Modified ternary positive electrode material, preparation method thereof and lithium ion battery

Abstract

The invention provides a modified ternary positive electrode material, a preparation method thereof and a lithium ion battery. The modified ternary positive electrode material comprises a ternary positive electrode material substrate and a coating layer coated on the surface of the ternary positive electrode material substrate, wherein the coating layer comprises a first component and a second component, the first component is a microporous polymer formed by polymerizing tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde, and the second component is high-entropy aluminate. According to the invention, the microporous polymer formed by polymerizing tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde and the high-entropy aluminate are compounded as the material of the coating layer, so that the modified ternary positive electrode material has good energy density and conductivity, and is not easy to thermally decompose; the stability and the safety of the modified ternary positive electrode material can be improved, so that the modified ternary positive electrode material can have better stability and safety in the lithium ion battery.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and in particular to a modified ternary cathode material and a preparation method thereof, and a lithium-ion battery. Background Art

[0002] As the core component of lithium-ion batteries, the performance of cathode materials is directly related to the energy density, cycle stability and overall cost of batteries. x Co γ Mn 1-x-γ O2-type cathode materials (with high Ni content) have become a research hotspot in the lithium battery industry due to their outstanding energy density, long cycle life, and reasonable economics. However, the safety issues of high-nickel ternary materials have become a major bottleneck restricting their widespread application. In particular, as the Ni content increases, the structural stability and thermal safety of the materials decrease significantly, which is directly related to battery safety.

[0003] Thermal management within the battery is crucial for ensuring safety. As temperature increases, the chemical and physical processes within the battery become more complex and unstable. Typically, at around 150°C, the electrolyte begins to decompose, generating gases and increasing internal pressure. Once the separator melts at high temperatures, the battery loses its structural integrity, triggering an internal short circuit and rapidly increasing the temperature. When temperatures exceed 200°C, the cathode material begins to decompose, releasing oxygen. This oxygen release, combined with the oxidation reaction of the organic electrolyte, generates significant heat energy, a process known as thermal runaway, which can result in battery fire or even explosion. Similarly, the thermal stability of the cathode material is a crucial safety indicator for lithium-ion batteries. In high-nickel ternary materials, the high oxidation state of nickel makes it susceptible to decomposition at high temperatures, producing highly oxidizing species. This poses a heightened safety risk to the battery under overheating conditions. Therefore, improving the thermal and structural stability of the cathode material, and thereby enhancing the safety of the entire battery, has become a key issue currently under investigation in lithium-ion battery research.

[0004] With the widespread use of high-nickel ternary materials in lithium-ion batteries, their thermal stability and safety issues have become increasingly prominent, becoming key factors limiting battery stability and safety. Currently, methods used to improve the safety of ternary cathode materials mainly include surface coating, material modification, and electrolyte additives. However, these methods often have disadvantages such as high cost, complex processes, and impact on the performance of the original materials, which limits their application in large-scale battery production.

[0005] Therefore, finding a modification method for ternary positive electrode materials that can effectively improve the thermal stability of ternary materials, especially the structural stability and safety of high-nickel ternary materials with a high Ni content, without significantly increasing the cost and complexity is of great significance for promoting the further development of lithium-ion battery technology. Summary of the Invention

[0006] The main purpose of the present invention is to provide a modified ternary positive electrode material and its preparation method, and a lithium-ion battery, so as to solve the problems of structural instability and poor safety caused by the high Ni content in high-nickel ternary materials in the prior art, as well as the problems of complex and high-cost modification processes for ternary positive electrode materials in the prior art, which make it difficult to achieve large-scale production and application. The purpose is to further improve the electrochemical performance, thermal stability and safety of lithium-ion battery positive electrode materials.

[0007] The present invention provides a modified ternary positive electrode material, which includes a ternary positive electrode material substrate and a coating layer coated on the surface of the ternary positive electrode material substrate; wherein the coating layer includes a first component and a second component, the first component is a microporous polymer formed by polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde, and the second component is a high entropy aluminate.

[0008] Furthermore, the weight ratio of the ternary positive electrode material substrate and the coating layer is 100:(0.01-2); and / or the weight ratio of the first component and the second component in the coating layer is (0.1-10):1.

[0009] Furthermore, the weight ratio of the ternary positive electrode material substrate and the coating layer is 100:(0.1-1); and / or the weight ratio of the first component and the second component in the coating layer is (1-5):1.

[0010] Furthermore, when tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde are polymerized to form a microporous polymer, the polymerization temperature is 120-180° C.; the polymerization time is 2-5 days; and / or, when tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde are polymerized to form a microporous polymer, the molar ratio of tetraamino copper phthalocyanine to biphenyl dicarboxaldehyde is 1:(2-4); and / or, the pore size of the microporous polymer is 2-50 nm; and / or, the high entropy aluminate is obtained by sintering aluminum oxide and at least five rare earth oxides; preferably, the rare earth oxide is At least five of lanthanum oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, scandium oxide and yttrium oxide; and / or the rare earth oxides are ytterbium oxide, yttrium oxide, europium oxide, lutetium oxide and erbium oxide; and / or the sintering temperature is 1200-1800°C and the time is 8-15 hours; and / or the molar amounts of the rare earth elements in the high entropy aluminate are equal, and the ratio of the sum of the molar amounts of aluminum and the rare earth elements is (2-4):5.

[0011] Furthermore, the chemical formula of the ternary cathode material substrate is LiNi x Co y Mn (1-x-y) O2, wherein 0.5≤x<1.0, 0<y≤0.2, and x+y<1; the particle size of the ternary positive electrode material substrate is 2.5μm≤D50≤12μm.

[0012] According to another aspect of the present invention, a preparation method for the above-mentioned modified ternary positive electrode material is also provided, which comprises the following steps: dissolving tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde in a first organic solvent, carrying out a polymerization reaction in an inert gas atmosphere to obtain a reaction mixture; subjecting the reaction mixture to centrifugation, washing and a first drying to obtain a microporous polymer; subjecting aluminum oxide and at least five rare earth oxides to a first ball milling mixing in a second organic solvent to obtain a mixed slurry; separating the mixed slurry, subjecting the obtained solid component to a second drying, and then depositing it by electron beam evaporation to form a high-entropy aluminate film; sintering, crushing and sieving the high-entropy aluminate film in sequence to obtain a high-entropy aluminate; subjecting the microporous polymer and the high-entropy aluminate to a second ball milling mixing to obtain a mixed material; and coating the mixed material on the surface of the ternary positive electrode material substrate by plasma spraying to obtain a modified ternary positive electrode material.

[0013] Furthermore, the molar ratio of tetraaminocopper phthalocyanine to biphenyldicarboxaldehyde is 1:(2-4); and / or the polymerization reaction temperature is 120-180°C, and the polymerization reaction time is 2-5 days; and / or the number of washings is 3-5 times, and the washing solvent is N'N-dimethylformamide; and / or the first organic solvent is one or more of N'N-dimethylacetamide, N'N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone; and / or the first drying temperature is 60-110°C, and the first drying time is 20-30h; and / or the concentration of the mixed solution obtained after dissolving tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde in the first organic solvent is 0.01-0.1g / mL.

[0014] Furthermore, the rare earth oxide is at least five of lanthanum oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, scandium oxide and yttrium oxide; and / or, the rare earth oxide is ytterbium oxide, yttrium oxide, europium oxide, lutetium oxide and erbium oxide.

[0015] Furthermore, the second drying temperature is 60-80°C, and the second drying time is 5-12h; and / or, the electron beam voltage is 1-3kV, the electron beam current is 3-5A, and the deposition time is 3-20min; and / or, the thickness of the high-entropy aluminate film is 20-200nm; and / or, the second organic solvent is ethanol; and / or, the particle size of the high-entropy aluminate is 30-150nm; and / or, the sintering temperature is 1200-1800°C, and the sintering time is 8-15h; and / or, the second ball milling process includes mixing the microporous polymer and high-entropy aluminate with ethanol and grinding balls, and then performing a second ball milling mixing operation; preferably, the weight ratio of the microporous polymer and high-entropy aluminate to ethanol and grinding balls is (0.1-1):(0.1-1):(3-5):(3-5).

[0016] Furthermore, the parameters of the plasma spraying process are: main gas: Ar, auxiliary gas: H2, carrier gas: N2, spraying distance is 70-120 mm, spraying power is 30-50 kW, and spraying thickness is 20-200 nm; and / or, the parameters of the deposition process using electron beam evaporation are: electron beam voltage is 1-3 kV, current is 3-5 A, and deposition time is 3-20 min.

[0017] According to the third aspect of the present invention, a lithium-ion battery is further provided, which includes the above-mentioned modified ternary positive electrode material; or, the lithium-ion battery includes the modified ternary positive electrode material prepared by the preparation method of the above-mentioned modified ternary positive electrode material.

[0018] The present invention provides a modified ternary positive electrode material, comprising a ternary positive electrode material substrate and a coating layer coated on the surface of the ternary positive electrode material substrate; wherein the coating layer comprises a first component and a second component, the first component being a microporous polymer formed by polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde, and the second component being a high-entropy aluminate. The present invention uses a composite of a microporous polymer formed by polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde and a high-entropy aluminate as the coating layer of the ternary positive electrode material substrate. While fully leveraging the respective advantages of the two components, the synergistic effect of the two components enables the modified ternary positive electrode material to have good energy density and electrical conductivity while being less susceptible to thermal decomposition and thermal runaway, thereby improving the stability and safety of the modified ternary positive electrode material, thereby enabling the modified ternary positive electrode material to have better stability and safety in lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0020] Figure 1The figure shows the discharge capacity change curve of the button-type battery prepared by using the modified ternary positive electrode materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention as the positive electrode active material after 50 cycles;

[0021] Figure 2 The DSC curves of the modified ternary cathode materials in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention are shown. DETAILED DESCRIPTION

[0022] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] As mentioned in the background technology section, high-nickel ternary materials have become a research hotspot in the lithium battery industry due to their outstanding energy density, long cycle life and reasonable economy. However, the stability and safety issues of high-nickel ternary materials have become the main bottleneck restricting their widespread application. In particular, with the increase of Ni content, the structural stability and thermal safety of the materials decrease significantly. In severe cases, it may even lead to thermal runaway, causing fire and explosion of the battery. How to improve the thermal stability and structural stability of ternary positive electrode materials and enhance the overall safety performance of the battery has become a key issue that needs to be solved in the current lithium-ion battery research field.

[0024] In order to solve the above problems, the present invention provides a modified ternary positive electrode material, which includes a ternary positive electrode material substrate and a coating layer coated on the surface of the ternary positive electrode material substrate; wherein, the coating layer includes a first component and a second component, the first component is a microporous polymer formed by polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde, and the second component is a high entropy aluminate.

[0025] The modified ternary positive electrode material provided by the present invention includes a ternary positive electrode material substrate and a coating layer applied to the surface of the ternary positive electrode material substrate; wherein the coating layer on the surface of the ternary positive electrode material substrate comprises: a microporous polymer formed by polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde, and a high-entropy aluminate. The present invention achieves the purpose of modifying the ternary positive electrode material by applying a coating layer comprising the above two components to the surface of the ternary positive electrode material substrate. The modified ternary positive electrode material has high thermal stability and structural stability while also having excellent electrochemical properties. The modified ternary positive electrode material is less susceptible to thermal decomposition during use, thereby improving the safety performance of lithium-ion batteries while also having good battery capacity and cycle stability.

[0026] In particular, the coating layer of the modified ternary positive electrode material provided by the present invention includes a first component and a second component, the first component is a microporous polymer formed by the polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde, and the second component is a high entropy aluminate. In the first component of the coating layer, the microporous polymer formed by the polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde not only has the characteristics of microporous structure and large specific surface area, but also can form a stable network structure through the π-π conjugation between molecules in the polymer structure. The above structure can significantly improve the electrochemical performance of the modified ternary positive electrode material. First, the microporous polymer with a conjugated structure can promote the transfer of electrons in the structure, significantly improve the conductivity of the material, and thus optimize the electrochemical reaction process of the battery; second, the rich microporous structure and large specific surface area are beneficial to Li + The efficient intercalation and deintercalation of the microporous polymer is beneficial to the cycle of the lithium-ion battery; thirdly, the bipolar characteristics and pseudocapacitive effect of the microporous polymer help to cause electrochemical reactions at a specific voltage (3.08 / 2.64V), provide additional capacity for the ternary material matrix, enhance the overall energy density of the battery, and benefit the improvement of the electrochemical performance of the lithium-ion battery. In addition, the microporous polymer formed by the polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde also has good thermal stability and chemical stability, and can maintain the integrity of the structure and performance under more harsh conditions, which is beneficial to improving the durability and safety of the battery. Furthermore, the high entropy aluminate in the second component has relatively low thermal conductivity and excellent thermal stability. Using high entropy aluminate as one of the materials for the coating layer of the modified ternary positive electrode material can effectively prevent the thermal decomposition caused by the increase in temperature when the battery is fully charged, thereby avoiding the occurrence of thermal runaway. In addition, the high entropy aluminate also has anti-sintering properties, which helps to maintain the stability of the internal structure of the battery, especially under high temperature conditions, preventing the sintering and performance degradation of the material, and can further improve the safety and cycle life of lithium-ion batteries in high temperature environments.

[0027] The present invention uses a compound of a microporous polymer formed by the polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde and a high-entropy aluminate as one of the raw materials for the coating layer of the ternary positive electrode material, which can give full play to the respective advantages of the above two components. Under the synergistic effect of the two, the modified ternary positive electrode material has good energy density and electrical conductivity while being less prone to heat conduction and heat transfer, which is beneficial to improving the stability and safety of the modified ternary positive electrode material, thereby enabling the modified ternary positive electrode material to have better stability and safety in lithium-ion batteries.

[0028] In summary, the modified ternary cathode material obtained by modifying the ternary cathode material substrate using a microporous polymer linked by tetraaminocopper phthalocyanine and a high-entropy aluminate composite as a coating layer material not only has good energy density and conductivity, but also has improved stability and safety. The coating material used for modification also has the advantage of being inexpensive. The technical solution provided by the present invention comprehensively improves the performance of lithium-ion battery cathode materials in terms of electrochemical performance, thermal stability, and cost control, providing a safer, more efficient, and economical solution for the battery industry.

[0029] In a preferred embodiment, the weight ratio of the ternary positive electrode material substrate and the coating layer is 100:(0.01~2), specifically 100:0.01, 100:0.05, 100:0.1, 100:0.2, 100:0.3, 100:0.4, 100:0.5, 100:0.6, 100:0.7, 100:0.8, 100:0.9, 100:1, 100:1.1, 100:1.2, 100:1.3, 100:1.4, 100:1.5, 100:1.6, 100:1.7, 100:1.8, 100:1.9, 100:2.0, or any weight ratio between any two of the above. By controlling the weight ratio of the ternary positive electrode material substrate and the coating layer in the modified ternary positive electrode material within the above range, the modified ternary positive electrode material can have better energy density and longer cycle life while also having better safety and stability. Preferably, the weight ratio of the ternary positive electrode material substrate to the coating layer is 100:(0.1-1); specifically, for example, 100:0.1, 100:0.15, 100:0.2, 100:0.25, 100:0.3, 100:0.35, 100:0.4, 100:0.45, 100:0.5, 100:0.55, 100:0.6, 100:0.65, 100:0.7, 100:0.75, 100:0.8, 100:0.85, 100:0.9, 100:0.95, 100:1, or any ratio between any two of the above. When the weight ratio of the ternary positive electrode material substrate to the coating layer in the modified ternary positive electrode material is within the above preferred range, the above effect is better.

[0030] Preferably, the weight ratio of the first component to the second component in the coating layer is (0.1-10):1; specifically, for example, 0.1:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1, 10:1, or any weight ratio between any two of the above. Controlling the weight ratio of the first component to the second component in the coating layer within the above range can better utilize the advantages of the microporous polymer and the high entropy aluminate, which is conducive to further improving the stability and safety of the modified ternary cathode material. More preferably, the weight ratio of the first component to the second component in the coating layer is (1-5):1, specifically, for example, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, or any weight ratio between any two of the above. When the weight ratio of the first component to the second component in the coating layer is controlled within the above range, the performance of the modified ternary cathode material is better.

[0031] In a preferred embodiment, when tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde are polymerized to form a microporous polymer, the polymerization temperature is 120-180°C, specifically for example, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, or any temperature between any two of the above; preferably, the polymerization time is 2 to 5 days; preferably, when tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde are polymerized to form a microporous polymer, the molar ratio of tetraaminocopper phthalocyanine to biphenyldicarboxaldehyde is 1:(2-4), specifically for example, 1:2, 1:2.2, 1:2.5, 1:2.8, 1:3, 1:3.2, 1:3.5, 1:3.8, 1:4, or any molar ratio between any two of the above. As mentioned above, in the coating layer, the microporous polymer formed by the polymerization of tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde not only has the characteristics of microporous structure and large specific surface area, but also can form a stable network structure through the π-π conjugation between molecules, which is beneficial to improve the conductivity of the material and promote Li + The microporous polymer prepared under these conditions is used to modify ternary cathode materials, effectively enhancing the efficiency of intercalation and deintercalation, increasing the overall energy density of the battery, and improving the thermal and chemical stability of the material. The microporous polymer prepared under these conditions is used to modify ternary cathode materials, further enhancing the effectiveness of the microporous polymer formed by the polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde. Preferably, the pore size of the microporous polymer is 2 to 50 nm. Controlling the pore size of the microporous polymer within this range improves the performance of the modified ternary cathode material.

[0032] Preferably, the high-entropy aluminate is obtained by sintering aluminum oxide and at least five rare earth oxides; preferably, the sintering temperature is 1200-1800°C and the time is 8-15 hours; specifically, the sintering temperature is 1200°C, 1250°C, 1300°C, 1350°C, 1400°C, 1450°C, 1500°C, 1550°C, 1600°C, 1650°C, 1700°C, 1750°C, 1800°C, or any temperature in between. The high-entropy aluminate prepared under the above conditions is used in the coating layer of the modified ternary cathode material, and the resulting modified ternary cathode material has better performance. Preferably, the molar amounts of each rare earth element in the high-entropy aluminate are equal, and the ratio of the sum of the molar amounts of aluminum and rare earth elements is (2-4):5. Under these ratios, the electrochemical performance, stability, and safety of the modified ternary cathode material can be further improved. Preferably, the rare earth oxides are at least five of lanthanum oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, scandium oxide, and yttrium oxide. Further preferably, the rare earth oxides are ytterbium oxide, yttrium oxide, europium oxide, lutetium oxide, and erbium oxide. Using the above rare earth oxides as components of the high-entropy aluminate improves the overall effect of the modified ternary cathode material. Further preferably, the rare earth oxides are ytterbium oxide, yttrium oxide, europium oxide, lutetium oxide, and erbium oxide. Selecting the above five rare earth oxides as raw materials for the high-entropy aluminate is conducive to further improving the performance of the modified ternary cathode material.

[0033] In a preferred embodiment, the chemical formula of the ternary cathode material substrate is LiNi x Co y Mn (1-x-y) O2, where 0.5 ≤ x < 1.0, 0 < y ≤ 0.2, and x + y < 1; the particle size of the ternary positive electrode material base is 2.5 μm ≤ D50 ≤ 12 μm. Selecting the above-mentioned ternary positive electrode material with a higher nickel content as the base for the modified ternary positive electrode material can improve the performance of the prepared modified ternary positive electrode material. In fact, the advantages of the modification described in the present invention can be further realized by modifying the above-mentioned ternary positive electrode material with a higher nickel content.

[0034] According to another aspect of the present invention, a preparation method for the above-mentioned modified ternary positive electrode material is also provided, which comprises the following steps: dissolving tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde in a first organic solvent, carrying out a polymerization reaction in an inert gas atmosphere to obtain a reaction mixture; subjecting the reaction mixture to centrifugation, washing and a first drying to obtain a microporous polymer; subjecting aluminum oxide and at least five rare earth oxides to a first ball milling mixing in a second organic solvent to obtain a mixed slurry; separating the mixed slurry, subjecting the obtained solid component to a second drying, and then depositing it by electron beam evaporation to form a high-entropy aluminate film; sintering, crushing and sieving the high-entropy aluminate film in sequence to obtain a high-entropy aluminate; subjecting the microporous polymer and the high-entropy aluminate to a second ball milling mixing to obtain a mixed material; and coating the mixed material on the surface of the ternary positive electrode material substrate by plasma spraying to obtain a modified ternary positive electrode material.

[0035] In the above-mentioned preparation method, a microporous polymer is first formed by polymerizing tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde, and then a high-entropy aluminate is prepared using aluminum oxide and rare earth oxides. Finally, the resulting microporous polymer and high-entropy aluminate are thoroughly mixed and then applied to the surface of a ternary cathode material substrate via plasma spraying to obtain a modified ternary cathode material. The above-mentioned preparation method of the modified ternary cathode material is simple to operate and can evenly coat the microporous polymer formed by the polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde and the high-entropy aluminate on the surface of the ternary cathode material substrate, resulting in improved stability and uniformity of the modified ternary cathode material and more stable performance.

[0036] In a preferred embodiment, the molar ratio of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde is 1:(2-4), specifically, for example, 1:2, 1:2.2, 1:2.5, 1:2.8, 1:3, 1:3.2, 1:3.5, 1:3.8, 1:4, or any molar ratio between any two of the above; by controlling the molar ratio of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde within the above range, the obtained microporous polymer can have better conductive properties, which is beneficial to further improve the battery capacity, stability and safety of lithium-ion batteries. Preferably, the polymerization reaction temperature is 120-180°C, specifically, for example, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, or any temperature between any two of the above; the polymerization reaction time is 2-5 days; preferably, the number of washings is 3-5 times, and the washing solvent is N'N-dimethylformamide; preferably, the first organic solvent is one or more of N'N-dimethylacetamide, N'N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone; preferably, the first drying temperature is 60-110°C, and the first drying time is 20-30 hours. Controlling the preparation parameters when preparing the microporous polymer within the above range can make the microporous polymer formed by the polymerization of tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde have better performance, which is beneficial to improving the comprehensive performance of the modified ternary positive electrode material. Preferably, the concentration of the mixed solution obtained by dissolving tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde in the first organic solvent is 0.01 to 0.1 g / mL.

[0037] In a preferred embodiment, the rare earth oxides are at least five of lanthanum oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, scandium oxide, and yttrium oxide. The selection of these rare earth oxides further enhances the stability of the modified ternary cathode material. Further preferably, the rare earth oxides are ytterbium oxide, yttrium oxide, europium oxide, lutetium oxide, and erbium oxide. The selection of these rare earth oxides enhances the stability and safety of the modified ternary cathode material.

[0038] In a preferred embodiment, the second drying temperature is 60-80°C, and the second drying time is 5-12 hours. Preferably, the electron beam voltage is 1-3 kV, the electron beam current is 3-5 A, and the deposition time is 3-20 minutes. Preferably, the thickness of the high-entropy aluminate film is 20-200 nm. Preferably, the second organic solvent is ethanol. Preferably, the particle size of the high-entropy aluminate is 30-150 nm. The sintering temperature is 1200-1800°C, specifically, the sintering temperature is 1200°C, 1250°C, 1300°C, 1350°C, 1400°C, 1450°C, 1500°C, 1550°C, 1600°C, 1650°C, 1700°C, 1750°C, 1800°C, or any temperature in between. The sintering time is 8-15 hours. Controlling the preparation parameters of the high-entropy aluminate in the coating layer within the above ranges improves the stability of the modified ternary cathode material. Preferably, the second ball milling process includes mixing the microporous polymer and high entropy aluminate with ethanol and grinding balls, and then performing a second ball milling mixing operation; preferably, the weight ratio of the microporous polymer and high entropy aluminate to the ethanol and grinding balls is (0.1-1):(0.1-1):(3-5):(3-5). Preferably, the solid content of the mixed slurry is 15-40%; controlling the solid content of the mixed slurry within the above range can achieve better mixing effects.

[0039] In a preferred embodiment, the parameters of the plasma spraying process are: main gas: Ar, auxiliary gas: H2, carrier gas: N2, spraying distance of 70-120 mm, spraying power of 30-50 kW, and spraying thickness of 20-200 nm. Controlling the parameters of the plasma spraying method when applying the microporous polymer and high-entropy aluminate mixture to the surface of the ternary cathode material substrate within the above conditions can enable the microporous polymer and high-entropy aluminate to be more uniformly coated on the surface of the ternary cathode material, which is beneficial to further improve the stability of the ternary cathode material. Preferably, the parameters of the deposition process using electron beam evaporation are: electron beam voltage of 1-3 kV, current of 3-5 A, and deposition time of 3-20 min. Preferably, the spraying thickness is 20-100 nm; controlling the spraying thickness within the above preferred range is more conducive to the transmission of lithium ions.

[0040] According to a third aspect of the present invention, a lithium-ion battery is also provided, comprising the modified ternary cathode material described above; or, comprising the modified ternary cathode material prepared by the method for preparing the modified ternary cathode material described above. Using the modified ternary cathode material provided by the present invention in a lithium-ion battery can result in the resulting lithium-ion battery having not only good energy density and conductivity but also improved stability and safety.

[0041] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0042] Example 1

[0043] S1: 50 mg of tetraamino copper phthalocyanine and 25 mg of biphenyl dicarboxaldehyde are dissolved in 1.5 mL of N'N-dimethylacetamide, placed in a Pyrex reaction tube, and subjected to three cycles of freeze-vacuum-thaw operation. After drying to remove any small amount of water molecules that may be present, the Pyrex reaction tube is heat-sealed to place the system in an inert atmosphere. The heat-sealed Pyrex reaction tube is heated to carry out a polymerization reaction to obtain a reaction mixture, wherein the polymerization reaction temperature is 150°C and the polymerization reaction time is 3 days. After the reaction is completed, the system is naturally cooled to room temperature, the reaction mixture is centrifuged and washed with N'N-dimethylformamide 5 times (at this time, the washing liquid is colorless), and the resulting solid component is dried at 75°C for 24 hours to obtain a microporous polymer formed by the polymerization of tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde.

[0044] S2: Preparation of high entropy aluminate: (Y 0.2 Yb 0.2 Lu 0.2 Eu 0.2 Er 0.2 )3Al5O 12 : Y2O3, Yb2O3, Lu2O3, Eu2O3, Er2O3 and Al2O3 powders are mixed in the molar ratio described in the formula, and ball-milled for 6 hours with anhydrous ethanol as a solvent to obtain a mixed slurry with a solid content of 40%; the solid-liquid slurry is separated, and the obtained solid component is dried at 80°C for 5 hours, sieved through a 300-mesh screen, and then placed in a vacuum deposition chamber as a raw target and deposited by electron beam evaporation to form a high-entropy aluminate film, wherein the parameters of the electron beam evaporation deposition process are: electron beam voltage of 1kV, current of 3A, deposition time of 20min, and the thickness of the obtained high-entropy aluminate film is 200nm. The obtained high-entropy aluminate film is sintered, crushed and sieved in sequence to obtain a high-entropy aluminate (Y 0.2 Yb 0.2 Lu 0.2 Eu 0.2 Er 0.2 )3Al5O 12 ; The sintering temperature is 1500℃, the sintering time is 10h, and the obtained high entropy aluminate particle size is 50nm.

[0045] S3: The microporous polymer prepared above and formed by polymerization of tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde and high entropy aluminate are mixed with ethanol and grinding balls in a weight ratio of 0.5:0.5:4:4 and subjected to ball milling to obtain a mixed material; the mixed material is applied to the surface of the ternary cathode material substrate by plasma spraying to obtain a modified ternary cathode material. The chemical formula of the ternary cathode material substrate is: LiNi 0.7 Co 0.1 Mn 0.2 O2, particle size: D50 = 3.6 μm; parameters of the plasma spraying process are: main gas: Ar, auxiliary gas: H2, carrier gas: N2, spraying distance is 70 mm, spraying power is 50 KW, and spraying thickness is 60 nm.

[0046] In the modified ternary positive electrode material prepared above, the weight ratio of the ternary positive electrode material base and the coating layer is 100:0.1, the weight ratio of the microporous polymer formed by the polymerization of the first component tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde in the coating layer and the second component high entropy aluminate is 1:1; in the second component, the ratio of the sum of the molar amounts of aluminum element and rare earth element is 3:5.

[0047] Example 2

[0048] S1: 9 mg of tetraamino copper phthalocyanine and 6 mg of biphenyl dicarboxaldehyde are dissolved in 1.5 mL of N-methylpyrrolidone and placed in a Pyrex reaction tube. The tube is subjected to three cycles of freeze-vacuum-thaw operation to dry and remove any small amount of water molecules that may be present. The Pyrex reaction tube is then heat-sealed to place the system in an inert atmosphere. The heat-sealed Pyrex reaction tube is heated to carry out a polymerization reaction to obtain a reaction mixture, wherein the polymerization reaction temperature is 180°C and the polymerization reaction time is 2 days. After the reaction is completed, the system is naturally cooled to room temperature, the reaction mixture is centrifuged and washed 5 times with N'N-dimethylformamide (at this time, the washing liquid is colorless), and the resulting solid component is dried at 60°C for 30 hours to obtain a microporous polymer formed by the polymerization of tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde.

[0049] S2: Preparation of high entropy aluminate: (Y 0.2 Yb 0.2 Lu 0.2 Eu 0.2 Er 0.2 )3Al5O 12: Y2O3, Yb2O3, Lu2O3, Eu2O3, Er2O3 and Al2O3 powders are mixed in the molar ratio described in the formula, and ball-milled for 6 hours with anhydrous ethanol as a solvent to obtain a mixed slurry with a solid content of 15%; the solid-liquid slurry is separated, and the obtained solid component is dried at 80°C for 5 hours, sieved through a 300-mesh screen, and then placed in a vacuum deposition chamber as a raw target and deposited by electron beam evaporation to form a high-entropy aluminate film, wherein the parameters of the electron beam evaporation deposition process are: electron beam voltage of 1kV, current of 3A, deposition time of 20min, and the thickness of the obtained high-entropy aluminate film is 200nm. The obtained high-entropy aluminate film is sintered, crushed and sieved in sequence to obtain a high-entropy aluminate (Y 0.2 Yb 0.2 Lu 0.2 Eu 0.2 Er 0.2 )3Al5O 12 ; The sintering temperature is 1200℃, the sintering time is 15h, and the obtained high entropy aluminate particle size is 35nm.

[0050] S3: The microporous polymer prepared above and formed by polymerization of tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde and high entropy aluminate are mixed with ethanol and grinding balls in a weight ratio of 1:1:5:5 and milled to obtain a mixed material; the mixed material is applied to the surface of the ternary cathode material substrate by plasma spraying to obtain a modified ternary cathode material. The chemical formula of the ternary cathode material substrate is: LiNi 0.7 Co 0.1 Mn 0.2 O2, particle size: D50 = 3.6 μm; parameters of the plasma spraying process are: main gas: Ar, auxiliary gas: H2, carrier gas: N2, spraying distance is 70 mm, spraying power is 50 KW, and spraying thickness is 20 nm.

[0051] In the modified ternary positive electrode material prepared above, the weight ratio of the ternary positive electrode material base and the coating layer is 100:0.1, the weight ratio of the microporous polymer formed by the polymerization of the first component tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde in the coating layer and the second component high entropy aluminate is 1:1; in the second component, the ratio of the sum of the molar amounts of aluminum element and rare earth element is 3:5.

[0052] Example 3

[0053] S1: 64 mg of tetraamino copper phthalocyanine and 86 mg of biphenyl dicarboxaldehyde were dissolved in 1.5 mL of dimethyl sulfoxide and placed in a Pyrex reaction tube. The tube was subjected to three cycles of freeze-vacuum-thaw operation. After drying to remove any small amount of water molecules that may be present, the Pyrex reaction tube was heat-sealed to place the system in an inert atmosphere. The heat-sealed Pyrex reaction tube was heated to carry out a polymerization reaction to obtain a reaction mixture, wherein the polymerization reaction temperature was 120°C and the polymerization reaction time was 5 days. After the reaction was completed, the system was naturally cooled to room temperature, the reaction mixture was centrifuged and washed 3 times with N'N-dimethylformamide (at this time, the washing liquid was colorless), and the resulting solid component was dried at 80°C for 20 hours to obtain a microporous polymer formed by the polymerization of tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde.

[0054] S2: Preparation of high entropy aluminate: (Y 0.2 Yb 0.2 Lu 0.2 Eu 0.2 Er 0.2 )3Al5O 12 : Y2O3, Yb2O3, Lu2O3, Eu2O3, Er2O3 and Al2O3 powders are mixed in the molar ratio described in the formula, and ball-milled for 6 hours with anhydrous ethanol as a solvent to obtain a mixed slurry with a solid content of 40%; the solid-liquid slurry is separated, and the obtained solid component is dried at 60°C for 12 hours. After sieving through a 300-mesh sieve, it is placed in a vacuum deposition chamber as a raw target and deposited by electron beam evaporation to form a high-entropy aluminate film, wherein the parameters of the electron beam evaporation deposition process are: electron beam voltage of 1kV, current of 3A, deposition time of 20min, and the thickness of the obtained high-entropy aluminate film is 200nm. The obtained high-entropy aluminate film is sintered, crushed and sieved in sequence to obtain a high-entropy aluminate (Y 0.2 Yb 0.2 Lu 0.2 Eu 0.2 Er 0.2 )3Al5O 12 ; The sintering temperature is 1800℃, the sintering time is 8h, and the obtained high entropy aluminate particle size is 150nm.

[0055] S3: The microporous polymer prepared above and formed by polymerization of tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde and high entropy aluminate are mixed with ethanol and grinding balls in a weight ratio of 0.1:1:3:3 and milled to obtain a mixed material; the mixed material is applied to the surface of the ternary cathode material substrate by plasma spraying to obtain a modified ternary cathode material. The chemical formula of the ternary cathode material substrate is: LiNi 0.7 Co 0.1 Mn 0.2O2, particle size: D50 = 3.6 μm; parameters of the plasma spraying process are: main gas: Ar, auxiliary gas: H2, carrier gas: N2, spraying distance is 120 mm, spraying power is 30 KW, and spraying thickness is 200 nm.

[0056] In the modified ternary positive electrode material prepared above, the weight ratio of the ternary positive electrode material base and the coating layer is 100:0.1, the weight ratio of the microporous polymer formed by the polymerization of the first component tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde in the coating layer and the second component high entropy aluminate is 0.1:1; in the second component, the ratio of the sum of the molar amounts of aluminum element and rare earth element is 3:5.

[0057] Example 4

[0058] The difference between Example 4 and Example 1 is that when preparing the modified ternary positive electrode material in step S3, the microporous polymer formed by the polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde and the high entropy aluminate are mixed with ethanol and grinding balls in a weight ratio of 0.8:0.2:4:4.

[0059] Example 5

[0060] The difference between Example 5 and Example 1 is that in step S2, when preparing high entropy aluminate, the parameters of the electron beam evaporation deposition process are: electron beam voltage of 3 kV, current of 5 A, deposition time of 3 min, and thickness of the high entropy aluminate film of 20 nm. The obtained high entropy aluminate film is sintered, crushed and sieved in sequence to obtain high entropy aluminate (Y 0.2 Yb 0.2 Lu 0.2 Eu 0.2 Er 0.2 )3Al5O 12 ; The sintering temperature is 1800℃, the sintering time is 8h, and the obtained high entropy aluminate particle size is 150nm.

[0061] Example 6

[0062] The difference between Example 6 and Example 1 is that in step S3, in preparing the modified ternary positive electrode material, the weight ratio of the ternary positive electrode material substrate and the coating layer is 100:1.

[0063] Example 7

[0064] The difference between Example 7 and Example 1 is that in step S3, in preparing the modified ternary positive electrode material, the weight ratio of the ternary positive electrode material substrate and the coating layer is 100:0.01.

[0065] Example 8

[0066] The difference between Example 8 and Example 1 is that in step S3, in preparing the modified ternary positive electrode material, the weight ratio of the ternary positive electrode material substrate and the coating layer is 100:2.

[0067] Example 9

[0068] The difference between Example 9 and Example 1 is that the chemical formula of the ternary positive electrode material base is: LiNi 0.7 Co 0.2 Mn 0.1 O2, particle size: D50 = 12 μm.

[0069] Example 10

[0070] The difference between Example 10 and Example 1 is that the chemical formula of the ternary positive electrode material base is: LiNi 0.9 Co 0.05 Mn 0.05 O2, particle size: D50 = 2.5 μm.

[0071] Example 11

[0072] The difference between Example 11 and Example 1 is that when preparing the modified ternary positive electrode material in step S3, the microporous polymer formed by the polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde and the high entropy aluminate are mixed with ethanol and grinding balls in a weight ratio of 0.1:1:4:4.

[0073] Example 12

[0074] The difference between Example 12 and Example 1 is that when preparing the modified ternary positive electrode material in step S3, the weight ratio of the microporous polymer formed by polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde to the high entropy aluminate is 1:0.1:5:5.

[0075] Example 13

[0076] The difference between Example 13 and Example 1 is that the weight ratio of the ternary positive electrode material substrate to the coating layer is 100:3, and the weight ratio of the first component to the second component in the coating layer is 0.01:1.

[0077] Comparative Example 1

[0078] S1: 50 mg of tetraamino copper phthalocyanine and 25 mg of biphenyl dicarboxaldehyde are dissolved in 1.5 mL of N'N-dimethylacetamide, placed in a Pyrex reaction tube, and subjected to three cycles of freeze-vacuum-thaw operation. After drying to remove any small amount of water molecules that may be present, the Pyrex reaction tube is heat-sealed to place the system in an inert atmosphere. The heat-sealed Pyrex reaction tube is heated to carry out a polymerization reaction to obtain a reaction mixture, wherein the polymerization reaction temperature is 150°C and the polymerization reaction time is 3 days. After the reaction is completed, the system is naturally cooled to room temperature, the reaction mixture is centrifuged and washed with N'N-dimethylformamide 5 times (at this time, the washing liquid is colorless), and the resulting solid component is dried at 75°C for 24 hours to obtain a microporous polymer formed by the polymerization of tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde.

[0079] S2: The microporous polymer prepared above and formed by polymerization of tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde and the ternary cathode material base are dispersed in N'N-dimethylacetamide solution, ultrasonically mixed and stirred for 30 minutes, and after solid-liquid separation, the obtained solid component is dried to obtain a modified ternary material. The chemical formula of the ternary cathode material base is: LiNi 0.7 Co 0.1 Mn 0.2 O2, particle size: D50 = 3.6 μm; in the modified ternary material prepared above, the mass ratio of the microporous polymer to the ternary positive electrode material substrate is 100:0.1.

[0080] Comparative Example 2

[0081] S1: Preparation of high entropy aluminate: (Y 0.2 Yb 0.2 Lu 0.2 Eu 0.2 Er 0.2 )3Al5O 12 : Y2O3, Yb2O3, Lu2O3, Eu2O3, Er2O3 and Al2O3 powders are mixed in the molar ratio described in the formula, and ball-milled for 6 hours with anhydrous ethanol as a solvent to obtain a mixed slurry with a solid content of 15%; the solid-liquid slurry is separated, and the obtained solid component is dried at 80°C for 5 hours, sieved through a 300-mesh screen, and then placed in a vacuum deposition chamber as a raw target and deposited by electron beam evaporation to form a high-entropy aluminate film, wherein the parameters of the electron beam evaporation deposition process are: electron beam voltage of 1kV, current of 3A, deposition time of 20min, and the thickness of the obtained high-entropy aluminate film is 200nm. The obtained high-entropy aluminate film is sintered, crushed and sieved in sequence to obtain a high-entropy aluminate (Y 0.2 Yb 0.2 Lu 0.2 Eu 0.2 Er0.2 )3Al5O 12 ; The sintering temperature is 1500℃, the sintering time is 10h, and the obtained high entropy aluminate particle size is 50nm.

[0082] S2: The high entropy aluminate prepared above is mixed with ethanol and grinding balls in a weight ratio of 1:4:4 and subjected to ball milling to obtain a mixed material; the mixed material is applied to the surface of the ternary cathode material substrate by plasma spraying to obtain a modified ternary cathode material. The chemical formula of the ternary cathode material substrate is: LiNi 0.7 Co 0.1 Mn 0.2 O2, particle size: D50 = 3.6 μm; parameters of the plasma spraying process are: main gas: Ar, auxiliary gas: H2, carrier gas: N2, spraying distance is 70 mm, spraying power is 50 KW, and spraying thickness is 60 nm.

[0083] In the modified ternary positive electrode material prepared above, the weight ratio of the ternary positive electrode material substrate and the high entropy aluminate is 100:0.1.

[0084] Comparative Example 3

[0085] In Comparative Example 3, the ternary positive electrode material substrate before modification in Example 1 was directly used as the ternary positive electrode material.

[0086] Coin-type batteries were prepared using the modified ternary cathode materials prepared in Examples 1 to 13, Comparative Examples 1 and 2, and the unmodified ternary cathode material in Comparative Example 3 as the positive electrode active material. The assembled coin-type batteries were then left to rest for 4 hours before electrochemical performance testing. The voltage range was 2.8-4.5 V. Specific charge and discharge data are shown in Table 1.

[0087] Specifically, the preparation steps of the button battery include: lithium sheet as the negative electrode, superconducting carbon black Super P as the conductive agent, polyvinylidene fluoride (PVDF) as the binder, and N-methylpyrrolidone (NMP) as the solvent. The positive electrode active material and superconducting carbon black Super P are ground and then added to a solution of N-methylpyrrolidone dissolved in polyvinylidene fluoride. The mass ratio of the positive electrode active material, binder, and conductive agent is 90:5:5. After stirring for 2 hours, the slurry viscosity is adjusted to 45%. The slurry is then coated on the surface of a 20μm thick aluminum foil and then vacuum dried at 110°C for 20 hours. The dried electrode was rolled, sliced, and weighed, and then assembled with a metal lithium sheet and a separator prepared by a wet process in an argon atmosphere glove box into a CR2016 button battery. The electrolyte was 1.0 mol / L LiPF6 / EC+DEC+EMC, where EC was vinylene carbonate, DEC was diethyl carbonate, and EMC was ethyl methyl carbonate (the electrolyte was purchased, and its model was: Sanyuan Tianci TC-E858-15B).

[0088] Battery performance test:

[0089] For the test of battery capacity: For the test of the corresponding battery capacity in the examples and comparative examples, the 0.2C first-week discharge capacity was first tested at 25°C, and then the gram capacity of 0.33 and 1C batteries was tested at 25°C respectively. The ratio of the capacity of a lithium-ion battery at 1C to the 0.2C first-week discharge capacity is the rate performance of the battery. In addition, the battery capacity (1C-50th) after 50 cycles of the battery was also tested, and the test condition was 25°C. The first efficiency of the battery: the ratio of the 0.2C first discharge capacity to the 0.2C first charging capacity; Battery cycle stability test: the 50-week cycle capacity retention rate of the lithium-ion battery was tested at 25°C.

[0090] Table 1

[0091]

[0092]

[0093] After fully charging the assembled button cells, they were disassembled to obtain samples of the modified cathode material. DSC data for these samples was then analyzed. Low exothermic enthalpy and high exothermic peak temperature indicate a safer lithium-ion battery. These test data reflect the battery's safety performance. The results are shown in Table 2.

[0094] Table 2

[0095]

[0096]

[0097] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0098] In Examples 1 to 13, the method proposed in the present invention for modifying the ternary positive electrode material by compounding the microporous polymer formed by the polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde and the high entropy aluminate as the coating layer material of the ternary positive electrode material base was used, and the prepared modified ternary positive electrode materials were used in lithium-ion batteries. According to the data in Tables 1 and 2, the battery capacity, cycle stability and safety performance of the lithium-ion battery were effectively improved. In particular, in Examples 1 to 12, the parameters in the preparation process of the modified ternary positive electrode material were controlled within the preferred range, and the corresponding lithium-ion battery had better electrochemical performance and safety.

[0099] In contrast, in the comparative examples, only a microporous polymer formed by polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde was used in the modification of the ternary cathode material in Comparative Example 1, and only a high-entropy aluminate was used in the modification of the ternary cathode material in Comparative Example 2. The corresponding lithium-ion battery's cycle stability and safety were significantly different from those in the embodiments of the present invention. In particular, the corresponding lithium-ion battery's safety performance was very poor, posing a significant safety risk. Comparative Example 3 used an unmodified ternary cathode material, and the electrochemical performance and safety of the corresponding lithium-ion battery were even further behind those in the embodiments of the present invention.

[0100] In addition, the discharge capacity change of the button-type battery obtained by using the modified ternary cathode material prepared in Example 1, Comparative Example 1 and Comparative Example 2 as the cathode active material after 50 cycles was plotted. The results are shown in FIG. Figure 1 As shown. Figure 1 It can be seen that the lithium ion battery corresponding to Example 1 has a better battery capacity and better cycle stability. The stability of the lithium ion batteries corresponding to Comparative Examples 1 and 2 is much lower than that of Example 1. Further, the DSC curves of the modified ternary cathode materials corresponding to Example 1, Comparative Examples 1 and 2 were plotted, and the results are shown in FIG. Figure 2 As shown by Figure 2 It can be seen that the safety performance of the lithium ion battery corresponding to Example 1 is better, and the safety performance of the lithium ion batteries corresponding to Comparative Examples 1 and 2 is far inferior to that of the lithium ion battery corresponding to Example 1.

[0101] In summary, the present invention uses a composite of a microporous polymer formed by the polymerization of tetraaminocopper phthalocyanine and biphenyldicarboxaldehyde and a high-entropy aluminate as a coating layer for the base of the ternary positive electrode material, which can give full play to the respective advantages of the above two components, and under the synergistic effect of the two, it can also enable the modified ternary positive electrode material to have good energy density and electrical conductivity while not being prone to heat conduction and heat transfer, which is beneficial to improving the stability and safety of the modified ternary positive electrode material, thereby enabling the modified ternary positive electrode material to have better stability and safety in lithium-ion batteries.

[0102] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A modified ternary cathode material, characterized in that: The modified ternary positive electrode material comprises a ternary positive electrode material substrate and a coating layer coated on the surface of the ternary positive electrode material substrate; The coating layer includes a first component and a second component, the first component is a microporous polymer formed by polymerization of tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde, and the second component is high entropy aluminate.

2. The modified ternary cathode material according to claim 1, characterized in that The weight ratio of the ternary positive electrode material substrate to the coating layer is 100:(0.01-2); And / or, the weight ratio of the first component to the second component in the coating layer is (0.1-10):

1.

3. The modified ternary cathode material according to claim 1, characterized in that The weight ratio of the ternary positive electrode material substrate to the coating layer is 100:(0.1-1); And / or, the weight ratio of the first component to the second component in the coating layer is (1-5):

1.

4. The modified ternary cathode material according to any one of claims 1 to 3, characterized in that When the tetraamino copper phthalocyanine and the biphenyl dicarboxaldehyde are polymerized to form the microporous polymer, the polymerization temperature is 120 to 180° C. and the polymerization time is 2 to 5 days; and / or, when the tetraamino copper phthalocyanine and the biphenyl dicarboxaldehyde are polymerized to form the microporous polymer, the molar ratio of the tetraamino copper phthalocyanine to the biphenyl dicarboxaldehyde is 1:(2-4); and / or, the pore size of the microporous polymer is 2 to 50 nm; And / or, the high entropy aluminate is obtained by sintering aluminum oxide and at least five rare earth oxides; preferably, the rare earth oxides are at least five of lanthanum oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, scandium oxide and yttrium oxide; and / or, the rare earth oxide is the ytterbium oxide, the yttrium oxide, the europium oxide, the lutetium oxide and the erbium oxide; And / or, the sintering temperature is 1200-1800° C. and the sintering time is 8-15 hours; And / or, in the high entropy aluminate, the molar amounts of the rare earth elements are equal, and the ratio of the sum of the molar amounts of the aluminum element and the rare earth element is (2-4):

5.

5. The modified ternary cathode material according to any one of claims 1 to 3, characterized in that: The chemical formula of the ternary cathode material substrate is LiNi x Co y Mn (1-x-y) O2, wherein 0.5≤x<1.0, 0<y≤0.2, and x+y<1; the particle size of the ternary positive electrode material substrate is 2.5μm≤D50≤12μm.

6. A method for preparing the modified ternary cathode material according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: Dissolving tetraamino copper phthalocyanine and biphenyl dicarboxaldehyde in a first organic solvent, and performing a polymerization reaction in an inert gas atmosphere to obtain a reaction mixture; centrifuging, washing, and first drying the reaction mixture to obtain a microporous polymer; Aluminum oxide and at least five rare earth oxides are first ball-milled in a second organic solvent to obtain a mixed slurry; the mixed slurry is separated, the obtained solid component is subjected to a second drying, and then deposited by electron beam evaporation to form a high-entropy aluminate film; the high-entropy aluminate film is sequentially sintered, crushed, and sieved to obtain a high-entropy aluminate; Mixing the microporous polymer and the high entropy aluminate through a second ball milling process to obtain a mixed material; The mixed material is coated on the surface of the ternary positive electrode material substrate by plasma spraying to obtain the modified ternary positive electrode material.

7. The method for preparing the modified ternary cathode material according to claim 6, characterized in that: The molar ratio of the tetraamino copper phthalocyanine to the biphenyl dicarboxaldehyde is 1:(2-4); And / or, the polymerization reaction temperature is 120-180° C., and the polymerization reaction time is 2-5 days; And / or, the number of washing is 3 to 5 times, and the washing solvent is N'N-dimethylformamide; and / or, the first organic solvent is one or more of N'N-dimethylacetamide, N'N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone; and / or, the temperature of the first drying is 60 to 110° C., and the time of the first drying is 20 to 30 hours; And / or, the concentration of the mixed solution obtained by dissolving the tetraaminocopper phthalocyanine and the biphenyldicarboxaldehyde in the first organic solvent is 0.01 to 0.1 g / mL.

8. The method for preparing the modified ternary cathode material according to claim 6, characterized in that: The rare earth oxides are at least five of lanthanum oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, scandium oxide and yttrium oxide; And / or, the rare earth oxide is the ytterbium oxide, the yttrium oxide, the europium oxide, the lutetium oxide and the erbium oxide.

9. The method for preparing the modified ternary cathode material according to any one of claims 6 to 8, characterized in that: The second drying temperature is 60 to 80° C., and the second drying time is 5 to 12 hours; And / or, the electron beam voltage is 1-3 kV, the electron beam current is 3-5 A, and the deposition time is 3-20 min; and / or, the thickness of the high entropy aluminate film is 20 to 200 nm; and / or, the second organic solvent is ethanol; and / or, the particle size of the high entropy aluminate is 30 to 150 nm; And / or, the sintering temperature is 1200-1800° C., and the sintering time is 8-15 hours; And / or, the second ball milling process includes mixing the microporous polymer and the high entropy aluminate with ethanol and grinding balls, and then performing the second ball milling mixing operation; preferably, the weight ratio of the microporous polymer and the high entropy aluminate to ethanol and grinding balls is (0.1~1):(0.1~1):(3~5):(3~5).

10. The method for preparing the modified ternary cathode material according to any one of claims 6 to 8, characterized in that: The parameters of the plasma spraying process are: main gas: Ar, auxiliary gas: H2, carrier gas: N2, spraying distance is 70-120 mm, spraying power is 30-50 KW, and spraying thickness is 20-200 nm; And / or, the parameters of the electron beam evaporation deposition process are: electron beam voltage of 1 to 3 kV, current of 3 to 5 A, and deposition time of 3 to 20 min.

11. A lithium-ion battery, characterized in that: The lithium-ion battery comprises the modified ternary positive electrode material according to any one of claims 1 to 5; or, the lithium-ion battery comprises the modified ternary positive electrode material prepared by the preparation method of the modified ternary positive electrode material according to any one of claims 6 to 10.

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