WO2023165160A1 - Positive electrode material, and preparation method therefor and use thereof - Google Patents

Positive electrode material, and preparation method therefor and use thereof Download PDF

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WO2023165160A1
WO2023165160A1 PCT/CN2022/131114 CN2022131114W WO2023165160A1 WO 2023165160 A1 WO2023165160 A1 WO 2023165160A1 CN 2022131114 W CN2022131114 W CN 2022131114W WO 2023165160 A1 WO2023165160 A1 WO 2023165160A1
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lithium
positive electrode
sintering
electrode material
containing compound
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PCT/CN2022/131114
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French (fr)
Chinese (zh)
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刘婧婧
李长东
阮丁山
蔡勇
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广东邦普循环科技有限公司
湖南邦普循环科技有限公司
湖南邦普汽车循环有限公司
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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
    • 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
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • 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 invention belongs to the technical field of lithium ion batteries, and in particular relates to a positive electrode material and a preparation method and application thereof.
  • NCM Nickel cobalt lithium manganese oxide
  • ternary cathode material LiNi x Co y Mn 1-xy O 2 , 0 ⁇ x, y ⁇ 1
  • the first strategy will not only reduce the structural stability of the material, especially the structure is easily damaged under high voltage and reduce the cycle performance of the material; in addition, the high-nickel ternary material needs to be washed with water or tri-calcined due to the relatively high residual alkali on the surface. process to reduce the residual alkali on the surface and improve the surface stability of the material, which will increase the processing cost of high-nickel ternary materials.
  • the second strategy is to directly increase the working voltage of the material.
  • the upper limit voltage of the layered ternary material LiNi x Co y Mn 1-xy O 2 increases, the higher the degree of Li+ migration, the greater the structural phase change caused, and the cycle process Accompanied by the generation of new inactive phases, the electrical properties of the material will deteriorate rapidly; in addition, the Co content will be reduced, and the traditional high-temperature solid-state reaction method will obtain a low-cobalt NCM material with high surface energy. Materials with high surface energy will not only reduce The cycle stability of the material under high voltage will also reduce the compacted density of the material, thereby reducing the energy density of the material.
  • a positive electrode material is provided.
  • the positive electrode material is a high-voltage low-cobalt positive electrode material with low surface energy crystal plane preferred orientation, mainly composed of LiNi x Mn y Co z (Co a M b )O 2 core with low surface energy crystal plane preferred orientation and high voltage Stable Li( Co c N d )O 2 coating composition, this specific structure makes it exhibit higher Compacted density and high voltage cycle stability.
  • the technical solution adopted in the present invention is:
  • a positive electrode material comprising an inner layer and an outer layer
  • the inner layer comprises LiNixMnyCoz ( CoaMb ) O2 ;
  • the outer layer contains Li(Co c N d )O 2 , and the molar ratio of the Li element in the outer layer to the inner layer is A;
  • the Co a M b is at least one of an oxide mixed sol containing Co and M, and an oxyhydroxide sol;
  • x+y+z+a+b 1, 0 ⁇ A ⁇ 0.03, 0.65 ⁇ c ⁇ 0.95, 0.35 ⁇ d ⁇ 0.05;
  • M includes at least one of Mg, Al, Ti, Zr, Sr, Y, Ce, W, La, Sn, Mo, Fe, B or Si;
  • N includes at least one of Al, Ti, W, B or Mg.
  • the cathode material exhibits excellent compacted density and high voltage cycle stability.
  • the technical solution adopted in the present invention is:
  • a method for preparing positive electrode materials comprising the steps of:
  • S2 mixes the product obtained in S1 with the Co-containing compound, the N-containing compound, and the remaining lithium source, and then sinters to obtain the positive electrode material;
  • the precursor includes Ni x+a+b Co y Mnz (OH) 2 ;
  • the N-containing compound includes at least one of oxides, hydrated oxides, oxyhydroxides, and lithium metal oxide compounds containing Al, Ti, W, B, and Mg.
  • the precursor is a hexagonal layered structure.
  • the positive electrode material LiNi x Mn y Co z (Co a M b )O 2 ⁇ ALi(Co c N d )O 2 has a hexagonal layered structure, the space group is (R-3m), the hexagonal layered structure is stable, and can Provide good high temperature resistance and friction resistance to the material.
  • the LiNi x Mny Co z (Co a M b )O 2 is obtained by melting Co a M b into the pores on the surface of the precursor and finally sintering.
  • the Co a M b is a low surface energy substance, and the precursor is a high surface energy substance;
  • the Co a M b is in the form of a sol, and the Co a M b is adhered to the precursor with high surface energy. Under low-temperature sintering, the Co a M b melts into the pores of the precursor crystal to form a composite crystal, and the subsequent During the sintering process, the low surface energy Co a M b inhibits the growth of high surface energy crystals and exposes more low surface energy crystal planes, resulting in the product LiNi x Mn y Co z (Co a M b ) O2 has a lower surface energy.
  • the preferred orientation of low surface crystal planes can also reduce the degree of side reactions of the material, Improve material stability.
  • Li(Co c N d )O 2 is used to coat LiNi x Mny Co z (Co a M b )O 2 . Due to the high voltage stability of Li(Co c N d )O 2 , the positive electrode material LiNi x Mny Co z (Co a M b )O 2 ⁇ ALi(Co c N d )O 2 is more efficient than conventional low-cobalt LiNi x Co y Mnz O 2 (0 ⁇ Co ⁇ 0.15) exhibited higher compacted density and high voltage cycle stability.
  • LiNi x Mn y Co z (Co a M b )O 2 ⁇ ALi(Co c N d )O 2 has low surface energy crystal plane preferred orientation, I(003)/I(012) ⁇ 8, I(003)/ I(110) ⁇ 7.
  • the lithium source includes at least one of lithium carbonate, lithium nitrate, lithium hydroxide, lithium oxide, lithium oxalate, and lithium acetate. Further preferably, the lithium source is at least one of lithium carbonate and lithium hydroxide.
  • the Co-containing compound includes at least one of Co-containing hydroxides, oxyhydroxides, and carbonates.
  • step S2 after the LiNixMnyCoz ( CoaMb ) O2 is broken into a single crystal or a single crystal-like morphology , it is then mixed with the Co-containing compound, The N-containing compound and the remaining lithium source are mixed.
  • a high-voltage positive electrode material LiNi x Mn y Co z (Co a M b ) O 2 ⁇ ALi (Co c N d ) O 2 with high compacted density is obtained.
  • the mass ratio of the above-mentioned Co a M b to the precursor is 8-20:10.
  • the method for coating Co a M b on the surface of the precursor includes a liquid phase coating method.
  • the specific steps of the liquid-phase coating method are: adding the precursor to the mixed sol with high-speed stirring, centrifuging after continuous stirring for 1-15 minutes, and then drying in an oven at 105-150°C for 2-8 hours, and further preferably The stirring speed is 200-1000rpm/min, and the sol/material mass ratio is 0.6-2.0.
  • the sintering in step S1 is first sintering at 250-550° C., followed by temperature-raising sintering.
  • the temperature of the elevated temperature sintering described in S1 above is 750-1050°C, and the sintering at this temperature can inhibit the growth of high surface energy crystal planes of the material, and make more low surface energy The crystal planes of the product are exposed, resulting in a lower surface energy of the product LiNi x Mny Co z (Co a M b )O 2 .
  • the time for heating and sintering described in the above S1 is 8-30h.
  • the sintering in the above S2 is sintering at 450°C-850°C for 3h-10h. Further preferably, the sintering in the above S2 is carried out in an atmosphere with an oxygen concentration of 20-100%, at 550° C. to 750° C. for 4 h to 8 h.
  • the above-mentioned method for preparing positive electrode material is carried out in the environment of air, oxygen and air and oxygen mixed in any proportion.
  • Another aspect of the present invention also relates to the application of the above positive electrode material in batteries.
  • the LiNi x Mny Co z (Co a M b ) O 2 is obtained by melting Co a M b into the pores on the surface of the precursor and finally sintering.
  • the Co a M b is a low surface energy substance
  • the precursor is a high surface energy substance
  • the Co a M b is in the form of a sol
  • the Co a M b is adhered to a high surface energy precursor
  • Under low temperature sintering Co a M b melts into the pores of the precursor crystal to form a composite crystal
  • the low surface energy Co a M b inhibits the growth of high surface energy crystals and makes more The crystal faces with low surface energy are exposed, resulting in lower surface energy of the product LiNi x Mny Co z (Co a M b )O 2 .
  • the preferred orientation of low surface crystal planes can also reduce the degree of side reactions of the material, Improve material stability.
  • Li(Co c N d )O 2 is used to coat LiNi x Mny Co z (Co a M b )O 2 . Due to the high voltage stability of Li(Co c N d )O 2 , the positive electrode material LiNi x Mny Co z (Co a M b )O 2 ⁇ ALi(Co c N d )O 2 is more efficient than conventional low-cobalt LiNi x Co y Mnz O 2 (0 ⁇ Co ⁇ 0.15) exhibited higher compacted density and high voltage cycle stability.
  • the preparation method of the positive electrode material is simple and easy, the requirements for equipment are simple, the process is highly controllable, and the cost is low, which can be used in industrial production.
  • Fig. 1 is the XRD figure of the described cathode material of embodiment 1;
  • FIG. 2 is a scanning electron microscope (SEM) image of the cathode material of Example 2.
  • SEM scanning electron microscope
  • Lumpy LiNi 0.563 Co 0.068 Mn 0.34 ⁇ (Co 0.012 Y 0.008 )O 2 was mechanically crushed into a D50 of 3.8 ⁇ m, with single-crystal and single-crystal particle morphology, and then mixed with 195.8g CoOOH, 80g TiO 2 and 131.4g LiOH ⁇ H 2 O is mechanically mixed and sintered at 650° C. for 5 hours to obtain the positive electrode material with low surface energy crystal plane preferred orientation:
  • Lumpy LiNi 0.716 Co 0.038 Mn 0.20 (Co 0.032 Al 0.008 )O 2 is mechanically crushed into a D50 of 4.8 ⁇ m, which has a single crystal morphology, and then mixed with 101.89g Co(OH) 2 , 18.78g TiO 2 , 18.33g Al(OH) 3 , 70.53g LiOH ⁇ H 2 O were mixed mechanically and then sintered at 550°C for 5 hours to obtain the positive electrode material with preferred orientation of crystal planes with low surface energy:
  • Lumpy LiNi 0.608 Co 0.048 Mn 0.31 (Co 0.08 B 0.011 Zr 0.014 )O 2 is mechanically crushed into a D50 of 5.0 microns with a single crystal morphology, and then mixed with 88.98g CoOOH, 5.0g WO 3 , 2.0g Al 2 O 3. 25.8g LiOH ⁇ H 2 O and 6.45g Li 2 O were mechanically mixed and then sintered at 750°C for 8 hours to obtain the positive electrode material with preferred orientation of crystal planes with low surface energy:
  • 523NCM nickel-cobalt-manganese ternary material
  • 712NCM, and 613NCM bought in the market are used as positive electrode materials
  • PVDF polyvinylidene fluoride
  • activated carbon is used as a conductive agent.
  • the mass percentage is 96:2:2, NMP (N-methylpyrrolidone) is used as the solvent, stirred into a slurry, and the slurry is evenly coated on the aluminum foil with a coating machine, and the positive electrode sheet is made after drying, and the electrolyte is 1.02mol/L lithium hexafluorophosphate, DMC (dimethyl carbonate)/EMC (ethyl methyl carbonate)/PC (polycarbonate) as the electrolyte solvent, and graphite as the negative electrode to make a pouch battery.
  • NMP N-methylpyrrolidone
  • DMC dimethyl carbonate
  • EMC ethyl methyl carbonate
  • PC polycarbonate
  • the above-mentioned battery is formed by a lithium-ion battery, and after aging, the discharge capacity of the battery, the rate performance, cycle performance and storage capacity under different current conditions are tested.
  • Discharge capacity first charge at 0.33C to 4.5V, constant voltage to 0.05C, discharge to 2.8V at a rate of 0.1C at 20°C, and the initial discharge voltage is 4.5V;
  • Rate performance at room temperature, charge at 0.33C constant current to 4.5V, then charge at constant voltage to 0.05C; then discharge at 0.33C and 4C constant current to 2.8V, record the discharge at 0.33C and 4C capacity.
  • High-temperature storage performance fully charge the cell to 4.5V, then place it in an oven at 60°C and bake for 30 days, record the volume change of the cell before and after baking, and record the volume change rate.
  • the data of compaction density of pole piece in Table 1 is: (mass of pole piece after rolling - mass of uncoated pole piece) / area of pole piece / (thickness of pole piece after rolling - thickness of uncoated pole piece) ;
  • the data of high-temperature storage performance is: (volume of battery cell after baking - volume of battery cell before baking) / volume of battery cell before baking ⁇ 100%;
  • the data of the rate performance is: (4C rate discharge capacity/0.33C rate discharge capacity) ⁇ 100%.
  • the discharge capacity, 4.5V cycle performance, 4.5V high-temperature storage and pole piece compaction density of Example 1 are significantly improved compared with the comparison sample 523NCM, and the rate performance is basically the same;
  • the compacted density of the pole piece of the single crystal or similar single crystal battery is basically 3.4g/cm 3 , but the present invention can increase it to 3.5g/cm 3 .
  • the current cycle voltage of commercial batteries is 4.2-4.4V, but the present invention can maintain good cycle performance at 4.5V.
  • Example 2 Compared with the comparative sample 721NCM, the discharge capacity, high temperature cycle performance, high temperature storage, pole piece compaction density and rate performance of Example 2 are significantly improved; the discharge capacity, high temperature cycle performance, high temperature storage, rate performance and extreme pressure of Example 3 Compared with the comparison sample 613NCM, the solid density has been significantly improved.
  • the positive electrode material with low surface preferred orientation provided in the present invention can effectively inhibit the deterioration of electrochemical performance caused by the structure change of the material in the high-voltage cycle process, and at the same time improve the compaction density of the material, so that the comprehensive Improved performance.

Abstract

The present invention discloses a positive electrode material, and a preparation method therefor and the use thereof. The positive electrode material comprises an inner layer and an outer layer, wherein the inner layer comprises LiNixMnyCoz(CoaMb)O2; the outer layer comprises Li(CocNd)O2; the molar ratio of Li in the outer layer to Li in the inner layer is A; the CoaMb is at least one of an oxide mixed sol containing Co and M, and a hydroxyl oxidized sol; 0.35 ≤ x ≤ 0.75, 0.2 ≤ y ≤ 0.50, 0.01 < z < 0.13, 0 < a ≤ 0.05, and 0 < b ≤ 0.05; x + y + z + a + b = 1, 0 < A ≤ 0.03, 0.65 < c ≤ 0.95, and 0.35 < d ≤ 0.05; M comprises at least one of Mg, Al, Ti, Zr, Sr, Y, Ce, W, La, Sn, Mo, Fe, B or Si; and N comprises at least one of Al, Ti, W, B or Mg. The positive electrode material LiNixMnyCoz(CoaMb)O2·ALi(CocNd)O2 exhibits a higher compaction density and high-voltage cycling stability than the conventional low-cobalt material LiNixCoyMnzO2 (0 < Co ≤ 0.15).

Description

一种正极材料及其制备方法与应用A kind of positive electrode material and its preparation method and application 技术领域technical field
本发明属于锂离子电池技术领域，具体涉及一种正极材料及其制备方法与应用。The invention belongs to the technical field of lithium ion batteries, and in particular relates to a positive electrode material and a preparation method and application thereof.
背景技术Background technique
在国家倡导绿色低碳发展理念的背景下，动力锂电池产业迅猛发展。正极材料作为锂离子电池核心部分之一，占据锂电池成本的40％以上。镍钴锰酸锂(NCM)三元正极材料(LiNi xCo yMn 1-x-yO 2，0＜x，y＜1)具有能量密度高、安全性能好、成本低廉等优点，是现在动力锂电池正极材料的主要类型之一。 Under the background of the country advocating the concept of green and low-carbon development, the power lithium battery industry has developed rapidly. As one of the core parts of lithium-ion batteries, cathode materials account for more than 40% of the cost of lithium-ion batteries. Nickel cobalt lithium manganese oxide (NCM) ternary cathode material (LiNi x Co y Mn 1-xy O 2 , 0<x, y<1) has the advantages of high energy density, good safety performance, and low cost. It is the current power lithium One of the main types of battery cathode materials.
近年来，为了节约成本以及提高锂离子电池的能量密度。常用策略有二：一、提高镍含量来达到提高能量密度；二、降低钴含量，并提高材料的工作电压。In recent years, in order to save costs and improve the energy density of lithium-ion batteries. There are two commonly used strategies: 1. Increase the nickel content to increase the energy density; 2. Reduce the cobalt content and increase the working voltage of the material.
其中，策略一，不仅会降低材料的结构稳定性，特别是高电压下结构容易被破坏而降低材料的循环性能；另外，高镍三元材料由于表面残余碱比较高，需要采用水洗或三烧工艺来降低表面残余碱、提高材料的表面稳定性，这样会提高高镍三元材料的加工成本。Among them, the first strategy will not only reduce the structural stability of the material, especially the structure is easily damaged under high voltage and reduce the cycle performance of the material; in addition, the high-nickel ternary material needs to be washed with water or tri-calcined due to the relatively high residual alkali on the surface. process to reduce the residual alkali on the surface and improve the surface stability of the material, which will increase the processing cost of high-nickel ternary materials.
策略二，直接提高材料工作电压，层状三元材料LiNi xCo yMn 1-x-yO 2随着上限电压升高，Li+迁出的程度越高，引起的结构相变越大，并且循环过程伴随着新的非活性相生成，最终导致材料的电性能迅速恶化；另外降低Co含量，采用传统的高温固相反应法会获得高表面能的低钴NCM材料，高表面能的材料不仅会降低材料的高电压下的循环稳定性，还会降低材料的压实密度，进而降低材料的能量密度。 The second strategy is to directly increase the working voltage of the material. As the upper limit voltage of the layered ternary material LiNi x Co y Mn 1-xy O 2 increases, the higher the degree of Li+ migration, the greater the structural phase change caused, and the cycle process Accompanied by the generation of new inactive phases, the electrical properties of the material will deteriorate rapidly; in addition, the Co content will be reduced, and the traditional high-temperature solid-state reaction method will obtain a low-cobalt NCM material with high surface energy. Materials with high surface energy will not only reduce The cycle stability of the material under high voltage will also reduce the compacted density of the material, thereby reducing the energy density of the material.
发明内容Contents of the invention
本发明所要解决的第一个技术问题是：The first technical problem to be solved by the present invention is:
提供一种正极材料。Provided is a positive electrode material.
所述正极材料为具有低表面能晶面择优取向的高电压低钴正极材料，主要由具有低表面能晶择优取向的LiNi xMn yCo z(Co aM b)O 2内核和具有高电压稳定性的Li(Co cN d)O 2包覆层组成，该特定的结构使得其比常规的低钴正极材料LiNi xCo yMn zO 2(0<Co≤0.15)表现出更高的压实密度和高电压循环稳定性。 The positive electrode material is a high-voltage low-cobalt positive electrode material with low surface energy crystal plane preferred orientation, mainly composed of LiNi x Mn y Co z (Co a M b )O 2 core with low surface energy crystal plane preferred orientation and high voltage Stable Li( Co c N d )O 2 coating composition, this specific structure makes it exhibit higher Compacted density and high voltage cycle stability.
本发明所要解决的第二个技术问题是：The second technical problem to be solved by the present invention is:
提供一种制备正极材料的方法。Provided is a method for preparing positive electrode materials.
本发明所要解决的第三个技术问题是：The third technical problem to be solved by the present invention is:
上述正极材料的应用。Application of the above-mentioned positive electrode material.
为了解决上述第一个技术问题，本发明采用的技术方案为：In order to solve the above-mentioned first technical problem, the technical solution adopted in the present invention is:
一种正极材料，所述正极材料包括内层和外层；A positive electrode material comprising an inner layer and an outer layer;
所述内层包含LiNi xMn yCo z(Co aM b)O 2； The inner layer comprises LiNixMnyCoz ( CoaMb ) O2 ;
所述外层包含Li(Co cN d)O 2，所述外层与内层中Li元素的摩尔比为A； The outer layer contains Li(Co c N d )O 2 , and the molar ratio of the Li element in the outer layer to the inner layer is A;
所述Co aM b为含Co和M的氧化物混合溶胶、羟基氧化溶胶中的至少一种； The Co a M b is at least one of an oxide mixed sol containing Co and M, and an oxyhydroxide sol;
其中，0.35≤x≤0.75，0.2≤y≤0.50，0.01<z<0.13，0<a≤0.05，0<b≤0.05；Among them, 0.35≤x≤0.75, 0.2≤y≤0.50, 0.01<z<0.13, 0<a≤0.05, 0<b≤0.05;
x+y+z+a+b＝1，0<A≤0.03，0.65<c≤0.95，0.35<d≤0.05；x+y+z+a+b=1, 0<A≤0.03, 0.65<c≤0.95, 0.35<d≤0.05;
M包括Mg、Al、Ti、Zr、Sr、Y、Ce、W、La、Sn、Mo、Fe、B或Si中的至少一种；M includes at least one of Mg, Al, Ti, Zr, Sr, Y, Ce, W, La, Sn, Mo, Fe, B or Si;
N包括Al、Ti、W、B或Mg中的至少一种。N includes at least one of Al, Ti, W, B or Mg.
所述正极材料表现出优良的压实密度和高电压循环稳定性。The cathode material exhibits excellent compacted density and high voltage cycle stability.
为了解决上述第二个技术问题，本发明采用的技术方案为：In order to solve the above-mentioned second technical problem, the technical solution adopted in the present invention is:
一种制备正极材料的方法，包括以下步骤：A method for preparing positive electrode materials, comprising the steps of:
S1将所述Co aM b涂覆于前驱体表面，与部分锂源混合，烧结得到LiNi xMn yCo z(Co aM b)O 2； S1 Coating the Co a M b on the surface of the precursor, mixing with part of the lithium source, and sintering to obtain LiNi x Mny Co z (Co a M b )O 2 ;
S2将S1得到的产物与含Co化合物、含N化合物、余量锂源混合后烧结，得到所述正极材料；S2 mixes the product obtained in S1 with the Co-containing compound, the N-containing compound, and the remaining lithium source, and then sinters to obtain the positive electrode material;
所述前驱体包括Ni x+a+bCo yMn z(OH) 2； The precursor includes Ni x+a+b Co y Mnz (OH) 2 ;
含N化合物包括含Al、Ti、W、B、Mg的氧化物、水合氧化物、羟基氧化物、金属酸锂化合物中的至少一种。The N-containing compound includes at least one of oxides, hydrated oxides, oxyhydroxides, and lithium metal oxide compounds containing Al, Ti, W, B, and Mg.
所述前驱体是六方层状结构。The precursor is a hexagonal layered structure.
所述正极材料LiNi xMn yCo z(Co aM b)O 2·ALi(Co cN d)O 2是六方层状结构，空间群为(R-3m)，六方层状结构稳定，能给材料提供良好的耐高温性和耐摩擦性。 The positive electrode material LiNi x Mn y Co z (Co a M b )O 2 ·ALi(Co c N d )O 2 has a hexagonal layered structure, the space group is (R-3m), the hexagonal layered structure is stable, and can Provide good high temperature resistance and friction resistance to the material.
所述LiNi xMn yCo z(Co aM b)O 2是由Co aM b熔融入前驱体表面的孔隙中并最终烧结得到的。 The LiNi x Mny Co z (Co a M b )O 2 is obtained by melting Co a M b into the pores on the surface of the precursor and finally sintering.
其中，所述Co aM b为低表面能物质、所述前驱体为高表面能物质； Wherein, the Co a M b is a low surface energy substance, and the precursor is a high surface energy substance;
所述Co aM b为溶胶状，将Co aM b粘附在高表面能的前驱体上，在低温烧结下，Co aM b熔融入前驱体晶体的孔隙中形成复合的晶体，随后的升温烧结过程中，低表面能的Co aM b抑制高表面能的晶体长大，并使更多的低表面能的晶面暴露出来，致使产物LiNi xMn yCo z(Co aM b)O 2的表面能较低。从而避免了高表面能带来的高摩擦阻力和恶化物料堆积紧密度的影响，以达到提高最终产品正极材料压实密度的目标，同时低表面晶面择优取向也能降低材料的副反应 程度，提高材料的稳定性。 The Co a M b is in the form of a sol, and the Co a M b is adhered to the precursor with high surface energy. Under low-temperature sintering, the Co a M b melts into the pores of the precursor crystal to form a composite crystal, and the subsequent During the sintering process, the low surface energy Co a M b inhibits the growth of high surface energy crystals and exposes more low surface energy crystal planes, resulting in the product LiNi x Mn y Co z (Co a M b ) O2 has a lower surface energy. Thereby avoiding the influence of high frictional resistance brought by high surface energy and deterioration of material packing density, so as to achieve the goal of increasing the compaction density of the final positive electrode material, and at the same time, the preferred orientation of low surface crystal planes can also reduce the degree of side reactions of the material, Improve material stability.
之后，在LiNi xMn yCo z(Co aM b)O 2的基础上，再以Li(Co cN d)O 2层包覆LiNi xMn yCo z(Co aM b)O 2，由于Li(Co cN d)O 2具有高电压稳定性，因而所述正极材料LiNi xMn yCo z(Co aM b)O 2·ALi(Co cN d)O 2比常规的低钴LiNi xCo yMn zO 2(0<Co≤0.15)表现出更高的压实密度和高电压循环稳定性。 Afterwards, on the basis of LiNi x Mny Co z (Co a M b )O 2 , Li(Co c N d )O 2 is used to coat LiNi x Mny Co z (Co a M b )O 2 , Due to the high voltage stability of Li(Co c N d )O 2 , the positive electrode material LiNi x Mny Co z (Co a M b )O 2 ·ALi(Co c N d )O 2 is more efficient than conventional low-cobalt LiNi x Co y Mnz O 2 (0<Co≤0.15) exhibited higher compacted density and high voltage cycle stability.
LiNi xMn yCo z(Co aM b)O 2·ALi(Co cN d)O 2具有低表面能晶面择优取向，I(003)/I(012)≥8，I(003)/I(110)≥7。 LiNi x Mn y Co z (Co a M b )O 2 ·ALi(Co c N d )O 2 has low surface energy crystal plane preferred orientation, I(003)/I(012)≥8, I(003)/ I(110)≥7.
根据本发明的一种实施方式，上述锂源包括碳酸锂、硝酸锂、氢氧化锂、氧化锂、草酸锂、乙酸锂中的至少一种。进一步优选的，锂源为碳酸锂、氢氧化锂中的至少一种。According to an embodiment of the present invention, the lithium source includes at least one of lithium carbonate, lithium nitrate, lithium hydroxide, lithium oxide, lithium oxalate, and lithium acetate. Further preferably, the lithium source is at least one of lithium carbonate and lithium hydroxide.
根据本发明的一种实施方式，上述含Co化合物包括含Co氢氧化物、羟基氧化物、碳酸化物中的至少一种。According to an embodiment of the present invention, the Co-containing compound includes at least one of Co-containing hydroxides, oxyhydroxides, and carbonates.
根据本发明的一种实施方式，上述步骤S2中，所述LiNi xMn yCo z(Co aM b)O 2破碎成单晶或类单晶形貌后，再与所述含Co化合物、所述含N化合物、所述余量锂源混合。通过将块状结晶产物破碎，再重新烧结，从而得到高压实密度的高电压正极材料LiNi xMn yCo z(Co aM b)O 2·ALi(Co cN d)O 2。 According to one embodiment of the present invention, in the above step S2 , after the LiNixMnyCoz ( CoaMb ) O2 is broken into a single crystal or a single crystal-like morphology , it is then mixed with the Co-containing compound, The N-containing compound and the remaining lithium source are mixed. By crushing the massive crystalline product and re-sintering, a high-voltage positive electrode material LiNi x Mn y Co z (Co a M b ) O 2 ·ALi (Co c N d ) O 2 with high compacted density is obtained.
根据本发明的一种实施方式，上述Co aM b与所述前驱体的质量比为8-20：10。 According to an embodiment of the present invention, the mass ratio of the above-mentioned Co a M b to the precursor is 8-20:10.
根据本发明的一种实施方式，上述将Co aM b包覆于前驱体表面的方法包括液相包覆法。进一步优选的，液相包覆法具体步骤为，将前驱体加入到高速搅拌的混合溶胶中，持续搅拌1-15min后离心，再在105-150℃烘箱中烘2-8h，再进一步优选的搅拌速度为200-1000rpm/min，溶胶/料质量比0.6-2.0。 According to an embodiment of the present invention, the method for coating Co a M b on the surface of the precursor includes a liquid phase coating method. Further preferably, the specific steps of the liquid-phase coating method are: adding the precursor to the mixed sol with high-speed stirring, centrifuging after continuous stirring for 1-15 minutes, and then drying in an oven at 105-150°C for 2-8 hours, and further preferably The stirring speed is 200-1000rpm/min, and the sol/material mass ratio is 0.6-2.0.
根据本发明的一种实施方式，步骤S1所述烧结为先在250-550℃下烧结，随后再进行升温烧结。According to one embodiment of the present invention, the sintering in step S1 is first sintering at 250-550° C., followed by temperature-raising sintering.
根据本发明的一种实施方式，上述S1中所述升温烧结的温度为750-1050℃，在该温度下的烧结，能够抑制材料的高表面能晶面生长，并使更多的低表面能的晶面暴露出来，致使产物LiNi xMn yCo z(Co aM b)O 2的表面能较低。 According to an embodiment of the present invention, the temperature of the elevated temperature sintering described in S1 above is 750-1050°C, and the sintering at this temperature can inhibit the growth of high surface energy crystal planes of the material, and make more low surface energy The crystal planes of the product are exposed, resulting in a lower surface energy of the product LiNi x Mny Co z (Co a M b )O 2 .
上述S1中所述升温烧结的时间为8-30h。The time for heating and sintering described in the above S1 is 8-30h.
根据本发明的一种实施方式，上述S2中所述烧结为在450℃～850℃下烧结3h-10h。进一步优选的，上述S2中所述烧结在氧气浓度为20-100％的气氛中，550℃～750℃下烧结4h～8h。According to an embodiment of the present invention, the sintering in the above S2 is sintering at 450°C-850°C for 3h-10h. Further preferably, the sintering in the above S2 is carried out in an atmosphere with an oxygen concentration of 20-100%, at 550° C. to 750° C. for 4 h to 8 h.
根据本发明的一种实施方式，上述制备正极材料的方法是在空气、氧气以及任何比例混 合的空气和氧气的环境中进行的。According to one embodiment of the present invention, the above-mentioned method for preparing positive electrode material is carried out in the environment of air, oxygen and air and oxygen mixed in any proportion.
本发明的另一个方面，还涉及上述正极材料在电池中的应用。Another aspect of the present invention also relates to the application of the above positive electrode material in batteries.
上述技术方案中的一个技术方案至少具有如下优点或有益效果之一：One of the above technical solutions has at least one of the following advantages or beneficial effects:
1.所述LiNi xMn yCo z(Co aM b)O 2是由Co aM b熔融入前驱体表面的孔隙中并最终烧结得到的。其中，所述Co aM b为低表面能物质、所述前驱体为高表面能物质；所述Co aM b为溶胶状，将Co aM b粘附在高表面能的前驱体上，在低温烧结下，Co aM b熔融入前驱体晶体的孔隙中形成复合的晶体，随后的升温烧结过程中，低表面能的Co aM b抑制高表面能的晶体长大，并使更多的低表面能的晶面暴露出来，致使产物LiNi xMn yCo z(Co aM b)O 2的表面能较低。从而避免了高表面能带来的高摩擦阻力和恶化物料堆积紧密度的影响，以达到提高最终产品正极材料压实密度的目标，同时低表面晶面择优取向也能降低材料的副反应程度，提高材料的稳定性。 1. The LiNi x Mny Co z (Co a M b ) O 2 is obtained by melting Co a M b into the pores on the surface of the precursor and finally sintering. Wherein, the Co a M b is a low surface energy substance, and the precursor is a high surface energy substance; the Co a M b is in the form of a sol, and the Co a M b is adhered to a high surface energy precursor, Under low temperature sintering, Co a M b melts into the pores of the precursor crystal to form a composite crystal, and during the subsequent sintering process, the low surface energy Co a M b inhibits the growth of high surface energy crystals and makes more The crystal faces with low surface energy are exposed, resulting in lower surface energy of the product LiNi x Mny Co z (Co a M b )O 2 . Thereby avoiding the influence of high frictional resistance brought by high surface energy and deterioration of material packing density, so as to achieve the goal of increasing the compaction density of the final positive electrode material, and at the same time, the preferred orientation of low surface crystal planes can also reduce the degree of side reactions of the material, Improve material stability.
之后，在LiNi xMn yCo z(Co aM b)O 2的基础上，再以Li(Co cN d)O 2层包覆LiNi xMn yCo z(Co aM b)O 2，由于Li(Co cN d)O 2具有高电压稳定性，因而所述正极材料LiNi xMn yCo z(Co aM b)O 2·ALi(Co cN d)O 2比常规的低钴LiNi xCo yMn zO 2(0<Co≤0.15)表现出更高的压实密度和高电压循环稳定性。 Afterwards, on the basis of LiNi x Mny Co z (Co a M b )O 2 , Li(Co c N d )O 2 is used to coat LiNi x Mny Co z (Co a M b )O 2 , Due to the high voltage stability of Li(Co c N d )O 2 , the positive electrode material LiNi x Mny Co z (Co a M b )O 2 ·ALi(Co c N d )O 2 is more efficient than conventional low-cobalt LiNi x Co y Mnz O 2 (0<Co≤0.15) exhibited higher compacted density and high voltage cycle stability.
2.所述正极材料的制备方法简单易行，对设备要求简单，工艺可控性强、成本低，可用于工业化生产。2. The preparation method of the positive electrode material is simple and easy, the requirements for equipment are simple, the process is highly controllable, and the cost is low, which can be used in industrial production.
附图说明Description of drawings
构成本发明的一部分的说明书附图用来提供对本发明的进一步理解，本发明的示意性实施例及其说明用于解释本发明，并不构成对本发明的不当限定。The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention.
图1为实施例1的所述正极材料的XRD图；Fig. 1 is the XRD figure of the described cathode material of embodiment 1;
图2为实施例2的所述正极材料扫描电子显微镜(SEM)图。FIG. 2 is a scanning electron microscope (SEM) image of the cathode material of Example 2. FIG.
具体实施方式Detailed ways
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明的范围。The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of the present invention.
实施例1Example 1
1)将8kg Co 0.6Y 0.4OOH溶胶(浓度为2.5wt％)加入高速搅拌机中，在高速搅拌(速度为600rpm/min)条件下，再将10kg的Ni 0.58Co 0.07Mn 0.35(OH) 2加入到搅拌机中持续搅拌2min，然后转移到离心机离心，再将离心后的前驱体，在120℃条件下烘干4小时，获得低表面能 前体Ni 0.58Co 0.07Mn 0.35(OH) 2·0.02(Co 0.6Y 0.4OOH)。 1) Put 8kg of Co 0.6 Y 0.4 OOH sol (concentration: 2.5wt%) into the high-speed mixer, and then add 10kg of Ni 0.58 Co 0.07 Mn 0.35 (OH) 2 under high-speed stirring (speed: 600rpm/min) Stir in a mixer for 2 minutes, then transfer to a centrifuge for centrifugation, and then dry the centrifuged precursor at 120°C for 4 hours to obtain a low surface energy precursor Ni 0.58 Co 0.07 Mn 0.35 (OH) 2 ·0.02 (Co 0.6 Y 0.4 OOH).
2)将10kg前体Ni 0.58Co 0.07Mn 0.35(OH) 2·0.02(Co 0.6Y 0.4OOH)与4.35kg Li 2CO 3机械混合后，放到气氛炉中，250℃烧结2h，然后升温至950℃烧结10h，得到块状LiNi 0.563Co 0.068Mn 0.34.(Co 0.012Y 0.008)O 2； 2) Mechanically mix 10kg of the precursor Ni 0.58 Co 0.07 Mn 0.35 (OH) 2 ·0.02(Co 0.6 Y 0.4 OOH) with 4.35kg Li 2 CO 3 , put it in an atmosphere furnace, sinter at 250°C for 2h, and then raise the temperature to Sintering at 950°C for 10 hours to obtain bulk LiNi 0.563 Co 0.068 Mn 0.34 .(Co 0.012 Y 0.008 )O 2 ;
3)块状LiNi 0.563Co 0.068Mn 0.34·(Co 0.012Y 0.008)O 2机械破碎成D50为3.8μm，具有类单晶和单晶颗粒形貌，再与195.8g CoOOH、80g TiO 2和131.4g LiOH·H 2O进行机械混合后进行在650℃下烧结5小时，得到具有低表面能晶面择优取向的所述正极材料： 3) Lumpy LiNi 0.563 Co 0.068 Mn 0.34 ·(Co 0.012 Y 0.008 )O 2 was mechanically crushed into a D50 of 3.8 μm, with single-crystal and single-crystal particle morphology, and then mixed with 195.8g CoOOH, 80g TiO 2 and 131.4g LiOH·H 2 O is mechanically mixed and sintered at 650° C. for 5 hours to obtain the positive electrode material with low surface energy crystal plane preferred orientation:
LiNi 0.563Co 0.068Mn 0.34·(Co 0.012Y 0.008)O 2·0.03Li(Co 0.65Ti 0.35)O 2。 LiNi 0.563 Co 0.068 Mn 0.34 ·(Co 0.012 Y 0.008 )O 2 ·0.03Li(Co 0.65 Ti 0.35 )O 2 .
其XRD如图1所述，图1显示其I(003)/I(012)为10.1，I(003)/I(110)为8.1。Its XRD is as described in Figure 1, and Figure 1 shows that its I(003)/I(012) is 10.1, and I(003)/I(110) is 8.1.
实施例2Example 2
1)将20kg Co 0.8Al 0.2OOH溶胶(浓度为1.6wt％)加入高速搅拌机中，在高速搅拌(速度为800rpm/min)条件下，再将10kg的Ni 0.75Co 0.04Mn 0.21(OH) 2加入搅拌机中持续搅拌2min，然后转移到离心机离心，再将离心后的前驱体，在150℃条件下烘干2小时，获得低表面能前体： 1) Add 20kg of Co 0.8 Al 0.2 OOH sol (concentration: 1.6wt%) into the high-speed mixer, and then add 10kg of Ni 0.75 Co 0.04 Mn 0.21 (OH) 2 under high-speed stirring (speed: 800rpm/min) Continue to stir in the mixer for 2 minutes, then transfer to a centrifuge for centrifugation, and then dry the centrifuged precursor at 150°C for 2 hours to obtain a low surface energy precursor:
Ni 0.75Co 0.04Mn 0.21(OH) 2·0.04(Co 0.8Al 0.2OOH)。 Ni 0.75 Co 0.04 Mn 0.21 (OH) 2 ·0.04(Co 0.8 Al 0.2 OOH).
2)将10kg前体Ni 0.75Co 0.04Mn 0.21(OH) 2·0.04(Co 0.8Al 0.2OOH)与4.80kg LiOH·H 2O机械混合后，放到气氛炉中，350℃烧结2h，然后升温至920℃烧结11h，得到块状LiNi 0.716Co 0.038Mn 0.20(Co 0.032Al 0.008)O 2。 2) Mechanically mix 10kg of the precursor Ni 0.75 Co 0.04 Mn 0.21 (OH) 2 ·0.04(Co 0.8 Al 0.2 OOH) with 4.80kg LiOH·H 2 O, put it in an atmosphere furnace, sinter at 350°C for 2h, and then raise the temperature Sinter at 920°C for 11 hours to obtain bulk LiNi 0.716 Co 0.038 Mn 0.20 (Co 0.032 Al 0.008 )O 2 .
3)块状LiNi 0.716Co 0.038Mn 0.20(Co 0.032Al 0.008)O 2机械破碎成D50为4.8μm，具有类单晶形貌，再与101.89g Co(OH) 2、18.78g TiO 2、18.33g Al(OH) 3、70.53g LiOH·H 2O进行机械混合后进行在550℃下烧结5小时，得到具有低表面能晶面择优取向的所述正极材料： 3) Lumpy LiNi 0.716 Co 0.038 Mn 0.20 (Co 0.032 Al 0.008 )O 2 is mechanically crushed into a D50 of 4.8 μm, which has a single crystal morphology, and then mixed with 101.89g Co(OH) 2 , 18.78g TiO 2 , 18.33g Al(OH) 3 , 70.53g LiOH·H 2 O were mixed mechanically and then sintered at 550°C for 5 hours to obtain the positive electrode material with preferred orientation of crystal planes with low surface energy:
LiNi 0.716Co 0.038Mn 0.20(Co 0.032Al 0.008)O 2·0.015Li(Co 0.7Ti 0.15Al 0.15)O 2。 LiNi 0.716 Co 0.038 Mn 0.20 (Co 0.032 Al 0.008 )O 2 ·0.015Li(Co 0.7 Ti 0.15 Al 0.15 )O 2 .
其XRD显示其I(003)/I(012)为9.8，I(003)/I(110)为8.3。Its XRD shows that its I(003)/I(012) is 9.8, and I(003)/I(110) is 8.3.
其SEM图见图2，所述正极材料的颗粒约为2μm。Its SEM image is shown in FIG. 2 , and the particles of the positive electrode material are about 2 μm.
实施例3Example 3
1)将12kg(CoOOH) 0.3·(B 2O 3) 0.2·(ZrO 2) 0.5溶胶(浓度为3wt％)加入高速搅拌机中，在高速搅拌(速度为400rpm/min)条件下，再将10kg的Ni 0.63Co 0.05Mn 0.32(OH) 2加入搅拌机中持续搅拌2min，然后转移到离心机离心，再将离心后的前驱体，在120℃条件下烘干4小时，获得低表面能前体Ni 0.63Co 0.05Mn 0.32(OH) 2·0.03(CoOOH) 0.3(B 2O 3) 0.2·(ZrO 2) 0.5。 1) Put 12kg (CoOOH) 0.3 · (B 2 O 3 ) 0.2 · (ZrO 2 ) 0.5 sol (concentration: 3wt%) into the high-speed mixer, and under high-speed stirring (speed: 400rpm/min), add 10kg Add Ni 0.63 Co 0.05 Mn 0.32 (OH) 2 into the mixer and continue to stir for 2 minutes, then transfer to a centrifuge for centrifugation, and then dry the centrifuged precursor at 120°C for 4 hours to obtain a low surface energy precursor Ni 0.63 Co 0.05 Mn 0.32 (OH) 2 0.03 (CoOOH) 0.3 (B 2 O 3 ) 0.2 (ZrO 2 ) 0.5 .
2)将10kg前体Ni 0.63Co 0.05Mn 0.32(OH) 2·0.03(CoOOH) 0.3(B 2O 3) 0.2·(ZrO 2) 0.5与4.60kg  LiOH·H 2O和0.214kg Li 2CO 3机械混合后，放到气氛炉中，550℃烧结2h，然后升温至950℃烧结10h，从而得到块状产物： 2) Mix 10kg of precursor Ni 0.63 Co 0.05 Mn 0.32 (OH) 2 0.03(CoOOH) 0.3 (B 2 O 3 ) 0.2 (ZrO 2 ) 0.5 with 4.60kg LiOH H 2 O and 0.214kg Li 2 CO 3 After mechanical mixing, put it in an atmosphere furnace, sinter at 550°C for 2 hours, and then heat up to 950°C for 10 hours to obtain a block product:
LiNi 0.608Co 0.048Mn 0.31(Co 0.008B 0.011Zr 0.014)O 2； LiNi 0.608 Co 0.048 Mn 0.31 (Co 0.008 B 0.011 Zr 0.014 )O 2 ;
3)块状LiNi 0.608Co 0.048Mn 0.31(Co 0.08B 0.011Zr 0.014)O 2机械破碎成D50为5.0微米，具有单晶形貌，再与88.98g CoOOH、5.0g WO 3，2.0g Al 2O 3，25.8g LiOH·H 2O和6.45g Li 2O进行机械混合后进行在750℃下烧结8小时，得到具有低表面能晶面择优取向的所述正极材料： 3) Lumpy LiNi 0.608 Co 0.048 Mn 0.31 (Co 0.08 B 0.011 Zr 0.014 )O 2 is mechanically crushed into a D50 of 5.0 microns with a single crystal morphology, and then mixed with 88.98g CoOOH, 5.0g WO 3 , 2.0g Al 2 O 3. 25.8g LiOH·H 2 O and 6.45g Li 2 O were mechanically mixed and then sintered at 750°C for 8 hours to obtain the positive electrode material with preferred orientation of crystal planes with low surface energy:
LiNi 0.608Co 0.048Mn 0.31(Co 0.08B 0.011Zr 0.014)O 2·0.01Li(Co 0.95W 0.02Al 0.03)O 2。 LiNi 0.608 Co 0.048 Mn 0.31 (Co 0.08 B 0.011 Zr 0.014 )O 2 ·0.01Li(Co 0.95 W 0.02 Al 0.03 )O 2 .
其XRD显示其I(003)/I(012)为10.2，I(003)/I(110)为7.8。Its XRD shows that its I(003)/I(012) is 10.2, and I(003)/I(110) is 7.8.
性能测试：Performance Testing:
1、制备测试电池：1. Preparation of test battery:
以上述实施例1～3和市面买来的523NCM(镍钴锰三元材料)、712NCM、613NCM为正极材料，PVDF(聚偏氟乙烯)为粘结剂，活性碳为导电剂，三者的质量百分比为96：2：2，NMP(N-甲基吡咯烷酮)为溶剂，搅拌成浆料，利用涂布机将浆料均匀涂布在铝箔上，烘干后制成正极片，电解液为1.02mol/L的六氟磷酸锂，DMC(碳酸二甲酯)/EMC(碳酸甲乙酯)/PC(聚碳酸酯)为电解液溶剂，以石墨为负极，制成软包电池。523NCM (nickel-cobalt-manganese ternary material), 712NCM, and 613NCM bought in the market are used as positive electrode materials, PVDF (polyvinylidene fluoride) is used as a binding agent, and activated carbon is used as a conductive agent. The mass percentage is 96:2:2, NMP (N-methylpyrrolidone) is used as the solvent, stirred into a slurry, and the slurry is evenly coated on the aluminum foil with a coating machine, and the positive electrode sheet is made after drying, and the electrolyte is 1.02mol/L lithium hexafluorophosphate, DMC (dimethyl carbonate)/EMC (ethyl methyl carbonate)/PC (polycarbonate) as the electrolyte solvent, and graphite as the negative electrode to make a pouch battery.
将上述电池通过锂离子电池化成，待老化后，测试电池的放电容量，不同电流条件下的倍率性能、循环性能以及储存性。The above-mentioned battery is formed by a lithium-ion battery, and after aging, the discharge capacity of the battery, the rate performance, cycle performance and storage capacity under different current conditions are tested.
2、电化学性能测试条件：2. Electrochemical performance test conditions:
(1)放电容量：先以0.33C充电至4.5V，恒压至0.05C，在20℃下以0.1C倍率放电至2.8V，放电初始电压为4.5V；(1) Discharge capacity: first charge at 0.33C to 4.5V, constant voltage to 0.05C, discharge to 2.8V at a rate of 0.1C at 20°C, and the initial discharge voltage is 4.5V;
(2)倍率性能：在室温下分别将以0.33C恒流充电至4.5V，后恒压充电至0.05C；再分别以0.33C和4C恒流放电至2.8V，记录0.33C和4C的放电容量。(2) Rate performance: at room temperature, charge at 0.33C constant current to 4.5V, then charge at constant voltage to 0.05C; then discharge at 0.33C and 4C constant current to 2.8V, record the discharge at 0.33C and 4C capacity.
(3)常温循环性能：在2.8～4.5V的电压范围中，在25℃恒温箱中，以1C充电，1C放电循环至其容量保持率为80％；(3) Cycling performance at normal temperature: In the voltage range of 2.8-4.5V, in a constant temperature box at 25°C, charge at 1C, discharge at 1C until the capacity retention rate is 80%;
(4)高温循环性能：在2.8～4.5V的电压范围中，在45℃恒温箱中，以1C充电，1C放电循环至其容量保持率为80％；(4) High-temperature cycle performance: In the voltage range of 2.8-4.5V, in a 45°C incubator, charge at 1C, discharge at 1C until the capacity retention rate is 80%;
(5)高温循环性能：在2.8～4.5V的电压范围中，在45℃恒温箱中，以1C充电，1C放电循环至其容量保持率为80％；(5) High-temperature cycle performance: In the voltage range of 2.8-4.5V, in a 45°C incubator, charge at 1C, discharge at 1C until the capacity retention rate is 80%;
(6)高温储存性能：将电芯满充至4.5V，后放置于60℃的烘箱中烘烤30天，记录烘烤前后的电芯体积变化，记录体积变化率。(6) High-temperature storage performance: fully charge the cell to 4.5V, then place it in an oven at 60°C and bake for 30 days, record the volume change of the cell before and after baking, and record the volume change rate.
3、不同实施例和对比例的电化学性能测试如表1：3. The electrochemical performance tests of different embodiments and comparative examples are shown in Table 1:
表1Table 1
Figure PCTCN2022131114-appb-000001
Figure PCTCN2022131114-appb-000001
注：表1中的极片压实密度的数据为：(辊压后极片质量-未涂布极片质量)/极片面积/(辊压后极片厚度-未涂布极片厚度)；Note: The data of compaction density of pole piece in Table 1 is: (mass of pole piece after rolling - mass of uncoated pole piece) / area of pole piece / (thickness of pole piece after rolling - thickness of uncoated pole piece) ;
高温储存性能的数据为：(烘烤后电芯的体积-烘烤前电芯的体积)/烘烤前电芯的体积×100％；The data of high-temperature storage performance is: (volume of battery cell after baking - volume of battery cell before baking) / volume of battery cell before baking × 100%;
倍率性能的数据为：(4C倍率放电容量/0.33C倍率放电容量)×100％。The data of the rate performance is: (4C rate discharge capacity/0.33C rate discharge capacity)×100%.
由上表可知：在4.5V高电压下，实施例1的放电容量、4.5V循环性能、4.5V高温存储以及极片压实密度相对于对比样523NCM有明显的提高，倍率性能基本相当；在卷绕电芯设计条件下，单晶或类单晶的电池的极片压实密度基本是3.4g/cm 3，而本发明能提高到3.5g/cm 3。 It can be seen from the above table that: at a high voltage of 4.5V, the discharge capacity, 4.5V cycle performance, 4.5V high-temperature storage and pole piece compaction density of Example 1 are significantly improved compared with the comparison sample 523NCM, and the rate performance is basically the same; Under the design conditions of the winding battery core, the compacted density of the pole piece of the single crystal or similar single crystal battery is basically 3.4g/cm 3 , but the present invention can increase it to 3.5g/cm 3 .
此外，目前商用电池的循环电压为4.2-4.4V，而本发明能在4.5V下保持良好的循环性能。In addition, the current cycle voltage of commercial batteries is 4.2-4.4V, but the present invention can maintain good cycle performance at 4.5V.
实施例2的放电容量、高温循环性能、高温存储、极片压实密度以及倍率性能相对于对比样721NCM有明显提高；实施例3的放电容量、高温循环性能、高温存储、倍率性能以及极压实密度相对于对比样613NCM有明显的提高。这说明，本发明中提供的具有低表面择优取向的正极材料，有效地抑制材料在高电压循环过程结构的变化而造成的电化学性能恶化，且同时提高材料的压实密度，使得材料的综合性能提高。Compared with the comparative sample 721NCM, the discharge capacity, high temperature cycle performance, high temperature storage, pole piece compaction density and rate performance of Example 2 are significantly improved; the discharge capacity, high temperature cycle performance, high temperature storage, rate performance and extreme pressure of Example 3 Compared with the comparison sample 613NCM, the solid density has been significantly improved. This shows that the positive electrode material with low surface preferred orientation provided in the present invention can effectively inhibit the deterioration of electrochemical performance caused by the structure change of the material in the high-voltage cycle process, and at the same time improve the compaction density of the material, so that the comprehensive Improved performance.
以上仅为本发明的实施例，并非因此限制本发明的专利范围，凡是利用本发明说明书内 容所作的等同变换，或直接或间接运用在相关的技术领域，均同理包括在本发明的专利保护范围内。The above are only examples of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent transformations made by using the content of the description of the present invention, or directly or indirectly used in related technical fields, are equally included in the patent protection of the present invention. within range.

Claims (10)

  1. 一种正极材料，其特征在于：A positive electrode material, characterized in that:
    所述正极材料包括内层和外层；The positive electrode material includes an inner layer and an outer layer;
    所述内层包含LiNi xMn yCo z(Co aM b)O 2； The inner layer comprises LiNixMnyCoz ( CoaMb ) O2 ;
    所述外层包含Li(Co cN d)O 2，所述外层与内层中Li元素的摩尔比为A； The outer layer contains Li(Co c N d )O 2 , and the molar ratio of the Li element in the outer layer to the inner layer is A;
    所述Co aM b为含Co和M的氧化物混合溶胶、羟基氧化溶胶中的至少一种； The Co a M b is at least one of an oxide mixed sol containing Co and M, and an oxyhydroxide sol;
    其中，0.35≤x≤0.75，0.2≤y≤0.50，0.01<z<0.13，0<a≤0.05，0<b≤0.05；Among them, 0.35≤x≤0.75, 0.2≤y≤0.50, 0.01<z<0.13, 0<a≤0.05, 0<b≤0.05;
    x+y+z+a+b＝1，0<A≤0.03，0.65<c≤0.95，0.35<d≤0.05；x+y+z+a+b=1, 0<A≤0.03, 0.65<c≤0.95, 0.35<d≤0.05;
    M包括Mg、Al、Ti、Zr、Sr、Y、Ce、W、La、Sn、Mo、Fe、B或Si中的至少一种；M includes at least one of Mg, Al, Ti, Zr, Sr, Y, Ce, W, La, Sn, Mo, Fe, B or Si;
    N包括Al、Ti、W、B或Mg中的至少一种。N includes at least one of Al, Ti, W, B or Mg.
  2. 一种制备权利要求1所述的正极材料的方法，其特征在于：包括以下步骤：A method for preparing the positive electrode material according to claim 1, characterized in that: comprising the steps of:
    S1将所述Co aM b涂覆于前驱体表面，与部分锂源混合，烧结得到LiNi xMn yCo z(Co aM b)O 2； S1 Coating the Co a M b on the surface of the precursor, mixing with part of the lithium source, and sintering to obtain LiNi x Mny Co z (Co a M b )O 2 ;
    S2将S1得到的产物与含Co化合物、含N化合物、余量锂源混合后烧结，得到所述正极材料；S2 mixes the product obtained in S1 with the Co-containing compound, the N-containing compound, and the remaining lithium source, and then sinters to obtain the positive electrode material;
    所述前驱体包括Ni x+a+bCo yMn z(OH) 2； The precursor includes Ni x+a+b Co y Mnz (OH) 2 ;
    含N化合物包括含Al、Ti、W、B、Mg的氧化物、水合氧化物、羟基氧化物、金属酸锂化合物中的至少一种。The N-containing compound includes at least one of oxides, hydrated oxides, oxyhydroxides, and lithium metal oxide compounds containing Al, Ti, W, B, and Mg.
  3. 根据权利要求2所述的方法，其特征在于：The method according to claim 2, characterized in that:
    所述锂源包括碳酸锂、硝酸锂、氢氧化锂、氧化锂、草酸锂、乙酸锂中的至少一种。The lithium source includes at least one of lithium carbonate, lithium nitrate, lithium hydroxide, lithium oxide, lithium oxalate, and lithium acetate.
  4. 根据权利要求2所述的方法，其特征在于：The method according to claim 2, characterized in that:
    所述含Co化合物包括含Co氢氧化物、羟基氧化物、碳酸化物中的至少一种。The Co-containing compound includes at least one of Co-containing hydroxides, oxyhydroxides, and carbonates.
  5. 根据权利要求2所述的方法，其特征在于：The method according to claim 2, characterized in that:
    步骤S2中，所述LiNi xMn yCo z(Co aM b)O 2破碎成单晶或类单晶形貌后，再与所述含Co化合物、所述含N化合物、所述余量锂源混合。 In step S2, after the LiNi x Mn y Co z (Co a M b )O 2 is broken into a single crystal or a single crystal-like morphology, it is mixed with the Co-containing compound, the N-containing compound, the balance Lithium source mixed.
  6. 根据权利要求2所述的方法，其特征在于：The method according to claim 2, characterized in that:
    所述Co aM b与所述前驱体的质量比为8-20：10。 The mass ratio of the Co a M b to the precursor is 8-20:10.
  7. 根据权利要求2所述的方法，其特征在于：The method according to claim 2, characterized in that:
    步骤S1所述烧结为先在250-550℃下烧结，随后再进行升温烧结。The sintering in step S1 is first sintering at 250-550° C., and then sintering at elevated temperature.
  8. 根据权利要求7所述的方法，其特征在于：The method according to claim 7, characterized in that:
    步骤S1中所述升温烧结的温度为750-1050℃；The temperature for heating and sintering described in step S1 is 750-1050°C;
    步骤S1中所述升温烧结的时间为8-30h。The time for heating and sintering in step S1 is 8-30 hours.
  9. 根据权利要求2所述的方法，其特征在于：The method according to claim 2, characterized in that:
    S2中所述烧结为在450℃～850℃下烧结3h-10h。The sintering described in S2 is sintering at 450° C. to 850° C. for 3 hours to 10 hours.
  10. 如权利要求1所述的一种正极材料在电池中的应用。The application of a kind of cathode material as claimed in claim 1 in battery.
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