A high-nickel ternary positive electrode coating material, a preparation method and application thereof

Abstract

This invention provides a high-nickel ternary cathode coating material, its preparation method, and its application, relating to the field of lithium-ion battery technology. This invention innovatively designs and prepares a novel aluminosilicate compound containing five main elements—Al, Mg, P, Si, and Li—as a cathode coating material. This material possesses multiple functions, including lithium replenishment, residual alkali reduction, enhanced ion conduction, and improved structural stability. It can efficiently modify finished high-nickel ternary cathode materials, simultaneously improving battery capacity and safety.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a high-nickel ternary cathode coating material and its preparation method, as well as the application of the coating material in the modification of finished high-nickel ternary cathode materials. Background Technology

[0002] High-nickel ternary cathode materials (such as 90505 type, LiNi) 0.9 Co 0.05 Mn 0.05 O2 (O2) is a core material for improving the energy density of lithium-ion batteries due to its high specific capacity, and it has broad application prospects in the field of power batteries. However, high-nickel ternary materials have inherent defects such as high residual alkali content on the surface, loss of active lithium, and poor interface stability, which can easily trigger battery side reactions, resulting in rapid capacity decay and insufficient thermal safety. These problems need to be solved through surface coating modification.

[0003] Coating materials (additives) are the core of high-nickel ternary cathode material modification, and their performance directly determines the modification effect. Existing high-nickel ternary cathode coating materials face several technical bottlenecks: First, they have limited functionality; most coating materials can only achieve single functions such as structural stabilization or residual alkali reduction, failing to simultaneously achieve multiple effects such as lithium replenishment and enhanced ion conduction, resulting in modified cathode materials that struggle to balance capacity and safety. Second, they have poor compatibility; existing aluminosilicates are generally only used in ceramics, building materials, or simple fillings, and have not been designed as multifunctional coating agents suitable for high-nickel cathodes. Furthermore, they lack targeted preparation processes, making it difficult to form a uniform and stable coating layer. Third, the preparation process is complex; existing multifunctional coating materials often employ multi-step synthesis, resulting in cumbersome processes, high costs, and low industrialization feasibility. Fourth, they have poor adhesion to the finished high-nickel cathode material, leading to easy detachment of the coating layer and short-lived modification effects.

[0004] Furthermore, existing high-nickel ternary cathode modification technologies mostly focus on optimizing the modification process, while neglecting the structural design and preparation technology innovation of the coating material itself, resulting in limited improvement in modification effect. Therefore, developing a novel aluminosilicate coating material (additive) with integrated functions, strong adaptability, simple preparation process, and low cost, and providing its efficient preparation method, has become a key requirement for solving the performance bottleneck of high-nickel ternary cathode materials. Summary of the Invention

[0005] In view of the many shortcomings of existing coating materials and their preparation methods, this invention innovatively designs a novel multifunctional aluminosilicate coating material containing five main elements: Al, Mg, P, Si, and Li. Its preparation process is optimized to achieve functional integration and performance improvement, while simplifying the preparation process and reducing costs, thus resolving the core contradictions of existing technologies. Furthermore, this material is provided for application in the modification of finished high-nickel ternary cathode materials, achieving a simultaneous and significant improvement in both the capacity and safety of the cathode material.

[0006] One of the objectives of this invention is to provide a method for preparing a high-nickel ternary cathode coating material.

[0007] The second objective of this invention is to provide a high-nickel ternary cathode coating material prepared by this method.

[0008] The third objective of this invention is to provide an application of the high-nickel ternary cathode coating material in the modification of finished high-nickel ternary cathode materials.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a method for preparing a high-nickel ternary cathode coating material, comprising the following steps: (1) Add lithium source, magnesium source, aluminum source and phosphorus source to deionized water, stir until completely dissolved, control the solution temperature at 50~60℃, add citric acid, stir for 30~60min to form a uniform metal ion complex solution; slowly add silicon source to the metal ion complex solution at a dropping rate of 1~2 drops / second, while stirring continuously. After the addition is complete, continue stirring for 1~2h, adjust the pH value of the solution to 3~4, keep warm at 30~40℃, and stir until a transparent sol is formed; the elemental molar ratio of lithium, magnesium, aluminum, silicon and phosphorus is Li:Mg:Al:Si:P=0.8-1.5:0.3-0.8:0.1-0.3:1.05-1.7:0.2-0.5; (2) Place the transparent sol in a constant temperature drying oven and keep it at 60~80℃ for 12~24h to allow the sol to slowly dehydrate and form a gel; take out the gel and age it at room temperature for 24~48h. (3) Place the aged gel in an oven and dry it at 100~120℃ for 4~6h to remove residual moisture and organic impurities; transfer the dried gel into an atmosphere muffle furnace, introduce air as a protective atmosphere, with an air flow rate of 50~80mL / min, heat it to 500~600℃ at a heating rate of 3~5℃ / min, keep it at that temperature for 3~5h, cool it to room temperature, grind it, and pass it through a 200~300 mesh sieve to obtain a novel aluminosilicate coated material.

[0010] In some embodiments, the lithium source is selected from lithium carbonate (Li2CO3) or lithium nitrate (LiNO3), the magnesium source is selected from magnesium oxide (MgO) or magnesium nitrate (Mg(NO3)2·6H2O), the aluminum source is selected from aluminum oxide (Al2O3) or aluminum isopropoxide (Al(OC3H7)3), the silicon source is selected from tetraethyl orthosilicate (TEOS) or sodium silicate (Na2SiO3), and the phosphorus source is selected from ammonium dihydrogen phosphate (NH4H2PO4) or phosphoric acid (H3PO4). In some embodiments, the molar ratio of citric acid to all metal ions is 1.2 to 1.5:1; The chemical formula of the novel aluminosilicate coated material prepared is Li a Mg b Al c Si d P e O ζ • nSiO2 (n is the degree of polymerization of silicon-oxygen tetrahedra, 0.5≤n≤2.0, preferably 1.0≤n≤1.5), 0.8≤a≤1.5, 0.3≤b≤0.8, 0.1≤c≤0.3, 0.05≤d≤0.2, 0.2≤e≤0.5, ζ is the molar percentage of oxygen element, satisfying charge balance, i.e. ζ=(a+2b+3c+4d+5e) / 2; the material uses silicon-oxygen tetrahedra (SiO4) and aluminum-oxygen tetrahedra (AlO4) as basic structural units, with Mg, Li, and P elements uniformly doped in the lattice, and the particle size is 50~500nm, with excellent dispersibility, and has multiple functions such as lithium replenishment, residual alkali reduction, enhanced ion conduction, and improved structural stability.

[0011] A novel multifunctional aluminosilicate coated material was prepared by the sol-gel method. This method is simple, energy-efficient, and can achieve uniform doping of various elements to form a stable silicon-oxygen / aluminum-oxygen tetrahedral framework structure.

[0012] Secondly, the present invention provides a high-nickel ternary cathode coating material prepared by the above preparation method.

[0013] Thirdly, the present invention provides an application of the above-mentioned high-nickel ternary cathode coating material in the modification of finished high-nickel ternary cathode materials.

[0014] In some implementations, the application includes the following steps: (a) Raw material mixing: The finished high-nickel ternary cathode material and the high-nickel ternary cathode coating material are put into a ball mill at a mass ratio of 99.5:0.5~99.9:0.1, with agate balls as the grinding medium, a ball-to-material ratio of 20:1~30:1, a rotation speed of 200~300 r / min, and a ball milling time of 30~60 min to obtain a uniformly mixed powder; (b) Solid-state sintering: The mixed powder is placed in an atmosphere muffle furnace, and oxygen is introduced as a protective atmosphere at a flow rate of 50~100 mL / min. The temperature is raised to 350℃ at a heating rate of 5~10℃ / min, held for 2~4 hours, and then cooled to room temperature with the furnace to obtain the modified high-nickel ternary cathode material.

[0015] In some embodiments, the finished high-nickel ternary cathode material in step (a) can be NCM811, NCM90505, NCM955, etc., preferably the finished 90505 high-nickel ternary cathode material with a specific capacity of 210mAh / g and a pyrochemical oxygen release temperature of 225℃.

[0016] This sintering process enables the aluminosilicate coating material to form a uniform coating layer that is tightly bonded to the substrate surface. Its silicon-aluminum tetrahedral framework can form a stable ion conduction channel, giving full play to its multifunctional modification effect.

[0017] The modified high-safety, high-nickel ternary cathode material can be further assembled with a graphite anode, a polyolefin separator, and an electrolyte to obtain a lithium-ion battery.

[0018] After modification, the aluminosilicate coating material prepared using this invention can achieve a specific capacity of 220 mAh / g for high-nickel ternary cathode materials, with the pyrochemical oxygen release temperature increased to 240℃. The assembled lithium-ion battery exhibits excellent thermal stability and stable cycle performance, with a capacity retention rate of ≥90% after 500 cycles at 1C rate, making it suitable for various high-energy-density battery products. Specifically, the Li element in the coating material can provide lithium replenishment, compensating for active lithium loss; the Mg element can be doped into the aluminosilicate lattice, enhancing structural stability and synergistically increasing the thermal decomposition temperature of the material with the Al element, thus improving thermal safety; the P element can react with residual alkali (LiOH, Li2CO3) on the material surface, reducing the residual alkali content and minimizing interfacial side reactions; the framework structure composed of silicon-oxygen tetrahedra and aluminum-oxygen tetrahedra optimizes the lithium-ion conduction channels, improving rate performance, while simultaneously forming a dense coating layer to prevent electrolyte erosion.

[0019] The core innovation of this invention lies in breaking through the conventional technological inertia of high-nickel ternary cathodes, which prioritize "modification processes," "single-function coating materials," and "unfunctionalized aluminosilicate materials." It focuses on the structural design and preparation technology innovation of the coating material itself, forming a triple innovation: "novel multifunctional aluminosilicate coating material + precise preparation process + finished product modification and application." Innovative coating material structure: A novel aluminosilicate compound containing five main elements, Al, Mg, P, Si, and Li, is innovatively designed. The core molar ratio range and silicon-oxygen / aluminosilicate tetrahedral framework structure are clearly defined. Functional integration is achieved through uniform doping of Mg, Li, and P elements. This solves the technical problem that traditional single / binary coating materials and ordinary aluminosilicates cannot simultaneously achieve lithium replenishment, residual alkali reduction, structural stabilization, and conduction promotion. It is also suitable for the modification needs of high-nickel ternary cathode materials. Innovation in coating material preparation process: Aluminosilicate coating materials are prepared by sol-gel method. The selection of precursors, complexation conditions, sol-gel conversion parameters and sintering process are optimized and determined to achieve uniform doping of each element. The resulting coating material has uniform particles, good dispersibility and stable structure. Compared with the traditional solid-state sintering method, energy consumption is reduced by more than 30%, the preparation process is simplified, the cost is reduced by 20% and the material performance is better. Application Strategy Innovation: The novel aluminosilicate coating material prepared is used to modify the finished high-nickel ternary cathode material. Without modifying the bulk structure of the cathode material, efficient modification can be achieved simply through ball milling and low-temperature sintering. It has strong process compatibility and can be directly adapted to existing production lines. It solves the problems of poor bonding between existing coating materials and cathode materials and short-term modification effects, while giving full play to the multiple functional advantages of the coating material.

[0020] Beneficial effects: 1. High integration of coating materials: The new aluminosilicate coating material integrates four functions through precise element doping and structural design: lithium replenishment, residual alkali reduction, enhanced ion conduction, and improved structural stability. After modification, the specific capacity of the high-nickel ternary cathode material increases from 210mAh / g to 220mAh / g (an increase of 4.8%), the pyrolysis oxygen temperature increases from 225℃ to 240℃ (an increase of 6.7%), the residual alkali content is reduced by ≥30%, and the capacity retention rate after 500 cycles at 1C is improved by ≥7%, effectively balancing high energy density and high safety. 2. Advanced coating material preparation process: The sol-gel method is used for preparation, which is simple, energy-efficient, and easy to operate. It can achieve uniform doping of each element, avoid component separation, and the prepared material has uniform particle size (50~200nm) and excellent dispersibility. It is tightly bonded to the surface of high-nickel ternary cathode material, and the modification effect is long-lasting. Compared with traditional preparation methods, the research and development cycle is shortened by 50%, and the industrialization feasibility is high. 3. Strong material adaptability and low cost: The chemical composition and crystal structure of the new aluminosilicate coating material are specifically designed for high-nickel ternary cathode materials, with excellent adaptability. It can be used for the modification of various finished high-nickel ternary materials. The precursors used in the preparation are all conventional chemical raw materials, which are widely available and inexpensive. Under large-scale production, the unit material cost is reduced by more than 15%. 4. Good compatibility of modification process: Adopting the "post-finished product modification" strategy, there is no need to modify the bulk synthesis process of high-nickel ternary cathode material. Only ball milling and low-temperature solid-state sintering steps are added. It can be directly adapted to existing high-nickel ternary material production lines without large-scale equipment modification. The production efficiency is high and the yield is ≥95%. The 350℃ low-temperature sintering process further reduces energy consumption and avoids the problem of ion conduction obstruction caused by excessive crystallization of the coating layer. 5. Outstanding technological innovation: Compared with existing single / binary coating materials and ordinary aluminosilicate materials, the novel aluminosilicate coating material of this invention has significant innovations in structural design, functional integration and preparation process. It solves the technical pain points of existing coating materials, such as single function, complex preparation, poor adaptability and limited modification effect, and has unique technical advantages and industrial application value.

[0021] The present invention has been described in detail above; however, the above embodiments are merely illustrative in nature and are not intended to limit the invention. Furthermore, this document is not limited to the foregoing prior art or the invention itself, or to any theory described in the following embodiments. Attached Figure Description

[0022] Figure 1 The images show the SEM morphology of the coating material obtained in Example 1, with (a) being a morphology image at 10,000x magnification and (b) being a morphology image at 40,000x magnification. Figure 2 The XRD diffraction pattern of the coating material obtained in Example 1; Figure 3 The images show the SEM morphology of the high-nickel ternary cathode material before and after coating in Example 1. (a) is the morphology of the cathode before coating at 50,000x magnification, (b) is the morphology of the cathode before coating at 20,000x magnification, (c) is the morphology of the cathode after coating at 50,000x magnification, and (d) is the morphology of the cathode after coating at 20,000x magnification. Detailed Implementation

[0023] The present invention will be further described below with reference to the embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0024] Unless otherwise specified, the raw materials, reagents, and methods used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0025] Example 1 (1) Preparation of aluminosilicate coating material: ① Raw material preparation: Select 0.03 mol lithium carbonate (Li2CO3), 0.025 mol magnesium nitrate (Mg(NO3)2·6H2O), 0.01 mol aluminum isopropoxide (Al(OC3H7)3), 0.065 mol tetraethyl orthosilicate (TEOS) (total Si content 0.065 mol, where n=1.2, containing 0.06 mol Si), 0.015 mol ammonium dihydrogen phosphate (NH4H2PO4), 100 mL deionized water, and 0.1235 mol citric acid (molar ratio to metal ions 1.3:1, using 30% excess citric acid to complex Li2CO3). + Mg 2+ Al 3+ (Metal cations, to avoid precipitation); ② Sol preparation: Lithium carbonate, magnesium nitrate, aluminum isopropoxide, and ammonium dihydrogen phosphate were added to deionized water and stirred at 55°C for 40 min until completely dissolved. Citric acid was added and stirring was continued for 45 min to form a complex solution. Tetraethyl orthosilicate was added dropwise to the solution at a rate of 1.5 drops / second and stirred continuously for 1.5 h. The pH value was adjusted to 3.5 with dilute nitric acid and kept at 35°C for 35 min to form a transparent sol. ③ Gel aging: Place the transparent sol in a 70℃ constant temperature drying oven for 18 hours to form a gel; age at room temperature for 36 hours to remove residual moisture; ④ Drying and sintering: The gel was dried in a 110℃ oven for 5 hours, then transferred to an atmosphere muffle furnace. Air was introduced (flow rate 60 mL / min), and the temperature was increased to 550℃ at a rate of 4℃ / min. The temperature was held for 4 hours, cooled to room temperature, ground, and passed through a 250-mesh sieve to obtain a novel aluminosilicate coated material powder (chemical formula Li). 1.2 Mg 0.5 Al 0.2 Si 0.1 P 0.3 O 2.35 ·1.2SiO2).

[0026] SEM image as follows Figure 1 As shown, the prepared aluminosilicate coating material consists of near-spherical nanoparticles with a primary particle size mainly below 500 nm. The particles are uniformly dispersed, have smooth surfaces and regular contours, exhibiting excellent dispersibility and interfacial compatibility, which is beneficial for forming a uniform coating layer on the surface of the cathode material.

[0027] X-ray diffraction patterns measured using Cu-Kα radiation in the range of 10° to 80° are shown below. Figure 2 As shown, the sample exhibits characteristic diffraction peaks at 2θ = 20.4° (100), 26.1° (110), 32.6° (111), 36.7° (200), and 50.0° (211). Each peak is broadened and diffuse, which is typical of aluminosilicate structure. This indicates that a high-purity, uniformly doped Li-Mg-Al-P-Si-O aluminosilicate coating material has been successfully prepared.

[0028] (2) Application of coating materials (modification of cathode materials): ① Material preparation: 99.8g of finished 90505 high-nickel ternary cathode material (Chengbai S90E & SC92Y, specific capacity 210mAh / g, pyrochemical oxygen release temperature 225℃), 0.2g of the aluminosilicate coating material prepared above, agate ball grinding media, and oxygen; ②Preparation process: The matrix material and the coating material are put into a planetary ball mill with a ball-to-material ratio of 25:1 and a rotation speed of 250 r / min for 45 min to obtain a uniformly mixed powder; the mixed powder is loaded into an alumina crucible, placed in an atmosphere muffle furnace, oxygen is introduced (flow rate 80 mL / min), the temperature is raised to 350℃ at 8℃ / min, held at 3h, and then cooled to room temperature with the furnace to obtain the modified high-nickel ternary cathode material; SEM images before and after coating are shown below Figure 3 As shown, it can be seen that Li 1.2 Mg 0.5 Al 0.2 Si 0.1 P 0.3 O 2.35 • 1.2 SiO2 coating material forms a continuous, dense and uniform coating layer on the surface of 90505 high-nickel ternary cathode particles; the secondary cathode particles have a complete spherical morphology with no exposed sites on the surface, and the coating layer is tightly bonded to the substrate interface, which can effectively play a role in stabilizing the structure and suppressing side reactions.

[0029] ③ Battery assembly: Modified high-nickel ternary cathode material is used as the active material, mixed with conductive agent (SP) and binder (PVDF) at a mass ratio of 97:2:1, NMP solvent is added to make a slurry, which is coated on aluminum foil current collector, and then dried, rolled and cut to obtain the cathode sheet; graphite is used as the anode, Celgard 2320 is used as the separator, and 1M LiPF6 EC / EMC / DMC (volume ratio 1:1:1) solution is used as the electrolyte. The cells are assembled into a soft pack battery in an argon glove box.

[0030] Example 2 (1) Preparation of aluminosilicate coating material: ① Raw material preparation: 0.05 mol lithium nitrate (LiNO3), 0.02 mol magnesium oxide (MgO), 0.00375 mol aluminum oxide (Al2O3), 0.054 mol sodium silicate (Na2SiO3) (total Si content 0.054 mol, where n=1.0, containing 0.05 mol Si), 0.0175 mol phosphoric acid (H3PO4), 100 mL deionized water, and 0.102 mol citric acid (molar ratio to metal ions 1.2:1). ② Sol preparation: Lithium nitrate, magnesium oxide, aluminum oxide and phosphoric acid are added to deionized water and stirred at 50°C for 60 min until completely dissolved. Citric acid is added and stirring is continued for 30 min to form a complex solution. Sodium silicate is slowly added dropwise to the solution at a rate of 1 drop / second and stirred continuously for 2 h. The pH value is adjusted to 3 with dilute hydrochloric acid and kept at 30°C for 40 min to form a transparent sol. ③ Gel aging: Place the transparent sol in a 60℃ constant temperature drying oven for 24 hours to form a gel; age at room temperature for 48 hours. ④ Drying and sintering: The gel was dried in a 100℃ oven for 6 hours, then transferred to an atmosphere muffle furnace. Air was introduced (flow rate 50 mL / min), and the temperature was increased to 500℃ at 3℃ / min. The temperature was held for 5 hours, cooled to room temperature, ground, and passed through a 200-mesh sieve to obtain a novel aluminosilicate coated material powder (chemical formula Li). 1.0 Mg 0.4 Al 0.15 Si 0.08 P 0.35 O 2.16 ·1.0SiO2); (2) Application of coating materials (modification of cathode materials): ① Material preparation: 99.9g of finished 90505 high-nickel ternary cathode material (specific capacity 210mAh / g, pyrochemical oxygen release temperature 225℃), and 0.1g of the aluminosilicate coating material prepared above; ②Preparation process: The matrix material and the coating material are put into a planetary ball mill with a ball-to-material ratio of 20:1 and a rotation speed of 200 r / min for 60 min. The mixed powder is then placed in an atmosphere muffle furnace, oxygen is introduced (flow rate 50 mL / min), and the temperature is increased to 350℃ at 5℃ / min. After holding at this temperature for 4 h, the furnace is cooled to obtain the modified cathode material. ③ Battery assembly: Same as the battery assembly process in Example 1.

[0031] Example 3 (1) Preparation of aluminosilicate coating material: ① Raw material preparation: 0.0325 mol lithium carbonate (Li2CO3), 0.03 mol magnesium nitrate (Mg(NO3)2·6H2O), 0.0125 mol aluminum isopropoxide (Al(OC3H7)3), 0.0825 mol tetraethyl orthosilicate (TEOS) (total Si content 0.0825 mol, where n=1.5, containing 0.075 mol Si), 0.02 mol ammonium dihydrogen phosphate (NH4H2PO4), 100 mL deionized water, and 0.161 mol citric acid (molar ratio to metal ions 1.5:1). ② Sol preparation: Lithium carbonate, magnesium nitrate, aluminum isopropoxide, and ammonium dihydrogen phosphate were added to deionized water and stirred at 60°C for 30 min until completely dissolved. Citric acid was added and stirring was continued for 60 min to form a complex solution. Tetraethyl orthosilicate was added dropwise to the solution at a rate of 2 drops / second and stirred continuously for 1 h. The pH was adjusted to 4 with dilute nitric acid and kept at 40°C for 30 min to form a transparent sol. ③ Gel aging: Place the transparent sol in an 80℃ constant temperature drying oven for 12 hours to form a gel; age at room temperature for 24 hours. ④ Drying and sintering: The gel was dried in a 120℃ oven for 4 hours, then transferred to an atmosphere muffle furnace, air was introduced (flow rate 80 mL / min), and the temperature was increased to 600℃ at 5℃ / min, held for 3 hours, cooled to room temperature, ground, and passed through a 300-mesh sieve to obtain a novel aluminosilicate coated material powder (chemical formula Li). 1.3 Mg 0.6 Al 0.25 Si 0.15 P 0.4 O 2.925 ·1.5SiO2); (2) Application of coating materials (modification of cathode materials): ① Material preparation: 99.5g of finished 90505 high-nickel ternary cathode material (specific capacity 210mAh / g, pyrochemical oxygen release temperature 225℃), and 0.5g of the aluminosilicate coating material prepared above; ②Preparation process: The matrix material and the coating material are put into a planetary ball mill with a ball-to-material ratio of 30:1 and a rotation speed of 300 r / min for 30 min. The mixed powder is then placed in an atmosphere muffle furnace, oxygen is introduced (flow rate 100 mL / min), and the temperature is increased to 350℃ at a rate of 10℃ / min. After holding at this temperature for 2 h, the furnace is cooled to obtain the modified cathode material. ③ Battery assembly: Same as the battery assembly process in Example 1.

[0032] Comparative Example 1 Ordinary aluminosilicate (Al2Si2O7) was used as the coating material (without Li, Mg, or P doping). It was prepared by existing solid-state sintering method (using α-Al2O3 and SiO2 as raw materials, weighed at a molar ratio of Al2O3:SiO2=1:2, mixed by dry ball milling, pre-sintered at 800℃, crushed twice, and then sintered at 1200~1300℃ in air atmosphere for 6~8h, and finally ground and sieved to obtain Al2Si2O7 powder). The finished 90505 high-nickel ternary cathode material was then modified according to the application process of Example 1 to make a battery.

[0033] Comparative Example 2 According to Li 1.2 Mg 0.5 Al 0.2 Si 0.1 P 0.3 O 2.35 • 1.2 SiO2 elemental stoichiometry: Lithium carbonate, magnesium oxide, aluminum oxide, silicon dioxide, and ammonium dihydrogen phosphate solid powders were directly weighed and mixed by dry ball milling to obtain a non-synthetic physical mixed coating material. The material was then prepared by mechanical grinding and modified according to the application process of Example 1 to produce the finished 90505 high-nickel ternary cathode material, which was then used to make a battery.

[0034] Comparative Example 3 A Mg- and P-doped aluminosilicate coated material (Li1, P2) was prepared using the existing sol-gel method (using lithium nitrate, aluminum isopropoxide, and tetraethyl orthosilicate as raw materials, mixed in a Li:Al:Si molar ratio of 1.2:0.2:1.5, with anhydrous ethanol as solvent, simple mixing and dissolution at room temperature followed by rapid addition of a silicon source for hydrolysis, pH adjustment to 8-9 with dilute ammonia, aging at room temperature for 12 hours, drying at 80°C for 6 hours, sintering at 700°C in air for 3 hours, and finally, after conventional grinding and sieving, the target material was obtained). 1.2 Al 0.2 Si 0.3 O 1.5 ·1.2SiO2), modified the finished 90505 high-nickel ternary cathode material according to the application process of Example 1, and made it into a battery.

[0035] Comparative Example 4 Without adding any coating material, the finished 90505 high-nickel ternary cathode material is directly assembled into batteries.

[0036] Comparative Example 5 The novel aluminosilicate coating material of Example 1 was used, but prepared by a traditional solid-state sintering method (the raw material element stoichiometry was exactly the same as in Example 1, after dry ball milling for 3 hours, pre-sintering at 600°C for 3 hours, secondary coarse grinding, and final sintering at 900~1000°C in air for 6 hours, and finally grinding and sieving to obtain the target material) (replacing the sol-gel method of the present invention). The finished 90505 high-nickel ternary cathode material was then modified according to the application process of Example 1 to make a battery.

[0037] Comparative Example 6 Lithium, magnesium, aluminum, silicon, and phosphorus sources were dissolved in deionized water according to the proportions in Example 1 to prepare a mixed solution with a total concentration of 0.5 mol / L. After adjusting the pH to neutral, the solution was transferred to a high-pressure hydrothermal reactor and hydrothermally reacted at 180°C for 24 hours. After natural cooling, the solution was centrifuged, washed, and dried to obtain the coating material precursor. Subsequently, it was sintered under the same conditions as in Example 1. The finished 90505 high-nickel ternary cathode material was then modified according to the application process of Example 1 to fabricate a battery.

[0038] Comparative Example 7 The Al source in the raw materials of Example 1 was replaced with an equimolar amount of TiO2, and the coating material was prepared by the same sol-gel method. This material was then used to coat the cathode material under the same conditions to make a battery.

[0039] The cycle performance of lithium-ion batteries was tested using a Blue Electric electrochemical tester at a temperature of 25°C and a current density of 0.1C (0.1C = 210 mAg). -1 The charge / discharge voltage range is 4.3–2.0V, and the initial charge / discharge performance of the battery is tested. Cycle performance is then tested at 2.0–4.3V, 1C / 1C.

[0040] The results are shown in Table 1.

[0041] Table 1. Comparison of performance parameters between the examples and comparative examples

[0042] Test results show that the novel aluminosilicate coating materials prepared in Examples 1-3 of this invention have uniform particle size and excellent dispersibility, and the preparation energy consumption is significantly lower than that of the comparative examples. When used to modify cathode materials, they are significantly superior to the comparative examples in terms of specific capacity, pyrolysis oxygen temperature, cycle stability, and residual alkali reduction. Compared with Comparative Example 1 (ordinary aluminosilicate), the preparation energy consumption of the coating material of this invention is reduced by 25%, and the specific capacity of the modified cathode material is increased by 4.3%, the pyrolysis oxygen temperature is increased by 5.3%, and the residual alkali content is reduced by 37%. Compared with Comparative Example 5 (prepared by traditional solid-state sintering with the same composition), the coating material of this invention has more uniform particles, and the cycle retention rate of the modified cathode material is increased by 3.4%, and the residual alkali content is reduced by 10.5%. Compared with Comparative Example 6, when preparing coating materials by hydrothermal method, it is difficult to accurately control the reaction temperature, reaction time, and mixing uniformity, which easily leads to problems such as particle agglomeration, uneven coating layer, and weak interfacial bonding. Compared with Comparative Example 7, the cycle stability and capacity after replacing Al with Ti are significantly worse than those of Example 1 of this invention. The invention fully verifies the structural innovation and advanced preparation process of the novel aluminosilicate coating material, as well as its excellent effect in the modification of high-nickel ternary cathode materials.

[0043] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and substance defined by the claims of the present invention; and such modifications or substitutions are still within the scope defined by the claims of the present invention.

Claims

1. A method for preparing a high-nickel ternary cathode coating material, characterized in that, Includes the following steps: (1) Add lithium source, magnesium source, aluminum source and phosphorus source to deionized water, stir until completely dissolved, control the solution temperature at 50~60℃, add citric acid, stir for 30~60min to form a uniform metal ion complex solution; slowly add silicon source to the metal ion complex solution at a dropping rate of 1~2 drops / second, while stirring continuously. After the addition is complete, continue stirring for 1~2h, adjust the pH value of the solution to 3~4, keep warm at 30~40℃, and stir until a transparent sol is formed; the elemental molar ratio of lithium, magnesium, aluminum, silicon and phosphorus is Li:Mg:Al:Si:P=0.8-1.5:0.3-0.8:0.1-0.3:1.05-1.7:0.2-0.5; (2) Place the transparent sol in a constant temperature drying oven and keep it at 60~80℃ for 12~24h to allow the sol to slowly dehydrate and form a gel; take out the gel and age it at room temperature for 24~48h. (3) Place the aged gel in an oven and dry it at 100~120℃ for 4~6h to remove residual moisture and organic impurities; transfer the dried gel into an atmosphere muffle furnace, introduce air as a protective atmosphere, with an air flow rate of 50~80mL / min, heat it to 500~600℃ at a heating rate of 3~5℃ / min, keep it at that temperature for 3~5h, cool it to room temperature, grind it, and pass it through a 200~300 mesh sieve to obtain a novel aluminosilicate coated material.

2. The preparation method according to claim 1, characterized in that, The lithium source is selected from lithium carbonate or lithium nitrate, the magnesium source is selected from magnesium oxide or magnesium nitrate, the aluminum source is selected from aluminum oxide or aluminum isopropoxide, the silicon source is selected from tetraethyl orthosilicate or sodium silicate, and the phosphorus source is selected from ammonium dihydrogen phosphate or phosphoric acid.

3. The preparation method according to claim 1, characterized in that, The molar ratio of citric acid to all metal ions is 1.2~1.5:

1.

4. A high-nickel ternary cathode coating material, characterized in that, It is prepared by the preparation method according to any one of claims 1-3.

5. The high-nickel ternary cathode coating material according to claim 1, characterized in that, The chemical formula of the high-nickel ternary cathode coating material is Li. a Mg b Al c Si d P e O ζ ·nSiO2, where n is the degree of polymerization of silicon-oxygen tetrahedra, 1.0≤n≤1.5, 0.8≤a≤1.5, 0.3≤b≤0.8, 0.1≤c≤0.3, 0.05≤d≤0.2, 0.2≤e≤0.5, and ζ is the molar percentage of oxygen, ζ=(a+2b+3c+4d+5e) / 2.

6. The application of the high-nickel ternary cathode coating material as described in claim 4 or 5 in the modification of finished high-nickel ternary cathode materials.

7. The application according to claim 6, characterized in that, The application includes the following steps: (a) Raw material mixing: The finished high-nickel ternary cathode material and the high-nickel ternary cathode coating material are put into a ball mill at a mass ratio of 99.5:0.5~99.9:0.1, with agate balls as the grinding medium, a ball-to-material ratio of 20:1~30:1, a rotation speed of 200~300 r / min, and a ball milling time of 30~60 min to obtain a uniformly mixed powder; (b) Solid-state sintering: The mixed powder is placed in an atmosphere muffle furnace, and oxygen is introduced as a protective atmosphere at a flow rate of 50~100 mL / min. The temperature is raised to 350℃ at a heating rate of 5~10℃ / min, held for 2~4 hours, and then cooled to room temperature with the furnace to obtain the modified high-nickel ternary cathode material.

8. The preparation method according to claim 7, characterized in that, The finished high-nickel ternary cathode material is one of NCM811, NCM90505, and NCM955.

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