles include nickel-based lithium transition metal oxide.
  • the nickel-based lithium transition metal oxide is, Li (1+a) Ni (1-(a+x+y+w)) Co x M1 y M2 w O 2 (here, 0 ⁇ a ⁇ 0.5, 0 ⁇ x ⁇ 0.35, 0 ⁇ y ⁇ 0.35, 0 ⁇ w ⁇ 0.1, 0 ⁇ a+x+y+w ⁇ 0.7, M1 is at least one selected from the group consisting of Mn and Al, M2 is Ba, Ca , Zr, Ti, Mg, Ta, at least one selected from the group consisting of Nb and Mo) may include.
  • a, x, y, and w represent the molar ratio of each element in the nickel-based lithium transition metal oxide.
  • the doped metals M1 and M2 in the crystal lattice of the secondary particles may be located only on a part of the surface of the particle according to the position preference of the element M1 and/or the element M2, and the concentration decreases from the particle surface to the particle center It may be positioned with a gradient, or it may be uniformly present throughout the particle.
  • the long life characteristics of the active material may be further improved by stabilizing the surface structure.
  • the positive active material according to an aspect of the present invention may be manufactured by the following method. However, the present invention is not limited thereto.
  • it may be formed by preparing the first positive active material and the second positive active material, respectively, and then mixing.
  • the first positive active material and the second positive active material may be manufactured by the following method.
  • the method comprising: mixing a cathode active material precursor including nickel (Ni), cobalt (Co) and manganese (Mn) and a lithium raw material and performing primary firing; and mixing the lithium raw material after the primary firing and performing secondary firing.
  • secondary particles including primary particles may be manufactured.
  • a method of manufacturing the positive active material will be further described step by step.
  • a cathode active material precursor including nickel (Ni), cobalt (Co), and manganese (Mn) is prepared.
  • the precursor for preparing the first positive electrode active material of large particles may be prepared by purchasing a commercially available positive electrode active material precursor or according to a method for preparing a positive electrode active material precursor well known in the art.
  • the precursor may be prepared by adding an ammonium cation-containing complexing agent and a basic compound to a transition metal solution including a nickel-containing raw material, a cobalt-containing raw material, and a manganese-containing raw material, followed by a co-precipitation reaction.
  • the nickel-containing raw material may be, for example, nickel-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide or oxyhydroxide, specifically, Ni(OH) 2 , NiO, NiOOH, NiCO 3 ⁇ 2Ni(OH) 2 ⁇ 4H 2 O, NiC 2 O 2 ⁇ 2H 2 O, Ni(NO 3 ) 2 ⁇ 6H 2 O, NiSO 4 , NiSO 4 ⁇ 6H 2 O, fatty acid nickel salt, nickel halide or these It may be a combination, but is not limited thereto.
  • the cobalt-containing raw material may be cobalt-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide or oxyhydroxide, and specifically, Co(OH) 2 , CoOOH, Co(OCOCH 3 ) 2 ⁇ 4H 2 O , Co(NO 3 ) 2 ⁇ 6H 2 O, CoSO 4 , Co(SO 4 ) 2 ⁇ 7H 2 O, or a combination thereof, but is not limited thereto.
  • the manganese-containing raw material may be, for example, manganese-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, oxyhydroxide, or a combination thereof, specifically Mn 2 O 3 , MnO 2 , Mn 3 manganese oxides such as O 4 ; manganese salts such as MnCO 3 , Mn(NO 3 ) 2 , MnSO 4 , manganese acetate, dicarboxylic acid manganese salt, manganese citrate, fatty acid manganese salt; It may be manganese oxyhydroxide, manganese chloride, or a combination thereof, but is not limited thereto.
  • the transition metal solution is prepared by mixing a nickel-containing raw material, a cobalt-containing raw material, and a manganese-containing raw material in a solvent, specifically water, or a mixed solvent of an organic solvent that can be uniformly mixed with water (eg, alcohol). It may be prepared by adding, or may be prepared by mixing an aqueous solution of a nickel-containing raw material, an aqueous solution of a cobalt-containing raw material, and a manganese-containing raw material.
  • a solvent specifically water, or a mixed solvent of an organic solvent that can be uniformly mixed with water (eg, alcohol).
  • the ammonium cation-containing complexing agent may be, for example, NH 4 OH, (NH 4 ) 2 SO 4 , NH 4 NO 3 , NH 4 Cl, CH 3 COONH 4 , NH 4 CO 3 or a combination thereof, However, the present invention is not limited thereto.
  • the ammonium cation-containing complexing agent may be used in the form of an aqueous solution, and as the solvent, water or a mixture of water and an organic solvent that is uniformly miscible with water (specifically, alcohol, etc.) and water may be used.
  • the basic compound may be a hydroxide of an alkali metal or alkaline earth metal such as NaOH, KOH or Ca(OH) 2 , a hydrate thereof, or a combination thereof.
  • the basic compound may also be used in the form of an aqueous solution, and as the solvent, water or a mixture of water and an organic solvent that is uniformly miscible with water (specifically, alcohol, etc.) and water may be used.
  • the basic compound is added to adjust the pH of the reaction solution, and may be added in an amount such that the pH of the metal solution is 11 to 13.
  • the co-precipitation reaction may be performed at a temperature of 40° C. to 70° C. under an inert atmosphere such as nitrogen or argon.
  • particles of nickel-cobalt-manganese hydroxide are generated and precipitated in the reaction solution.
  • concentrations of the nickel-containing raw material, the cobalt-containing raw material, and the manganese-containing raw material it is possible to prepare a precursor having a nickel (Ni) content of 60 mol% or more in the total content of the metal.
  • the precipitated nickel-cobalt-manganese hydroxide particles may be separated according to a conventional method and dried to obtain a nickel-cobalt-manganese precursor.
  • the precursor may be secondary particles formed by agglomeration of primary particles.
  • porous particles may be used as the positive electrode active material precursor.
  • the pH concentration may be controlled to prepare the second cathode active material precursor. Specifically, it may be added in an amount such that the pH is 7 to 9.
  • the lithium raw material may include lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide or oxyhydroxide, and is not particularly limited as long as it is soluble in water.
  • the lithium raw material is Li 2 CO 3 , LiNO 3 , LiNO 2 , LiOH, LiOH ⁇ H 2 O, LiH, LiF, LiCl, LiBr, LiI, CH 3 COOLi, Li 2 O, Li 2 SO 4 , CH 3 COOLi, or Li 3 C 6 H 5 O 7 and the like, and any one or a mixture of two or more thereof may be used.
  • the primary sintering may be sintered at 800 to 1,000° C., more preferably from 830 to 1,000° C., in the case of a high-Ni NCM-based lithium composite transition metal oxide having a nickel (Ni) content of 60 mol% or more. It may be sintered at 980°C, more preferably at 850 to 950°C.
  • the primary firing may be performed at 900 to 1,100° C., more preferably from 930 to 1,070° C. , more preferably at 950 to 1,050 °C.
  • the primary firing may be carried out in an air or oxygen atmosphere, and may be performed for 15 to 35 hours.
  • an additional secondary firing may be performed after the first firing.
  • the secondary sintering may be performed at 600 to 950° C., more preferably 650 to 950° C. in the case of a high-Ni NCM-based lithium composite transition metal oxide having a nickel (Ni) content of 60 mol% or more. It can be calcined at 930°C, more preferably 700 to 900°C.
  • the secondary firing may be performed at 700 to 1,050° C., more preferably at 750 to 1,000° C. , more preferably at 800 to 950 °C.
  • the secondary sintering may be performed under an air or oxygen atmosphere, and may be performed for 10 to 24 hours.
  • a positive electrode for a lithium secondary battery and a lithium secondary battery including the positive electrode active material.
  • the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector and including the positive electrode active material.
  • the positive electrode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or carbon on the surface of aluminum or stainless steel. , nickel, titanium, silver, etc. may be used.
  • the positive electrode current collector may typically have a thickness of 3 to 500 ⁇ m, and may increase the adhesion of the positive electrode active material by forming fine irregularities on the surface of the positive electrode current collector.
  • it may be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven body.
  • the positive active material layer may include a conductive material and a binder together with the above-described positive active material.
  • the conductive material is used to impart conductivity to the electrode, and in the configured battery, it can be used without any particular limitation as long as it has electronic conductivity without causing chemical change.
  • Specific examples include graphite such as natural graphite and artificial graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, summer black, and carbon fiber; metal powders or metal fibers, such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like, and one or a mixture of two or more thereof may be used.
  • the conductive material may be included in an amount of 1 to 30% by weight based on the total weight of the positive active material layer.
  • the binder serves to improve adhesion between the positive electrode active material particles and the adhesive force between the positive electrode active material and the positive electrode current collector.
  • specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC) ), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, or various copolymers thereof, and any one of them or a mixture of two or more thereof may be used.
  • the binder may be included in an amount of 1 to 30% by weight based on the total weight of the positive electrode active material layer.
  • the positive electrode may be manufactured according to a conventional positive electrode manufacturing method except for using the above positive electrode active material. Specifically, it may be prepared by applying the above-described positive electrode active material and, optionally, a composition for forming a positive electrode active material layer including a binder and a conductive material on a positive electrode current collector, followed by drying and rolling. In this case, the types and contents of the positive electrode active material, the binder, and the conductive material are as described above.
  • the solvent may be a solvent generally used in the art, dimethyl sulfoxide (DMSO), isopropyl alcohol (isopropyl alcohol), N-methylpyrrolidone (NMP), acetone (acetone) or water, and the like, and any one of them or a mixture of two or more thereof may be used.
  • the amount of the solvent used is enough to dissolve or disperse the positive electrode active material, the conductive material and the binder in consideration of the application thickness of the slurry and the production yield, and to have a viscosity capable of exhibiting excellent thickness uniformity when applied for the production of the positive electrode thereafter. Do.
  • the positive electrode may be manufactured by casting the composition for forming the positive electrode active material layer on a separate support, and then laminating a film obtained by peeling it from the support on the positive electrode current collector.
  • an electrochemical device including the positive electrode is provided.
  • the electrochemical device may specifically be a battery or a capacitor, and more specifically, may be a lithium secondary battery.
  • the lithium secondary battery specifically includes a positive electrode, a negative electrode positioned to face the positive electrode, a separator and an electrolyte interposed between the positive electrode and the negative electrode, and the positive electrode is as described above.
  • the lithium secondary battery may optionally further include a battery container for accommodating the electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member for sealing the battery container.
  • the negative electrode includes a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector.
  • the negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel surface. Carbon, nickel, titanium, silver, etc. surface-treated, aluminum-cadmium alloy, etc. may be used.
  • the negative electrode current collector may have a thickness of typically 3 to 500 ⁇ m, and similarly to the positive electrode current collector, fine concavities and convexities may be formed on the surface of the current collector to strengthen the bonding force of the negative electrode active material.
  • it may be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven body.
  • the anode active material layer optionally includes a binder and a conductive material together with the anode active material.
  • the anode active material layer may be formed by applying a composition for forming an anode including an anode active material and, optionally, a binder and a conductive material on an anode current collector and drying, or casting the composition for forming a cathode on a separate support, and then , may be produced by laminating a film obtained by peeling from this support onto a negative electrode current collector.
  • a compound capable of reversible intercalation and deintercalation of lithium may be used.
  • Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metal compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; metal oxides capable of doping and dedoping lithium, such as SiO ⁇ (0 ⁇ ⁇ ⁇ 2), SnO 2 , vanadium oxide, and lithium vanadium oxide; Alternatively, a composite including the metallic compound and a carbonaceous material such as a Si-C composite or a Sn-C composite may be used, and any one or a mixture of two or more thereof may be used.
  • a metal lithium thin film may be used as the negative electrode active material.
  • both low crystalline carbon and high crystalline carbon may be used.
  • low crystalline carbon soft carbon and hard carbon are representative, and as high crystalline carbon, amorphous, plate-like, flaky, spherical or fibrous natural or artificial graphite, Kish graphite (Kish) graphite), pyrolytic carbon, mesophase pitch based carbon fiber, meso-carbon microbeads, liquid crystal pitches (Mesophase pitches), and petroleum and coal tar pitch (petroleum or coal tar pitch) High-temperature calcined carbon such as derived cokes) is a representative example.
  • binder and the conductive material may be the same as those described above for the positive electrode.
  • the separator separates the negative electrode and the positive electrode and provides a passage for the movement of lithium ions, and can be used without particular limitation as long as it is usually used as a separator in a lithium secondary battery, especially for the movement of ions in the electrolyte It is preferable to have a low resistance to respect and an excellent electrolyte moisture content.
  • a porous polymer film for example, a porous polymer film made of a polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer, and ethylene/methacrylate copolymer, or these
  • a laminate structure of two or more layers of may be used.
  • a conventional porous nonwoven fabric for example, a nonwoven fabric made of high melting point glass fiber, polyethylene terephthalate fiber, etc. may be used.
  • a coated separator containing a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.
  • examples of the electrolyte used in the present invention include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, and the like, which can be used in the manufacture of lithium secondary batteries, and are limited to these. it is not going to be
  • the electrolyte may include an organic solvent and a lithium salt.
  • the organic solvent may be used without any particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move.
  • ester solvents such as methyl acetate, ethyl acetate, ⁇ -butyrolactone, ⁇ -caprolactone
  • ether solvents such as dibutyl ether or tetrahydrofuran
  • ketone solvents such as cyclohexanone
  • aromatic hydrocarbon-based solvents such as benzene and fluorobenzene
  • carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC)
  • alcohol solvents such as ethyl alcohol and isopropyl alcohol
  • nitriles such as R-CN (R is a C2 to C20 linear, branched or cyclic hydrocarbon group, which may include a double bond
  • carbonate-based solvents are preferable, and cyclic carbonates (eg, ethylene carbonate or propylene carbonate, etc.) having a high dielectric constant capable of increasing the charge/discharge performance of the battery and a low-viscosity linear carbonate-based compound (eg, ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferable.
  • cyclic carbonate and the chain carbonate are mixed in a volume ratio of about 1:1 to about 1:9, the performance of the electrolyte may be excellent.
  • the lithium salt may be used without particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery.
  • the lithium salt is LiPF 6 , LiClO 4 , LiAsF 6 , LiBF 4 , LiSbF 6 , LiAl0 4 , LiAlCl 4 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiN(C 2 F 5 SO 3 ) 2 , LiN(C 2 F 5 SO 2 ) 2 , LiN(CF 3 SO 2 ) 2 .
  • LiCl, LiI, or LiB(C 2 O 4 ) 2 , etc. may be used.
  • the concentration of the lithium salt is preferably used within the range of 0.1 to 2.0M. When the concentration of the lithium salt is included in the above range, the electrolyte may exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions may move effectively.
  • haloalkylene carbonate-based compounds such as difluoroethylene carbonate, pyridine, tri Ethyl phosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imida
  • One or more additives such as taxdine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol or aluminum trichloride may be further included. In this case, the additive may be included in an amount of 0.1 to 5% by weight based on the total weight of the electrolyte.
  • the lithium secondary battery including the positive electrode active material according to the present invention is useful in the field of portable devices such as mobile phones, notebook computers, digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).
  • portable devices such as mobile phones, notebook computers, digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).
  • HEVs hybrid electric vehicles
  • a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.
  • the battery module or battery pack is a power tool (Power Tool); electric vehicles, including electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); Alternatively, it may be used as a power source for any one or more medium-to-large devices in a system for power storage.
  • Power Tool Power Tool
  • electric vehicles including electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs);
  • PHEVs plug-in hybrid electric vehicles
  • Example 1 the first positive electrode active material including large secondary particles having an average diameter (D50) of 15 ⁇ m and the second positive active material including secondary small particles having an average diameter (D50) of 4 ⁇ m were mixed at 60:40. (weight ratio) was mixed and used as a positive electrode active material.
  • the secondary small particles are secondary particles in which 10 or less primary large particles having a diameter of 1 ⁇ m or more are aggregated.
  • a positive electrode active material was prepared as follows:
  • NiSO 4 , CoSO 4 , MnSO 4 Molar ratio of nickel: cobalt: manganese is 0.8 :
  • a 3.2 mol/L concentration of a transition metal solution mixed to be 0.1:0.1 was continuously added to the reactor at 300 mL/hr, and a 28 wt% aqueous ammonia solution was added to the reactor at 42 mL/hr.
  • the speed of the impeller was stirred at 400 rpm, and 40% by weight of sodium hydroxide solution was used to maintain the pH so that the pH was maintained at 11.0.
  • the precursor particles were formed by co-precipitation reaction for 24 hours. The precursor particles were separated, washed, and dried in an oven at 130° C. to prepare a precursor.
  • Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 precursor synthesized by the co-precipitation reaction was mixed with Li 2 CO 3 and Li/Me (Ni, Co, Mn) in a molar ratio of 1.05, followed by heat treatment at 800 ° C. in an oxygen atmosphere for 10 hours to form LiNi 0.8 Co 0.1 Mn 0.1 O 2
  • a lithium composite transition metal oxide first positive active material was prepared.
  • the second positive electrode was prepared in the same manner as in preparing the first positive active material of large particles, except that the pH was controlled to 9 during the coprecipitation reaction in the precursor preparation, the coprecipitation reaction time was changed to 10 hours, and the heat treatment conditions were changed to 850° C.
  • the active material was synthesized.
  • Example 2 the first positive active material including large secondary particles having an average diameter (D50) of 10 ⁇ m and the second positive active material including secondary small particles having an average diameter (D50) of 4 ⁇ m were mixed at 60:40. (weight ratio) was mixed and used as a positive electrode active material.
  • the secondary small particles are secondary particles in which 10 or less primary large particles having a diameter of 1 ⁇ m or more are aggregated.
  • a positive electrode active material was prepared as follows:
  • the first positive active material was prepared in the same manner as in Example 1, except that the co-precipitation time was changed to 15 hours in the preparation of the first positive active material of large particles.
  • the second positive active material was synthesized in the same manner as in Example 1.
  • Comparative Example 1 80: a first positive active material including large secondary particles having an average diameter (D50) of 15 ⁇ m, and a second positive active material including small secondary particles having an average diameter (D50) of 4 ⁇ m: 20 (weight ratio) was mixed and used as a positive electrode active material.
  • the secondary particle small particle is a secondary particle in which primary fine particles having a diameter of 0.5 ⁇ m or less are aggregated.
  • a positive electrode active material was prepared as follows:
  • the first positive active material was prepared in the same manner as in the preparation of the first positive active material of large particles in Example 1.
  • the second cathode active material was synthesized in the same manner as in Example 1, except that in the preparation of the second cathode active material of small particles, the pH was controlled to 11 when synthesizing the precursor and the heat treatment was changed to 800°C.
  • a cathode active material was prepared in the same manner as in Example 1, except that the weight ratio of the secondary large particles to the secondary small particles was controlled to 80:20 instead of 60:40.
  • the secondary small particles are secondary particles in which 10 or less primary large particles having a diameter of 1 ⁇ m or more are aggregated.
  • a positive electrode active material was prepared in the same manner as in Comparative Example 1, except that the weight ratio of the secondary large particles and the secondary particles small particles was controlled to 60:40 instead of 80:20.
  • the secondary particle small particle is a secondary particle in which primary fine particles having a diameter of 0.5 ⁇ m or less are aggregated.
  • a first positive active material including large secondary particles having an average diameter (D50) of 10 ⁇ m and a second positive active material including small secondary particles having an average diameter (D50) of 4 ⁇ m were prepared by mixing 80: 20 (weight ratio) was mixed and used as a positive electrode active material.
  • the secondary particle small particle is a secondary particle in which primary fine particles having a diameter of 0.5 ⁇ m or less are aggregated.
  • a positive electrode active material was prepared as follows:
  • the first positive active material was prepared in the same manner as in the preparation of the first positive active material of large particles in Example 2.
  • the second positive active material was synthesized in the same manner as in the preparation of the second positive active material of Comparative Example 1.
  • a cathode active material was prepared in the same manner as in Example 2, except that the weight ratio of the secondary large particles and the secondary particles was changed to 80:20 instead of 60:40.
  • Comparative Example 6 a cathode active material was prepared in the same manner as in Comparative Example 4, except that the weight ratio of the secondary large particles to the secondary particles was controlled to 60:40 instead of 80:20.
  • the first positive active material including large secondary particles having an average diameter (D50) of 8 ⁇ m and the second positive active material including small secondary particles having an average diameter (D50) of 4 ⁇ m were mixed at 80:20. (weight ratio) was mixed and used as a positive electrode active material.
  • the secondary particle small particle is a secondary particle in which primary fine particles having a diameter of 0.5 ⁇ m or less are aggregated.
  • a positive electrode active material was prepared as follows:
  • the first positive active material was prepared in the same manner as in Example 1, except that the co-precipitation time was changed to 10 hours in the preparation of the first positive active material of large particles.
  • the second positive active material was synthesized in the same manner as in Comparative Example 1.
  • the first positive active material including large secondary particles having an average diameter (D50) of 8 ⁇ m and the second positive active material including small secondary particles having an average diameter (D50) of 4 ⁇ m were mixed at 80:20. (weight ratio) was mixed and used as a positive electrode active material.
  • the secondary small particles are secondary particles in which 10 or less primary large particles having a diameter of 1 ⁇ m or more are aggregated.
  • a positive electrode active material was prepared as follows:
  • the first positive active material was prepared in the same manner as in Comparative Example 7.
  • the second positive active material was synthesized in the same manner as in Example 1.
  • Comparative Example 9 a cathode active material was prepared in the same manner as in Comparative Example 7, except that the weight ratio of the secondary large particles to the secondary particles was controlled to be 60:40 instead of 80:20.
  • Comparative Example 10 only the first positive active material including secondary large particles having an average diameter (D50) of 15 ⁇ m was used.
  • a positive electrode active material was prepared as follows:
  • the first positive active material was synthesized in the same manner as in the preparation of the first positive active material of large particles in Example 1.
  • Comparative Example 11 only the first positive active material including secondary large particles having an average diameter (D50) of 10 ⁇ m was used.
  • a positive electrode active material was prepared as follows:
  • the first positive active material was synthesized in the same manner as in the preparation of the first positive active material of large particles of Example 2.
  • Comparative Example 12 only the first positive active material including secondary large particles having an average diameter (D50) of 8 ⁇ m was used.
  • a positive electrode active material was prepared as follows:
  • the first positive active material was synthesized in the same manner as in the preparation of the first positive active material of the large particles of Comparative Example 7.
  • Comparative Example 13 is a case in which only the first positive active material including secondary small particles having an average diameter (D50) of 4 ⁇ m is used.
  • the secondary small particles are secondary particles in which 10 or less primary large particles having a diameter of 1 ⁇ m or more are aggregated.
  • a positive electrode active material was prepared as follows:
  • the first positive active material was synthesized in the same manner as in the preparation of the second positive active material of small particles of Example 1.
  • the positive active materials prepared in Examples 1 and 2 and Comparative Examples 1 to 13 were mixed with each positive active material, carbon black conductive material, and PVdF binder in an N-methylpyrrolidone solvent in a weight ratio of 96:2:2. to prepare a positive electrode slurry, which was applied to one surface of an aluminum current collector, dried at 100° C., and rolled to a porosity of 25% to prepare a positive electrode.
  • the prepared positive electrode was heat-treated at 500° C. in atmospheric conditions for 10 hours to remove the binder and the conductive material. Thereafter, the remaining cathode active material powder was recovered and particle size distribution was measured, and the results are shown in Tables 2 to 4 below.
  • Examples 1 and 3 of Table 2 use the same large secondary particles of 15 ⁇ m in size, but in Example 1, secondary small particles including primary large particles were used in a bimodal manner, and Comparative Example 3 is a case in which secondary particle small particles including primary fine particles are used in a bimodal manner.
  • the fine powder of less than 1 ⁇ m during rolling is significantly lower in Example 1 than in Comparative Example 3.
  • Example 1 and Comparative Example 2 of Table 2 the same secondary large particles and secondary small particles were used, respectively.
  • the weight ratio of the secondary large particles: the secondary small particles is 60: 40, and in the case of Comparative Example 2, 80: 20.
  • the ratio of secondary small particles increased, the fine powder formation ratio was significantly lowered from 6.7% to 2.1%.
  • Comparative Example 1 and Comparative Example 3 were compared, they were prepared in the same ratio as in Examples 1 and 2, but the secondary containing primary fine particles instead of the secondary small particles containing primary large particles. This is a case of using small particles as bimodal.
  • the ratio of the secondary small particles including the conventional primary fine particles increased, it was confirmed that the fine powder formation ratio was rather increased from 11.6% to 16%.
  • Example 2 and Comparative Example 6 of Table 3 use the same large secondary particles of 10 ⁇ m in size, but in Example 2, secondary small particles including primary large particles were used in a bimodal manner, and Comparative Example 6 is a case in which secondary particle small particles including primary fine particles are used in a bimodal manner.
  • Table 3 the fine powder of less than 1 ⁇ m during rolling is significantly lower in Example 2 than in Comparative Example 6.
  • Example 2 and Comparative Example 5 of Table 3 the same secondary large particles and secondary small particles were used, respectively.
  • the weight ratio of the secondary large particles: the secondary small particles is 60:40, and in the case of Comparative Example 5, 80:20.
  • Comparative Example 4 and Comparative Example 6 Comparative Examples 5 and 2 were prepared in the same ratio as in Example 2, but instead of the secondary small particles including the primary large particles, the secondary containing the conventional primary fine particles This is a case of using small particles as bimodal.
  • Table 3 as the ratio of the secondary small particles including the conventional primary fine particles increased, it was confirmed that the fine powder formation ratio was rather increased from 12.5% to 14.1%.
  • Comparative Example 12 Comparative Example 7 Comparative Example 9 Comparative Example 8 Comparative Example 13 Secondary large particles: weight ratio of secondary small particles 10:0 8:2 6:4 8:2 0:10 Less than 1 ⁇ m ratio (%) 15.1 13.9 15.0 9.1 6.2
  • Comparative Example 9 of Table 4 uses large secondary particles having a size of 8 ⁇ m, but is a case in which small secondary particles including primary fine particles are used in a bimodal manner. Comparing Comparative Example 9 and Comparative Example 7, although prepared in the same ratio as in Comparative Example 8, the secondary small particles containing the conventional primary fine particles were bimodal instead of the secondary small particles containing the primary large particles. in case it was used. As can be seen from Table 4, as the ratio of the secondary small particles including the conventional primary fine particles increased, it was confirmed that the fine powder formation ratio was rather increased from 13.9% to 15.0%.
  • Comparative Examples 7 to 9 showed a lower fine powder ratio compared to Comparative Example 12 in which only the secondary large particles were used alone, but as in Comparative Example 13, higher than when only the secondary small particles including the primary large particles were used alone showed differential.
  • the peak intensity of the secondary large particles was measured as follows.
  • Comparative Example 1 Comparative Example 3 Comparative Example 2
  • Example 1 Secondary large particles: weight ratio of secondary small particles 8:2 6:4 8:2 6:4 Large particle peak intensity decrease (%) Before - After 3 1.1 1.8 0
  • Comparative Examples 1 to 3 and Example 1 of Table 5 are all cases in which secondary large particles and secondary small particles having a size of 15 ⁇ m were used in a bimodal manner. However, in Comparative Examples 1 and 3, small secondary particles were used, and the primary particles constituting the secondary particles were primary fine particles having a diameter of 0.5 ⁇ m or less. On the other hand, in Comparative Examples 2 and 1, secondary small particles in which 10 or less primary large particles having a diameter of 1 ⁇ m or more were aggregated were used.
  • Comparative Examples 4 to 6 and Example 2 of Table 6 are cases in which secondary large particles and secondary small particles having a size of 10 ⁇ m are used in a bimodal manner. However, in Comparative Examples 4 and 6, small secondary particles were used, and the primary particles constituting the secondary particles were primary fine particles having a diameter of 0.5 ⁇ m or less. On the other hand, in Comparative Examples 5 and 2, secondary small particles in which primary large particles having a diameter of 1 ⁇ m or more are aggregated are used.
  • Comparative Example 7 Comparative Example 9 Comparative Example 8 Secondary large particles: weight ratio of secondary small particles 8:2 6:4 8:2 Large particle peak intensity decrease (%) Before - After 6.1 3.3 4.2
  • Comparative Examples 7 to 9 of Table 7 all of the secondary large particles and secondary small particles having a size of 8 ⁇ m were used in a bimodal manner. However, in Comparative Examples 7 and 9, small secondary particles were used, and the primary particles constituting the secondary particles were primary fine particles having a diameter of 0.5 ⁇ m or less. On the other hand, in Comparative Example 8, secondary small particles in which 10 or less primary large particles having a diameter of 1 ⁇ m or more were aggregated were used.
  • Each of the positive electrode active material, carbon black conductive material, and PVdF binder prepared in Examples and Comparative Examples was mixed in an N-methylpyrrolidone solvent in a weight ratio of 96:2:2 to prepare a positive electrode slurry, which After coating on the entire surface, drying at 100 °C, and rolling to prepare a positive electrode.
  • lithium metal As the negative electrode, lithium metal was used.
  • An electrode assembly was prepared by interposing a separator of porous polyethylene between the positive electrode and the negative electrode prepared as described above, the electrode assembly was placed inside the case, and the electrolyte was injected into the case to prepare a lithium secondary battery.
  • the prepared lithium secondary battery half cell was charged at 45°C in CC-CV mode at 0.7C to 4.4V, and discharged to 3.0V at a constant current of 0.5C to conduct 30 charge/discharge experiments.
  • the capacity retention rate at the time of proceeding was measured to evaluate the lifespan characteristics. The results are shown in Table 8 below.
  • Example 1 and Comparative Examples 1 to 3 using the same large secondary particles of 15 ⁇ m in size the secondary small particles including the primary large particles and the existing secondary large particles were 40 Example 1 used in a ratio of : 60 showed the highest capacity retention rate. This tendency is also confirmed in Example 2 and Comparative Example 5 to which secondary large particles of 10 ⁇ m in size are applied, and Comparative Example 8 in which secondary large particles of 8 ⁇ m in size are applied.
  • Example 2 Large particle peak intensity decrease (%) Before - After 0 1.7

Abstract

The present invention relates to a positive electrode active material, a method for preparing same, and a lithium secondary battery comprising same, the positive electrode active material comprising one or more secondary particles comprising an aggregate of primary macroparticles. According to an embodiment of the present invention, the positive electrode active material comprises secondary particles having enhanced surface resistance compared to when applying existing single particles. According to an embodiment of the present invention, the nickel-based positive electrode active material has reduced particle comminution and excellent charging/discharging cycle characteristics during rolling of the positive electrode active material.

Description

리튬 이차 전지용 양극 활물질, 그 제조방법 및 이를 포함하는 리튬 이차 전지Cathode active material for lithium secondary battery, manufacturing method thereof, and lithium secondary battery comprising same
본 발명은 1차 거대 입자를 포함하는 리튬 이차 전지용 양극 활물질 및 그 제조방법에 관한 것이다. The present invention relates to a cathode active material for a lithium secondary battery comprising primary large particles and a method for manufacturing the same.
본 출원은 2020년 11월 5일 자로 출원된 한국 특허출원번호 제 10-2020-0146992호에 대한 우선권주장출원으로서, 해당 출원의 명세서에 개시된 모든 내용은 인용에 의해 본 출원에 원용된다.This application is an application claiming priority to Korean Patent Application No. 10-2020-0146992 filed on November 5, 2020, and all contents disclosed in the specification of the application are incorporated herein by reference.
최근 휴대전화, 노트북 컴퓨터, 전기 자동차 등 전지를 사용하는 전자기구의 급속한 보급에 수반하여 소형 경량이면서도 상대적으로 고용량인 이차 전지의 수요가 급속히 증대되고 있다. 특히, 리튬 이차 전지는 경량이고 고에너지 밀도를 가지고 있어 휴대 기기의 구동 전원으로서 각광을 받고 있다. 이에 따라, 리튬 이차 전지의 성능향상을 위한 연구개발 노력이 활발하게 진행되고 있다.Recently, with the rapid spread of electronic devices using batteries, such as mobile phones, notebook computers, and electric vehicles, the demand for small, lightweight and relatively high-capacity secondary batteries is rapidly increasing. In particular, a lithium secondary battery has been in the spotlight as a driving power source for a portable device because it is lightweight and has a high energy density. Accordingly, research and development efforts for improving the performance of lithium secondary batteries are being actively conducted.
리튬 이차 전지는 리튬 이온의 삽입(intercalation) 및 탈리(deintercalation)가 가능한 활물질로 이루어진 양극과 음극 사이에 유기 전해액 또는 폴리머 전해액을 충전시킨 상태에서 리튬 이온이 양극 및 음극에서 삽입/탈리 될 때의 산화와 환원 반응에 의해 전기 에너지 와 화학 에너지의 변환이 일어난다. In a lithium secondary battery, an organic electrolyte or polymer electrolyte is charged between a positive electrode and a negative electrode made of an active material capable of intercalation and deintercalation of lithium ions, and lithium ions are inserted/deintercalated from the positive electrode and the negative electrode. The conversion of electrical energy and chemical energy occurs by a reduction reaction with
리튬 이차 전지의 양극 활물질로는 리튬 코발트 산화물(LiCoO2), 리튬 니켈 산화물(LiNiO2), 리튬 망간 산화물(LiMnO2 또는 LiMn2O4 등), 리튬 인산철 화합물(LiFePO4) 등이 사용된다. 이 중에서도 리튬 코발트 산화물(LiCoO2)은 작동 전압이 높고 용량 특성이 우수한 장점이 있어, 널리 사용되고 있으며, 고전압용 양극 활물질로 적용되고 있다. 그러나, 코발트(Co)의 가격 상승 및 공급 불안정 때문에 전기 자동차 등과 같은 분야의 동력원으로 대량 사용하기에 한계가 있어, 이를 대체할 수 있는 양극 활물질 개발의 필요성이 대두되었다. 이에 따라, 코발트(Co)의 일부를 니켈(Ni)과 망간(Mn)으로 치환한 니켈코발트망간계 리튬 복합 전이금속 산화물(이하 간단히 'NCM계 리튬 복합 전이금속 산화물'이라 함)이 개발되었다. As a positive active material of a lithium secondary battery, lithium cobalt oxide (LiCoO 2 ), lithium nickel oxide (LiNiO 2 ), lithium manganese oxide (LiMnO 2 or LiMn 2 O 4 , etc.), lithium iron phosphate compound (LiFePO 4 ), etc. are used. . Among them, lithium cobalt oxide (LiCoO 2 ) has the advantage of high operating voltage and excellent capacity characteristics, and is widely used, and is applied as a high-voltage positive electrode active material. However, there is a limit to mass use as a power source in fields such as electric vehicles due to an increase in the price of cobalt (Co) and unstable supply, and the need to develop a positive electrode active material that can replace it has emerged. Accordingly, a nickel-cobalt-manganese-based lithium composite transition metal oxide (hereinafter simply referred to as 'NCM-based lithium composite transition metal oxide') in which a part of cobalt (Co) is substituted with nickel (Ni) and manganese (Mn) has been developed.
한편, 양극 활물질은 출력 및 압연 밀도를 높이고자 크기가 다른 2가지의 양극 활물질을 사용하는 경우가 대부분이다. 이 때, 양극 활물질은 1차 입자가 모여서 형성된 2차 입자일 수 있다. 그러나, 1차 입자가 모여서 형성된 2차 입자를 이용하여 양극을 구성하는 경우에는, 전극 제조 과정 중 하나인 압연 단계에서 1차 입자 및/또는 2차 입자의 깨짐으로 인해, 전극 내 전자의 이동 경로가 손실되고 전해액과의 부반응이 일어날 수 있는 표면적이 넓어지는 문제가 있다. 결과적으로 수명 특성이 열위에 놓이는 문제가 있다. Meanwhile, in most cases, two types of positive electrode active materials having different sizes are used to increase output and rolling density. In this case, the positive electrode active material may be secondary particles formed by gathering primary particles. However, in the case of configuring the positive electrode using secondary particles formed by gathering primary particles, due to the breaking of primary particles and/or secondary particles in the rolling step, which is one of the electrode manufacturing processes, the movement path of electrons in the electrode is lost and the surface area where side reactions with the electrolyte can occur increases. As a result, there is a problem in that the life characteristics are inferior.
본 발명이 해결하고자 하는 과제는, 상기 과제를 해결하기 위한 것으로, 입자 크기 및 형상을 제어하여 압연시의 입자 깨짐을 최소화할 수 있는 양극 활물질을 제공하는 것이다. An object of the present invention is to solve the above problems, and to provide a positive electrode active material capable of minimizing particle breakage during rolling by controlling particle size and shape.
이에 따라 양극 활물질의 압연시 입자 깨짐이 감소되고, 수명 특성이 개선된 니켈계 양극 활물질을 제공하는 것이다. Accordingly, it is an object to provide a nickel-based positive electrode active material having reduced particle breakage during rolling of the positive electrode active material and improved lifespan characteristics.
본 발명의 일 측면은 하기 구현예들에 따른 양극 활물질을 제공한다.One aspect of the present invention provides a cathode active material according to the following embodiments.
제1 구현예는, A first embodiment is
대입자의 제1 양극 활물질 및 소입자의 제2 양극 활물질을 포함하는 리튬 이차 전지용 양극 활물질이며, It is a positive electrode active material for a lithium secondary battery comprising a first positive electrode active material of large particles and a second positive electrode active material of small particles,
상기 제1 양극 활물질은, 1차 미세(micro) 입자의 응집체를 포함하는 적어도 하나의 2차 대입자를 포함하며,The first positive active material includes at least one secondary large particle including an aggregate of primary micro particles,
상기 제2 양극 활물질은, 1차 거대(macro) 입자의 응집체를 포함하는 적어도 하나의 2차 소입자를 포함하며, The second positive active material includes at least one secondary small particle including an aggregate of primary macro particles,
상기 1차 거대 입자의 평균 입경(D50)은 1 ㎛ 이상이며,The average particle diameter (D50) of the primary large particles is 1 μm or more,
상기 제1 양극 활물질의 평균 입경(D50)/상기 제2 양극 활물질의 평균 입경(D50)의 비는 2 이상이며, The ratio of the average particle diameter (D50) of the first positive electrode active material / the average particle diameter (D50) of the second positive electrode active material is 2 or more,
상기 제1 양극 활물질과 상기 제2 양극 활물질의 중량비는 50 : 50 내지 70 : 30인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질에 관한 것이다. The weight ratio of the first positive active material and the second positive active material is 50: 50 to 70: 30, it relates to a lithium secondary battery positive electrode active material, characterized in that.
제2 구현예는, 제1 구현예에 있어서, In the second embodiment, according to the first embodiment,
상기 1차 거대 입자의 평균 직경(D50)은 2 ㎛ 이상이며, The average diameter (D50) of the primary large particles is 2 μm or more,
상기 1차 거대 입자의 평균 입경(D50)/상기 1차 거대 입자의 평균 결정 크기(crystal size)의 비는 2 이상인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질에 관한 것이다. The ratio of the average particle diameter (D50) of the primary large particles to the average crystal size of the primary large particles is 2 or more.
제3 구현예는, 제1 또는 제2 구현예에 있어서, A third embodiment, according to the first or second embodiment,
상기 제1 양극 활물질의 평균 입경(D50)은 10 ㎛ 내지 20 ㎛ 인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질에 관한 것이다. The first positive electrode active material has an average particle diameter (D50) of 10 μm to 20 μm.
제4 구현예는, 제1 내지 제3 구현예 중 어느 한 구현예에 있어서, A fourth embodiment, according to any one of the first to third embodiments,
상기 제2 양극 활물질의 평균 입경(D50)은 3 ㎛ 내지 6 ㎛ 인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질에 관한 것이다. The second positive electrode active material has an average particle diameter (D50) of 3 μm to 6 μm.
제5 구현예는, 제1 내지 제4 구현예 중 어느 한 구현예에 있어서, A fifth embodiment, according to any one of the first to fourth embodiments,
상기 제1 양극 활물질의 1차 미세 입자의 평균 입경(D50)은 0.1 ㎛ 내지 0.5 ㎛ 인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질에 관한 것이다. The average particle diameter (D50) of the primary fine particles of the first positive electrode active material relates to a positive electrode active material for a lithium secondary battery, characterized in that 0.1 μm to 0.5 μm.
제6 구현예는, 제1 내지 제5 구현예 중 어느 한 구현예에 있어서, A sixth embodiment, according to any one of the first to fifth embodiments,
상기 제2 양극 활물질은, 상기 2차 소입자를 압연시 상기 1차 거대 입자가 떨어져 나가며, 상기 1차 거대 입자 자체는 깨지지 않는 것을 특징으로 하는 리튬 이차 전지용 양극 활물질에 관한 것이다. The second positive electrode active material relates to a positive electrode active material for a lithium secondary battery, characterized in that the primary large particles fall off when the secondary small particles are rolled, and the primary large particles themselves are not broken.
제7 구현예는, 제6 구현예에 있어서, The seventh embodiment, according to the sixth embodiment,
상기 압연은 상기 양극 활물질을 포함하는 양극의 기공도가 15 내지 30%가 되도록 수행되는 것을 특징으로 하는 리튬 이차 전지용 양극 활물질에 관한 것이다. The rolling relates to a positive electrode active material for a lithium secondary battery, characterized in that the porosity of the positive electrode including the positive electrode active material is 15 to 30%.
제8 구현예는, 제1 내지 제7 구현예 중 어느 한 구현예에 있어서, The eighth embodiment, according to any one of the first to seventh embodiments,
상기 1차 거대 입자의 평균 결정 크기는 150 nm 이상인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질에 관한 것이다. The average crystal size of the primary large particles relates to a cathode active material for a lithium secondary battery, characterized in that 150 nm or more.
제9 구현예는, 제1 내지 제8 구현예 중 어느 한 구현예에 있어서, A ninth embodiment, according to any one of the first to eighth embodiments,
상기 2차 소입자의 평균 입경(D50)/상기 1차 거대 입자의 평균 입경(D50)의 비는 2 내지 4배인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질에 관한 것이다. The ratio of the average particle diameter (D50) of the secondary small particles to the average particle diameter (D50) of the primary large particles is 2 to 4 times.
제10 구현예는, 제1 내지 제9 구현예 중 어느 한 구현예에 있어서, The tenth embodiment, according to any one of the first to ninth embodiments,
상기 제1 및 제2 양극 활물질은 니켈계 리튬 전이금속 산화물을 포함하는 것을 특징으로 하는 리튬 이차 전지용 양극 활물질에 관한 것이다. The first and second positive electrode active materials relate to a positive electrode active material for a lithium secondary battery, characterized in that it includes a nickel-based lithium transition metal oxide.
제11 구현예는, 제10 구현예에 있어서, The eleventh embodiment, according to the tenth embodiment,
상기 니켈계 리튬 전이금속 산화물은, Li(1+a)Ni(1-(a+x+y+w))CoxM1yM2wO2 (여기에서, 0≤a≤0.5, 0≤x≤0.35, 0≤y≤0.35, 0≤w≤0.1, 0≤a+x+y+w≤0.7, M1은 Mn 및 Al으로 이루어지는 군으로부터 선택되는 적어도 1종, M2는 Ba, Ca, Zr, Ti, Mg, Ta, Nb 및 Mo으로 이루어지는 군으로부터 선택되는 적어도 1종)을 포함하는 것을 특징으로 하는 리튬 이차 전지용 양극 활물질에 관한 것이다. The nickel-based lithium transition metal oxide is, Li (1+a) Ni (1-(a+x+y+w)) Co x M1 y M2 w O 2 (here, 0≤a≤0.5, 0≤x ≤0.35, 0≤y≤0.35, 0≤w≤0.1, 0≤a+x+y+w≤0.7, M1 is at least one selected from the group consisting of Mn and Al, M2 is Ba, Ca, Zr, Ti, Mg, Ta, at least one selected from the group consisting of Nb and Mo) relates to a cathode active material for a lithium secondary battery, characterized in that it contains.
제12 구현예는, 제1 내지 제11 구현예 중 어느 한 구현예에 있어서, The twelfth embodiment, according to any one of the first to eleventh embodiments,
상기 양극 활물질은 상기 양극 활물질을 포함하는 양극의 기공도가 15 내지 30%인 조건에서, PSD 분포에서, 1 ㎛ 미만의 입자 비율이 10% 미만인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질에 관한 것이다.The positive active material relates to a positive electrode active material for a lithium secondary battery, characterized in that the ratio of particles smaller than 1 μm in PSD distribution is less than 10% under the condition that the porosity of the positive electrode including the positive active material is 15 to 30%.
제13 구현예는, 제1 내지 제12 구현예 중 어느 한 구현예에 있어서, A thirteenth embodiment, according to any one of the first to twelfth embodiments,
상기 양극 활물질은, 상기 양극 활물질을 포함하는 양극의 기공도가 15 내지 30%이 되도록 가압할 때, 가압 전/후, 상기 2차 대입자의 피크 강도(peak intensity) 감소율이 2% 미만인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질에 관한 것이다.When the positive electrode active material is pressurized so that the porosity of the positive electrode including the positive active material is 15 to 30%, the peak intensity decrease rate of the secondary large particles before and after the pressurization is less than 2%, characterized in that It relates to a positive electrode active material for a lithium secondary battery.
본 발명의 일 측면은 하기 구현예에 따른 리튬 이차 전지용 양극을 제공한다. One aspect of the present invention provides a positive electrode for a lithium secondary battery according to the following embodiments.
제14 구현예는, 전술한 구현예 중 어느 한 구현예에 따른 양극 활물질을 포함하는 리튬 이차 전지용 양극을 제공한다. A fourteenth embodiment provides a positive electrode for a lithium secondary battery comprising the positive electrode active material according to any one of the above-described embodiments.
본 발명의 일 측면은 하기 구현예에 따른 리튬 이차 전지를 제공한다. One aspect of the present invention provides a lithium secondary battery according to the following embodiments.
제15 구현예는, 전술한 구현예 중 어느 한 구현예에 따른 양극 활물질을 포함하는 리튬 이차 전지를 제공한다. A fifteenth embodiment provides a lithium secondary battery including the positive electrode active material according to any one of the above embodiments.
본 발명의 일 실시예에 따르면, 기존과 같이 대입경을 가지는 2차 입자, 소입경을 가지는 2차 입자를 바이모달로 사용한 경우에 비해 압연시 입자 깨짐이나 미분 발생량이 현저히 억제되어 수명특성을 크게 향상시킬 수 있다. According to an embodiment of the present invention, compared to the case of using secondary particles having a large particle diameter and secondary particles having a small particle diameter as in the prior art in a bimodal manner, the amount of particle breakage or fine powder generation during rolling is significantly suppressed, thereby greatly improving the lifespan characteristics. can be improved
본 발명의 일 실시예에 따르면, 기존의 1차 거대 입자로 구성된 2차 소입자를 단독으로 사용한 경우에 비해 압연시 입자 깨짐이나 미분 발생량이 현저히 억제되어 수명특성을 크게 향상시킬 수 있다.According to an embodiment of the present invention, compared to the case of using the existing secondary small particles composed of the primary large particles alone, the amount of particle breakage or fine powder generation during rolling is significantly suppressed, thereby greatly improving the lifespan characteristics.
본 명세서에 첨부되는 도면들은 본 발명의 바람직한 실시예를 예시한 것이며, 전술한 발명의 내용과 함께 본 발명의 기술 사상을 더욱 잘 이해시키는 역할을 하는 것이므로, 본 발명은 그러한 도면에 기재된 사항에만 한정되어 해석되는 것은 아니다. 한편, 본 명세서에 수록된 도면에서의 요소의 형상, 크기, 축척 또는 비율 등은 보다 명확한 설명을 강조하기 위해서 과장될 수 있다. The drawings attached to the present specification illustrate preferred embodiments of the present invention, and serve to better understand the technical spirit of the present invention together with the above-described content of the present invention, so the present invention is limited only to the matters described in such drawings is not interpreted as On the other hand, the shape, size, scale, or ratio of elements in the drawings included in this specification may be exaggerated to emphasize a clearer description.
도 1은 비교예 1에 따른 양극 활물질을 적용한 전극의 단면을 찍은 SEM 이미지이다. 1 is a SEM image of a cross-section of an electrode to which a positive active material according to Comparative Example 1 is applied.
도 2는 비교예 2에 따른 양극 활물질을 적용한 전극의 단면을 찍은 SEM 이미지이다. 2 is a SEM image of a cross-section of an electrode to which a positive active material according to Comparative Example 2 is applied.
도 3은 본 발명의 실시예 1에 따른 양극 활물질을 적용한 전극의 단면을 찍은 SEM 이미지이다.3 is a SEM image of a cross-section of an electrode to which a positive active material according to Example 1 of the present invention is applied.
이하 본 발명의 구현예를 상세히 설명한다. 이에 앞서, 본 명세서 및 청구범위에 사용된 용어나 단어는 통상적이거나 사전적인 의미로 한정해서 해석되어서는 아니되며, 발명자는 그 자신의 발명을 가장 최선의 방법으로 설명하기 위해 용어의 개념을 적절하게 정의할 수 있다는 원칙에 입각하여 본 발명의 기술적 사상에 부합하는 의미와 개념으로 해석되어야만 한다. 따라서, 본 명세서에 기재된 실시예에 기재된 구성은 본 발명의 가장 바람직한 일 실시예에 불과할 뿐이고 본 발명의 기술적 사상을 모두 대변하는 것은 아니므로, 본 출원시점에 있어서 이들을 대체할 수 있는 다양한 균등물과 변형예들이 있을 수 있음을 이해하여야 한다.Hereinafter, embodiments of the present invention will be described in detail. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention. Therefore, the configuration described in the embodiment described in this specification is only the most preferred embodiment of the present invention and does not represent all the technical spirit of the present invention, so at the time of the present application, various equivalents and It should be understood that there may be variations.
본원 명세서 전체에서, 어떤 부분이 어떤 구성 요소를 「포함한다」고 할 때, 이는 특별히 반대되는 기재가 없는 한 다른 구성 요소를 제외하는 것이 아니라 다른 구성요소를 더 포함할 수 있는 것을 의미한다. Throughout this specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.
본 명세서 및 청구범위에 있어서, "다수의 결정립을 포함한다" 함은 특정 범위의 평균 결정 크기를 갖는 둘 이상의 결정 입자가 모여서 이루어지는 결정체를 의미한다. 이때 상기 결정립의 결정 크기는 Cu Kα X선(X-ray)에 의한 X선 회절 분석(XRD)을 이용하여 정량적으로 분석될 수 있다. 구체적으로는 제조된 입자를 홀더에 넣어 X선을 상기 입자에 조사해 나오는 회절 격자를 분석함으로써, 결정립의 평균 결정 크기를 정량적으로 분석 할 수 있다. In the present specification and claims, "including a plurality of crystal grains" means a crystal formed by gathering two or more crystal grains having an average crystal size in a specific range. In this case, the crystal size of the crystal grains may be quantitatively analyzed using X-ray diffraction analysis (XRD) by Cu Kα X-rays. Specifically, the average crystal size of the crystal grains can be quantitatively analyzed by putting the prepared particles in a holder and analyzing the diffraction grating that irradiates X-rays to the particles.
예를 들어, 다음과 같이 분석할 수 있다. For example, it can be analyzed as follows.
먼저, 샘플링은 일반 분말용 홀더 가운데 패인 홈에 시료를 넣고 슬라이드 글라스를 이용하여 표면을 고르게, 높이를 홀더 가장자리와 같게 하여 준비한다. LynxEye XE-T position sensitive detector 가 장착된 Bruker D8 Endeavor (Cu Kα, λ= 1.54 Å)를 이용, FDS 0.5°, 2-theta 15도에서 90도 영역에 대해 step size 0.02도로 total scan time이 ~20분 되게 시료를 측정한다. 측정된 data에 대해 각 site에서의 charge (transition metal site에서의 metal들은 +3, Li site의 Ni은 +2)와 cation mixing을 고려하여 Rietveld refinement를 수행한다. Crystallite size 분석 시 instrumental broadening은 Bruker TOPAS program에 implement 되어 있는 Fundamental Parameter Approach (FPA)를 이용하여 고려하고, fitting 시 측정 범위의 전체 peak들이 사용된다. Peak shape은 TOPAS에서 사용 가능한 peak type 중 FP (First Principle)로 Lorenzian contribution 만 사용되어 fitting되었고, 이 때 strain은 고려하지 않았다. 상기 방법을 통해 구조 분석을 진행하였고, 결정립의 평균 결정 크기를 정량적으로 분석할 수 있다.First, for sampling, place a sample in a groove in the middle of a general powder holder, use a slide glass to make the surface even, and prepare the height equal to the edge of the holder. Using a Bruker D8 Endeavor (Cu Kα, λ= 1.54 Å) equipped with LynxEye XE-T position sensitive detector, FDS 0.5°, 2-theta 15° to 90° step size 0.02°, total scan time is ~20 Measure the sample in minutes. For the measured data, Rietveld refinement is performed considering charge (+3 for metals at transition metal site, +2 for Ni at Li site) and cation mixing at each site. When analyzing crystallite size, instrumental broadening is considered using the Fundamental Parameter Approach (FPA) implemented in the Bruker TOPAS program, and the entire peaks of the measurement range are used during fitting. The peak shape was fitted using only Lorenzian contribution as FP (First Principle) among the peak types available in TOPAS, and strain was not considered at this time. Structural analysis was performed through the above method, and the average crystal size of grains can be quantitatively analyzed.
명세서 및 청구범위에 있어서, D50은 입자크기 분포의 50% 기준에서의 입자크기로 정의될 수 있으며, 레이저 회절법(laser diffraction method)을 이용하여 측정될 수 있다. 예를 들어, 상기 양극 활물질의 평균 입경(D50)의 측정 방법은, 양극 활물질의 입자를 분산매 중에 분산시킨 후, 시판되는 레이저 회절 입도 측정 장치(예를 들어, Microtrac MT 3000)에 도입하여 약 28kHz의 초음파를 출력 60W로 조사한 후, 측정 장치에 있어서의 체적 누적량의 50%에 해당하는 평균 입경(D50)을 산출할 수 있다.In the specification and claims, D50 may be defined as a particle size based on 50% of a particle size distribution, and may be measured using a laser diffraction method. For example, in the method of measuring the average particle diameter (D50) of the positive active material, the particles of the positive active material are dispersed in a dispersion medium, and then introduced into a commercially available laser diffraction particle size measuring device (eg, Microtrac MT 3000) to about 28 kHz After irradiating the ultrasonic waves with an output of 60 W, the average particle diameter D50 corresponding to 50% of the volume accumulation amount in the measuring device can be calculated.
본 발명에 있어서 '1차 입자'란 주사형 전자 현미경을 이용하여 5000배 내지 20000배의 시야에서 관찰하였을 때 외관상 입계가 존재하지 않는 입자를 의미한다. 본 발명에서 1차 입자는 평균 입경(D50)에 따라 1차 미세(micro) 입자, 1차 거대(macro) 입자로 구분될 수 있다. In the present invention, the term 'primary particles' refers to particles having no apparent grain boundaries when observed in a field of view of 5000 times to 20000 times using a scanning electron microscope. In the present invention, the primary particles may be classified into primary micro particles and primary macro particles according to an average particle diameter (D50).
본 발명에서 '2차 입자'란 상기 1차 입자가 응집되어 형성된 입자이다. 본 발명에서 2차 입자는 평균 입경(D50)에 따라 2차 대입자, 2차 소입자로 구분될 수 있다. In the present invention, 'secondary particles' are particles formed by agglomeration of the primary particles. In the present invention, secondary particles may be classified into secondary large particles and secondary small particles according to an average particle diameter (D50).
한편, 상기 2차 대입자는 2차 입자 대입자로 불리울 수 있다. 여기에서, 2차 입자 대입자는, 1차 미세(micro) 입자가 수십 내지 수백 개 응집되어 형성된 입자이다. 2차 입자 대입자와 대비되는 개념으로 2차 입자 소입자가 존재한다. 여기에서, 2차 입자 소입자는, 1차 미세(micro) 입자가 수십 내지 수백개 응집되어 형성된 입자이다. 2차 입자 대입자의 평균 입경(D50)은 2차 입자 소입자의 평균 입경(D50)에 비하여 크다. Meanwhile, the secondary large particle may be referred to as a secondary large particle. Here, the secondary particle large particle is a particle formed by aggregation of tens to hundreds of primary micro particles. Secondary particles Small particles exist as a concept in contrast to large particles. Here, the secondary particle small particle is a particle formed by aggregation of several tens to hundreds of primary micro particles. The average particle diameter (D50) of the large secondary particles is larger than the average particle diameter (D50) of the small secondary particles.
반면, 본 발명에서 말하는 2차 소입자는 전술한 2차 입자 대입자 및/또는 2차 입자 소입자와는 궤를 달리하는 것이다. 즉, 본 발명의 일 측면에서 말하는 2차 소입자는 바람직하게는 1차 거대(micro) 입자가 10개 내외로 응집되어 형성된 입자이다.On the other hand, the secondary small particle referred to in the present invention is different from the above-described large secondary particle and/or secondary particle small particle. That is, the secondary small particles in one aspect of the present invention are preferably particles formed by aggregation of about 10 primary micro particles.
1차 미세 입자가 응집되어 형성되는 2차 입자 대입자/ 2차 입자 소입자와 1차 거대 입자가 응집되어 형성되는 2차 소입자를 비교할 경우 1차 거대 입자가 응집되어 형성된 2차 입자가 더욱 매끈한 표면을 갖게 된다.Secondary particles formed by agglomeration of primary fine particles Large secondary particles/ When comparing small secondary particles and secondary small particles formed by agglomeration of primary large particles, secondary particles formed by aggregation of primary large particles are more have a smooth surface.
본 발명에서, '단입자'란 상기 2차 입자와는 독립적으로 존재하는 것으로, 외관상에 입계가 존재하지 않는 입자로서, 예를 들어, 입자 지름이 0.5 ㎛ 이상의 입자를 의미한다. In the present invention, 'single particle' is a particle that exists independently of the secondary particles and does not have a grain boundary in appearance, for example, a particle having a particle diameter of 0.5 µm or more.
본 발명에 있어서, '입자'라고 기재하는 경우에는 단입자, 2차 입자, 1차 입자 중 어느 하나 또는 모두가 포함되는 의미일 수 있다. In the present invention, when 'particle' is described, it may mean that any one or all of single particles, secondary particles, and primary particles are included.
양극 활물질cathode active material
리튬 이차 전지에 양극 활물질은, 부피당 에너지 밀도를 향상시키기 위해 입도 분포가 다른 두 종류의 입자를 혼합하여 양극 활물질로 사용하는 경우가 대부분이다. 예를 들어, 대입자 양극 활물질과 소입자 양극 활물질을 적정 비율로 사용하게 되면 바이모달(bimodal) 효과로 인해 동일 압력 조건에서 대/소입자의 밀도값에서 산술적으로 계산한 값 대비 높은 밀도를 나타내게 된다. In most lithium secondary batteries, the cathode active material is used as a cathode active material by mixing two types of particles having different particle size distributions in order to improve energy density per volume. For example, when a large particle positive active material and a small particle positive active material are used in an appropriate ratio, the bimodal effect causes a higher density than the value calculated arithmetically from the density values of large and small particles under the same pressure condition. do.
한편, 양극 활물질 입자를 이용하여 양극을 제조시에는 대부분 압연 공정을 거치게 된다. 이 때, 양극 활물질 입자가 소위 1차 입자가 모여서 형성된 2차 입자인 경우에는, 압연 공정 중에 입자 깨짐이 발생할 수 있다. 깨진 입자는 전기 전도성이 손실되며, 표면적 증가로 인해 전해액과의 부반응을 심화시킬 수 있다. 결과적으로 수명 특성이 열위에 놓이는 문제가 있다. On the other hand, when a positive electrode is manufactured using positive electrode active material particles, most of it undergoes a rolling process. At this time, when the positive electrode active material particles are secondary particles formed by gathering so-called primary particles, particle cracking may occur during the rolling process. Broken particles lose electrical conductivity and may intensify side reactions with the electrolyte due to an increase in surface area. As a result, there is a problem in that the life characteristics are inferior.
본 발명의 일 측면에서는 기존과 다른 2차 입자 형태를 포함하는 양극 활물질을 제공한다. In one aspect of the present invention, there is provided a positive electrode active material including a secondary particle shape different from the conventional one.
구체적으로, Specifically,
대입자의 제1 양극 활물질 및 소입자의 제2 양극 활물질을 포함하는 리튬 이차 전지용 양극 활물질이며, It is a positive electrode active material for a lithium secondary battery comprising a first positive electrode active material of large particles and a second positive electrode active material of small particles,
상기 제1 양극 활물질은, 1차 미세(micro) 입자의 응집체를 포함하는 적어도 하나의 2차 대입자를 포함하며,The first positive active material includes at least one secondary large particle including an aggregate of primary micro particles,
상기 제2 양극 활물질은, 1차 거대(macro) 입자의 응집체를 포함하는 적어도 하나의 2차 소입자를 포함하며, The second positive active material includes at least one secondary small particle including an aggregate of primary macro particles,
상기 1차 거대 입자의 평균 입경(D50)은 1 ㎛ 이상이며,The average particle diameter (D50) of the primary large particles is 1 μm or more,
상기 제1 양극 활물질의 평균 입경(D50)/상기 제2 양극 활물질의 평균 입경(D50)의 비는 2 이상이며, The ratio of the average particle diameter (D50) of the first positive electrode active material / the average particle diameter (D50) of the second positive electrode active material is 2 or more,
상기 제1 양극 활물질과 상기 제2 양극 활물질의 중량비는 50 : 50 내지 70 : 30인 것을 특징으로 하는 양극 활물질인 것이다. The weight ratio of the first positive active material to the second positive active material is a positive active material, characterized in that 50:50 to 70:30.
상기 양극 활물질은, 상기 특징을 가짐으로써, 충방전 용량 유지율이 증가된 니켈계 양극 활물질을 제공할 수 있다. 또한, 압연시 미분 생성 비율이 감소된 양극 활물질을 제공할 수 있다. The positive active material may provide a nickel-based positive active material having an increased charge/discharge capacity retention rate by having the above characteristics. In addition, it is possible to provide a positive electrode active material having a reduced rate of generation of fine powder during rolling.
이하, 상기 제1 및 제2 입자가 가지는 상기 특성을 상세히 설명한다. Hereinafter, the characteristics of the first and second particles will be described in detail.
1차 거대 입자가 응집된 2차 소입자 및 상기 2차 소입자를 포함하는 소입자 제2 양극 활물질Secondary small particles in which the primary large particles are aggregated and small particles comprising the secondary small particles Second positive active material
본 발명의 일 측면에서는 전술한 문제를 해결하기 위하여 1차 거대 입자가 응집된 2차 입자를 포함하는 것이다. 기존의 2차 입자는 1차 미세 입자가 수십 내지 수백개 응집되어 2차 입자를 형성한다. 반면, 본 발명의 일 측면에서는 1차 입자의 평균 입경(D50)이 1 ㎛ 이상인 1차 거대 입자가 바람직하게는 1 내지 10개 이내로 응집되어 “2차 소입자”를 구성한다. In one aspect of the present invention, in order to solve the above-described problem, the primary large particles include secondary particles agglomerated. In the existing secondary particles, tens to hundreds of primary fine particles are aggregated to form secondary particles. On the other hand, in one aspect of the present invention, the primary large particles having an average particle diameter (D50) of 1 μm or more are preferably aggregated within 1 to 10 to constitute “secondary small particles”.
본 발명자들은, 기존의 2차 입자 대입자와 2차 입자 소입자를 혼합하는 경우에는 압연 과정에서 2차 입자의 깨짐이 발생하고 전기화학 특성이 열위에 놓이는 문제가 있음을 발견하였다. 이 때 기존의 2차 입자 대입자와 2차 입자 소입자란, 1차 미세 입자가 수십 내지 수백개 응집되어 형성된 2차 입자이되, 평균 직경(D50)이 큰 경우를 “2차 입자 대입자”, 평균 직경(D50)이 작은 경우를 “2차 입자 소입자”라고 지칭한다. The present inventors have discovered that, in the case of mixing the existing large secondary particles and small secondary particles, cracking of the secondary particles occurs during the rolling process and there is a problem in that the electrochemical properties are inferior. At this time, the existing large secondary particles and small secondary particles are secondary particles formed by aggregation of tens to hundreds of primary fine particles, but with a large average diameter (D50), “large secondary particles” , the case where the average diameter (D50) is small is referred to as “small secondary particles”.
반면, 본 발명의 일 측면에서는 “1차 거대 입자가 응집된 2차 소입자”를 기존의 “2차 입자 대입자”와 적정 비율로 혼합함에 따라, 압연과정에서의 깨짐을 억제할 수 있다. 이는, 본 발명에 따른 2차 소입자를 기존의 2차 대입자에 혼합하는 경우, 2차 소입자의 압연 밀도(press density)가 상대적으로 높아 혼합 양극 활물질 전체에 대하여 동일 압연 밀도에서 2차 대입자에 가해지는 스트레스가 감소되기 때문인 것으로 보인다. 또한, 기존의 2차 입자 소입자에 비해 본 발명에 따른 2차 소입자의 표면이 매끄러워 2차 대입자와 혼합시 바이모달 효과를 효과적으로 나타내는 것으로 보인다. On the other hand, in one aspect of the present invention, by mixing the “secondary small particles in which the primary large particles are aggregated” with the existing “large secondary particles” in an appropriate ratio, cracking in the rolling process can be suppressed. This is because, when the secondary small particles according to the present invention are mixed with the existing secondary large particles, the press density of the secondary small particles is relatively high, so that the secondary large particles at the same rolling density for the entire mixed positive electrode active material. This appears to be due to the reduced stress on the particles. In addition, the surface of the secondary small particle according to the present invention is smoother than the conventional secondary particle small particle, and thus it seems to effectively exhibit a bimodal effect when mixed with the secondary large particle.
본 발명에서 '1차 거대 입자'란 평균 직경(D50)이 1 ㎛ 이상인 것이다. In the present invention, 'primary large particles' means those having an average diameter (D50) of 1 µm or more.
본 발명의 구체적인 일 실시양태에 있어서, 상기 1차 거대 입자의 평균 입경은 1 ㎛ 이상, 1.5 ㎛ 이상, 2 ㎛ 이상, 2.5 ㎛ 이상, 3 ㎛ 이상, 또는 3.5 ㎛ 이상일 수 있으며, 5 ㎛ 이하, 4.5 ㎛ 이하, 또는 4 ㎛ 이하일 수 있다. 상기 1차 거대 입자의 평균 입경이 1 ㎛ 미만인 경우, 이를 응집한 2차 입자는 종래의 2차 소입자에 해당되어 압연시 입자 깨짐이 발생하는 문제가 있을 수 있다. In a specific embodiment of the present invention, the average particle diameter of the primary large particles may be 1 μm or more, 1.5 μm or more, 2 μm or more, 2.5 μm or more, 3 μm or more, or 3.5 μm or more, and 5 μm or less; It may be 4.5 μm or less, or 4 μm or less. When the average particle diameter of the primary large particles is less than 1 μm, the agglomerated secondary particles correspond to conventional secondary small particles, and thus there may be a problem in that particles are broken during rolling.
본 발명에서 '1차 거대 입자'는 평균 입경(D50)/ 평균 결정 크기(crystal size)의 비가 3 이상인 것을 의미하는 것이다. 즉, 상기 1차 거대 입자는 종래 2차 입자를 구성하는 1차 미세(micro) 입자와 비교할 때, 1차 입자의 평균 입경과 평균 결정 크기가 동시에 성장한 것이다. In the present invention, 'primary large particles' means a ratio of average particle diameter (D50)/average crystal size of 3 or more. That is, the primary large particles have an average particle diameter and an average crystal size of the primary particles grown at the same time as compared to the primary micro particles constituting the conventional secondary particles.
크랙(crack) 관점에서 보자면 기존의 단입자와 같이 외관상 입계가 존재하지 존재하지 않으면서도 평균 입경이 큰 것이 유리하다. 하지만 기존의 단입자는 기존의 2차 입자 형태의 입자와 혼합되어 사용되는 경우, 압연시 2차 입자 형태의 양극 활물질이 먼저 깨져버리게 되는 문제가 발생할 수 있다. 또한 외관상 입계가 존재하지 않으면서도 평균 입경이 큰 형태로 만들기 위하여 기존 2차 입자 형태의 조건보다 소성 온도를 높이게 되고, 이때 입자의 표면에 rock salt 가 형성되어 표면 저항이 높아지는 문제가 있는 것을 발견하였다. 이 두 가지 문제를 해결하기 위해서 기존 단입자 소성 조건 보다 조금 낮은 온도에서 소성하여 1차 거대 입자가 응집된 2차 입자 형태의 양극 활물질을 개발하였다. From the point of view of cracks, it is advantageous that grain boundaries exist and do not exist, but have a large average particle diameter like the conventional single particles. However, when the existing single particles are mixed with the existing secondary particle type particles and used, there may be a problem in that the secondary particle type cathode active material is broken first during rolling. In addition, it was found that the calcination temperature was higher than that of the existing secondary particle type to make it into a shape with a large average particle diameter without apparent grain boundaries, and at this time, rock salt was formed on the surface of the particle, resulting in increased surface resistance. . To solve these two problems, a cathode active material in the form of secondary particles in which primary large particles are agglomerated by firing at a temperature slightly lower than the conventional single particle firing conditions was developed.
즉, 본 발명에서의 1차 거대 입자는, 기존 2차 입자 형태의 양극 활물질과 비교할 때 평균 입경뿐만 아니라 평균 결정 크기도 크며, 외관상의 입계가 존재하지 않는 입자를 의미하는 것이다. That is, in the present invention, the primary large particles refer to particles having a larger average crystal size as well as an average particle diameter as compared to a positive electrode active material in the form of a conventional secondary particle, and having no apparent grain boundaries.
이와 같이, 기존 단입자 소성 조건보다 조금 낮은 온도에서 소성하여 1차 거대 입자가 응집된 2차 입자 형태의 양극 활물질을 제조하는 경우, 고온에서의 소성으로 인해 표면에 rock salt가 생겨 저항 증가가 큰 기존의 단입자에 비해, 표면 저항이 낮아지며 장수명 측면에서도 유리하다. As such, in the case of producing a cathode active material in the form of secondary particles in which primary large particles are aggregated by sintering at a temperature slightly lower than the existing single-particle sintering conditions, rock salt is formed on the surface due to sintering at high temperature, resulting in a large increase in resistance. Compared to the conventional single particles, the surface resistance is lowered and it is advantageous in terms of long life.
이 때, 상기 1차 거대 입자의 평균 결정 크기(crystal size)는 Cu Kα X선(X-ray)에 의한 X선 회절 분석(XRD)을 이용하여 정량적으로 분석될 수 있다. 구체적으로는 제조된 입자를 홀더에 넣어 X선을 상기 입자에 조사해 나오는 회절 격자를 분석함으로써, 1차 거대 입자의 평균 결정 크기를 정량적으로 분석할 수 있다. 예를 들어, 전술한 방법에 의해 분석할 수 있다. In this case, the average crystal size of the primary large particles may be quantitatively analyzed using X-ray diffraction analysis (XRD) by Cu Kα X-rays. Specifically, the average crystal size of the primary large particles can be quantitatively analyzed by putting the prepared particles in a holder and analyzing the diffraction grating that irradiates the particles with X-rays. For example, it can be analyzed by the method described above.
본 발명의 구체적인 일 실시양태에 있어서, 상기 평균 입경(D50)/ 평균 결정 크기(crystal size)의 비는 2 이상, 2.5 이상, 3 이상일 수 있으며, 50 이하, 40 이하, 35 이하일 수 있다. In a specific embodiment of the present invention, the ratio of the average particle size (D50) / average crystal size (crystal size) may be 2 or more, 2.5 or more, 3 or more, and 50 or less, 40 or less, 35 or less.
또한, 상기 1차 거대 입자의 평균 결정 크기는, 150 nm 이상, 170 nm 이상, 200 nm 이상일 수 있으며, 300nm 이하, 270nm 이하, 또는 250nm 이하일 수 있다. In addition, the average crystal size of the primary large particles may be 150 nm or more, 170 nm or more, 200 nm or more, and 300 nm or less, 270 nm or less, or 250 nm or less.
한편, 본 발명에서 “2차 소입자”란, 전술한 1차 거대 입자가 응집된 형태이다. 상기 2차 소입자는, 기존의 단입자 수득방법과 다음과 같은 점에서 차이가 있다. Meanwhile, in the present invention, the term “secondary small particles” refers to an aggregated form of the above-described primary large particles. The secondary small particles are different from the conventional method for obtaining single particles in the following points.
기존의 단입자는, 기존의 2차 입자용 전구체를 그대로 사용하여 1차 소성 온도만 높여 단입자를 형성하였다. 반면, 본 발명의 일 측면에 따른 2차 소입자는, 기공도가 높은 별개의 전구체를 사용하는 것이다. 이에 따라, 소성 온도를 높이 올리지 않아도 입경 크기가 큰 1차 거대 입자가 성장될 수 있으며, 반면 2차 소입자의 평균 직경은 기존에 비해 상대적으로 덜 성장할 수 있다. As for the existing single particles, single particles were formed by increasing only the primary firing temperature by using the existing precursor for secondary particles as it is. On the other hand, the secondary small particles according to an aspect of the present invention use a separate precursor having a high porosity. Accordingly, the primary large particles having a large particle size may be grown without raising the firing temperature, while the average diameter of the secondary small particles may be relatively small compared to the conventional ones.
이에 따라, 본 발명의 일 측면에 따른 2차 소입자는, 기존 2차 입자와 동일 또는 유사한 평균 입경(D50)을 가지면서도 1차 입자의 평균 직경(D50)이 큰 형태인 것이다. 즉, 기존에 양극 활물질이 갖는 일반적인 형태 즉 평균 입경이 작은 1차 입자들이 모여서 2차 입자를 형성하는 형태와 다르게, 1차 입자의 크기를 키운 1차 거대 입자가 응집한 2차 입자 형태를 제공한다. Accordingly, the secondary small particles according to an aspect of the present invention have the same or similar average particle diameter (D50) as the existing secondary particles and have a large average diameter (D50) of the primary particles. In other words, unlike the conventional positive electrode active material, in which primary particles with small average particle diameters gather to form secondary particles, it provides a secondary particle form in which primary large particles with increased primary particle size are aggregated. do.
본 발명의 구체적인 일 실시양태에 있어서, 상기 2차 소입자는 상기 1차 거대 입자가 1개 내지 10개 이내로 응집된 것일 수 있다. 보다 구체적으로, 상기 2차 소입자는 상기 1차 거대 입자가 1개 이상, 2개 이상, 3개 이상, 또는 4개 이상 응집된 것일 수 있으며, 상기 수치 범위 내에서 상기 1차 거대 입자가 10개 이하, 9개 이하, 8개 이하, 또는 7개 이하로 응집된 것일 수 있다. In a specific embodiment of the present invention, the secondary small particles may be agglomerated 1 to 10 or less of the primary large particles. More specifically, the secondary small particles may be one or more, two or more, three or more, or four or more aggregates of the primary large particles, and within the numerical range, the primary large particles are 10 It may be an aggregate of no more than 9 pieces, no more than 8 pieces, or no more than 7 pieces.
본 발명에서, 상기 2차 소입자는, 기존과 동일 또는 유사한 평균 입경(D50)을 가지면서도 1차 거대 입자의 평균 직경(D50)이 큰 형태인 것이다. 즉, 기존에 양극 활물질이 갖는 일반적인 형태 즉 평균 입경이 작은 1차 미세 입자들이 모여서 2차 입자를 형성하는 형태와 다르게, 1차 입자의 크기를 키운 1차 거대 입자가 응집한 2차 입자 형태를 제공한다. In the present invention, the secondary small particles have a large average diameter (D50) of the primary large particles while having the same or similar average particle diameter (D50) as before. In other words, unlike the conventional positive electrode active material, in which primary fine particles with small average particle diameters gather to form secondary particles, the secondary particle form in which primary large particles of increased primary particle size are aggregated to provide.
본 발명의 일 측면에 따른 2차 소입자는 평균 직경(D50)이 3 ㎛ 내지 6 ㎛인 것이다. 보다 구체적으로, 3 ㎛ 이상, 3.5 ㎛ 이상, 4 ㎛ 이상, 또는 4.5 ㎛ 이상인 것이며, 6 ㎛ 이하, 5.5 ㎛ 이하, 또는 5 ㎛ 이하인 것이다. The secondary small particles according to an aspect of the present invention have an average diameter (D50) of 3 μm to 6 μm. More specifically, it is 3 µm or more, 3.5 µm or more, 4 µm or more, or 4.5 µm or more, and is 6 µm or less, 5.5 µm or less, or 5 µm or less.
일반적으로 입자 형태를 막론하고, 동일한 조성일 때, 소성 온도가 증가할수록 입자의 크기 및 입자 내 평균 결정 크기는 증가한다. 반면, 본 발명의 일 측면에 따른 2차 소입자는, 다공성의 전구체를 이용하여, 종래에 비해 소성 온도를 높이 올리지 않아도 입경 크기가 큰 1차 거대 입자가 성장될 수 있으며, 반면 2차 소입자는 기존에 비해 상대적으로 덜 성장할 수 있다. In general, regardless of particle shape, when the composition is the same, the size of the particles and the average crystal size within the particles increase as the firing temperature increases. On the other hand, in the secondary small particles according to an aspect of the present invention, by using a porous precursor, primary large particles having a large particle size can be grown without raising the sintering temperature higher than in the prior art, whereas the secondary small particles can grow relatively less than before.
이에 따라, 본 발명의 일 측면에 따른 2차 소입자는 종래 2차 입자와 평균 직경(D50)이 동일 또는 유사하면서, 종래 1차 미세 입자에 비해 평균 직경 및 평균 결정 크기가 큰 1차 거대 입자로 이루어져 있다. Accordingly, the secondary small particles according to one aspect of the present invention have the same or similar average diameter (D50) to the conventional secondary particles, and have larger average diameter and average crystal size than the conventional primary fine particles. consists of
본 발명의 구체적인 일 실시양태에 있어서, 상기 2차 소입자의 평균 입경(D50)/상기 1차 거대 입자의 평균 입경(D50)의 비는 2 내지 4배일 수 있다. In a specific embodiment of the present invention, the ratio of the average particle diameter (D50) of the secondary small particles to the average particle diameter (D50) of the primary large particles may be 2 to 4 times.
본 발명에서, 소입자의 제2 양극 활물질은 전술한 2차 소입자를 포함하는 것을 의미한다. 이 때, 상기 제2 양극 활물질은, 상기 2차 소입자를 압연시 상기 1차 거대 입자가 떨어져 나가며, 상기 1차 거대 입자 자체는 깨지지 않는 것일 수 있다. 이 때, 상기 압연 조건은 양극 활물질을 전극으로 제작하여 기공도 15~30% 수준으로 압연하는 조건일 수 있다. 예를 들어, 상기 압연 조건은 9 ton 이상의 압력을 가하는 것일 수 있다. 보다 구체적으로, 9 ton 을 가압하는 것일 수 있다.In the present invention, the second positive electrode active material of small particles means including the above-described secondary small particles. In this case, the second positive active material may be one in which the primary large particles fall off when the secondary small particles are rolled, and the primary large particles themselves are not broken. In this case, the rolling condition may be a condition in which the positive electrode active material is manufactured as an electrode and rolled to a level of 15 to 30% porosity. For example, the rolling condition may be to apply a pressure of 9 tons or more. More specifically, it may be to press 9 ton.
이에 따라, 본 발명의 일 측면에 따른 양극 활물질은, 전극으로 제작하여 기공도 15~30% 수준으로 압연시 1㎛ 이하의 미분 입자가 10% 미만인 것이다. Accordingly, in the positive electrode active material according to an aspect of the present invention, when the cathode active material is manufactured as an electrode and rolled to a level of 15 to 30% porosity, less than 10% of fine particles of 1 μm or less are present.
또한, 본 발명의 일 측면에 따른 양극 활물질은 전극으로 제작하여 기공도 15~30% 수준으로 압연시 2차 대입자의 최대 피크 강도 감소율이 2% 미만인 것이다. In addition, the cathode active material according to an aspect of the present invention is produced as an electrode and the maximum peak intensity reduction rate of the secondary large particles is less than 2% when rolled to a porosity level of 15 to 30%.
1차 미세 입자가 응집된 2차 대입자 및 상기 2차 대입자를 포함하는 대입자 제1 양극 활물질Secondary large particles in which primary fine particles are aggregated and large-particle first positive electrode active material comprising the secondary large particles
본 발명의 일 측면에서는 전술한 2차 소입자 이외에 2차 대입자를 추가적으로 더 포함한다. In one aspect of the present invention, it further includes a secondary large particle in addition to the secondary small particle described above.
이 때, 2차 대입자는 1차 미세 입자가 응집된 형태이다. 예를 들어, 상기 1차 미세 입자가 수십 내지 수백개 응집된 형태일 수 있다. 환언하면, 본 발명에서 "2차 대입자"는 전술한 "2차 입자 대입자"와 동일한 개념이다.In this case, the secondary large particles are in the form of agglomerated primary fine particles. For example, the primary fine particles may be in the form of agglomerated tens to hundreds. In other words, in the present invention, the "secondary large particle" is the same concept as the above-mentioned "secondary large particle".
본 발명의 구체적인 일 실시양태에 있어서, 상기 2차 대입자의 평균 직경(D50)은, 10 ㎛ 내지 20 ㎛인 것이다. 2차 대입자의 평균 직경(D50)이 10 ㎛ 미만일 경우 2차 대입자의 입자 깨짐 현상이 증대될 수 있다. 보다 구체적으로, 10 ㎛ 이상, 12 ㎛ 이상, 또는 14 ㎛ 이상인 것이며, 20 ㎛ 이하, 18 ㎛ 이하, 또는 16 ㎛ 이하인 것이다. In a specific embodiment of the present invention, the average diameter (D50) of the secondary large particles is 10 μm to 20 μm. When the average diameter (D50) of the secondary large particles is less than 10 μm, the particle breakage of the secondary large particles may be increased. More specifically, it is 10 μm or more, 12 μm or more, or 14 μm or more, and is 20 μm or less, 18 μm or less, or 16 μm or less.
본 발명의 구체적인 일 실시양태에 있어서, 상기 1차 미세 입자의 평균 입경(D50)은 0.1 ㎛ 내지 0.5 ㎛인 것이다. 보다 구체적으로, 0.1 ㎛ 이상, 0.2 ㎛ 이상, 또는 0.3 ㎛ 이상일 수 있으며, 0.5 ㎛ 이하, 또는 0.4 ㎛ 이하일 수 있다. In a specific embodiment of the present invention, the average particle diameter (D50) of the primary fine particles is 0.1 μm to 0.5 μm. More specifically, it may be 0.1 μm or more, 0.2 μm or more, or 0.3 μm or more, and may be 0.5 μm or less, or 0.4 μm or less.
함량 및 비율content and proportion
본 발명의 일 측면에 따른 양극 활물질에 있어서, 상기 제1 양극 활물질의 평균 입경(D50)/상기 제2 양극 활물질의 평균 입경(D50)의 비는 2 이상이며, 상기 제1 양극 활물질과 상기 제2 양극 활물질의 중량비는 50 : 50 내지 70 : 30인 것이다. In the positive active material according to an aspect of the present invention, the ratio of the average particle diameter (D50) of the first positive active material / the average particle diameter (D50) of the second positive active material is 2 or more, and the first positive active material and the first positive active material 2 The weight ratio of the positive active material is 50:50 to 70:30.
보다 구체적으로, 상기 제1 양극 활물질과 상기 제2 양극 활물질의 중량비는 50 : 50 내지 70 : 30, 예를 들어, 55 : 45 또는 60 : 40, 또는 65 : 35일 수 있다. More specifically, A weight ratio of the first positive active material to the second positive active material may be 50:50 to 70:30, for example, 55:45 or 60:40, or 65:35.
상기 제1 양극 활물질만을 단독으로 사용하거나 상기 제2 양극 활물질만을 단독으로 사용하는 경우에는 압연시 형성되는 미분 양이 본 발명의 양극 활물질에 비해 상대적으로 많이 존재한다. When only the first positive active material is used alone or when only the second positive active material is used alone, the amount of fine powder formed during rolling is relatively larger than that of the positive active material of the present invention.
또한, 종래와 같이 기존 2차 입자 대입자와 1차 미세 입자로 구성된 2차 입자 소입자를 사용하는 경우에는 상기 2차 입자 대입자를 단독으로 사용할 때에 비해 미분 양이 상대적으로 줄어들 수 있으나, 여전히 입자 깨짐이 발생하고 용량 유지율이 낮게 나타난다. In addition, in the case of using small secondary particles composed of the existing large secondary particles and primary fine particles as in the prior art, the amount of unsold may be relatively reduced compared to when the secondary large particles are used alone, but still particles Cracking occurs and capacity retention is low.
반면, 놀랍게도 2차 대입자와 2차 소입자를 동시에 사용하는 경우, 즉, 기존의 2차 입자 소입자를 전술한 2차 소입자로 치환한 경우에는, 미분 영역의 피크가 줄어들고, 2차 대입자의 피크 강도 변화가 줄어드는 것을 발견하였다. 이에 따라, 압연시 2차 대입자의 형상이 압연 전과 비교했을 때 기준으로 잘 유지되며, 미분 형성도 억제되는 것을 확인하였다. On the other hand, surprisingly, when the secondary large particle and the secondary small particle are used at the same time, that is, when the existing secondary small particle is replaced with the above-mentioned secondary small particle, the peak of the differential region is reduced, and the secondary substitution It was found that the change in the peak intensity of the ruler was reduced. Accordingly, it was confirmed that the shape of the secondary large particles during rolling was well maintained as a reference compared to before rolling, and the formation of fine powder was also suppressed.
또한, 본 발명의 일 측면에서는, 기존 2차 입자 대입자와 2차 입자 소입자를 혼합한 조성이나, 또는, 2차 소입자를 단독 사용한 조성에 비하여, 수명 특성이 크게 향상됨을 확인하였다. In addition, in one aspect of the present invention, it was confirmed that the lifespan characteristics were significantly improved compared to a composition in which the existing large secondary particles and small secondary particles were mixed, or a composition in which the secondary small particles were used alone.
다만, 이러한 특성은, 단순히 2차 대입자와 2차 소입자를 혼합하는 경우에는 달성되지 않으며, 전술한 바와 같이, 상기 제1 양극 활물질의 평균 입경(D50)/상기 제2 양극 활물질의 평균 입경(D50)의 비는 2 이상이어야 한다. However, this characteristic is not achieved when simply mixing the secondary large particles and the secondary small particles, and as described above, the average particle diameter (D50) of the first positive active material / the average particle diameter of the second positive active material The ratio of (D50) should not be less than 2.
본 발명의 구체적인 일 실시양태에 있어서, 상기 제1 양극 활물질의 평균 입경(D50)/상기 제2 양극 활물질의 평균 입경(D50)의 비는 2 이상, 3 이상, 또는 3.5 이상일 수 있다. In a specific embodiment of the present invention, the ratio of the average particle diameter (D50) of the first positive active material to the average particle diameter (D50) of the second positive active material may be 2 or more, 3 or more, or 3.5 or more.
조성Furtherance
상기 2차 대입자 및/또는 2차 소입자는, 니켈계 리튬 전이금속 산화물을 포함하는 것이다. The secondary large particles and/or secondary small particles include nickel-based lithium transition metal oxide.
이 때, 상기 니켈계 리튬 전이금속 산화물은, Li(1+a)Ni(1-(a+x+y+w))CoxM1yM2wO2 (여기에서, 0≤a≤0.5, 0≤x≤0.35, 0≤y≤0.35, 0≤w≤0.1, 0≤a+x+y+w≤0.7, M1은 Mn 및 Al으로 이루어지는 군으로부터 선택되는 적어도 1종, M2는 Ba, Ca, Zr, Ti, Mg, Ta, Nb 및 Mo으로 이루어지는 군으로부터 선택되는 적어도 1종)을 포함할 수 있다. At this time, the nickel-based lithium transition metal oxide is, Li (1+a) Ni (1-(a+x+y+w)) Co x M1 y M2 w O 2 (here, 0≤a≤0.5, 0≤x≤0.35, 0≤y≤0.35, 0≤w≤0.1, 0≤a+x+y+w≤0.7, M1 is at least one selected from the group consisting of Mn and Al, M2 is Ba, Ca , Zr, Ti, Mg, Ta, at least one selected from the group consisting of Nb and Mo) may include.
상기 식에서, a, x, y, 및 w는 니켈계 리튬 전이금속 산화물 내 각 원소의 몰비를 나타낸다. In the above formula, a, x, y, and w represent the molar ratio of each element in the nickel-based lithium transition metal oxide.
이 때, 상기 2차 입자의 결정 격자 내 도핑된 금속 M1과 M2는 원소 M1 및/또는 원소 M2의 위치 선호도에 따라 입자의 일부 표면에만 위치할 수도 있고, 입자 표면에서부터 입자 중심 방향으로 감소하는 농도구배를 가지며 위치할 수 있으며, 또는 입자 전체에 걸쳐 균일하게 존재할 수도 있다. At this time, the doped metals M1 and M2 in the crystal lattice of the secondary particles may be located only on a part of the surface of the particle according to the position preference of the element M1 and/or the element M2, and the concentration decreases from the particle surface to the particle center It may be positioned with a gradient, or it may be uniformly present throughout the particle.
상기 2차 입자는 금속 M1과 M2에 의해 도핑, 또는 코팅 및 도핑될 경우, 특히 표면구조의 안정화로 활물질이 장수명 특성이 보다 개선될 수 있다. When the secondary particles are doped or coated and doped with metals M1 and M2, in particular, the long life characteristics of the active material may be further improved by stabilizing the surface structure.
양극 활물질 제조방법Method for manufacturing cathode active material
본 발명의 일 측면에 따른 양극 활물질은 다음과 같은 방법으로 제조될 수 있다. 다만, 이에 제한되는 것은 아니다. The positive active material according to an aspect of the present invention may be manufactured by the following method. However, the present invention is not limited thereto.
구체적으로, 제1 양극 활물질과 제2 양극 활물질을 각각 제조한 후 혼합하여 형성할 수 있다. Specifically, it may be formed by preparing the first positive active material and the second positive active material, respectively, and then mixing.
예를 들어, 제1 양극 활물질과 제2 양극 활물질은 다음과 같은 방법으로 제조될 수 있다. For example, the first positive active material and the second positive active material may be manufactured by the following method.
구체적으로, 니켈(Ni), 코발트(Co) 및 망간(Mn)을 포함하는 양극 활물질 전구체와, 리튬 원료 물질을 혼합하고 1차 소성하는 단계; 및 상기 1차 소성 후 리튬 원료 물질을 혼합하여 2차 소성하는 단계;를 포함할 수 있다. Specifically, the method comprising: mixing a cathode active material precursor including nickel (Ni), cobalt (Co) and manganese (Mn) and a lithium raw material and performing primary firing; and mixing the lithium raw material after the primary firing and performing secondary firing.
상기 1차 소성 및 상기 2차 소성을 통해, 1차 입자를 포함하는 2차 입자를 제조할 수 있다. Through the primary and secondary firing, secondary particles including primary particles may be manufactured.
상기 양극 활물질의 제조방법을 단계별로 추가 설명한다. A method of manufacturing the positive active material will be further described step by step.
먼저, 니켈(Ni), 코발트(Co) 및 망간(Mn)을 포함하는 양극 활물질 전구체를 마련한다. First, a cathode active material precursor including nickel (Ni), cobalt (Co), and manganese (Mn) is prepared.
이 때, 대입자의 제1 양극 활물질 제조를 위한 전구체는 시판되는 양극 활물질 전구체를 구입하여 사용하거나, 당해 기술 분야에서 잘 알려진 양극 활물질 전구체의 제조방법에 따라 제조될 수 있다. At this time, the precursor for preparing the first positive electrode active material of large particles may be prepared by purchasing a commercially available positive electrode active material precursor or according to a method for preparing a positive electrode active material precursor well known in the art.
예를 들면, 상기 전구체는 니켈 함유 원료물질, 코발트 함유 원료물질 및 망간 함유 원료물질을 포함하는 전이 금속 용액에 암모늄 양이온 함유 착물 형성제와 염기성 화합물을 첨가하여 공침 반응시켜 제조되는 것일 수 있다.For example, the precursor may be prepared by adding an ammonium cation-containing complexing agent and a basic compound to a transition metal solution including a nickel-containing raw material, a cobalt-containing raw material, and a manganese-containing raw material, followed by a co-precipitation reaction.
상기 니켈 함유 원료물질은 예를 들면, 니켈 함유 아세트산염, 질산염, 황산염, 할라이드, 황화물, 수산화물, 산화물 또는 옥시수산화물 등일 수 있으며, 구체적으로는, Ni(OH)2, NiO, NiOOH, NiCO3ㆍ2Ni(OH)2ㆍ4H2O, NiC2O2ㆍ2H2O, Ni(NO3)2ㆍ6H2O, NiSO4, NiSO4ㆍ6H2O, 지방산 니켈염, 니켈 할로겐화물 또는 이들의 조합일 수 있으나, 이에 한정되는 것은 아니다.The nickel-containing raw material may be, for example, nickel-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide or oxyhydroxide, specifically, Ni(OH) 2 , NiO, NiOOH, NiCO 3 ㆍ 2Ni(OH) 2 ㆍ4H 2 O, NiC 2 O 2 ㆍ2H 2 O, Ni(NO 3 ) 2 ㆍ6H 2 O, NiSO 4 , NiSO 4 ㆍ6H 2 O, fatty acid nickel salt, nickel halide or these It may be a combination, but is not limited thereto.
상기 코발트 함유 원료 물질은 코발트 함유 아세트산염, 질산염, 황산염, 할라이드, 황화물, 수산화물, 산화물 또는 옥시수산화물 등일 수 있으며, 구체적으로는 Co(OH)2, CoOOH, Co(OCOCH3)2ㆍ4H2O, Co(NO3)2ㆍ6H2O, CoSO4, Co(SO4)2ㆍ7H2O 또는 이들의 조합일 수 있으나, 이에 한정되는 것은 아니다.The cobalt-containing raw material may be cobalt-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide or oxyhydroxide, and specifically, Co(OH) 2 , CoOOH, Co(OCOCH 3 ) 2 ∙ 4H 2 O , Co(NO 3 ) 2 ㆍ6H 2 O, CoSO 4 , Co(SO 4 ) 2 ㆍ7H 2 O, or a combination thereof, but is not limited thereto.
상기 망간 함유 원료물질은 예를 들면, 망간 함유 아세트산염, 질산염, 황산염, 할라이드, 황화물, 수산화물, 산화물, 옥시수산화물 또는 이들의 조합일 수 있으며, 구체적으로는 Mn2O3, MnO2, Mn3O4 등과 같은 망간산화물; MnCO3, Mn(NO3)2, MnSO4, 아세트산 망간, 디카르복실산 망간염, 시트르산 망간, 지방산 망간염과 같은 망간염; 옥시 수산화망간, 염화 망간 또는 이들의 조합일 수 있으나, 이에 한정되는 것은 아니다.The manganese-containing raw material may be, for example, manganese-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, oxyhydroxide, or a combination thereof, specifically Mn 2 O 3 , MnO 2 , Mn 3 manganese oxides such as O 4 ; manganese salts such as MnCO 3 , Mn(NO 3 ) 2 , MnSO 4 , manganese acetate, dicarboxylic acid manganese salt, manganese citrate, fatty acid manganese salt; It may be manganese oxyhydroxide, manganese chloride, or a combination thereof, but is not limited thereto.
상기 전이금속 용액은 니켈 함유 원료물질, 코발트 함유 원료물질 및 망간 함유 원료물질을 용매, 구체적으로는 물, 또는 물과 균일하게 혼합될 수 있는 유기 용매(예를 들면, 알코올 등)의 혼합 용매에 첨가하여 제조되거나, 또는 니켈 함유 원료물질의 수용액, 코발트 함유 원료물질의 수용액 및 망간 함유 원료물질을 혼합하여 제조된 것일 수 있다.The transition metal solution is prepared by mixing a nickel-containing raw material, a cobalt-containing raw material, and a manganese-containing raw material in a solvent, specifically water, or a mixed solvent of an organic solvent that can be uniformly mixed with water (eg, alcohol). It may be prepared by adding, or may be prepared by mixing an aqueous solution of a nickel-containing raw material, an aqueous solution of a cobalt-containing raw material, and a manganese-containing raw material.
상기 암모늄 양이온 함유 착물 형성제는, 예를 들면 NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, NH4CO3 또는 이들의 조합일 수 있으나, 이에 한정되는 것은 아니다. 한편, 상기 암모늄 양이온 함유 착물 형성제는 수용액의 형태로 사용될 수도 있으며, 이때 용매로는 물, 또는 물과 균일하게 혼합 가능한 유기용매(구체적으로, 알코올 등)와 물의 혼합물이 사용될 수 있다.The ammonium cation-containing complexing agent may be, for example, NH 4 OH, (NH 4 ) 2 SO 4 , NH 4 NO 3 , NH 4 Cl, CH 3 COONH 4 , NH 4 CO 3 or a combination thereof, However, the present invention is not limited thereto. On the other hand, the ammonium cation-containing complexing agent may be used in the form of an aqueous solution, and as the solvent, water or a mixture of water and an organic solvent that is uniformly miscible with water (specifically, alcohol, etc.) and water may be used.
상기 염기성 화합물은 NaOH, KOH 또는 Ca(OH)2 등과 같은 알칼리 금속 또는 알칼리 토금속의 수산화물, 이들의 수화물 또는 이들의 조합일 수 있다. 상기 염기성 화합물 역시 수용액의 형태로 사용될 수도 있으며, 이때 용매로는 물, 또는 물과 균일하게 혼합가능한 유기용매(구체적으로, 알코올 등)와 물의 혼합물이 사용될 수 있다.The basic compound may be a hydroxide of an alkali metal or alkaline earth metal such as NaOH, KOH or Ca(OH) 2 , a hydrate thereof, or a combination thereof. The basic compound may also be used in the form of an aqueous solution, and as the solvent, water or a mixture of water and an organic solvent that is uniformly miscible with water (specifically, alcohol, etc.) and water may be used.
상기 염기성 화합물은 반응 용액의 pH를 조절하기 위해 첨가되는 것으로, 금속 용액의 pH가 11 내지 13이 되는양으로 첨가될 수 있다.The basic compound is added to adjust the pH of the reaction solution, and may be added in an amount such that the pH of the metal solution is 11 to 13.
한편, 상기 공침 반응은 질소 또는 아르곤 등의 비활성 분위기하에서, 40℃내지 70℃의 온도에서 수행될 수 있다.Meanwhile, the co-precipitation reaction may be performed at a temperature of 40° C. to 70° C. under an inert atmosphere such as nitrogen or argon.
상기와 같은 공정에 의해 니켈-코발트-망간 수산화물의 입자가 생성되고, 반응 용액 내에 침전된다. 니켈 함유원료물질, 코발트 함유 원료물질 및 망간 함유 원료물질의 농도를 조절하여, 금속 전체 함량 중 니켈(Ni)의 함량이 60몰% 이상인 전구체를 제조할 수 있다. 침전된 니켈-코발트-망간 수산화물 입자를 통상의 방법에 따라 분리시키고, 건조시켜 니켈-코발트-망간 전구체를 얻을 수 있다. 상기 전구체는 1차 입자가 응집되어 형성된 2차 입자일 수 있다.By the above process, particles of nickel-cobalt-manganese hydroxide are generated and precipitated in the reaction solution. By controlling the concentrations of the nickel-containing raw material, the cobalt-containing raw material, and the manganese-containing raw material, it is possible to prepare a precursor having a nickel (Ni) content of 60 mol% or more in the total content of the metal. The precipitated nickel-cobalt-manganese hydroxide particles may be separated according to a conventional method and dried to obtain a nickel-cobalt-manganese precursor. The precursor may be secondary particles formed by agglomeration of primary particles.
추가적으로, 평균 입경과 결정크기가 모두 성장한 1차 거대 입자를 포함하는 2차 소입자를 포함하는 소입자의 제2 양극 활물질의 경우에는, 상기 양극 활물질 전구체로 다공성인 입자를 사용할 수 있다. Additionally, in the case of the second positive electrode active material of small particles including secondary small particles including primary large particles having both grown in average particle size and crystal size, porous particles may be used as the positive electrode active material precursor.
이 때, 상기 제2 양극 활물질 전구체 제조를 위해 pH 농도를 제어할 수 있다. 구체적으로, pH가 7 내지 9가 되는 양으로 첨가될 수 있다.In this case, the pH concentration may be controlled to prepare the second cathode active material precursor. Specifically, it may be added in an amount such that the pH is 7 to 9.
이 후, 전술한 전구체와 리튬 원료 물질을 혼합하고 1차 소성한다. After that, the above-described precursor and lithium raw material are mixed, and primary firing is performed.
상기 리튬 원료물질로는 리튬 함유 황산염, 질산염, 아세트산염, 탄산염, 옥살산염, 시트르산염, 할라이드, 수산화물 또는 옥시수산화물 등이 사용될 수 있으며, 물에 용해될 수 있는 한 특별히 한정되지 않는다. 구체적으로 상기 리튬 원료물질은 Li2CO3, LiNO3, LiNO2, LiOH, LiOHㆍH2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li2SO4, CH3COOLi, 또는 Li3C6H5O7 등일 수 있으며, 이들 중 어느 하나 또는 둘 이상의 혼합물이 사용될 수 있다.The lithium raw material may include lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide or oxyhydroxide, and is not particularly limited as long as it is soluble in water. Specifically, the lithium raw material is Li 2 CO 3 , LiNO 3 , LiNO 2 , LiOH, LiOH·H 2 O, LiH, LiF, LiCl, LiBr, LiI, CH 3 COOLi, Li 2 O, Li 2 SO 4 , CH 3 COOLi, or Li 3 C 6 H 5 O 7 and the like, and any one or a mixture of two or more thereof may be used.
상기 1차 소성은 니켈(Ni)의 함량이 60몰% 이상인 고함량 니켈(High-Ni) NCM계 리튬 복합 전이금속 산화물의 경우, 800 내지 1,000℃로 소성할 수 있으며, 보다 바람직하게는 830 내지 980℃, 더욱 바람직하게는 850 내지 950℃로 소성할 수 있다. 니켈(Ni)의 함량이 60몰% 미만인 저함량 니켈(Low-Ni) NCM계 리튬 복합 전이금속 산화물의 경우, 1차 소성은 900 내지 1,100℃로 소성할 수 있으며, 보다 바람직하게는 930 내지 1,070℃, 더욱 바람직하게는 950 내지 1,050℃로 소성할 수 있다.The primary sintering may be sintered at 800 to 1,000° C., more preferably from 830 to 1,000° C., in the case of a high-Ni NCM-based lithium composite transition metal oxide having a nickel (Ni) content of 60 mol% or more. It may be sintered at 980°C, more preferably at 850 to 950°C. In the case of a low-content nickel (Low-Ni) NCM-based lithium composite transition metal oxide having a nickel (Ni) content of less than 60 mol%, the primary firing may be performed at 900 to 1,100° C., more preferably from 930 to 1,070° C. , more preferably at 950 to 1,050 °C.
상기 1차 소성은 공기 또는 산소 분위기 하에서 진행할 수 있으며, 15 내지 35시간 동안 수행할 수 있다.The primary firing may be carried out in an air or oxygen atmosphere, and may be performed for 15 to 35 hours.
다음으로, 상기 1차 소성 후 추가적인 2차 소성을 수행할 수 있다. Next, an additional secondary firing may be performed after the first firing.
상기 2차 소성은 니켈(Ni)의 함량이 60몰% 이상인 고함량 니켈(High-Ni) NCM계 리튬 복합 전이금속 산화물의 경우, 600 내지 950℃로 소성할 수 있으며, 보다 바람직하게는 650 내지 930℃, 더욱 바람직하게는 700 내지 900℃로 소성할 수 있다. 니켈(Ni)의 함량이 60몰% 미만인 저함량 니켈(Low-Ni) NCM계 리튬 복합 전이금속 산화물의 경우, 2차 소성은 700 내지 1,050℃로 소성할 수 있으며, 보다 바람직하게는 750 내지 1,000℃, 더욱 바람직하게는 800 내지 950℃로 소성할 수 있다.The secondary sintering may be performed at 600 to 950° C., more preferably 650 to 950° C. in the case of a high-Ni NCM-based lithium composite transition metal oxide having a nickel (Ni) content of 60 mol% or more. It can be calcined at 930°C, more preferably 700 to 900°C. In the case of a low-content nickel (Low-Ni) NCM-based lithium composite transition metal oxide having a nickel (Ni) content of less than 60 mol%, the secondary firing may be performed at 700 to 1,050° C., more preferably at 750 to 1,000° C. , more preferably at 800 to 950 °C.
상기 2차 소성은 공기 또는 산소 분위기 하에서 진행할 수 있으며, 10 내지 24시간 동안 수행할 수 있다.The secondary sintering may be performed under an air or oxygen atmosphere, and may be performed for 10 to 24 hours.
양극 및 리튬 이차 전지 Positive electrode and lithium secondary battery
본 발명의 또 다른 일 실시예에 따르면 상기 양극 활물질을 포함하는 리튬 이차전지용 양극 및 리튬 이차전지를 제공한다.According to another embodiment of the present invention, there is provided a positive electrode for a lithium secondary battery and a lithium secondary battery including the positive electrode active material.
구체적으로, 상기 양극은 양극 집전체 및 상기 양극 집전체 위에 형성되며, 상기 양극 활물질을 포함하는 양극 활물질층을 포함한다.Specifically, the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector and including the positive electrode active material.
상기 양극에 있어서, 양극 집전체는 전지에 화학적 변화를 유발하지 않으면서 도전성을 가진 것이라면 특별히 제한되는 것은 아니며, 예를 들어 스테인리스 스틸, 알루미늄, 니켈, 티탄, 소성 탄소 또는 알루미늄이나 스테인레스 스틸 표면에 탄소, 니켈, 티탄, 은 등으로 표면 처리한 것 등이 사용될 수 있다. 또한, 상기 양극 집전체는 통상적으로 3 내지 500㎛의 두께를 가질 수 있으며, 상기 양극 집전체 표면 상에 미세한 요철을 형성하여 양극 활물질의 접착력을 높일 수도 있다. 예를 들어 필름, 시트, 호일, 네트, 다공질체, 발포체, 부직포체 등 다양한 형태로 사용될 수 있다.In the positive electrode, the positive electrode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or carbon on the surface of aluminum or stainless steel. , nickel, titanium, silver, etc. may be used. In addition, the positive electrode current collector may typically have a thickness of 3 to 500 μm, and may increase the adhesion of the positive electrode active material by forming fine irregularities on the surface of the positive electrode current collector. For example, it may be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven body.
상기 양극 활물질층은 앞서 설명한 양극 활물질과 함께, 도전재 및 바인더를 포함할 수 있다.The positive active material layer may include a conductive material and a binder together with the above-described positive active material.
이때, 상기 도전재는 전극에 도전성을 부여하기 위해 사용되는 것으로서, 구성되는 전지에 있어서, 화학변화를 야기하지 않고 전자 전도성을 갖는 것이면 특별한 제한없이 사용가능하다. 구체적인 예로는 천연 흑연이나 인조 흑연 등의 흑연; 카본 블랙, 아세틸렌블랙, 케첸블랙, 채널 블랙, 퍼네이스 블랙, 램프 블랙, 서머 블랙, 탄소섬유 등의 탄소계 물질; 구리, 니켈, 알루미늄, 은 등의 금속 분말 또는 금속 섬유; 산화아연, 티탄산 칼륨 등의 도전성 위스커; 산화 티탄 등의 도전성 금속 산화물; 또는 폴리페닐렌 유도체 등의 전도성 고분자 등을 들 수 있으며, 이들 중 1종 단독 또는 2종 이상의 혼합물이 사용될 수 있다. 상기 도전재는 통상적으로 양극 활물질층 총 중량에 대하여 1 내지 30 중량%로 포함될 수 있다.In this case, the conductive material is used to impart conductivity to the electrode, and in the configured battery, it can be used without any particular limitation as long as it has electronic conductivity without causing chemical change. Specific examples include graphite such as natural graphite and artificial graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, summer black, and carbon fiber; metal powders or metal fibers, such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like, and one or a mixture of two or more thereof may be used. The conductive material may be included in an amount of 1 to 30% by weight based on the total weight of the positive active material layer.
또, 상기 바인더는 양극 활물질 입자들 간의 부착 및 양극 활물질과 양극 집전체와의 접착력을 향상시키는 역할을 한다. 구체적인 예로는 폴리비닐리덴플로라이드(PVDF), 비닐리덴플루오라이드-헥사플루오로프로필렌 코폴리머(PVDF-co-HFP), 폴리비닐알코올, 폴리아크릴로니트릴(polyacrylonitrile), 카르복시메틸셀룰로우즈(CMC), 전분, 히드록시프로필셀룰로우즈, 재생 셀룰로우즈, 폴리비닐피롤리돈, 테트라플루오로에틸렌, 폴리에틸렌, 폴리프로필렌, 에틸렌-프로필렌-디엔 폴리머(EPDM), 술폰화-EPDM, 스티렌 부타디엔 고무(SBR), 불소 고무, 또는 이들의 다양한 공중합체 등을 들 수 있으며, 이들 중 1종 단독 또는 2종 이상의 혼합물이 사용될 수 있다. 상기 바인더는 양극 활물질층 총 중량에 대하여 1 내지 30 중량%로 포함될 수 있다.In addition, the binder serves to improve adhesion between the positive electrode active material particles and the adhesive force between the positive electrode active material and the positive electrode current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC) ), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, or various copolymers thereof, and any one of them or a mixture of two or more thereof may be used. The binder may be included in an amount of 1 to 30% by weight based on the total weight of the positive electrode active material layer.
상기 양극은 상기한 양극 활물질을 이용하는 것을 제외하고는 통상의 양극 제조방법에 따라 제조될 수 있다. 구체적으로, 상기한 양극 활물질 및 선택적으로, 바인더 및 도전재를 포함하는 양극 활물질층 형성용 조성물을 양극 집전체 상에 도포한 후, 건조 및 압연함으로써 제조될 수 있다. 이때 상기 양극 활물질, 바인더, 도전재의 종류 및 함량은 앞서 설명한 바와 같다.The positive electrode may be manufactured according to a conventional positive electrode manufacturing method except for using the above positive electrode active material. Specifically, it may be prepared by applying the above-described positive electrode active material and, optionally, a composition for forming a positive electrode active material layer including a binder and a conductive material on a positive electrode current collector, followed by drying and rolling. In this case, the types and contents of the positive electrode active material, the binder, and the conductive material are as described above.
상기 용매로는 당해 기술분야에서 일반적으로 사용되는 용매일 수 있으며, 디메틸셀폭사이드(dimethyl sulfoxide, DMSO), 이소프로필 알코올(isopropyl alcohol), N-메틸피롤리돈(NMP), 아세톤(acetone) 또는 물 등을 들 수 있으며, 이들 중 1종 단독 또는 2종 이상의 혼합물이 사용될 수 있다. 상기 용매의 사용량은 슬러리의 도포 두께, 제조 수율을 고려하여 상기 양극 활물질, 도전재 및 바인더를 용해 또는 분산시키고, 이후 양극제조를 위한 도포시 우수한 두께 균일도를 나타낼 수 있는 점도를 갖도록 하는 정도면 충분하다.The solvent may be a solvent generally used in the art, dimethyl sulfoxide (DMSO), isopropyl alcohol (isopropyl alcohol), N-methylpyrrolidone (NMP), acetone (acetone) or water, and the like, and any one of them or a mixture of two or more thereof may be used. The amount of the solvent used is enough to dissolve or disperse the positive electrode active material, the conductive material and the binder in consideration of the application thickness of the slurry and the production yield, and to have a viscosity capable of exhibiting excellent thickness uniformity when applied for the production of the positive electrode thereafter. Do.
또, 다른 방법으로, 상기 양극은 상기 양극 활물질층 형성용 조성물을 별도의 지지체 상에 캐스팅한 다음, 이 지지체로부터 박리하여 얻은 필름을 양극 집전체 상에 라미네이션함으로써 제조될 수도 있다.Alternatively, the positive electrode may be manufactured by casting the composition for forming the positive electrode active material layer on a separate support, and then laminating a film obtained by peeling it from the support on the positive electrode current collector.
본 발명의 또 다른 일 실시예에 따르면, 상기 양극을 포함하는 전기화학소자가 제공된다. 상기 전기화학소자는 구체적으로 전지 또는 커패시터 등일 수 있으며, 보다 구체적으로는 리튬 이차전지일 수 있다.According to another embodiment of the present invention, an electrochemical device including the positive electrode is provided. The electrochemical device may specifically be a battery or a capacitor, and more specifically, may be a lithium secondary battery.
상기 리튬 이차전지는 구체적으로 양극, 상기 양극과 대향하여 위치하는 음극, 상기 양극과 음극 사이에 개재되는 세퍼레이터 및 전해질을 포함하며, 상기 양극은 앞서 설명한 바와 같다. 또, 상기 리튬 이차전지는 상기 양극, 음극, 세퍼레이터의 전극 조립체를 수납하는 전지용기, 및 상기 전지용기를 밀봉하는 밀봉 부재를 선택적으로 더 포함할 수 있다. The lithium secondary battery specifically includes a positive electrode, a negative electrode positioned to face the positive electrode, a separator and an electrolyte interposed between the positive electrode and the negative electrode, and the positive electrode is as described above. In addition, the lithium secondary battery may optionally further include a battery container for accommodating the electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member for sealing the battery container.
상기 리튬 이차전지에 있어서, 상기 음극은 음극 집전체 및 상기 음극 집전체 상에 위치하는 음극 활물질층을 포함한다.In the lithium secondary battery, the negative electrode includes a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector.
상기 음극 집전체는 전지에 화학적 변화를 유발하지 않으면서 높은 도전성을 가지는 것이라면 특별히 제한되는 것은 아니며, 예를 들어, 구리, 스테인레스 스틸, 알루미늄, 니켈, 티탄, 소성 탄소, 구리나 스테인레스 스틸의 표면에 탄소, 니켈, 티탄, 은 등으로 표면처리한 것, 알루미늄-카드뮴 합금 등이 사용될 수 있다. 또, 상기 음극 집전체는 통상적으로 3 내지 500㎛의 두께를 가질 수 있으며, 양극 집전체와 마찬가지로, 상기 집전체 표면에 미세한 요철을 형성하여 음극 활물질의 결합력을 강화시킬 수도 있다. 예를 들어, 필름, 시트, 호일, 네트, 다공질체, 발포체, 부직포체 등 다양한 형태로 사용될 수 있다.The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel surface. Carbon, nickel, titanium, silver, etc. surface-treated, aluminum-cadmium alloy, etc. may be used. In addition, the negative electrode current collector may have a thickness of typically 3 to 500 μm, and similarly to the positive electrode current collector, fine concavities and convexities may be formed on the surface of the current collector to strengthen the bonding force of the negative electrode active material. For example, it may be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven body.
상기 음극 활물질층은 음극 활물질과 함께 선택적으로 바인더 및 도전재를 포함한다. 상기 음극 활물질층은 일례로서 음극 집전체 상에 음극 활물질, 및 선택적으로 바인더 및 도전재를 포함하는 음극 형성용 조성물을 도포하고 건조하거나, 또는 상기 음극 형성용 조성물을 별도의 지지체 상에 캐스팅한 다음, 이 지지체로부터 박리하여 얻은 필름을 음극 집전체 상에 라미네이션함으로써 제조될 수도 있다.The anode active material layer optionally includes a binder and a conductive material together with the anode active material. The anode active material layer may be formed by applying a composition for forming an anode including an anode active material and, optionally, a binder and a conductive material on an anode current collector and drying, or casting the composition for forming a cathode on a separate support, and then , may be produced by laminating a film obtained by peeling from this support onto a negative electrode current collector.
상기 음극 활물질로는 리튬의 가역적인 인터칼레이션 및 디인터칼레이션이 가능한 화합물이 사용될 수 있다. 구체적인 예로는 인조흑연, 천연흑연, 흑연화 탄소섬유, 비정질탄소 등의 탄소질 재료; Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si합금, Sn합금 또는 Al합금 등 리튬과 합금화가 가능한 금속질 화합물; SiOβ(0 < β < 2), SnO2, 바나듐 산화물, 리튬 바나듐 산화물과 같이 리튬을 도프 및 탈도프할 수 있는 금속산화물; 또는 Si-C 복합체 또는 Sn-C 복합체과 같이 상기 금속질 화합물과 탄소질 재료를 포함하는 복합물 등을 들 수 있으며, 이들 중 어느 하나 또는 둘 이상의 혼합물이 사용될 수 있다. 또한, 상기 음극활물질로서 금속 리튬 박막이 사용될 수도 있다. 또, 탄소재료는 저결정 탄소 및 고결정성 탄소 등이 모두 사용될 수 있다. 저결정성 탄소로는 연화탄소 (soft carbon) 및 경화탄소 (hard carbon)가 대표적이며, 고결정성 탄소로는 무정형, 판상, 인편상, 구형 또는 섬유형의 천연 흑연 또는 인조 흑연, 키시흑연 (Kish graphite), 열분해 탄소 (pyrolytic carbon), 액정피치계 탄소섬유 (mesophase pitch based carbon fiber), 탄소 미소구체 (meso-carbon microbeads), 액정피치 (Mesophase pitches) 및 석유와 석탄계 코크스 (petroleum or coal tar pitch derived cokes) 등의 고온 소성탄소가 대표적이다.As the anode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metal compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; metal oxides capable of doping and dedoping lithium, such as SiOβ (0 < β < 2), SnO 2 , vanadium oxide, and lithium vanadium oxide; Alternatively, a composite including the metallic compound and a carbonaceous material such as a Si-C composite or a Sn-C composite may be used, and any one or a mixture of two or more thereof may be used. In addition, a metal lithium thin film may be used as the negative electrode active material. In addition, as the carbon material, both low crystalline carbon and high crystalline carbon may be used. As low crystalline carbon, soft carbon and hard carbon are representative, and as high crystalline carbon, amorphous, plate-like, flaky, spherical or fibrous natural or artificial graphite, Kish graphite (Kish) graphite), pyrolytic carbon, mesophase pitch based carbon fiber, meso-carbon microbeads, liquid crystal pitches (Mesophase pitches), and petroleum and coal tar pitch (petroleum or coal tar pitch) High-temperature calcined carbon such as derived cokes) is a representative example.
또, 상기 바인더 및 도전재는 앞서 양극에서 설명한 바와 동일한 것일 수 있다.In addition, the binder and the conductive material may be the same as those described above for the positive electrode.
한편, 상기 리튬 이차전지에 있어서, 세퍼레이터는 음극과 양극을 분리하고 리튬 이온의 이동 통로를 제공하는 것으로, 통상 리튬 이차전지에서 세퍼레이터로 사용되는 것이라면 특별한 제한 없이 사용가능하며, 특히 전해질의 이온 이동에 대하여 저저항이면서 전해액 함습 능력이 우수한 것이 바람직하다. 구체적으로는 다공성 고분자 필름, 예를 들어 에틸렌 단독중합체, 프로필렌 단독중합체, 에틸렌/부텐 공중합체, 에틸렌/헥센 공중합체 및 에틸렌/메타크릴레이트 공중합체 등과 같은 폴리올레핀계 고분자로 제조한 다공성 고분자 필름 또는 이들의 2층 이상의 적층 구조체가 사용될 수 있다. 또 통상적인 다공성 부직포, 예를 들어 고융점의 유리 섬유, 폴리에틸렌테레프탈레이트 섬유 등으로 된 부직포가 사용될 수도 있다. 또, 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.On the other hand, in the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a passage for the movement of lithium ions, and can be used without particular limitation as long as it is usually used as a separator in a lithium secondary battery, especially for the movement of ions in the electrolyte It is preferable to have a low resistance to respect and an excellent electrolyte moisture content. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer, and ethylene/methacrylate copolymer, or these A laminate structure of two or more layers of may be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high melting point glass fiber, polyethylene terephthalate fiber, etc. may be used. In addition, a coated separator containing a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.
또, 본 발명에서 사용되는 전해질로는 리튬 이차전지 제조시 사용 가능한 유기계 액체 전해질, 무기계 액체 전해질, 고체 고분자 전해질, 겔형 고분자 전해질, 고체 무기 전해질, 용융형 무기 전해질 등을 들 수 있으며, 이들로 한정되는 것은 아니다. In addition, examples of the electrolyte used in the present invention include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, and the like, which can be used in the manufacture of lithium secondary batteries, and are limited to these. it is not going to be
구체적으로, 상기 전해질은 유기 용매 및 리튬염을 포함할 수 있다. Specifically, the electrolyte may include an organic solvent and a lithium salt.
상기 유기 용매로는 전지의 전기 화학적 반응에 관여하는 이온들이 이동할 수 있는 매질 역할을 할 수 있는 것이라면 특별한 제한없이 사용될 수 있다. 구체적으로 상기 유기 용매로는, 메틸 아세테이트(methyl acetate), 에틸 아세테이트(ethyl acetate), γ-부티로락톤(γ-butyrolactone), ε-카프로락톤(ε-caprolactone) 등의 에스테르계 용매; 디부틸 에테르(dibutyl ether) 또는 테트라히드로퓨란(tetrahydrofuran) 등의 에테르계 용매; 시클로헥사논(cyclohexanone) 등의 케톤계 용매; 벤젠(benzene), 플루오로벤젠(fluorobenzene) 등의 방향족 탄화수소계 용매; 디메틸카보네이트(dimethylcarbonate, DMC), 디에틸카보네이트(diethylcarbonate, DEC), 에틸메틸카보네이트(ethylmethylcarbonate, EMC), 에틸렌카보네이트(ethylene carbonate, EC), 프로필렌카보네이트(propylene carbonate, PC) 등의 카보네이트계 용매; 에틸알코올, 이소프로필 알코올 등의 알코올계 용매; R-CN(R은 C2 내지 C20의 직쇄상, 분지상 또는 환 구조의 탄화수소기이며, 이중결합 방향 환 또는 에테르 결합을 포함할 수 있다) 등의 니트릴류; 디메틸포름아미드 등의 아미드류; 1,3-디옥솔란 등의 디옥솔란류; 또는 설포란(sulfolane)류 등이 사용될 수 있다. 이중에서도 카보네이트계 용매가 바람직하고, 전지의 충방전 성능을 높일 수 있는 고유전율을 갖는 환형 카보네이트(예를 들면, 에틸렌카보네이트 또는 프로필렌카보네이트 등)와 저점도의 선형 카보네이트계 화합물(예를 들면, 에틸메틸카보네이트, 디메틸카보네이트 또는 디에틸카보네이트 등)의 혼합물이 보다 바람직하다. 이 경우 환형 카보네이트와 사슬형 카보네이트는 약 1:1 내지 약 1:9의 부피비로 혼합하여 사용하는 것이 전해액의 성능이 우수하게 나타날 수 있다. The organic solvent may be used without any particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, as the organic solvent, ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon-based solvents such as benzene and fluorobenzene; carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (R is a C2 to C20 linear, branched or cyclic hydrocarbon group, which may include a double bond aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; Or sulfolane may be used. Among these, carbonate-based solvents are preferable, and cyclic carbonates (eg, ethylene carbonate or propylene carbonate, etc.) having a high dielectric constant capable of increasing the charge/discharge performance of the battery and a low-viscosity linear carbonate-based compound (eg, ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferable. In this case, when the cyclic carbonate and the chain carbonate are mixed in a volume ratio of about 1:1 to about 1:9, the performance of the electrolyte may be excellent.
상기 리튬염은 리튬 이차전지에서 사용되는 리튬 이온을 제공할 수 있는 화합물이라면 특별한 제한 없이 사용될 수 있다. 구체적으로 상기 리튬염은, LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2. LiCl, LiI, 또는 LiB(C2O4)2 등이 사용될 수 있다. 상기 리튬염의 농도는 0.1 내지 2.0M 범위 내에서 사용하는 것이 좋다. 리튬염의 농도가 상기 범위에 포함되면, 전해질이 적절한 전도도 및 점도를 가지므로 우수한 전해질 성능을 나타낼 수 있고, 리튬 이온이 효과적으로 이동할 수 있다.The lithium salt may be used without particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt is LiPF 6 , LiClO 4 , LiAsF 6 , LiBF 4 , LiSbF 6 , LiAl0 4 , LiAlCl 4 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiN(C 2 F 5 SO 3 ) 2 , LiN(C 2 F 5 SO 2 ) 2 , LiN(CF 3 SO 2 ) 2 . LiCl, LiI, or LiB(C 2 O 4 ) 2 , etc. may be used. The concentration of the lithium salt is preferably used within the range of 0.1 to 2.0M. When the concentration of the lithium salt is included in the above range, the electrolyte may exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions may move effectively.
상기 전해질에는 상기 전해질 구성 성분들 외에도 전지의 수명특성 향상, 전지 용량 감소 억제, 전지의 방전 용량 향상 등을 목적으로 예를 들어, 디플루오로 에틸렌카보네이트 등과 같은 할로알킬렌카보네이트계 화합물, 피리딘, 트리에틸포스파이트, 트리에탄올아민, 환상 에테르, 에틸렌 디아민, n-글라임(glyme), 헥사인산 트리아미드, 니트로벤젠 유도체, 유황, 퀴논 이민 염료, N-치환 옥사졸리디논, N,N-치환 이미다졸리딘, 에틸렌 글리콜 디알킬 에테르, 암모늄염, 피롤, 2-메톡시 에탄올 또는 삼염화 알루미늄 등의 첨가제가 1종 이상 더 포함될 수도 있다. 이때 상기 첨가제는 전해질 총 중량에 대하여 0.1 내지 5 중량%로 포함될 수 있다. In the electrolyte, in addition to the electrolyte components, for the purpose of improving battery life characteristics, suppressing battery capacity reduction, and improving battery discharge capacity, for example, haloalkylene carbonate-based compounds such as difluoroethylene carbonate, pyridine, tri Ethyl phosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imida One or more additives such as jolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol or aluminum trichloride may be further included. In this case, the additive may be included in an amount of 0.1 to 5% by weight based on the total weight of the electrolyte.
본 발명에 따른 양극 활물질을 포함하는 리튬 이차전지는 휴대전화, 노트북 컴퓨터, 디지털 카메라 등의 휴대용 기기, 및 하이브리드 전기자동차(hybrid electric vehicle, HEV) 등의 전기 자동차 분야 등에 유용하다. The lithium secondary battery including the positive electrode active material according to the present invention is useful in the field of portable devices such as mobile phones, notebook computers, digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).
이에 따라, 본 발명의 다른 일 구현예에 따르면, 상기 리튬 이차전지를 단위 셀로 포함하는 전지 모듈 및 이를 포함하는 전지팩이 제공된다. Accordingly, according to another embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.
상기 전지모듈 또는 전지팩은 파워 툴(Power Tool); 전기자동차(Electric Vehicle, EV), 하이브리드 전기자동차, 및 플러그인 하이브리드 전기자동차(Plug-in Hybrid Electric Vehicle, PHEV)를 포함하는 전기차; 또는 전력 저장용 시스템 중 어느 하나 이상의 중대형 디바이스 전원으로 이용될 수 있다.The battery module or battery pack is a power tool (Power Tool); electric vehicles, including electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); Alternatively, it may be used as a power source for any one or more medium-to-large devices in a system for power storage.
이하, 본 발명이 속하는 기술 분야에서 통상의 지식을 가진 자가 용이하게 실시할 수 있도록 본 발명의 실시예에 대하여 상세히 설명한다. 그러나 본 발명은 여러 가지 상이한 형태로 구현될 수 있으며 여기에서 설명하는 실시예에 한정되지 않는다. Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.
실시예 1.Example 1.
실시예 1에서는, 평균 직경(D50)이 15 ㎛인 2차 대입자를 포함하는 제1 양극 활물질과, 평균 직경(D50)이 4 ㎛인 2차 소입자를 포함하는 제2 양극 활물질을 60 : 40 (중량비)로 혼합하여 양극 활물질로 사용하였다. 이 때 2차 소입자는 직경이 1㎛ 이상인 1차 거대 입자가 10개 이내로 응집되어 있는 2차 입자이다. In Example 1, the first positive electrode active material including large secondary particles having an average diameter (D50) of 15 μm and the second positive active material including secondary small particles having an average diameter (D50) of 4 μm were mixed at 60:40. (weight ratio) was mixed and used as a positive electrode active material. In this case, the secondary small particles are secondary particles in which 10 or less primary large particles having a diameter of 1 μm or more are aggregated.
구체적으로, 다음과 같이 양극 활물질을 제조하였다:Specifically, a positive electrode active material was prepared as follows:
(대입자의 제1 양극 활물질의 제조)(Preparation of first positive electrode active material of large particles)
공침 반응기(용량 20L)에 증류수 4리터를 넣은 뒤 50℃온도를 유지시키며 28중량% 농도의 암모니아 수용액 100mL를 투입한 후, NiSO4, CoSO4, MnSO4를 니켈:코발트:망간의 몰비가 0.8:0.1:0.1이 되도록 혼합된 3.2mol/L 농도의 전이금속 용액을 300mL/hr, 28중량%의 암모니아 수용액을 42mL/hr로 반응기에 연속적으로 투입하였다. 임펠러의 속도는 400rpm으로 교반하였고, pH 유지를 위해 40중량%의 수산화나트륨 용액을 이용하여 pH가 11.0이 유지되도록 투입하였다. 24시간 공침 반응시켜 전구체 입자를 형성하였다. 상기 전구체 입자를 분리하여 세척 후 130 ℃의 오븐에서 건조하여 전구체를 제조하였다. After putting 4 liters of distilled water into the coprecipitation reactor (capacity 20L), maintaining the temperature at 50°C, and adding 100 mL of 28 wt% aqueous ammonia solution, NiSO 4 , CoSO 4 , MnSO 4 Molar ratio of nickel: cobalt: manganese is 0.8 : A 3.2 mol/L concentration of a transition metal solution mixed to be 0.1:0.1 was continuously added to the reactor at 300 mL/hr, and a 28 wt% aqueous ammonia solution was added to the reactor at 42 mL/hr. The speed of the impeller was stirred at 400 rpm, and 40% by weight of sodium hydroxide solution was used to maintain the pH so that the pH was maintained at 11.0. The precursor particles were formed by co-precipitation reaction for 24 hours. The precursor particles were separated, washed, and dried in an oven at 130° C. to prepare a precursor.
공침 반응으로 합성된 Ni0.8Co0.1Mn0.1(OH)2 전구체를 Li2CO3와 Li/Me(Ni, Co, Mn) 몰비가 1.05가 되도록 혼합하고, 산소 분위기 800 ℃에서 10시간 열처리하여 LiNi0.8Co0.1Mn0.1O2 리튬 복합 전이금속 산화물 제1 양극 활물질을 제조하였다. The Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 precursor synthesized by the co-precipitation reaction was mixed with Li 2 CO 3 and Li/Me (Ni, Co, Mn) in a molar ratio of 1.05, followed by heat treatment at 800 ° C. in an oxygen atmosphere for 10 hours to form LiNi 0.8 Co 0.1 Mn 0.1 O 2 A lithium composite transition metal oxide first positive active material was prepared.
(소입자의 제2 양극 활물질의 제조)(Preparation of second positive electrode active material of small particles)
전구체 제조에서 공침 반응시 pH를 9로 제어하고, 공침 반응 시간을 10시간으로 변경하고, 이후 열처리 조건을 850℃로 변경한 것을 제외하고는 대입자의 제1 양극 활물질 제조와 동일한 방법으로 제2 양극 활물질을 합성하였다.The second positive electrode was prepared in the same manner as in preparing the first positive active material of large particles, except that the pH was controlled to 9 during the coprecipitation reaction in the precursor preparation, the coprecipitation reaction time was changed to 10 hours, and the heat treatment conditions were changed to 850° C. The active material was synthesized.
실시예 2.Example 2.
실시예 2에서는, 평균 직경(D50)이 10 ㎛인 2차 대입자를 포함하는 제1 양극 활물질과, 평균 직경(D50)이 4 ㎛인 2차 소입자를 포함하는 제2 양극 활물질을 60 : 40(중량비)로 혼합하여 양극 활물질로 사용하였다. 이 때 2차 소입자는 직경이 1㎛ 이상인 1차 거대 입자가 10개 이내로 응집되어 있는 2차 입자이다. In Example 2, the first positive active material including large secondary particles having an average diameter (D50) of 10 μm and the second positive active material including secondary small particles having an average diameter (D50) of 4 μm were mixed at 60:40. (weight ratio) was mixed and used as a positive electrode active material. In this case, the secondary small particles are secondary particles in which 10 or less primary large particles having a diameter of 1 μm or more are aggregated.
구체적으로, 다음과 같이 양극 활물질을 제조하였다:Specifically, a positive electrode active material was prepared as follows:
제1 양극 활물질은 실시예 1의 대입자의 제1 양극 활물질의 제조에서 공침 시간을 15시간으로 변경한 것을 제외하고는 동일한 방법으로 제조하였다. 제2 양극 활물질은 실시예 1과 동일한 방법으로 합성하였다.The first positive active material was prepared in the same manner as in Example 1, except that the co-precipitation time was changed to 15 hours in the preparation of the first positive active material of large particles. The second positive active material was synthesized in the same manner as in Example 1.
비교예 1. Comparative Example 1 .
비교예 1에서는, 평균 직경(D50)이 15 ㎛인 2차 대입자를 포함하는 제1 양극 활물질과, 평균 직경(D50)이 4 ㎛인 2차 입자 소입자를 포함하는 제2 양극 활물질을 80 : 20 (중량비)로 혼합하여 양극 활물질로 사용하였다. 이 때 2차 입자 소입자는 직경이 0.5 ㎛ 이하인 1차 미세 입자가 응집되어 있는 2차 입자이다. In Comparative Example 1, 80: a first positive active material including large secondary particles having an average diameter (D50) of 15 μm, and a second positive active material including small secondary particles having an average diameter (D50) of 4 μm: 20 (weight ratio) was mixed and used as a positive electrode active material. In this case, the secondary particle small particle is a secondary particle in which primary fine particles having a diameter of 0.5 μm or less are aggregated.
구체적으로, 다음과 같이 양극 활물질을 제조하였다:Specifically, a positive electrode active material was prepared as follows:
제1 양극 활물질은 실시예 1.의 대입자의 제1 양극 활물질의 제조와 동일한 방법으로 제조하였다. 제2 양극 활물질은, 실시예 1의 소입자의 제2 양극 활물질의 제조에서 전구체 합성시 pH를 11로 제어하고 열처리 800 ℃으로 변경한 것을 제외하고는 동일한 방법으로 양극재를 합성하였다. The first positive active material was prepared in the same manner as in the preparation of the first positive active material of large particles in Example 1. The second cathode active material was synthesized in the same manner as in Example 1, except that in the preparation of the second cathode active material of small particles, the pH was controlled to 11 when synthesizing the precursor and the heat treatment was changed to 800°C.
비교예 2. Comparative Example 2 .
2차 대입자와 2차 소입자의 중량비를 60 : 40이 아닌 80 : 20으로 제어한 것을 제외하고는 실시예 1과 동일한 방법으로 양극 활물질을 제조하였다. 이 때 2차 소입자는 직경이 1㎛ 이상인 1차 거대 입자가 10개 이내로 응집되어 있는 2차 입자이다. A cathode active material was prepared in the same manner as in Example 1, except that the weight ratio of the secondary large particles to the secondary small particles was controlled to 80:20 instead of 60:40. In this case, the secondary small particles are secondary particles in which 10 or less primary large particles having a diameter of 1 μm or more are aggregated.
비교예 3. Comparative Example 3 .
2차 대입자와 2차 입자 소입자의 중량비를 80 : 20이 아닌 60 : 40으로 제어한 것을 제외하고는 비교예 1과 동일한 방법으로 양극 활물질을 제조하였다. 이 때 2차 입자 소입자는 직경이 0.5 ㎛ 이하인 1차 미세 입자가 응집되어 있는 2차 입자이다.A positive electrode active material was prepared in the same manner as in Comparative Example 1, except that the weight ratio of the secondary large particles and the secondary particles small particles was controlled to 60:40 instead of 80:20. In this case, the secondary particle small particle is a secondary particle in which primary fine particles having a diameter of 0.5 μm or less are aggregated.
비교예 4. Comparative Example 4 .
비교예 4에서는, 평균 직경(D50)이 10 ㎛인 2차 대입자를 포함하는 제1 양극 활물질과, 평균 직경(D50)이 4 ㎛인 2차 입자 소입자를 포함하는 제2 양극 활물질을 80 : 20 (중량비)로 혼합하여 양극 활물질로 사용하였다. 이 때 2차 입자 소입자는 직경이 0.5 ㎛ 이하인 1차 미세 입자가 응집되어 있는 2차 입자이다. In Comparative Example 4, a first positive active material including large secondary particles having an average diameter (D50) of 10 μm and a second positive active material including small secondary particles having an average diameter (D50) of 4 μm were prepared by mixing 80: 20 (weight ratio) was mixed and used as a positive electrode active material. In this case, the secondary particle small particle is a secondary particle in which primary fine particles having a diameter of 0.5 μm or less are aggregated.
구체적으로, 다음과 같이 양극 활물질을 제조하였다:Specifically, a positive electrode active material was prepared as follows:
제1 양극 활물질은 실시예 2의 대입자의 제1 양극 활물질의 제조와 과 동일한 방법으로 제조하였다. 제2 양극 활물질은 비교예 1의 제2 양극 활물질의 제조와 동일한 방법으로 합성하였다.The first positive active material was prepared in the same manner as in the preparation of the first positive active material of large particles in Example 2. The second positive active material was synthesized in the same manner as in the preparation of the second positive active material of Comparative Example 1.
비교예 5. Comparative Example 5 .
비교예 5에서는, 2차 대입자와 2차 입자 소입자의 중량비를 60 : 40이 아닌 80 : 20으로 변경한 것을 제외하고는 실시예 2와 동일한 방법으로 양극 활물질을 제조하였다.In Comparative Example 5, a cathode active material was prepared in the same manner as in Example 2, except that the weight ratio of the secondary large particles and the secondary particles was changed to 80:20 instead of 60:40.
비교예 6. Comparative Example 6 .
비교예 6에서는, 2차 대입자와 2차 입자 소입자의 중량비를 80 : 20이 아닌 60 : 40으로 제어한 것을 제외하고는 비교예 4와 동일한 방법으로 양극 활물질을 제조하였다.In Comparative Example 6, a cathode active material was prepared in the same manner as in Comparative Example 4, except that the weight ratio of the secondary large particles to the secondary particles was controlled to 60:40 instead of 80:20.
비교예 7. Comparative Example 7 .
비교예 7에서는, 평균 직경(D50)이 8 ㎛인 2차 대입자를 포함하는 제1 양극 활물질과, 평균 직경(D50)이 4 ㎛인 2차 소입자를 포함하는 제2 양극 활물질을 80 : 20(중량비)로 혼합하여 양극 활물질로 사용하였다. 이 때 2차 입자 소입자는 직경이 0.5 ㎛ 이하인 1차 미세 입자가 응집되어 있는 2차 입자이다.In Comparative Example 7, the first positive active material including large secondary particles having an average diameter (D50) of 8 μm and the second positive active material including small secondary particles having an average diameter (D50) of 4 μm were mixed at 80:20. (weight ratio) was mixed and used as a positive electrode active material. In this case, the secondary particle small particle is a secondary particle in which primary fine particles having a diameter of 0.5 μm or less are aggregated.
구체적으로, 다음과 같이 양극 활물질을 제조하였다:Specifically, a positive electrode active material was prepared as follows:
제1 양극 활물질은 실시예 1의 대입자의 제1 양극 활물질의 제조에서 공침 시간을 10 시간으로 변경한 것을 제외하고는 동일한 방법으로 제조하였다. 제2 양극 활물질은 비교예 1과 동일한 방법으로 합성하였다.The first positive active material was prepared in the same manner as in Example 1, except that the co-precipitation time was changed to 10 hours in the preparation of the first positive active material of large particles. The second positive active material was synthesized in the same manner as in Comparative Example 1.
비교예 8. Comparative Example 8 .
비교예 8에서는, 평균 직경(D50)이 8 ㎛인 2차 대입자를 포함하는 제1 양극 활물질과, 평균 직경(D50)이 4 ㎛인 2차 소입자를 포함하는 제2 양극 활물질을 80 : 20(중량비)로 혼합하여 양극 활물질로 사용하였다. 이 때 2차 소입자는 직경이 1㎛ 이상인 1차 거대 입자가 10개 이내로 응집되어 있는 2차 입자이다.In Comparative Example 8, the first positive active material including large secondary particles having an average diameter (D50) of 8 μm and the second positive active material including small secondary particles having an average diameter (D50) of 4 μm were mixed at 80:20. (weight ratio) was mixed and used as a positive electrode active material. In this case, the secondary small particles are secondary particles in which 10 or less primary large particles having a diameter of 1 μm or more are aggregated.
구체적으로, 다음과 같이 양극 활물질을 제조하였다:Specifically, a positive electrode active material was prepared as follows:
제1 양극 활물질은 비교예 7과 동일한 방법으로 제조하였다. 제2 양극 활물질은 실시예 1과 동일한 방법으로 합성하였다.The first positive active material was prepared in the same manner as in Comparative Example 7. The second positive active material was synthesized in the same manner as in Example 1.
비교예 9. Comparative Example 9 .
비교예 9에서는, 2차 대입자와 2차 입자 소입자의 중량비를 80 : 20이 아닌 60 : 40으로 제어한 것을 제외하고는 비교예 7와 동일한 방법으로 양극 활물질을 제조하였다.In Comparative Example 9, a cathode active material was prepared in the same manner as in Comparative Example 7, except that the weight ratio of the secondary large particles to the secondary particles was controlled to be 60:40 instead of 80:20.
비교예 10. Comparative Example 10 .
비교예 10에서는, 평균 직경(D50)이 15 ㎛인 2차 대입자를 포함하는 제1 양극 활물질만을 사용한 경우이다. In Comparative Example 10, only the first positive active material including secondary large particles having an average diameter (D50) of 15 μm was used.
구체적으로, 다음과 같이 양극 활물질을 제조하였다:Specifically, a positive electrode active material was prepared as follows:
제1 양극 활물질은 실시예 1의 대입자의 제1 양극 활물질의 제조와 동일한 방법으로 합성하였다.The first positive active material was synthesized in the same manner as in the preparation of the first positive active material of large particles in Example 1.
비교예 11. Comparative Example 11 .
비교예 11에서는, 평균 직경(D50)이 10 ㎛인 2차 대입자를 포함하는 제1 양극 활물질만을 사용한 경우이다. In Comparative Example 11, only the first positive active material including secondary large particles having an average diameter (D50) of 10 μm was used.
구체적으로, 다음과 같이 양극 활물질을 제조하였다:Specifically, a positive electrode active material was prepared as follows:
제1 양극 활물질은 실시예 2의 대입자의 제1 양극 활물질의 제조와 동일한 방법으로 합성하였다.The first positive active material was synthesized in the same manner as in the preparation of the first positive active material of large particles of Example 2.
비교예 12. Comparative Example 12 .
비교예 12에서는, 평균 직경(D50)이 8 ㎛인 2차 대입자를 포함하는 제1 양극 활물질만을 사용한 경우이다. In Comparative Example 12, only the first positive active material including secondary large particles having an average diameter (D50) of 8 μm was used.
구체적으로, 다음과 같이 양극 활물질을 제조하였다:Specifically, a positive electrode active material was prepared as follows:
제1 양극 활물질은 비교예 7의 대입자의 제1 양극 활물질의 제조와 동일한 방법으로 합성하였다.The first positive active material was synthesized in the same manner as in the preparation of the first positive active material of the large particles of Comparative Example 7.
비교예 13. Comparative Example 13 .
비교예 13은, 평균 직경(D50)이 4 ㎛인 2차 소입자를 포함하는 제1 양극 활물질만을 사용한 경우이다. 이 때 2차 소입자는 직경이 1㎛ 이상인 1차 거대 입자가 10개 이내로 응집되어 있는 2차 입자이다. Comparative Example 13 is a case in which only the first positive active material including secondary small particles having an average diameter (D50) of 4 μm is used. In this case, the secondary small particles are secondary particles in which 10 or less primary large particles having a diameter of 1 μm or more are aggregated.
구체적으로, 다음과 같이 양극 활물질을 제조하였다:Specifically, a positive electrode active material was prepared as follows:
제1 양극 활물질은, 실시예 1의 소입자의 제2 양극 활물질의 제조와 동일한 방법으로 합성하였다.The first positive active material was synthesized in the same manner as in the preparation of the second positive active material of small particles of Example 1.
D50D50 실시예 1Example 1 실시예 2Example 2 비교예 1Comparative Example 1 비교예 2Comparative Example 2 비교예 3Comparative Example 3 비교예 4Comparative Example 4 비교예 5Comparative Example 5 비교예 6Comparative Example 6 비교예 7Comparative Example 7 비교예 8Comparative Example 8 비교예 9Comparative Example 9 비교예 10Comparative Example 10 비교예 11Comparative Example 11 비교예 12Comparative Example 12 비교예 13Comparative Example 13
2차 대입자
(=2차 입자 대입자)secondary lender
(=secondary particle large particle) 		15㎛15㎛ 6060 8080 8080 6060 100100
10㎛10㎛ 6060 8080 8080 6060 100100
8㎛8㎛ 8080 8080 6060 100100
2차 입자 소입자
(1차 미세입자 응집) secondary particle small particle
(Primary fine particle agglomeration) 		4㎛4㎛ 2020 4040 2020 4040 2020 4040
2차 소입자
(1차 거대입자 응집)secondary small particle
(primary macroparticle aggregation) 		4㎛4㎛ 4040 4040 2020 2020 2020 100100
[실험예 1: 조성에 따른 양극 압연 조건에서의 1 ㎛ 미만의 미분 존재 비율][Experimental Example 1: Existence ratio of fines of less than 1 μm in anodized rolling conditions according to composition]
상기 실시예 1,2 및 비교예 1 내지 13에서 제조된 양극 활물질을 각각의 양극 활물질, 카본블랙 도전재 및 PVdF 바인더를 N-메틸피롤리돈 용매 중에서 중량비로 96:2:2의 비율로 혼합하여 양극 슬러리를 제조하고, 이를 알루미늄 집전체의 일면에 도포한 후, 100℃에서 건조 후, 기공도 25%로 압연하여 양극을 제조하였다. 제조된 양극을 500℃ 대기 조건에서 10시간 동안 열처리하여 바인더와 도전재를 제거하였다. 이후 나머지 양극 활물질 분말을 회수하여 입도 분포를 측정하였으며, 그 결과를 하기 표 2 내지 4에 나타내었다.The positive active materials prepared in Examples 1 and 2 and Comparative Examples 1 to 13 were mixed with each positive active material, carbon black conductive material, and PVdF binder in an N-methylpyrrolidone solvent in a weight ratio of 96:2:2. to prepare a positive electrode slurry, which was applied to one surface of an aluminum current collector, dried at 100° C., and rolled to a porosity of 25% to prepare a positive electrode. The prepared positive electrode was heat-treated at 500° C. in atmospheric conditions for 10 hours to remove the binder and the conductive material. Thereafter, the remaining cathode active material powder was recovered and particle size distribution was measured, and the results are shown in Tables 2 to 4 below.
비교예 11Comparative Example 11 비교예 1Comparative Example 1 비교예 3Comparative Example 3 비교예 2Comparative Example 2 실시예 1Example 1 비교예 13Comparative Example 13
2차 대입자 : 2차소입자의 중량비 Secondary large particles: weight ratio of secondary small particles 10:010:0 8:28:2 6:46:4 8:28:2 6:46:4 0:100:10
1 ㎛ 미만 비율 (%)Less than 1 μm ratio (%) 12.812.8 11.611.6 1616 6.76.7 2.12.1 6.26.2
상기 표 2의 실시예 1 및 비교예 3은 동일한 15㎛ 크기의 2차 대입자를 사용하되, 실시예 1의 경우 1차 거대 입자를 포함하는 2차 소입자를 바이모달로 사용한 경우이며, 비교예 3은 종래 1차 미세 입자를 포함하는 2차 입자 소입자를 바이모달로 사용한 경우이다. 표 2에서 알 수 있는 바와 같이, 압연시 1 ㎛ 미만의 미분은 비교예 3에 비해 실시예 1이 현저히 낮다. Examples 1 and 3 of Table 2 use the same large secondary particles of 15 μm in size, but in Example 1, secondary small particles including primary large particles were used in a bimodal manner, and Comparative Example 3 is a case in which secondary particle small particles including primary fine particles are used in a bimodal manner. As can be seen from Table 2, the fine powder of less than 1 μm during rolling is significantly lower in Example 1 than in Comparative Example 3.
표 2의 실시예 1 과 비교예 2는 각각 동일한 2차 대입자 및 2차 소입자를 사용한 경우이다. 다만, 실시예 1의 경우, 2차 대입자 : 2차 소입자의 중량비가 60 : 40이며, 비교예 2의 경우는, 80 : 20이다. 표 2에서 알 수 있는 바와 같이, 2차 소입자의 비율이 높아짐에 따라, 미분 형성 비율이 6.7%에서 2.1%로 현저히 낮아졌다. 반면, 비교예 1과 비교예 3을 비교하면, 실시예 1, 비교예 2와 동일한 비율로 제조하였으나, 1차 거대 입자를 포함하는 2차 소입자 대신에 종래 1차 미세 입자를 포함하는 2차 소입자를 바이모달로 사용한 경우이다. 표 2에서 알 수 있는 바와 같이, 종래 1차 미세 입자를 포함하는 2차 소입자의 비율이 높아짐에 따라, 미분 형성 비율이 11.6%에서 16%로 오히려 높아지는 것을 확인할 수 있었다. In Example 1 and Comparative Example 2 of Table 2, the same secondary large particles and secondary small particles were used, respectively. However, in the case of Example 1, the weight ratio of the secondary large particles: the secondary small particles is 60: 40, and in the case of Comparative Example 2, 80: 20. As can be seen from Table 2, as the ratio of secondary small particles increased, the fine powder formation ratio was significantly lowered from 6.7% to 2.1%. On the other hand, when Comparative Example 1 and Comparative Example 3 were compared, they were prepared in the same ratio as in Examples 1 and 2, but the secondary containing primary fine particles instead of the secondary small particles containing primary large particles. This is a case of using small particles as bimodal. As can be seen from Table 2, as the ratio of the secondary small particles including the conventional primary fine particles increased, it was confirmed that the fine powder formation ratio was rather increased from 11.6% to 16%.
한편, 비교예 10, 비교예 13과 같이 2차 대입자만을 단독으로 사용하거나, 1차 거대 입자를 포함하는 2차 소입자만을 단독으로 사용한 경우에는, 각각 미분 비율이 12.8%, 6.2%로 실시예 1에 비해 높게 형성되었다. On the other hand, when only the secondary large particles were used alone as in Comparative Examples 10 and 13, or when only the secondary small particles including the primary large particles were used alone, the fine powder ratio was 12.8% and 6.2%, respectively. It was formed higher than in Example 1.
비교예 11Comparative Example 11 비교예 4Comparative Example 4 비교예 6Comparative Example 6 비교예 5Comparative Example 5 실시예 2Example 2 비교예 13Comparative Example 13
2차 대입자 : 2차소입자의 중량비 Secondary large particles: weight ratio of secondary small particles 10:010:0 8:28:2 6:46:4 8:28:2 6:46:4 0:100:10
1 ㎛ 미만 비율 (%)Less than 1 μm ratio (%) 13.613.6 12.512.5 14.114.1 8.28.2 3.53.5 6.26.2
상기 표 3의 실시예 2 및 비교예 6은 동일한 10㎛ 크기의 2차 대입자를 사용하되, 실시예 2의 경우 1차 거대 입자를 포함하는 2차 소입자를 바이모달로 사용한 경우이며, 비교예 6은 종래 1차 미세 입자를 포함하는 2차 입자 소입자를 바이모달로 사용한 경우이다. 표 3에서 알 수 있는 바와 같이, 압연시 1 ㎛ 미만의 미분은 비교예 6에 비해 실시예 2이 현저히 낮다. Example 2 and Comparative Example 6 of Table 3 use the same large secondary particles of 10 μm in size, but in Example 2, secondary small particles including primary large particles were used in a bimodal manner, and Comparative Example 6 is a case in which secondary particle small particles including primary fine particles are used in a bimodal manner. As can be seen from Table 3, the fine powder of less than 1 μm during rolling is significantly lower in Example 2 than in Comparative Example 6.
표 3의 실시예 2 과 비교예 5는 각각 동일한 2차 대입자 및 2차 소입자를 사용한 경우이다. 다만, 실시예 2의 경우, 2차 대입자 : 2차 소입자의 중량비가 60 : 40이며, 비교예 5의 경우는, 80 : 20이다. 표 3에서 알 수 있는 바와 같이, 2차 소입자의 비율이 높아짐에 따라, 미분 형성 비율이 8.2%에서 3.5%로 현저히 낮아졌다. 반면, 비교예 4과 비교예 6을 비교하면, 비교예 5, 실시예 2와 동일한 비율로 제조하였으나, 1차 거대 입자를 포함하는 2차 소입자 대신에 종래 1차 미세 입자를 포함하는 2차 소입자를 바이모달로 사용한 경우이다. 표 3에서 알 수 있는 바와 같이, 종래 1차 미세 입자를 포함하는 2차 소입자의 비율이 높아짐에 따라, 미분 형성 비율이 12.5%에서 14.1%로 오히려 높아지는 것을 확인할 수 있었다. In Example 2 and Comparative Example 5 of Table 3, the same secondary large particles and secondary small particles were used, respectively. However, in the case of Example 2, the weight ratio of the secondary large particles: the secondary small particles is 60:40, and in the case of Comparative Example 5, 80:20. As can be seen from Table 3, as the ratio of secondary small particles increased, the fine powder formation ratio was significantly lowered from 8.2% to 3.5%. On the other hand, comparing Comparative Example 4 and Comparative Example 6, Comparative Examples 5 and 2 were prepared in the same ratio as in Example 2, but instead of the secondary small particles including the primary large particles, the secondary containing the conventional primary fine particles This is a case of using small particles as bimodal. As can be seen from Table 3, as the ratio of the secondary small particles including the conventional primary fine particles increased, it was confirmed that the fine powder formation ratio was rather increased from 12.5% to 14.1%.
한편, 비교예 11, 비교예 13과 같이 2차 대입자만을 단독으로 사용하거나, 1차 거대 입자를 포함하는 2차 소입자만을 단독으로 사용한 경우에는, 각각 미분 비율이 13.6%, 6.2%로 실시예 2에 비해 높게 형성되었다. On the other hand, when only the secondary large particles were used alone as in Comparative Examples 11 and 13, or when only the secondary small particles including the primary large particles were used alone, the fine powder ratio was 13.6% and 6.2%, respectively. It was formed higher than in Example 2.
비교예 12Comparative Example 12 비교예 7Comparative Example 7 비교예 9Comparative Example 9 비교예 8Comparative Example 8 비교예 13Comparative Example 13
2차 대입자 : 2차소입자의 중량비 Secondary large particles: weight ratio of secondary small particles 10:010:0 8:28:2 6:46:4 8:28:2 0:100:10
1 ㎛ 미만 비율 (%)Less than 1 μm ratio (%) 15.115.1 13.913.9 15.015.0 9.19.1 6.26.2
상기 표 4의 비교예 9은 8㎛ 크기의 2차 대입자를 사용하되, 종래 1차 미세 입자를 포함하는 2차 입자 소입자를 바이모달로 사용한 경우이다. 비교예 9과 비교예 7을 비교하면, 비교예 8와 동일한 비율로 제조하였으나, 1차 거대 입자를 포함하는 2차 소입자 대신에 종래 1차 미세 입자를 포함하는 2차 소입자를 바이모달로 사용한 경우이다. 표 4에서 알 수 있는 바와 같이, 종래 1차 미세 입자를 포함하는 2차 소입자의 비율이 높아짐에 따라, 미분 형성 비율이 13.9%에서 15.0%로 오히려 높아지는 것을 확인할 수 있었다. Comparative Example 9 of Table 4 uses large secondary particles having a size of 8 μm, but is a case in which small secondary particles including primary fine particles are used in a bimodal manner. Comparing Comparative Example 9 and Comparative Example 7, although prepared in the same ratio as in Comparative Example 8, the secondary small particles containing the conventional primary fine particles were bimodal instead of the secondary small particles containing the primary large particles. in case it was used. As can be seen from Table 4, as the ratio of the secondary small particles including the conventional primary fine particles increased, it was confirmed that the fine powder formation ratio was rather increased from 13.9% to 15.0%.
한편, 비교예 7 내지 9은 2차 대입자만을 단독으로 사용한 비교예 12 대비 낮은 미분 비율을 나타내었지만, 비교예 13와 같이 1차 거대 입자를 포함하는 2차 소입자만을 단독으로 사용한 경우 대비 높은 미분을 나타냈다.On the other hand, Comparative Examples 7 to 9 showed a lower fine powder ratio compared to Comparative Example 12 in which only the secondary large particles were used alone, but as in Comparative Example 13, higher than when only the secondary small particles including the primary large particles were used alone showed differential.
[실험예 2: 조성에 따른 양극 압연 전후 2차 대입자 피크 강도 변화][Experimental Example 2: Secondary Large Particle Peak Intensity Change Before and After Anode Rolling According to Composition]
2차 대입자의 피크 강도(peak intensity)는 다음과 같은 방법으로 측정하였다. The peak intensity of the secondary large particles was measured as follows.
실험예 1과 같이 압연을 가한 양극 활물질과 압연 공정을 거치지 않은 상태의 양극 활물질에 대하여 PSD를 측정하고 압연 전후의 결과를 비교하였다. 이 때 측정된 압연 전 대입자 피크 강도 - 압연 후 대입자 피크 강도를 감소율(%)로 하기 표 5 내지 7에 나타내었다. As in Experimental Example 1, PSD was measured for the positive active material to which rolling was applied and the positive active material to which the rolling process was not performed, and the results before and after rolling were compared. At this time, the measured peak intensity of the large particle before rolling - the peak intensity of the large particle after rolling, as a reduction rate (%), is shown in Tables 5 to 7 below.
비교예 1Comparative Example 1 비교예 3Comparative Example 3 비교예 2Comparative Example 2 실시예 1Example 1
2차 대입자 : 2차소입자의 중량비 Secondary large particles: weight ratio of secondary small particles 8:28:2 6:46:4 8:28:2 6:46:4
대입자 peak 강도감소 (%)
Before - AfterLarge particle peak intensity decrease (%)
Before - After 		33 1.11.1 1.81.8 00
표 5의 비교예 1 내지 3, 실시예 1은 모두 15㎛ 크기의 2차 대입자와 2차 소입자를 바이모달로 사용한 경우이다. 다만, 비교예 1, 3의 경우는 2차 입자 소입자를 사용하였으며, 2차 입자 소입자를 구성하는 1차 입자가, 직경이 0.5 ㎛ 이하인 1차 미세 입자인 것이다. 반면, 비교예 2, 실시예 1의 경우는, 직경이 1㎛ 이상인 1차 거대 입자가 10개 이내로 응집되어 있는 2차 소입자를 사용한 경우이다. Comparative Examples 1 to 3 and Example 1 of Table 5 are all cases in which secondary large particles and secondary small particles having a size of 15 μm were used in a bimodal manner. However, in Comparative Examples 1 and 3, small secondary particles were used, and the primary particles constituting the secondary particles were primary fine particles having a diameter of 0.5 μm or less. On the other hand, in Comparative Examples 2 and 1, secondary small particles in which 10 or less primary large particles having a diameter of 1 μm or more were aggregated were used.
표 5에서 알 수 있는 바와 같이, 비교예 1에서 비교예 3으로 2차 입자 소입자의 비율이 높아짐에 따라 대입자의 피크 감소율이 3%에서 1.1%로 감소하였다. 실험예 1에서 1㎛ 미만 미분 함량이 증가하던 경향과는 다른 방향인데, 이는 전체적으로 대입자의 비율이 감소한 변화가 영향을 미친 것으로 판단된다. 또한, 비교예 2에서 실시예 1로 2차 소입자의 비율이 높아짐에 따라 대입자의 피크 감소율이 1.8%에서 0%로 감소하였다. 이는 비교예 1에서 비교예 3으로의 변화와 마찬가지로 대입자의 비율이 감소한 변화가 영향을 미치겠지만 실험예 1에서 1㎛ 미만 미분 함량이 감소한 결과와 같은 경향을 나타내고 있다. 이러한 결과들을 바탕으로 1차 거대 입자를 사용한 실시예 1의 경우가 변화율이 더 작게 나타나고 2차 대입자의 형상이 보다 잘 유지됨을 추정할 수 있다. As can be seen from Table 5, as the ratio of secondary particles small particles increased from Comparative Example 1 to Comparative Example 3, the peak decrease rate of large particles decreased from 3% to 1.1%. In Experimental Example 1, it is in a different direction from the trend in which the content of fines less than 1 μm increased, which is judged to be influenced by the change in the ratio of large particles as a whole. In addition, as the ratio of secondary small particles increased from Comparative Example 2 to Example 1, the peak decrease rate of large particles decreased from 1.8% to 0%. Similar to the change from Comparative Example 1 to Comparative Example 3, a change in the ratio of large particles has an effect, but shows the same trend as the result of a decrease in the fine powder content of less than 1 μm in Experimental Example 1. Based on these results, it can be estimated that the change rate of Example 1 using the primary large particles is smaller and the shape of the secondary large particles is better maintained.
비교예 4Comparative Example 4 비교예 6Comparative Example 6 비교예 5Comparative Example 5 실시예 2Example 2
2차 대입자 : 2차소입자의 중량비 Secondary large particles: weight ratio of secondary small particles 8:28:2 6:46:4 8:28:2 6:46:4
대입자 peak 강도감소 (%)
Before - AfterLarge particle peak intensity decrease (%)
Before - After 		5.55.5 1.91.9 3.73.7 1.71.7
표 6의 비교예 4 내지 6, 실시예 2은 모두 10㎛ 크기의 2차 대입자와 2차 소입자를 바이모달로 사용한 경우이다. 다만, 비교예 4, 6의 경우는 2차 입자 소입자를 사용하였으며, 2차 입자 소입자를 구성하는 1차 입자가, 직경이 0.5 ㎛ 이하인 1차 미세 입자인 것이다. 반면, 비교예 5, 실시예 2의 경우는, 직경이 1㎛ 이상인 1차 거대 입자가 응집되어 있는 2차 소입자를 사용한 경우이다. Comparative Examples 4 to 6 and Example 2 of Table 6 are cases in which secondary large particles and secondary small particles having a size of 10 μm are used in a bimodal manner. However, in Comparative Examples 4 and 6, small secondary particles were used, and the primary particles constituting the secondary particles were primary fine particles having a diameter of 0.5 μm or less. On the other hand, in Comparative Examples 5 and 2, secondary small particles in which primary large particles having a diameter of 1 μm or more are aggregated are used.
표 6에서 알 수 있는 바와 같이, 비교예 4에서 비교예 6으로 2차 입자 소입자의 비율이 높아짐에 따라 대입자의 피크 감소율이 5.5%에서 1.9%로 감소하였다. 실험예 1에서 1㎛ 미만 미분 함량이 증가하던 경향과는 다른 방향인데, 이는 전체적으로 대입자의 비율이 감소한 변화가 영향을 미친 것으로 판단된다. 또한, 비교예 5에서 실시예 2로 2차 소입자의 비율이 높아짐에 따라 대입자의 피크 감소율이 3.7%에서 1.7%로 감소하였다. 이는 비교예 4에서 비교예 6으로의 변화와 마찬가지로 대입자의 비율이 감소한 변화가 영향을 미치겠지만 실험예 1에서 1㎛ 미만 미분 함량이 감소한 결과와 같은 경향을 나타내고 있다. 이러한 결과들을 바탕으로 1차 거대 입자를 사용한 실시예 2의 경우가 변화율이 더 작게 나타나고 2차 대입자의 형상이 보다 잘 유지됨을 추정할 수 있다. As can be seen from Table 6, as the ratio of secondary particles small particles increased from Comparative Example 4 to Comparative Example 6, the peak decrease rate of large particles decreased from 5.5% to 1.9%. In Experimental Example 1, it is in a different direction from the trend in which the content of fines less than 1 μm increased, which is judged to be influenced by the change in the ratio of large particles as a whole. In addition, as the ratio of secondary small particles increased from Comparative Example 5 to Example 2, the peak decrease rate of large particles decreased from 3.7% to 1.7%. Similar to the change from Comparative Example 4 to Comparative Example 6, a change in the ratio of large particles has an effect, but shows the same trend as the result of a decrease in the fine powder content of less than 1 μm in Experimental Example 1. Based on these results, it can be estimated that the change rate of Example 2 using the primary large particles is smaller and the shape of the secondary large particles is better maintained.
비교예 7Comparative Example 7 비교예 9Comparative Example 9 비교예 8Comparative Example 8
2차 대입자 : 2차소입자의 중량비 Secondary large particles: weight ratio of secondary small particles 8:28:2 6:46:4 8:28:2
대입자 peak 강도감소 (%)
Before - AfterLarge particle peak intensity decrease (%)
Before - After 		6.16.1 3.33.3 4.24.2
표 7의 비교예 7 내지 9은 모두 2차 8㎛ 크기의 2차 대입자와 2차 소입자를 바이모달로 사용한 경우이다. 다만, 비교예 7, 9의 경우는 2차 입자 소입자를 사용하였으며, 2차 입자 소입자를 구성하는 1차 입자가, 직경이 0.5 ㎛ 이하인 1차 미세 입자인 것이다. 반면, 비교예 8의 경우는, 직경이 1㎛ 이상인 1차 거대 입자가 10개 이내로 응집되어 있는 2차 소입자를 사용한 경우이다.In Comparative Examples 7 to 9 of Table 7, all of the secondary large particles and secondary small particles having a size of 8 μm were used in a bimodal manner. However, in Comparative Examples 7 and 9, small secondary particles were used, and the primary particles constituting the secondary particles were primary fine particles having a diameter of 0.5 μm or less. On the other hand, in Comparative Example 8, secondary small particles in which 10 or less primary large particles having a diameter of 1 μm or more were aggregated were used.
표 7에서 알 수 있는 바와 같이, 비교예 7에서 비교예 9으로 2차 입자 소입자의 비율이 높아짐에 따라 대입자의 피크 감소율이 6.1%에서 3.3%로 감소하였다. 실험예 1에서 1㎛ 미만 미분 함량이 증가하던 경향과는 다른 방향인데, 이는 전체적으로 대입자의 비율이 감소한 변화가 영향을 미친 것으로 판단된다. 또한, 비교예 8에서 비교예 9로 2차 소입자의 비율이 높아짐에 따라 대입자의 피크 감소율이 4.2%에서 2.5%로 감소하였다. 이는 비교예 7에서 비교예 9으로의 변화와 마찬가지로 대입자의 비율이 감소한 변화가 영향을 미치겠지만 실험예 1에서 1㎛ 미만 미분 함량은 증가하여, 두 실험의 경향이 반대를 나타내고 있다. As can be seen from Table 7, as the ratio of secondary particles small particles increased from Comparative Example 7 to Comparative Example 9, the peak decrease rate of large particles decreased from 6.1% to 3.3%. In Experimental Example 1, it is in a different direction from the trend in which the content of fines less than 1 μm increased, which is judged to be influenced by the change in the ratio of large particles as a whole. In addition, as the ratio of secondary small particles increased from Comparative Example 8 to Comparative Example 9, the peak decrease rate of large particles decreased from 4.2% to 2.5%. Similar to the change from Comparative Example 7 to Comparative Example 9, a change in the ratio of large particles had an effect, but in Experimental Example 1, the fine powder content of less than 1 μm increased, indicating the opposite trend of the two experiments.
이러한 결과들을 바탕으로 2차 대입자와 1차 거대 입자가 응집되어 있는 2차 소입자와 혼합 적용시 입자 깨짐 개선 효과적으로 나타내기 위해서는 8㎛ 크기의 2차 대입자보다 10㎛, 15㎛ 크기의 2차 대입자로 갈수록 효과가 큰 것을 추정할 수 있다. Based on these results, in order to effectively show particle breakage improvement when mixed and applied with secondary small particles in which secondary large particles and primary large particles are aggregated, 2 particles of 10 μm and 15 μm in size are more effective than secondary large particles of 8 μm in size. It can be estimated that the effect increases as the borrower becomes a borrower.
[실험예 3: 조성에 따른 30회 충방전지 잔존 용량 비교][Experimental Example 3: Comparison of Residual Capacity of 30 Charge/Discharge Battery According to Composition]
실시예 1과 2, 비교예 1, 2, 3, 5, 8, 13에 따른 양극 활물질을 이용하여 다음과 같은 방법으로 용량 유지율을 측정하였다. Using the cathode active materials according to Examples 1 and 2 and Comparative Examples 1, 2, 3, 5, 8, and 13, capacity retention was measured in the following manner.
실시예 및 비교예에서 제조된 각각의 양극 활물질, 카본블랙 도전재 및 PVdF 바인더를 N-메틸피롤리돈 용매 중에서 중량비로 96:2:2의 비율로 혼합하여 양극 슬러리를 제조하고, 이를 알루미늄 집전체의 일면에 도포한 후, 100 ℃에서 건조 후, 압연하여 양극을 제조하였다.Each of the positive electrode active material, carbon black conductive material, and PVdF binder prepared in Examples and Comparative Examples was mixed in an N-methylpyrrolidone solvent in a weight ratio of 96:2:2 to prepare a positive electrode slurry, which After coating on the entire surface, drying at 100 °C, and rolling to prepare a positive electrode.
음극은 리튬 메탈을 사용하였다.As the negative electrode, lithium metal was used.
상기와 같이 제조된 양극과 음극 사이에 다공성 폴리에틸렌의 세퍼레이터를 개재하여 전극 조립체를 제조하고, 상기 전극 조립체를 케이스 내부에 위치시킨 후, 케이스 내부로 전해액을 주입하여 리튬 이차 전지를 제조하였다. 이때 전해액은 에틸렌카보네이트/에틸메틸카보네이트/디에틸카보네이트/(EC/EMC/DEC의 혼합 부피비=3/4/3)로 이루어진 유기 용매에 1.0M 농도의 리튬헥사플루오로포스페이트(LiPF6)를 용해시켜 제조하였다.An electrode assembly was prepared by interposing a separator of porous polyethylene between the positive electrode and the negative electrode prepared as described above, the electrode assembly was placed inside the case, and the electrolyte was injected into the case to prepare a lithium secondary battery. At this time, the electrolyte solution is obtained by dissolving lithium hexafluorophosphate (LiPF6) at a concentration of 1.0M in an organic solvent consisting of ethylene carbonate/ethylmethyl carbonate/diethyl carbonate/(mixed volume ratio of EC/EMC/DEC=3/4/3). prepared.
제조된 리튬 이차전지 하프 셀(half cell)에 대해, 45℃에서 CC-CV모드로 0.7C로 4.4V가 될 때까지 충전하고, 0.5C의 정전류로 3.0V까지 방전하여 30회 충방전 실험을 진행하였을 시의 용량 유지율을 측정하여 수명 특성 평가를 진행하였다. 그 결과를 하기 표 8에 나타내었다.The prepared lithium secondary battery half cell was charged at 45°C in CC-CV mode at 0.7C to 4.4V, and discharged to 3.0V at a constant current of 0.5C to conduct 30 charge/discharge experiments. The capacity retention rate at the time of proceeding was measured to evaluate the lifespan characteristics. The results are shown in Table 8 below.
비교예 1Comparative Example 1 비교예 2Comparative Example 2 비교예 3Comparative Example 3 비교예 5Comparative Example 5 비교예 8Comparative Example 8 실시예 1Example 1 실시예 2Example 2 비교예 13Comparative Example 13
대입자 : 소입자의 중량비 Large particle: weight ratio of small particle 8:28:2 8:28:2 6:46:4 8:28:2 8:28:2 6:46:4 6:46:4 0:100:10
용량 유지율 (%)Capacity retention rate (%) 81.681.6 84.784.7 81.081.0 84.584.5 83.583.5 89.589.5 89.189.1 85.185.1
표 8에서 알 수 있는 바와 같이, 동일한 15㎛ 크기의 2차 대입자를 사용한 실시예 1과 비교예 1 내지 3에서, 1차 거대 입자를 포함하는 2차 소입자와, 기존의 2차 대입자를 40 : 60의 비율로 사용한 실시예 1의 경우가 가장 높은 용량 유지율을 나타내었다. 이러한 경향은 10㎛ 크기의 2차 대입자를 적용한 실시예 2와 비교예 5, 8㎛ 크기의 2차 대입자를 적용한 비교예 8에서도 동일하게 확인된다. As can be seen from Table 8, in Example 1 and Comparative Examples 1 to 3 using the same large secondary particles of 15 μm in size, the secondary small particles including the primary large particles and the existing secondary large particles were 40 Example 1 used in a ratio of : 60 showed the highest capacity retention rate. This tendency is also confirmed in Example 2 and Comparative Example 5 to which secondary large particles of 10 μm in size are applied, and Comparative Example 8 in which secondary large particles of 8 μm in size are applied.
[실험예 4: 2차 대입자 평균 입경 크기에 따른 양극 압연시 대입자 peak count 감소 비교][Experimental Example 4: Comparison of large particle peak count reduction during anode rolling according to the average particle size of secondary large particles]
대입자의 피크 카운트를 다음과 같은 방법으로 산정하였다:The peak counts of large particles were calculated as follows:
실험예 1과 같이 압연을 가한 양극 활물질과 압연 공정을 거치지 않은 상태의 양극재에 대하여 PSD를 측정하고 압연 전후의 결과를 비교하였다. 이때 측정된 압연 전 대입자 피크 강도 - 압연 후 대입자 피크 강도를 감소율(%)로 하기 표 9에 나타내었다.As in Experimental Example 1, PSD was measured for the positive electrode active material to which rolling was applied and the positive electrode material to which the rolling process was not performed, and the results before and after rolling were compared. At this time, the measured peak strength of large particles before rolling - The peak strength of large particles after rolling was shown in Table 9 below as a reduction rate (%).
2차 대입자 + 2차 소입자 Secondary large particle + secondary small particle
구분division 실시예 1Example 1 실시예 2Example 2
대입자 peak 강도감소 (%)
Before - AfterLarge particle peak intensity decrease (%)
Before - After 		00 1.71.7
표 9에서 알 수 있는 바와 같이, 2차 대입자와 2차 소입자를 동일한 함량으로 사용하더라도, 실시예 2의 경우와 같이 대입자의 평균 입경(D50)이 15㎛ 에서 10 ㎛로 감소하게 되면 2차 대입자의 입자 깨짐이 더 심해지는 것을 확인할 수 있었다. As can be seen from Table 9, even when the secondary large particles and the secondary small particles are used in the same content, as in Example 2, when the average particle diameter (D50) of the large particles decreases from 15 μm to 10 μm, 2 It was confirmed that the particle breakage of the car loaner became more severe.

Claims (15)

  1. 대입자의 제1 양극 활물질 및 소입자의 제2 양극 활물질을 포함하는 리튬 이차 전지용 양극 활물질이며, It is a positive electrode active material for a lithium secondary battery comprising a first positive electrode active material of large particles and a second positive electrode active material of small particles,
    상기 제1 양극 활물질은, 1차 미세(micro) 입자의 응집체를 포함하는 적어도 하나의 2차 대입자를 포함하며,The first positive active material includes at least one secondary large particle including an aggregate of primary micro particles,
    상기 제2 양극 활물질은, 1차 거대(macro) 입자의 응집체를 포함하는 적어도 하나의 2차 소입자를 포함하며, The second positive active material includes at least one secondary small particle including an aggregate of primary macro particles,
    상기 1차 거대 입자의 평균 입경(D50)은 1 ㎛ 이상이며,The average particle diameter (D50) of the primary large particles is 1 μm or more,
    상기 제1 양극 활물질의 평균 입경(D50)/상기 제2 양극 활물질의 평균 입경(D50)의 비는 2 이상이며, The ratio of the average particle diameter (D50) of the first positive active material / the average particle diameter (D50) of the second positive active material is 2 or more,
    상기 제1 양극 활물질과 상기 제2 양극 활물질의 중량비는 50 : 50 내지 70 : 30인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질. A positive active material for a lithium secondary battery, characterized in that the weight ratio of the first positive active material to the second positive active material is 50:50 to 70:30.
  2. 제1항에 있어서, According to claim 1,
    상기 1차 거대 입자의 평균 직경(D50)은 2 ㎛ 이상이며, The average diameter (D50) of the primary large particles is 2 μm or more,
    상기 1차 거대 입자의 평균 입경(D50)/상기 1차 거대 입자의 평균 결정 크기(crystal size)의 비는 2 이상인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질. The positive active material for a lithium secondary battery, characterized in that the ratio of the average particle diameter (D50) of the primary large particles to the average crystal size of the primary large particles is 2 or more.
  3. 제1항에 있어서, According to claim 1,
    상기 제1 양극 활물질의 평균 입경(D50)은 10 ㎛ 내지 20 ㎛ 인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질. The positive electrode active material for a lithium secondary battery, characterized in that the average particle diameter (D50) of the first positive active material is 10 μm to 20 μm.
  4. 제1항에 있어서, According to claim 1,
    상기 제2 양극 활물질의 평균 입경(D50)은 3 ㎛ 내지 6 ㎛ 인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질. The second positive electrode active material has an average particle diameter (D50) of 3 μm to 6 μm.
  5. 제1항에 있어서, According to claim 1,
    상기 제1 양극 활물질의 1차 미세 입자의 평균 입경(D50)은 0.1 ㎛ 내지 0.5 ㎛ 인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질. The average particle diameter (D50) of the primary fine particles of the first positive electrode active material is a positive electrode active material for a lithium secondary battery, characterized in that 0.1 μm to 0.5 μm.
  6. 제1항에 있어서, According to claim 1,
    상기 제2 양극 활물질은, 상기 2차 소입자를 압연시 상기 1차 거대 입자가 떨어져 나가며, 상기 1차 거대 입자 자체는 깨지지 않는 것을 특징으로 하는 리튬 이차 전지용 양극 활물질. The second positive active material is a positive electrode active material for a lithium secondary battery, characterized in that the primary large particles fall off when the secondary small particles are rolled, and the primary large particles themselves are not broken.
  7. 제6항에 있어서, 7. The method of claim 6,
    상기 압연은 상기 양극 활물질을 포함하는 양극의 기공도가 15 내지 30%가 되도록 수행되는 것을 특징으로 하는 리튬 이차 전지용 양극 활물질. The rolling is a positive electrode active material for a lithium secondary battery, characterized in that the porosity of the positive electrode including the positive electrode active material is 15 to 30%.
  8. 제1항에 있어서, According to claim 1,
    상기 1차 거대 입자의 평균 결정 크기는 150 nm 이상인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질. The positive active material for a lithium secondary battery, characterized in that the average crystal size of the primary large particles is 150 nm or more.
  9. 제1항에 있어서, According to claim 1,
    상기 2차 소입자의 평균 입경(D50)/상기 1차 거대 입자의 평균 입경(D50)의 비는 2 내지 4배인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질. A cathode active material for a lithium secondary battery, characterized in that the ratio of the average particle diameter (D50) of the secondary small particles to the average particle diameter (D50) of the primary large particles is 2 to 4 times.
  10. 제1항에 있어서, According to claim 1,
    상기 제1 및 제2 양극 활물질은 니켈계 리튬 전이금속 산화물을 포함하는 것을 특징으로 하는 리튬 이차 전지용 양극 활물질. The first and second positive electrode active materials are a positive electrode active material for a lithium secondary battery, characterized in that it comprises a nickel-based lithium transition metal oxide.
  11. 제10항에 있어서, 11. The method of claim 10,
    상기 니켈계 리튬 전이금속 산화물은, Li(1+a)Ni(1-(a+x+y+w))CoxM1yM2wO2 (여기에서, 0≤a≤0.5, 0≤x≤0.35, 0≤y≤0.35, 0≤w≤0.1, 0≤a+x+y+w≤0.7, M1은 Mn 및 Al으로 이루어지는 군으로부터 선택되는 적어도 1종, M2는 Ba, Ca, Zr, Ti, Mg, Ta, Nb 및 Mo으로 이루어지는 군으로부터 선택되는 적어도 1종)을 포함하는 것을 특징으로 하는 리튬 이차 전지용 양극 활물질. The nickel-based lithium transition metal oxide is, Li (1+a) Ni (1-(a+x+y+w)) Co x M1 y M2 w O 2 (here, 0≤a≤0.5, 0≤x ≤0.35, 0≤y≤0.35, 0≤w≤0.1, 0≤a+x+y+w≤0.7, M1 is at least one selected from the group consisting of Mn and Al, M2 is Ba, Ca, Zr, At least one selected from the group consisting of Ti, Mg, Ta, Nb and Mo), a positive active material for a lithium secondary battery comprising:
  12. 제1항에 있어서, According to claim 1,
    상기 양극 활물질은 상기 양극 활물질을 포함하는 양극의 기공도가 15 내지 30%인 조건에서, PSD 분포에서, 1 ㎛ 미만의 입자 비율이 10% 미만인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질.The positive active material is a positive active material for a lithium secondary battery, characterized in that the ratio of particles less than 1 μm in PSD distribution under the condition that the porosity of the positive electrode including the positive active material is 15 to 30% is less than 10%.
  13. 제1항에 있어서, According to claim 1,
    상기 양극 활물질은, 상기 양극 활물질을 포함하는 양극의 기공도가 15 내지 30%이 되도록 가압할 때, 가압 전/후, 상기 2차 대입자의 피크 강도(peak intensity) 감소율이 2% 미만인 것을 특징으로 하는 리튬 이차 전지용 양극 활물질.When the positive electrode active material is pressurized so that the porosity of the positive electrode including the positive active material is 15 to 30%, the peak intensity decrease rate of the secondary large particles before and after the pressurization is less than 2%, characterized in that A cathode active material for a lithium secondary battery.
  14. 제1항에 따른 양극 활물질을 포함하는 리튬 이차 전지용 양극. A positive electrode for a lithium secondary battery comprising the positive active material according to claim 1 .
  15. 제1항에 따른 양극 활물질을 포함하는 리튬 이차 전지. A lithium secondary battery comprising the positive active material according to claim 1 .
PCT/KR2021/015952 2020-11-05 2021-11-04 Positive electrode active material for lithium secondary battery, and lithium secondary battery comprising same WO2022098135A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103872311A (en) * 2012-12-12 2014-06-18 三星Sdi株式会社 Positive active material, positive electrode and rechargeable lithium battery including same
KR20190093454A (en) * 2018-02-01 2019-08-09 주식회사 엘지화학 Positive electrode active material for secondary battery, method for preparing the same and lithium secondary battery comprising the same
KR20190093453A (en) * 2018-02-01 2019-08-09 주식회사 엘지화학 Positive electrode active material for secondary battery, method for preparing the same and lithium secondary battery comprising the same
KR20190133456A (en) * 2018-05-23 2019-12-03 주식회사 엘지화학 Positive electrode material for lithium secondary battery, positive electrode for lithium secondary battery and lithium secondary battery comprising the same
KR20200030287A (en) * 2018-09-12 2020-03-20 주식회사 엘지화학 Positive electrode material for secondary battery, method for preparing the same and lithium secondary battery comprising the same

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103872311A (en) * 2012-12-12 2014-06-18 三星Sdi株式会社 Positive active material, positive electrode and rechargeable lithium battery including same
KR20190093454A (en) * 2018-02-01 2019-08-09 주식회사 엘지화학 Positive electrode active material for secondary battery, method for preparing the same and lithium secondary battery comprising the same
KR20190093453A (en) * 2018-02-01 2019-08-09 주식회사 엘지화학 Positive electrode active material for secondary battery, method for preparing the same and lithium secondary battery comprising the same
KR20190133456A (en) * 2018-05-23 2019-12-03 주식회사 엘지화학 Positive electrode material for lithium secondary battery, positive electrode for lithium secondary battery and lithium secondary battery comprising the same
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