A method for preparing ternary high-nickel cathode material for use in portable power banks

Abstract

This invention provides a method for preparing a ternary high-nickel cathode material for mobile power banks. Utilizing the synergistic effect of multi-element doping, the method stabilizes the layered structure of the ternary cathode material, broadens the lithium-ion transport channels, enhances the M-O bond energy, reduces lattice oxygen generation during side reactions, decreases gas production, and improves the material's thermal stability. Furthermore, the ternary cathode material is wet-coated with phosphate, solid electrolyte, and lithium oxychloride oxide using an organic solvent. Based on the amount of residual alkali and lithium oxychloride oxide on the surface of the calcined ternary cathode material, the method determines whether to supplement a certain amount of lithium salt in the organic solvent to reduce lithium dissolution and excessive consumption of surface lithium. The coated material is then sintered at high temperature to prepare a high-nickel ternary cathode material with low residual alkali, excellent high-temperature storage performance, and superior thermal stability.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery cathode materials, and more particularly to a method for preparing a ternary high-nickel cathode material for use in portable power banks. Background Technology

[0002] Entering the 21st century, with the rapid development of the electronics industry, mobile electronic devices have been widely used. Mobile electronic devices are generally small in size, easy to carry and use, but their energy storage devices are generally small and non-removable. Therefore, the demand for mobile energy storage devices is increasing. As the core component of mobile energy storage devices, the performance of lithium-ion batteries directly affects the service life and safety of mobile energy storage devices. In addition, with the rapid development of mobile energy storage devices in my country, my country often needs to carry out ocean shipping to customers in India, Europe and the United States. The transportation cycle is about 10-30 days. The temperature of the containers can reach 60-80℃. Moreover, the operating conditions of mobile energy storage devices are generally poor, with the temperature range spanning -20-70℃. Therefore, there is a current demand for higher storage performance and thermal stability of lithium-ion batteries used in mobile energy storage devices. Ternary cathode materials have become the mainstream choice for cathode materials in lithium-ion batteries due to their high energy density and good cycle performance. However, with the continuous increase of nickel content, high-nickel ternary cathode materials (Nimol%≥80%) have poor storage performance and thermal stability at high temperatures, which limits the application of high-nickel ternary cathode materials in this field.

[0003] As the nickel content of high-nickel ternary cathode materials increases, their capacity also increases, resulting in higher energy per unit volume in lithium-ion batteries. However, the higher the nickel content, the higher the amount of Ni present when fully charged. 4+ The more ions, the better Ni 4+ The ion itself has strong oxidizing properties and is easily reduced to Ni. 2+ It releases lattice oxygen and easily catalyzes the decomposition of organic solvents (such as EC and DEC) in the electrolyte, accelerating electrolyte decomposition and generating gases (such as CO2) and heat, leading to battery expansion and thermal runaway. This situation is more likely to occur in high-temperature environments, resulting in poor gas generation capacity of the manufactured lithium-ion battery during high-temperature storage. To avoid this situation, it is generally necessary to improve the performance of ternary cathode materials through doping and coating modification processes.

[0004] For example, the invention patent with application number CN202111428230.4 uses a high-temperature solid-state reaction between a precursor and nano-Nb2O5 powder to generate Nb 5+Introducing niobium phosphate into high-nickel cathode materials and coating them with niobium phosphate using solid-phase coating to form a protective interface hinders the contact between the high-nickel cathode material and the electrolyte in lithium-ion batteries, reducing side reactions and improving the rate capability and cycle performance of the material. However, this method uses solid-phase coating, which makes the nano-niobium phosphate powder prone to agglomeration and uneven distribution on the cathode material surface. This increases the contact area between the cathode material and the electrolyte, leading to cathode material failure. Furthermore, this method, which uses a single Nb element doping and niobium phosphate coating scheme, has limited improvement on the high-temperature storage and thermal stability of high-nickel cathode materials.

[0005] The invention patent with application number CN202480000115.2 involves mixing a high-nickel cathode material precursor with lithium hydroxide and sintering it, then performing a wet coating with a salt solution containing Na and Li elements, and finally using atomic deposition equipment to coat the surface with metal oxides to improve the cycle and gas generation performance of the cathode material. However, the Na and Li salts used in this method significantly corrode the surface of the ternary cathode material, causing some defects and increasing side reactions. Furthermore, while atomic deposition equipment has good coating performance for surface materials, it has poor coating performance for internal materials. The operation is complex and costly, making mass production conversion difficult. Therefore, there is an urgent need to develop a high-nickel ternary cathode material for lithium-ion batteries used in mobile energy storage. This material should have good storage performance and thermal stability under high temperature conditions. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of the prior art by providing a method for preparing ternary high-nickel cathode materials for use in portable power banks.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention provides a method for preparing a ternary high-nickel cathode material for use in portable power banks, comprising the following steps:

[0009] S1. Doping: The precursor, lithium salt and additive M are mixed and stirred evenly, and the mixture is mixed by a high-speed mixer to obtain material H1 with no white spots on the surface; it is transferred into a mullite box, and the overall material thickness is controlled within 35±5mm; after one calcination, cooling and crushing, the material to be coated H2 is obtained.

[0010] S2, Coating: Add the material H2 to be coated into an organic solvent, mix and stir the phosphate, solid electrolyte and lithium oxyacid oxide, and add battery-grade lithium hydroxide micro powder to the organic solvent to supplement the lithium source based on the lithium content of the total residual alkali on the surface of the material H2 to be coated and the total amount of lithium source required by the lithium oxyacid contained in the coating agent.

[0011] The amount of lithium hydroxide battery-grade micro powder added for:

[0012] ;

[0013] like If the value is ≥0, then no lithium replenishment is required;

[0014] like If the value is less than 0, then add lithium hydroxide according to the required lithium content.

[0015] S3. The material after adding lithium hydroxide battery-grade micro powder is stirred at high speed, the temperature is controlled at 50-70℃, the magnetic stirrer speed is controlled at 400±50 rpm, and after the organic solvent is dried, a ternary cathode material H3 containing phosphate, solid electrolyte and lithium oxychloride oxide uniformly coated is obtained.

[0016] S4. The uniformly coated ternary cathode material H3 is subjected to a second calcination, batch mixing, sieving, iron removal, and then packaged, and relevant performance tests are conducted.

[0017] Furthermore, in S1, the D50 of the precursor is in the range of 8 μm to 12 μm;

[0018] The additive M is either nano-zirconia or nano-alumina, or at least one of cobalt tetroxide, cobalt trioxide, lanthanum oxide, magnesium oxide, yttrium oxide, cerium oxide, titanium oxide, tungsten oxide, molybdenum oxide, chromium oxide, zirconium oxide, strontium oxide, and aluminum oxide.

[0019] By weight, the total content of the main elements in the additive M is 10,000 ppm to 16,000 ppm, wherein the total content of Al and Zr elements in the additive M is ≥10,000 ppm.

[0020] Furthermore, the original crystal size of the additive M is ≤100nm.

[0021] Furthermore, in S2,

[0022] The organic solvent is one or more of ethanol, isopropanol, and n-propanol;

[0023] The phosphate is one or more of Ca3(PO4)2, Zr3(PO4)4, Ti3(PO4)4, Na3PO4, Zn3(PO4)2, Mg3(PO4)2, AlPO4, FePO4, and Li3PO4;

[0024] The solid electrolyte is one of LLZO, LATP, LAGP, LPS, LGPS, and Li2S-P2S5, and the oxoacid lithium salt oxide is one or two of silicon dioxide, tungsten oxide, titanium oxide, boric acid, cobalt tetroxide, cobalt trioxide, and niobium pentoxide.

[0025] Furthermore, the oxyacid lithium salt oxide is added according to the content of non-oxygen elements, with an addition amount of ≥5000ppm by weight.

[0026] The content of metal elements in the phosphate and the content of metal elements in the solid electrolyte are ≥10000ppm.

[0027] Furthermore, in S1, the first calcination specifically involves:

[0028] The mullite box containing material H1 is placed in a box furnace, and liquid oxygen is introduced to ensure that the oxygen concentration inside the box is ≥98±0.5%. The temperature is increased at a rate of 2-3℃ / min and held at 500℃ for 7-10 hours to ensure that the moisture in the precursor and lithium source is fully evaporated, promoting the full diffusion of the precursor, lithium source and dopant, and ensuring the normal occurrence of subsequent reactions. After the holding time, the furnace is heated to 700-880℃ at a rate of 5-8℃ / min and held for 12-14 hours. After the holding time, the furnace is closed and cooled down at a natural cooling rate. During the cooling process, the oxygen concentration is kept consistent with that during constant temperature sintering. When the furnace temperature is cooled to room temperature, the furnace door is opened and the material is taken out to obtain the doped material that has been sintered in one step.

[0029] Further, in S1, the crushing specifically involves: coarsely crushing the doped material after one-time sintering using a double-layer roller mill, controlling the gap between the upper rollers at 10±3mm and the gap between the lower rollers at 3.5±1mm to prevent over-crushing of the material, which could lead to surface structure breakage or cracking; after crushing, the material is ball-milled, using a ball mill to grind it, mixing 5mm and 10mm zirconium balls at a ratio of 1:1, controlling the weight ratio of zirconium balls to material at 1:3, controlling the ball mill speed at 200 rpm, and controlling the grinding time within 120±10 minutes. After mixing, the material to be coated, H2, is obtained, and 5g of H2 material is taken... Pour ± 0.0005 g of solution into a 100 mL beaker and add a stir bar. Accurately measure 50 mL of deionized water using a 50 mL graduated cylinder and slowly add it to the beaker. Place the beaker on a magnetic stirrer, set the stirring speed to 500 rpm, and the stirring time to 30 min. After stirring, filter the solution into a 100 mL volumetric flask, dilute to volume, and shake well to obtain the sample solution. Use a potentiometric titrator to test the residual alkali content on the surface of the sample solution, and calculate the content based on the lithium oxyacid salt to be coated. The value determines whether lithium replenishment is needed.

[0030] Further, the uniformly coated ternary cathode material H3 is transferred into a mullite box, with the overall material thickness controlled within 35±5mm. It is placed in a box furnace, and liquid oxygen is introduced to ensure that the oxygen concentration inside the box is ≥98±0.5%. The temperature is increased at a rate of 2-3℃ / min and held at 300℃ for 2-4 hours to ensure that the residual alkali on the surface, the added lithium source, and the oxychloride lithium oxide are in full contact. After the holding period, the furnace is heated to 600±50℃ at a rate of 5-8℃ / min and held for 8-12 hours. After the holding period, the furnace is closed and cooled down naturally. After the cooling is complete, the finished ternary cathode material H4 is obtained.

[0031] Furthermore, the general formula of the ternary cathode material H4 is LiNi. x Co y T Z MO2, where 0.8≤X≤0.95, 0.01≤Y≤0.18, and 0.01≤Z≤0.18.

[0032] The beneficial effects of this invention are as follows: By rapidly mixing the ternary cathode material precursor, lithium source, and nano-doped additives during the mixing stage of ternary cathode material production, the synergistic effect of multi-element doping is utilized to stabilize the stability of the layered structure of the ternary cathode material, broaden the lithium-ion transport channels, enhance the bond energy of MO, reduce the generation of lattice oxygen during side reactions, reduce gas production in the material, and improve the thermal stability of the material. In addition, the ternary cathode material is wet-coated with phosphate, solid electrolyte, and lithium oxychloride oxide using an organic solvent. Based on the amount of residual alkali on the surface of the ternary cathode material and the amount of lithium oxychloride oxide, it is determined whether to add a certain amount of lithium salt in the organic solvent to reduce lithium dissolution and excessive consumption of surface lithium in the ternary cathode material. The coated material is then sintered at high temperature to prepare a high-nickel ternary cathode material with low residual alkali on the surface, excellent high-temperature storage performance, and excellent thermal stability. Attached Figure Description

[0033] Figure 1 A flowchart illustrating a method for preparing a ternary high-nickel cathode material for use in portable power banks;

[0034] Figure 2 XRD patterns for the embodiments and comparative examples;

[0035] Figure 3 DSC diagrams for the embodiments and comparative examples;

[0036] Figure 4 This is a SEM image of Example 1;

[0037] Figure 5 This is a SEM image of Example 2;

[0038] Figure 6 This is the SEM image of Comparative Example 1;

[0039] Figure 7 This is the SEM image of Comparative Example 2. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0041] A method for preparing a ternary high-nickel cathode material for use in portable power banks includes the following steps:

[0042] S1. Doping: The precursor, lithium salt and additive M are mixed and stirred evenly, and the mixture is mixed by a mixer to obtain material H1 with no white spots on the surface; it is transferred into a mullite box, and the overall material thickness is controlled within 35±5mm; after one calcination, cooling and crushing, the material to be coated H2 is obtained.

[0043] S2, Coating: Add the material H2 to be coated into an organic solvent, mix and stir the phosphate, solid electrolyte and lithium oxyacid oxide, and add battery-grade lithium hydroxide micro powder to the organic solvent to supplement the lithium source based on the lithium content of the total residual alkali on the surface of the material H2 to be coated and the total amount of lithium source required by the lithium oxyacid contained in the coating agent.

[0044] The amount of lithium hydroxide battery-grade micro powder added for:

[0045] ;

[0046] like If the value is ≥0, then no lithium replenishment is required;

[0047] like If the value is less than 0, then add lithium hydroxide according to the required lithium content.

[0048] S3. The material after adding lithium hydroxide battery-grade micro powder is stirred at high speed, the temperature is controlled at 50-70℃, the magnetic stirrer speed is controlled at 400±50 rpm, and after the organic solvent is dried, a ternary cathode material H3 containing phosphate, solid electrolyte and lithium oxychloride oxide uniformly coated is obtained.

[0049] S4. The uniformly coated ternary cathode material H3 is subjected to a second calcination, batch mixing, sieving, iron removal, and then packaged, and relevant performance tests are conducted.

[0050] In S1, the D50 of the precursor is in the range of 8 μm to 12 μm;

[0051] The additive M is either nano-zirconia or nano-alumina, or at least one of cobalt tetroxide, cobalt trioxide, lanthanum oxide, magnesium oxide, yttrium oxide, cerium oxide, titanium oxide, tungsten oxide, molybdenum oxide, chromium oxide, zirconium oxide, strontium oxide, and aluminum oxide.

[0052] By weight, the total content of the main elements in the additive M is 10,000 ppm to 16,000 ppm, wherein the total content of Al and Zr elements in the additive M is ≥10,000 ppm.

[0053] The original crystal size of the additive M is ≤100nm.

[0054] In S2,

[0055] The organic solvent is one or more of ethanol, isopropanol, and n-propanol;

[0056] The phosphate is one or more of Ca3(PO4)2, Zr3(PO4)4, Ti3(PO4)4, Na3PO4, Zn3(PO4)2, Mg3(PO4)2, AlPO4, FePO4, and Li3PO4;

[0057] The solid electrolyte is one of LLZO, LATP, LAGP, LPS, LGPS, and Li2S-P2S5, and the oxoacid lithium salt oxide is one or two of silicon dioxide, tungsten oxide, titanium oxide, boric acid, cobalt tetroxide, cobalt trioxide, and niobium pentoxide.

[0058] By weight, lithium oxyacid oxides are added according to the content of non-oxygen elements, with an addition amount ≥5000ppm;

[0059] The content of metal elements in the phosphate and the content of metal elements in the solid electrolyte are ≥10000ppm.

[0060] In S1, the first calcination specifically involves:

[0061] The mullite box containing material H1 is placed in a box furnace, and liquid oxygen is introduced to ensure that the oxygen concentration inside the box is ≥98±0.5%. The temperature is increased at a rate of 2-3℃ / min and held at 500℃ for 7-10 hours to ensure that the moisture in the precursor and lithium source is fully evaporated, promoting the full diffusion of the precursor, lithium source and dopant, and ensuring the normal occurrence of subsequent reactions. After the holding time, the furnace is heated to 700-880℃ at a rate of 5-8℃ / min and held for 12-14 hours. After the holding time, the furnace is closed and cooled down at a natural cooling rate. During the cooling process, the oxygen concentration is kept consistent with that during constant temperature sintering. When the furnace temperature is cooled to room temperature, the furnace door is opened and the material is taken out to obtain the doped material that has been sintered in one step.

[0062] In S1, the crushing process specifically involves: coarsely crushing the doped material after one-time sintering using a double-layer roller mill, controlling the gap between the upper rollers at 10±3mm and the gap between the lower rollers at 3.5±1mm to prevent over-crushing, which could lead to surface structural breakage or cracking; after crushing, the material is ball-milled, using a mixture of 5mm and 10mm zirconium balls at a 1:1 ratio, with the weight ratio of zirconium balls to material controlled at 1:3, the ball mill speed controlled at 200 rpm, and the crushing time controlled within 120±10 minutes. After mixing, the material to be coated, H2, is obtained. 5g of H2 material is then taken... Pour ± 0.0005 g of solution into a 100 mL beaker and add a stir bar. Accurately measure 50 mL of deionized water using a 50 mL graduated cylinder and slowly add it to the beaker. Place the beaker on a magnetic stirrer, set the stirring speed to 500 rpm, and the stirring time to 30 min. After stirring, filter the solution into a 100 mL volumetric flask, dilute to volume, and shake well to obtain the sample solution. Use a potentiometric titrator to test the residual alkali content on the surface of the sample solution, and calculate the content based on the lithium oxyacid salt to be coated. The value determines whether lithium replenishment is needed.

[0063] The uniformly coated ternary cathode material H3 is transferred into a mullite box, with the overall material thickness controlled within 35±5mm. It is placed in a box furnace, and liquid oxygen is introduced to ensure that the oxygen concentration in the box is ≥98±0.5%. The temperature is increased at a rate of 2-3℃ / min and held at 300℃ for 2-4 hours to ensure that the residual alkali on the surface, the added lithium source, and the oxychloride lithium oxide are in full contact. After the holding time, the furnace is heated to 600±50℃ at a rate of 5-8℃ / min and held for 8-12 hours. After the holding time, the furnace is turned off and cooled down at a natural cooling rate. After the cooling is complete, the finished ternary cathode material H4 is obtained.

[0064] The general formula of the ternary cathode material H4 is LiNi. x Co y T ZMO2, where 0.8≤X≤0.95, 0.01≤Y≤0.18, and 0.01≤Z≤0.18.

[0065] Example 1

[0066] Please see Figure 2 , Figure 3 and Figure 4 A method for preparing a ternary high-nickel cathode material for mobile power banks, comprising the following parts by weight of raw materials: one part of a semi-continuous precursor with a D50 of 10 μm;

[0067] M(OH)2, Nimol%:Comol%:Mnmol=83:12:05, D50=10.0μm, using lithium hydroxide (LiOH·H2O) as the lithium source, with Li / M=1.04 (lithium ratio) and additives zirconium oxide (4000ppm), aluminum hydroxide (6000ppm), and yttrium oxide (1000ppm). The materials were mixed using a high-speed mixer at 300 r / min for 40 min. After the materials were mixed, they were placed in a box furnace for sintering. The temperature was increased at 3℃ / min to 500℃ and held for 8 h. After holding, the temperature was increased at 5℃ / min to 780℃ and held for 12.5 h. After cooling, the materials were taken out to obtain the doped material that was sintered in one step.

[0068] The doped material, after being sintered in one step, is coarsely crushed using a double-layer roller mill, with the upper roller gap controlled at 10mm and the lower roller gap at 3mm. After crushing, the material is loaded into a planetary ball mill for grinding. Zirconium balls with diameters of 5mm and 10mm are mixed at a mass ratio of 1:1. The mixed zirconium balls are then added to the ball mill jar at a mass ratio of 1:3 with the material to be crushed. The ball mill speed is set to 200r / min, and the material is ground for 120min to obtain uniformly distributed particles of the material to be coated, H2. 5g of H2 is weighed and added to a beaker, and a stirring magnet is placed inside. 50g of H2 is accurately measured using a 50mL graduated cylinder. Slowly add mL of distilled water or boiled deionized water to a beaker, place the beaker on a magnetic stirrer, set the stirring speed to 500 rpm, and the stirring time to 30 min. After stirring, filter into a 100 mL volumetric flask, make up to volume, shake well, and then use a potentiometric titrator to detect the alkalinity of the solution. The LiOH content is 6531 ppm and the Li2CO3 content is 4621 ppm.

[0069] The lithium oxoacid coating material selected in this experiment is Co3O4. Based on a Co content of 5000 ppm, and since the corresponding lithium oxoacid is LiCoO2, the total lithium content required for Co3O4 with a Co content of 5000 ppm is 5000 / 58.933*6.94 = 588.8 ppm. According to the surface residual alkali measured in H2, the total lithium content used is 6531 / (6.94+16+1)*6.94+4 621 / (6.94*2+12+16*3)*2*6.94=2761.5ppm. According to the θ formula, θ=2761.5 / 2-588.8*1.4=556.4>0. Therefore, no additional lithium is needed in this experiment. The material is placed on a constant temperature magnetic stirring table for heating. The constant temperature is controlled at 70℃, and the magnetic stirring speed is set to 400r / min. After the organic solvent is evaporated, the ternary cathode material H3 with uniform surface coating is obtained.

[0070] The ternary cathode material H3 was transferred into a mullite crucible, with the overall material thickness controlled within 35±5mm. It was then placed in a box furnace, and liquid oxygen was introduced to ensure an oxygen concentration ≥98±0.5% within the crucible. The temperature was increased at a rate of 2-3℃ / min and held at 300℃ for 4 hours. After this holding period, the furnace was heated to 600℃ at a rate of 5-8℃ / min and held for 10 hours. After this holding period, the furnace was shut off, and the material was allowed to cool naturally. After cooling, the finished LiNi product was obtained. 83 Co 12 Material 1 of Mn05O2.

[0071] Example 2

[0072] Please see Figure 2 , Figure 3 and Figure 5 A method for preparing a ternary high-nickel cathode material for mobile power banks, comprising the following parts by weight of raw materials: one part of a semi-continuous precursor with a D50 of 10 μm;

[0073] The semi-continuous precursor M(OH)2, with Nimol%:Comol%:Mnmol=90:05:05 and D50=10.0μm, uses lithium hydroxide (LiOH·H2O) as the lithium source. The mixture is prepared with additives: Li / M=1.04 (lithium ratio), zirconium oxide (5000ppm), aluminum hydroxide (5000ppm), and yttrium oxide (1000ppm). A high-speed mixer is used for batching at 300r / min for 40min. After batching, the material is placed in a box furnace for sintering. The temperature is increased at 3℃ / min, held at 500℃ for 8h, and then increased to 760℃ at a rate of 5℃ / min for 12.5h. After cooling, the material is removed to obtain the material from the first sintering process.

[0074] The material from the first sintering process was coarsely crushed using a double-layer roller mill, with the upper roller gap controlled at 10mm and the lower roller gap at 3mm. After crushing, the material was loaded into a planetary ball mill for grinding. Zirconium balls with diameters of 5mm and 10mm were mixed at a mass ratio of 1:1. The mixed zirconium balls and the material to be crushed were added to the ball mill jar at a mass ratio of 1:3. The ball mill speed was set to 200r / min, and the material was ground for 120min to obtain uniformly distributed particles of the material to be coated, H2. 5g of H2 was weighed and added to a beaker, and a stirring magnet was placed inside. 50g of H2 was accurately measured using a 50mL graduated cylinder. Slowly add mL of distilled water or boiled deionized water to a beaker, place the beaker on a magnetic stirrer, set the stirring speed to 500 rpm, and the stirring time to 30 min. After stirring, filter into a 100 mL volumetric flask, make up to volume, shake well, and then use a potentiometric titrator to detect the alkalinity of the solution. The LiOH content is 8571 ppm and the Li2CO3 content is 4937 ppm.

[0075] The lithium oxyacid coating material selected in this experiment is Co3O4. Based on the Co content of 5000 ppm, and the corresponding lithium oxyacid of Co3O4 being LiCoO2, the total lithium content required for Co3O4 with a Co content of 5000 ppm is 5000 / 58.933*6.94 = 588.8 ppm. According to the surface residual alkali measured in H2, the lithium content used is 8571 / (6.94+16+1)*6.94+4931 / (6.94*2+12+16*3)*2*6.94 = 3412 ppm. formula, =3412.2 / 2-588.8*1.4=881.8>0, so no additional lithium is needed in this experiment. The material is placed on a constant temperature magnetic stirring table for heating. The constant temperature is controlled at 70℃ and the magnetic stirring speed is set to 400r / min. After the organic solvent is evaporated, the ternary cathode material H3 with uniform surface coating is obtained.

[0076] The material to be coated, H3, was added to an alcohol solution, along with 2000 ppm aluminum phosphate, 10000 ppm LATP powder with Ti content, and 5000 ppm Co3O4. Lithium was then added. The material was placed on a constant-temperature magnetic stirring table and heated. The constant temperature was controlled at 70°C, and the magnetic stirring speed was set to 400 r / min. After the organic solvent evaporated, a ternary cathode material H4 with a uniform surface coating was obtained.

[0077] The ternary cathode material H4 was transferred into a mullite crucible, with the overall material thickness controlled within 35±5mm. It was then placed in a box furnace, and liquid oxygen was introduced to ensure an oxygen concentration ≥98±0.5% within the crucible. The temperature was increased at a rate of 2-3℃ / min and held at 300℃ for 4 hours. After this holding period, the furnace was heated to 600℃ at a rate of 5-8℃ / min and held for 10 hours. After this holding period, the furnace was shut off, and the material was allowed to cool naturally. After cooling, the finished LiNi product was obtained. 90 Co 05 Mn 05 Material 2 of O2.

[0078] Comparative Example 1:

[0079] Please see Figure 2 , Figure 3 and Figure 6 The semi-continuous precursor M(OH)2, with Nimol%:Comol%:Mnmol=83:12:05 and D50=10.0μm, uses lithium hydroxide (LiOH·H2O) as the lithium source. The mixture is prepared with Li / M=1.04 (lithium ratio) and additives zirconium oxide (2500ppm) and aluminum hydroxide (1500ppm). The mixture is prepared using a high-speed mixer at 300r / min for 40min. After preparation, the material is placed in a box furnace for sintering. The temperature is increased at 3℃ / min to 500℃ and held for 8h. After holding, the temperature is increased at 5℃ / min to 780℃ and held for 12.5h. After cooling, the material is removed to obtain the material from the first sintering process.

[0080] The material from the first sintering process was coarsely crushed using a double-layer roller mill, with the upper roller gap controlled at 10mm and the lower roller gap at 3mm. After crushing, the material was loaded into a planetary ball mill for ball milling. Zirconium balls with diameters of 5mm and 10mm were mixed at a mass ratio of 1:1. The mixed zirconium balls and the material to be crushed were added to the ball mill tank at a mass ratio of 1:3. The ball mill speed was set at 200r / min, and the material was crushed for 120min to obtain a uniformly distributed material to be coated.

[0081] Add the material to be coated into an alcohol solution, add 2000 ppm of alumina and 1000 ppm of Ti equivalent, place the material on a constant temperature magnetic stirring table for heating, control the constant temperature at 70℃, and set the magnetic stirring speed to 400 r / min. After the organic solvent evaporates, a material with a uniform surface coating is obtained for secondary high-temperature sintering.

[0082] The material to be uniformly coated for secondary high-temperature sintering was transferred to a mullite sagger, with the overall material thickness controlled within 35±5mm. It was placed in a box furnace, and liquid oxygen was introduced to ensure an oxygen concentration ≥98±0.5%. The temperature was increased at a rate of 2-3℃ / min and held at 300℃ for 4 hours. After holding, the furnace was heated to 600℃ at a rate of 5-8℃ / min and held for 10 hours. After holding, the furnace was shut off and cooled naturally. After cooling, the comparative finished product, LiNi, was obtained. 83 Co 12 Mn 05 Comparison sample 1 for O2;

[0083] Comparative Example 2:

[0084] Please see Figure 2 , Figure 3 and Figure 7 The semi-continuous precursor M(OH)2, with Nimol%:Comol%:Mnmol=90:05:05 and D50=10.0μm, uses lithium hydroxide (LiOH·H2O) as the lithium source. The mixture is prepared with Li / M=1.04 (lithium ratio) and additives zirconium oxide (2500ppm) and aluminum hydroxide (1500ppm). The mixture is prepared using a high-speed mixer at 300r / min for 40min. After preparation, the material is placed in a box furnace for sintering. The temperature is increased at 3℃ / min to 500℃ and held for 8h. After holding, the temperature is increased at 5℃ / min to 780℃ and held for 12.5h. After cooling, the material is removed to obtain the material from the first sintering process.

[0085] The material from the first sintering process was coarsely crushed using a double-layer roller mill, with the upper roller gap controlled at 10mm and the lower roller gap at 3mm. After crushing, the material was loaded into a planetary ball mill for ball milling. Zirconium balls with diameters of 5mm and 10mm were mixed at a mass ratio of 1:1. The mixed zirconium balls and the material to be crushed were added to the ball mill tank at a mass ratio of 1:3. The ball mill speed was set at 200r / min, and the material was crushed for 120min to obtain a uniformly distributed material to be coated.

[0086] Add the material to be coated into an alcohol solution, add 2000 ppm of alumina and 1000 ppm of Ti equivalent, place the material on a constant temperature magnetic stirring table for heating, control the constant temperature at 70℃, and set the magnetic stirring speed to 400 r / min. After the organic solvent evaporates, a material with a uniform surface coating is obtained for secondary high-temperature sintering.

[0087] The material to be sintered at high temperature for a second time, with its surface evenly coated, is transferred into a mullite sagger, with the overall material thickness controlled within 35±5mm. It is then placed in a box furnace, and liquid oxygen is introduced to ensure an oxygen concentration ≥98±0.5% within the furnace. The temperature is increased at a rate of 2-3℃ / min and held at 300℃ for 4 hours. After this holding period, the furnace is heated to 600℃ at a rate of 5-8℃ / min and held for 10 hours. After this holding period, the furnace is shut off and cooled naturally. After cooling, the comparative product LiNi is obtained. 90 Co 05 Mn 05 Comparison sample 2 for O2.

[0088] The above samples were homogenized according to the mass ratio of positive electrode material: conductive agent: binder of 92:5:3. The conductive agent was conductive graphite SP, and the binder was polyvinylidene fluoride (PVDF-Soway 5130). The electrode compaction density was controlled at 3.45±0.05g / cm3. After the above materials were made into electrodes, the electrodes were made into 3.0Ah full-electrode sheets according to the winding process and the full-electrode performance was tested. The full-electrode sheets charged to 4.3V (with 50% mass of full-electrode electrolyte) were tested using differential scanning calorimetry (DSC).

[0089] The specific data is as follows:

[0090] Table 1. All-electric data for the embodiments and comparative examples.

[0091]

[0092] Table 2 Gas production data for the examples and comparative examples

[0093]

[0094] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be defined by the appended claims.

Claims

1. A method for preparing a ternary high-nickel positive electrode material applied to a mobile power bank, characterized in that, The method comprises the following steps: S1, doping: the precursor, lithium salt and additive M are mixed and stirred uniformly, and the material H1 without white spots on the surface is obtained by mixing with a mixer; the material H1 is transferred into a mullite box, and the thickness of the whole material is controlled to be within 35±5 mm; after one-time calcination, cooling and crushing, the material H2 to be coated is obtained; S2, coating: the material H2 to be coated is added into an organic solvent, the phosphate, the solid-state electrolyte and the oxide corresponding to the oxyacid lithium salt are mixed and stirred, and the lithium source is supplemented by adding battery-grade lithium hydroxide powder into the organic solvent according to the lithium content contained in the total amount of residual alkali on the surface of the material H2 to be coated and the total amount of lithium source required in the coating agent; The amount of the battery grade lithium hydroxide fine powder added Is: ； If ≥ 0, no lithium supplement is needed; If If < 0, then add lithium hydroxide according to the lithium hydroxide content corresponding to the required lithium content; S3, the material added with the battery-grade lithium hydroxide powder is stirred at high speed, the temperature is controlled to be 50-70 DEG C, the rotating speed of the magnetic stirrer is controlled to be 400±50 r / min, and the organic solvent is dried to obtain the ternary positive electrode material H3 uniformly coated with the phosphate, the solid-state electrolyte and the oxide corresponding to the oxyacid lithium salt; S4, the ternary positive electrode material H3 uniformly coated is subjected to second calcination, batch mixing, screening and iron removal, and then is packaged; In the S1, the D50 of the precursor is in the range of 8 μm to 12 μm; The additive M is at least one of zirconium oxide, aluminum hydroxide, three cobalt oxide, two cobalt oxide, lanthanum oxide, magnesium oxide, yttrium oxide, cerium oxide, titanium oxide, tungsten oxide, molybdenum oxide, chromium oxide and strontium oxide; The total amount of Al and Zr elements contained in the additive M is ≥10000 ppm in terms of weight ratio; The original crystal size of the additive M is ≤100 nm; In the S2, The organic solvent is one or more of ethanol, isopropyl alcohol and n-propanol; The phosphate is one or more of Ca3 (PO4) 2, Zr3 (PO4) 4, Ti3 (PO4) 4, Na3PO4, Zn3 (PO4) 2, Mg3 (PO4) 2, AlPO4, FePO4 and Li3PO4; The solid-state electrolyte is one of LLZO, LATP, LAGP, LPS, LGPS and Li2S-P2S5, and the oxide corresponding to the oxyacid lithium salt is one or two of silicon dioxide, tungsten oxide, titanium oxide, boric acid, three cobalt oxide, two cobalt oxide and two niobium oxide.

2. The preparation method of the ternary high-nickel positive electrode material applied to the mobile power bank according to claim 1, characterized in that: The oxide corresponding to the oxyacid lithium salt is added according to the content of non-oxygen elements, and the addition amount is ≥5000 ppm in terms of weight ratio; The content of metal elements in the phosphate and the content of metal elements in the solid-state electrolyte are ≥10000 ppm.

3. The preparation method of the three-element high-nickel positive electrode material applied to the mobile power bank according to claim 2, characterized in that: In the S1, the first calcination is specifically: The mullite box loaded with the material H1 is placed in the box furnace, liquid oxygen is introduced to ensure that the oxygen concentration in the box is ≥98±0.5%, the temperature is raised at a speed of 2-3 ℃ / min, and the temperature is kept at 500 ℃ for 7-10 h to ensure that the moisture in the precursor and the lithium source is fully volatilized, the precursor, the lithium source and the dopant are fully diffused, and the subsequent reaction is ensured to occur normally; after the heat preservation is completed, the kiln is heated to 700-880 ℃ at a speed of 5-8 ℃ / min, and the temperature is kept for 12-14 h; after the heat preservation is completed, the kiln is closed and cooled at a natural cooling speed; the oxygen concentration is kept consistent during the cooling process; when the temperature of the kiln is cooled to room temperature, the door of the kiln is opened, and the material is taken out to obtain the doped material after the first sintering.

4. The preparation method of the three-element high-nickel positive electrode material applied to the mobile power bank according to claim 1, characterized in that: In the S1, the crushing specifically refers to: the doped material after the first sintering is coarsely broken by a double-layer roller machine, the gap between the upper rollers is controlled at 10±3 mm, and the gap between the lower rollers is controlled at 3.5±1 mm, so as to prevent the material from being excessively crushed, resulting in the surface structure being broken or cracks being generated; after the crushing, the material is ball-milled by a ball mill, zirconium balls of 5 mm and 10 mm are mixed, the mixing ratio is 1:1, the weight ratio of the zirconium balls to the material is controlled at 1:3, the rotating speed of the ball mill is controlled at 200 revolutions / min, the crushing time is controlled within 120±10 min, and after the mixing is completed, the material H2 to be coated is obtained; 5 g±0.0005 g of the H2 material is taken, poured into a 100 mL beaker, and a stirring rod is put in, 50 mL of deionized water is accurately measured by a 50 mL measuring cylinder, and added into the beaker, the beaker is placed on a magnetic stirrer, the stirring speed is set at 500 revolutions / min, and the stirring time is 30 min; after the stirring is completed, filtration is performed into a 100 mL volumetric flask, the volume is fixed, and the sample solution is obtained; the residual alkali content on the surface of the sample solution is tested by using a potential titrator, and the lithium supplement value is calculated according to the lithium oxide salt content to be coated, so as to determine whether lithium supplement is needed. value, determine whether lithium supplement is needed.

5. The preparation method of the three-element high-nickel positive electrode material applied to the mobile power bank according to claim 1, characterized in that: In the S4, the second calcination is specifically as follows: the uniformly coated ternary positive electrode material H3 is transferred into a mullite box, the thickness of the whole material is controlled to be within 35±5 mm, the mullite box is placed in a box furnace, liquid oxygen is introduced to ensure that the oxygen concentration in the box is ≥98±0.5%, the temperature is raised at a speed of 2-3 ℃ / min, and the temperature is kept at 300 ℃ for 2-4 h to ensure that the surface residual alkali, the added lithium source and the oxide corresponding to the lithium oxide salt are fully contacted; after the heat preservation is completed, the kiln is heated to 600±50 ℃ at a speed of 5-8 ℃ / min, and the temperature is kept for 8-12 h; after the heat preservation is completed, the kiln is closed and cooled at a natural cooling speed; after the cooling is completed, the finished product ternary positive electrode material H4 is obtained.

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