WO2019041788A1 - 一种核壳材料 - Google Patents

一种核壳材料 Download PDF

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WO2019041788A1
WO2019041788A1 PCT/CN2018/079942 CN2018079942W WO2019041788A1 WO 2019041788 A1 WO2019041788 A1 WO 2019041788A1 CN 2018079942 W CN2018079942 W CN 2018079942W WO 2019041788 A1 WO2019041788 A1 WO 2019041788A1
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core
shell
shell material
precursor
material according
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PCT/CN2018/079942
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English (en)
French (fr)
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毕玉敬
刘孟
姜阳
秦银平
王德宇
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中国科学院宁波材料技术与工程研究所
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Publication of WO2019041788A1 publication Critical patent/WO2019041788A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to a core-shell material and belongs to the field of electrode materials.
  • lithium-ion battery As a new green energy source, lithium-ion battery has outstanding advantages such as high energy density, long cycle life, low self-discharge efficiency, no memory effect, and good safety. It has been widely used in electronic products and power car batteries. At present, the challenge of on-board lithium-ion batteries is to improve the cruising range on the premise of ensuring safety, and on the other hand to reduce costs.
  • the positive electrode material is an important component in determining the energy density of a lithium ion battery in a lithium ion battery, and the energy density of the lithium ion battery can be effectively improved by increasing the capacity of the positive electrode material.
  • Nickel-cobalt-manganese-lithium and nickel-cobalt-aluminum silicate-based layered cathode materials are considered to be the most promising cathode materials for on-board lithium batteries due to their high capacity, good rate performance and low price.
  • high nickel ternary materials have problems such as high surface activity and instability in humid air.
  • the currently used improvement method is to coat the surface of the material with an inert substance such as MgO, TiO 2 , Al 2 O 3 (Ultrathin Al 2 O 3 Coatings for Improved Cycling Performance and Thermal Stability of LiNi 0.5 Co 0.2 Mn 0.3 O 2 Cathode.Material Electrochimica Acta 203 (2016) 154-161 and patent "a lithium ion battery and its positive electrode material", publication number: CN102332577A), SiO 2 (High-performance lithium ion batteries using SiO 2 -coated LiNi 0.5 Co 0.2 Mn 0.3 O 2 microspheres as cathodes. Journal of Alloys and Compounds 709 (2017) 708-716).
  • an inert substance such as MgO, TiO 2 , Al 2 O 3 (Ultrathin Al 2 O 3 Coatings for Improved Cycling Performance and Thermal Stability of LiNi 0.5 Co 0.2 Mn 0.3 O 2 Cathode.Material Electrochimica Acta 203 (2016)
  • the principle of coating is to reduce the direct contact between the ternary material and the air and electrolyte, and to inhibit the formation of side reactions on the surface of the ternary material.
  • most of the coating methods are for the processing of the sintered material. Since the coating process usually requires the sintered ternary material to be treated in water or an organic solvent, secondary calcination is required, and the calcination process is inevitable. The local spinel phase will be generated, causing the material capacity to decrease, the cycle to deteriorate, the gas production, and the battery safety hazard.
  • the current coating method has a small coating amount, cannot form a uniform coating layer, and the coating layer material is not electrochemically active, and cannot have lithium ion deintercalation ability, thereby affecting the electrochemical performance of the cathode material.
  • a core-shell material for use in a positive electrode material of a lithium ion battery to provide excellent long-cycle stability of the positive electrode while improving safety and storage stability of the material.
  • the positive electrode material with thick composite coating layer proposed in the invention has simple material preparation process, and has the advantages of easy processing in the process of manufacturing the battery using the material; has good application potential and huge market space.
  • the core material of the core-shell material is at least one selected from the group consisting of compounds having the formula of formula (I) and formula (II);
  • M is at least one selected from the group consisting of metals.
  • M is at least one selected from the group consisting of Cr, Mg, Ga, Ti, Fe, Cu, Sb, Sr, Ca, K, Na, Sn, and Zn.
  • x, y, z, r are independently selected from the range of -0.1 ⁇ x ⁇ 0.2, 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 0.5, 0. ⁇ r ⁇ 0.5.
  • x, y, z, r are independently selected from the following ranges: 0 ⁇ x ⁇ 0.1, 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 0.5, 0 ⁇ r ⁇ 0.5.
  • the shell layer has electrochemical activity and lithium ion transport capability.
  • the shell layer of the core-shell material is selected from at least one of a crystalline phase material and an amorphous phase material;
  • the crystalline phase material is selected from at least one of the compounds having the chemical formulas of formula (III), formula (IV), formula (V), and formula (VI):
  • the amorphous phase material is selected from at least one of the compounds having the chemical formulas of formula (VII), (VIII):
  • the Q is at least selected from the group consisting of Nb, Zr, Ta, Y, Sb, Mo, La, Pb, Bi, In, W, Sn, Ga, Cd, Sc, Ba, V, Cr, Ti, and Zn.
  • the crystalline phase material is uniformly dispersed in the amorphous phase material.
  • the concentration of Ni in the shell layer C Ni shell is smaller than the concentration of Ni in the core C Ni core ;
  • the C Ni core at a certain position in the core (the number of moles of Ni in the core / the sum of the positions of Ni and the number of moles of other metal elements) ⁇ 100%;
  • C Ni housing shell in a position (the number of moles of Ni in the shell of the number of moles of the location / position of the Ni and other metal elements) ⁇ 100%.
  • the core shell material has a shell thickness of from 1 to 500 nm.
  • the core shell material has a shell thickness of 50 to 100 nm.
  • the core shell material has a shell thickness of 100 to 300 nm.
  • the number of layers of the shell layer is from 1 to 50 layers.
  • the number of layers of the shell layer is from 1 to 30 layers.
  • the core shell material comprises at least one surface protective layer outside the shell layer.
  • the surface protective layer is selected from at least one of oxides.
  • the oxide is selected from the group consisting of Al 2 O 3 , MgO, ZrO 2 , ZnO, Y 2 O 3 , Ta 2 O 5 , Cr 2 O 3 , Nb 2 O 5 , Mo 2 O 3 , V 2 O 5 At least one of TiO 2 , Ga 2 O 3 , SrO, BaO, WO 2 , Sb 2 O 5 , SnO, CdO, Bi 2 O 3 , and PbO.
  • a method of preparing the core-shell material comprising at least a multilayer precursor method
  • the structure of the multilayer precursor is: at least one of Ni y Co z Mn 1-yz M 1-yzr (OH) 2 and Ni y Co z Al 1-yz M 1-yzr (OH) 2 inside.
  • the outer layer is in turn an oxide, hydroxide or oxyhydroxide corresponding to Q, and/or an oxide, hydroxide or oxyhydroxide corresponding to N;
  • Q is at least one selected from the group consisting of Nb, Zr, Ta, Y, Sb, Mo, La, Pb, Bi, In, W, Sn, Ga, Cd, Sc, Ba, V, Cr, Ti, and Zn;
  • N is at least one selected from the group consisting of Co, Fe, Ni, and Mn.
  • the precursor P1 in the step (1) is mixed with the solution containing the Q element, the pH of the system is adjusted to 2 to 14, after stirring, washing, separating, and drying, the precursor P2 is obtained;
  • step (3) repeating step (2) a total of n times, n is a positive integer greater than or equal to 1, to obtain a precursor Pn;
  • the precursor Pn obtained in the step (3) is mixed with the solution containing the N element, the pH of the system is adjusted to 7 to 14, after stirring, washing, separating, and drying, the precursor P3 is obtained;
  • the precursor P3 obtained in the step (4) is uniformly mixed with a lithium source, and after sintering, the core-shell material is obtained.
  • the method further comprises the steps of:
  • the core-shell material is in contact with the raw material for preparing the surface protective layer, and is coated;
  • the layer-by-layer coating is performed in a direction away from the core.
  • the pH of the system is adjusted to 7 to 14 as described in the step (1), the step (2), and the step (4), using a solution of an alkali metal hydroxide and/or an aqueous ammonia solution.
  • the alkali metal hydroxide is at least one selected from the group consisting of LiOH, NaOH, and KOH.
  • the stirring in the step (1), the step (2), and the step (4) is stirred for 5 to 24 hours;
  • the dried drying temperature is 50 to 200 °C.
  • the drying has a drying temperature of 80 to 200 °C.
  • the pH of the system is adjusted to a value within a range of 10 to 12.
  • the lithium source in the step (5) is at least one selected from the group consisting of lithium carbonate, lithium hydroxide, lithium chloride, lithium nitrate, and lithium acetate.
  • the sintering in the step (5) is carried out in an oxygen-containing atmosphere.
  • the oxygen-containing atmosphere is selected from the group consisting of air, oxygen, a mixture of oxygen and nitrogen and/or argon, and a mixture of air and nitrogen and/or argon.
  • the sintering in the step (5) is first performed at 400 to 700 ° C for 2 to 16 hours, and then at 700 to 1000 ° C for 10 to 24 hours.
  • the sintering in the step (5) is first performed at 450 to 600 ° C for 4 to 7 hours, and then at 800 to 1000 ° C for 10 to 15 hours.
  • the molar ratio of the precursor P1, P2, Pn or P3 to the lithium source is 1:0.98-1.2;
  • the number of moles of the precursor P1, P2, Pn or P3 is calculated by the sum of the molar amounts of the Ni element, the Co element, the M element, the Al element/Mn element and the metal element in the shell precursor in the core; The number is in terms of the number of moles of lithium contained therein.
  • the preparation method of the precursor in the steps (1) to (4) includes at least one of dry mixing, wet ball milling, and coprecipitation.
  • the method for preparing a core-shell material comprises at least the following steps:
  • Q salt is: Q is Nb, Zr, Ta, Y, Sb, Mo, La, Pb, Bi, In, Any one or a combination of two or more of soluble salts (such as sulfates, nitrates, chlorides, acetates) of W, Sn, Ga, Cd, Sc, Ba, V, Cr, Ti, and Zn.
  • soluble salts such as sulfates, nitrates, chlorides, acetates
  • N salt is a soluble salt such as a sulfate, a nitrate, a chloride or an acetate of Co, Fe, Ni or Mn. Any one or a combination of two or more.
  • the precursor P2 is uniformly mixed with the lithium salt, and the uniformly mixed material is sintered in an oxygen atmosphere to obtain a positive electrode material.
  • the molar ratio of the lithium salt to the precursor is 0.98-1.20
  • the lithium salt is one or more of lithium carbonate, lithium hydroxide, lithium chloride, lithium nitrate and lithium acetate.
  • a protective layer oxide may be added to the surface of the positive electrode material. Specifically, the following steps are taken:
  • step (v) Put the material obtained by the step (iv) sintering into water, stir to form a dispersion, add a solution of the C salt, and simultaneously add the alkali solution to adjust the pH to 5-14, and coat the surface of the sintered material.
  • the hydroxide of layer C was obtained as a positive electrode material having a surface coated with a hydroxide of C. After filtration, calcination was carried out to obtain a positive electrode material having an oxide coated with C on its surface.
  • the C salt is a soluble salt of Al, Mg, Zr, Zn, Y, Ta, Cr, Nb, Mo, V, Ti, Ga, Sr, Ba, W, Sb, Sn, Ga, Cd, Bi, Pb.
  • the alkali solution is one or more of NaOH, LiOH, and KOH.
  • the final pH is controlled at different values depending on the type of salt selected.
  • the calcination temperature is 300-700 ° C, and the calcination atmosphere is air or oxygen.
  • the internal body can be obtained as a nickel-cobalt-manganese/lithium aluminate material, and the composite coating layer can be stabilized in air except for the active material, and the protective layer on the surface is an oxide, which protects the electrode material. .
  • the use of the core-shell material and/or the core-shell material prepared by the method is provided, namely:
  • a positive electrode material for a lithium ion battery comprising the core-shell material and/or a core-shell material prepared according to the method.
  • a lithium ion battery comprising the lithium ion battery cathode material.
  • the positive electrode of the lithium ion battery can be used for a positive electrode material in a lithium ion battery using an organic solvent or an aqueous solution as an electrolyte, and can also be used for a positive electrode material in a lithium ion battery using a solid electrolyte.
  • the preparation method of the lithium ion battery mixing the positive electrode material with the conductive agent acetylene black and the binder polyvinylidene fluoride in a solvent of nitrogen methylpyrrolidone (NMP), and mass ratio of the positive electrode material, the conductive agent and the binder At 85:10:5, the uniformly mixed slurry was coated on an aluminum foil and dried to prepare a positive electrode of a lithium ion battery.
  • NMP nitrogen methylpyrrolidone
  • a new positive electrode material and a preparation method for a thicker composite cladding layer are proposed, and the positive electrode material prepared by the method still has a high discharge capacity, since the first phase has a crystalline phase and an amorphous phase.
  • the thicker composite coating provides excellent long-cycle stability of the positive electrode while improving the safety and storage stability of the material.
  • the positive electrode material with thick composite coating layer proposed in the invention has simple material preparation process, and has the advantages of easy processing during the process of manufacturing the battery using the material. Therefore, the material and its preparation process have good application potential and huge market space.
  • the core-shell material provided by the present application has a high discharge capacity, and a thick composite coating layer having a crystalline phase and an amorphous phase is used for the battery positive electrode material, so that the positive electrode has excellent long cycle stability. At the same time, the safety and storage stability of the material are improved.
  • the core-shell material provided by the present application wherein the shell layer has a composite coating layer composed of an amorphous phase and/or a crystal phase, which effectively suppresses outward diffusion of a portion of the nickel of the inner host material, and has a low nickel surface. Applied to the electrode material, it can overcome the defects in the prior art that are easily reduced to affect performance.
  • the core-shell material provided by the present application has an electrochemical activity and a lithium ion transport capability, and the electrode material can block the direct contact between the electrode material and the electrolyte, reduce side reactions inside the battery, and improve safety performance; At the same time, since the shell layer has lithium ion transport capability, it is possible to finitely reduce the impedance increase during battery cycling.
  • the thickness of the shell material of the core-shell material provided by the present application is thicker than the conventional method, between 1-500 nm; the material can work stably under high voltage, and the number of cycles is more than that of ordinary materials, and the lithium ion battery using the cathode material is used. It has a long practical life; it has high stability in wet air and the material is easy to process.
  • Example 1 is a topographical view of a precursor P1 prepared in Example 11.
  • Example 2 is a topographical view of the precursor P2 prepared in Example 12.
  • Example 4 is a topographical view of the precursor P4 prepared in Example 1.
  • Figure 5 is a topographical view of the preparation of the precursor P5 in Example 2.
  • Figure 6 is a topographical view of the preparation of precursor P6 in Example 3.
  • Fig. 7 is a topographical view showing the preparation of the precursor P7 in Example 4.
  • Figure 8 is a topographical view of the preparation of precursor P8 in Example 5.
  • Figure 9 is a topographical view of the preparation of precursor P9 in Example 6.
  • Figure 10 is a topographical view of the preparation of the precursor P10 in Example 7.
  • Figure 11 is a topographical view of the preparation of core shell material 2 # in Example 2.
  • Figure 12 is a topographical view of the preparation of the core-shell material 4 # in Example 4.
  • Figure 13 is a topographical view of the preparation of the core-shell material 7 # in Example 7.
  • Figure 14 is a cross-sectional elemental distribution diagram of the precursor P6 particles prepared in Example 3.
  • FIG 15 is a core-shell material prepared in Example # 33 particle cross-sectional view of an element distribution.
  • Figure 16 is a transmission electron micrograph of the core shell material 11 # prepared in Example 11.
  • Figure 17 is a transmission electron micrograph of the core shell material 2 # prepared in Example 2.
  • Figure 18 is a transmission electron micrograph of the core shell material 3 # prepared in Example 3.
  • Figure 19 is a comparison of X-ray diffraction of core shell materials 11 # , 1 # and 3 # in Example 11, Example 1, and Example 3.
  • Example 20 is an X-ray diffraction comparison diagram of the core shell materials 12 # , 4 # , 5 # in Example 12, Example 4, and Example 5.
  • Figure 21 is a comparison of X-ray diffraction of core shell materials 13 # , 6 # and 7 # in Example 13, Example 6, and Example 7.
  • Example 22 is a comparison diagram of discharge curves of lithium ion batteries DC11, DC1, DC2, and DC3 prepared by preparing the core-shell materials in Example 11, Example 1, Example 2, and Example 3.
  • Example 23 is a comparison diagram of the ratio performance of lithium ion batteries DC11, DC1, DC2, and DC3 prepared by using the core-shell materials in Example 11, Example 1, Example 2, and Example 3.
  • Example 24 is a comparison diagram of cycle performance of lithium ion batteries DC11, DC1, and DC3 prepared by preparing core-shell materials in Example 11, Example 1, and Example 3.
  • Example 25 is a comparison diagram of discharge curves of lithium ion batteries DC12, DC4, and DC5 prepared by preparing core-shell materials in Example 12, Example 4, and Example 5.
  • Example 26 is a comparison diagram of the rate performance of lithium ion batteries DC12, DC4, and DC5 prepared by preparing the core-shell materials in Example 12, Example 4, and Example 5.
  • Example 27 is a comparison diagram of cycle performance of lithium ion batteries DC12, DC4, and DC5 prepared by preparing core-shell materials in Example 12, Example 4, and Example 5.
  • Example 28 is a comparison diagram of discharge curves of lithium ion batteries DC13, DC6, and DC7 prepared by preparing core-shell materials in Example 13, Example 6, and Example 7.
  • Example 29 is a comparison diagram of the rate performance of lithium ion batteries DC13, DC6, and DC7 prepared by preparing the core-shell materials in Example 13, Example 6, and Example 7.
  • Example 30 is a comparison diagram of cycle performance of lithium ion batteries DC13, DC6, and DC7 prepared by preparing core-shell materials in Example 13, Example 6, and Example 7.
  • Morphological test analysis was performed using a scanning electron microscope S4800H manufactured by Hitachi, Japan, and a transmission electron microscope Tecnai F20 manufactured by FEI, the Netherlands.
  • Elemental zone analysis test analysis was performed using a scanning electron microscope S4800 EDS manufactured by Hitachi, Japan.
  • Electrochemical performance test analysis was carried out using LAND electrochemical test system CT2001A produced by Wuhan Xinnuo Electronics Co., Ltd.
  • Example 1 The shell layer is an amorphous phase core-shell material
  • the mixed solution was prepared according to a molar ratio of Ni, Co, and Mn of 1:1:1, and nickel sulfate hexahydrate, cobalt sulfate heptahydrate, and manganese sulfate monohydrate 87.61 g, 93.72 g, 56.34 g were weighed and dissolved in 500 mL of water. 1000 mL of a 4 mol/L NaOH solution and 1000 mL of a 2 mol/L aqueous ammonia solution were prepared.
  • a nitrogen-protected reaction vessel 200 mL of water was added, and the mixed solution was simultaneously added to the reaction vessel with a 4 mol/L NaOH solution and a 2 mol/L aqueous ammonia solution, and the final pH of the solution was controlled at 11. After the completion of the sedimentation, the precipitate was washed by filtration, and dried at 80 ° C to obtain a precursor P1.
  • the Zr(SO 4 ) 2 solution was added to the dispersion of the precursor P1. After the end of the addition, the pH was adjusted to 8.0 with aqueous ammonia, filtered, washed three times with water, and dried at 100 ° C to obtain a precursor coated with ZrO(OH) 2 . P4.
  • Example 2 Core-shell material in which the shell layer is a crystalline phase
  • the mixed solution was prepared according to a molar ratio of Ni, Co, and Mn of 1:1:1, and nickel sulfate hexahydrate, cobalt sulfate heptahydrate, and manganese sulfate monohydrate 87.61 g, 93.72 g, 56.34 g were weighed and dissolved in 500 mL of water. 1000 mL of a 4 mol/L NaOH solution and 1000 mL of a 2 mol/L aqueous ammonia solution were prepared.
  • a nitrogen-protected reaction vessel 200 mL of water was added, and the mixed solution was simultaneously added to the reaction vessel with a 4 mol/L NaOH solution and a 2 mol/L aqueous ammonia solution, and the final pH of the solution was controlled at 11. After the completion of the sedimentation, the precipitate was washed by filtration, and dried at 80 ° C to obtain a precursor P1.
  • the Co(CH 3 COO) 2 solution was added to the dispersion of the precursor P1. After the end of the addition, the pH was adjusted to 12 with ammonia water, filtered, washed three times with water, and dried at 100 ° C to obtain a precursor of surface coated Co(OH) 2 . Body P5.
  • Example 3 The shell layer is a core-shell material of a crystalline phase and an amorphous phase
  • Example 2 50 g of the precursor P4 in Example 1 was weighed, 200 mL of water was added thereto, and stirred to form a dispersion; 13.03 g of Co(CH 3 COO) 2 ⁇ 4H 2 O was weighed and dissolved in 30 mL of water. A 4 mol/L LiOH solution and a 1 mol/L aqueous ammonia solution were prepared.
  • the Co(CH 3 COO) 2 solution was simultaneously added to the dispersion of the precursor P4 at 4 mol/L of LiOH and an aqueous ammonia solution, and Co(OH) 2 was deposited on the surface of the precursor P4, and the sedimentation pH was controlled at 12.
  • the mixture was filtered and washed with water, and dried at 100 ° C to obtain a composite precursor P6.
  • Example 4 The shell layer is an amorphous phase core-shell material
  • the mixed solution was prepared according to a molar ratio of Ni, Co and Mn of 5:2:3, and respectively, nickel sulfate hexahydrate, cobalt sulfate heptahydrate, manganese sulfate monohydrate 131.42 g, 56.22 g, 50.70 g were weighed and dissolved in 500 mL of water. 1000 mL of a 4 mol/L NaOH solution and 1000 mL of a 2 mol/L aqueous ammonia solution were prepared.
  • a nitrogen-protected reaction vessel 200 mL of water was added, and the mixed solution was simultaneously added to the reaction vessel with a 4 mol/L NaOH solution and a 2 mol/L aqueous ammonia solution, and the final pH of the solution was controlled at 11.5. After the completion of the sedimentation, the precipitate was washed by filtration, and dried at 80 ° C to obtain a precursor P2, as shown in Fig. 2, which was spherical.
  • the Zr(SO 4 ) 2 solution was added to the dispersion of the precursor P2. After the end of the addition, the pH was adjusted to 8.0 with aqueous ammonia, filtered, washed three times with water, and dried at 100 ° C to obtain a precursor coated with ZrO(OH) 2 . P7.
  • Example 5 The shell layer is a core-shell material of a crystalline phase and an amorphous phase
  • Example 4 50 g of the precursor P7 in Example 4 was weighed, 200 mL of water was added, and stirred to form a dispersion; 11.93 g of Co(CH 3 COO) 2 ⁇ 4H 2 O was weighed and dissolved in 50 mL of water. A 4 mol/L LiOH solution and a 1 mol/L aqueous ammonia solution were prepared.
  • the Co(CH 3 COO) 2 solution was simultaneously added to the dispersion of the precursor P7 at 4 mol/L of LiOH and an aqueous ammonia solution, and Co(OH) 2 was deposited on the surface of the precursor P7, and the sedimentation pH was controlled at 12.
  • the mixture was filtered and washed with water, and dried at 100 ° C to obtain a composite precursor P8.
  • the shell-shell material of the embodiment 6 is an amorphous phase
  • the mixed solution was prepared according to a molar ratio of Ni, Co and Mn of 8:1:1, and respectively, nickel nitrate hexahydrate, cobalt nitrate hexahydrate and manganese nitrate 232.63 g, 29.10 g, 25.10 g were weighed and dissolved in 500 mL of water. 1000 Ml of a 5 mol/L NaOH solution and 1000 mL of a 2 mol/L aqueous ammonia solution were prepared.
  • the Zr(SO 4 ) 2 solution was added to the dispersion of the precursor P3. After the end of the addition, the pH was adjusted to 8.0 with ammonia water, filtered, washed three times with water, and dried at 100 ° C to obtain a precursor of surface-coated ZrO(OH) 2 . Body P9.
  • Example 7 The shell layer is a core-shell material of a crystalline phase and an amorphous phase
  • Example 6 50 g of the precursor P9 in Example 6 was weighed, 200 mL of water was added thereto, and stirred to form a dispersion; 14.32 g of Mn(CH 3 COO) 2 ⁇ 4H 2 O was weighed and dissolved in 60 mL of water. A 4 mol/L LiOH solution and a 1 mol/L aqueous ammonia solution were prepared.
  • the Mn(CH 3 COO) 2 solution was simultaneously added to the dispersion of the precursor P9 with 4 mol/L of LiOH and an aqueous ammonia solution, and Mn(OH) 2 was deposited on the surface of the precursor P9, and the sedimentation pH was controlled at 12, and filtered. The mixture was washed with water and dried at 100 ° C to obtain a composite precursor P10.
  • the shell layer of the embodiment 8 is a crystalline phase and an amorphous phase, and has a surface protective layer core-shell material.
  • the sintered core-shell material 2 # 50g in Example 2 was weighed, and 100 mL of water was added to form a suspension. 6.74 g of Mg(NO 3 ) 2 ⁇ 6H 2 O was weighed and dissolved in 50 mL of water to prepare a 1 mol/L NaOH solution.
  • the solution of Mg(NO 3 ) 2 was slowly added to the suspension of 2 # together with the solution of NaOH, and Mg(OH) 2 was allowed to settle on the surface of the positive electrode material, and the pH of the end point was 11.5.
  • the material was calcined at 500 ° C for 6 hours to obtain a surface coated with MgO, the core was LiNi 1/3 Co 1/3 Mn 1/3 O 2 , the shell layer was crystalline phase LiCoO 2 and amorphous phase Li 6 Zr 2 O 7 core-shell material, labeled 8 # .
  • the shell layer of the embodiment 9 is a crystalline phase and an amorphous phase, and has a surface protective layer core-shell material.
  • the sintered core-shell material 4 # 50g in Example 4 was weighed, and 100 mL of water was added to form a suspension. 6.45 g of MgSO 4 ⁇ 7H 2 O was weighed and dissolved in 50 mL of water to prepare a 1 mol/L NaOH solution.
  • the shell layer of the embodiment 10 is a crystalline phase and an amorphous phase, and has a surface protective layer core-shell material.
  • the sintered core-shell material 7 # 50g in Example 7 was weighed, and 100 mL of water was added to form a suspension.
  • the solution of Mg(CH 3 COO) 2 was slowly added to the suspension of the positive electrode material together with the solution of NaOH to precipitate Mg(OH) 2 on the surface of the positive electrode material, and the pH value was 11.5; after filtration and washing, The material was calcined at 500 ° C for 6 hours to obtain a core-shell material coated with MgO, a core of LiNi 0.8 Co 0.1 Mn 0.1 O 2 , a shell of crystalline phase LiMn 2 O 4 and an amorphous phase of Li 6 Zr 2 O 7 . , marked as 10 # .
  • the mixed solution was prepared according to a molar ratio of Ni, Co, and Mn of 1:1:1, and nickel sulfate hexahydrate, cobalt sulfate heptahydrate, and manganese sulfate monohydrate 87.61 g, 93.72 g, 56.34 g were weighed and dissolved in 500 mL of water. 1000 mL of a 4 mol/L NaOH solution and 1000 mL of a 2 mol/L aqueous ammonia solution were prepared.
  • a nitrogen-protected reaction vessel 200 mL of water was added, and the mixed solution was simultaneously added to the reaction vessel with a 4 mol/L NaOH solution and a 2 mol/L aqueous ammonia solution, and the final pH of the solution was controlled at 11. After the completion of the sedimentation, the precipitate was washed by filtration, and dried at 80 ° C to obtain a precursor P1.
  • the mixed solution was prepared according to a molar ratio of Ni, Co and Mn of 5:2:3, and respectively, nickel sulfate hexahydrate, cobalt sulfate heptahydrate, manganese sulfate monohydrate 131.42 g, 56.22 g, 50.70 g were weighed and dissolved in 500 mL of water. 1000 mL of a 4 mol/L NaOH solution and 1000 mL of a 2 mol/L aqueous ammonia solution were prepared.
  • LiOH ⁇ H 2 O 23.94 g was weighed and mixed uniformly with the precursor, sintered at 400 ° C for 6 hours, and then sintered at 850 ° C for 12 hours.
  • a LiNi 0.5 Co 0.2 Mn 0.3 O 2 material was obtained, labeled 12 # .
  • the mixed solution was prepared according to a molar ratio of Ni, Co and Mn of 8:1:1, and respectively, nickel nitrate hexahydrate, cobalt nitrate hexahydrate and manganese nitrate 232.63 g, 29.10 g, 25.10 g were weighed and dissolved in 500 mL of water. 1000 mL of a 5 mol/L NaOH solution and 1000 mL of a 2 mol/L aqueous ammonia solution were prepared.
  • LiNi 0.8 Co 0.1 Mn 0.1 . O 2 material labeled 13 # .
  • the materials 1 # to 13 # obtained in Examples 1 to 13 were used as a positive electrode material, and the conductive agent acetylene black and the binder polyvinylidene fluoride (PVDF) were uniformly mixed in a solvent of nitrogen methylpyrrolidone (NMP), and the positive electrode material,
  • NMP nitrogen methylpyrrolidone
  • the mass ratio of the conductive agent to the binder was 85:10:5, and the uniformly mixed slurry was coated on an aluminum foil, and vacuum-dried at 120 ° C for 12 hours to obtain positive electrodes C1 to C13 of the lithium ion battery.
  • the above-mentioned pole piece is used as a positive electrode, metal lithium is used as a negative electrode, the electrolyte is a solution of 1 mol/L lithium hexafluorophosphate ethylene carbonate and dimethyl carbonate, and the separator is assembled into a CR2032 type by using a 20 ⁇ m thick polyethylene and polypropylene composite material.
  • the precursors P1 to P10 were subjected to morphology test, and the obtained structure is shown in Figs. 1 to 10.
  • the precursor material is spherical and has a diameter of 10 to 40 ⁇ m; the shape of 1 # to 7 #
  • the appearance test, such as the material 2 # , 4 # , 7 # corresponds to Figure 11 ⁇ Figure 13, respectively, from the figure, it can be seen that the material is spherical, and the morphology of other materials is similar.
  • the prepared precursor and the positive electrode material are spherical secondary particles having a particle diameter of about 10 ⁇ m, and the particles are composed of primary particles of 200 to 500 nm.
  • Figures 16, 17 and 18 are projection electron micrographs of the core shell materials prepared in 11 # , 2 # and 3 # respectively. It can be seen from the figure that the surface of the 3 # surface having the composite coating layer prepared in Example 3 is relatively Many tiny crystalline regions and amorphous regions.
  • FIG. 19 is a sample of 13# in Example 13
  • the X-ray diffraction comparison chart of the 6# sample in Example 6 and the 7# sample in Example 7 shows that the synthesized uncoated material is an ⁇ -NaFeO 2 type crystal having a space group of R-3m.
  • the positive electrode material having the composite coating layer (shell layer) is a layered structure in which the space group is R-3m and a structure in which the olivine structure of Pmnb is symbiotic.
  • the element selection analysis is performed on the precursors P1 to P10 and the materials 1 # to 10 # , and the precursors and core-shell materials as in the example 3 are typically as follows.
  • Figure 14 is a diagram showing the element distribution of the cross section of the precursor P6 particles prepared in Example 3. It can be seen from the figure that the concentration of Ni in the precursor from the core to the shell gradually decreases, and the content of Co in the outermost layer appears most. The peak indicates that the content of Co in the shell is higher than that in the core. On the right side of the highest peak of Co concentration, the highest concentration of Zr is present. This result indicates that the synthesized precursor is a core-shell structure in which the core is Ni 0.33 Co 0.33 Mn 0.33 (OH) 2 , the intermediate layer is ZrO(OH) 2 , and the outermost layer is Co(OH) 2 . Fig.
  • Example 15 is a view showing the element distribution of the cross section of the core-shell material 3 # prepared in Example 3, and it can be seen from the figure that the Co element and the Zr element distribution do not show a peak having a higher concentration. Since the oxide precursor decomposes during high-temperature sintering, and reacts to form a uniform mixed region of the crystalline phase LiCoO 2 and the amorphous phase Li 6 Zr 2 O 7 .
  • the coin batteries DC1 to DC13 assembled in the fourteenth embodiment were subjected to a charge and discharge test with a voltage range of 2.8 to 4.3 volts, and the results were as follows.
  • 22 is a discharge curve of DC11, DC1, DC2, and DC3 corresponding to Example 11, Example 1, Example 2, and Example 3, and the discharge voltage was 4.3 V to 2.8 V, and the discharge ratio was 0.1 C. It can be seen from the comparison that the discharge capacity of the modified positive electrode material is similar to that of the unmodified positive electrode material.
  • 23 is a performance test of DC11, DC1, DC2, and DC3 corresponding to Example 11, Example 1, Example 2, and Example 3. The comparison shows that the prepared positive electrode material has improved rate performance and has The positive electrode material rate performance of the composite coating layer (including both the crystal phase and the amorphous phase in the shell layer) is significantly improved.
  • 24 is a cycle performance test curve of DC11, DC1, and DC3 corresponding to Example 11, Example 1, and Example 3. Obviously, the core-shell material coated by the crystalline phase and the amorphous phase improves the circulation of the positive electrode material. performance.
  • 25 is a discharge curve of DC12, DC3, and DC4 corresponding to Example 12, Example 3, and Example 4, and the discharge voltage was 4.3 V to 2.8 V, and the discharge magnification was 0.1 C. It can be seen from the comparison that the discharge capacity of the coated modified positive electrode material is similar to that of the uncoated positive electrode material.
  • 26 is a graph showing the rate performance test of DC12, DC3, and DC4 corresponding to Example 12, Example 3, and Example 4. By comparison, it can be seen that the rate performance of the cathode material having the composite coating layer and the performance of the uncoated sample. Relatively close, it indicates that the composite coating layer (shell layer) in the present application has good lithium ion transport ability.
  • 27 is a cycle performance curve of DC12, DC3, and DC4 corresponding to Example 12, Example 3, and Example 4. The positive electrode material having a composite coating layer (shell layer) has a marked improvement in cycle performance.
  • 28 is a discharge curve of DC13, DC5, and DC6 corresponding to Example 13, Example 5, and Example 6, and the discharge voltage was 4.3 V to 2.8 V, and the discharge magnification was 0.1 C. It can be seen from the comparison that the discharge capacity of the modified positive electrode material is similar to that of the uncoated positive electrode material.
  • 29 is a graph showing the rate performance test of DC13, DC5, and DC6 corresponding to Example 13, Example 5, and Example 6. As can be seen from the comparison, the ratio of the positive electrode material with the composite coating layer (shell layer) is not included. The rate performance of the coated positive electrode material is improved.
  • 30 is a cycle performance curve of DC13, DC5, and DC6 corresponding to Example 13, Example 5, and Example 6.
  • the positive electrode material having a composite coating layer (shell layer) has better cycle performance.

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Abstract

本申请公开了一种核壳材料，所述核壳材料的核物质选自具有式(I)、式(II)所示分子式的化合物中的至少一种；其通过多层前躯体的方法制备得到。所述核壳材料作为正极材料用于锂离子电池领域在发挥高容量优势的同时，具有较好的空气稳定性和安全性能。

Description

一种核壳材料 技术领域
本申请涉及一种核壳材料，属于电极材料领域。
背景技术
传统能源的日益枯竭，使得新型能源的开发、利用得到越来越多的关注。锂离子电池作为绿色新型能源具有能量密度高、循环寿命长、自放电效率小、无记忆效应、安全性好等突出优势，现已广泛应用于电子产品及动力汽车电池等领域。目前，车载锂离子电池面临的挑战一方面是要在保证安全性的前提下提高续航里程，另一方面是要降低成本。正极材料是锂离子电池中决定锂离子电池能量密度的重要组成部分，通过提高正极材料的容量能够有效提高锂离子电池的能量密度。
镍钴锰酸锂和镍钴铝酸锂层状结构正极材料由于具有容量高、倍率性能好、价格低等优点，被认为是目前最有潜力的车载锂电池正极材料。但是，高镍三元材料存在表面活性高、在湿空气中不稳定等问题。
针对高镍三元存在的问题，目前常用的改进方法是在材料表面包覆一层惰性物质，例如MgO、TiO 2、Al 2O 3(Ultrathin Al 2O 3Coatings for Improved Cycling Performance and Thermal Stability of LiNi 0.5Co 0.2Mn 0.3O 2Cathode.Material Electrochimica Acta 203(2016)154-161及专利“一种锂离子电池及其正极材料”、公开号：CN102332577A)、SiO 2(High-performance lithium ion batteries using SiO 2-coated LiNi 0.5Co 0.2Mn 0.3O 2microspheres as cathodes.Journal of Alloys and Compounds 709(2017)708-716)等。包覆的原理是减少三元材料与空气和电解液的直接接触，抑制三元材料表面副反应的生成。其中，大部分包覆方法是针对烧结后的材料进行处理，由于包覆工艺通常需要将烧结好的三元材料置于水或有机溶剂中处理，需要二次煅烧，且在煅烧过程不可避免的会产生局部尖晶石相，引起材料容量降低、循环变差、产气、增加电池安全隐患。此外，目前包覆的方法，包覆量较少，不能形成均匀的包覆层，且包覆层物质没电化学活性，不能具备锂离子脱嵌能力，从而会影响正极材料的电化学性能。
因此本领域尚需提供一种新型的正极材料和制备方法，使获得的正极材料在发挥高容量优势的同时，具有较好的空气稳定性和安全性能。
发明内容
根据本申请的一个方面，提供了一种核壳材料，该材料用于锂离子电池正极材料使正极具有优异的长循环稳定性，同时提高了该材料的安全性和存储稳定性。本发明中提出的具有厚复合包覆层的正极材料，材料制备工艺简单，使用该材料制作电池过程中，具有易于加工的优点；具有良好的应用潜力和巨大的市场空间。
所述核壳材料的核物质选自具有式(I)、式(II)所示分子式的化合物中的至少一种；
Li 1+xNi yCo zMn rM 1-y-z-rO 2            (I)
Li 1+xNi yCo zAl rM 1-y-z-rO 2                (II)
其中，-0.1≤x≤0.2，0＜y≤1，0＜z≤0.5，0≤r≤0.5；
M选自金属中的至少一种。
优选地，M选自Cr、Mg、Ga、Ti、Fe、Cu、Sb、Sr、Ca、K、Na、Sn、Zn中的至少一种。
优选地，所述式(I)和式(II)中，x，y，z，r独立地选自以下范围：-0.1≤x≤0.2，0＜y≤1，0＜z≤0.5，0＜r≤0.5。
优选地，所述式(I)和式(II)中，x，y，z，r独立地选自以下范围：0≤x≤0.1，0＜y≤1，0＜z≤0.5，0＜r≤0.5。
优选地，所述壳层具有电化学活性和锂离子传输能力。
优选地，所述核壳材料的壳层选自晶相材料、非晶相材料中的至少一种；
所述晶相材料选自具有式(III)、式(IV)、式(V)、式(VI)所示化学式的化合物中的至少一种：
Li 1+aNi bCo cMn 1-b-cO 2               (III)
其中，-0.1≤a≤0.2，0≤c≤1，0≤b≤0.5；
Li 1+pMn 2O 4+q                 (IV)
其中，-0.1≤p≤0.2，-0.14≤q≤0.5；
Li 1+uNi 0.5Mn 1.5O 4+v                 (V)
其中，-0.1≤u≤0.2，-0.14≤v≤0.5；
Li 1+tFe 1-sMn sPO 4           (VI)
其中，-0.1≤t≤0.2，0≤s≤1。
优选地，所述非晶相材料选自具有式(VII)、(VIII)所述化学式的化合物中的至少一种：
Li nQ mO z                     (VII)
其中，n+m×Q的价态＝2z；
Q dO f                  (VIII)
其中，d×Q的价态＝2f。
优选地，所述Q选自Nb、Zr、Ta、Y、Sb、Mo、La、Pb、Bi、In、W、Sn、Ga、Cd、Sc、Ba、V、Cr、Ti、Zn中的至少一种。
优选地，所述晶相材料均匀的分散在非晶相材料中。
优选地，所述壳层中的Ni的浓度C Ni 壳小于核中Ni的浓度C Ni 核；
其中，核中某一位置的C Ni 核＝(核中该位置Ni的摩尔数/该位置Ni与其他金属元素的摩尔数之和)×100％；
壳层中某一位置的C Ni 壳＝(壳层中该位置Ni的摩尔数/该位置Ni与其他金属元素的摩尔数之和)×100％。
优选地，所述核壳材料的壳层厚度为1～500nm。
优选地，所述核壳材料的壳层厚度为50～100nm。
优选地，所述核壳材料的壳层厚度为100～300nm。
优选地，所述壳层的层数为1～50层。
进一步优选地，所述壳层的层数为1～30层。
优选地，所述核壳材料的壳层外含有至少一层表面保护层。
优选地，所述表面保护层选自氧化物中的至少一种。
优选地，所述氧化物选自Al 2O 3、MgO、ZrO 2、ZnO、Y 2O 3、Ta 2O 5、Cr 2O 3、Nb 2O 5、Mo 2O 3、V 2O 5、TiO 2、Ga 2O 3、SrO、BaO、WO 2、Sb 2O 5、SnO、CdO、Bi 2O 3、PbO中的至少一种。
本申请的又一方面，提供了制备所述核壳材料的方法，所述方法至少包括多层前驱体法；
其中，多层前驱体的结构为：内部为Ni yCo zMn 1-y-zM 1-y-z-r(OH) 2、Ni yCo zAl 1-y-zM 1-y-z-r(OH) 2中的至少一种，外层依次为Q对应的氧化物、氢氧化物或羟基氧化物，和/或N对应的氧化物、氢氧化物或羟基氧化物；
其中，Q选自Nb、Zr、Ta、Y、Sb、Mo、La、Pb、Bi、In、W、Sn、Ga、Cd、Sc、Ba、V、Cr、Ti、Zn中的至少一种；
其中，N选自Co、Fe、Ni、Mn中的至少一种。
本申请的又一方面，提供了制备所述核壳材料的方法，至少包括以下步骤：
(1)将含有Ni元素、Co元素、Mn元素和/或Al元素、M元素的溶液混合，将体系pH调节值至7～14，经搅拌、洗涤、分离、干燥后，得到前驱体P1；
(2)将步骤(1)中的前驱体P1与含Q元素的溶液混合，将体系pH调节值至2～14，经搅拌、 洗涤、分离、干燥后，得到前驱体P2；
或者将P1与Q的氧化物和/或氢氧化物混合研磨，得到前驱体P2；
(3)重复步骤(2)共计n次，n为大于等于1的正整数，得到前驱体Pn；
(4)将步骤(3)所得前驱体Pn与含N元素的溶液混合，将体系pH调节值至7～14，经搅拌、洗涤、分离、干燥后，得到前驱体P3；
(5)将步骤(4)所得前驱体P3与锂源混合均匀，经烧结后，即得所述核壳材料。
优选地，所述方法还包括以下步骤：
(6)核壳材料与制备表面保护层的原料接触，进行包覆；
当复合包覆层和/或表面保护层的层数≥2时，则按照远离核的方向进行逐层包覆。
优选地，步骤(1)、步骤(2)、步骤(4)中所述将体系pH调节值至7～14，采用碱金属氢氧化物的溶液和/或氨水溶液。
碱金属氢氧化物选自LiOH、NaOH、KOH中的至少一种。
优选地，步骤(1)、步骤(2)、步骤(4)中所述搅拌为搅拌5～24小时；
所述干燥的干燥温度为50～200℃。
优选地，所述干燥的干燥温度为80～200℃。
优选地，所述步骤(1)、步骤(2)、步骤(4)中将体系的pH值调至10～12范围内的某一值。
优选地，所述步骤(5)中锂源选自碳酸锂、氢氧化锂、氯化锂、硝酸锂、醋酸锂中的至少一种。
优选地，所述步骤(5)中的烧结在含氧气氛中进行。
所述含氧气氛选自空气、氧气、氧气与氮气和/或氩气的混合气、空气与氮气和/或氩气的混合气中的至少一种。
优选地，所述步骤(5)中烧结为先在400～700℃烧结2～16小时，再在700～1000℃烧结10～24小时。
优选地，所述步骤(5)中烧结为先在450～600℃烧结4～7小时，再在800～1000℃烧结10～15小时。
优选地，前驱体P1、P2、Pn或P3与锂源的摩尔比为1：0.98～1.2；
其中，前驱体P1、P2、Pn或P3的摩尔数以核中Ni元素、Co元素、M元素、Al元素/Mn元素及壳层前驱体中金属元素的摩尔数之和计；锂源的摩尔数以其中所包含的锂元素的摩尔数计。
所述方法中，步骤(1)～步骤(4)中前驱体的制备方法包括干法混合、湿法球磨、共沉淀中的至少一种。
作为一种优选地具体的实施方式，所述制备核壳材料的方法，至少包括以下步骤：
(i)将Ni、Co、Mn/Al三种盐的溶液按摩尔比混合，配制金属离子总浓度为1.0～3.0mol/L的溶液，同时加入氨水和碱液调节溶液pH值为7～14，沉降结束后，将沉淀过滤、水洗、烘干后得到前驱体P0。
(ii)将Q的氢氧化物沉降或吸附在前驱体P0表面，得到前驱体P1；其中Q盐为：Q为Nb、Zr、Ta、Y、Sb、Mo、La、Pb、Bi、In、W、Sn、Ga、Cd、Sc、Ba、V、Cr、Ti、Zn的可溶性盐(如硫酸盐、硝酸盐、氯化物、醋酸盐)中任意一种或两种以上的组合。
(iii)将N的氢氧化物沉降或吸附在前驱体P1表面，得到前驱体P2；其中N盐为Co、Fe、Ni、Mn的硫酸盐、硝酸盐、氯化物、醋酸盐等可溶性盐中任意一种或两种以上的组合。
(iv)将前驱体P2与锂盐混合均匀，混合均匀的材料在氧气气氛中烧结，得到正极材料。其中，锂盐与前驱体摩尔比0.98-1.20，锂盐为碳酸锂、氢氧化锂、氯化锂、硝酸锂、醋酸锂中的一种或几种。
进一步地，为能使正极材料在高电压继续稳定工作，可以在正极材料的表面增加保护层氧化物。具体地，采用以下步骤：
(v)将步骤(iv)烧结得到的材料放入水中，搅拌后形成分散液，加入C盐的溶液，同时加入碱液， 调节pH值为5-14，在烧结后的材料表面包覆一层C的氢氧化物，得到表面包覆有C的氢氧化物的正极材料。经过滤后进行煅烧，得到表面包覆有C的氧化物的正极材料。
其中，C盐为Al、Mg、Zr、Zn、Y、Ta、Cr、Nb、Mo、V、Ti、Ga、Sr、Ba、W、Sb、Sn、Ga、Cd、Bi、Pb的可溶性盐中任意一种或两种以上的组合，碱液为NaOH、LiOH、KOH中的一种或几种。最终pH值根据选择盐种类的不同控制在不同数值。煅烧温度为300-700℃，煅烧气氛为空气或氧气。采用本发明的上述方法，可以得内部主体为镍钴锰/铝酸锂材料，复合包覆层能在空气中稳定除了在的活性物质，表面的保护层为氧化物，对电极材料起保护作用。
本申请的又一方面，提供了所述核壳材料和/或所述方法制备得到的核壳材料的应用，即：
一种锂离子电池正极材料，所述锂离子电池正极材料含有所述的核壳材料和/或根据所述方法制备得到的核壳材料。
一种锂离子电池，包含所述的锂离子电池正极材料。
所述锂离子电池正极，可用于以有机溶剂或水溶液为电解液的锂离子电池中的正极材料，还可用于采用固态电解质的锂离子电池中的正极材料。
所述锂离子电池的制备方法：将正极材料与导电剂乙炔黑和粘结剂聚偏氟乙烯在氮甲基吡咯烷酮(NMP)溶剂中混合均匀，正极材料、导电剂和粘结剂的质量比为85：10：5，将混合均匀的浆料涂覆在铝箔上，干燥，制得锂离子电池正极。
本发明专利中，提出了一种新的较厚复合包覆层的正极材料和制备方法，通过该方法制备的正极材料，仍然具有较高的放电容量，由于首次采用具有晶相和非晶相的较厚复合包覆层，使正极具有优异的长循环稳定性，同时提高了该材料的安全性和存储稳定性。本发明中提出的具有厚复合包覆层的正极材料，材料制备工艺简单，使用该材料制作电池过程中，具有易于加工的优点。因此，该材料及其制备工艺具有良好的应用潜力和巨大的市场空间。
本申请能产生的有益效果包括：
1)本申请所提供的核壳材料，具有较高的放电容量，采用具有晶相和非晶相的较厚复合包覆层，用于电池正极材料，使正极具有优异的长循环稳定性，同时提高了该材料的安全性和存储稳定性。
2)本申请所提供的核壳材料，所述壳层中具有非晶相和/或晶相组成的复合包覆层，有效抑制内部主体材料部分镍元素的向外扩散，具有低镍表面，应用于电极材料，能够克服现有技术中易被还原从而影响性能的缺陷。
3)本申请所提供的核壳材料，其壳层具有电化学活性和锂离子传输能力，用于电极材料既能阻隔电极材料与电解液直接接触，减少电池内部的副反应，提高安全性能；同时，由于该壳层具有锂离子传输能力，能够有限减缓电池循环过程中的阻抗增加。
4)本申请所提供的核壳材料壳层厚度较普通方法厚，在1-500nm之间；该材料能够在高电压下稳定工作，循环次数较普通材料多，采用该正极材料的锂离子电池具有较长的实用寿命；且在湿空气中稳定性高，材料易于加工。
附图说明
图1为实施例11中制备前驱体P1的形貌图。
图2为实施例12中制备前驱体P2的形貌图。
图3为实施例13中制备前驱体P3的形貌图。
图4为实施例1中制备前驱体P4的形貌图。
图5为实施例2中制备前驱体P5的形貌图。
图6为实施例3中制备前驱体P6的形貌图。
图7为实施例4中制备前驱体P7的形貌图。
图8为实施例5中制备前驱体P8的形貌图。
图9为实施例6中制备前驱体P9的形貌图。
图10为实施例7中制备前驱体P10的形貌图。
图11为实施例2中制备核壳材料2 #的形貌图。
图12为实施例4中制备核壳材料4 #的形貌图。
图13为实施例7中制备核壳材料7 #的形貌图。
图14为实施例3中制备的前驱体P6颗粒横截面元素分布图。
图15为实施例3中制备的核壳材料3 #颗粒横截面元素分布图。
图16为实施例11中制备核壳材料11 #的透射电镜图。
图17为实施例2中制备核壳材料2 #的透射电镜图。
图18为实施例3中制备核壳材料3 #的透射电镜图。
图19为实施例11、实施例1、实施例3中制备核壳材料11 #、1 #、3 #的X射线衍射对比图。
图20为实施例12、实施例4、实施例5中制备核壳材料12 #、4 #、5 #的X射线衍射对比图。
图21为实施例13、实施例6、实施例7中制备核壳材料13 #、6 #、7 #的X射线衍射对比图。
图22为实施例11、实施例1、实施例2和实施例3中核壳材料制备得到的锂离子电池DC11、DC1、DC2、DC3的放电曲线对比图。
图23为实施例11、实施例1、实施例2和实施例3中核壳材料制备得到的锂离子电池DC11、DC1、DC2、DC3的倍率性能对比图
图24为实施例11、实施例1、实施例3中核壳材料制备得到的锂离子电池DC11、DC1、DC3的循环性能对比图。
图25为实施例12、实施例4、实施例5中核壳材料制备得到的锂离子电池DC12、DC4、DC5的放电曲线对比图。
图26为实施例12、实施例4、实施例5中核壳材料制备得到的锂离子电池DC12、DC4、DC5的倍率性能对比图。
图27为实施例12、实施例4、实施例5中核壳材料制备得到的锂离子电池DC12、DC4、DC5的循环性能对比图。
图28为实施例13、实施例6、实施例7中核壳材料制备得到的锂离子电池DC13、DC6、DC7的放电曲线对比图。
图29为实施例13、实施例6、实施例7中核壳材料制备得到的锂离子电池DC13、DC6、DC7的倍率性能对比图。
图30为实施例13、实施例6、实施例7中核壳材料制备得到的锂离子电池DC13、DC6、DC7的循环性能对比图。
具体实施方式
下面结合实施例详述本申请，但本申请并不局限于这些实施例。
如无特别说明，本申请的实施例中的原料均通过商业途径购买。
本申请的实施例中分析方法如下：
利用日本Hitachi生产的扫描电子显微镜S4800H和荷兰FEI生产的透射电子显微镜Tecnai F20进行形貌测试分析。
利用德国Bruker AXS生产的X射线粉末衍射仪D8 Advance进行结构测试分析。
利用日本Hitachi生产的扫描电子显微镜S4800 EDS进行元素选区分析测试分析。
利用武汉鑫诺电子有限公司生产的LAND电化学测试***CT2001A进行电化学性能测试分析。
实施例1壳层为非晶相的核壳材料
按照Ni、Co、Mn的摩尔比为1：1：1配制混合溶液，分别称量六水硫酸镍、七水硫酸钴、一水硫酸锰87.61g，93.72g，56.34g，加入500mL水溶解。配制1000mL 4mol/L NaOH溶液和1000mL2mol/L的氨水溶液。
在氮气保护的反应釜中，加入200mL水，将混合溶液与4mol/L的NaOH溶液和2mol/L的氨水溶液同时加入到反应釜中，溶液最终pH值控制在11。沉降结束后，将沉淀过滤洗涤，80℃烘干后得到前驱体P1。
称量前驱体P1 50g，加200mL水，搅拌形成分散液。配制1mol/L氨水溶液。称量11.42g Zr(SO 4) 2·4H 2O，加30mL水溶解。
将Zr(SO 4) 2溶液加入到前驱体P1的分散液中，加入结束后，用氨水调节pH至8.0，过滤，水洗三次，100℃干燥后得到表面包覆ZrO(OH) 2的前驱体P4。
称量上述P4前驱体10g，锂盐与前驱体按照摩尔比为1.2：1的比例混合，称量LiOH·H 2O 5.34g与前驱体P4混合均匀，在600℃烧结6小时后，在900℃烧结12小时，得到核为LiNi 1/3Co 1/3Mn 1/3O 2，壳层为Li 6Zr 2O 7的核壳材料，标记为1 #。
实施例2壳层为晶相的核壳材料
按照Ni、Co、Mn的摩尔比为1：1：1配制混合溶液，分别称量六水硫酸镍、七水硫酸钴、一水硫酸锰87.61g，93.72g，56.34g，加入500mL水溶解。配制1000mL 4mol/L NaOH溶液和1000mL2mol/L的氨水溶液。
在氮气保护的反应釜中，加入200mL水，将混合溶液与4mol/L的NaOH溶液和2mol/L的氨水溶液同时加入到反应釜中，溶液最终pH值控制在11。沉降结束后，将沉淀过滤洗涤，80℃烘干后得到前驱体P1。
称量前驱体P1 50g，加200mL水，搅拌形成分散液。配制1mol/L氨水溶液。称量14.67g Co(CH 3COO) 2·4H 2O，加60mL水溶解。
将Co(CH 3COO) 2溶液加入到前驱体P1的分散液中，加入结束后，用氨水调节pH至12，过滤，水洗三次，100℃干燥后得到表面包覆Co(OH) 2的前驱体P5。
称量上述P5前驱体10g，锂盐与前驱体按照摩尔比1.2的比例混合，称量LiOH·H 2O 5.45g与前驱体P5混合均匀，在600℃烧结6小时后，在900℃烧结12小时，得到核为LiNi 1/3Co 1/3Mn 1/3O 2，壳层为LiCoO 2的核壳材料，标记为2 #。
实施例3壳层为晶相和非晶相的核壳材料
称量实施例1中的前驱体P4 50g，加200mL水，搅拌形成分散液；称量13.03g Co(CH 3COO) 2·4H 2O，溶解于30mL水中。配制4mol/L的LiOH溶液和1mol/L氨水溶液。
将Co(CH 3COO) 2溶液与4mol/L的LiOH和氨水溶液同时加入到前驱体P4的分散液中，将Co(OH) 2沉降在前驱体P4表面，沉降pH值控制在12。过滤水洗，100℃干燥后得到复合前驱体P6。
称量上述P6前驱体50g，锂盐与前驱体按照摩尔比1.1：1的比例混合，称量LiOH·H 2O 24.52g，与前驱体P6混合均匀，在500℃烧结6小时后，在950℃烧结12小时，得到核为LiNi 1/3Co 1/3Mn 1/3O 2，壳层为晶相LiCoO 2和非晶相Li 6Zr 2O 7的核壳材料，标记为3 #。
实施例4壳层为非晶相的核壳材料
按照Ni、Co、Mn的摩尔比为5：2：3配制混合溶液，分别称量六水硫酸镍、七水硫酸钴、一水硫酸锰131.42g，56.22g，50.70g，加入500mL水溶解。配制1000mL 4mol/L NaOH溶液，和1000mL 2mol/L的氨水溶液。
在氮气保护的反应釜中，加入200mL水，将混合溶液与4mol/L的NaOH溶液和2mol/L的氨水溶液同时加入到反应釜中，溶液最终pH控制在11.5。沉降结束后，将沉淀过滤洗涤，80℃烘干后得到前驱体P2，见图2，为球形。
称量前驱体P2 50g，加200mL水，搅拌形成分散液。配制1mol/L氨水溶液。称量11.36g Zr(SO 4) 2·4H 2O，加30mL水溶解。
将Zr(SO 4) 2溶液加入到前驱体P2的分散液中，加入结束后，用氨水调节pH至8.0，过滤，水洗三次，100℃干燥后得到表面包覆ZrO(OH) 2的前驱体P7。
称量上述P7前驱体10g，锂盐与前驱体按照摩尔比1.2：1的比例混合，称量LiOH·H 2O 5.31g与前驱体P7混合均匀，在600℃烧结6小时后，在900℃烧结12小时，得到核为LiNi 0.5Co 0.2Mn 0.3O 2，壳层为Li 6Zr 2O 7的核壳材料，标记为4 #。
实施例5壳层为晶相和非晶相的核壳材料
称量实施例4中的前驱体P7 50g，加200mL水，搅拌形成分散液；称量11.93g Co(CH 3COO) 2·4H 2O，溶解于50mL水中。配制4mol/L的LiOH溶液和1mol/L氨水溶液。
将Co(CH 3COO) 2溶液与4mol/L的LiOH和氨水溶液同时加入到前驱体P7的分散液中，将Co(OH) 2沉降在前驱体P7表面，沉降pH值控制在12。过滤水洗，100℃干燥后得到复合前驱体P8。
称量上述P8前驱体50g，锂盐与前驱体按照摩尔比1.1：1的比例混合，称量LiOH·H 2O 24.40g，与前驱体P8混合均匀，在500℃烧结6小时后，在950℃烧结12小时，得到核为LiNi 0.5Co 0.2Mn 0.3O 2，壳层为晶相LiCoO 2和非晶相Li 6Zr 2O 7的核壳材料，标记为5 #。
实施例6壳层为非晶相的核壳材料
按照Ni、Co、Mn的摩尔比为8：1：1配制混合溶液，分别称量六水硝酸镍、六水硝酸钴、四水硝酸锰232.63g，29.10g，25.10g，加入500mL水溶解。配制1000Ml 5mol/L NaOH溶液，和1000mL 2mol/L的氨水溶液。
在氩气保护的反应釜中，加入200mL水，将混合溶液与5mol/L的NaOH溶液和2mol/L的氨水溶液同时加入到反应釜中，溶液最终pH值控制在11.5。沉降结束后，将沉淀过滤洗涤，80℃烘干后得到前驱体P3。
称量前驱体P3 50g，加200mL水，搅拌形成分散液。配制1mol/L氨水溶液。称量11.32g Zr(SO 4) 2·4H 2O，加60mL水溶解。
将Zr(SO 4) 2溶液加入到前驱体P3的分散液中，加入结束后，用氨水调节pH值至8.0，过滤，水洗三次，100℃干燥后得到表面包覆ZrO(OH) 2的前驱体P9。
称量上述P9前驱体10g，锂盐与前驱体按照摩尔比1.2：1的比例混合，称量LiOH·H 2O 5.30g与前驱体P9混合均匀，在600℃烧结6小时后，在900℃烧结12小时，得到核为LiNi 0.8Co 0.1Mn 0.1O 2，壳层为Li 6Zr 2O 7的核壳材料，标记为6 #。
实施例7壳层为晶相和非晶相的核壳材料
称量实施例6中前驱体P9 50g，加200mL水，搅拌形成分散液；称量14.32g Mn(CH 3COO) 2·4H 2O，溶解于60mL水中。配制4mol/L的LiOH溶液和1mol/L氨水溶液。
将Mn(CH 3COO) 2溶液与4mol/L的LiOH和氨水溶液同时加入到前驱体P9的分散液中，将Mn(OH) 2沉降在前驱体P9表面，沉降pH值控制在12，过滤水洗，100℃干燥后得到复合前驱体P10。
称量上述P10前驱体50g，锂盐与前驱体按照摩尔比1.2：1的比例混合，称量LiOH·H 2O 26.65g，与前驱体P10混合均匀，在480℃烧结6小时后，在950℃烧结12小时，得到核为LiNi 0.8Co 0.1Mn 0.1O 2，壳层为晶相LiMn 2O 4和非晶相Li 6Zr 2O 7的核壳材料，标记为7 #。
实施例8壳层为晶相和非晶相、具有表面保护层核壳材料
称量实施例2中烧结后的核壳材料2 #50g，加100mL水形成悬浊液。称量Mg(NO 3) 2·6H 2O 6.74g，溶解于50mL水中，配制1mol/L的NaOH溶液。
将Mg(NO 3) 2的溶液与NaOH的溶液一起，缓慢加入到2 #的悬浊液中，使Mg(OH) 2沉降在正极材料表面，终点pH值为11.5。过滤、水洗后，将材料在500℃煅烧6小时，得到表面包覆有MgO，核为LiNi 1/3Co 1/3Mn 1/3O 2，壳层为晶相LiCoO 2和非晶相Li 6Zr 2O 7的核壳材料，标记为8 #。
实施例9壳层为晶相和非晶相、具有表面保护层核壳材料
称量实施例4中烧结后的核壳材料4 #50g，加100mL水形成悬浊液。称量MgSO 4·7H 2O 6.45g，溶解于50mL水中，配制1mol/L的NaOH溶液。
将MgSO 4的溶液与NaOH的溶液一起，缓慢加入到4 #的悬浊液中，使Mg(OH) 2沉降在正极材料表面，终点pH值为11.5；过滤、水洗后，将材料在500℃煅烧6小时，得到表面包覆有MgO，核为LiNi 0.5Co 0.2Mn 0.3O 2，壳层为晶相LiCoO 2和非晶相Li 6Zr 2O 7的核壳材料，标记为9 #。
实施例10壳层为晶相和非晶相、具有表面保护层核壳材料
称量实施例7中烧结后的核壳材料7 #50g，加100mL水形成悬浊液。称量Mg(CH 3COO) 2·4H 2O5.59g，溶解于50mL水中，配制1mol/L的NaOH溶液。
将Mg(CH 3COO) 2的溶液与NaOH的溶液一起，缓慢加入到正极材料的悬浊液中，使Mg(OH) 2沉降在正极材料表面，终点pH值为11.5；过滤、水洗后，将材料在500℃煅烧6小时，得到表面包覆有MgO，核为LiNi 0.8Co 0.1Mn 0.1O 2，壳层为晶相LiMn 2O 4和非晶相Li 6Zr 2O 7的核壳材料，标记为10 #。
实施例11未包覆的材料
按照Ni、Co、Mn的摩尔比为1：1：1配制混合溶液，分别称量六水硫酸镍、七水硫酸钴、一水硫酸锰87.61g，93.72g，56.34g，加入500mL水溶解。配制1000mL 4mol/L NaOH溶液，和1000mL 2mol/L的氨水溶液。
在氮气保护的反应釜中，加入200mL水，将混合溶液与4mol/L的NaOH溶液和2mol/L的氨水溶液同时加入到反应釜中，溶液最终pH值控制在11。沉降结束后，将沉淀过滤洗涤，80℃烘干后得到前驱体P1。
称量上述P1前驱体50g，按照锂盐与前驱体摩尔比1.05：1混合，称量LiOH·H 2O 24.07g与前驱体混合均匀，在400℃烧结6小时后，在850℃烧结12小时，得到LiNi 1/3Co 1/3Mn 1/3O 2材料，标记为11 #。
实施例12未包覆的材料
按照Ni、Co、Mn的摩尔比为5：2：3配制混合溶液，分别称量六水硫酸镍、七水硫酸钴、一水硫酸锰131.42g，56.22g，50.70g，加入500mL水溶解。配制1000mL 4mol/L NaOH溶液，和1000mL 2mol/L的氨水溶液。
在氮气保护的反应釜中，加入200mL水，将混合溶液与4mol/L的NaOH溶液和2mol/L的氨水溶液同时加入到反应釜中，溶液最终pH值控制在11.5。沉降结束后，将沉淀过滤洗涤，80℃烘干后得到前驱体P2。
称量上述P2前驱体50g，按照锂盐与前驱体摩尔比1.05：1混合，称量LiOH·H 2O 23.94g与前驱体混合均匀，在400℃烧结6小时后，在850℃烧结12小时，得到LiNi 0.5Co 0.2Mn 0.3O 2材料，标记为12 #。
实施例13未包覆的材料
按照Ni、Co、Mn的摩尔比为8：1：1配制混合溶液，分别称量六水硝酸镍、六水硝酸钴、四水硝酸锰232.63g，29.10g，25.10g，加入500mL水溶解。配制1000mL5mol/L NaOH溶液，和1000mL 2mol/L的氨水溶液。
在氩气保护的反应釜中，加入200mL水，将混合溶液与5mol/L的NaOH溶液和2mol/L的氨水溶液同时加入到反应釜中，溶液最终pH值控制在11.5。沉降结束后，将沉淀过滤洗涤，80℃烘干后得到前驱体P3，。
称量上述P3前驱体100g，按照锂盐与前驱体摩尔比1.05：1混合，称量LiOH·H 2O 47.71g与前驱体混合均匀，在850℃烧结12小时，得到LiNi 0.8Co 0.1Mn 0.1O 2材料，标记为13 #。
实施例14制备锂离子电池
将实施例1～13中得到的材料1 #～13 #作为正极材料与导电剂乙炔黑和粘结剂聚偏氟乙烯(PVDF)在氮甲基吡咯烷酮(NMP)溶剂中混合均匀，正极材料、导电剂和粘结剂的质量比为85：10：5，将混合均匀的浆料涂覆在铝箔上，120℃下真空干燥12小时，制得锂离子电池正极C1～C13。
使用上述极片为正极，以金属锂为负极，电解液采用1mol/L六氟磷酸锂的碳酸乙烯酯和碳酸二甲酯的溶液，隔膜采用20微米厚的聚乙烯和聚丙烯复合材料，组装成CR2032型纽扣锂离子电池DC1～DC13。
实施例15材料的形貌测试
将前驱体P1～P10进行形貌测试，得到的结构如图1～图10所示，从图中可以看出，前驱体材料为球形，直径为10～40μm；对1 #～7 #进行形貌测试，典型的如材料2 #，4 #，7 #，分别对应图11～图13，从图中，可以看到，材料呈现球形，其他材料的形貌与之类似。由图1～图13可以清楚地看到制备的前驱体及正极材料均为粒径约为10微米的球形二次颗粒，该颗粒由200～500nm的一次颗粒组成。
对上述实施例制备得到的样品1 #～13 #，进行透射电镜分析，典型的分析结果如下所述：
图16、17和18分别为11 #、2 #、3 #中制备核壳材料的投射电镜图，从图中可以看出，实施例3中制备的具有复合包覆层的3 #表面存在较多微小的结晶区和无定型区。
实施例16材料的结构测试
对上述实施例制备得到的样品1 #～13 #，进行X射线衍射分析，典型的分析结果如下所述：
图19和图20分别为实施例11中11 #样品、实施例1中1 #样品和实施例3中3 #样品、实施例12中12 #样品、实施例4中4 #样品和实施例5中5 #样品的X射线衍射对比图，XRD的测试结果显示合成的核壳材料是空间群为R-3m的α-NaFeO 2型晶格结构；图21为实施例13中的13#样品、实施例6中的6#样品和实施例7中的7#样的X射线衍射对比图，XRD的测试结果显示合成的未包覆的材料是空间群为R-3m的α-NaFeO 2型晶格结构，具有复合包覆层(壳层)的正极材料为空间群为R-3m的层状结构和Pmnb的橄榄石结构共生的结构。
实施例17元素选区分析
对前驱体P1～P10以及材料1 #～10 #进行元素选取分析，典型的如实施例3中的前驱体和核壳材料，具体如下。
图14为实施例3中制备的前驱体P6颗粒横截面的元素分布图，由图可以看出制备的前驱体从核芯到壳层Ni元素浓度逐渐降低，Co元素含量在最外层出现最高峰，说明壳层Co元素含量较核芯内部高，在Co元素浓度最高峰右侧，出现Zr元素浓度最高峰。该结果说明合成的前驱体是核芯为Ni 0.33Co 0.33Mn 0.33(OH) 2、中间层为ZrO(OH) 2、最外层为Co(OH) 2的壳核壳结构。图15为实施例3中制备的核壳材料3 #的颗粒横截面的元素分布图，从图中可以看出Co元素和Zr元素分布并未出现浓度较高的峰。由于在高温烧结过程中，氧化物前驱体分解，并反应形成晶相LiCoO 2和非晶相Li 6Zr 2O 7的均匀混合区。
实施例18材料的电化学性能测试
将实施例14中组装成的纽扣电池DC1～DC13进行充放电测试，电压范围为2.8-4.3伏特，结果如下。
图22为实施例11、实施例1、实施例2和实施例3对应的DC11、DC1、DC2、DC3的放电曲线，放电电压为4.3V～2.8V、放电倍率为0.1C。通过对比可以看出，改性正极材料放电容量与未改性正极材料相近。图23为实施例11、实施例1、实施例2和实施例3对应的DC11、DC1、DC2、DC3的倍率性能测试，通过对比可以看出制备的改性正极材料倍率性能得到提升，且具有复合包覆层(壳层中既包含晶相又包含非晶相)的正极材料倍率性能提高较显著。图24为实施例11、实施例1和实施例3对应的DC11、DC1、DC3的循环性能测试曲线，明显的，由晶相和非晶相进行包覆的核壳材料提高了正极材料的循环性能。
图25为实施例12、实施例3、实施例4对应的DC12、DC3、DC4的放电曲线，放电电压为4.3V～2.8V、放电倍率为0.1C。通过对比可以看出，包覆改性正极材料放电容量与未包覆正极材料相近。图26为实施例12、实施例3、实施例4对应的DC12、DC3、DC4的倍率性能测试曲线，通过对比可以看出，具有复合包覆层的正极材料的倍率性能与未包覆样品性能比较接近，说明本申请中的复合包覆层(壳层)具有良好的锂离子传输能力。图27为实施例12、实施例3、实施例4对应的DC12、DC3、DC4的循环性能曲线，具有复合包覆层(壳层)的正极材料其循环性能明显提高。
图28为实施例13、实施例5、实施例6对应的DC13、DC5、DC6的放电曲线，放电电压为4.3V～2.8V、放电倍率为0.1C。通过对比可以看出，改性正极材料放电容量与未包覆正极材料相近。图29为实施例13、实施例5、实施例6对应的DC13、DC5、DC6的倍率性能测试曲线，通过对比可以看出，具有复合包覆层(壳层)的正极材料倍率性能较未包覆的正极材料的倍率性能有所提高。图30为实施例13、实施例5、实施例6对应的DC13、DC5、DC6的循环性能曲线，具有复合包覆层(壳层)的正极材料其循环性能较好。
以上所述，仅是本申请的几个实施例，并非对本申请做任何形式的限制，虽然本申请以较佳实施例揭示如上，然而并非用以限制本申请，任何熟悉本专业的技术人员，在不脱离本申请技术方案的范围内，利用上述揭示的技术内容做出些许的变动或修饰均等同于等效实施案例，均属于技术方案范围内。

Claims (15)

  1. 一种核壳材料，其特征在于，所述核壳材料的核物质选自具有式(I)、式(II)所示分子式的化合物中的至少一种；
    Li 1+xNi yCo zMn rM 1-y-z-rO 2  (I)
    Li 1+xNi yCo zAl rM 1-y-z-rO 2  (II)其中，-0.1≤x≤0.2，0＜y≤1，0＜z≤0.5，0＜r≤0.5；
    M选自金属中的至少一种。
  2. 根据权利要求1所述的核壳材料，其特征在于，所述M选自Cr、Mg、Ga、Ti、Fe、Cu、Sb、Sr、Ca、K、Na、Sn、Zn中的至少一种。
  3. 根据权利要求1所述的核壳材料，其特征在于，所述核壳材料的壳层选自晶相材料、非晶相材料中的至少一种；
    所述晶相材料选自具有式(III)、式(IV)、式(V)、式(VI)所示化学式的化合物中的至少一种：
    Li 1+aNi bCo cMn 1-b-cO 2   (III)
    其中，-0.1≤a≤0.2，0≤c≤1，0≤b≤0.5；
    Li 1+pMn 2O 4+q  (IV)
    其中，-0.1≤p≤0.2，-0.14≤q≤0.5；
    Li 1+uNi 0.5Mn 1.5O 4+v  (V)
    其中，-0.1≤u≤0.2，-0.14≤v≤0.5；
    Li 1+tFe 1-sMn sPO 4  (VI)
    其中，-0.1≤t≤0.2，0≤s≤1。
  4. 根据权利要求3所述的核壳材料，其特征在于，所述非晶相材料选自具有式(VII)、(VIII)所述化学式的化合物中的至少一种：
    Li nQ mO z  (VII)
    其中，n+m×Q的价态＝2z；
    Q dO f  (VIII)
    其中，d×Q的价态＝2f。
  5. 根据权利要求4所述的核壳材料，其特征在于，所述Q选自Nb、Zr、Ta、Y、Sb、Mo、La、Pb、Bi、In、W、Sn、Ga、Cd、Sc、Ba、V、Cr、Ti、Zn中的至少一种；
  6. 根据权利要求3所述的核壳材料，其特征在于，所述晶相材料均匀的分散在非晶相材料中。
  7. 根据权利要求1至6任一项所述的核壳材料，其特征在于，所述壳层中的Ni的浓度C Ni 壳小于核中Ni的浓度C Ni 核；
    其中，核中某一位置的C Ni 核＝(核中该位置Ni的摩尔数/该位置Ni与其他金属元素的摩尔数之和)×100％；
    壳层中某一位置的C Ni 壳＝(壳层中该位置Ni的摩尔数/该位置Ni与其他金属元素的摩尔数之和)×100％。
  8. 根据权利要求1所述的核壳材料，其特征在于，所述核壳材料的壳层厚度为1～500nm。
  9. 根据权利要求1所述的核壳材料，其特征在于，所述核壳材料的壳层的层数为1～50层。
  10. 根据权利要求9所述的核壳材料，其特征在于，所述核壳材料的壳层的层数为1～30层。
  11. 根据权利要求1至10任一项所述的核壳材料，其特征在于，所述核壳材料的壳层外含有至少一层表面保护层。
  12. 根据权利要求11所述的核壳材料，其特征在于，所述表面保护层选自氧化物中的至少一种。
  13. 根据权利要求12所述的核壳材料，其特征在于，所述氧化物选自Al 2O 3、MgO、ZrO 2、ZnO、Y 2O 3、Ta 2O 5、Cr 2O 3、Nb 2O 5、Mo 2O 3、V 2O 5、TiO 2、Ga 2O 3、SrO、BaO、WO 2、Sb 2O 5、SnO、CdO、Bi 2O 3、PbO中的至少一种。
  14. 一种锂离子电池正极材料，其特征在于，所述锂离子电池正极材料含有权利要求1至13任一项所述的核壳材料。
  15. 一种锂离子电池，其特征在于，包含权利要求14所述的锂离子电池正极材料。
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