Ternary positive electrode material of lithium ion battery, preparation method of ternary positive electrode material, lithium ion battery and electric device

Abstract

The invention discloses a lithium ion battery ternary positive electrode material, which comprises a ternary positive electrode material matrix and a composite coating layer coated on the surface of the matrix, and the composite coating layer is mainly composed of LiCoO2 and perovskite minerals. The preparation method comprises the following steps: mixing a ternary positive electrode material hydroxide precursor, a lithium source and an M source, and sintering to obtain a matrix; and mixing the matrix with a lanthanum source, a calcium source and a cobalt source, and sintering to obtain the ternary positive electrode material of the lithium ion battery. The invention also discloses a lithium ion battery and an electric device. According to the invention, the surface of the ternary positive electrode material substrate is coated with the composite coating layer composed of LiCoO2 and LaeCa1-eCoO3-f, and LiCoO2 is tightly and stably coated on the surface of the substrate, so that the problem of performance deterioration caused by shedding of the coating layer is prevented; the LaeCa1-eCoO3-f is dispersed around the LiCoO2, so that the stability of the LiCoO2 is enhanced, and the high-temperature electrical property of the ternary positive electrode material is effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion batteries, and particularly relates to a ternary cathode material for lithium-ion batteries and its preparation method, as well as lithium-ion batteries and electrical devices. Background Technology

[0002] In recent years, China's new energy market has shown remarkable rapid growth. Ternary cathode materials, with their unique advantages, occupy an important position in the new energy industry chain. With the continuous growth of market demand, the technology of ternary cathode materials has also developed rapidly. Currently, a Co-coating technology is being widely used in the modification process of ternary cathode materials. This technology successfully forms a lithium-deficient LiCoO2 coating layer on the surface of the ternary cathode material by mixing and sintering the ternary cathode material with Co at high temperature. This coating layer can effectively improve the kinetic performance of the ternary cathode material, thereby significantly improving the material capacity and DCR.

[0003] Although cobalt coating technology has achieved significant technical results, it still has certain technical drawbacks. Specifically, lithium-deficient LCO tends to be in a metastable state under high-temperature operating conditions. In this state, it is very prone to decomposition reactions, generating rock salt phase Co3O4, accompanied by the production of O2. This not only leads to a significant increase in the battery's internal resistance but may also cause gas expansion risks, threatening battery safety. Furthermore, the generated O2 may further react with the electrolyte, further deteriorating battery performance and reducing its lifespan. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a ternary cathode material for lithium-ion batteries, a method for preparing the same, a lithium-ion battery, and an electrical device.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0006] A ternary cathode material for lithium-ion batteries includes a ternary cathode material matrix and a composite coating layer wrapped around the surface of the ternary cathode material matrix. The composite coating layer is mainly composed of LiCoO2 and perovskite minerals.

[0007] Preferably, in the aforementioned ternary cathode material for lithium-ion batteries, the perovskite is an ABO3-type perovskite oxide with oxygen vacancies.

[0008] In the aforementioned ternary cathode material for lithium-ion batteries, preferably, the perovskite mineral has the chemical formula La. e Ca 1- e CoO 3-f, 0 < e < 1, 0 < f ≤ 0.5.

[0009] In the aforementioned ternary cathode material for lithium-ion batteries, preferably, the mass fraction of La relative to the ternary cathode material matrix in the composite coating layer is 350–2000 ppm, the mass fraction of Ca relative to the ternary cathode material matrix is ​​200–1000 ppm, and the mass fraction of Co relative to the ternary cathode material matrix is ​​3500–35000 ppm.

[0010] Preferably, in the aforementioned ternary cathode material for lithium-ion batteries, the kinetic strength coefficient K of the ternary cathode material is given by: K = Δσ - [-0.0005(x+y) + 0.001|xy|], where x is the mass fraction of La relative to the ternary cathode material matrix, y is the mass fraction of Ca relative to the ternary cathode material matrix (expressed in ppm), and Δσ is the difference between the electronic conductivity of the ternary cathode material and the electronic conductivity of the ternary cathode material matrix. The kinetic strength coefficient K is closely related to the kinetic performance of the ternary cathode material; a larger K value indicates better material kinetic performance and lower resistance in electrical performance tests.

[0011] The aforementioned ternary cathode material for lithium-ion batteries, preferably, has been found through research that when 350≤x≤2000, 200≤y≤1000, and 0≤|xy|≤1000, the ternary cathode material has excellent short-term and long-term electrical properties, especially with significantly improved high-temperature electrical properties.

[0012] The applicant of this invention discovered through research that the content of La and Ca are key factors affecting the kinetic strength coefficient of ternary cathode materials. When La and Ca are not added, i.e., only a cobalt source is added during the second sintering to form LCO coating, the electronic conductivity of the ternary cathode material decreases significantly, where -4 ≤ K < -1.3. When the amount of La and Ca added is small, trace amounts of La are formed on the surface of the ternary cathode material. e Ca 1-e CoO 3-f For perovskite oxides, the K value increases slightly, where -1.3 ≤ K < -0.5; however, due to the small quantity of perovskite oxides, it is difficult to achieve a significant improvement in long-term high-temperature performance. When 350 ≤ x ≤ 2000, 200 ≤ y ≤ 1000, and 0 ≤ |xy| ≤ 1000, the K value of the ternary cathode material is -0.5 ≤ K ≤ 0.5. At this point, the addition amounts of La and Ca are appropriate, which helps to form a suitable amount of La on the surface of the ternary cathode material. e Ca 1-e CoO 3-fPerovskite oxides improve electronic conductivity and long-term stability, thus exhibiting excellent short-term and long-term electrical properties. When the amounts of La and Ca added are excessive, a larger quantity of La is formed. e Ca 1-e CoO 3-f Perovskite oxides improve the long-term performance of materials, but the presence of significant amounts of La and Ca oxides negatively impacts short-term electrical performance, resulting in a decrease in the K value (-4 ≤ K < -0.5). When the amounts of La and Ca are appropriate, but the difference in their content is too large, an excess of La or Ca can occur in localized areas on the material surface. This excess La or Ca will also exist as oxides after high-temperature sintering, further detrimental to short-term electrical performance (-4 ≤ K < -0.5). Therefore, by controlling the amount of La and Ca added and the difference in their content, the kinetic coefficient K of the ternary cathode material can be controlled, thereby enabling the ternary cathode material to possess excellent short-term and long-term electrical performance simultaneously.

[0013] Preferably, in the aforementioned ternary cathode material for lithium-ion batteries, the chemical formula of the ternary cathode material matrix is ​​Li. 1+a Ni b Co c Mn 1-b-c-d M d O z Wherein, 0≤a≤0.2, 0.6≤b≤0.95, 0.05≤c≤0.2, 0<d≤0.1, 0.05≤1-bcd≤0.3, 1.8<z<2.2, and M is a doping element selected from at least one of F, Zr, Al, Ti, W, Ba, Y, Sb, Sr, and Nb.

[0014] Preferably, the ternary cathode material for lithium-ion batteries described above has a median particle size D50 of 2 μm-5 μm and a specific surface area of ​​0.4-1.1 m². 2 / g; the thickness of the coating layer is 0.02μm-0.2μm.

[0015] As a general inventive concept, the present invention also provides a method for preparing the above-mentioned ternary cathode material for lithium-ion batteries, comprising the following steps:

[0016] (1) Mix the ternary cathode material hydroxide precursor, lithium source and M source, and then sinter to obtain the ternary cathode material matrix;

[0017] (2) The ternary cathode material matrix is ​​mixed with lanthanum source, calcium source and cobalt source, and then sintered to obtain the lithium-ion battery ternary cathode material.

[0018] In the above preparation method, preferably, in step (1), the sintering is carried out in an oxygen atmosphere with a concentration of not less than 95%, the sintering temperature is 650-1000℃, and the sintering time is 8-16h.

[0019] In the above preparation method, preferably, in step (1), the amount of M source added is calculated based on the dopant element M, and the mass fraction of the dopant element M relative to the ternary cathode material hydroxide precursor is 2000-7000 ppm.

[0020] In the above preparation method, preferably, in step (2), the sintering is carried out in an oxygen atmosphere with a concentration of 40-80%, the sintering temperature is 600-900℃, and the sintering time is 4-12h. During high-temperature sintering, most of the La and Ca will react with Co to form La. e Ca 1-e CoO 3-f Perovskite oxides, thereby improving electronic conductivity.

[0021] In the above preparation method, preferably, in step (2), the amount of cobalt source added is calculated as cobalt element, and the mass fraction of cobalt element relative to the ternary cathode material matrix is ​​3500-35000 ppm.

[0022] In the above preparation method, preferably, the lithium source is selected from at least one of lithium hydroxide, lithium carbonate, lithium fluoride, and lithium acetate;

[0023] The M source is selected from at least one of oxides, hydroxides, sulfates, nitrates, acetates, and carbonates containing the M element;

[0024] The lanthanum source is selected from at least one of lanthanum oxide, lanthanum chloride, lanthanum hydroxide, lanthanum carbonate, and lanthanum nitrate.

[0025] The calcium source is selected from at least one of calcium oxide, calcium chloride, calcium hydroxide, calcium carbonate, and calcium nitrate.

[0026] The cobalt source is selected from at least one of cobalt hydroxide, cobalt hydroxyoxide, cobalt oxide, cobalt sulfate, and cobalt acetate.

[0027] As a general inventive concept, the present invention also provides a lithium-ion battery, comprising the above-described ternary cathode material for lithium-ion batteries or the ternary cathode material for lithium-ion batteries prepared by the above-described preparation method.

[0028] As a general inventive concept, the present invention also provides an electrical device including the aforementioned lithium-ion battery.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) The present invention coats the surface of a ternary cathode material matrix with LiCoO2 and La having oxygen vacancies. e Ca 1-e CoO 3-f In the composite coating layer, LiCoO2 serves as the main structural component, exhibiting excellent lattice matching and chemical compatibility with the ternary cathode material. This allows the coating layer to tightly and stably adhere to the surface of the ternary cathode material substrate, preventing performance degradation caused by coating layer detachment. The highly reactive LiCoO2 is prone to decomposition reactions that generate oxygen under high-temperature operating conditions, while the relatively small amount of La... e Ca 1-e CoO 3-f Dispersed around LiCoO2, La e Ca 1-e CoO 3-f As an oxygen reduction electrocatalyst, it can suppress the oxygen release reaction of LiCoO2, thereby enhancing the stability of LiCoO2 and ultimately effectively improving the high-temperature electrical performance of ternary cathode materials.

[0031] (2) This invention will use La with oxygen vacancies e Ca 1-e CoO 3-f Perovskite oxide coatings on the surface of ternary cathode materials can capture and store oxygen released from the material's interior during long-term cycling, and then return it during subsequent charge-discharge cycles. This suppresses harmful phase transitions within the material, reduces oxygen evolution, and improves the material's structural stability. La e Ca 1-e CoO 3-f As a cobalt-based perovskite material, it possesses high oxygen exchange kinetics and oxygen diffusion coefficient, thereby further enhancing the rate of the aforementioned O capture and storage process. It can effectively confine active O within the coating layer without causing side reactions with the electrolyte; furthermore, La... e Ca 1-e CoO 3-f The perovskite oxide coating also serves as a physical barrier between the ternary cathode material and the electrolyte, preventing direct contact between the electrolyte and the cathode material, thereby reducing the potential risk of chemical reactions and further improving the stability of the material.

[0032] (3) The coating layer of the present invention contains La e Ca 1-e CoO 3-f Perovskite oxide, La e Ca 1-e CoO 3-fPerovskite oxides possess high electronic and ionic conductivity, thereby improving the transport rate of electrons and lithium ions during the charge-discharge reaction process. This significantly enhances the kinetic performance of the cathode material, resulting in higher capacity and lower internal resistance.

[0033] (4) This invention modulates the La coating layer of the ternary cathode material. e Ca 1-e CoO 3-f The content of La and Ca in perovskite oxides can be used to regulate the kinetic coefficient K of ternary cathode materials, thereby enabling ternary cathode materials to possess excellent short-term and long-term electrical performance. Attached Figure Description

[0034] Figure 1 This is a scanning electron microscope image of the ternary cathode material prepared in Example 2 of the present invention.

[0035] Figure 2 The image shows the XRD pattern of the ternary cathode material prepared in Example 2 of this invention.

[0036] Figure 3 The discharge curves of the ternary cathode materials prepared in Example 2 and Comparative Example 1 of this invention are shown.

[0037] Figure 4 The above are comparison diagrams of the DCR of the ternary cathode materials prepared in Example 2 and Comparative Example 1 of this invention under different SOCs.

[0038] Figure 5 This is a high-temperature cycling curve of the ternary cathode material prepared in Example 2 and Comparative Example 1 of the present invention.

[0039] Figure 6 This is a diagram showing the storage capacity of the pouch cell prepared with the ternary cathode material in Example 2 and Comparative Example 1 of the present invention.

[0040] Figure 7 This is a high-temperature gas generation diagram of a soft-pack battery using ternary cathode materials prepared in Example 2 and Comparative Example 1 of the present invention. Detailed Implementation

[0041] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0042] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0043] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0044] The electronic conductivity of the materials involved in the following examples and comparative examples was tested under conditions of 25°C, 20kN, and 64MPa. The unit of electronic conductivity is S / m.

[0045] Example 1:

[0046] A ternary cathode material for lithium-ion batteries according to the present invention includes a ternary cathode material matrix Li. 1.03 Ni 0.77 Co 0.0 5Mn 0.18 Zr 0.003 Y 0.002 O2 and a composite coating layer encapsulating the surface of the ternary cathode material substrate. The composite coating layer is mainly composed of LiCoO2 and perovskite minerals, the chemical formula of which is La. 0.3 Ca 0.7 CoO 2.6 The mass fraction of La relative to the ternary cathode material matrix in the composite coating layer is 350 ppm; the mass fraction of Ca relative to the ternary cathode material matrix is ​​200 ppm; the kinetic strength coefficient K of the ternary cathode material is -0.38; the median particle size D50 of the ternary cathode material is 3.6 μm, and the specific surface area is 0.65 m². 2 / g; the coating thickness is 0.05μm.

[0047] The preparation method of the ternary cathode material for lithium-ion batteries in this embodiment includes the following steps:

[0048] (1) Preparation of element-doped ternary cathode material matrix: Ni hydroxide precursor 0.77 Co 0.05 Mn 0.18(OH)2, lithium source LiOH·H2O, and dopant sources ZrO2 and Y2O3 were simultaneously added to a high-speed mixer. The mixing speed was set to 1000 r / min, and the mixing time was 30 min to achieve uniform mixing. The molar ratio of Li to transition metal (Li / Me) was 1.03, and the mass fractions of Zr and Y elements in ZrO2 and Y2O3 relative to the hydroxide precursors were 3000 ppm and 2000 ppm, respectively. The mixed material was then placed in a sintering furnace, which maintained an oxygen atmosphere with an oxygen concentration of 98%. The furnace temperature was increased from room temperature to 905℃ at a rate of 3℃ / min, and sintered at this temperature for 12 h. After sintering, the material was cooled, pulverized, and sieved to obtain a Zr and Y doped ternary cathode material matrix.

[0049] (2) Preparation of perovskite-coated ternary cathode material: Co(OH)2, La2O3, and CaCO3, which serve as coating sources, are mixed with the ternary cathode material matrix obtained in step (1) using a high-speed mixer. The mixing speed is set to 1000 r / min and the mixing time is 30 min. The mass fractions of Co, La, and Ca elements in Co(OH)2, La2O3, and CaCO3 relative to the ternary cathode material matrix are 14000 ppm, 350 ppm, and 200 ppm, respectively. The mixed material is then placed in a sintering furnace. An oxygen atmosphere is maintained in the furnace, with an oxygen concentration of 60%. The furnace temperature is increased from room temperature to 790℃ at a rate of 3℃ / min. The material is sintered at this sintering temperature for 8 h. After the material cools, it is crushed and sieved to obtain the lithium-ion battery ternary cathode material.

[0050] Examples 2-6:

[0051] The preparation methods of Examples 2-6 differ from those of Example 1 only in the amount of La and Ca added, as shown in Table 1. Other preparation processes and parameters remain the same as those of Example 1.

[0052] Comparative Example 1:

[0053] The only difference between the preparation method of Comparative Example 1 and Example 1 is that La2O3 and CaCO3 are not added in step (2), while the other preparation processes and parameters are the same as those of Example 1.

[0054] Comparative Example 2:

[0055] The lithium-ion battery ternary cathode material of this comparative example includes a ternary cathode material matrix and a perovskite mineral layer and a LiCoO2 layer sequentially wrapped on the surface of the ternary cathode material matrix. The difference between the preparation method of the lithium-ion battery ternary cathode material of this comparative example and Example 2 is that in step (2), La2O3 and CaCO3 are added first and sintered at 790°C for 8 hours. After the sintered product is crushed and sieved, Co(OH)2 is added and sintered at 790°C for 8 hours. Other preparation processes and parameters are the same as those in Example 2.

[0056] Comparative Example 3:

[0057] The lithium-ion battery ternary cathode material of this comparative example includes a ternary cathode material matrix and a LiCoO2 layer and a perovskite layer sequentially coated on the surface of the ternary cathode material matrix. The preparation method of the lithium-ion battery ternary cathode material of this comparative example differs from that of Comparative Example 2 only in step (2), where Co(OH)2 is added first and sintered at 790°C for 8 hours, followed by the addition of La2O3 and CaCO3 and sintering at 790°C for 8 hours; other preparation processes and parameters remain the same as those of Comparative Example 2.

[0058] The ternary cathode material prepared in Example 2 was tested using FEI-SEM (Field Emission Scanning Electron Microscopy), and the results are shown in the figure. Figure 1 As shown, from Figure 1 The high-temperature Co coating technology exhibits a wrinkled morphology, and the material particles show good dispersion with no obvious agglomeration. Malvern 3000 testing shows the median particle size (D50) of this ternary cathode material to be approximately 3.7 μm, and a specific surface area analyzer shows the specific surface area to be approximately 0.68 m². 2 / g.

[0059] The ternary cathode material prepared in Example 2 was tested using XRD (X-ray diffraction) technology, and the results are shown in [Figure 2]. Figure 2 As shown, from Figure 2 It can be observed that this ternary cathode material has a typical ternary material structure, and its characteristic peak I... (003) / I (104) The ratio of 2.22 indicates that the ternary cathode material has excellent crystallinity and maintains an excellent layered structure.

[0060] The ternary cathode materials prepared in the above examples and comparative examples were used as cathode materials for CR2032 coin cells for performance evaluation and comparison. The results are shown in Table 1. The negative electrode of the coin cells was uniformly lithium-ion, and the separator and electrolyte were purchased commercially. The charge / discharge voltage range of the coin cells was 3.0–4.45V. Specific capacity testing: charge / discharge rate was 0.1C, test temperature was 25℃. DCR testing: the battery was discharged at a rate of 0.2C to a specific SOC, followed by a 30s 1C discharge. The DCR value was calculated by dividing the voltage decay value by the current value during this time, test temperature was 25℃. High-temperature cycling testing: charge / discharge rate was 1C, number of cycles was 50, test temperature was 45℃.

[0061] Table 1 shows the addition amounts of La and Ca in each example and comparative example, as well as the results of material performance testing.

[0062]

[0063]

[0064] As can be seen from the test results in Table 1, adding appropriate amounts of La and Ca in Examples 1-3 resulted in the formation of a suitable amount of La with oxygen vacancies on the surface of the ternary cathode material. e Ca 1-e CoO 3-f Perovskite oxides improve electron conduction and long-term stability. In ternary cathode materials with -0.5 ≤ K ≤ 0.5, the material exhibits excellent discharge capacity, DCR, and high-temperature cycling performance. Examples 4-6 show that excessively low or high La and Ca content, or a large difference between them, during the second sintering process negatively impacts conductivity improvement. The K value remains small, resulting in poor electrical performance, especially high-temperature cycling performance. In Comparative Example 1, no La or Ca was added, leading to a significant decrease in conductivity after the second sintering, a small K value, and relatively poor coin cell performance. In Comparative Examples 2-3, the addition of La and Ca was appropriate, but the two sintering processes resulted in a double-layer coating rather than a composite coating, leading to lower kinetics and stability compared to Example 2, and significantly weaker electrical performance.

[0065] The coin cell performance test results of Example 2 and Comparative Example 1 are used as typical examples for graphical comparison. The results of 0.1C first-cycle discharge, DCR at different SOCs, and high-temperature cycle retention are shown in the graphs. Figure 3-5 middle.

[0066] The ternary cathode materials prepared in Example 2 and Comparative Example 1 were used as cathode materials for lithium-ion batteries, and further fabricated into pouch batteries for high-temperature performance evaluation and comparison. In the fabrication process of the pouch battery, its capacity was set at 1.65 Ah, graphite was selected as the negative electrode, and other materials such as the separator, electrolyte, binder, and conductive agent were all obtained through commercial procurement. A winding process was used to fabricate the pouch battery, followed by a series of processes including electrolyte injection, formation, degassing, and heat sealing, ensuring that the battery fabrication process was standardized and met standards. The high-temperature performance testing conditions for the pouch battery were: test voltage of 2.8-4.45V, test environment of a 60℃ incubator; high-temperature storage was performed using a 1C charge / discharge rate, and the battery capacity was tested at different time points (0 / 2 / 4 / 8 weeks). The capacity recovery rate was obtained by dividing the current capacity by the initial (0-week) capacity and displayed on [the screen / platform]. Figure 6 In the high-temperature gas generation test, a 0.33C charge / discharge rate was used. The gas generation rate was tested at different time points (1 / 2 / 3 / 4 weeks) using the water displacement method. The result was divided by the mass of the corresponding positive electrode material of the pouch cell to obtain the gas generation per unit mass, and this result is presented in [the table / document / etc.]. Figure 7 middle.

[0067] Depend on Figure 6 and Figure 7 As can be seen, compared with Comparative Example 1, the high-temperature storage capacity recovery rate of Example 2 of the present invention is significantly improved, and the high-temperature gas production is significantly reduced. This indicates that the high-temperature electrical performance of the perovskite-coated ternary cathode material provided by the present invention is significantly improved.

[0068] The foregoing has detailed the specific preferred embodiments of the present invention, but this does not imply that the actual application of the present invention is limited to these descriptions. Those skilled in the art can easily perform a series of simple inferences or substitutions without departing from the core principles of the present invention. These derivations and variations based on the principles of the present invention should all be included within the scope of protection of the present invention. Therefore, the application scope of the present invention is not limited to the specific embodiments described herein.

Claims

1. A ternary cathode material for lithium-ion batteries, characterized in that, It includes a ternary cathode material matrix and a composite coating layer wrapped around the surface of the ternary cathode material matrix, wherein the composite coating layer is mainly composed of LiCoO2 and perovskite minerals.

2. The ternary cathode material for lithium-ion batteries as described in claim 1, characterized in that, The perovskite is an ABO3-type perovskite oxide with oxygen vacancies.

3. The ternary cathode material for lithium-ion batteries as described in claim 1, characterized in that, The chemical formula of the perovskite is La. e Ca 1-e CoO 3-f , 0 < e < 1, 0 < f ≤ 0.

5.

4. The ternary cathode material for lithium-ion batteries as described in claim 3, characterized in that, The La element in the composite coating layer has a mass fraction of 350–2000 ppm relative to the ternary cathode material matrix, the Ca element has a mass fraction of 200–1000 ppm relative to the ternary cathode material matrix, and the Co element has a mass fraction of 3500–35000 ppm relative to the ternary cathode material matrix.

5. The ternary cathode material for lithium-ion batteries as described in claim 1, characterized in that, The kinetic strength coefficient of the ternary cathode material is K = Δσ - [-0.0005(x+y) + 0.001|xy|], where x is the mass fraction of La relative to the ternary cathode material matrix, y is the mass fraction of Ca relative to the ternary cathode material matrix, and the mass fraction is expressed in ppm; Δσ is the difference between the electronic conductivity of the ternary cathode material and the electronic conductivity of the ternary cathode material matrix.

6. The ternary cathode material for lithium-ion batteries as described in claim 5, characterized in that, The kinetic strength coefficient K of the ternary cathode material ranges from -0.5 to 0.

5.

7. The ternary cathode material for lithium-ion batteries as described in any one of claims 1 to 6, characterized in that, The chemical formula of the ternary cathode material matrix is ​​Li. 1+a Ni b Co c Mn 1-b-c-d M d O z Wherein, 0≤a≤0.2, 0.6≤b≤0.95, 0.05≤c≤0.2, 0<d≤0.1, 0.05≤1-bcd≤0.3, 1.8<z<2.2, and M is a doping element selected from at least one of F, Zr, Al, Ti, W, Ba, Y, Sb, Sr, and Nb.

8. The ternary cathode material for lithium-ion batteries as described in any one of claims 1 to 6, characterized in that, The median particle size D50 of the ternary cathode material is 2 μm to 5 μm, and the specific surface area is 0.4 to 1.1 m². 2 / g; the thickness of the coating layer is 0.02μm~0.2μm.

9. A method for preparing a ternary cathode material for lithium-ion batteries as described in any one of claims 1 to 8, characterized in that, Includes the following steps: (1) A ternary cathode material hydroxide precursor, a lithium source and an M source are mixed and then sintered to obtain a ternary cathode material matrix; M is selected from at least one of F, Zr, Al, Ti, W, Ba, Y, Sb, Sr and Nb; (2) The ternary cathode material matrix is ​​mixed with lanthanum source, calcium source and cobalt source, and then sintered to obtain the lithium-ion battery ternary cathode material.

10. The preparation method according to claim 9, characterized in that, In step (1), the sintering is carried out in an oxygen atmosphere with a concentration of not less than 95%, the sintering temperature is 650-1000℃, and the sintering time is 8-16h.

11. The preparation method according to claim 9, characterized in that, In step (1), the amount of M source added is calculated based on the dopant element M, and the mass fraction of the dopant element M relative to the ternary cathode material hydroxide precursor is 2000 to 7000 ppm.

12. The preparation method according to claim 9, characterized in that, In step (2), the sintering is carried out in an oxygen atmosphere with a concentration of 40% to 80%, the sintering temperature is 600 to 900°C, and the sintering time is 4 to 12 hours.

13. The preparation method according to claim 9, characterized in that, In step (2), the amount of cobalt source added is calculated as cobalt element, and the amount of cobalt element added is 3500 to 35000 ppm by mass relative to the ternary cathode material matrix; the amount of lanthanum source added is calculated as lanthanum element, and the amount of lanthanum element added is 350 to 2000 ppm by mass relative to the ternary cathode material matrix; the amount of calcium source added is calculated as calcium element, and the amount of calcium element added is 200 to 1000 ppm by mass relative to the ternary cathode material matrix.

14. The preparation method according to claim 9, characterized in that, The lithium source is selected from at least one of lithium hydroxide, lithium carbonate, lithium fluoride, and lithium acetate; The lanthanum source is selected from at least one of lanthanum oxide, lanthanum chloride, lanthanum hydroxide, lanthanum carbonate, and lanthanum nitrate. The calcium source is selected from at least one of calcium oxide, calcium chloride, calcium hydroxide, calcium carbonate, and calcium nitrate. The cobalt source is selected from at least one of cobalt hydroxide, cobalt hydroxyoxide, cobalt oxide, cobalt sulfate, and cobalt acetate.

15. A lithium-ion battery, characterized in that, The lithium-ion battery ternary cathode material includes any one of claims 1 to 8, or the lithium-ion battery ternary cathode material prepared by any one of claims 9 to 14.

16. An electrical appliance, characterized in that, Including the lithium-ion battery as described in claim 15.

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