WO2022205668A1 - 一种含固态电解质的高镍三元复合正极及锂离子电池 - Google Patents

一种含固态电解质的高镍三元复合正极及锂离子电池 Download PDF

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WO2022205668A1
WO2022205668A1 PCT/CN2021/105916 CN2021105916W WO2022205668A1 WO 2022205668 A1 WO2022205668 A1 WO 2022205668A1 CN 2021105916 W CN2021105916 W CN 2021105916W WO 2022205668 A1 WO2022205668 A1 WO 2022205668A1
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positive electrode
nickel
ternary composite
solid electrolyte
composite positive
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French (fr)
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田军
陈彬
苏敏
韩笑
李凡群
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万向一二三股份公司
万向集团公司
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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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—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
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • 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 relates to the field of lithium batteries, in particular to a high-nickel ternary composite positive electrode containing a solid electrolyte and a lithium ion battery.
  • Lithium-ion batteries not only need to have high energy density and high power density, but also need to have excellent high temperature performance, long cycle life and high safety.
  • the current commercial lithium-ion batteries have low energy density, and it is difficult to meet both high energy density and high power density at the same time, which cannot meet the growing demand for electric vehicles. Therefore, the development of lithium-ion batteries with high energy density and high power density has become a hot spot of social research and the trend of industry development, which plays an important role in promoting the development of electric vehicles.
  • the energy density of a single battery needs to reach 400Wh/Kg in 2025. Combined with the performance comparison of existing batteries at various levels, it can be seen that the energy density of batteries at the material level and electrode level is still greatly improved. space.
  • lithium-ion battery cathode materials are of great help in improving the energy density of lithium-ion batteries, especially high-nickel ternary cathode materials, which can significantly improve the energy density of lithium-ion batteries.
  • the structural stability and thermal stability of the material decrease, resulting in a decrease in high-temperature cycle performance, high-temperature storage performance, and a significant decrease in safety.
  • the present invention provides a high-nickel ternary composite positive electrode containing a solid electrolyte and a lithium ion battery, and the lithium ion battery containing the high-nickel ternary composite positive electrode containing a solid electrolyte of the present invention can have high energy density at the same time. And high power density, lithium-ion battery rate, high temperature storage and cycle performance are improved, while ensuring the safety performance of the battery to meet the needs of power batteries.
  • the present invention provides a high-nickel ternary composite positive electrode containing a solid electrolyte, comprising a positive electrode current collector, a positive electrode material layer provided on the positive electrode current collector, and the positive electrode material layer is composed of a positive electrode active material, a positive electrode material layer, and a positive electrode material layer.
  • the positive electrode slurry of inorganic solid electrolyte, conductive agent and binder is cured.
  • the inorganic solid electrolyte is selected from Li 7 La 3 Zr 2 O 12 , Li 10 GeP 2 S 12 , Li 2 O-Al 2 O 3 -SiO 2 -P 2 O 5 -TiO 2 -GeO 2 , Li 2 O -Al 2 O 3 -SiO 2 -P 2 O 5 -TiO 2 , Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , Li 2 SP 2 S 5 , Li 2 OP 2 One or more of O 5 , Li 3.5 V 0.5 Ge 0.5 O 4 and Li 14 ZnGe 4 O 16 .
  • high nickel ternary cathode materials can significantly improve the energy density of lithium-ion batteries.
  • the structural stability and thermal stability of the material decrease, resulting in a decrease in high-temperature cycle performance, high-temperature storage performance, and a significant decrease in safety. Therefore, the present invention uses a high nickel ternary material as the positive electrode, which can first ensure that the battery has a high energy density, which can reach more than 300Wh/Kg, which can meet the current industrial needs.
  • the present invention introduces an inorganic solid electrolyte into the positive electrode, which can significantly improve the ionic conductivity and thermal stability of the composite positive electrode, effectively improve the battery rate, high-temperature storage and cycle performance, and at the same time improve the battery's performance. safety performance.
  • the introduction of an inorganic solid electrolyte into the cathode system can improve the mutual matching between the transport channel and the lithium ion radius, reduce the porosity, improve the density, and thus improve the lithium ion conductivity. lower, so that more capacity can be exerted.
  • the introduction of an inorganic solid electrolyte can improve the solid/solid interface contact, improve the wettability of the electrolyte, increase the migration rate of lithium ions, and reduce the internal resistance of the battery, thereby improving the battery cycle performance.
  • the inorganic solid electrolyte has good electrochemical stability and thermal stability. Excellent, adding it to the positive electrode sheet can improve the thermal stability of the positive electrode and further improve the safety performance of the battery.
  • the inorganic solid electrolyte is selected from Li 7 La 3 Zr 2 O 12 , Li 10 GeP 2 S 12 , Li 2 O-Al 2 O 3 -SiO 2 -P 2 O 5 -TiO 2 -GeO 2 , Li 2 O -Al 2 O 3 -SiO 2 -P 2 O 5 -TiO 2 , Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , Li 2 SP 2 S 5 , Li 2 OP 2 One or more of O 5 , Li 3.5 V 0.5 Ge 0.5 O 4 and Li 14 ZnGe 4 O 16 .
  • the above-mentioned materials are commonly used as solid-state electrolytes of solid-state batteries in the prior art (existing in the solid-state electrolyte layer instead of the positive electrode), and their function is to allow lithium ions to be smoothly conducted between the positive and negative electrodes, and its room temperature ionic conductivity is high. It has the characteristics of high thermal stability, good safety performance, and wide electrochemical stability window (up to 5V or more). During the charging and discharging process of lithium batteries, lithium ions are intercalated and deintercalated back and forth between the two electrodes. As a positive electrode additive, it is required to be an effective dopant, which can improve the ionic conductivity without destroying the chemical and electrochemical stability.
  • the migration rate of lithium ions is improved, which facilitates the movement of lithium ions between the positive electrode and the negative electrode, improves the lithium ion conductivity, reduces the polarization and internal resistance of the battery, and increases the rate of the battery. , cycle performance and safety performance are improved.
  • the dry powder weight ratio of the positive electrode active material, the inorganic solid electrolyte, the conductive agent, and the binder is 90-98:0.1-5:1-3:1-2.
  • the particle size of the inorganic solid electrolyte is less than 1 ⁇ m.
  • the positive electrode active material is high nickel nickel cobalt manganese or high nickel cobalt aluminum whose surface is coated with a coating layer containing Li 2+X C 1-X B X O 3 , where 0 ⁇ X ⁇ 1.
  • the present invention uses Li 2+X C 1-X B X O 3 material obtained by sintering lithium borate and lithium carbonate as a coating agent.
  • Li 2+X C 1- X B X O 3 can significantly improve the lithium ion conductivity of the coated ternary cathode material, and improve the influence of the introduction of B element on the reduction of the ionic conductivity of the material.
  • the coating layer in the present invention can effectively slow down the occurrence of side reactions between the ternary positive electrode material and the electrolyte in the battery, improve its cycle performance, and prolong the battery life.
  • the cladding layer also includes other cladding materials selected from one or more of aluminum oxide, magnesium oxide, boron oxide and tungsten oxide.
  • the preparation method of the high-nickel-nickel-cobalt-manganese or high-nickel-cobalt-aluminum whose surface is coated with a coating layer containing Li 2+X C 1-X B X O 3 includes the following steps:
  • Lithium borate and lithium carbonate are uniformly mixed according to the molar ratio of B atoms and C atoms and then sintered to obtain Li 2+X C 1-X B X O 3 ;
  • the present invention adopts a three-time calcination process: firstly, a high-nickel-nickel-cobalt-manganese or high-nickel-nickel-cobalt-aluminum ternary positive electrode material is obtained by one calcination; Modified with nickel-nickel-cobalt-manganese or high-nickel-cobalt-aluminum, dense oxides that can react with Li 2+X C 1-X B X O 3 coating agent are generated on the surface; Manganese or high nickel nickel cobalt aluminum is used for coating, and the reaction between the coating agent and the oxide formed on the surface of the ternary positive electrode material during secondary calcination is
  • a coating layer is formed by coating on the surface of the ternary material, and the coating layer is not easy to fall off from the surface of the ternary material. Therefore, the present invention simultaneously improves the capacity performance and cycle performance of the battery under the combined action of the coating agent and the coating process.
  • the primary calcination temperature is 700-900° C.
  • the calcination time is 18-26 h.
  • the alkaline solution is selected from one or more of lithium hydroxide solution, lithium carbonate solution and lithium nitrate solution, and the concentration of the alkaline solution is 0.1-5 mol/L; stirring time 0.5 ⁇ 5h, vacuum drying temperature is 100 ⁇ 300°C, drying time is 10 ⁇ 24h; the environment of secondary calcination is air and/or CO 2 atmosphere, the secondary calcination temperature is 200 ⁇ 500°C, and the calcination time is 2 ⁇ 5h.
  • the sintering temperature is 800-900°C, and the sintering time is 18-26h;
  • the mass of Li 2+x C 1-x B x O 3 is 500-5000 ppm of the mass of the secondary calcined sample powder; the addition amount of other coating materials is 500 to 5000 ppm of the secondary calcined sample powder mass 400 ⁇ 20000ppm; the third calcination temperature is 600 ⁇ 800°C, and the calcination time is 18 ⁇ 26h.
  • the conductive agent is selected from at least one of graphene, carbon nanotubes, conductive carbon fibers, conductive carbon black, conductive graphite and acetylene black.
  • the binder is selected from one or more of polyvinylidene fluoride, polyimide and polyacrylonitrile.
  • the present invention provides a lithium ion battery containing the above-mentioned high-nickel ternary composite positive electrode.
  • the present invention uses a high nickel ternary material as the positive electrode, which can ensure that the battery has a high energy density.
  • the present invention introduces an inorganic solid electrolyte into the positive electrode, which can significantly improve the ionic conductivity and thermal stability of the composite positive electrode, effectively improve the battery rate, high-temperature storage and cycle performance, and at the same time improve the battery's performance. safety performance.
  • the present invention uses Li 2+X C 1-X B X O 3 material obtained after sintering lithium borate and lithium carbonate as a coating agent, which can significantly improve the lithium ion conductivity of the coated ternary positive electrode material, The influence of the introduction of B element on the reduction of the ionic conductivity of the material is improved.
  • the surface of the ternary material is modified by an alkaline solution before coating, and a dense oxide that can react with the Li 2+X C 1-X B X O 3 coating agent is generated on the surface of the ternary material, Therefore, the Li 2+X C 1-X B X O 3 coating agent can effectively coat the surface of the ternary material, and the formed coating layer is not easy to fall off; Battery capacity performance and cycle performance.
  • Fig. 1 is the SEM image of the composite positive electrode obtained in Example 3 of the present invention.
  • a high-nickel ternary composite positive electrode containing a solid electrolyte comprising a positive electrode current collector, a positive electrode material layer provided on the positive electrode current collector, and the positive electrode material layer is composed of a positive electrode active material, an inorganic solid electrolyte, a conductive agent and a viscosity.
  • the positive electrode slurry of the binder is cured.
  • the dry powder weight ratio of positive active material, inorganic solid electrolyte, conductive agent and binder is 90-98:0.1-5:1-3:1-2.
  • the particle size of the inorganic solid electrolyte is less than 1 ⁇ m, and is selected from Li 7 La 3 Zr 2 O 12 , Li 10 GeP 2 S 12 , Li 2 O-Al 2 O 3 -SiO 2 -P 2 O 5 -TiO 2 -GeO 2.
  • Li 2 O-Al 2 O 3 -SiO 2 -P 2 O 5 -TiO 2 Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , Li 2 SP 2 S 5
  • the conductive agent is selected from at least one of graphene, carbon nanotubes, conductive carbon fibers, conductive carbon black, conductive graphite and acetylene black.
  • the binder is selected from one or more of polyvinylidene fluoride, polyimide and polyacrylonitrile.
  • the positive electrode active material is coated with a coating layer containing Li 2+X C 1-X B X O 3 and other coating materials (alumina, magnesium oxide, boron oxide, tungsten oxide) on the surface.
  • a coating layer containing Li 2+X C 1-X B X O 3 and other coating materials alumina, magnesium oxide, boron oxide, tungsten oxide
  • Lithium borate and lithium carbonate are uniformly mixed according to the molar ratio of B atoms and C atoms, and then sintered (800 ⁇ 900°C, 18 ⁇ 26h) to obtain Li 2+x C 1-x B x O 3 ;
  • a lithium ion battery containing the above-mentioned high nickel ternary composite positive electrode containing the above-mentioned high nickel ternary composite positive electrode.
  • the coated positive and negative electrode pieces are cut and punched, and then the positive and negative electrode pieces are separated by a diaphragm, packaged with an aluminum-plastic film, injected with a self-made electrolyte, fully infiltrated, and converted into a volume to obtain lithium ion battery.
  • the coated positive and negative electrode pieces are cut and punched, and then the positive and negative electrode pieces are separated by a diaphragm, packaged with an aluminum-plastic film, injected with a self-made electrolyte, fully infiltrated, and converted into a volume to obtain lithium ion battery.
  • the coated positive and negative electrode pieces are cut and punched, and then the positive and negative electrode pieces are separated by a diaphragm, packaged with an aluminum-plastic film, injected with a self-made electrolyte, fully infiltrated, and converted into a volume to obtain lithium ion battery.
  • the coated positive and negative electrode pieces are cut and punched, and then the positive and negative electrode pieces are separated by a diaphragm, packaged with an aluminum-plastic film, injected with a self-made electrolyte, fully infiltrated, and converted into a volume to obtain lithium ion battery.
  • the coated positive and negative electrode pieces are cut and punched, and then the positive and negative electrode pieces are separated by a diaphragm, packaged with an aluminum-plastic film, injected with a self-made electrolyte, fully infiltrated, and converted into a volume to obtain lithium ion battery.
  • the positive electrode active material is a high-nickel-nickel-cobalt-manganese whose surface is coated with a coating layer containing Li 2.5 C 0.5 B 0.5 O 3 and magnesium oxide), and its preparation method is:
  • Lithium borate and lithium carbonate are uniformly mixed according to the molar ratio of B atoms and C atoms as 1:1, and sintered at 850° C. for 24 hours to obtain Li 2.5 C 0.5 B 0.5 O 3 coating agent;
  • the secondary calcined sample powder is uniformly mixed with Li 2.5 C 0.5 B 0.5 O 3 coating agent and magnesium oxide, and then calcined for three times .
  • the mass of magnesium oxide is 3000ppm
  • the mass of magnesium oxide is 10000ppm of the mass of the secondary calcined sample powder
  • the tertiary calcination temperature is 800 °C
  • the calcination time is 24h to obtain the coated ternary cathode material.
  • the coated positive and negative electrode pieces are cut and punched, and then the positive and negative electrode pieces are separated by a diaphragm, packaged with an aluminum-plastic film, injected with a self-made electrolyte, fully infiltrated, and converted into a volume to obtain lithium ion battery.
  • the lithium-ion batteries prepared in Examples 3, 6 and Comparative Example 1 were subjected to the following performance test conditions:
  • High temperature storage performance test put the battery in a 60°C environment, store it for 30 days, 60 days, and 90 days, then discharge at 1/3C, and then charge and discharge 3 times at 1/3C, and calculate the final discharge capacity and initial The capacity ratio is obtained to obtain the capacity recovery rate.
  • Rate test Under the environment of 25°C, charge the battery to full charge at 0.333C current, constant current and constant voltage, and then discharge at 0.333C, 1C, 2C, and 3C respectively.
  • Cyclic performance test conditions the number of cycles for the battery to be charged and discharged at 1C/1C at a temperature of 45°C until the capacity reaches 80% of the initial capacity.
  • FIG. 1 is a SEM image of the composite positive electrode obtained in Example 3 of the present invention.
  • Figures 2 and 3 are the high-temperature storage capacity recovery rate and DCR growth curves of the batteries prepared in Examples 3 and 6 and Comparative Example 1.
  • Example 6 exhibits the best high-temperature storage performance. After 90 days of high-temperature storage, the capacity recovery rate is as high as 97.67% , DCR increased by only 3.22%, Example 3 exhibited good high-temperature storage performance, its 90d capacity recovery rate was 93.95%, and DCR growth was 7.89, while the high-temperature storage performance of Comparative Example 90d was significantly worse than Examples 3 and 6, and its capacity recovery was The rate is only 86.33%, and the DCR increase is as high as 10.38%, indicating that the coating of the cathode material and the addition of the inorganic solid electrolyte can significantly improve the high-temperature storage.
  • the coating of the cathode material can block the electrolyte and the cathode.
  • the inorganic solid electrolyte itself has good thermal stability, which can improve the wettability of the electrolyte in the positive electrode and reduce the impedance, thereby improving the high temperature storage performance.
  • Figure 4 shows the rate discharge diagrams of the batteries prepared in Examples 3 and 6 and Comparative Example 1. It can be seen from the figure that Example 6 exhibits more excellent rate performance, especially at 3C rate discharge, its capacity retention rate can be as high as 94.23 %, the discharge rate of Example 3 is comparable to that of the Example, and its 3C discharge capacity retention rate reaches 92.08%, while the discharge capacity retention rate of Comparative Example 1 from 1C to 3C is significantly lower than that of Examples 3 and 6, only 73.25% , which is due to the addition of inorganic solid electrolytes in Examples 3 and 6, which improves the lithium ion migration rate, thereby improving the rate discharge performance of the battery.
  • Figure 5 shows the high temperature cycle curves of Examples 3 and 6 and Comparative Example 1. It can be seen from the figure that Example 6 exhibits excellent high temperature cycle performance. When its capacity reaches 80% of the initial capacity, the number of cycles is as high as 1100 cycles. 3 is 852 circles, and the comparative example has only 752 circles. This is because the positive electrode of Example 6 is coated, which alleviates the dissolution of metal ions in the electrolyte and deposits on the surface of the negative electrode, thereby improving the high-temperature cycle performance. In addition, the addition of inorganic solid electrolyte Further improve ion migration rate and thermal stability, and further improve high temperature performance.
  • the raw materials and equipment used in the present invention are the common raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are the conventional methods in the art.

Abstract

本发明涉及锂电池领域，公开了一种含固态电解质的高镍三元复合正极及锂离子电池，复合正极包括正极集流体、设有正极集流体上的正极材料层，正极材料层由含有正极活性物质、无机固态电解质、导电剂和粘结剂的正极浆料固化而成。含有本发明高镍三元复合正极的锂离子电池可同时具有高能量密度及高功率密度，锂离子电池倍率、高温存储及循环性能得到改善，同时保证电池的安全性能，以满足动力电池的需求。

Description

一种含固态电解质的高镍三元复合正极及锂离子电池 技术领域
本发明涉及锂电池领域，尤其涉及一种含固态电解质的高镍三元复合正极及锂离子电池。
背景技术
随着电动汽车的快速发展，对锂离子电池的要求也越来越高。锂离子电池不仅需要具有高能量密度和高功率密度，还需要有优异的高温性能、长循环寿命和高安全性性等。然而，现阶段商业化锂离子电池能量密度较低，而且难以同时满足既高能量密度又高功率密度，无法满足电动车日益增长的需求。因此，开发高能量密度和高功率密度锂离子电池成为当今社会研究的热点及行业发展的趋势，这对于推进电动车发展进程具有重要作用。
基于动力电池技术发展规划目标，2025年单体电池能量密度需要达到400Wh/Kg，结合现有的电池各个层次性能对比，可以看出在材料层面和电极层面电池的能量密度还有很大的提升空间。锂离子电池正极材料作为电池能量的来源和载体，对于提升锂离子电池能量密度有很大帮助，尤其是高镍三元正极材料，可显著提升锂离子电池能量密度。然而，随着镍含量的提高，材料的结构稳定性及热稳定性降低，导致高温循环性能、高温存储性能下降，同时安全性也大幅度降低。为了提高电池功率，通常选择提高导电剂的用量或降低面密度，相对应的是降低了活性物质在锂离子电池中的占比，降低了锂离子电池的能量密度。因此，为了同时满足对锂离子电池能量密度及高功率密度的需求，亟需提高高镍三元锂离子电池的倍率、高温存储及循环、安全性能，以推进电动车大规模应用。
发明内容
为了解决上述技术问题，本发明提供了一种含固态电解质的高镍三元复合正极及锂离子电池，含有本发明含固态电解质的高镍三元复合正极的锂离子电池可同时具有高能量密度及高功率密度，锂离子电池倍率、高温存储及循环性能得到改善，同时保证电池的安全性能，以满足动力电池的需求。
本发明的具体技术方案为：
第一方面，本发明提供了一种含固态电解质的高镍三元复合正极，包括正极集流体、设有所述正极集流体上的正极材料层，所述正极材料层由含有正极活性物质、无机固态电解质、导电剂和粘结剂的正极浆料固化而成。
所述正极活性物质选自高镍镍钴锰LiNi xCo yMn zO 2或高镍镍钴铝LiNi xCo yAl zO 2中的一种或多种，其中0.6≤x＜1.0，0＜y＜0.2，x+y+z＝1。
所述的无机固态电解质选自Li 7La 3Zr 2O 12、Li 10GeP 2S 12、Li 2O-Al 2O 3-SiO 2-P 2O 5-TiO 2-GeO 2、Li 2O-Al 2O 3-SiO 2-P 2O 5-TiO 2、Li 6.75La 3Zr 1.75Ta 0.25O 12、Li 9.54Si 1.74P 1.44S 11.7Cl 0.3、Li 2S-P 2S 5、Li 2O-P 2O 5、Li 3.5V 0.5Ge 0.5O 4和Li 14ZnGe 4O 16中的一种或多种。
如背景技术中所述，高镍三元正极材料可显著提升锂离子电池能量密度。然而，随着镍含量的提高，材料的结构稳定性及热稳定性降低，导致高温循环性能、高温存储性能下降，同时安全性也大幅度降低。为此，本发明以高镍三元材料作为正极，可先确保电池具备高能量密度，可达300Wh/Kg以上，可满足现阶段工业需求。同时为了解决高镍所带来的缺陷，本发明在正极中引入无机固态电解质，可明显提高复合正极的离子导电率及热稳定性，有效改善电池倍率、高温存储及循环性能，同时提高电池的安全性能。
具体地，在正极体系中引入无机固态电解质，可以提高传输通道与锂离子半径的相互匹配性，降低孔隙率，提高致密度，从而提高锂离子电导率，在高倍率放电条件下，电池极化降低，从而可以发挥出更多的容量。引入无机固态电解质可以改善固/固界面接触性，提高电解液浸润性，提升锂离子的迁移速率，降低电池内阻，从而提高电池循环性能，同时无机固态电解质电化学稳定性好、热稳定性优异，添加至正极极片中，可提高正极热稳定性，进一步提高电池的安全性能。
本发明中无机固态电解质选自Li 7La 3Zr 2O 12、Li 10GeP 2S 12、Li 2O-Al 2O 3-SiO 2-P 2O 5-TiO 2-GeO 2、Li 2O-Al 2O 3-SiO 2-P 2O 5-TiO 2、Li 6.75La 3Zr 1.75Ta 0.25O 12、Li 9.54Si 1.74P 1.44S 11.7Cl 0.3、Li 2S-P 2S 5、Li 2O-P 2O 5、Li 3.5V 0.5Ge 0.5O 4和Li 14ZnGe 4O 16中的一种或多种。
上述材料在现有技术中常用作固态电池的固态电解质(存在于固态电解质层中而非正极中)，作用是让锂离子在正负电极之间顺利地传导，其室温离子电导率高，同时具有热稳定高、安全性能好、电化学稳定窗口宽(达5V以上)的特点。在锂电池充放电过程中，锂离子在两个电极之间往返嵌入和脱出。作为正极添加剂，要求是一种有效的掺杂剂，既能提高离子电导率，又不会破坏化学和电化学稳定性，本发明团队通过研究发现上述几种材料可以很好的满足这些条件，将上述材料添加到正极后，锂离子的迁移速率得到提升，有助于锂离子在正极和负极之间的移动工作，提高了锂离子电导率，降低电池极化和内阻，对电池的倍率、循环性能和安全性能有改善的作用。
作为优选，所述正极活性物质、无机固态电解质、导电剂、粘结剂的干粉重量比为90-98:0.1-5:1-3:1-2。
作为优选，所述无机固态电解质的粒径小于1μm。
作为优选，所述正极活性物质为表面包覆有含Li 2+XC 1-XB XO 3的包覆层的高镍镍钴锰或高镍镍钴铝，其中0<X<1。
本发明使用硼酸锂与碳酸锂烧结后得到的Li 2+XC 1-XB XO 3材料作为包覆剂，与现有的硼酸盐包覆剂相比，Li 2+XC 1-XB XO 3可以显著提升包覆后的三元正极材料的锂离子电导率，改善了引入B元素后对材料离子电导率降低的影响。并且，本发明中的包覆层能够有效减缓三元正极材料与电池中电解质之间的副反应发生，提升其循环性能，延长电池寿命。
作为优选，所述包覆层中还包括其他包覆材料，选自氧化铝，氧化镁，氧化硼和氧化钨中的一种或几种。
作为优选，所述表面包覆有含Li 2+XC 1-XB XO 3的包覆层的高镍镍钴锰或高镍镍钴铝的制备方法包括如下步骤：
(1)将高镍镍钴锰或高镍镍钴铝的前驱体混合，搅拌均匀得到粉末材料，将粉末材料进行一次煅烧，粉碎后得到一次煅烧样品粉末；
(2)将一次煅烧样品粉末分散到碱液中，搅拌使其充分润湿，抽滤后真空干燥，再进行二次煅烧，得到二次煅烧样品粉末；
(3)将硼酸锂与碳酸锂按B原子和C原子的摩尔比混合均匀后烧结，制得Li 2+XC 1-XB XO 3；
(4)将二次煅烧样品粉末与Li 2+XC 1-XB XO 3以及其他包覆材料混合均匀后进行三次煅烧，得到表面包覆有含Li 2+XC 1-XB XO 3的包覆层的高镍镍钴锰或高镍镍钴铝。
为了使本发明中的Li 2+XC 1-XB XO 3可以有效包覆在高镍镍钴锰或高镍镍钴铝表面，形成与高镍镍钴锰或高镍镍钴铝紧密结合、不易脱落的包覆层，本发明采用三次煅烧工艺：先通过一次煅烧制得高镍镍钴锰或高镍镍钴铝三元正极材料；然后通过二次煅烧，利用碱性溶液对高镍镍钴锰或高镍镍钴铝进行改性，在其表面生成可以与Li 2+XC 1-XB XO 3包覆剂反应的致密氧化物；最后通过三次煅烧对高镍镍钴锰或高镍镍钴铝进行包覆，利用包覆剂与二次煅烧时在三元正极材料表面形成的氧化物的反应，使Li 2+XC 1-XB XO 3包覆剂牢固包覆在三元材料表面形成包覆层，且包覆层不易从三元材料表面脱落。因此，本发明在包覆剂和包覆工艺的共同作用下，同时提升了电池的容量性能及循环性能。
作为优选，步骤(1)中，一次煅烧温度为700～900℃，煅烧时间18～26h。
作为优选，步骤(2)中，所述碱液选自氢氧化锂溶液、碳酸锂溶液和硝酸锂溶液中的一种或几种，所述碱液的浓度为0.1～5mol/L；搅拌时间0.5～5h，真空干燥温度100～300℃，干燥时间10～24h；二次煅烧的环境为空气和/或CO 2气氛，二次煅烧温度为200～500℃，煅烧 时间2～5h。
作为优选，步骤(3)中，烧结温度800～900℃，烧结时间18～26h；
作为优选，步骤(4)中，Li 2+xC 1-xB xO 3的质量为二次煅烧样品粉末质量的500～5000ppm；其他包覆材料的添加量为二次煅烧样品粉末质量的400～20000ppm；三次煅烧温度为600～800℃，煅烧时间18～26h。
作为优选，所述导电剂选自石墨烯、碳纳米管、导电碳纤维、导电炭黑、导电石墨和乙炔黑中的至少一种。
作为优选，所述粘结剂选自聚偏氟乙烯、聚酰亚胺和聚丙腈中的一种或多种。
第二方面，本发明提供了一种含有上述高镍三元复合正极的锂离子电池。
与现有技术对比，本发明的有益效果是：
(1)本发明以高镍三元材料作为正极，可确保电池具备高能量密度。同时为解决高镍所带来的缺陷，本发明在正极中引入无机固态电解质，可明显提高复合正极的离子导电率及热稳定性，有效改善电池倍率、高温存储及循环性能，同时提高电池的安全性能。
(2)本发明使用硼酸锂与碳酸锂烧结后得到的Li 2+XC 1-XB XO 3材料作为包覆剂，可显著提升包覆后的三元正极材料的锂离子电导率，改善了引入B元素后对材料离子电导率降低的影响。
(3)在包覆前先通过碱性溶液对三元材料表面进行改性，在三元材料表面生成可以与Li 2+XC 1-XB XO 3包覆剂反应的致密氧化物，从而使Li 2+XC 1-XB XO 3包覆剂可以有效包覆在三元材料表面，形成的包覆层不易脱落；在包覆剂和包覆工艺的共同作用下，提升了电池的容量性能和循环性能。
附图说明
图1为本发明实施例3所得复合正极的SEM图；
图2为本发明实施例3、6和对比例1制备所得电池的高温存储容量恢复率曲线；
图3为本发明实施例3、6和对比例1所得电池的DCR增长曲线；
图4本发明实施例3、6和对比例1所得电池的电池倍率放电曲线；
图5本发明实施例3、6和对比例1所得电池的实施例3和6以及对比例1高温循环曲线。
具体实施方式
下面结合实施例对本发明作进一步的描述。
总实施例
一种含固态电解质的高镍三元复合正极，包括正极集流体、设有所述正极集流体上的正极材 料层，所述正极材料层由含有正极活性物质、无机固态电解质、导电剂和粘结剂的正极浆料固化而成。正极活性物质、无机固态电解质、导电剂、粘结剂的干粉重量比为90-98:0.1-5:1-3:1-2。
其中，所述正极活性物质选自高镍镍钴锰LiNi xCo yMn zO 2或高镍镍钴铝LiNi xCo yAl zO 2中的一种或多种，其中0.6≤x＜1.0，0＜y＜0.2，x+y+z＝1。所述的无机固态电解质粒径小于1μm，选自Li 7La 3Zr 2O 12、Li 10GeP 2S 12、Li 2O-Al 2O 3-SiO 2-P 2O 5-TiO 2-GeO 2、Li 2O-Al 2O 3-SiO 2-P 2O 5-TiO 2、Li 6.75La 3Zr 1.75Ta 0.25O 12、Li 9.54Si 1.74P 1.44S 11.7Cl 0.3、Li 2S-P 2S 5、Li 2O-P 2O 5、Li 3.5V 0.5Ge 0.5O 4和Li 14ZnGe 4O 16中的一种或多种。所述导电剂选自石墨烯、碳纳米管、导电碳纤维、导电炭黑、导电石墨和乙炔黑中的至少一种。所述粘结剂选自聚偏氟乙烯、聚酰亚胺和聚丙腈中的一种或多种。
可选地，所述正极活性物质为表面包覆有含Li 2+XC 1-XB XO 3和其他包覆材料(氧化铝、氧化镁、氧化硼、氧化钨)的包覆层的高镍镍钴锰或高镍镍钴铝，其中0<X<1。其制备方法为：
(1)将高镍镍钴锰或高镍镍钴铝的前驱体混合，搅拌均匀得到粉末材料，将粉末材料进行一次煅烧(700～900℃，18～26h)，粉碎后得到一次煅烧样品粉末；
(2)将一次煅烧样品粉末分散到0.1～5mol/L的碱液(氢氧化锂溶液、碳酸锂溶液、硝酸锂溶液)中，搅拌0.5～5h使其充分润湿，抽滤后100～300℃真空干燥10～24h，再进行二次煅烧(空气和/或CO 2气氛，200～500℃，2～5h)，得到二次煅烧样品粉末；
(3)将硼酸锂与碳酸锂按B原子和C原子的摩尔比混合均匀后烧结(800～900℃，18～26h)，制得Li 2+xC 1-xB xO 3；
(4)将二次煅烧样品粉末与Li 2+XC 1-XB XO 3以及其他包覆材料混合均匀后进行三次煅烧(600～800℃，18～26h)，得到表面包覆有含Li 2+XC 1-XB XO 3的包覆层的高镍镍钴锰或高镍镍钴铝。其中Li 2+XC 1-XB XO 3的质量为二次煅烧样品粉末质量的500～5000ppm；其他包覆材料的添加量为二次煅烧样品粉末质量的400～20000ppm.
一种含有上述高镍三元复合正极的锂离子电池。
实施例1
将1.5份PVDF搅拌至透明状胶液，添加1.3份碳纳米管/导电炭黑混合物，搅拌均匀，然后加入97.2份NCM811，继续搅拌，随后添加0.1份无机固态电解质Li 2O-Al 2O 3-SiO 2-P 2O 5-TiO 2-GeO，搅拌分散均匀，随后涂覆在铝集流体表面，烘干待用；
将1.3份CMC搅拌至透明状，添加1份导电石墨，搅拌均匀，然后添加96份人造石墨，继 续搅拌，随后加入1.7份丁苯橡胶乳液，搅拌分散均匀，均匀涂覆在负极集流体表面，烘干待用；
将涂覆后的正负极片进行分切、冲片，然后正极极片和负极极片通过隔膜隔开，采用铝塑膜封装，注入自制电解液，充分浸润，化成分容，制得锂离子电池。
实施例2
将1.5份PVDF搅拌至透明状胶液，添加1.3份碳纳米管/导电炭黑混合物，搅拌均匀，然后加入96.7份NCM811，继续搅拌，随后添加0.5份无机固态电解质Li 2O-Al 2O 3-SiO 2-P 2O 5-TiO 2-GeO，搅拌分散均匀，随后涂覆在铝集流体表面，烘干待用；
将1.3份CMC搅拌至透明状，添加1份导电石墨，搅拌均匀，然后添加96份人造石墨，继续搅拌，随后加入1.7份丁苯橡胶乳液，搅拌分散均匀，均匀涂覆在负极集流体表面，烘干待用；
将涂覆后的正负极片进行分切、冲片，然后正极极片和负极极片通过隔膜隔开，采用铝塑膜封装，注入自制电解液，充分浸润，化成分容，制得锂离子电池。
实施例3
将1.5份PVDF搅拌至透明状胶液，添加1.3份碳纳米管/导电炭黑混合物，搅拌均匀，然后加入96.2份NCM811，继续搅拌，随后添加1份无机固态电解质Li 2O-Al 2O 3-SiO 2-P 2O 5-TiO 2-GeO，搅拌分散均匀，随后涂覆在铝集流体表面，烘干待用；
将1.3份CMC搅拌至透明状，添加1份导电石墨，搅拌均匀，然后添加96份人造石墨，继续搅拌，随后加入1.7份丁苯橡胶乳液，搅拌分散均匀，均匀涂覆在负极集流体表面，烘干待用；
将涂覆后的正负极片进行分切、冲片，然后正极极片和负极极片通过隔膜隔开，采用铝塑膜封装，注入自制电解液，充分浸润，化成分容，制得锂离子电池。
实施例4
将1.5份PVDF搅拌至透明状胶液，添加1.3份碳纳米管/导电炭黑混合物，搅拌均匀，然后加入94.2份NCM811，继续搅拌，随后添加3份无机固态电解质Li 2O-Al 2O 3-SiO 2-P 2O 5-TiO 2-GeO，搅拌分散均匀，随后涂覆在铝集流体表面，烘干待用；
将1.3份CMC搅拌至透明状，添加1份导电石墨，搅拌均匀，然后添加96份人造石墨，继续搅拌，随后加入1.7份丁苯橡胶乳液，搅拌分散均匀，均匀涂覆在负极集流体表面，烘干待用；
将涂覆后的正负极片进行分切、冲片，然后正极极片和负极极片通过隔膜隔开，采用铝塑膜 封装，注入自制电解液，充分浸润，化成分容，制得锂离子电池。
实施例5
将1.5份PVDF搅拌至透明状胶液，添加1.3份碳纳米管/导电炭黑混合物，搅拌均匀，然后加入92.2份NCM811，继续搅拌，随后添加5份无机固态电解质Li 2O-Al 2O 3-SiO 2-P 2O 5-TiO 2-GeO，搅拌分散均匀，随后涂覆在铝集流体表面，烘干待用；
将1.3份CMC搅拌至透明状，添加1份导电石墨，搅拌均匀，然后添加96份人造石墨，继续搅拌，随后加入1.7份丁苯橡胶乳液，搅拌分散均匀，均匀涂覆在负极集流体表面，烘干待用；
将涂覆后的正负极片进行分切、冲片，然后正极极片和负极极片通过隔膜隔开，采用铝塑膜封装，注入自制电解液，充分浸润，化成分容，制得锂离子电池。
实施例6
与实施例3的区别在于：正极活性物质为表面包覆有含Li 2.5C 0.5B 0.5O 3和氧化镁)的包覆层的高镍镍钴锰，其制备方法为：
(1)将NCM811前驱体(Ni:Co:Mn摩尔比为8:1:1)与碳酸锂混合，搅拌均匀得到粉末材料，NCM811与碳酸锂的摩尔比为1:1.1；将粉末材料进行一次煅烧，煅烧温度800℃，煅烧时间24h，粉碎后得到一次煅烧样品粉末；
(2)将一次煅烧样品粉末分散到2mol/L碳酸锂溶液中，搅拌3h使其充分润湿，抽滤后在真空环境下200℃干燥12h，再进行二次煅烧，二次煅烧温度300℃，煅烧时间3h，得到二次煅烧样品粉末；
(3)将硼酸锂与碳酸锂按B原子和C原子的摩尔比为1:1混合均匀，850℃下烧结24h得到Li 2.5C 0.5B 0.5O 3包覆剂；
(4)将二次煅烧样品粉末与Li 2.5C 0.5B 0.5O 3包覆剂及氧化镁混合均匀后进行三次煅烧，Li 2.5C 0.5B 0.5O 3包覆剂的质量为二次煅烧样品粉末质量的3000ppm，氧化镁的质量为二次煅烧样品粉末质量的10000ppm，三次煅烧温度为800℃，煅烧时间24h，得到包覆后的三元正极材料。
对比例1
将1.5份PVDF搅拌至透明状胶液，添加1.3份碳纳米管/导电炭黑混合物，搅拌均匀，然后加入97.2份NCM811，搅拌分散均匀，随后涂覆在铝集流体表面，烘干待用；
将1.3份CMC搅拌至透明状，添加1份导电石墨，搅拌均匀，然后添加96份人造石墨，继续搅拌，随后加入1.7份丁苯橡胶乳液，搅拌分散均匀，均匀涂覆在负极集流体表面，烘干 待用；
将涂覆后的正负极片进行分切、冲片，然后正极极片和负极极片通过隔膜隔开，采用铝塑膜封装，注入自制电解液，充分浸润，化成分容，制得锂离子电池。
性能测试
将实施例3、6以及对比例1所制备的锂离子电池进行如下性能测试条件：
(1)高温存储性能测试：将电池置于60℃环境下，存储30天、60天、90天，然后1/3C放电，再1/3C进行3次充放电，计算最后一次放电容量与初始容量比值，得到容量恢复率。
(2)倍率测试：在25℃环境下，将电池以0.333C电流恒流恒压充至满电，然后分别以0.333C、1C、2C、3C电流放电。
(3)循环性能测试条件：电池在45℃温度下，以1C/1C充放电循环至容量到达初始容量80％时所循环的圈数。
图1为本发明实施例3所得复合正极的SEM图。
图2和图3为实施例3和6以及对比例1所制备电池高温存储容量恢复率和DCR增长曲线，实施例6展现最佳高温存储性能，其高温存储90d后，容量恢复率高达97.67％,DCR增长仅3.22％，实施例3展现良好的高温存储性能，其90d容量恢复率为93.95％，DCR增长为7.89，而对比例90d高温存储性能明显差于实施例3和6，其容量恢复率仅为86.33％，DCR增长高达10.38％，表明正极材料的包覆及加入无机固态电解质后对高温存储有显著改善，正极材料的包覆可以阻挡电解液与正极直接接触，减少活性锂损失，防止界面过度增长，而无机固态电解质本身具有良好的热稳定性，在正极中可以提高电解液浸润性，降低阻抗，从而改善高温存储性能。
图4为实施例3和6以及对比例1所制备电池倍率放电图，从图中可以发现，实施例6展现了更加优异的倍率性能，尤其在3C倍率放电时，其容量保持率可高达94.23％，实施例3倍率放电与实施例表现相当，其3C放电容量保持率达到92.08％，而对比例1从1C至3C放电，其容量保持率明显低于实施例3和6，仅有73.25％，这是由于实施例3和6中加入了无机固态电解质，提高了锂离子迁移速率，从而提高电池倍率放电性能。
图5为实施例3和6以及对比例1高温循环曲线，从图中可以发现，实施例6展现优异的高温循环性能，其容量达到初始容量80％时，循环圈数高达1100圈，实施例3为852圈，对比例仅有752圈，这是由于实施例6正极进行了包覆，缓解金属离子溶解于电解液中，沉积在负极表面，从而提高高温循环性能，此外无机固态电解质的加入进一步提高离离子迁移速率及热稳定性，进一步改善高温性能。
本发明中所用原料、设备，若无特别说明，均为本领域的常用原料、设备；本发明中所用方法，若无特别说明，均为本领域的常规方法。
以上所述，仅是本发明的较佳实施例，并非对本发明作任何限制，凡是根据本发明技术实质对以上实施例所作的任何简单修改、变更以及等效变换，均仍属于本发明技术方案的保护范围。

Claims (10)

  1. 一种含固态电解质的高镍三元复合正极，包括正极集流体、设有所述正极集流体上的正极材料层，其特征在于：所述正极材料层由含有正极活性物质、无机固态电解质、导电剂和粘结剂的正极浆料固化而成；
    所述正极活性物质为表面包覆有包覆层的高镍镍钴锰LiNi xCo yMn zO 2或高镍镍钴铝LiNi xCo yAl zO 2中的一种或多种，其中0.6≤x＜1.0，0＜y＜0.2，x+y+z＝1；所述包覆层中含有Li 2+XC 1-XB XO 3，其中0<X<1；
    所述的无机固态电解质选自Li 7La 3Zr 2O 12、Li 10GeP 2S 12、Li 2O-Al 2O 3-SiO 2-P 2O 5-TiO 2-GeO 2、Li 2O-Al 2O 3-SiO 2-P 2O 5-TiO 2、Li 6.75La 3Zr 1.75Ta 0.25O 12、Li 9.54Si 1.74P 1.44S 11.7Cl 0.3、Li 2S-P 2S 5、Li 2O-P 2O 5、Li 3.5V 0.5Ge 0.5O 4和Li 14ZnGe 4O 16中的一种或多种。
  2. 如权利要求1所述的高镍三元复合正极，其特征在于，所述正极活性物质、无机固态电解质、导电剂、粘结剂的干粉重量比为90-98:0.1-5:1-3:1-2。
  3. 如权利要求1所述的高镍三元复合正极，其特征在于，所述无机固态电解质的粒径小于1μm。
  4. 如权利要求1所述的高镍三元复合正极，其特征在于，所述包覆层中还包括其他包覆材料，选自氧化铝，氧化镁，氧化硼和氧化钨中的一种或几种。
  5. 如权利要求4所述的高镍三元复合正极，其特征在于，正极活性物质的制备方法包括如下步骤：
    (1)将高镍镍钴锰或高镍镍钴铝的前驱体混合，搅拌均匀得到粉末材料，将粉末材料进行一次煅烧，粉碎后得到一次煅烧样品粉末；
    (2)将一次煅烧样品粉末分散到碱液中，搅拌使其充分润湿，抽滤后真空干燥，再进行二次煅烧，得到二次煅烧样品粉末；
    (3)将硼酸锂与碳酸锂按B原子和C原子的摩尔比混合均匀后烧结，制得Li 2+XC 1-XB XO 3；
    (4)将二次煅烧样品粉末与Li 2+XC 1-XB XO 3以及其他包覆材料混合均匀后进行三次煅烧，得到表面包覆有含Li 2+XC 1-XB XO 3的包覆层的高镍镍钴锰或高镍镍钴铝。
  6. 如权利要求5所述的高镍三元复合正极，其特征在于，
    步骤(1)中，一次煅烧温度为700～900℃，煅烧时间18～26h；
    步骤(2)中，所述碱液选自氢氧化锂溶液、碳酸锂溶液和硝酸锂溶液中的一种或几种，所述碱液的浓度为0.1～5mol/L；搅拌时间0.5～5h，真空干燥温度100～300℃，干燥时间10～24h；二次煅烧的环境为空气和/或CO 2气氛，二次煅烧温度为200～500℃，煅烧时间2～5h；
    步骤(3)中，烧结温度800～900℃，烧结时间18～26h。
  7. 如权利要求6所述的高镍三元复合正极，其特征在于，步骤(4)中，Li 2+xC 1-xB xO 3的质量为二次煅烧样品粉末质量的500～5000ppm；其他包覆材料的添加量为二次煅烧样品粉末质量的400～20000ppm；三次煅烧温度为600～800℃，煅烧时间18～26h。
  8. 如权利要求1所述的高镍三元复合正极，其特征在于，所述导电剂选自石墨烯、碳纳米管、导电碳纤维、导电炭黑、导电石墨和乙炔黑中的至少一种。
  9. 如权利要求1所述的高镍三元复合正极，其特征在于，所述粘结剂选自聚偏氟乙烯、聚酰亚胺和聚丙腈中的一种或多种。
  10. 一种含有如权利要求1～9之一所述高镍三元复合正极的锂离子电池。
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