High-voltage high-nickel positive electrode material and preparation method and application thereof

Abstract

The application provides a high-voltage high-nickel positive electrode material, comprising: a substrate; a coating layer arranged on the surface of the substrate; the coating layer comprises: a spinel structure compound and a fast ion conductor phase compound; the specific surface area of the high-voltage high-nickel positive electrode material is 0.2-1.5 m 2 / g, and D50 is 2.0-18.0 mu m. In the application, the spinel phase is more stable than the layered material structure of the relative phase at high voltage, can improve the thermal stability and high-voltage overshoot resistance of the positive electrode material, that is, the high-voltage characteristics; the fast ion conductor can improve the rate of lithium ion extraction and embedding, reduce the internal resistance of the battery system, and improve the energy density of the material. The application further provides a preparation method and application of the high-voltage high-nickel positive electrode material.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery material technology, and particularly relates to a high-voltage, high-nickel cathode material, its preparation method and application, specifically a method for preparing a coated high-voltage, high-nickel cathode material. Background Technology

[0002] In new energy vehicles, battery costs account for a significant portion of the overall cost. With increasing consumer demand for longer driving ranges, improving battery energy density while reducing the cost of ternary cathode materials has become a key focus for battery manufacturers. Currently, the main high-voltage cathode material is lithium cobalt oxide, which, while possessing good rate performance and cycle life, suffers from poor overcharge resistance. Ternary cathode materials, on the other hand, offer advantages such as overcharge resistance, high capacity, and low cost, making them highly promising for high-voltage performance development. However, the maximum charging cut-off voltage of ternary cathode materials is currently only 4.3V; directly increasing this voltage would degrade cycle performance.

[0003] Existing technology discloses a method of coating a metal-doped titanium dioxide film onto the surface of a cathode material using a sol-gel method; then drying and sintering at a certain temperature to form a lithium-ion battery cathode material coated with metal ion-doped titanium dioxide; it uses an organic titanium source and β-diketone stabilizers as solvents, and organic matter generally has a certain degree of toxicity to the human body; in addition, the sol-gel process requires a long time, several days or weeks; moreover, there are a large number of micropores in the gel, and many gases and organic matter will escape during the drying process, and shrinkage will occur, which will easily form precipitation and make the coating uneven.

[0004] In addition, the method of preparing coated cathode materials by directly mixing lithium source, nickel cobalt manganese hydroxide and the metal oxide or other compound to be coated by solid-state sintering and sintering at high temperature has the disadvantage of uneven dispersion of additives during the preparation process, resulting in large differences in the material structure after sintering and making it extremely difficult to form a uniform coating layer on the material surface. Furthermore, the difficulty and high cost of preparing nanomaterial additives are also disadvantages of the solid-state sintering method. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a high-voltage, high-nickel cathode material, its preparation method, and its application. The high-voltage, high-nickel cathode material provided by this invention can suppress the problems caused by voltage rise and has good structural stability.

[0006] This invention provides a high-voltage, high-nickel cathode material, comprising:

[0007] Matrix;

[0008] A coating layer disposed on the surface of the substrate;

[0009] The coating layer comprises: a spinel-structured compound and a fast-ion conductor phase compound;

[0010] The specific surface area of ​​the high-voltage, high-nickel cathode material is 0.2–1.5 m². 2 / g, the D50 of the high-voltage high-nickel cathode material is 2.0~18.0μm.

[0011] Preferably, the composition formula of the matrix is:

[0012] LiNi x M (1-x) O2 Formula I;

[0013] In Equation I, 0.6 ≤ x < 1,

[0014] M is selected from at least two of the following: Co, Mn, B, Mg, Al, Zr, Sr, Mo, Ti, and P.

[0015] Preferably, the spinel-structured compound includes CoAl2O4 and Co2TiO4;

[0016] The fast ion conductor phase compound is Li3PO4;

[0017] This invention provides a method for preparing the high-voltage, high-nickel cathode material described in the above technical solution, comprising:

[0018] Solution A, solution B and solution M were mixed and coprecipitated to obtain the coated product;

[0019] The coated product and lithium source are mixed and then sintered to obtain a high-voltage, high-nickel cathode material.

[0020] Solution A is a mixed solution of aluminum salt and titanium salt;

[0021] Solution B is a phosphate solution;

[0022] The solution M is a solution containing a high-nickel cathode precursor.

[0023] Preferably, the aluminum salt is selected from aluminum nitrate and / or sodium aluminate;

[0024] The titanium salt is selected from ammonium fluorotitanate and / or titanium oxysulfate;

[0025] The ratio of aluminum salt to titanium salt is such that the molar ratio of aluminum to titanium is 1:(2-7);

[0026] The phosphate is selected from one or more of (NH4)2HPO4, NH4H2PO4, Na3PO4, K3PO4, Na2HPO4, K2HPO4, NaH2PO4, and KH2PO4;

[0027] The amount of phosphate used is such that the molar ratio of phosphate to aluminum in the aluminum salt is (8-12):1.

[0028] Preferably, the high-nickel cathode precursor has the following composition:

[0029] Ni x M (1-x) (OH)2 Formula II;

[0030] In Equation II, 0.6 ≤ x < 1;

[0031] M is selected from one or more of Co, Mn, B, Mg, Al, Zr, Sr, and Mo;

[0032] The specific surface area of ​​the high-nickel cathode precursor is 3–25 m². 2 / g, the D50 of the high-nickel cathode precursor is 2-18μm.

[0033] Preferably, the temperature during the co-precipitation process is 25–75°C, the time is 20–60 min, and the pH value is 10.00–12.00.

[0034] Preferably, the lithium source is selected from lithium hydroxide and / or lithium carbonate;

[0035] The molar ratio of lithium in the coated product and the lithium source is 1:(1 to 1.08).

[0036] Preferably, oxygen is introduced during the sintering process;

[0037] The sintering method includes:

[0038] Heat to the first temperature and hold for a first time, then heat to the second temperature and hold for a second time.

[0039] The first temperature is 550–650℃, and the first time is 3–5 hours;

[0040] The second temperature is 700–1200℃, and the second time is 8–12 hours.

[0041] The present invention provides a battery comprising: the high-voltage, high-nickel cathode material described in the above technical solution, or the high-voltage, high-nickel cathode material prepared by the method described in the above technical solution.

[0042] This invention involves sintering a modified high-nickel cathode precursor with a lithium source to obtain a compound coating layer with a spinel phase structure (such as CoAl2O4 or Co2TiO4) and a fast ion conductor phase (such as Li3PO4). The spinel phase is more stable than the layered structure of the bulk phase under high voltage, which can improve the thermal stability and high voltage overshoot resistance of the cathode material, i.e., its high voltage characteristics. The fast ion conductor can increase the rate of lithium ion extraction and insertion, reduce the internal resistance of the battery system, and increase the energy density of the material.

[0043] This invention employs a precipitation method to uniformly coat a layer of metal hydroxide onto the surface of a high-nickel cathode precursor. After lithium mixing and sintering, a high-nickel cathode material with a spinel and fast-ion conductor coating is obtained. The coating prepared by this invention not only stabilizes its layered structure and suppresses phase transitions during charge and discharge, but also improves its resistance to high-voltage overcharge and cycle performance.

[0044] This invention prepares a coated high-nickel cathode material that can suppress problems such as gas generation deterioration and cycle degradation caused by voltage rise, thereby improving the stability of the cathode particle structure. This invention employs a co-precipitation method to prepare a modified high-nickel precursor with uniformity and good consistency; after mixing the modified precursor with lithium and sintering, a high-nickel cathode material with a spinel and fast-ion conductor coating layer is obtained. The cathode material prepared by this invention has advantages such as high energy density and good cycle performance. The raw materials used in the preparation process of the cathode material in this invention are simple to prepare and have good processing performance, making it suitable for industrial-scale mass production and possessing broad application prospects. Attached Figure Description

[0045] Figure 1 A process flow diagram of the high-voltage cathode material preparation method provided in the embodiments of the present invention;

[0046] Figure 2 This is a SEM image of the high-voltage, high-nickel cathode material prepared in Example 1 of the present invention;

[0047] Figure 3 A comparison of the growth rate of DC resistance (DCR) of the high-voltage, high-nickel cathode material prepared in Example 1 of this invention before and after coating in a soft-pack full cell under high-temperature cycling conditions of 3.0V to 4.6V, 1C charge-discharge, and 45°C.

[0048] Figure 4 The high-voltage, high-nickel cathode material prepared in Example 1 of this invention exhibits changes in a soft-pack full cell before and after coating under 3.0V–4.6V, 1C charge-discharge, and 45°C high-temperature cycling conditions.

[0049] Figure 5 The change in coin cell specific capacity of the high-voltage, high-nickel cathode material prepared in Example 1 of this invention before and after coating under charge-discharge conditions of 3.0–4.55V and 1C is shown.

[0050] Figure 6 This is a comparison chart showing the volume change of a soft-pack full cell at 80°C with the number of days before and after coating of the high-voltage, high-nickel cathode material prepared in Example 1 of the present invention. Detailed Implementation

[0051] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] This invention provides a high-voltage, high-nickel cathode material, comprising:

[0053] Matrix;

[0054] A coating layer disposed on the surface of the substrate;

[0055] The coating layer comprises a spinel-structured compound and a fast-ion conductor phase compound.

[0056] In this invention, the specific surface area of ​​the high-voltage, high-nickel cathode material is preferably 0.2–1.5 m². 2 / g, more preferably 0.5 to 1.0m 2 / g, the optimal value is 0.6–0.8m 2 / g; the D50 of the high-voltage high-nickel cathode material is preferably 2.0-18.0μm, more preferably 5.0-15.0μm, even more preferably 8.0-12.0μm, and most preferably 10.0μm.

[0057] In this invention, the preferred composition of the matrix is:

[0058] LiNi x M (1-x) O2 Formula I;

[0059] In Equation I, 0.6 ≤ x < 1,

[0060] M is selected from at least two of the following: Co, Mn, B, Mg, Al, Zr, Sr, Mo, Ti, and P.

[0061] In this invention, in Formula I, x is preferably 0.7 to 0.9, and more preferably 0.8.

[0062] In this invention, the spinel structure compound preferably includes CoAl2O4 and Co2TiO4.

[0063] In this invention, the fast ion conductor phase compound is preferably Li3PO4.

[0064] This invention provides a method for preparing the high-voltage, high-nickel cathode material described in the above technical solution, comprising:

[0065] Solution A, solution B and solution M were mixed and coprecipitated to obtain the coated product;

[0066] The coated product and lithium source are mixed and then sintered to obtain a high-voltage, high-nickel cathode material.

[0067] Solution A is a mixed solution of aluminum salt and titanium salt;

[0068] Solution B is a phosphate solution;

[0069] The solution M is a solution containing a high-nickel cathode precursor.

[0070] In this invention, the method for preparing solution A preferably includes:

[0071] Aluminum salt, titanium salt and water are mixed to obtain solution A.

[0072] In this invention, the aluminum salt is preferably a soluble aluminum salt, more preferably a soluble aluminum metal salt, and most preferably selected from aluminum nitrate and / or sodium aluminate. In this invention, the titanium salt is preferably a soluble titanium salt, more preferably selected from ammonium fluorotitanate and / or titanium oxysulfate. In this invention, the ratio of aluminum salt to titanium salt is preferably such that the molar ratio of aluminum to titanium is 1:(2-7), more preferably 1:(3-6), and most preferably 1:(4-5). In this invention, the water is preferably deionized water.

[0073] In this invention, the method for preparing solution B preferably includes:

[0074] Phosphate and water are mixed to obtain solution B.

[0075] In this invention, the phosphate is preferably a soluble phosphate, more preferably selected from one or more of (NH4)2HPO4, NH4H2PO4, Na3PO4, K3PO4, Na2HPO4, K2HPO4, NaH2PO4, and KH2PO4. In this invention, the amount of phosphate used is such that the molar ratio of phosphate to aluminum in the aluminum salt is preferably (8-12):1, more preferably (9-11):1, and most preferably 10:1. In this invention, the water is preferably deionized water.

[0076] In this invention, the method for preparing solution M preferably includes:

[0077] High-nickel cathode precursor powder was mixed with water to obtain solution M (suspension).

[0078] In this invention, the preferred composition of the high-nickel cathode precursor is:

[0079] Ni x M (1-x) (OH)2 Formula II;

[0080] In Equation II, 0.6 ≤ x < 1;

[0081] M is selected from one or more of Co, Mn, B, Mg, Al, Zr, Sr, and Mo.

[0082] In this invention, in Formula II, x is preferably 0.7 to 0.9, and more preferably 0.8.

[0083] In this invention, the specific surface area of ​​the high-nickel cathode precursor powder is preferably 3 to 25 m². 2 / g, more preferably 5-20m 2 / g, the most preferred value is 10-15m 2 / g; the D50 of the high-nickel cathode precursor powder is preferably 2-18μm, more preferably 5-15μm, more preferably 8-12μm, and most preferably 10μm.

[0084] In this invention, the water is preferably deionized water.

[0085] In this invention, the mass ratio of the high-nickel cathode precursor powder to water is preferably (0.5-5):1, more preferably (1-4):1, and most preferably (2-3):1.

[0086] In this invention, the mass ratio of solution A, solution B and solution M is preferably (0.01-1):(0.01-2):(1-20), more preferably (0.05-0.8):(0.05-1.5):(5-15), even more preferably (0.1-0.6):(0.1-1.0):(8-12), and most preferably (0.3-0.5):(0.3-0.6):10.

[0087] In this invention, the co-precipitation is preferably carried out in a constant temperature water bath, and the temperature during the co-precipitation process is preferably 25-75°C, more preferably 30-70°C, even more preferably 40-60°C, and most preferably 50°C; the co-precipitation time is preferably 20-60 min, more preferably 30-50 min, and most preferably 40 min; the pH value during the co-precipitation process is preferably adjusted by an alkaline solution, and the pH value during the co-precipitation process is preferably 10.00-12.00, more preferably 10.5-11.5, and most preferably 11; the alkaline solution is preferably sodium hydroxide solution and / or ammonia water.

[0088] In this invention, during the co-precipitation process, solution A and solution B are preferably slowly added to suspension M, stirred rapidly, and kept in a constant temperature water bath. At the same time, the pH value of the solution is adjusted by alkaline solution so that the complexes and hydroxides formed by Al, Ti and phosphate are uniformly deposited on the surface of high nickel cathode precursor particles, nucleating and slowly growing on the particle surface to achieve uniform coating on the material surface.

[0089] In this invention, the co-precipitation process preferably further includes:

[0090] The obtained product was filtered and dried to obtain a surface-modified substrate (coated product);

[0091] The surface-modified substrate and lithium source are mixed and then sintered.

[0092] In this invention, the filtration is preferably carried out using a Buchner funnel; the drying is preferably carried out using an oven; and the drying temperature is preferably 130-170°C, more preferably 140-160°C, and most preferably 150°C.

[0093] In this invention, the lithium source is preferably selected from lithium hydroxide and / or lithium carbonate.

[0094] In this invention, the molar ratio of the coated product (surface-modified substrate) to lithium in the lithium source is preferably 1:(1 to 1.08), more preferably 1:(1.02 to 1.06), and most preferably 1:1.04.

[0095] In this invention, the mixing is preferably high-speed mixing.

[0096] In this invention, the sintering is preferably carried out in a muffle furnace; oxygen is preferably introduced during the sintering process. In this invention, the sintering method preferably includes:

[0097] Heat to the first temperature and hold for a first time, then heat to the second temperature and hold for a second time.

[0098] In this invention, the first temperature is preferably 550-650℃, more preferably 580-620℃, and most preferably 600℃; the first time is preferably 3-5h, more preferably 4h; the second temperature is preferably 700-1200℃, more preferably 800-1100℃, and most preferably 900-1000℃; the second time is preferably 8-12h, more preferably 9-11h, and most preferably 10h.

[0099] In this invention, the process after sintering preferably further includes:

[0100] The sintered product is cooled, crushed, and sieved in the furnace to obtain a high-voltage, high-nickel cathode material.

[0101] In an embodiment of the present invention, the process flow diagram of the preparation method of the high-voltage high-nickel cathode material is as follows: Figure 1 As shown, it includes:

[0102] High-nickel cathode precursor powder was added to a deionized aqueous solution to obtain suspension M;

[0103] A measured amount of soluble aluminum salt and titanium salt were dissolved in a deionized aqueous solution to obtain solution A;

[0104] Weigh out the soluble phosphate and dissolve it in deionized water to obtain solution B;

[0105] Solution A and solution B are slowly added to suspension M, stirred rapidly, and kept in a constant temperature water bath. At the same time, the pH value of the solution is adjusted by alkaline solution, so that the complexes and hydroxides formed by Al, Ti and phosphate are uniformly deposited on the surface of high nickel cathode precursor particles, nucleating and slowly growing on the particle surface to achieve uniform coating on the material surface; filtered in Buchner funnel and dried in oven to obtain surface-modified substrate.

[0106] The surface-modified substrate and lithium source are mixed at high speed and then sintered in an oxygen-filled muffle furnace. After cooling in the furnace, the material is crushed and sieved to obtain a high-voltage, high-nickel cathode material.

[0107] The present invention provides a battery comprising: the high-voltage, high-nickel cathode material described in the above technical solution, or the high-voltage, high-nickel cathode material prepared by the method described in the above technical solution.

[0108] In this invention, the positive electrode material in the battery is preferably the high-voltage, high-nickel positive electrode material described in the above technical solution.

[0109] In this invention, the battery is preferably selected from button cells or pouch cells, such as button CR2032 batteries.

[0110] The present invention does not impose any special restrictions on the preparation method of the battery. It can be prepared by using the above-mentioned high-voltage high-nickel cathode material as the cathode material according to the battery preparation method known to those skilled in the art.

[0111] In this invention, the preferred method for preparing the coin cell CR2032 battery includes:

[0112] High-voltage, high-nickel cathode material, acetylene black, and polyvinylidene fluoride are mixed and added to NMP to obtain a slurry;

[0113] The slurry is coated onto aluminum foil, baked, pressed, and cut to obtain a positive electrode sheet;

[0114] The positive electrode, negative electrode, electrolyte, and separator are assembled to obtain the CR2032 battery.

[0115] In this invention, the preferred mass ratio of the high-voltage high-nickel cathode material, acetylene black, and polyvinylidene fluoride is (97-98):(2-3):(2-3), and more preferably 97:2.5:2.5.

[0116] In this invention, it is preferable to stir after adding NMP, and the stirring time is preferably 1 to 3 hours, more preferably 1.5 to 2.5 hours, and most preferably 2 hours.

[0117] In this invention, the slurry is preferably a viscous slurry; it is preferably uniformly coated on aluminum foil.

[0118] In this invention, the baking is preferably vacuum baking, and the baking temperature is preferably 70-90°C, more preferably 75-85°C, and most preferably 80°C.

[0119] In this invention, the cutting is preferably to obtain a positive electrode sheet with a diameter of 13 to 15 mm, more preferably 14 mm.

[0120] In this invention, the negative electrode sheet is preferably a pure lithium sheet; the diameter of the negative electrode sheet is preferably 14-18 mm, more preferably 15-17 mm, and most preferably 16 mm.

[0121] In this invention, the electrolyte is preferably a 1 mol / L LiPF6+DEC / EC (volume ratio 1:1) mixed solution.

[0122] In this invention, the diaphragm is preferably a polyCelgard propylene microporous membrane.

[0123] In this invention, the assembly is preferably carried out in a glove box filled with argon gas.

[0124] In this invention, the preferred method for preparing the pouch cell includes:

[0125] The conductive agent, binder, and NMP are mixed and then added to a high-voltage, high-nickel cathode material to obtain a slurry;

[0126] The slurry is coated onto the current collector aluminum foil, then dried, cut, and rolled to obtain small electrode sheets;

[0127] After welding the small electrode sheet to the tab, it is wound together with the negative electrode sheet and the separator to assemble a battery cell.

[0128] The battery cell is placed in a soft-pack aluminum-plastic film, sealed and welded, dried, and then injected with electrolyte.

[0129] After the electrolyte is injected, the battery is soaked, then vacuum pre-sealed, then soaked again and divided into volumes. After removing excess gas and electrolyte, the battery is sealed to obtain a soft-pack battery.

[0130] In this invention, the conductive agent is preferably acetylene black; the binder is preferably polyvinylidene fluoride.

[0131] In this invention, the mixing is preferably carried out in a vacuum mixer.

[0132] In this invention, the high-voltage, high-nickel cathode material is preferably pre-dried.

[0133] In this invention, the preferred mass ratio of the high-voltage high-nickel cathode material, binder, and conductive agent is (94-95):(2-3):(2-4), and more preferably 94.5:2.5:3.

[0134] In this invention, the addition of high-voltage, high-nickel cathode material is preferably obtained by completely stirring to obtain a slurry.

[0135] In this invention, it is preferable to sieve the slurry and then coat it onto the current collector aluminum foil.

[0136] In this invention, the drying is preferably vacuum drying; after rolling, the electrode sheet is preferably cut into small electrode sheets of 374×41mm.

[0137] In this invention, the electrode tab is preferably an aluminum strip electrode tab.

[0138] In this invention, the negative electrode sheet is preferably a graphite negative electrode sheet.

[0139] In this invention, the size of the diaphragm is preferably 401×42mm.

[0140] In this invention, the flexible aluminum-plastic film is preferably the 053048 model flexible aluminum-plastic film.

[0141] In this invention, the sealing welding is preferably performed by using a top-side sealing machine to seal the side and top tab portions of the soft battery.

[0142] In this invention, the drying is preferably vacuum drying, the drying temperature is preferably 70-90°C, more preferably 75-85°C, and most preferably 80°C; the drying time is preferably not less than 4 hours.

[0143] In this invention, the electrolyte used for injection is preferably LiF6PO4; the concentration of the electrolyte is preferably 0.5-1.5 mol / L, more preferably 0.8-1.2 mol / L, and most preferably 1.0 mol / L.

[0144] In this invention, the soaking time is preferably 0.5 to 1.5 hours, more preferably 1 hour; the re-soaking is preferably carried out at room temperature for 20 to 30 hours, more preferably 24 hours.

[0145] In this invention, the capacity allocation is preferably done on the upper cabinet.

[0146] In this invention, the extraction of excess gas and electrolyte is preferably achieved by puncturing the soft-pack airbag using a vacuum sealing machine.

[0147] In this invention, the sealing is preferably a vacuum seal.

[0148] This invention employs a precipitation method to uniformly coat a layer of metal hydroxide onto the surface of a high-nickel cathode precursor. After lithium mixing and sintering, a high-nickel cathode material with a spinel and fast-ion conductor coating is obtained. The coating prepared by this invention not only stabilizes its layered structure and suppresses phase transitions during charge and discharge, but also improves its resistance to high-voltage overcharge and cycle performance.

[0149] The high-nickel ternary precursors in the following embodiments of the present invention were provided by Ningbo Ronbay New Energy Technology Co., Ltd.

[0150] Example 1

[0151] In a 2L beaker, add 1kg of deionized water and weigh out 1kg of high-nickel ternary precursor Ni. 0.84 Co 0.08 Mn 0.08 Add (OH)2 powder to a beaker;

[0152] Weigh 21.3g of aluminum nitrate and 39.4g of ammonium fluorotitanate and dissolve them in 50ml of deionized water to obtain solution A;

[0153] Weigh 105.6g of (NH4)2HPO4 and dissolve it in deionized water to obtain solution B;

[0154] Solution A and solution B were slowly added to the 2L beaker, stirred rapidly, and kept in a constant temperature water bath at 50°C. The pH of the solution was adjusted to 10.60 using sodium hydroxide solution. The reaction time was 60 minutes. The mixture was then filtered through a Buchner funnel and dried in an oven at 150°C to obtain the surface-modified substrate.

[0155] The surface-modified substrate and Li in LiOH were mixed at a molar ratio of 1:1.02 and then placed in an oxygen-filled muffle furnace. The mixture was heated from room temperature to 600°C and held for 4 hours, then heated to 830°C and held for 10 hours for sintering. After furnace cooling, the mixture was crushed and sieved to obtain the high-voltage, high-nickel cathode material LiNi. 0.84 Co 0.08 Mn 0.08 O2.

[0156] Example 2

[0157] In a 2L beaker, add 1kg of deionized water and weigh out 1kg of high-nickel ternary precursor Ni.0.90 Co 0.08 Mn 0.02 Add (OH)2 powder to a beaker;

[0158] Weigh 8.20g of sodium aluminate and 98.5g of ammonium fluorotitanate and dissolve them in 50ml of deionized water to obtain solution A;

[0159] Weigh 115g of NH4H2PO4 and dissolve it in deionized water to obtain solution B;

[0160] Solution A and solution B were slowly added to the 2L beaker, stirred rapidly, and kept in a constant temperature water bath at 50°C. The pH of the solution was adjusted to 11.00 using sodium hydroxide solution. The reaction time was 360 min. The mixture was then filtered through a Buchner funnel and dried in an oven at 150°C to obtain the surface-modified substrate.

[0161] The surface-modified substrate and Li in LiOH were mixed at a molar ratio of 1:1.04 and then placed in an oxygen-filled muffle furnace. The mixture was heated from room temperature to 600°C and held for 4 hours, then heated to 790°C and held for 10 hours for sintering. After furnace cooling, the mixture was crushed and sieved to obtain the high-voltage, high-nickel cathode material LiNi. 0.90 Co 0.08 Mn 0.02 O2.

[0162] Example 3

[0163] In a 2L beaker, add 1kg of deionized water and weigh out 1kg of high-nickel ternary precursor Ni. 0.96 Co 0.03 Mn 0.01 Add (OH)2 powder to a beaker;

[0164] Weigh 8.20g of sodium aluminate and 85g of ammonium fluorotitanate and dissolve them in 50ml of deionized water to obtain solution A;

[0165] Weigh 145.2g of K3PO4 and dissolve it in deionized water to obtain solution B;

[0166] Solution A and solution B were slowly added to the 2L beaker, stirred rapidly, and kept in a constant temperature water bath at 40°C. The pH of the solution was adjusted to 11.90 with sodium hydroxide. The reaction time was 600 min. After filtration in a Buchner funnel, the solution was dried in an oven at 150°C to obtain the surface-modified substrate.

[0167] The surface-modified substrate and Li in LiOH were mixed at a molar ratio of 1:1.02 and then placed in an oxygen-filled muffle furnace. The mixture was heated from room temperature to 600°C and held for 4 hours, then heated to 740°C and held for 10 hours for sintering. After furnace cooling, the mixture was crushed and sieved to obtain the high-voltage, high-nickel cathode material LiNi. 0.96 Co 0.03 Mn 0.01 O2.

[0168] Example 4

[0169] In a 2L beaker, add 1kg of deionized water and weigh out 1kg of high-nickel ternary precursor Ni. 0.65 Co 0.10 Mn 0.25 Add (OH)2 powder to a beaker;

[0170] Weigh 17.2g of sodium aluminate and 128g of titanium oxysulfate and dissolve them in 50ml of deionized water to obtain solution A;

[0171] Weigh 196.8g of Na3PO4 and dissolve it in deionized water to obtain solution B;

[0172] Solution A and solution B were slowly added to a 2L beaker, stirred rapidly, and kept in a constant temperature water bath at 70℃. The pH of the solution was adjusted to 11.90 with sodium hydroxide. The reaction time was 480 min. After filtration in a Buchner funnel, the solution was dried in an oven at 150℃ to obtain the surface-modified substrate.

[0173] The surface-modified substrate and Li in LiOH were mixed at a molar ratio of 1:1.08 and then placed in an oxygen-filled muffle furnace. The mixture was heated from room temperature to 600°C and held for 4 hours, then heated to 1050°C and held for 10 hours for sintering. After furnace cooling, the mixture was crushed and sieved to obtain the high-voltage, high-nickel cathode material LiNi. 0.65 Co 0.10 Mn 0.25 O2.

[0174] Performance testing

[0175] The preparation method of uncoated cathode material is as follows:

[0176] Using the high-nickel ternary precursor and lithium source from Examples 1-4, and the corresponding amounts of substances, the high-nickel ternary precursor and lithium source are mixed in a high-speed mixing device and calcined in an oxygen-filled muffle furnace (the calcination method and process parameters are the same as those in Examples 1-4). After exiting the furnace, the mixture is crushed by a jaw crusher, pulverized by roller crushing, and sieved to obtain uncoated high-nickel cathode material.

[0177] Fabrication of coin cell CR2032 batteries:

[0178] The high-nickel cathode material with composite coating prepared in Examples 1-4 and the uncoated cathode material were assembled into a coin cell. The specific method is as follows: the high-nickel cathode material with composite coating, acetylene black and polyvinylidene fluoride (PVDF) were weighed at a mass ratio of 95:2.5:2.5, mixed evenly, NMP was added and stirred for 2 hours to form a viscous slurry, which was evenly coated on aluminum foil, then vacuum baked at 80°C, pressed into sheets, and cut into cathode sheets with a diameter of 14 mm; a pure lithium sheet with a diameter of 16 mm was used as the anode sheet, a 1 mol / L LiPF6 + DEC / EC (volume ratio 1:1) mixed solution was used as the electrolyte, and a polyCelgard propylene microporous membrane was used as the separator. The cells were assembled into coin cells CR2032 batteries in an argon-filled glove box.

[0179] Fabrication of pouch cells:

[0180] The conductive agent acetylene black (SP) and the binder polyvinylidene fluoride (PVDF) were added to a certain amount of NMP in a certain proportion and stirred thoroughly in a vacuum mixer. Then, the pre-dried high-nickel cathode material with a composite coating prepared in Examples 1-4 and the uncoated cathode material were added (mass ratio of cathode: binder: conductive agent = 94.5:2.5:3) and stirred thoroughly until homogeneous (a uniform and stable paste) to obtain a slurry. After sieving, the slurry was uniformly coated onto the current collector aluminum foil. After vacuum drying, the electrode sheets were cut into small electrode sheets of 374×41mm by rolling. After welding the aluminum strip tabs, the graphite negative electrode sheet and separator (401×42mm) are wound and assembled into a cell. The cell is then placed in a 053048 model soft-pack aluminum-plastic film. The side and top tabs of the soft battery are sealed and welded using a top-side sealing machine. After vacuum drying at 80℃ for no less than 4 hours, the battery is injected with electrolyte (1mol / L LiF6PO4). After the electrolyte is injected, the battery is soaked for 1 hour and then vacuum pre-sealed. After pre-sealing, the battery is soaked at room temperature for 24 hours before being tested for capacity. After capacity testing, the soft-pack safety airbag is punctured by a secondary vacuum sealing machine to extract excess gas and electrolyte before vacuum sealing.

[0181] Figure 2 The high-voltage, high-nickel cathode material LiNi prepared in Example 1 of this invention 0.84 Co 0.08 Mn 0.08 The SEM image of O2 shows that the average particle size is between 2.5 μm and 3 μm.

[0182] DC resistance testing was performed on the pouch cells obtained using the cathode material prepared in Example 1 (S1: 1C full charge, constant voltage cutoff current 20mA, rest for 5min; S2: 1C discharge to 50% DOD according to battery capacity, rest for 1h; S3: 5C discharge for 10s; S4: test ends). The test results are as follows: Figure 3As shown, it can be seen that after making a pouch cell with the positive electrode materials before and after coating, the DC resistance growth rate of the coated sample increases more slowly with the number of cycles, reaching 21.0% after 300 cycles; the DC resistance of the uncoated sample increases more rapidly, reaching 186.0% after 300 cycles.

[0183] The capacity retention rate of the pouch cells obtained using the cathode material prepared in Example 1 was tested (S1: placed in a 45℃ incubator, S2: 4.2~3V, constant voltage cutoff current 20mA, rested for 5min during charge and discharge, 1C / 1C rate). The test results are as follows. Figure 4 As shown, the capacity retention rate of the coated battery after 300 cycles is still 92.8%, while the uncoated sample shows a sharp drop in capacity in the later stages of cycling.

[0184] The capacity retention performance of the coin-type CR2032 battery obtained using the cathode material prepared in Example 1 was tested (initial cycle: 0.2C / 0.2C charge / discharge, followed by 0.5C charge, and then 0.1C, 0.2C, 0.5C, 1C, 1.3C, and 1.5C discharge cycles respectively; initial cycle: 0.2C / 0.2C charge / discharge, followed by 0.5C / 1C charge / discharge cycles for 150 cycles). The test results are as follows: Figure 5 As shown, it can be seen that, before and after coating the cathode material, under 1C / 1C charge-discharge cycles, the capacity of the coin cell half-cell after 100 cycles is significantly increased from 49.6% without coating to 75.4% after coating.

[0185] Volume growth was measured in the pouch cells obtained using the cathode material prepared in Example 1 (fully charged cells were stored according to process requirements (e.g., 70°C / 7 days), and the volume change before and after storage was measured. At the end of the storage period, a heat test was performed at 70°C for approximately 120 minutes, followed by a cold test at room temperature using the water displacement method). The results are as follows: Figure 6 As shown, the volume growth rate of the cathode material after 21 days of storage at 80℃ decreased from 103.9% in the uncoated sample to 23.5%.

[0186] The high-voltage, high-nickel cathode materials prepared in Examples 2 to 4 of this invention were tested according to the above method. The test results are as follows: In Example 2, the DCR growth rate of the high-voltage, high-nickel cathode material used in a pouch cell decreased from 201.2% to 37.6% after 300 cycles; the capacity retention rate of the coated battery after 300 cycles remained at 89.4%; the capacity retention rate of the coin cell increased from 32% to 70.3%; and the high-temperature storage volume change rate decreased from 109.7% to 26.1%. In Example 3, the DCR growth rate of the high-voltage, high-nickel cathode material used in a pouch cell decreased from 191.5% to 39.7% after 300 cycles; the capacity retention rate of the coated battery after 300 cycles remained at 86.7%; the capacity retention rate of the coin cell increased from 24.5% to 63.8%; and the high-temperature storage volume change rate decreased from 112.5% ​​to 30.3%. The high-voltage, high-nickel cathode material prepared in Example 4, when used to make a pouch cell, showed that the DCR growth rate decreased from 173.0% to 15.8% after 300 cycles; the capacity retention rate of the coated cell remained at 96.3% after 300 cycles; the capacity retention rate of the coin cell increased from 53.5% to 84.9%; and the volume change rate during high-temperature storage decreased from 89.1% to 18.3%.

[0187] This invention uses a co-precipitation method to prepare a uniform and consistent modified high-nickel precursor; after sintering the modified precursor with lithium, a high-nickel cathode material with spinel and fast ion conductor coating is obtained; the prepared high-nickel cathode material has high voltage characteristics.

[0188] While the invention has been described and illustrated with reference to specific embodiments thereof, such description and illustration are not intended to limit the invention. It will be readily understood by those skilled in the art that various changes may be made to suit particular circumstances, materials, compositions, substances, methods, or processes to the objectives, spirit, and scope of this application without departing from the true spirit and scope of the invention as defined by the appended claims. All such modifications are intended to be within the scope of the appended claims. Although the methods disclosed herein have been described with reference to specific operations performed in a particular order, it should be understood that these operations may be combined, subdivided, or reordered to form equivalent methods without departing from the teachings of the invention. Therefore, unless specifically indicated herein, the order and grouping of operations are not a limitation of this application.

Claims

1. A high-voltage high-nickel positive electrode material, comprising: a substrate; a coating layer disposed on a surface of the substrate; the coating layer comprises a spinel structure compound and a fast ion conductor phase compound; the spinel structure compound comprises CoAl2O4 and Co2TiO4; and the fast ion conductor phase compound is Li3PO4; The high-voltage high-nickel positive electrode material has a specific surface area of 0.2-1.5 m 2 / g, and a D50 of 2.0-18.0 μm; and the base component has a formula: LiNi x M (1-x) O2 Formula I; in formula I, 0.6≤x<1, M is selected from at least two of Co, Mn, B, Mg, Al, Zr, Sr, Mo, Ti, and P. 2.A method for preparing the high-voltage high-nickel positive electrode material of claim 1, comprising: mixing solution A, solution B, and solution M to perform co-precipitation to obtain a coated product; mixing the coated product and a lithium source, and then performing sintering to obtain the high-voltage high-nickel positive electrode material; the solution A is a mixed solution of an aluminum salt and a titanium salt; the aluminum salt is selected from aluminum nitrate and / or sodium metaaluminate; and the titanium salt is selected from ammonium fluorotitanate and / or titanyl sulfate; the solution B is a phosphate salt solution; the solution M is a solution containing a high-nickel positive electrode precursor; the high-nickel positive electrode precursor has a composition formula as follows: Ni x M (1-x) (OH)2 Formula II; in formula II, 0.6≤x<1; M is selected from one or more of Co, Mn, B, Mg, Al, Zr, Sr, and Mo. 3.The method of claim 2, wherein: the aluminum salt and the titanium salt are used in a ratio such that the molar ratio of aluminum to titanium is 1: (2-7) ; the phosphate salt is selected from one or more of (NH4) 2HPO4, NH4H2PO4, Na3PO4, K3PO4, Na2HPO4, K2HPO4, NaH2PO4, and KH2PO4; the phosphate salt is used in a ratio such that the molar ratio of phosphate to aluminum in the aluminum salt is (8-12) :

1. 4.The method of claim 2, wherein: The specific surface area of the high-nickel positive electrode precursor is 3-25 m 2 / g, and the D50 of the high-nickel positive electrode precursor is 2-18 μm.

5. The method of claim 2, wherein, the temperature during the co-precipitation process is 25-75℃, the time is 20-60 min, and the pH value is 10.00-12.

00.

6. The method of claim 2, wherein, the lithium source is selected from lithium hydroxide and / or lithium carbonate; the molar ratio of lithium in the coated product to the lithium source is 1: (1-1.08).

7. The method of claim 2, wherein, oxygen is introduced during the sintering process; the sintering method comprises: increasing the temperature to a first temperature, maintaining the temperature for a first time, then increasing the temperature to a second temperature, and maintaining the temperature for a second time; the first temperature is 550-650℃, and the first time is 3-5 h; the second temperature is 700-1200℃, and the second time is 8-12 h.

8. A battery comprising: the high-voltage high-nickel positive electrode material of claim 1, or the high-voltage high-nickel positive electrode material prepared by the method of any one of claims 2-7.

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