WO2019059654A1 - Cathode active material precursor for secondary battery, cathode active material, and lithium secondary battery comprising same - Google Patents

Cathode active material precursor for secondary battery, cathode active material, and lithium secondary battery comprising same Download PDF

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Publication number
WO2019059654A1
WO2019059654A1 PCT/KR2018/011081 KR2018011081W WO2019059654A1 WO 2019059654 A1 WO2019059654 A1 WO 2019059654A1 KR 2018011081 W KR2018011081 W KR 2018011081W WO 2019059654 A1 WO2019059654 A1 WO 2019059654A1
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WIPO (PCT)
Prior art keywords
active material
doping element
precursor
cathode active
lithium
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PCT/KR2018/011081
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French (fr)
Korean (ko)
Inventor
유민규
조치호
박성빈
허혁
황진태
정왕모
Original Assignee
주식회사 엘지화학
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Publication date
Priority claimed from KR1020180111642A external-priority patent/KR102217105B1/en
Application filed by 주식회사 엘지화학 filed Critical 주식회사 엘지화학
Priority to EP18857652.4A priority Critical patent/EP3560894A4/en
Priority to CN201880008449.9A priority patent/CN110225886A/en
Priority to JP2020516365A priority patent/JP7047203B2/en
Priority to US16/480,832 priority patent/US11611076B2/en
Publication of WO2019059654A1 publication Critical patent/WO2019059654A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G51/00—Compounds of cobalt
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G51/00—Compounds of cobalt
    • C01G51/04—Oxides; Hydroxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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 precursor for a secondary battery, a cathode active material, and a lithium secondary battery comprising the same.
  • the lithium secondary battery includes a cathode including a cathode active material capable of intercalating / deintercalating lithium ions, a cathode including a cathode active material capable of intercalating / deintercalating lithium ions, an electrode including a microporous separator interposed between the cathode and the anode, Means a battery in which an electrolyte containing lithium ions is contained in an assembly.
  • a lithium transition metal oxide is used as the positive electrode active material of the lithium secondary battery, and lithium metal, lithium alloy, crystalline or amorphous carbon or carbon composite is used as the negative electrode active material.
  • the active material is coated on the electrode current collector with an appropriate thickness and length, or the active material itself is coated in a film form and wrapped or laminated with a separator as an insulator to form an electrode group. The electrode group is then placed in a can or similar container, Thereby manufacturing a secondary battery.
  • Lithium cobalt oxide (LiCoO 2 ) has a layered structure as a cathode active material of a lithium secondary battery that has been actively researched and used at present.
  • Lithium cobalt oxide (LiCoO 2 ) has an advantage of high operating voltage and excellent capacity characteristics, but its thermal characteristics are poor due to the destabilization of the crystal structure due to lithium remnants and the structure becomes unstable under high voltage.
  • lithium cobalt oxide (LiCoO 2 ) has been increasingly required for a high capacity lithium secondary battery. Unlike a tin oxide cathode active material, the capacity can be increased only by raising the voltage. Therefore, It is necessary to develop lithium cobalt oxide (LiCoO 2 ) capable of securing the structural stability even at 4.5 V or more.
  • An object of the present invention is to provide a cathode active material of lithium cobalt oxide which is an acceptor having an average particle diameter (D 50 ) of 15 ⁇ m or more by solving the problem of obstructing grain growth by a doping element while having structural stability under high voltage by excessively doping a doping element will be.
  • the present invention relates to a secondary battery comprising a primary particle of Co 3 O 4 or CoOOH, wherein the primary particle contains 3,000 ppm or more of a doping element and the average particle diameter (D 50 ) of the primary particle is 15 ⁇ m or more Precursor.
  • the present invention also provides a lithium secondary battery comprising a primary particle of a lithium cobalt oxide, wherein the primary particle contains a doping element in an amount of 2,500 ppm or more, and the primary particle has an average particle diameter (D 50 ) .
  • the present invention also provides a method of forming a precursor, comprising: providing a precursor forming solution comprising a cobalt-containing starting material and a doping element source; And forming a precursor of Co 3 O 4 or CoOOH having an average particle diameter (D 50 ) of the primary particles of not less than 15 ⁇ m and containing the doping element in an amount of 3,000 ppm or more by coprecipitation reaction with the precursor forming solution, A method for manufacturing a positive electrode active material precursor for a battery is provided.
  • the cathode active material precursor powder and the lithium source according to the present invention are mixed and sintered to prepare a lithium cobalt oxide having an average particle size (D 50 ) of the primary particles of not less than 2,500 ppm and having a primary particle size of not less than 15 ⁇ m
  • the present invention also provides a method for producing a cathode active material for a secondary battery.
  • the present invention also provides a positive electrode and a lithium secondary battery including the positive electrode active material.
  • a cathode active material of lithium cobalt oxide which is an acceptor having an average particle diameter (D 50 ) of 15 ⁇ m or more, by solving the problem of obstructing grain growth by a doping element while having structural stability under high voltage by excessively doping the doping element can do.
  • Example 1 is a scanning electron microscope (SEM) photograph of a precursor of a cathode active material prepared according to Example 1 of the present invention.
  • a precursor is doped with an excessive amount of a doping element, and a precursor particle size is increased up to an average particle diameter (D 50 ) of 15 ⁇ m or more to prepare a precursor of an acceptor.
  • D 50 average particle diameter
  • the cathode active material precursor for a secondary battery according to the present invention comprises primary particles of Co 3 O 4 or CoOOH, wherein the primary particles contain 3,000 ppm or more of a doping element, and the average particle diameter of the primary particles (D 50 ) Is not smaller than 15 mu m.
  • the cathode active material precursor of the present invention is composed of primary particles of Co 3 O 4 or CoOOH.
  • the positive electrode active material precursor of the present invention is preferably a primary particle that is not a secondary particle formed by aggregation of primary particles but is not physically separated.
  • the average particle diameter (D 50 ) of the primary particles is 15 ⁇ m or more, and more preferably the average particle diameter (D 50 ) of the primary particles is 17 ⁇ m or more.
  • the average particle diameter (D 50 ) of the primary particles of the cathode active material precursor is less than 15 ⁇ , when the cathode active material is produced through a firing process using a precursor of less than 15 ⁇ , the doping element interferes with the particle growth, There arises a problem that it is difficult to produce a cathode active material having a thickness (D 50 ) of 15 ⁇ m or more. If the positive electrode active material can not be made into an average particle diameter (D 50 ) of 15 ⁇ m or more, there is a limit to increase the compression density of the positive electrode and it is difficult to increase the battery capacity.
  • the cathode active material precursor of the present invention may contain not less than 3,000 ppm of the doping element and more preferably not less than 4,000 ppm of the doping element.
  • the primary particles of the cathode active material precursor may contain less than 3,000 ppm of the doping element, it is difficult to secure the structural stability of the lithium cobalt oxide cathode active material.
  • the primary particles of the cathode active material precursor have low structural stability at a high voltage of 4.5 V or higher, There may be a problem of deterioration of battery characteristics.
  • a doping element is further added to the precursor when the undoped precursor is formed as a substituent, Doping element having a uniform concentration can not be doped and there is a limit to improvement in cell characteristics such as battery capacity, rate characteristics, and life characteristics.
  • the doping element may be at least one or more selected from the group consisting of Al, Ti, Mn, Zr, Mg, Nb, Ca, F and Ni, and more preferably Al.
  • the doping element Al since the grain growth inhibiting effect is particularly large as compared with other doping elements (for example, Mg), the precursor which is a substituent is produced with a high content of doping as in the present invention, May be more preferable.
  • the precursor of the cathode active material doped with the doping element in the preparation of the precursor may have a certain concentration in the primary particle of the precursor.
  • the cathode active material precursor of the present invention comprises a precursor forming solution including a cobalt-containing starting material and a doping element source; And forming a precursor of Co 3 O 4 or CoOOH having an average particle diameter (D 50 ) of the primary particles of not less than 15 ⁇ m by containing at least 3,000 ppm of a doping element by coprecipitation reaction of the precursor forming solution do.
  • the doping element source is subjected to coprecipitation to perform precursor doping.
  • the doping element can be doped at a uniform concentration by doping the precursor by adding the doping element source together in the precursor coprecipitation step and the particle size of the doping precursor can be easily controlled by controlling the coprecipitation reaction time, But the precursor size can be easily increased.
  • the precursor preparation first provides a precursor forming solution comprising a cobalt-containing starting material and a doping element source.
  • the cobalt-containing starting material may be a sulfate, halide, acetate, sulfide, hydroxide, oxide, or oxyhydroxide containing cobalt, and is not particularly limited as long as it is soluble in water.
  • the cobalt-containing starting material is a Co (SO 4) 2 and 7H 2 O, CoCl 2, Co (OH) 2, Co (OCOCH 3) 2 and 4H 2 O or Co (NO 3) 2 and 6H 2 O, etc., and any one or a mixture of two or more of them may be used.
  • the doping element source may be a sulfate, nitrate, acetate, halide, hydroxide or oxyhydroxide containing a doping element, and any one or a mixture of two or more of them may be used.
  • the doping element may be at least one or more selected from the group consisting of Al, Ti, Mn, Zr, Mg, Nb, Ca, F and Ni, and more preferably Al as the doping element.
  • the precursor forming solution may be prepared by adding the cobalt-containing starting material and the doping element source to a solvent, specifically water or a mixture of water and an organic solvent (specifically, an alcohol or the like) which can be uniformly mixed with water, or A solution containing each of the cobalt-containing starting materials and a solution containing the doping element source may be prepared and then mixed and used.
  • a solvent specifically water or a mixture of water and an organic solvent (specifically, an alcohol or the like) which can be uniformly mixed with water, or
  • a solution containing each of the cobalt-containing starting materials and a solution containing the doping element source may be prepared and then mixed and used.
  • the precursor forming solution is coprecipitated to form a Co 3 O 4 or CoOOH precursor having an average particle size (D 50 ) of the primary particles of 3,000 ppm or more and a primary particle size of 15 ⁇ m or more.
  • the precursor solution was added to the reactor and form, doped with the co-precipitation reaction by adding a chelating agent and aqueous base element is doped more than 3,000ppm, 1 average particle diameter of primary particles (D 50) is less than 15 ⁇ m Co 3 O 4 Or a CoOOH precursor can be prepared.
  • the chelating agent examples include NH 4 OH, (NH 4 ) 2 SO 4 , NH 4 NO 3 , NH 4 Cl, CH 3 COONH 4 , and NH 4 CO 3 .
  • the above mixture may be used.
  • the chelating agent may be used in the form of an aqueous solution.
  • As the solvent water or a mixture of water and an organic solvent (specifically, alcohol or the like) that can be mixed with water and water may be used.
  • the basic compound may be a hydroxide of an alkali metal or an alkaline earth metal such as NaOH, KOH or Ca (OH) 2 , or a hydrate thereof, and either one of them or a mixture of two or more of them may be used.
  • the basic compound may also be used in the form of an aqueous solution.
  • As the solvent water or a mixture of water and an organic solvent (specifically, alcohol or the like) which can be uniformly mixed with water may be used. At this time, the concentration of the basic aqueous solution may be 2M to 10M.
  • the coprecipitation reaction for the production of the cathode active material precursor may be carried out at a pH of from 10 to 12. If the pH is out of the above range, there is a possibility that the size of the cathode active material precursor to be produced is changed or the particle cleavage is caused. More specifically, at a pH of 11 to a pH of 12. Such pH control can be controlled through the addition of a basic aqueous solution.
  • the coprecipitation reaction for the production of the cathode active material precursor may be performed in an inert atmosphere such as nitrogen at a temperature ranging from 30 ° C to 80 ° C.
  • a stirring process may be selectively performed, wherein the stirring speed may be from 100 rpm to 2000 rpm.
  • the Co 3 O 4 or CoOOH precursor of the primary particles in which the doping element is excessively doped is precipitated.
  • the content of the doping element doped in the precursor may be 3,000 ppm or more, more preferably 4,000 ppm or more.
  • the doping element can be doped with a high content.
  • the precursor thus prepared can be uniformly doped with the doping element without any concentration gradient from the center of the precursor particle of the cathode active material to the surface thereof.
  • the particle size of the doping precursor can be easily controlled by controlling the coprecipitation reaction time in the production of the precursor, the size of the precursor can easily be raised while doping with a high content.
  • the coprecipitation reaction time may be 10 to 40 hours, more preferably 10 to 30 hours.
  • the Co 3 O 4 or CoOOH precursor having an average particle size (D 50 ) of the primary particles of 15 ⁇ m or more can be formed by adjusting the coprecipitation time.
  • the precipitated Co 3 O 4 or CoOOH precursor may be selectively subjected to separation and drying processes according to a conventional method, and the drying process may be performed at 110 ° C. to 400 ° C. for 15 to 30 hours.
  • the present invention provides a cathode active material prepared using a precursor of an overdoped bulk as described above.
  • a cathode active material prepared using a precursor of an overdoped bulk as described above.
  • the cathode active material for secondary prevention of the present invention contains primary particles of lithium cobalt oxide, the primary particles contain 2,500 ppm or more of the doping element, the average particle diameter (D 50 ) of the primary particles is 15 mu m or more.
  • a precursor in the form of a secondary particle in which primary particles are aggregated is used, it is difficult to prepare a cathode active material having primary particles of 15 mu m or more due to the grain growth inhibition action of the high-dose doping element during the firing process.
  • the doping element Al since the particle growth inhibiting action is particularly large as compared with other doping elements (for example, Mg), the precursor which is a substituent is produced by doping with a high content as in the present invention, It may be more preferable to produce it.
  • the present invention is produced by using a precursor containing 3,000 ppm or more of the doping element and having an average particle diameter (D 50 ) of the primary particles of 15 ⁇ m or more as described above, the doping element is 2,500 ppm or more and an average particle diameter (D 50 ) of the primary particles of 15 ⁇ or more can be produced.
  • the cathode active material of the present invention is composed of primary particles of lithium cobalt oxide.
  • the average particle diameter (D 50 ) of the primary particles is 15 ⁇ m or more, and more preferably the average particle diameter (D 50 ) of the primary particles is 17 ⁇ m or more. It is possible to improve the battery capacity, energy density and lifetime characteristics by satisfying the average particle size (D 50 ) of the primary particles of the cathode active material of 15 ⁇ or more. In particular, when the average particle diameter (D 50 ) The capacity of the battery can be increased by significantly increasing the compression density of the anode by mixing the active material with the cathode active material of the small particle at a certain ratio.
  • the primary particles may contain a doping element in an amount of 2,500 ppm or more, more preferably 3,000 ppm or more in a doping element. Since the lithium source is further added in the production of the cathode active material, the content ratio (ppm) of the doping element of the cathode active material may be somewhat reduced compared with the content ratio (ppm) of the doping element contained in the cathode active material.
  • the primary particles of the cathode active material contain less than 2,500 ppm of the doping element, it is difficult to secure the structural stability of the lithium cobalt oxide cathode active material. In particular, the structural stability is lowered at a high voltage of 4.5 V or more, There is a problem that battery characteristics of the battery are deteriorated.
  • the doping element may be at least one or more selected from the group consisting of Al, Ti, Mn, Zr, Mg, Nb, Ca, F and Ni, and more preferably Al.
  • the doping element Al since the grain growth inhibiting effect is particularly large as compared with other doping elements (for example, Mg), the precursor which is a substituent is produced with a high content of doping as in the present invention, May be more preferable.
  • the doping element may have a constant concentration in the primary particles of the cathode active material particle.
  • the primary particles of the positive electrode active material may contain 50% or more of the entire content of the doping element in the central portion corresponding to 50% of the center of the radius of the particle from the center to the surface.
  • the lithium cobalt oxide may have a molar ratio (molar ratio of lithium / metal element (Co, M, etc.)) of metal elements (Co, M, etc.) other than lithium to lithium of 0.98 to 1.1.
  • the cathode active material according to an embodiment of the present invention may further include a surface layer on the particle surface of the lithium cobalt oxide and the surface layer may include Mg, Ti, Fe, Cu, Ca, Ba, Sn, Sb, At least one selected from the group consisting of Si, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Sc, Ce, Pr, Nd, Gd, Dy, Yb, Er, Co, One or more oxides.
  • the cathode active material of the present invention is obtained by mixing and firing a cathode active material precursor and a lithium source of the present invention to prepare a lithium cobalt-based compound having a doping element content of 2,500 ppm or more and having an average particle diameter (D 50 ) To form oxides.
  • the lithium source a lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide or oxyhydroxide may be used, and it is not particularly limited as long as it can be dissolved in water.
  • the lithium source material may be 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 Etc., and any one or a mixture of two or more of them may be used.
  • the amount of the lithium source to be used may be determined depending on the content of lithium (Li) and the metal element (Co, etc.) other than lithium in the finally produced lithium cobalt oxide. Specifically, the lithium cobalt- And the molar ratio of the metal element other than lithium (molar ratio of lithium / metal element) is from 0.98 to 1.1.
  • a sintering agent when the precursor and the lithium source are mixed, a sintering agent may be optionally added.
  • the sintering agent specifically includes a compound containing an ammonium ion such as NH 4 F, NH 4 NO 3 , or (NH 4 ) 2 SO 4 ; Metal oxides such as B 2 O 3 or Bi 2 O 3 ; Or metal halides such as NiCl 2 or CaCl 2, and any one or a mixture of two or more of them may be used.
  • the sintering may be used in an amount of 0.01 to 0.2 mol based on 1 mol of the precursor.
  • the effect of improving the sintering property of the cathode active material precursor may be insignificant. If the content of the sintering agent is excessively high, the excessive sintering agent may deteriorate the performance of the cathode active material And there is a possibility that the initial capacity of the battery is lowered during the charge / discharge process.
  • a moisture removing agent may be optionally added.
  • the moisture removing agent include citric acid, tartaric acid, glycolic acid, and maleic acid, and any one or a mixture of two or more thereof may be used.
  • the moisture scavenger may be used in an amount of 0.01 to 0.2 mol based on 1 mol of the precursor.
  • the firing may be performed at 900 ° C to 1,100 ° C, and more preferably 1,000 to 1,050 ° C. If the calcination temperature is less than 900 ° C., there is a fear that the discharge capacity per unit weight, the cycle characteristics, and the operating voltage may decrease due to the residual unreacted raw material. If the calcination temperature is more than 1,100 ° C., There is a fear of lowering the discharge capacity per unit time, lowering the cycle characteristics, and lowering the operating voltage.
  • the calcination may be performed in an oxidizing atmosphere such as air or oxygen or a reducing atmosphere containing nitrogen or hydrogen for 5 to 30 hours.
  • a surface layer containing an inorganic oxide may be further formed on the surface of the lithium co-based oxide thus produced.
  • the surface layer may include at least one of Mg, Ti, Fe, Cu, Ca, Ba, Sn, Sb, Na, Z, Si, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, And at least one kind of oxide selected from the group consisting of Gd, Dy, Yb, Er, Co, Al, Ga and B is mixed with the coating material containing the element forming the surface layer, Can be formed.
  • the cathode active material of lithium cobalt oxide prepared as described above over-doped the doping element to solve the grain growth inhibition problem caused by the doping element while having the structural stability under high voltage, so that the average particle diameter (D 50 ) of the primary particles was 15 ⁇ Or more. Therefore, the cathode active material can be used for a high-voltage secondary battery of 4.5V or higher, and can realize a high capacity and significantly improve lifetime characteristics.
  • a positive electrode and a lithium secondary battery for a lithium secondary battery including the positive electrode active material.
  • the positive electrode includes a positive electrode collector and a positive electrode active material layer formed on the positive electrode collector and including the positive electrode active material.
  • the cathode current collector is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and for example, a metal such as stainless steel, aluminum, nickel, titanium, sintered carbon, , Nickel, titanium, silver, or the like may be used.
  • the cathode current collector may have a thickness of 3 to 500 ⁇ , and fine unevenness may be formed on the surface of the cathode current collector to increase the adhesive force of the cathode active material.
  • it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.
  • the cathode active material layer may include a conductive material and a binder together with the cathode active material described above.
  • the conductive material is used for imparting conductivity to the electrode.
  • the conductive material can be used without particular limitation as long as it has electron conductivity without causing chemical change. Specific examples thereof 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 powder or metal fibers such as copper, nickel, aluminum and silver; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; And polyphenylene derivatives. These may be used alone or in admixture of two or more.
  • the conductive material may be typically contained in an amount of 1 to 30% by weight based on the total weight of the cathode active material layer.
  • the binder serves to improve adhesion between the positive electrode active material particles and adhesion between the positive electrode active material and the positive electrode collector.
  • specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose ), Starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, and various copolymers thereof.
  • the binder may be included in an amount of 1 to 30% by weight based on the total weight of the cathode active material layer.
  • the positive electrode may be manufactured according to a conventional positive electrode manufacturing method, except that the positive electrode active material described above is used. Specifically, the composition for forming a cathode active material layer containing the above-mentioned cathode active material and optionally a binder and a conductive material may be coated on the cathode current collector, followed by drying and rolling. At this time, the types and contents of the cathode active material, the binder, and the conductive material are as described above.
  • the solvent examples include dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, and the like. Water and the like, and one kind or a mixture of two or more kinds can be used.
  • the amount of the solvent to be used is sufficient to dissolve or disperse the cathode active material, the conductive material and the binder in consideration of the coating thickness of the slurry and the yield of the slurry, and then to have a viscosity capable of exhibiting excellent thickness uniformity Do.
  • the positive electrode may be produced by casting the composition for forming the positive electrode active material layer on a separate support, then peeling off the support from the support, and laminating the obtained film on the positive electrode current collector.
  • an electrochemical device including the anode.
  • the electrochemical device may be specifically a battery or a capacitor, and more specifically, may be a lithium secondary battery.
  • the lithium secondary battery includes a positive electrode, a negative electrode disposed opposite to the positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, as described above.
  • the lithium secondary battery may further include a battery container for storing the positive electrode, the negative electrode and the electrode assembly of 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 disposed 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 changes in the battery.
  • the negative electrode current collector may be formed on the surface of copper, stainless steel, aluminum, nickel, titanium, sintered carbon, Carbon, nickel, titanium, silver or the like, aluminum-cadmium alloy, or the like may be used.
  • the negative electrode collector may have a thickness of 3 to 500 ⁇ , and similarly to the positive electrode collector, fine unevenness may be formed on the surface of the collector to enhance the binding force of the negative electrode active material.
  • it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.
  • the anode active material layer optionally includes a binder and a conductive material together with the anode active material.
  • the negative electrode active material layer may be formed by applying and drying a composition for forming a negative electrode including a negative electrode active material on the negative electrode collector and, optionally, a binder and a conductive material, or by casting the composition for forming a negative electrode on a separate support , And a film obtained by peeling from the support may be laminated on the negative electrode collector.
  • a compound capable of reversible intercalation and deintercalation of lithium may be used.
  • Specific examples thereof 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 alloys, Sn alloys or Al alloys;
  • Metal oxides capable of doping and dedoping lithium such as SiO x (0 ⁇ x ⁇ 2), SnO 2 , vanadium oxide, and lithium vanadium oxide;
  • a composite containing the metallic compound and the carbonaceous material such as Si-C composite or Sn-C composite, 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.
  • the carbon material may be both low-crystalline carbon and high-crystallinity carbon.
  • Examples of the low-crystalline carbon include soft carbon and hard carbon.
  • Examples of the highly crystalline carbon include natural graphite, artificial graphite, artificial graphite or artificial graphite, Kish graphite graphite, pyrolytic carbon, mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches and petroleum or coal tar coke derived cokes).
  • binder and the conductive material may be the same as those described above for the anode.
  • the separator separates the negative electrode and the positive electrode and provides a moving path of lithium ions.
  • the separator can be used without any particular limitation as long as it is used as a separator in a lithium secondary battery. Particularly, It is preferable to have a low resistance and an excellent ability to impregnate the electrolyte.
  • porous polymer films such as porous polymer films made of polyolefin-based polymers such as ethylene homopolymers, propylene homopolymers, ethylene / butene copolymers, ethylene / hexene copolymers and ethylene / methacrylate copolymers, May be used.
  • a nonwoven fabric made of a conventional porous nonwoven fabric for example, glass fiber of high melting point, polyethylene terephthalate fiber, or the like may be used.
  • a coated separator containing a ceramic component or a polymer material may be used, and may be optionally used as a single layer or a multilayer structure.
  • Examples of the electrolyte used in the present invention include an organic-based liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, and a molten inorganic electrolyte that can be used in the production of a lithium secondary battery. It is not.
  • the electrolyte may include an organic solvent and a lithium salt.
  • the organic solvent may be used without limitation as long as it can act as a medium through which ions involved in the electrochemical reaction of the battery can move.
  • examples of the organic solvent include ester solvents such as methyl acetate, ethyl acetate,? -Butyrolactone and?
  • Ether solvents such as dibutyl ether or tetrahydrofuran; Ketone solvents such as cyclohexanone; Aromatic hydrocarbon solvents such as benzene and fluorobenzene; Dimethyl carbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), propylene carbonate PC) and the like; Alcohol solvents such as ethyl alcohol and isopropyl alcohol; R-CN (R is a straight, branched or cyclic hydrocarbon group of C2 to C20, which may contain a double bond aromatic ring or an ether bond); Amides such as dimethylformamide; Dioxolanes such as 1,3-dioxolane; Or sulfolane may be used.
  • Ether solvents such as dibutyl ether or tetrahydrofuran
  • Ketone solvents such as cyclohexanone
  • a carbonate-based solvent is preferable, and a cyclic carbonate (for example, ethylene carbonate or propylene carbonate) having a high ionic conductivity and a high dielectric constant, for example, such as ethylene carbonate or propylene carbonate, For example, ethyl methyl carbonate, dimethyl carbonate or diethyl carbonate) is more preferable.
  • a cyclic carbonate for example, ethylene carbonate or propylene carbonate
  • ethylene carbonate or propylene carbonate for example, ethylene carbonate or propylene carbonate
  • ethyl methyl carbonate, dimethyl carbonate or diethyl carbonate ethyl methyl carbonate, dimethyl carbonate or diethyl carbonate
  • the lithium salt can 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 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 may be used.
  • the concentration of the lithium salt is preferably in the range of 0.1 to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte has an appropriate conductivity and viscosity, so that it can exhibit excellent electrolyte performance and the lithium ion can effectively move.
  • the electrolyte may contain, for example, a haloalkylene carbonate-based compound such as difluoroethylene carbonate or the like, pyridine, triethanolamine, or the like for the purpose of improving lifetime characteristics of the battery, Ethyl phosphite, triethanol amine, cyclic ether, ethylenediamine, glyme, hexametriamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, At least one additive such as benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, 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 cathode active material according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, it can be used in portable devices such as mobile phones, notebook computers, digital cameras, and hybrid electric vehicles hybrid electric vehicle (HEV)).
  • portable devices such as mobile phones, notebook computers, digital cameras, and hybrid electric vehicles hybrid electric vehicle (HEV)).
  • HEV hybrid electric vehicles hybrid electric vehicle
  • a battery module including the lithium secondary battery as a unit cell and a battery pack including the same.
  • the battery module or the battery pack may include a power tool; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); Or a power storage system, as shown in FIG.
  • a power tool including an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); Or a power storage system, as shown in FIG.
  • EV electric vehicle
  • PHEV plug-in hybrid electric vehicle
  • the cathode active material precursor (5,000 ppm Al-doped Co 3 O 4 ) prepared as in Example 1 and Li 2 CO 3 as a lithium source were mixed at a molar ratio of Li / Co of 1.035 and calcined at 1,000 ° C. for 17 hours to obtain 4,500 ppm Al-doped lithium cobalt oxide was prepared.
  • the cathode active material precursor (3,000 ppm Al-doped Co 3 O 4 ) prepared as in Example 2 and Li 2 CO 3 as a lithium source were mixed at a molar ratio of Li / Co of 1.035 and calcined at 1,000 ° C. for 17 hours to give 2,500 ppm Al-doped lithium cobalt oxide was prepared.
  • the cathode active material precursor (3,000 ppm Al-doped Co 3 O 4 ) prepared as in Comparative Example 1 and Li 2 CO 3 as a lithium source were mixed at a Li / Co 1.045 molar ratio and calcined at 1,020 ° C. for 20 hours to obtain 2,500 ppm Al-doped lithium cobalt oxide was prepared.
  • the thus prepared cathode active material was doped with a concentration gradient gradually decreasing from the surface to the inside of Al.
  • the thus prepared cathode active material was grown up to 12 ⁇ in primary particle size, but no abnormal growth was caused due to interference of grain growth of Al.
  • FIG. 1 (Example 1) and FIG. 2 (Comparative Example 1) show photographs of the cathode active material precursor powder prepared in Example 1 and Comparative Example 1 magnified with a scanning electron microscope (SEM).
  • SEM scanning electron microscope
  • the cathode active material precursor of Co 3 O 4 prepared in Example 1 and Comparative Example 1 is composed of primary particles, and Example 1 (FIG. 1) , And Comparative Example 1 (Fig. 2) formed small particles with a primary particle size of about 7 mu m.
  • the average particle diameters of the primary particles of the cathode active material precursor and the cathode active material prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were measured by Particle Size Distribution (PSD), and the results are shown in Table 1 below .
  • Example 1 Example 2 Example 3
  • Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 4
  • the average particle diameter (D 50 ) of the primary particles of the precursor was 15 ⁇ m or more in Example 1 and Example 2, and the precursors of Example 1 and Example 2 were used,
  • Al was doped with a high content of not less than 2,500 ppm without increasing the firing temperature and the amount of lithium input, and the cathode active material having a primary particle average particle diameter (D 50 ) .
  • Comparative Example 1 it was confirmed that the average particle diameter (D 50 ) of the primary particles of the precursor was 7 ⁇ m, and in Comparative Example 2 in which the cathode active material was prepared using the precursor of Comparative Example 1, The average particle diameter (D 50 ) of the primary particles was only 12 ⁇ , and the cathode active material could not be prepared.
  • Comparative Example 4 produced using the secondary particle type precursor in which the primary particles aggregated, the primary particles were grown up to 12 ⁇ , but no abnormal growth was caused due to the grain growth inhibiting action of Al .
  • lithium metal was used for the cathode.
  • a lithium secondary battery was prepared by preparing an electrode assembly between a positive electrode and a negative electrode manufactured as described above through a separator of porous polyethylene, positioning the electrode assembly inside a case, and then injecting an electrolyte into the case.
  • Each lithium secondary battery cell thus prepared was charged at 0.5 C and 4.55 V in a CCCV mode at 25 ⁇ and 45 ⁇ , cut off at a temperature of 0.05 C, (Capacity Retention [%]) was measured while discharging at a constant current of 3.0 V and performing charge / discharge 50 times. The results are shown in Table 2.
  • Example 3 Example 4 Comparative Example 2 Comparative Example 3 Comparative Example 4 Capacity (mAh / g) 207 209 209 209 208 Rate characteristic (%) 92.8 92.5 91.7 91.8 91.5 25 C 50 Cycle Capacity Retention (%) 96 95 92 93 92 45 C 50 Cycle Capacity Retention (%) 95 95 91 91 90

Abstract

The present invention provides: a cathode active material precursor for a secondary battery, comprising a primary particle of Co3O4 or CoOOH, wherein the primary particle contains 3,000 ppm or more of a doping element, and the average particle diameter (D50) of the primary particle is 15 ㎛ or more; and a cathode active material for a secondary battery, comprising a primary particle of a lithium cobalt-based oxide, wherein the primary particle contains 2,500 ppm or more of a doping element, and the average particle diameter (D50) of the primary particle is 15 ㎛ or more.

Description

이차전지용 양극 활물질 전구체, 양극 활물질 및 이를 포함하는 리튬 이차전지A cathode active material precursor for a secondary battery, a cathode active material, and a lithium secondary battery comprising the same
관련출원과의 상호인용Mutual citation with related application
본 출원은 2017년 9월 19일자 한국 특허 출원 제10-2017-0120645호 및 2018년 9월 18일자 한국 특허 출원 제10-2018-0111642호에 기초한 우선권의 이익을 주장하며, 해당 한국 특허 출원의 문헌에 개시된 모든 내용은 본 명세서의 일부로서 포함된다.This application claims the benefit of priority based on Korean Patent Application No. 10-2017-0120645 filed on September 19, 2017, and Korean Patent Application No. 10-2018-0111642 filed on September 18, 2018, The entire contents of which are incorporated herein by reference.
기술분야Technical field
본 발명은 이차전지용 양극 활물질 전구체, 양극 활물질 및 이를 포함하는 리튬 이차전지에 관한 것이다.The present invention relates to a cathode active material precursor for a secondary battery, a cathode active material, and a lithium secondary battery comprising the same.
최근 휴대전화, 노트북 컴퓨터, 전기 자동차 등 전지를 사용하는 전자기구의 급속한 보급에 수반하여 소형 경량이면서도 상대적으로 고용량인 이차전지의 수요가 급속히 증대되고 있다. 특히, 리튬 이차전지는 경량이고 고에너지 밀도를 가지고 있어 휴대 기기의 구동 전원으로서 각광을 받고 있다. 이에 따라, 리튬 이차전지의 성능향상을 위한 연구개발 노력이 활발하게 진행되고 있다. 2. Description of the Related Art In recent years, with the rapid spread of electronic devices using batteries such as mobile phones, notebook computers, electric vehicles, and the like, the demand for secondary batteries of small size and light weight and relatively high capacity has been rapidly increasing. Particularly, the lithium secondary battery is light in weight and has a high energy density, and is attracting attention as a driving power source for portable devices. Accordingly, research and development efforts for improving the performance of the lithium secondary battery have been actively conducted.
리튬 이차전지는 리튬 이온의 삽입/탈리가 가능한 양극 활물질을 포함하고 있는 양극과, 리튬 이온의 삽입/탈리가 가능한 음극 활물질을 포함하고 있는 음극, 상기 양극과 음극 사이에 미세 다공성 분리막이 개재된 전극 조립체에 리튬 이온을 함유한 전해질이 포함되어 있는 전지를 의미한다. The lithium secondary battery includes a cathode including a cathode active material capable of intercalating / deintercalating lithium ions, a cathode including a cathode active material capable of intercalating / deintercalating lithium ions, an electrode including a microporous separator interposed between the cathode and the anode, Means a battery in which an electrolyte containing lithium ions is contained in an assembly.
리튬 이차전지의 양극 활물질로는 리튬 전이금속 산화물이 사용되고, 음극 활물질로는 리튬 금속, 리튬 합금, 결정질 또는 비정질 탄소 또는 탄소 복합체 등이 사용되고 있다. 상기 활물질을 적당한 두께와 길이로 전극 집전체에 도포하거나 또는 활물질 자체를 필름 형상으로 도포하여 절연체인 분리막과 함께 감거나 적층하여 전극군을 만든 다음, 캔 또는 이와 유사한 용기에 넣은 후, 전해액을 주입하여 이차전지를 제조한다.A lithium transition metal oxide is used as the positive electrode active material of the lithium secondary battery, and lithium metal, lithium alloy, crystalline or amorphous carbon or carbon composite is used as the negative electrode active material. The active material is coated on the electrode current collector with an appropriate thickness and length, or the active material itself is coated in a film form and wrapped or laminated with a separator as an insulator to form an electrode group. The electrode group is then placed in a can or similar container, Thereby manufacturing a secondary battery.
현재 활발하게 연구 개발되어 사용되고 있는 리튬 이차전지의 양극 활물질로는 층상구조의 리튬 코발트 산화물(LiCoO2)이 있다. 리튬 코발트 산화물(LiCoO2)은 작동 전압이 높고 용량 특성이 우수한 장점이 있으나, 탈 리튬에 따른 결정 구조의 불안정화로 열적 특성이 열악하고, 고전압 하에서 구조가 불안정해지는 문제가 있다. Lithium cobalt oxide (LiCoO 2 ) has a layered structure as a cathode active material of a lithium secondary battery that has been actively researched and used at present. Lithium cobalt oxide (LiCoO 2 ) has an advantage of high operating voltage and excellent capacity characteristics, but its thermal characteristics are poor due to the destabilization of the crystal structure due to lithium remnants and the structure becomes unstable under high voltage.
최근 고용량 리튬 이차전지에 대한 요구가 점차 커지고 있는 상황인데, 리튬 코발트 산화물(LiCoO2)의 경우 삼성분계 양극 활물질과 달리 전압을 올림으로써만 용량 증가가 가능하기 때문에, 기존의 4.45V 이하보다 더욱 고전압인 4.5V 이상에서도 구조 안정성을 확보할 수 있는 리튬 코발트 산화물(LiCoO2)의 개발이 필요한 실정이다.In recent years, lithium cobalt oxide (LiCoO 2 ) has been increasingly required for a high capacity lithium secondary battery. Unlike a tin oxide cathode active material, the capacity can be increased only by raising the voltage. Therefore, It is necessary to develop lithium cobalt oxide (LiCoO 2 ) capable of securing the structural stability even at 4.5 V or more.
4.5V 이상의 고전압 하에서 안정적으로 구동하는 리튬 코발트 산화물(LiCoO2)를 제조하기 위해, 도핑 원소를 과량으로 도핑하는 기술이 시도되고 있으나, 이때, 과량 도핑된 도핑 원소가 양극 활물질의 성장을 방해하여 대입자의 양극 활물질을 제조하기 어려운 문제가 있었다.In order to produce lithium cobalt oxide (LiCoO 2 ) which is stably driven at a high voltage of 4.5V or more, a technique of doping an excessive amount of a doping element has been attempted. However, excessive doping of the doping element prevents the growth of the cathode active material There is a problem that it is difficult to produce a cathode active material of the present invention.
본 발명은 도핑 원소를 과량 도핑하여 고전압 하에서도 구조 안정성을 가지면서도, 도핑 원소에 의한 입자 성장 방해 문제를 해결하여 평균 입경(D50) 15㎛ 이상의 대입자인 리튬 코발트 산화물의 양극 활물질을 제공하고자 하는 것이다.An object of the present invention is to provide a cathode active material of lithium cobalt oxide which is an acceptor having an average particle diameter (D 50 ) of 15 μm or more by solving the problem of obstructing grain growth by a doping element while having structural stability under high voltage by excessively doping a doping element will be.
본 발명은 Co3O4 또는 CoOOH의 1차 입자를 포함하며, 상기 1차 입자는 도핑 원소를 3,000ppm 이상 함유하고, 상기 1차 입자의 평균 입경(D50)이 15㎛ 이상인 이차전지용 양극 활물질 전구체를 제공한다.The present invention relates to a secondary battery comprising a primary particle of Co 3 O 4 or CoOOH, wherein the primary particle contains 3,000 ppm or more of a doping element and the average particle diameter (D 50 ) of the primary particle is 15 μm or more Precursor.
또한, 본 발명은 리튬 코발트계 산화물의 1차 입자를 포함하며, 상기 1차 입자는 도핑 원소를 2,500ppm 이상 함유하고, 상기 1차 입자의 평균 입경(D50)이 15㎛ 이상인 이차전지용 양극 활물질을 제공한다.The present invention also provides a lithium secondary battery comprising a primary particle of a lithium cobalt oxide, wherein the primary particle contains a doping element in an amount of 2,500 ppm or more, and the primary particle has an average particle diameter (D 50 ) .
또한, 본 발명은 코발트 함유 출발물질 및 도핑 원소 소스를 포함하는 전구체 형성 용액을 마련하는 단계; 및 상기 전구체 형성 용액을 공침 반응시켜, 도핑 원소가 3,000ppm 이상 함유되고, 1차 입자의 평균 입경(D50)이 15㎛ 이상인 Co3O4 또는 CoOOH의 전구체를 형성하는 단계;를 포함하는 이차전지용 양극 활물질 전구체의 제조방법을 제공한다.The present invention also provides a method of forming a precursor, comprising: providing a precursor forming solution comprising a cobalt-containing starting material and a doping element source; And forming a precursor of Co 3 O 4 or CoOOH having an average particle diameter (D 50 ) of the primary particles of not less than 15 μm and containing the doping element in an amount of 3,000 ppm or more by coprecipitation reaction with the precursor forming solution, A method for manufacturing a positive electrode active material precursor for a battery is provided.
또한, 본 발명은 제1항에 따른 양극 활물질 전구체 분말 및 리튬 소스를 혼합하고 소성하여, 도핑 원소가 2,500ppm 이상 함유되고, 1차 입자의 평균 입경(D50)이 15㎛ 이상인 리튬 코발트계 산화물을 형성하는 이차전지용 양극 활물질의 제조방법을 제공한다.The cathode active material precursor powder and the lithium source according to the present invention are mixed and sintered to prepare a lithium cobalt oxide having an average particle size (D 50 ) of the primary particles of not less than 2,500 ppm and having a primary particle size of not less than 15 μm The present invention also provides a method for producing a cathode active material for a secondary battery.
또한, 본 발명은 상기 양극 활물질을 포함하는 양극 및 리튬 이차전지를 제공한다.The present invention also provides a positive electrode and a lithium secondary battery including the positive electrode active material.
본 발명에 따르면, 도핑 원소를 과량 도핑하여 고전압 하에서도 구조 안정성을 가지면서도, 도핑 원소에 의한 입자 성장 방해 문제를 해결하여 평균 입경(D50) 15㎛ 이상의 대입자인 리튬 코발트 산화물의 양극 활물질을 제공할 수 있다.According to the present invention, there is provided a cathode active material of lithium cobalt oxide, which is an acceptor having an average particle diameter (D 50 ) of 15 μm or more, by solving the problem of obstructing grain growth by a doping element while having structural stability under high voltage by excessively doping the doping element can do.
도 1은 본 발명의 실시예 1에 따라 제조된 양극 활물질의 전구체를 확대 관찰한 주사전자현미경(SEM, Scanning Electron Microscope)사진이다.1 is a scanning electron microscope (SEM) photograph of a precursor of a cathode active material prepared according to Example 1 of the present invention.
도 2는 본 발명의 비교예 1에 따라 제조된 양극 활물질의 전구체를 확대 관찰한 주사전자현미경(SEM, Scanning Electron Microscope)사진이다.2 is a scanning electron microscope (SEM) photograph of a precursor of a cathode active material prepared according to Comparative Example 1 of the present invention.
이하, 본 발명에 대한 이해를 돕기 위해 본 발명을 더욱 상세하게 설명한다. 이때, 본 명세서 및 청구범위에 사용된 용어나 단어는 통상적이거나 사전적인 의미로 한정해서 해석되어서는 아니 되며, 발명자는 그 자신의 발명을 가장 최선의 방법으로 설명하기 위해 용어의 개념을 적절하게 정의할 수 있다는 원칙에 입각하여본 발명의 기술적 사상에 부합하는 의미와 개념으로 해석되어야만 한다.Hereinafter, the present invention will be described in detail in order to facilitate understanding of the present invention. Herein, terms and words used in the present specification and claims should not be construed to be limited to ordinary or dictionary meanings, and the inventor may appropriately define the concept of the term to describe its own invention in the best way. It should be construed as meaning and concept consistent with the technical idea of the present invention.
본 발명은 양극 활물질 전구체 제조시, 전구체에 과량의 도핑 원소를 도핑하고, 전구체 입자 사이즈를 평균 입경(D50) 15㎛ 이상까지 키워 대입자의 전구체를 제조한다. 이와 같이 과량 도핑된 대입자의 전구체를 사용하여 양극 활물질을 제조하면, 소성 온도 증가 및 리튬 투입량 증가 없이도 대입자의 양극 활물질을 제조할 수 있다.In preparing a precursor of a cathode active material, a precursor is doped with an excessive amount of a doping element, and a precursor particle size is increased up to an average particle diameter (D 50 ) of 15 μm or more to prepare a precursor of an acceptor. When the cathode active material is prepared by using the precursor of the overdoped large electrode, the cathode active material of the recipient can be produced without increasing the firing temperature and increasing the amount of lithium input.
구체적으로, 본 발명의 이차전지용 양극 활물질 전구체는 Co3O4 또는 CoOOH의 1차 입자를 포함하며, 상기 1차 입자는 도핑 원소를 3,000ppm 이상 함유하고, 상기 1차 입자의 평균 입경(D50)이 15㎛ 이상이다.Specifically, the cathode active material precursor for a secondary battery according to the present invention comprises primary particles of Co 3 O 4 or CoOOH, wherein the primary particles contain 3,000 ppm or more of a doping element, and the average particle diameter of the primary particles (D 50 ) Is not smaller than 15 mu m.
본 발명의 양극 활물질 전구체는 Co3O4 또는 CoOOH의 1차 입자로 구성된다. 본 발명의 양극 활물질 전구체는 1차 입자가 집합하여 형성되는 2차 입자가 아니며, 물리적으로 분별되지 않는 1차 입자인 것이 바람직하다. The cathode active material precursor of the present invention is composed of primary particles of Co 3 O 4 or CoOOH. The positive electrode active material precursor of the present invention is preferably a primary particle that is not a secondary particle formed by aggregation of primary particles but is not physically separated.
본 발명의 양극 활물질 전구체는 상기 1차 입자의 평균 입경(D50)이 15㎛ 이상이 되도록 하며, 보다 바람직하게는 상기 1차 입자의 평균 입경(D50)이 17㎛ 이상일 수 있다. 상기 양극 활물질 전구체의 1차 입자의 평균 입경(D50)이 15㎛ 미만일 경우, 15㎛ 미만의 전구체를 사용하여 소성 공정을 거쳐 양극 활물질을 제조할 때, 도핑 원소가 입자 성장을 방해하여 평균 입경(D50)이 15㎛ 이상인 양극 활물질을 제조하기 어려운 문제가 발생한다. 양극 활물질을 평균 입경(D50) 15㎛ 이상의 대입자로 제조하지 못하게 되면, 양극의 압축 밀도를 증가시키는데 한계가 있으며, 전지 용량 증가에 어려움이 있다.In the cathode active material precursor of the present invention, the average particle diameter (D 50 ) of the primary particles is 15 μm or more, and more preferably the average particle diameter (D 50 ) of the primary particles is 17 μm or more. When the average particle diameter (D 50 ) of the primary particles of the cathode active material precursor is less than 15 탆, when the cathode active material is produced through a firing process using a precursor of less than 15 탆, the doping element interferes with the particle growth, There arises a problem that it is difficult to produce a cathode active material having a thickness (D 50 ) of 15 μm or more. If the positive electrode active material can not be made into an average particle diameter (D 50 ) of 15 μm or more, there is a limit to increase the compression density of the positive electrode and it is difficult to increase the battery capacity.
또한, 본 발명의 양극 활물질 전구체는 상기 1차 입자가 도핑 원소를 3,000ppm 이상 함유하며, 보다 바람직하게는 도핑 원소를 4,000ppm 이상 함유할 수 있다. 상기 양극 활물질 전구체의 1차 입자가 도핑 원소를 3,000ppm 미만으로 함유할 경우, 리튬 코발트계 산화물 양극 활물질의 구조 안정성을 확보하기 어려우며, 특히, 4.5V 이상의 고전압 하에서 구조 안정성이 낮아져 상온 및 고온 수명 특성이 저하되는 등 전지 특성 저하의 문제가 있을 수 있다.In addition, the cathode active material precursor of the present invention may contain not less than 3,000 ppm of the doping element and more preferably not less than 4,000 ppm of the doping element. When the primary particles of the cathode active material precursor contain less than 3,000 ppm of the doping element, it is difficult to secure the structural stability of the lithium cobalt oxide cathode active material. In particular, when the primary particles of the cathode active material precursor have low structural stability at a high voltage of 4.5 V or higher, There may be a problem of deterioration of battery characteristics.
한편, 본 발명과 같이 고함량 도핑된 전구체를 형성하는 것이 아니라, 도핑되지 않은 전구체를 대입자로 형성하고, 리튬 소스와 함께 소성할 때 도핑 원소를 추가로 투입하여 고함량의 도핑을 할 경우, 고함량의 도핑 원소가 균일한 농도를 갖고 도핑되지 못하고, 전지 용량, 율 특성 및 수명 특성 등의 전지 특성 개선에 한계가 있을 수 있다. On the other hand, in the case where a high-dose doped precursor is formed instead of forming a high-doped precursor as in the present invention, and a doping element is further added to the precursor when the undoped precursor is formed as a substituent, Doping element having a uniform concentration can not be doped and there is a limit to improvement in cell characteristics such as battery capacity, rate characteristics, and life characteristics.
상기 도핑 원소는 Al, Ti, Mn, Zr, Mg, Nb, Ca, F 및 Ni로 이루어진 군에서 선택된 적어도 1종 이상일 수 있으며, 보다 바람직하게는 Al일 수 있다. 도핑 원소 Al의 경우, 다른 도핑 원소(예를 들면, Mg)에 비하여 특히 입자 성장 방해 작용이 크기 때문에, 본 발명과 같이 고함량 도핑되면서 대입자인 전구체를 제조한 후 이를 사용하여 양극 활물질을 제조하는 것이 보다 바람직할 수 있다. The doping element may be at least one or more selected from the group consisting of Al, Ti, Mn, Zr, Mg, Nb, Ca, F and Ni, and more preferably Al. In the case of the doping element Al, since the grain growth inhibiting effect is particularly large as compared with other doping elements (for example, Mg), the precursor which is a substituent is produced with a high content of doping as in the present invention, May be more preferable.
상기와 같이 전구체 제조시 도핑 원소를 도핑한 양극 활물질 전구체는 상기 도핑 원소가 전구체의 1차 입자 내에서 일정한 농도를 가질 수 있다.As described above, the precursor of the cathode active material doped with the doping element in the preparation of the precursor may have a certain concentration in the primary particle of the precursor.
다음으로, 본 발명의 양극 활물질 전구체의 제조방법을 설명한다.Next, a method for producing the positive electrode active material precursor of the present invention will be described.
본 발명의 상기 양극 활물질 전구체는 코발트 함유 출발물질 및 도핑 원소 소스를 포함하는 전구체 형성 용액을 마련하는 단계; 및 상기 전구체 형성 용액을 공침 반응시켜, 도핑 원소가 3,000ppm 이상 함유되고, 1차 입자의 평균 입경(D50)이 15㎛ 이상인 Co3O4 또는 CoOOH의 전구체를 형성하는 단계;를 포함하여 제조한다.The cathode active material precursor of the present invention comprises a precursor forming solution including a cobalt-containing starting material and a doping element source; And forming a precursor of Co 3 O 4 or CoOOH having an average particle diameter (D 50 ) of the primary particles of not less than 15 μm by containing at least 3,000 ppm of a doping element by coprecipitation reaction of the precursor forming solution do.
본 발명은 양극 활물질 전구체 제조시, 도핑 원소 소스를 함께 공침 반응시켜 전구체 도핑을 한다. 전구체 공침 단계에서 도핑 원소 소스를 함께 첨가하여 전구체 도핑함으로써, 균일한 농도로 도핑 원소를 도핑할 수 있으며, 공침 반응 시간을 조절하여 도핑 전구체의 입자 사이즈를 용이하게 조절할 수 있기 때문에 고함량의 도핑을 하면서도 전구체 사이즈를 용이하게 키울 수 있다.In preparing a cathode active material precursor, the doping element source is subjected to coprecipitation to perform precursor doping. The doping element can be doped at a uniform concentration by doping the precursor by adding the doping element source together in the precursor coprecipitation step and the particle size of the doping precursor can be easily controlled by controlling the coprecipitation reaction time, But the precursor size can be easily increased.
상기 전구체 제조는 먼저, 코발트 함유 출발물질 및 도핑 원소 소스를 포함하는 전구체 형성 용액을 마련한다.The precursor preparation first provides a precursor forming solution comprising a cobalt-containing starting material and a doping element source.
상기 코발트 함유 출발물질은 코발트는 함유하는 황산염, 할라이드, 아세트산염, 황화물, 수산화물, 산화물 또는 옥시수산화물 등이 사용될 수 있으며, 물에 용해될 수 있는 것이라면 특별히 한정되지 않는다. 예를 들어, 상기 코발트 함유 출발물질은 Co(SO4)2ㆍ7H2O, CoCl2, Co(OH)2, Co(OCOCH3)2ㆍ4H2O 또는 Co(NO3)2ㆍ6H2O 등을 들 수 있으며, 이들 중 어느 하나 또는 둘 이상의 혼합물이 사용될 수 있다.The cobalt-containing starting material may be a sulfate, halide, acetate, sulfide, hydroxide, oxide, or oxyhydroxide containing cobalt, and is not particularly limited as long as it is soluble in water. For example, the cobalt-containing starting material is a Co (SO 4) 2 and 7H 2 O, CoCl 2, Co (OH) 2, Co (OCOCH 3) 2 and 4H 2 O or Co (NO 3) 2 and 6H 2 O, etc., and any one or a mixture of two or more of them may be used.
상기 도핑 원소 소스는 도핑 원소를 함유하는 황산염, 질산염, 아세트산염, 할라이드, 수산화물 또는 옥시수산화물 등을 들 수 있으며, 이들 중 어느 하나 또는 둘 이상의 혼합물이 사용될 수 있다. 상기 도핑 원소는 Al, Ti, Mn, Zr, Mg, Nb, Ca, F 및 Ni로 이루어진 군에서 선택된 적어도 1종 이상일 수 있으며, 보다 바람직하게는 도핑 원소로서 Al를 포함할 수 있다. The doping element source may be a sulfate, nitrate, acetate, halide, hydroxide or oxyhydroxide containing a doping element, and any one or a mixture of two or more of them may be used. The doping element may be at least one or more selected from the group consisting of Al, Ti, Mn, Zr, Mg, Nb, Ca, F and Ni, and more preferably Al as the doping element.
상기 전구체 형성 용액은 상기 코발트 함유 출발물질 및 도핑 원소 소스를 용매, 구체적으로는 물, 또는 물과 균일하게 혼합 가능한 유기 용매(구체적으로, 알코올 등)와 물의 혼합물에 첨가하여 제조할 수도 있고, 또는 각각의 코발트 함유 출발물질을 포함하는 용액 및 도핑 원소 소스를 포함하는 용액을 제조한 후 이를 혼합하여 사용할 수도 있다.The precursor forming solution may be prepared by adding the cobalt-containing starting material and the doping element source to a solvent, specifically water or a mixture of water and an organic solvent (specifically, an alcohol or the like) which can be uniformly mixed with water, or A solution containing each of the cobalt-containing starting materials and a solution containing the doping element source may be prepared and then mixed and used.
다음으로, 상기 전구체 형성 용액을 공침 반응시켜, 도핑 원소가 3,000ppm 이상 함유되고, 1차 입자의 평균 입경(D50)이 15㎛ 이상인 Co3O4 또는 CoOOH 전구체를 형성한다.Next, the precursor forming solution is coprecipitated to form a Co 3 O 4 or CoOOH precursor having an average particle size (D 50 ) of the primary particles of 3,000 ppm or more and a primary particle size of 15 μm or more.
상기 전구체 형성 용액을 반응기에 투입하고, 킬레이팅제 및 염기성 수용액을 첨가하여 공침 반응을 통해 도핑 원소가 3,000ppm 이상 도핑되고, 1차 입자의 평균 입경(D50)이 15㎛ 이상인 Co3O4 또는 CoOOH 전구체를 제조할 수 있다. The precursor solution was added to the reactor and form, doped with the co-precipitation reaction by adding a chelating agent and aqueous base element is doped more than 3,000ppm, 1 average particle diameter of primary particles (D 50) is less than 15㎛ Co 3 O 4 Or a CoOOH precursor can be prepared.
상기 킬레이팅제로는 NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, 또는 NH4CO3 등을 들 수 있으며, 이들 중 1종 단독 또는 2종 이상의 혼합물이 사용될 수 있다. 또, 상기 킬레이팅제는 수용액의 형태로 사용될 수도 있으며, 이때 용매로는 물, 또는 물과 균일하게 혼합 가능한 유기용매(구체적으로, 알코올 등)와 물의 혼합물이 사용될 수 있다.Examples of the chelating agent include NH 4 OH, (NH 4 ) 2 SO 4 , NH 4 NO 3 , NH 4 Cl, CH 3 COONH 4 , and NH 4 CO 3 . The above mixture may be used. The chelating agent may be used in the form of an aqueous solution. As the solvent, water or a mixture of water and an organic solvent (specifically, alcohol or the like) that can be mixed with water and water may be used.
상기 염기성 화합물은 NaOH, KOH 또는 Ca(OH)2 등과 같은 알칼리 금속 또는 알칼리 토금속의 수산화물, 또는 이들의 수화물일 수 있으며, 이들 중 1종 단독 또는 2종 이상의 혼합물이 사용될 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. 이때, 상기 염기성 수용액의 농도는 2M 내지 10M일 수 있다.The basic compound may be a hydroxide of an alkali metal or an alkaline earth metal such as NaOH, KOH or Ca (OH) 2 , or a hydrate thereof, and either one of them or a mixture of two or more of them may be used. The basic compound may also be used in the form of an aqueous solution. As the solvent, water or a mixture of water and an organic solvent (specifically, alcohol or the like) which can be uniformly mixed with water may be used. At this time, the concentration of the basic aqueous solution may be 2M to 10M.
상기 양극 활물질 전구체의 제조를 위한 공침 반응은, pH가 pH 10 내지 pH 12인 조건에서 수행될 수 있다. pH가 상기한 범위를 벗어날 경우, 제조되는 양극 활물질 전구체의 크기를 변화시키거나 입자 쪼개짐을 유발할 우려가 있다. 보다 구체적으로는 pH 11 내지 pH 12의 조건에서 수행될 수 있다. 상기와 같은 pH 조절은 염기성 수용액의 첨가를 통해 제어될 수 있다.The coprecipitation reaction for the production of the cathode active material precursor may be carried out at a pH of from 10 to 12. If the pH is out of the above range, there is a possibility that the size of the cathode active material precursor to be produced is changed or the particle cleavage is caused. More specifically, at a pH of 11 to a pH of 12. Such pH control can be controlled through the addition of a basic aqueous solution.
상기 양극 활물질 전구체의 제조를 위한 공침 반응은 질소 등의 비활성 분위기하에서, 30℃ 내지 80℃의 온도 범위에서 수행될 수 있다. 상기 반응시 반응 속도를 증가시키기 위하여 교반 공정이 선택적으로 수행될 수 있으며, 이때 교반 속도는 100rpm 내지 2000rpm일 수 있다.The coprecipitation reaction for the production of the cathode active material precursor may be performed in an inert atmosphere such as nitrogen at a temperature ranging from 30 ° C to 80 ° C. In order to increase the reaction rate during the reaction, a stirring process may be selectively performed, wherein the stirring speed may be from 100 rpm to 2000 rpm.
상기 공침 반응의 결과로 도핑 원소가 과량 도핑된 1차 입자의 Co3O4 또는 CoOOH 전구체가 침전된다. 상기 전구체에 도핑된 도핑 원소의 함량은 3,000ppm 이상, 보다 바람직하게는 4,000ppm 이상일 수 있다. 상기와 같이 전구체 도핑함으로써 도핑 원소를 고함량으로 도핑할 수 있다. 또한, 이와 같이 제조된 전구체는 도핑 원소가 양극 활물질 전구체 입자의 중심부터 표면까지 농도 구배 없이 균일하게 도핑될 수 있다.As a result of the coprecipitation reaction, the Co 3 O 4 or CoOOH precursor of the primary particles in which the doping element is excessively doped is precipitated. The content of the doping element doped in the precursor may be 3,000 ppm or more, more preferably 4,000 ppm or more. By doping the precursor as described above, the doping element can be doped with a high content. In addition, the precursor thus prepared can be uniformly doped with the doping element without any concentration gradient from the center of the precursor particle of the cathode active material to the surface thereof.
또한, 전구체 제조시 공침 반응 시간을 조절하여 도핑 전구체의 입자 사이즈를 용이하게 조절할 수 있기 때문에 고함량의 도핑을 하면서도 전구체 사이즈를 용이하게 키울 수 있다. 상기 공침 반응 시간은 10 내지 40시간일 수 있으며, 보다 바람직하게는 10 내지 30시간일 수 있다. 이와 같이 공침 시간을 조절하여 1차 입자의 평균 입경(D50)이 15㎛ 이상인 Co3O4 또는 CoOOH 전구체를 형성할 수 있다.In addition, since the particle size of the doping precursor can be easily controlled by controlling the coprecipitation reaction time in the production of the precursor, the size of the precursor can easily be raised while doping with a high content. The coprecipitation reaction time may be 10 to 40 hours, more preferably 10 to 30 hours. Thus, the Co 3 O 4 or CoOOH precursor having an average particle size (D 50 ) of the primary particles of 15 μm or more can be formed by adjusting the coprecipitation time.
상기 침전된 Co3O4 또는 CoOOH 전구체에 대해서는 통상의 방법에 따라 분리 후, 건조 공정이 선택적으로 수행될 수 있으며, 이때 상기 건조 공정은 110℃ 내지 400℃에서 15 내지 30시간 수행될 수 있다.The precipitated Co 3 O 4 or CoOOH precursor may be selectively subjected to separation and drying processes according to a conventional method, and the drying process may be performed at 110 ° C. to 400 ° C. for 15 to 30 hours.
또한, 본 발명은 상기와 같이 과량 도핑된 대입자의 전구체를 사용하여 제조된 양극 활물질을 제공한다. 본 발명의 과량 도핑된 1차 입자인 대입자의 전구체를 사용하여 양극 활물질을 제조함으로써, 과량의 도핑 원소를 함유하며, 1차 입자의 평균 입경이 큰 대입자의 양극 활물질을 제조할 수 있다.Further, the present invention provides a cathode active material prepared using a precursor of an overdoped bulk as described above. By preparing the cathode active material using the large-doped primary particles of the present invention as the large-doped primary particles, it is possible to prepare a large-volume cathode active material containing an excessive amount of the doping element and having a large average particle diameter of the primary particles.
구체적으로, 본 발명의 이차저지용 양극 활물질은 리튬 코발트계 산화물의 1차 입자를 포함하며, 상기 1차 입자는 도핑 원소를 2,500ppm 이상 함유하고, 상기 1차 입자의 평균 입경(D50)이 15㎛ 이상이다.Specifically, the cathode active material for secondary prevention of the present invention contains primary particles of lithium cobalt oxide, the primary particles contain 2,500 ppm or more of the doping element, the average particle diameter (D 50 ) of the primary particles is 15 mu m or more.
만약, 1차 입자가 응집된 2차 입자 형태의 전구체를 사용하는 경우, 소성 과정에서 고함량 도핑 원소의 입자 성장 방해 작용으로 인해 15㎛ 이상의 1차 입자를 갖는 양극 활물질을 제조하기 어렵다. 특히, 도핑 원소 Al의 경우, 다른 도핑 원소(예를 들면, Mg)에 비하여 특히 입자 성장 방해 작용이 크기 때문에, 본 발명과 같이 고함량 도핑되면서 대입자인 전구체를 제조한 후 이를 사용하여 양극 활물질을 제조하는 것이 보다 바람직할 수 있다. If a precursor in the form of a secondary particle in which primary particles are aggregated is used, it is difficult to prepare a cathode active material having primary particles of 15 mu m or more due to the grain growth inhibition action of the high-dose doping element during the firing process. Particularly, in the case of the doping element Al, since the particle growth inhibiting action is particularly large as compared with other doping elements (for example, Mg), the precursor which is a substituent is produced by doping with a high content as in the present invention, It may be more preferable to produce it.
본 발명은 상기와 같이 도핑 원소를 3,000ppm 이상 함유하고, 1차 입자의 평균 입경(D50)이 15㎛ 이상인 전구체를 사용하여 제조되기 때문에, 소성 온도 증가 및 리튬 투입량의 증가 없이도 도핑 원소가 2,500ppm 이상 함유되고, 1차 입자의 평균 입경(D50)이 15㎛ 이상인 양극 활물질을 제조할 수 있다.Since the present invention is produced by using a precursor containing 3,000 ppm or more of the doping element and having an average particle diameter (D 50 ) of the primary particles of 15 μm or more as described above, the doping element is 2,500 ppm or more and an average particle diameter (D 50 ) of the primary particles of 15 탆 or more can be produced.
본 발명의 양극 활물질은 리튬 코발트계 산화물의 1차 입자로 구성된다. The cathode active material of the present invention is composed of primary particles of lithium cobalt oxide.
본 발명의 양극 활물질은 상기 1차 입자의 평균 입경(D50)이 15㎛ 이상이 되도록 하며, 보다 바람직하게는 상기 1차 입자의 평균 입경(D50)이 17㎛ 이상일 수 있다. 상기 양극 활물질의 1차 입자의 평균 입경(D50)이 15㎛ 이상을 만족함으로써 전지 용량, 에너지 밀도 및 수명 특성을 향상시킬 수 있으며, 특히, 상기 평균 입경(D50) 15㎛ 이상의 대입자 양극 활물질과 소입자의 양극 활물질을 일정 비율로 혼합하여 양극의 압축 밀도를 현저히 증가시켜 전지 용량을 증가시킬 수 있다.In the cathode active material of the present invention, the average particle diameter (D 50 ) of the primary particles is 15 μm or more, and more preferably the average particle diameter (D 50 ) of the primary particles is 17 μm or more. It is possible to improve the battery capacity, energy density and lifetime characteristics by satisfying the average particle size (D 50 ) of the primary particles of the cathode active material of 15 탆 or more. In particular, when the average particle diameter (D 50 ) The capacity of the battery can be increased by significantly increasing the compression density of the anode by mixing the active material with the cathode active material of the small particle at a certain ratio.
또한, 본 발명의 양극 활물질은 상기 1차 입자가 도핑 원소를 2,500ppm 이상 함유하며, 보다 바람직하게는 도핑 원소를 3,000ppm 이상 함유할 수 있다. 상기 양극 활물질을 제조할 때, 리튬 소스가 더 첨가되기 때문에 상기 양극 활물질에 함유된 도핑 원소의 함량 비율(ppm)보다 양극 활물질의 도핑 원소의 함량 비율(ppm)가 다소 감소될 수 있다. 상기 양극 활물질의 1차 입자가 도핑 원소를 2,500ppm 미만으로 함유할 경우, 리튬 코발트계 산화물 양극 활물질의 구조 안정성을 확보하기 어려우며, 특히, 4.5V 이상의 고전압 하에서 구조 안정성이 낮아져 상온 및 고온 수명 특성 등의 전지 특성이 저하되는 문제가 있다.In the cathode active material of the present invention, the primary particles may contain a doping element in an amount of 2,500 ppm or more, more preferably 3,000 ppm or more in a doping element. Since the lithium source is further added in the production of the cathode active material, the content ratio (ppm) of the doping element of the cathode active material may be somewhat reduced compared with the content ratio (ppm) of the doping element contained in the cathode active material. When the primary particles of the cathode active material contain less than 2,500 ppm of the doping element, it is difficult to secure the structural stability of the lithium cobalt oxide cathode active material. In particular, the structural stability is lowered at a high voltage of 4.5 V or more, There is a problem that battery characteristics of the battery are deteriorated.
상기 도핑 원소는 Al, Ti, Mn, Zr, Mg, Nb, Ca, F 및 Ni로 이루어진 군에서 선택된 적어도 1종 이상일 수 있으며, 보다 바람직하게는 Al일 수 있다. 도핑 원소 Al의 경우, 다른 도핑 원소(예를 들면, Mg)에 비하여 특히 입자 성장 방해 작용이 크기 때문에, 본 발명과 같이 고함량 도핑되면서 대입자인 전구체를 제조한 후 이를 사용하여 양극 활물질을 제조하는 것이 보다 바람직할 수 있다. The doping element may be at least one or more selected from the group consisting of Al, Ti, Mn, Zr, Mg, Nb, Ca, F and Ni, and more preferably Al. In the case of the doping element Al, since the grain growth inhibiting effect is particularly large as compared with other doping elements (for example, Mg), the precursor which is a substituent is produced with a high content of doping as in the present invention, May be more preferable.
상기와 같이 전구체 제조시 도핑 원소를 도핑한 양극 활물질 전구체를 사용하여 제조된 양극 활물질은 상기 도핑 원소가 양극 활물질 입자의 1차 입자 내에서 일정한 농도를 가질 수 있다. 또한, 상기 양극 활물질의 1차 입자는, 입자의 중심으로부터 표면까지의 반직경 중 중심측 50%에 해당하는 중심부에, 상기 도핑 원소의 전체 함량 중 50% 이상이 함유될 수 있다. In the cathode active material prepared using the cathode active material precursor doped with the doping element in the production of the precursor as described above, the doping element may have a constant concentration in the primary particles of the cathode active material particle. The primary particles of the positive electrode active material may contain 50% or more of the entire content of the doping element in the central portion corresponding to 50% of the center of the radius of the particle from the center to the surface.
상기 리튬 코발트계 산화물은 리튬과 리튬을 제외한 금속원소(Co, M 등)의 몰비(리튬/금속원소(Co, M 등)의 몰비)가 0.98 내지 1.1일 수 있다.The lithium cobalt oxide may have a molar ratio (molar ratio of lithium / metal element (Co, M, etc.)) of metal elements (Co, M, etc.) other than lithium to lithium of 0.98 to 1.1.
또한, 본 발명의 일 실시예에 따른 양극 활물질은 상기 리튬 코발트계 산화물의 입자 표면에 표면층을 더 포함하며, 상기 표면층은 Mg, Ti, Fe, Cu, Ca, Ba, Sn, Sb, Na, Z, Si, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Sc, Ce, Pr, Nd, Gd, Dy, Yb, Er, Co, Al, Ga 및 B로 이루어진 군에서 선택된 적어도 1종 이상의 산화물을 포함할 수 있다. The cathode active material according to an embodiment of the present invention may further include a surface layer on the particle surface of the lithium cobalt oxide and the surface layer may include Mg, Ti, Fe, Cu, Ca, Ba, Sn, Sb, At least one selected from the group consisting of Si, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Sc, Ce, Pr, Nd, Gd, Dy, Yb, Er, Co, One or more oxides.
다음으로, 본 발명의 양극 활물질의 제조방법을 설명한다.Next, a method for producing the positive electrode active material of the present invention will be described.
본 발명의 상기 양극 활물질은, 상기 본 발명의 양극 활물질 전구체 및 리튬 소스를 혼합하고 소성하여, 도핑 원소가 2,500ppm 이상 함유되고, 1차 입자의 평균 입경(D50)이 15㎛ 이상인 리튬 코발트계 산화물을 형성한다.The cathode active material of the present invention is obtained by mixing and firing a cathode active material precursor and a lithium source of the present invention to prepare a lithium cobalt-based compound having a doping element content of 2,500 ppm or more and having an average particle diameter (D 50 ) To form oxides.
상기 리튬 소스로는 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.As the lithium source, a lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide or oxyhydroxide may be used, and it is not particularly limited as long as it can be dissolved in water. Specifically, the lithium source material may be Li 2 CO 3 , LiNO 3 , LiNO 2 , LiOH, LiOH 揃 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 Etc., and any one or a mixture of two or more of them may be used.
또, 상기 리튬 소스의 사용량은 최종 제조되는 리튬 코발트계 산화물에서의 리튬과, 리튬을 제외한 금속원소(Co 등)의 함량에 따라 결정될 수 있으며, 구체적으로는 최종 제조되는 리튬 코발트계 산화물이, 리튬과 리튬을 제외한 금속원소의 몰비(리튬/금속원소의 몰비)가 0.98 내지 1.1이 되도록 하는 양으로 사용될 수 있다.The amount of the lithium source to be used may be determined depending on the content of lithium (Li) and the metal element (Co, etc.) other than lithium in the finally produced lithium cobalt oxide. Specifically, the lithium cobalt- And the molar ratio of the metal element other than lithium (molar ratio of lithium / metal element) is from 0.98 to 1.1.
한편, 상기 전구체 및 리튬 소스 혼합시, 소결제가 선택적으로 더 첨가될 수 있다. 상기 소결제로는 구체적으로 NH4F, NH4NO3, 또는 (NH4)2SO4과 같은 암모늄 이온을 함유한 화합물; B2O3 또는 Bi2O3과 같은 금속산화물; 또는 NiCl2 또는 CaCl2과 같은 금속할로겐화물 등을 들 수 있으며, 이들 중 어느 하나 또는 둘 이상의 혼합물이 사용될 수 있다. 상기 소결제는 전구체 1 몰에 대하여 0.01 내지 0.2 몰의 함량으로 사용될 수 있다. 상기 소결제의 함량이 0.01 몰 미만으로 지나치게 낮으면 양극 활물질 전구체의 소결 특성 향상 효과가 미미할 수 있고, 또 소결제의 함량이 0.2 몰을 초과하여 지나치게 높으면, 과량의 소결제로 인해 양극 활물질로서의 성능 저하 및 충방전 진행시 전지의 초기 용량이 저하될 우려가 있다.On the other hand, when the precursor and the lithium source are mixed, a sintering agent may be optionally added. The sintering agent specifically includes a compound containing an ammonium ion such as NH 4 F, NH 4 NO 3 , or (NH 4 ) 2 SO 4 ; Metal oxides such as B 2 O 3 or Bi 2 O 3 ; Or metal halides such as NiCl 2 or CaCl 2, and any one or a mixture of two or more of them may be used. The sintering may be used in an amount of 0.01 to 0.2 mol based on 1 mol of the precursor. If the content of the sintering agent is less than 0.01 mol, the effect of improving the sintering property of the cathode active material precursor may be insignificant. If the content of the sintering agent is excessively high, the excessive sintering agent may deteriorate the performance of the cathode active material And there is a possibility that the initial capacity of the battery is lowered during the charge / discharge process.
또, 상기 전구체 및 리튬 소스 혼합시, 수분제거제가 선택적으로 더 첨가될 수도 있다. 구체적으로 상기 수분제거제로는 구연산, 주석산, 글리콜산 또는 말레인산 등을 들 수 있으며, 이들 중 어느 하나 또는 둘 이상의 혼합물이 사용될 수 있다. 상기 수분제거제는 전구체 1몰에 대하여 0.01 내지 0.2몰의 함량으로 사용될 수 있다.Further, at the time of mixing the precursor and the lithium source, a moisture removing agent may be optionally added. Specifically, examples of the moisture removing agent include citric acid, tartaric acid, glycolic acid, and maleic acid, and any one or a mixture of two or more thereof may be used. The moisture scavenger may be used in an amount of 0.01 to 0.2 mol based on 1 mol of the precursor.
상기 소성은 900℃ 내지 1,100℃에서 수행될 수 있으며, 보다 바람직하게는 1,000 내지 1,050℃에서 수행될 수 있다. 상기 소성 온도가 900℃ 미만이면 미반응 원료물질의 잔류로 인해 단위 무게당 방전 용량의 저하, 사이클 특성의 저하 및 작동 전압의 저하 우려가 있고, 1,100℃를 초과하면 부반응물의 생성으로 인해 단위무게당 방전용량의 저하, 사이클 특성의 저하 및 작동 전압의 저하 우려가 있다.The firing may be performed at 900 ° C to 1,100 ° C, and more preferably 1,000 to 1,050 ° C. If the calcination temperature is less than 900 ° C., there is a fear that the discharge capacity per unit weight, the cycle characteristics, and the operating voltage may decrease due to the residual unreacted raw material. If the calcination temperature is more than 1,100 ° C., There is a fear of lowering the discharge capacity per unit time, lowering the cycle characteristics, and lowering the operating voltage.
상기 소성은 공기나 산소 등의 산화성 분위기나, 질소 혹은 수소가 포함된 환원성 분위기에서 5시간 내지 30시간 수행될 수 있다. The calcination may be performed in an oxidizing atmosphere such as air or oxygen or a reducing atmosphere containing nitrogen or hydrogen for 5 to 30 hours.
한편, 상기 제조된 리튬 코발계 산화물의 입자 표면에 무기 산화물을 포함하는 표면층을 더 형성할 수 있다.On the other hand, a surface layer containing an inorganic oxide may be further formed on the surface of the lithium co-based oxide thus produced.
상기 표면층은 Mg, Ti, Fe, Cu, Ca, Ba, Sn, Sb, Na, Z, Si, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Sc, Ce, Pr, Nd, Gd, Dy, Yb, Er, Co, Al, Ga 및 B로 이루어진 군에서 선택된 적어도 1종 이상의 산화물을 포함할 수 있으며, 상기 표면층을 형성하는 원소를 포함하는 코팅 물질을 혼합하고, 열처리하여 표면층을 형성할 수 있다.The surface layer may include at least one of Mg, Ti, Fe, Cu, Ca, Ba, Sn, Sb, Na, Z, Si, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, And at least one kind of oxide selected from the group consisting of Gd, Dy, Yb, Er, Co, Al, Ga and B is mixed with the coating material containing the element forming the surface layer, Can be formed.
상기와 같이 제조된 리튬 코발트 산화물의 양극 활물질은 도핑 원소를 과량 도핑하여 고전압 하에서도 구조 안정성을 가지면서도, 도핑 원소에 의한 입자 성장 방해 문제를 해결하여 1차 입자의 평균 입경(D50) 15㎛ 이상의 대입자로 제조될 수 있다. 따라서, 상기 양극 활물질은 4.5V 이상의 고전압 이차전지에 활용 가능하며, 고용량을 구현하는 동시에 수명 특성을 현저히 개선할 수 있다.The cathode active material of lithium cobalt oxide prepared as described above over-doped the doping element to solve the grain growth inhibition problem caused by the doping element while having the structural stability under high voltage, so that the average particle diameter (D 50 ) of the primary particles was 15 탆 Or more. Therefore, the cathode active material can be used for a high-voltage secondary battery of 4.5V or higher, and can realize a high capacity and significantly improve lifetime characteristics.
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 and a lithium secondary battery for 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 활물질 층을 포함한다.Specifically, the positive electrode includes a positive electrode collector and a positive electrode active material layer formed on the positive electrode 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. 또, 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 anode, the cathode current collector is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and for example, a metal such as stainless steel, aluminum, nickel, titanium, sintered carbon, , Nickel, titanium, silver, or the like may be used. In addition, the cathode current collector may have a thickness of 3 to 500 탆, and fine unevenness may be formed on the surface of the cathode current collector to increase the adhesive force of the cathode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.
또, 상기 양극 활물질 층은 앞서 설명한 양극 활물질과 함께, 도전재 및 바인더를 포함할 수 있다.In addition, the cathode active material layer may include a conductive material and a binder together with the cathode active material described above.
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 위스키; 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 양극활물질층 총 중량에 대하여 1 내지 30 중량%로 포함될 수 있다.At this time, the conductive material is used for imparting conductivity to the electrode. The conductive material can be used without particular limitation as long as it has electron conductivity without causing chemical change. Specific examples thereof 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 powder or metal fibers such as copper, nickel, aluminum and silver; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; And polyphenylene derivatives. These may be used alone or in admixture of two or more. The conductive material may be typically contained in an amount of 1 to 30% by weight based on the total weight of the cathode 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 adhesion between the positive electrode active material and the positive electrode collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose ), Starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, and various copolymers thereof. One kind or a mixture of two or more kinds of them may be used. The binder may be included in an amount of 1 to 30% by weight based on the total weight of the cathode 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 활물질 층 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 that the positive electrode active material described above is used. Specifically, the composition for forming a cathode active material layer containing the above-mentioned cathode active material and optionally a binder and a conductive material may be coated on the cathode current collector, followed by drying and rolling. At this time, the types and contents of the cathode 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 양극활물질, 도전재 및 바인더를 용해 또는 분산시키고, 이후 양극제조를 위한 도포시 우수한 두께 균일도를 나타낼 수 있는 점도를 갖도록 하는 정도면 충분하다.Examples of the solvent include dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, and the like. Water and the like, and one kind or a mixture of two or more kinds can be used. The amount of the solvent to be used is sufficient to dissolve or disperse the cathode active material, the conductive material and the binder in consideration of the coating thickness of the slurry and the yield of the slurry, and then to have a viscosity capable of exhibiting excellent thickness uniformity Do.
또, 다른 방법으로, 상기 양극은 상기 양극 활물질 층 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 produced by casting the composition for forming the positive electrode active material layer on a separate support, then peeling off the support from the support, and laminating the obtained film 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, there is provided an electrochemical device including the anode. The electrochemical device may be specifically 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. Specifically, the lithium secondary battery includes a positive electrode, a negative electrode disposed opposite to the positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, as described above. The lithium secondary battery may further include a battery container for storing the positive electrode, the negative electrode and the electrode assembly of 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 음극활물질 층을 포함한다.In the lithium secondary battery, the negative electrode includes a negative electrode current collector and a negative electrode active material layer disposed 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 음극활물질의 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 changes in the battery. For example, the negative electrode current collector may be formed on the surface of copper, stainless steel, aluminum, nickel, titanium, sintered carbon, Carbon, nickel, titanium, silver or the like, aluminum-cadmium alloy, or the like may be used. In addition, the negative electrode collector may have a thickness of 3 to 500 탆, and similarly to the positive electrode collector, fine unevenness may be formed on the surface of the collector to enhance the binding force of the negative electrode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.
상기 음극 활물질 층은 음극 활물질과 함께 선택적으로 바인더 및 도전재를 포함한다. 상기 음극 활물질 층은 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 negative electrode active material layer may be formed by applying and drying a composition for forming a negative electrode including a negative electrode active material on the negative electrode collector and, optionally, a binder and a conductive material, or by casting the composition for forming a negative electrode on a separate support , And a film obtained by peeling from the support may be laminated on the negative electrode 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; SiOx(0 < x < 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 negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples thereof 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 alloys, Sn alloys or Al alloys; Metal oxides capable of doping and dedoping lithium such as SiO x (0 <x <2), SnO 2 , vanadium oxide, and lithium vanadium oxide; Or a composite containing the metallic compound and the carbonaceous material such as Si-C composite or Sn-C composite, and any one or a mixture of two or more thereof may be used. Also, a metal lithium thin film may be used as the negative electrode active material. The carbon material may be both low-crystalline carbon and high-crystallinity carbon. Examples of the low-crystalline carbon include soft carbon and hard carbon. Examples of the highly crystalline carbon include natural graphite, artificial graphite, artificial graphite or artificial graphite, Kish graphite graphite, pyrolytic carbon, mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches and petroleum or coal tar coke derived cokes).
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 anode.
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.Meanwhile, in the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a moving path of lithium ions. The separator can be used without any particular limitation as long as it is used as a separator in a lithium secondary battery. Particularly, It is preferable to have a low resistance and an excellent ability to impregnate the electrolyte. Specifically, porous polymer films such as porous polymer films made of polyolefin-based polymers such as ethylene homopolymers, propylene homopolymers, ethylene / butene copolymers, ethylene / hexene copolymers and ethylene / methacrylate copolymers, May be used. Further, a nonwoven fabric made of a conventional porous nonwoven fabric, for example, glass fiber of high melting point, polyethylene terephthalate fiber, or the like may be used. In order to secure heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymer material may be used, and may be optionally used as a single layer or a multilayer 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. Examples of the electrolyte used in the present invention include an organic-based liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, and a molten inorganic electrolyte that can be used in the production of a lithium secondary battery. It is not.
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), 메틸에틸카보네이트(methylethylcarbonate, MEC), 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 높은 이온전도도 및 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 limitation as long as it can act as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, examples of the organic solvent include ester solvents such as methyl acetate, ethyl acetate,? -Butyrolactone and? -Caprolactone; Ether solvents such as dibutyl ether or tetrahydrofuran; Ketone solvents such as cyclohexanone; Aromatic hydrocarbon solvents such as benzene and fluorobenzene; Dimethyl carbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), propylene carbonate PC) and the like; Alcohol solvents such as ethyl alcohol and isopropyl alcohol; R-CN (R is a straight, branched or cyclic hydrocarbon group of C2 to C20, which may contain 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, a carbonate-based solvent is preferable, and a cyclic carbonate (for example, ethylene carbonate or propylene carbonate) having a high ionic conductivity and a high dielectric constant, for example, such as ethylene carbonate or propylene carbonate, For example, 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 electrolytic solution 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 can 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, 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 may be used. The concentration of the lithium salt is preferably in the range of 0.1 to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte has an appropriate conductivity and viscosity, so that it can exhibit excellent electrolyte performance and the lithium ion can effectively move.
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 addition to the electrolyte components, the electrolyte may contain, for example, a haloalkylene carbonate-based compound such as difluoroethylene carbonate or the like, pyridine, triethanolamine, or the like for the purpose of improving lifetime characteristics of the battery, Ethyl phosphite, triethanol amine, cyclic ether, ethylenediamine, glyme, hexametriamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, At least one additive such as benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, The additive may be included in an amount of 0.1 to 5% by weight based on the total weight of the electrolyte.
상기와 같이 본 발명에 따른 양극 활물질을 포함하는 리튬 이차전지는 우수한 방전 용량, 출력 특성 및 용량 유지율을 안정적으로 나타내기 때문에, 휴대전화, 노트북 컴퓨터, 디지털 카메라 등의 휴대용 기기, 및 하이브리드 전기자동차(hybrid electric vehicle, HEV) 등의 전기 자동차 분야 등에 유용하다. As described above, since the lithium secondary battery including the cathode active material according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, it can be used in portable devices such as mobile phones, notebook computers, digital cameras, and hybrid electric vehicles hybrid electric vehicle (HEV)).
이에 따라, 본 발명의 다른 일 구현예에 따르면, 상기 리튬 이차전지를 단위 셀로 포함하는 전지 모듈 및 이를 포함하는 전지팩이 제공된다. According to another embodiment of the present invention, there is provided a battery module including the lithium secondary battery as a unit cell and a battery pack including the same.
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 the battery pack may include a power tool; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); Or a power storage system, as shown in FIG.
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 skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
실시예 1 - 양극 활물질 전구체의 제조Example 1 - Preparation of a cathode active material precursor
60℃로 설정된 회분식 배치(batch)형 5L 반응기에서, CoSO4를 물 중에서 혼합하고, Al(OH)3를 CoSO4 대비 0.5중량%를 더 혼합하여 2M 농도의 전구체 형성 용액을 준비하였다. 전구체 형성 용액이 담겨있는 용기는 반응기로 들어가도록 연결하고, 추가로 25% 농도의 NaOH 수용액과 15% 농도의 NH4OH 수용액을 준비하여 각각 반응기에 연결하였다. 공침 반응기(용량 5L)에 탈이온수 1리터를 넣은 뒤 질소가스를 반응기에 2리터/분의 속도로 퍼징하여 물 속의 용존 산소를 제거하고 반응기 내를 비산화 분위기로 조성하였다. 이후 25% 농도의 NaOH 수용액 10ml를 투입한 후, 60℃ 온도에서 1200rpm의 교반 속도로 교반하며, pH 12.0을 유지하도록 하였다. 이후 상기 전구체 형성 용액을 4ml/min, NaOH 수용액을 1ml/min, NH4OH 수용액을 1ml/min의 속도로 각각 투입하면서 공침 반응을 12시간 동안 진행하여 5,000ppm Al 도핑된 약 15㎛의 Co3O4를 제조하였다. 결과로 형성된 5,000ppm Al 도핑된 Co3O4의 입자를 분리하여 수세 후 120℃의 오븐에서 건조하여 양극 활물질 전구체를 제조하였다. In a batch-type 5 L reactor set at 60 ° C, CoSO 4 was mixed in water, and a solution of 2 M concentration precursor was prepared by further mixing 0.5 wt% of Al (OH) 3 with respect to CoSO 4 . The vessel containing the precursor forming solution was connected to the reactor, and an aqueous 25% NaOH solution and a 15% NH 4 OH aqueous solution were further connected to the reactor. One liter of deionized water was added to the coprecipitation reactor (capacity: 5 L), and nitrogen gas was purged into the reactor at a rate of 2 liters / minute to remove dissolved oxygen in the water and form a non-oxidizing atmosphere in the reactor. Thereafter, 10 ml of a 25% NaOH aqueous solution was added thereto, and the mixture was stirred at a temperature of 60 ° C and a stirring speed of 1200 rpm to maintain a pH of 12.0. After the formation of the precursor solution, 4ml / min, NaOH aqueous solution of 1ml / min, NH 4 OH solution and with each of the input at a rate of 1ml / min co-precipitation reaction to proceed for 12 hours 5,000ppm of Co 3 Al doped about 15㎛ O 4 . The resultant 5,000 ppm Al-doped Co 3 O 4 particles were separated, washed with water and then dried in an oven at 120 ° C to prepare a cathode active material precursor.
실시예 2 - 양극 활물질 전구체의 제조Example 2 - Preparation of a cathode active material precursor
전구체 도핑 시 Al(OH)3를 CoSO4 대비 0.3중량%로 혼합하고, 공침 반응을 12시간 동안 진행하여 3,000ppm Al 도핑된 Co3O4의 전구체(약 15㎛)를 제조한 것을 제외하고는, 실시예 1과 동일하게 실시하여 양극 활물질 전구체를 제조하였다.Except that Al (OH) 3 was doped at 0.3 wt% of CoSO 4 in doping the precursor, and a coprecipitation reaction was conducted for 12 hours to prepare a precursor of AlO 3 -doped Co 3 O 4 (about 15 μm) , And a cathode active material precursor was prepared in the same manner as in Example 1.
실시예Example 3 - 양극 활물질의 제조 3 - Preparation of cathode active material
실시예 1과 같이 제조된 양극 활물질 전구체(5,000ppm Al 도핑된 Co3O4)와, 리튬 소스로서 Li2CO3을 Li/Co 1.035 몰비로 혼합하고, 1,000℃에서 17시간 가량 소성하여 4,500ppm Al이 도핑된 리튬 코발트 산화물을 제조하였다.The cathode active material precursor (5,000 ppm Al-doped Co 3 O 4 ) prepared as in Example 1 and Li 2 CO 3 as a lithium source were mixed at a molar ratio of Li / Co of 1.035 and calcined at 1,000 ° C. for 17 hours to obtain 4,500 ppm Al-doped lithium cobalt oxide was prepared.
실시예Example 4 - 양극 활물질의 제조 4 - Preparation of cathode active material
실시예 2와 같이 제조된 양극 활물질 전구체(3,000ppm Al 도핑된 Co3O4)와, 리튬 소스로서 Li2CO3을 Li/Co 1.035 몰비로 혼합하고, 1,000℃에서 17시간 가량 소성하여 2,500ppm Al이 도핑된 리튬 코발트 산화물을 제조하였다.The cathode active material precursor (3,000 ppm Al-doped Co 3 O 4 ) prepared as in Example 2 and Li 2 CO 3 as a lithium source were mixed at a molar ratio of Li / Co of 1.035 and calcined at 1,000 ° C. for 17 hours to give 2,500 ppm Al-doped lithium cobalt oxide was prepared.
비교예Comparative Example 1 - 양극 활물질 전구체의 제조 1 - Preparation of cathode active material precursor
전구체 도핑 시 Al(OH)3를 CoSO4 대비 0.3중량%로 혼합하고, 공침 반응을 6시간 동안 진행하여 3,000ppm Al 도핑된 Co3O4의 전구체(약 7㎛)를 제조한 것을 제외하고는, 실시예 1과 동일하게 실시하여 양극 활물질 전구체를 제조하였다.Except that Al (OH) 3 was doped in 0.3 wt% of CoSO 4 in the precursor doping and the coprecipitation reaction was carried out for 6 hours to prepare a precursor of 3,000 ppm Al-doped Co 3 O 4 (about 7 μm) , And a cathode active material precursor was prepared in the same manner as in Example 1.
비교예Comparative Example 2 - 양극 활물질 제조 2 - Production of cathode active material
비교예 1과 같이 제조된 양극 활물질 전구체(3,000ppm Al 도핑된 Co3O4)와, 리튬 소스로서 Li2CO3을 Li/Co 1.045 몰비로 혼합하고, 1,020℃에서 20시간 가량 소성하여 2,500ppm Al이 도핑된 리튬 코발트 산화물을 제조하였다.The cathode active material precursor (3,000 ppm Al-doped Co 3 O 4 ) prepared as in Comparative Example 1 and Li 2 CO 3 as a lithium source were mixed at a Li / Co 1.045 molar ratio and calcined at 1,020 ° C. for 20 hours to obtain 2,500 ppm Al-doped lithium cobalt oxide was prepared.
비교예Comparative Example 3 - 양극 활물질 제조 3 - Production of cathode active material
전구체 도핑하지 않은 Co3O4 전구체(약 17㎛)를 사용하고, 소성 시 리튬 소스와 함께 Al(OH)3 3,000ppm을 혼합하여 도핑한 것을 제외하고는, 실시예 1과 동일하게 실시하여 양극 활물질을 제조하였다.Except that a Co 3 O 4 precursor (about 17 탆) not doped with a precursor was used and 3,000 ppm of Al (OH) 3 was mixed with a lithium source during firing to be doped, To prepare an active material.
이와 같이 제조된 양극 활물질은 Al이 표면으로부터 내부로 갈수록 점진적으로 감소하는 농도 구배를 갖고 도핑되었다.The thus prepared cathode active material was doped with a concentration gradient gradually decreasing from the surface to the inside of Al.
비교예Comparative Example 4 - 양극 활물질 제조 4 - Production of cathode active material
5㎛의 1차 입자가 응집된 2차 입자 형태이며, 3,000ppm Al 도핑된 전구체와, 리튬 소스로서 Li2CO3을 Li/Co 1.045 몰비로 혼합하고, 1,020℃에서 20시간 가량 소성하여 2,500ppm Al이 도핑된 리튬 코발트 산화물을 제조하였다.A secondary particle type in which primary particles of 5 mu m were aggregated and a precursor doped with 3,000 ppm of Al and Li 2 CO 3 as a lithium source were mixed at a Li / Co 1.045 molar ratio and calcined at 1,020 ° C. for 20 hours to give 2,500 ppm Al-doped lithium cobalt oxide was prepared.
이와 같이 제조된 양극 활물질은 1차 입자가 12㎛까지는 성장하였으나, Al의 입자 성장 방해 작용으로 인해 그 이상 성장은 이루어지지 않았다.The thus prepared cathode active material was grown up to 12 탆 in primary particle size, but no abnormal growth was caused due to interference of grain growth of Al.
[실험예 1: 양극 활물질 전구체 관찰][Experimental Example 1: Observation of Cathode Active Material Precursor]
상기 실시예 1 및 비교예 1에서 제조된 양극 활물질 전구체 분말을 주사전자현미경(SEM)으로 확대 관찰한 사진을 도 1(실시예 1) 및 도 2(비교예 1)에 나타내었다. 1 (Example 1) and FIG. 2 (Comparative Example 1) show photographs of the cathode active material precursor powder prepared in Example 1 and Comparative Example 1 magnified with a scanning electron microscope (SEM).
도 1 및 도 2를 참조하면, 실시예 1 및 비교예 1에서 제조된 Co3O4의 양극 활물질 전구체는 1차 입자로 이루어져 있으며, 실시예 1(도 1)은 1차 입자가 약 15㎛으로 대입자를 형성하였고, 비교예 1(도 2)는 1차 입자가 약 7㎛으로 소입자를 형성하였다.Referring to FIGS. 1 and 2, the cathode active material precursor of Co 3 O 4 prepared in Example 1 and Comparative Example 1 is composed of primary particles, and Example 1 (FIG. 1) , And Comparative Example 1 (Fig. 2) formed small particles with a primary particle size of about 7 mu m.
[실험예 2: 입자 입경 측정][Experimental Example 2: Particle size measurement]
상기 실시예 1 내지 4 및 비교예 1 내지 2에서 제조된 양극 활물질 전구체 및 양극 활물질의 1차 입자 평균 입경을 입도 분석기(Particle Size Distribution, PSD)로 측정하였고, 그 결과를 하기 표 1에 나타내었다.The average particle diameters of the primary particles of the cathode active material precursor and the cathode active material prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were measured by Particle Size Distribution (PSD), and the results are shown in Table 1 below .
실시예1Example 1 실시예2Example 2 실시예3Example 3 실시예4Example 4 비교예1Comparative Example 1 비교예2Comparative Example 2 비교예4Comparative Example 4
평균 입경(D50)(㎛)Average particle diameter (D 50 ) (탆) 1515 1515 1717 1717 77 1212 1212
상기 표 1을 참조하면, 실시예 1 및 실시예 2는 전구체 1차 입자의 평균 입경(D50)이 15㎛ 이상임을 확인할 수 있었으며, 상기 실시예 1 및 실시예 2의 전구체를 각각 사용하여 양극 활물질을 제조한 실시예 3 및 실시예 4의 경우, 소성 온도 및 리튬 투입량을 증가시키지 않고도 Al이 2,500ppm 이상 고함량 도핑되고, 1차 입자 평균 입경(D50)이 15㎛ 이상 대입자인 양극 활물질을 제조할 수 있었다.Referring to Table 1, it was confirmed that the average particle diameter (D 50 ) of the primary particles of the precursor was 15 μm or more in Example 1 and Example 2, and the precursors of Example 1 and Example 2 were used, In the case of Examples 3 and 4 in which the active material was prepared, Al was doped with a high content of not less than 2,500 ppm without increasing the firing temperature and the amount of lithium input, and the cathode active material having a primary particle average particle diameter (D 50 ) . &Lt; / RTI &gt;
반면에, 비교예 1은 전구체 1차 입자의 평균 입경(D50)이 7㎛임을 확인할 수 있었으며, 상기 비교예 1의 전구체를 사용하여 양극 활물질을 제조한 비교예 2의 경우, 고함량으로 도핑된 도핑 원소 Al에 의해서 입자 성장이 방해되어 소성 온도 및 리튬 투입량을 증가시켰음에도 불구하고, 1차 입자 평균 입경(D50)이 12㎛로 밖에 성장되지 않아 대입자의 양극 활물질을 제조할 수 없었다.On the other hand, in Comparative Example 1, it was confirmed that the average particle diameter (D 50 ) of the primary particles of the precursor was 7 μm, and in Comparative Example 2 in which the cathode active material was prepared using the precursor of Comparative Example 1, The average particle diameter (D 50 ) of the primary particles was only 12 탆, and the cathode active material could not be prepared.
한편, 1차 입자가 응집된 2차 입자 형태의 전구체를 사용하여 제조한 비교예 4의 경우, 1차 입자가 12㎛까지는 성장하였으나, Al의 입자 성장 방해 작용으로 인해 그 이상 성장은 이루어지지 않았다.On the other hand, in the case of Comparative Example 4 produced using the secondary particle type precursor in which the primary particles aggregated, the primary particles were grown up to 12 탆, but no abnormal growth was caused due to the grain growth inhibiting action of Al .
[실험예 3: 전지 성능 평가][Experimental Example 3: Evaluation of cell performance]
실시예 3 내지 4 및 비교예 2 내지 4에서 제조된 양극 활물질을 사용하고, 카본 블랙, PVDF 바인더를 N-메틸피롤리돈 용매 중에 중량비로 96:2:2의 비율로 혼합하여 양극 형성용 조성물을 제조하고, 이를 알루미늄 집전체의 일면에 도포한 후, 130℃에서 건조 후 압연하여, 각각 양극을 제조하였다.Using the cathode active materials prepared in Examples 3 to 4 and Comparative Examples 2 to 4, carbon black and PVDF binder were mixed at a weight ratio of 96: 2: 2 in N-methylpyrrolidone solvent to prepare a composition for anode formation Was coated on one side of the aluminum current collector, dried at 130 캜, and rolled to prepare a positive electrode.
한편, 음극은 리튬 메탈을 사용하였다.On the other hand, lithium metal was used for the cathode.
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/디메틸카보네이트/에틸메틸카보네이트(EC/DMC/EMC의 혼합 부피비=3/4/3)로 이루어진 유기 용매에 1.0M 농도의 리튬헥사플루오로포스페이트(LiPF6)를 용해시켜 제조하였다. A lithium secondary battery was prepared by preparing an electrode assembly between a positive electrode and a negative electrode manufactured as described above through a separator of porous polyethylene, positioning the electrode assembly inside a case, and then injecting an electrolyte into the case. The electrolyte solution was prepared by dissolving 1.0 M lithium hexafluorophosphate (LiPF 6 ) in an organic solvent composed of ethylene carbonate / dimethyl carbonate / ethyl methyl carbonate (mixed volume ratio of EC / DMC / EMC = 3/4/3) Respectively.
상기와 같이 제조된 각 리튬 이차 전지 셀(half cell)에 대해 충방전 실험을 진행하여 용량 및 2.0C/0.1C 율 특성을 측정하였으며, 그 결과를 하기 표 1에 나타내었다.The capacity and 2.0C / 0.1C ratio characteristics of each lithium secondary battery cell (half cell) manufactured as described above were measured and the results are shown in Table 1 below.
또한, 상기와 같이 제조된 각 리튬 이차 전지 셀(half cell)에 대해 각각 25℃ 및 45℃에서 CCCV 모드로 0.5C, 4.55V가 될 때까지 충전하고, 0.05C 조건으로 cut off하였으며, 1.0C의 정전류로 3.0V가 될 때까지 방전하여 50회 충방전을 실시하면서 용량 유지율(Capacity Retention[%])을 측정하였으며, 그 결과를 표 2에 나타내었다.Each lithium secondary battery cell thus prepared was charged at 0.5 C and 4.55 V in a CCCV mode at 25 캜 and 45 캜, cut off at a temperature of 0.05 C, (Capacity Retention [%]) was measured while discharging at a constant current of 3.0 V and performing charge / discharge 50 times. The results are shown in Table 2.
실시예3Example 3 실시예4Example 4 비교예2Comparative Example 2 비교예3Comparative Example 3 비교예 4Comparative Example 4
용량(mAh/g)Capacity (mAh / g) 207207 209209 209209 209209 208208
율특성(%)Rate characteristic (%) 92.892.8 92.592.5 91.791.7 91.891.8 91.591.5
25℃ 50사이클 용량 유지율(%)25 C 50 Cycle Capacity Retention (%) 9696 9595 9292 9393 9292
45℃ 50사이클 용량 유지율(%)45 C 50 Cycle Capacity Retention (%) 9595 9595 9191 9191 9090
표 2를 참조하면, 전구체 1차 입자의 평균 입경(D50)이 7㎛인 비교예 1의 전구체를 사용하여 양극 활물질을 제조한 비교예 2나, 전구체 도핑하지 않고 1차 소성 도핑하여 제조한 비교예 3에 비하여, 본 발명의 실시예에 따라 평균 입경(D50)이 15㎛ 이상인 대입자의 전구체를 각각 사용하여 양극 활물질을 제조한 실시예 3 및 실시예 4의 경우 율 특성이 우수하였으며, 사이클 특성이 우수하였고, 특히 고온 사이클 특성이 현저히 우수하였다. 또한, 비교예 4에 비해서도 실시예 3~4의 전지 성능이 우수하게 나타났다. As shown in Table 2, Comparative Example 2 in which the cathode active material was prepared by using the precursor of Comparative Example 1 having an average particle diameter (D 50 ) of the primary particles of the precursor of 7 μm and Comparative Example 2 in which the cathode active material was prepared by the first- Compared with Comparative Example 3, the rate characteristics were excellent in Examples 3 and 4 in which the positive electrode active material was prepared by using a large number of precursors having an average particle diameter (D 50 ) of 15 μm or more according to the embodiment of the present invention, Cycle characteristics, and especially high-temperature cycle characteristics were remarkably excellent. In addition, the cell performance of Examples 3 to 4 was superior to that of Comparative Example 4.

Claims (21)

  1. Co3O4 또는 CoOOH의 1차 입자를 포함하며,Co 3 O 4 or CoOOH,
    상기 1차 입자는 도핑 원소를 3,000ppm 이상 함유하고,Wherein the primary particles contain at least 3,000 ppm of a doping element,
    상기 1차 입자의 평균 입경(D50)이 15㎛ 이상인 이차전지용 양극 활물질 전구체. Wherein the average particle size (D 50 ) of the primary particles is 15 占 퐉 or more.
  2. 제1항에 있어서,The method according to claim 1,
    상기 1차 입자의 평균 입경(D50)이 17㎛ 이상인 이차전지용 양극 활물질 전구체.Wherein the average particle diameter (D 50 ) of the primary particles is 17 탆 or more.
  3. 제1항에 있어서,The method according to claim 1,
    상기 도핑 원소는 Al, Ti, Mn, Zr, Mg, Nb, Ca, F 및 Ni로 이루어진 군에서 선택된 적어도 1종 이상인 이차전지용 양극 활물질 전구체.Wherein the doping element is at least one selected from the group consisting of Al, Ti, Mn, Zr, Mg, Nb, Ca, F and Ni.
  4. 제1항에 있어서,The method according to claim 1,
    상기 도핑 원소는 Al인 이차전지용 양극 활물질 전구체.Wherein the doping element is Al.
  5. 제1항에 있어서,The method according to claim 1,
    상기 1차 입자는 도핑 원소를 4,000ppm 이상 함유하는 이차전지용 양극 활물질 전구체.Wherein the primary particles contain a doping element in an amount of 4,000 ppm or more.
  6. 제1항에 있어서,The method according to claim 1,
    상기 도핑 원소는 상기 1차 입자 내에서 일정한 농도를 갖는 이차전지용 양극 활물질 전구체.Wherein the doping element has a constant concentration in the primary particle.
  7. 리튬 코발트계 산화물의 1차 입자를 포함하며,A primary particle of a lithium cobalt oxide,
    상기 1차 입자는 도핑 원소를 2,500ppm 이상 함유하고,Wherein the primary particles contain at least 2,500 ppm of a doping element,
    상기 1차 입자의 평균 입경(D50)이 15㎛ 이상인 이차전지용 양극 활물질.Wherein the primary particles have an average particle diameter (D 50 ) of 15 탆 or more.
  8. 제7항에 있어서,8. The method of claim 7,
    상기 1차 입자는, 입자의 중심으로부터 표면까지의 반직경 중 중심측 50%에 해당하는 중심부에, 상기 도핑 원소의 전체 함량 중 50% 이상이 함유된 이차전지용 양극 활물질.Wherein the primary particles contain at least 50% of the total content of the doping element in a central portion corresponding to 50% of the center side of the radius of the particle from the center to the surface.
  9. 제7항에 있어서,8. The method of claim 7,
    상기 1차 입자의 평균 입경(D50)이 17㎛ 이상인 이차전지용 양극 활물질.Wherein the primary particles have an average particle diameter (D 50 ) of 17 탆 or more.
  10. 제7항에 있어서,8. The method of claim 7,
    상기 도핑 원소는 Al, Ti, Mn, Zr, Mg, Nb, Ca, F 및 Ni로 이루어진 군에서 선택된 적어도 1종 이상인 이차전지용 양극 활물질.Wherein the doping element is at least one selected from the group consisting of Al, Ti, Mn, Zr, Mg, Nb, Ca, F and Ni.
  11. 제7항에 있어서,8. The method of claim 7,
    상기 도핑 원소는 Al인 이차전지용 양극 활물질.Wherein the doping element is Al.
  12. 제7항에 있어서,8. The method of claim 7,
    상기 1차 입자는 도핑 원소를 3,000ppm 이상 함유하는 이차전지용 양극 활물질.Wherein the primary particles contain 3,000 ppm or more of a doping element.
  13. 제7항에 있어서,8. The method of claim 7,
    상기 도핑 원소는 상기 1차 입자 내에서 일정한 농도를 갖는 이차전지용 양극 활물질.Wherein the doping element has a constant concentration in the primary particle.
  14. 제7항에 있어서,8. The method of claim 7,
    상기 리튬 코발트계 산화물의 입자 표면에 표면층을 더 포함하며,Further comprising a surface layer on the particle surface of the lithium cobalt oxide,
    상기 표면층은 Mg, Ti, Fe, Cu, Ca, Ba, Sn, Sb, Na, Z, Si, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Sc, Ce, Pr, Nd, Gd, Dy, Yb, Er, Co, Al, Ga 및 B로 이루어진 군에서 선택된 적어도 1종 이상의 산화물을 포함하는 이차전지용 양극 활물질.The surface layer may include at least one of Mg, Ti, Fe, Cu, Ca, Ba, Sn, Sb, Na, Z, Si, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, And at least one oxide selected from the group consisting of Gd, Dy, Yb, Er, Co, Al, Ga and B,
  15. 제7항에 있어서,8. The method of claim 7,
    상기 리튬 코발트계 산화물은, 리튬과 리튬을 제외한 금속원소의 몰비(리튬/금속원소의 몰비)가 0.98 내지 1.1인 이차전지용 양극 활물질.Wherein the lithium cobalt oxide has a molar ratio (molar ratio of lithium / metal element) of metal elements excluding lithium to lithium of 0.98 to 1.1.
  16. 코발트 함유 출발물질 및 도핑 원소 소스를 포함하는 전구체 형성 용액을 마련하는 단계; 및Providing a precursor forming solution comprising a cobalt-containing starting material and a doping element source; And
    상기 전구체 형성 용액을 공침 반응시켜, 도핑 원소가 3,000ppm 이상 함유되고, 1차 입자의 평균 입경(D50)이 15㎛ 이상인 Co3O4 또는 CoOOH의 전구체를 형성하는 단계;Forming a precursor of Co 3 O 4 or CoOOH having an average particle diameter (D 50 ) of the primary particles of not less than 15 μm, the precursor forming solution containing at least 3,000 ppm of a doping element;
    를 포함하는 이차전지용 양극 활물질 전구체의 제조방법.And a cathode active material precursor.
  17. 제16항에 있어서,17. The method of claim 16,
    상기 도핑 원소는 Al, Ti, Mn, Zr, Mg, Nb, Ca, F 및 Ni로 이루어진 군에서 선택된 적어도 1종 이상인 이차전지용 양극 활물질 전구체의 제조방법.Wherein the doping element is at least one selected from the group consisting of Al, Ti, Mn, Zr, Mg, Nb, Ca, F and Ni.
  18. 제16항에 있어서,17. The method of claim 16,
    상기 공침 반응 시간은 10 내지 40시간인 이차전지용 양극 활물질 전구체의 제조방법.Wherein the coprecipitation reaction time is 10 to 40 hours.
  19. 제1항에 따른 양극 활물질 전구체 및 리튬 소스를 혼합하고 소성하여, 도핑 원소가 2,500ppm 이상 함유되고, 1차 입자의 평균 입경(D50)이 15㎛ 이상인 리튬 코발트계 산화물을 형성하는 이차전지용 양극 활물질의 제조방법.A positive electrode active material precursor according to claim 1 and a lithium source are mixed and fired to form a lithium cobalt-based oxide having an average particle size (D 50 ) of primary particles of not less than 15 μm and containing not less than 2,500 ppm of a doping element, A method for producing an active material.
  20. 제7항에 따른 양극 활물질을 포함하는 이차전지용 양극.A positive electrode for a secondary battery comprising the positive electrode active material according to claim 7.
  21. 제20항에 따른 양극을 포함하는 리튬 이차전지.A lithium secondary battery comprising a positive electrode according to claim 20.
PCT/KR2018/011081 2017-09-19 2018-09-19 Cathode active material precursor for secondary battery, cathode active material, and lithium secondary battery comprising same WO2019059654A1 (en)

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