High-voltage nickel-manganese positive electrode material and preparation method thereof

Abstract

The application provides a high-voltage nickel-manganese positive electrode material and a preparation method thereof, and the chemical formula is LiNi 0.5‑a Mn 1.5‑b X c P d O4 formula I, wherein X is one or more of W, Ta, Ru, Mo, Te, Mg, Nb, V, Sr, Zr, Co, Ti, Cu, Cr, Si, Sc, Y, Cu, Zn, Fe, Al, B; in the high-voltage nickel-manganese positive electrode material, the doping rate of P is 30-95%, and the volume V p of the P-doped region satisfies the relationship shown in formula II: the high-voltage nickel-manganese positive electrode material in the application has high specific capacity, excellent rate performance and cycle performance, and the wet coating method is adopted in the application, compared with the dry doping method, the P doping rate can be increased to 30-95%, and the doping effect is significantly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion batteries, and particularly relates to a high-voltage nickel-manganese positive electrode material and a preparation method thereof. BACKGROUND

[0002] With the increasing depletion of fossil energy (such as oil) and the pursuit of environmental protection, new energy vehicles gradually replace traditional fuel vehicles. Lithium ion batteries are an important part of new energy vehicles, and the cost accounts for as high as 40%. Lithium ion batteries have the advantages of high capacity and long cycle life. The commercialized lithium battery positive electrode materials at present include layered LiCoO2, layered LiNi x Co y Mn z O2 (x+y+z=1), olivine LiFePO4, spinel LiMnO4, etc. LiCoO2 has high volume energy density, but is expensive and is mainly used in the field of 3C; LiNi x Co y Mn z O2 has high specific capacity and is a mainstream material for power batteries, but has poor safety; LiFePO4 is low in price and high in safety, but has low energy density and is difficult to effectively solve the problem of "range anxiety"; LiMnO4 has simple production process and high energy density, but has serious Mn dissolution problem and poor high-temperature performance.

[0003] Spinel LiNi 0.5 Mn 1.5 O4 gradually develops on the basis of LiMnO4, and the specific capacities of the two are similar (~146.7 mAh / g), but the working voltage (4.75 V) of LiNi 0.5 Mn 1.5 O4 is about 19% higher than that (4 V) of LiMnO4, and has higher energy density and great application potential. However, LiNi 0.5 Mn 1.5 O4 also has problems of Mn dissolution in the cycle process and poor high-temperature performance, and doping is a common modification method. The traditional doping method is usually a solid-phase mixing method, which is simple in process and easy to industrialize, but the doping elements are difficult to uniformly mix with the precursor, and the prepared positive electrode material has poor performance. Wet doping can mix with the precursor at the atomic level, significantly improving the doping effect. As a non-metallic dopant, P can effectively improve the electrochemical performance of spinel LiNi 0.5 Mn 1.5 O4, but the current P doping process is mainly dry doping, and there are few reports on wet doping, and the main reason is that P is difficult to dope in the precursor through the coprecipitation method. Surface doping is to maintain spinel LiNi 0.5 Mn 1.5 O4.O4 structure is stable, and the high surface doping element concentration can better protect the material from being corroded by the electrolyte. Therefore, it is necessary to develop an economical and practical wet P surface doping scheme to optimize the performance of high-voltage lithium nickel manganese oxide materials. SUMMARY

[0004] The application aims to provide a high-voltage nickel-manganese positive electrode material and a preparation method thereof.

[0005] The application provides a high-voltage nickel-manganese positive electrode material, which has a chemical formula of LiNi 0.5-a Mn 1.5-b X c P d O4 formula I, wherein 0≤a≤0.2, 0≤b≤0.2, 0

[0006] X is one or more of W, Ta, Ru, Mo, Te, Mg, Nb, V, Sr, Zr, Co, Ti, Cu, Cr, Si, Sc, Y, Cu, Zn, Fe, Al, B;

[0007] The doping rate of P in the high-voltage nickel-manganese positive electrode material is 30-95%, and the volume V p of the P-doped region satisfies the relationship shown in formula II:

[0008]

[0009] Preferably, the tap density of the high-voltage nickel-manganese positive electrode material is 1.2-2.4 g / cm 3 , D50 is 4-12 μm, and BET is 0.2-0.7 m 2 / g.

[0010] Preferably, the high-voltage nickel-manganese positive electrode material has at least one of a regular octahedron morphology, a truncated octahedron morphology, a spherical morphology, and a quasi-spherical morphology.

[0011] When the high-voltage nickel-manganese positive electrode material has a regular octahedron morphology, V p satisfies the relationship shown in formula III:

[0012] When the high-voltage nickel-manganese positive electrode material has a truncated octahedron morphology, V p satisfies the relationship shown in formula IV:

[0013] When the high-voltage nickel-manganese positive electrode material has a spherical morphology, V p satisfies the relationship shown in formula V:

[0014] When the high-voltage nickel-manganese positive electrode material has a spherical morphology or a spherical-like morphology, V p satisfies the relationship shown in formula VI:

[0015] The application provides a preparation method of the high-voltage nickel-manganese positive electrode material as described above, comprising the following steps:

[0016] A) adding a P source and a Ni 0.5 Mn 1.5 (OH)4 precursor into deionized water to obtain a suspension A;

[0017] B) optionally adding an aqueous LiOH solution to obtain a suspension B;

[0018] C) drying the suspension A or B to obtain a P element-coated Ni 0.5 Mn 1.5 (OH)4 precursor;

[0019] D) mixing a lithium source, an additive containing X and the P element-coated Ni 0.5 Mn 1.5 (OH)4 precursor, and sintering to obtain the high-voltage nickel-manganese positive electrode material LiNi 0.5-a Mn 1.5-b X c P d O4.

[0020] Preferably, the P source is one or more of NH4H2PO4, (NH4)2HPO4, (NH4)3PO4 and H3PO4.

[0021] The mass concentration of the P source in the solution A is 5-20 g / L.

[0022] Preferably, the molar ratio of the P source to the Ni 0.5 Mn 1.5 (OH)4 precursor is 0.005-0.2.

[0023] Preferably, the mass concentration of the aqueous LiOH solution is 10-50 g / L.

[0024] The molar ratio of LiOH to the Ni 0.5 Mn 1.5 (OH)4 precursor in the aqueous LiOH solution is 0.01-0.2.

[0025] Preferably, the temperature of the drying in step C) is 80-120℃, and the time of the drying in step C) is 6-24 hours.

[0026] Preferably, the P-coated Ni 0.5 Mn 1.5 The thickness of the coating layer in the (OH)4 precursor is 0.1-50nm.

[0027] Preferably, the temperature of the sintering in step D) is 600-1000℃, and the time of the sintering in step D) is 6-20 hours.

[0028] Preferably, after the sintering, the temperature is decreased to the annealing temperature at a rate of 0.2-1℃ / min, the annealing temperature is 600-700℃, and the annealing time is 4-10h.

[0029] The present application provides a high-voltage nickel-manganese positive electrode material, with the chemical formula LiNi 0.5-a Mn 1.5-b X c P d O4 formula I, wherein 0≤a≤0.2, 0≤b≤0.2, 0<c≤0.1, 0<d≤0.1; wherein, X is one or more of W, Ta, Ru, Mo, Te, Mg, Nb, V, Sr, Zr, Co, Ti, Cu, Cr, Si, Sc, Y, Cu, Zn, Fe, Al, B; the doping rate of P in the high-voltage nickel-manganese positive electrode material is 30-95%, and the volume V p The volume V0 of the region without P doping satisfies the relationship shown in formula II: The high-voltage nickel-manganese positive electrode material in the present application has high specific capacity, excellent rate performance and cycle performance, and the initial efficiency can reach more than 91% at a discharge rate of 0.1C. The initial capacity is higher than 134mAh / g at a discharge rate of 1C. The initial capacity is higher than 131mAh / g at a discharge rate of 2C, and the capacity retention rate is greater than 91% after 100 cycles. The initial capacity can reach 115mAh / g at a discharge rate of 3C.

[0030] The application also provides a preparation method of the high-voltage nickel-manganese positive electrode material, which adopts a wet P coating scheme, and P sources exist in the solution in an atomic manner, P is not easy to gather during precipitation, and a uniform coating thin layer with a thickness of 0.1-50 nm can be formed on the surface of the precursor. During high-temperature sintering, P in the coating thin layer gradually penetrates into the inner surface of the positive electrode in an atomic diffusion manner, and a surface P-doped spinel lithium nickel-manganese oxide is obtained. Compared with dry doping, the P doping rate can be increased to 30-95%, and the doping effect is significantly improved. The new chemical bonds formed after surface P doping can stabilize the positive electrode surface structure to a greater extent, and better protect the material from the corrosion of the electrolyte. In addition, the P sources that are not doped into the inner surface are coated on the outer surface of the positive electrode, so that the material is prevented from directly contacting the electrolyte. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the provided drawings.

[0032] Figure 1 SEM image of the precursor coated in Example 1 of the present application;

[0033] Figure 2 P distribution diagram of the precursor coated in Example 1 of the present application;

[0034] Figure 3 SEM image of the positive electrode material in Example 1 of the present application;

[0035] Figure 4 SEM image of the precursor coated in Comparative Example 1 of the present application;

[0036] Figure 5 P distribution diagram of the precursor coated in Comparative Example 1 of the present application;

[0037] Figure 6 SEM image of the precursor coated in Example 2 of the present application;

[0038] Figure 7 P distribution diagram of the precursor coated in Example 2 of the present application;

[0039] Figure 8 SEM of the lithium nickel-manganese oxide positive electrode material prepared in Example 2 of the present application;

[0040] Figure 9 SEM image of the precursor coated in Example 3 of the present application;

[0041] Figure 10 SEM image of the precursor coated in Example 3 of the present application;

[0042] Figure 11 SEM image of the precursor coated in Example 4 of the present application;

[0043] Figure 12 P distribution map of the precursor coated in Example 4 of the present application;

[0044] Figure 13 SEM image of the precursor coated in Example 5 of the present application;

[0045] Figure 14 P distribution map of the precursor coated in Example 5 of the present application;

[0046] Figure 15 SEM image of the precursor coated in Comparative Example 2 of the present application;

[0047] Figure 16 P distribution map of the precursor coated in Comparative Example 2 of the present application;

[0048] Figure 17 SEM image of the precursor coated in Example 6 of the present application;

[0049] Figure 18 P distribution map of the precursor coated in Example 6 of the present application;

[0050] Figure 19 SEM image of the precursor coated in Example 7 of the present application;

[0051] Figure 20 P distribution map of the precursor coated in Example 7 of the present application;

[0052] Figure 21 SEM image of the lithium nickel manganese oxide cathode material prepared in Example 7 of the present application;

[0053] Figure 22 SEM image of the precursor coated in Example 8 of the present application;

[0054] Figure 23 P distribution map of the precursor coated in Example 8 of the present application;

[0055] Figure 24 SEM image of the lithium nickel manganese oxide cathode material prepared in Example 8 of the present application;

[0056] Figure 25 First charge-discharge curves of the cathode materials of the comparative examples and examples under the condition of being discharged;

[0057] Figure 26 Rate cycle diagrams of the cathode materials of the comparative examples and examples under the condition of being discharged at room temperature;

[0058] Figure 27 Structure diagram of P-coated nickel-manganese precursor in the application. DETAILED DESCRIPTION

[0059] The application provides a high-voltage nickel-manganese positive electrode material, which is of a chemical formula of LiNi 0.5-a Mn 1.5-b X c P d O4 formula I, wherein 0≤a≤0.2, more preferably 0.01≤a≤0.2; 0≤b≤0.2, more preferably 0.01≤b≤0.2; 0

[0060] X is one or more of W, Ta, Ru, Mo, Te, Mg, Nb, V, Sr, Zr, Co, Ti, Cu, Cr, Si, Sc, Y, Cu, Zn, Fe, Al, B;

[0061] The high-voltage nickel-manganese positive electrode material is doped by wet coating of a precursor with a P source, and the doping rate of P in the positive electrode material is preferably 30-95%, more preferably 45-95%, most preferably 60-95%, and most most preferably 75-95%.

[0062] In the application, the prepared positive electrode material has one or more of uniform octahedron morphology, truncated octahedron morphology and (similar) spherical morphology.

[0063] When the positive electrode material has the octahedron morphology, the volume V p and the volume V0 of the region without P doping satisfy the relationship shown in formula III:

[0064]

[0065] wherein V p =V 正八面体 -V0, V 正八面体 represents the total volume of the octahedron containing the P-doped region and the region without P doping, a is the edge length of the octahedron containing the P-doped region and the region without P doping, b is the edge length of the octahedron of the region without P doping. Therefore, formula III can also be expressed as

[0066] When the positive electrode material has the truncated octahedron morphology, wherein, V 正八面体represents the volume of a regular octahedron including the P-doped region and the non-P-doped region and completed after truncation, a is the edge length of the regular octahedron including the P-doped region and the non-P-doped region and completed after truncation; V 四角锥 represents the volume of a truncated cone including the P-doped region and the non-P-doped region, a' is the base length of the truncated cone including the P-doped region and the non-P-doped region, and h is the height of the truncated cone including the P-doped region; b is the edge length of the regular octahedron of the non-P-doped region completed after truncation; b' is the base length of the truncated cone of the non-P-doped region, and h' is the height of the truncated cone of the non-P-doped region. Therefore, formula IV can also be represented as

[0067] when the positive electrode is in a spherical or quasi-spherical morphology, wherein V p = V 圆 -V0, V 圆 represents the volume of a sphere including the P-doped region and the non-P-doped region, r is the radius of the sphere including the P-doped region and the non-P-doped region, r' is the radius of the sphere of the non-P-doped region. Therefore, formula V can also be represented as

[0068] In the present application, the tap density of the high-voltage nickel-manganese positive electrode material is 1.2-2.4 g / cm 3 , D50 is 4-12 μm, and BET is 0.2-0.7 m 2 / g.

[0069] The present application also provides a preparation method of a high-voltage nickel-manganese positive electrode material, comprising the following steps:

[0070] A) dissolving a P source and a Ni 0.5 Mn 1.5 (OH)4 precursor in water to obtain a suspension A;

[0071] B) optionally adding an aqueous LiOH solution to obtain a suspension B;

[0072] C) drying the suspension A or B to obtain a P element-coated Ni 0.5 Mn 1.5 (OH)4 precursor;

[0073] D) mixing a lithium source, an additive containing X, and the P element-coated Ni 0.5 Mn 1.5 (OH)4 precursor, and sintering to obtain a P surface-doped high-voltage nickel-manganese positive electrode material LiNi 0.5-a Mn1.5-b X c P d O4。

[0074] The present application disperses the P source and Ni 0.5 Mn 1.5 The precursor dispersion solution of (NH4)3PO4 is stirred uniformly in deionized water to obtain a suspension A of small precursor particles suspended in solution.

[0075] In the present application, the P source is one or more of NH4H2PO4, (NH4)2HPO4, (NH4)3PO4 and H3PO4; the mass concentration of the P source in the solution A is preferably 5-20 g / L, more preferably 10-15 g / L, such as 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L, 15 g / L, 16 g / L, 17 g / L, 18 g / L, 19 g / L, 20 g / L, preferably a range value with any of the above values as the upper or lower limit.

[0076] In the present application, the molar ratio of the P source to Ni 0.5 Mn 1.5 (OH)4 precursor is preferably 0.005-0.2, more preferably 0.01-0.1, such as 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, preferably a range value with any of the above values as the upper or lower limit.

[0077] After obtaining the suspension A, the present application can continue to stir the suspension A without adding any substance, and then dry; or add an aqueous LiOH solution to the suspension A to obtain a suspension B, continue to stir, and then dry.

[0078] In the present application, when the suspension A is dried, the dissolved P source will gradually precipitate and adsorb on the surface of the precursor. This principle can be understood as the physical adsorption between different substances, i.e. adsorption caused by van der Waals force. Because the specific surface area of the Ni 0.5 Mn 1.5 (OH)4 precursor is large, the contact surface with the solution is wide, and when the solvent evaporates, the P source can adhere to the surface of the precursor in the form of small particles to form a thin coating film, completing the coating of the P source.

[0079] In the present application, the aqueous LiOH solution is added to the suspension A, and different P sources will react with LiOH. The specific reaction equation is as follows:

[0080] ① NH4H2PO4+ LiOH→ Li3PO4↓+ H2O+ NH3↑;

[0081] ② (NH4)2HPO4+ LiOH→ Li3PO4↓+ H2O+ NH3↑;

[0082] ③ (NH4)3PO4+ LiOH→ Li3PO4↓+ H2O+ NH3↑;

[0083] ④ H3PO4+ LiOH→ Li3PO4↓+ H2O.

[0084] It can be seen that different P sources will finally generate Li3PO4. The principle of this method is essentially the same as the first principle, both of which rely on physical adsorption, but since the P source has been attached to the precursor surface in the form of precipitation before solvent evaporation, the process can be relatively simple by using the way of suction filtration and drying, the requirement for equipment is lower, and the P source is basically not wasted.

[0085] In the present application, the P source and the precursor are added first, and then the LiOH aqueous solution is added, so that the reaction precipitate is slowly precipitated out to coat the precursor. The mass concentration of the LiOH aqueous solution is preferably 10-50 g / L, more preferably 20-40 g / L, such as 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, preferably a range value with any of the above values as the upper limit or lower limit; the molar ratio of LiOH to Ni 0.5 Mn 1.5 (OH)4 precursor in the LiOH aqueous solution is preferably 0.01-0.2, more preferably 0.02-0.1, such as 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, preferably a range value with any of the above values as the upper limit or lower limit.

[0086] After obtaining the suspension A or B, the present application dries the suspension A or B to obtain the P-coated Ni 0.5 Mn 1.5 (OH)4 precursor.

[0087] In the present application, the temperature of the drying is preferably 80-120°C, more preferably 90-110°C, such as 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, preferably a range with any of the above-mentioned values as the upper or lower limit, and the time of the drying is preferably 6-24 hours, more preferably 10-18 hours. In the present application, the drying is preferably spray drying or suction filtration drying.

[0088] In the present application, the thickness of the P-coating layer is preferably 0.1-50 nm.

[0089] P-coated Ni 0.5 Mn 1.5 After the (OH)4precursor, the present application mixes it uniformly with a lithium source and an X-containing additive in stoichiometric ratio in formula I, sintering, annealing after sintering, to obtain a P-surface-doped high-voltage nickel-manganese positive electrode material LiNi 0.5-a Mn 1.5-b X c P d O4.

[0090] In the present application, the lithium source is preferably Li2CO3 and / or LiOH·H2O, and the X-containing additive is preferably a compound containing at least one element of W, Ta, Ru, Mo, Te, Mg, Nb, V, Sr, Zr, Co, Ti, Cu, Cr, Si, Sc, Y, Cu, Zn, Fe, Al and B.

[0091] In the present application, the sintering temperature is preferably 600-1000°C, more preferably 800-1000°C, such as 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, preferably a range with any of the above-mentioned values as the upper or lower limit, the sintering time is preferably 6-20h, more preferably 10-15h, and the heating rate of the sintering is preferably 1-10°C / min, more preferably 2-6°C / min, such as 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, preferably a range with any of the above-mentioned values as the upper or lower limit. In the present application, air is introduced during the sintering process, and the flow rate of the air is preferably 1-5L / min, more preferably 2-4L / min,

[0092] After sintering in the present application, it is cooled to the annealing temperature at a certain cooling rate, and then annealing is performed to obtain a P-surface-doped high-voltage nickel-manganese positive electrode material LiNi 0.5-a Mn 1.5-b X cP d O4.

[0093] In the present application, the annealing temperature is preferably 600-700℃, more preferably 650-700℃, such as 600℃, 610℃, 620℃, 630℃, 640℃, 650℃, 660℃, 670℃, 680℃, 690℃, 700℃, preferably a range with any of the above values as upper or lower limit; the holding time of the annealing is preferably 4-10h, more preferably 4-6h; the cooling rate after sintering is preferably 0.2-1℃ / min, more preferably 0.3-0.8℃ / min, such as 0.2℃ / min, 0.3℃ / min, 0.4℃ / min, 0.5℃ / min, 0.6℃ / min, 0.7℃ / min, 0.8℃ / min, 0.9℃ / min, 1.0℃ / min, preferably a range with any of the above values as upper or lower limit.

[0094] The present application provides a high-voltage nickel-manganese positive electrode material, chemical formula is LiNi 0.5-a Mn 1.5-b X c P d O4 formula I, wherein 0≤a≤0.2, 0≤b≤0.2, 0<c≤0.1, 0<d≤0.1; wherein, X is one or more of W, Ta, Ru, Mo, Te, Mg, Nb, V, Sr, Zr, Co, Ti, Cu, Cr, Si, Sc, Y, Cu, Zn, Fe, Al, B; the doping rate of P in the high-voltage nickel-manganese positive electrode material is 30-95%, the volume V p The volume V0 of the region without P doping satisfies the relationship shown in formula II: The high-voltage nickel-manganese positive electrode material in the present application is a spinel lithium nickel-manganese acid positive electrode material with high specific capacity, excellent rate performance and cycle performance. At a discharge rate of 0.1C, the initial efficiency can be above 91%; at a discharge rate of 1C, the initial capacity is higher than 134mAh / g; at a discharge rate of 2C, the initial capacity is higher than 131mAh / g, and the capacity retention rate after 100 cycles is greater than 91%; at a discharge rate of 3C, the initial capacity can reach 115mAh / g.

[0095] The application further provides a preparation method of the high-voltage nickel-manganese positive electrode material. The P coating layer is coated by a wet method, the P source exists in an atomic level in the solution, the P is not easy to gather during precipitation, and a uniform coating thin layer with a thickness of 0.1-50 nm can be formed on the surface of the precursor. During high-temperature sintering, the P in the coating thin layer gradually penetrates into the inner surface of the positive electrode in an atomic diffusion manner, and the surface P-doped spinel lithium nickel-manganese oxide is obtained. Compared with dry doping, the P doping rate can be increased to 30-95 %, and the doping effect is significantly improved. The new chemical bonds formed after the surface P doping can stabilize the positive electrode surface structure to a greater extent, and the material is better protected from the corrosion of the electrolyte. In addition, the P source not doped into the inner surface is coated on the outer surface of the positive electrode, so that the material is prevented from directly contacting the electrolyte.

[0096] In order to further illustrate the application, the high-voltage nickel-manganese positive electrode material and the preparation method thereof provided by the application are described in detail below with reference to the examples, but it should not be understood as limiting the protection scope of the application.

[0097] Example 1

[0098] (1) 2.25 g of NH4H2PO4 and 200 g of Ni 0.5 Mn 1.5 (OH)4 precursor are added into 200 ml of deionized water, and continuous stirring is performed until the suspension becomes a uniform viscous suspension;

[0099] (2) The suspension obtained in step (1) is spray dried at 120 ℃ to obtain a P-coated Ni 0.5 Mn 1.5 (OH)4 precursor;

[0100] (3) Li2CO3, Ta2O5 and the above precursor are uniformly mixed according to a molar ratio of 0.51:0.005:1, loaded into a boat, and sintered in an air atmosphere, with a flow rate of 3 L / min, a temperature rising rate of 3 ℃ / min, 950 ℃ constant temperature for 10 h, cooling to 680 ℃ at a rate of 0.5 ℃ / min, constant temperature for 4 h, and natural cooling, to obtain a surface P-doped lithium nickel-manganese oxide positive electrode material.

[0101] The P content in the P-coated Ni 0.5 Mn 1.5 (OH)4 precursor prepared in this example 1 is shown in Table 1, which is 2926 ppm, and no obvious loss occurs.

[0102] The P content in the P-coated Ni 0.5 Mn 1.5 (OH)4 precursor prepared in this example 1 is shown in Table 1, which is 2926 ppm, and no obvious loss occurs. Figure 1 and 2It can be seen that P is uniformly distributed on the surface of the precursor and no obvious aggregation phenomenon occurs.

[0103] The SEM of the lithium nickel manganese oxide anode material prepared in this example 1 is shown in the attached Figure 3 , which is a uniform octahedral structure.

[0104] The physicochemical properties of the lithium nickel manganese oxide anode material prepared in this example 1 are shown in Table 2 in the attached, the tap density is 1.90 g / cm 3 , the BET is 0.39 m 2 / g, and the D50 is 8.97 μm.

[0105] After the lithium nickel manganese oxide anode material prepared in this example 1 is assembled into a button cell, electrochemical performance detection is performed, and the 0.1C initial charge-discharge curve (attached Figure 25 ) and the cycle rate curve (attached Figure 26 ) of the material are obtained. As can be seen from the figures, the initial capacity of the anode material is 133.8 mAh / g at a 0.1C discharge rate, and the initial efficiency is 91.71%. The initial capacity is 136.4 mAh / g at a 1C discharge rate. The initial capacity is 134.3 mAh / g at a 2C discharge rate, and the capacity retention rate after 100 cycles is 92.41%. The initial capacity is 119 mAh / g at a 3C discharge rate.

[0106] Comparative Example 1

[0107] (1) 2.25 g of NH4H2PO4 and 200 g of Ni 0.5 Mn 1.5 (OH)4 precursor are dry mixed with a juicer to obtain a dry P-coated Ni 0.5 Mn 1.5 (OH)4 precursor, and then Li2CO3 and Ta2O5 are uniformly mixed with the above precursor at a molar ratio of 0.51:0.005:1, the boat is loaded, and the sintering conditions are the same as in Example 1.

[0108] The SEM and element P distribution of the dry mixed NH4H2PO4 and Ni 0.5 Mn 1.5 (OH)4 precursor in this comparative example 1 are shown in attached Figure 4 and attached Figure 5 . It can be seen that P is in the form of large particles and is not fully dispersed.

[0109] After the lithium nickel manganese oxide anode material prepared in this comparative example 1 is assembled into a button cell, electrochemical performance detection is performed, and the 0.1C initial charge-discharge curve (attached Figure 25 ) and the cycle rate curve (attached Figure 26). It can be seen from the figure that the initial capacity of the positive electrode material is 126.6 mAh / g at a discharge rate of 0.1C, and the initial efficiency is 87.49%. The initial capacity is 131.5 mAh / g at a discharge rate of 1C. The initial capacity is 126.7 mAh / g at a discharge rate of 2C, and the capacity retention rate after 100 cycles is 88.16%. The initial capacity is only 106.5 mAh / g at a discharge rate of 3C.

[0110] Example 2

[0111] (1) 2.58 g of (NH4)2HPO4 and 200 g of Ni 0.5 Mn 1.5 (OH)4 precursor were added to 300 ml of deionized water, and stirring was continued until it became a uniform viscous suspension;

[0112] (2) The suspension obtained in step (1) was spray dried at 110°C to obtain a P-coated Ni 0.5 Mn 1.5 (OH)4 precursor;

[0113] (3) Li2CO3, Nb2O5 and the above precursor were uniformly mixed in a molar ratio of 0.52:0.005:1, loaded into a boat, and sintered in an air atmosphere, with a flow rate of 2 L / min, a heating rate of 4°C / min, a constant temperature of 900°C for 12 h, and then cooled to 660°C at a rate of 0.6°C / min, and kept at this temperature for 6 h, and then naturally cooled to obtain a P-doped lithium nickel manganese oxide positive electrode material.

[0114] The P content in the P-coated Ni 0.5 Mn 1.5 (OH)4 precursor prepared in this Example 2 is shown in Table 1 in the appendix, which is 2842 ppm, and no significant loss has occurred.

[0115] The P-coated Ni 0.5 Mn 1.5 (OH)4 precursor prepared in this Example 2 is shown in Table 1 in the appendix, which is 2842 ppm, and no significant loss has occurred. Figure 6 and 7 It can be seen that the P is uniformly distributed on the surface of the precursor, and no significant aggregation phenomenon occurs.

[0116] The SEM of the lithium nickel manganese oxide positive electrode material prepared in this Example 2 is shown in Figure 2 in the appendix. Figure 8 , which is a spherical structure.

[0117] The physicochemical properties of the lithium nickel manganese oxide positive electrode material prepared in this Example 2 are shown in Table 2 in the appendix, with a tap density of 1.92 g / cm 3 , a BET of 0.34 m 2 / g, and a D50 of 8.14 μm.

[0118] The nickel-manganese lithium acid anode material prepared in this embodiment 2 was assembled into a button cell, and electrochemical performance detection was performed, obtaining the 0.1C initial charge-discharge curve (attached Figure 25 ) and the cycle rate curve (attached Figure 26 ) of the material. As can be seen from the figure, the initial capacity of the anode material at 0.1C discharge rate is 133.1 mAh / g, and the initial efficiency is 91.54%. At 1C discharge rate, the initial capacity is 136.4 mAh / g. At 2C discharge rate, the initial capacity is 134.6 mAh / g, and the capacity retention rate after 100 cycles is 91.38%. At 3C discharge rate, the initial capacity reaches 117.5 mAh / g.

[0119] Embodiment 3

[0120] (1) 2.92 g of (NH4)3PO4 and 200 g of Ni 0.5 Mn 1.5 (OH)4 precursor were added to 250 ml of deionized water, and stirring was continued until it became a uniform sticky suspension;

[0121] (2) The suspension obtained in step (1) was spray dried at 100°C to obtain a P-coated Ni 0.5 Mn 1.5 (OH)4 precursor;

[0122] (4) LiOH, Ta2O5 and the above precursor were uniformly mixed in a molar ratio of 1.06:0.005:1, loaded into a boat, and sintered in an air atmosphere, with a flow rate of 4 L / min, a heating rate of 5°C / min, a constant temperature of 850°C for 14 h, and then cooled to 650°C at a rate of 0.8°C / min, and kept at this temperature for 8 h, and then naturally cooled to obtain a P-doped lithium nickel-manganese acid anode material.

[0123] The P content in the P-coated Ni 0.5 Mn 1.5 (OH)4 precursor prepared in this embodiment 3 is 2895 ppm, and no significant loss has occurred.

[0124] The SEM and element P distribution of the P-coated Ni 0.5 Mn 1.5 (OH)4 precursor prepared in this embodiment 3 are shown in the attached Figure 9 and 10 , it can be seen that P is uniformly distributed on the surface of the precursor, and no significant aggregation phenomenon occurs.

[0125] The nickel-manganese lithium acid anode material prepared in this embodiment 3 was assembled into a button cell, and electrochemical performance detection was performed, obtaining the 0.1C initial charge-discharge curve (attached Figure 25 ) and the cycle rate curve (attached Figure 26As shown in the figure, the cathode material exhibits an initial capacity of 133.3 mAh / g and an initial efficiency of 91.11% at a discharge rate of 0.1C. At a discharge rate of 1C, the initial capacity is 135.9 mAh / g. At a discharge rate of 2C, the initial capacity is 134.2 mAh / g, with a capacity retention of 92.32% after 100 cycles. At a discharge rate of 3C, the initial capacity reaches 119.5 mAh / g.

[0126] Example 4

[0127] (1) Mix 2.25g of 85% H3PO4 and 200g of Ni 0.5 Mn 1.5 Add 150 ml of deionized water to the (OH)4 precursor and stir continuously until it becomes a uniform and viscous suspension.

[0128] (2) The suspension obtained in step (1) is spray-dried at 90°C to obtain P-coated Ni. 0.5 Mn 1.5 (OH)4 precursor;

[0129] (4) LiOH, Nb2O5 and the above precursor were uniformly mixed in a molar ratio of 1.08:0.005:1, loaded into a boat, and sintered in an air atmosphere at a flow rate of 5 L / min, a heating rate of 7 °C / min, and a constant temperature of 800 °C for 16 h. Then, the mixture was cooled to 630 °C at a rate of 1 °C / min, held for 10 h, and allowed to cool naturally to obtain a P-doped lithium nickel manganese oxide cathode material.

[0130] The P-coated Ni prepared in Example 4 0.5 Mn 1.5 The P content in the (OH)4 precursor is shown in Appendix Table 1, which is 2701 ppm, indicating no significant loss.

[0131] The P-coated Ni prepared in Example 4 0.5 Mn 1.5 SEM images of the (OH)4 precursor and the elemental P distribution are shown in the appendix. Figure 11 and 12 It can be seen that P is evenly distributed on the surface of the precursor and no obvious aggregation phenomenon is observed.

[0132] The lithium nickel manganese oxide cathode material prepared in Example 4 was assembled into a coin cell, and its electrochemical performance was tested to obtain the 0.1C first charge-discharge curve of the material (see attached figure). Figure 25 ) and cycle ratio curve (attached) Figure 26As shown in the figure, the cathode material exhibits an initial capacity of 131.2 mAh / g and an initial efficiency of 92.01% at a discharge rate of 0.1C. At a discharge rate of 1C, the initial capacity is 135.1 mAh / g. At a discharge rate of 2C, the initial capacity is 132.2 mAh / g, with a capacity retention of 91.60% after 100 cycles. At a discharge rate of 3C, the initial capacity reaches 115.6 mAh / g.

[0133] Example 5

[0134] (1) Mix 2.25g of NH4H2PO4 and 200g of Ni 0.5 Mn 1.5 Add 200ml of deionized water to the (OH)4 precursor and stir continuously until it becomes a uniform and viscous suspension.

[0135] (2) Add 50 ml of 2.82% LiOH aqueous solution (in small amounts several times) to the suspension in step (1), stirring continuously during the addition process. After the addition is complete, stir for another 5 min to ensure uniform reaction. Vacuum filter and dry at 120℃ for 6 h to obtain P-coated Ni. 0.5 Mn 1.5 (OH)4 precursor;

[0136] (3) Same as Example 1.

[0137] The P-coated Ni prepared in Example 5 0.5 Mn 1.5 The P content in the (OH)4 precursor is shown in Appendix Table 1, which is 2906 ppm, indicating no significant loss.

[0138] The P-coated Ni prepared in Example 5 0.5 Mn 1.5 SEM images of the (OH)4 precursor and the elemental P distribution are shown in the appendix. Figure 13 and 14 It can be seen that P is evenly distributed on the surface of the precursor and no obvious aggregation phenomenon is observed.

[0139] The lithium nickel manganese oxide cathode material prepared in Example 5 was assembled into a coin cell, and its electrochemical performance was tested to obtain the 0.1C first charge-discharge curve of the material (see attached figure). Figure 25 ) and cycle ratio curve (attached) Figure 26 As shown in the figure, the cathode material exhibits an initial capacity of 131.8 mAh / g and an initial efficiency of 92.23% at a discharge rate of 0.1C. At a discharge rate of 1C, the initial capacity is 135.1 mAh / g. At a discharge rate of 2C, the initial capacity is 133.7 mAh / g, with a capacity retention of 92.52% after 100 cycles. At a discharge rate of 3C, the initial capacity reaches 119.1 mAh / g.

[0140] Comparative Example 2

[0141] (1) Add 2.25g NH4H2PO4 and 200g Ni 0.5 Mn 1.5 Add (OH)4 precursor and 2.47g LiOH·H2O to 200ml deionized water and stir continuously until a uniform viscous suspension is formed.

[0142] (2) The suspension obtained in step (1) was vacuum filtered and dried at 120°C for 6 hours to obtain P-coated Ni. 0.5 Mn 1.5 (OH)4 precursor;

[0143] (3) Same as Example 1.

[0144] In Comparative Example 2, NH4H2PO4 and Ni 0.5 Mn 1.5 SEM images and elemental P distribution of the (OH)4 precursor and LiOH·H2O after drying are shown in the appendix. Figure 15 and attached Figure 16 It can be seen that P is unevenly distributed on the surface of the precursor, and obvious aggregation occurs.

[0145] The lithium nickel manganese oxide cathode material prepared in Comparative Example 2 was assembled into a coin cell, and its electrochemical performance was tested. The 0.1C first charge-discharge curve of the material was obtained (see attached figure). Figure 25 ) and cycle ratio curve (attached) Figure 26 As shown in the figure, the cathode material has an initial capacity of 130.4 mAh / g and an initial efficiency of 89.75% at a discharge rate of 0.1C; an initial capacity of 129.5 mAh / g at a discharge rate of 1C; an initial capacity of 125.5 mAh / g at a discharge rate of 2C, with a capacity retention of 89.40% after 100 cycles; and an initial capacity of 106.1 mAh / g at a discharge rate of 3C.

[0146] Example 6

[0147] (1) Mix 2.58g of (NH4)2HPO4 and 200g of Ni 0.5 Mn 1.5 Add (OH)4 to 300ml of deionized water and stir continuously until it becomes a uniform and viscous suspension.

[0148] (2) Add 30 ml of 4.70% LiOH aqueous solution (in small amounts several times) to the suspension in step (1), stirring continuously during the addition process. After the addition is complete, stir for another 8 min to ensure uniform reaction. Vacuum filter and dry at 110℃ for 10 h to obtain P-coated Ni. 0.5 Mn 1.5(OH)4 precursor;

[0149] (3) Same as Example 2.

[0150] The P-coated Ni prepared in Example 6 0.5 Mn 1.5 The P content in the (OH)4 precursor is shown in Appendix Table 1, which is 2958 ppm, indicating no significant loss.

[0151] The P-coated Ni prepared in Example 6 0.5 Mn 1.5 SEM images of the (OH)4 precursor and the elemental P distribution are shown in the appendix. Figure 17 and 18 It can be seen that P is evenly distributed on the surface of the precursor and no obvious aggregation phenomenon is observed.

[0152] The lithium nickel manganese oxide cathode material prepared in Example 6 was assembled into a coin cell, and its electrochemical performance was tested to obtain the 0.1C first charge-discharge curve of the material (see attached figure). Figure 25 ) and cycle ratio curve (attached) Figure 26 As shown in the figure, the cathode material exhibits an initial capacity of 133.3 mAh / g and an initial efficiency of 92.51% at a discharge rate of 0.1C. At a discharge rate of 1C, the initial capacity is 135.8 mAh / g. At a discharge rate of 2C, the initial capacity is 133.2 mAh / g, with a capacity retention of 92.57% after 100 cycles. At a discharge rate of 3C, the initial capacity reaches 118.7 mAh / g.

[0153] Example 7

[0154] (1) Mix 2.92g (NH4)3PO4 and 200g Ni 0.5 Mn 1.5 Add (OH)4 to 250ml of deionized water and stir continuously until it becomes a uniform and viscous suspension.

[0155] (2) Add 80 ml of 1.76% LiOH aqueous solution (in small amounts several times) to the suspension in step (1), stirring continuously during the addition process. After the addition is complete, stir for another 5 min to ensure uniform reaction. Vacuum filter and dry at 100℃ for 15 h to obtain P-coated Ni. 0.5 Mn 1.5 (OH)4 precursor;

[0156] (3) LiOH, SrO and the precursor above were uniformly mixed in a molar ratio of 1.06:0.005:1, loaded into a boat, and sintered in an air atmosphere, with a flow rate of 4 L / min, a heating rate of 5°C / min, constant temperature at 850°C for 14 h, cooling to 650°C at a rate of 0.8°C / min, and constant temperature at 650°C for 8 h, and natural cooling, to obtain a P-doped lithium nickel manganese oxide positive electrode material.

[0157] The P-coated Ni prepared in Example 7 0.5 Mn 1.5 The P content in the (OH)4precursor was 2764 ppm, and no significant loss occurred.

[0158] The P-coated Ni prepared in Example 7 0.5 Mn 1.5 The SEM and P element distribution of the (OH)4precursor are shown in the accompanying Figure 19 and 20 It can be seen that P is uniformly distributed on the surface of the precursor, and no significant aggregation occurs.

[0159] The SEM of the lithium nickel manganese oxide positive electrode material prepared in Example 7 is shown in the accompanying Figure 21 , which is a truncated octahedral structure.

[0160] The physicochemical properties of the lithium nickel manganese oxide positive electrode material prepared in Example 7 are shown in the accompanying Table 2, with a tap density of 1.83 g / cm 3 , a BET of 0.41 m 2 / g, and a D50 of 7.92 μm.

[0161] The lithium nickel manganese oxide positive electrode material prepared in Example 7 was assembled into a button cell, and electrochemical performance testing was performed, to obtain the 0.1C initial charge-discharge curve (the accompanying Figure 25 ) and the cycle rate curve (the accompanying Figure 26 ). As can be seen from the figures, the initial capacity of the positive electrode material at a 0.1C discharge rate was 132.0 mAh / g, and the initial efficiency was 91.41%. The initial capacity at a 1C discharge rate was 135.1 mAh / g. The initial capacity at a 2C discharge rate was 133.0 mAh / g, and the capacity retention rate after 100 cycles was 92.63%. The initial capacity at a 3C discharge rate was 118.7 mAh / g.

[0162] Example 8

[0163] (1) 2.25 g of H3PO4with a concentration of 85% and 200 g of Ni 0.5 Mn 1.5 (OH)4were added to 150 ml of deionized water, and stirring was continued until a uniform viscous suspension was obtained;

[0164] (2) To the suspension in step (1), 100 ml of LiOH aqueous solution with a concentration of 1.41% is added (in small amounts and multiple times), stirring is continued during the addition, and after the addition is completed, stirring is continued for 5 min to make the reaction uniform, vacuum filtration is performed, and drying is performed at 90°C for 20 h to obtain P-coated Ni 0.5 Mn 1.5 (OH)4precursor;

[0165] (3) LiOH, Nb2O5, and WO3 are uniformly mixed with the above precursor according to a molar ratio of 1.08:0.005:1, a boat is loaded, sintering is performed in an air atmosphere, the flow rate is 5 L / min, the temperature increasing rate is 7°C / min, the temperature is kept at 800°C for 16 h, then the temperature is cooled to 630°C at a rate of 1°C / min, and the temperature is kept at 630°C for 10 h, and then natural cooling is performed, to obtain a P-doped lithium nickel manganese oxide positive electrode material.

[0166] The P-coated Ni 0.5 Mn 1.5 in the precursor prepared in this embodiment 8 has a P content of 2904 ppm, and no obvious loss occurs.

[0167] The P-coated Ni 0.5 Mn 1.5 in the precursor prepared in this embodiment 8 has a P content of 2904 ppm, and no obvious loss occurs. Figure 22 and 23 It can be seen that P is uniformly distributed on the surface of the precursor, and no obvious aggregation phenomenon occurs.

[0168] The SEM of the lithium nickel manganese oxide positive electrode material prepared in this embodiment 8 is shown in the accompanying Figure 24 , which is a spherical structure.

[0169] The physicochemical properties of the lithium nickel manganese oxide positive electrode material prepared in this embodiment 8 are shown in Table 2 in the accompanying drawings, the tap density is 1.66 g / cm 3 , the BET is 0.51 m 2 / g, and the D50 is 6.80 μm.

[0170] After the lithium nickel manganese oxide positive electrode material prepared in this embodiment 8 is assembled into a button cell, electrochemical performance detection is performed, and the 0.1C initial charge-discharge curve (attached Figure 25 ) and the cycle rate curve (attached Figure 26 ) of the material are obtained. As can be seen from the figures, the initial capacity of the positive electrode material is 133.3 mAh / g at a 0.1C discharge rate, and the initial efficiency is 92.83%. The initial capacity is 134.9 mAh / g at a 1C discharge rate. The initial capacity is 131.1 mAh / g at a 2C discharge rate, and the capacity retention rate is 92.37% after 100 cycles. The initial capacity reaches 116.4 mAh / g at a 3C discharge rate.

[0171] Table 1 P content in the coated precursor of Examples 1 to 8 (theoretical content: 3000 ppm)

[0172] Example P element content / ppm Example 1 2926 Example 2 2842 Example 3 2895 Example 4 2701 Example 5 2906 Example 6 2958 Example 7 2764 Example 8 2904

[0173] Table 2 Electrode physicochemical properties of Examples 1, 2, 7 and 8

[0174] Tap density (g / cm3) 3 )] BET(m 2 / g) D50 D10 D90 Example 1 1.90 0.39 8.97 4.66 16.23 Example 2 1.94 0.43 9.03 4.60 16.62 Example 7 1.83 0.41 7.92 3.87 14.96 Example 8 1.66 0.51 6.80 3.36 12.64

[0175] The above only is the preferred embodiment of the present application, should point out, for the ordinary skilled in the art, without departing from the principles of the present application, can also make a number of improvements and refinements, these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A high-voltage nickel-manganese cathode material, wherein the high-voltage nickel-manganese cathode material is a surface-doped P-doped spinel nickel-manganese cathode material with the chemical formula LiNi. 0.5-a Mn 1.5-b X c P d Formula I of O4, where 0≤a≤0.2, 0≤b≤0.2, 0<c≤0.1, 0<d≤0.1; in, X is one or more of W, Ta, Ru, Mo, Te, Mg, Nb, V, Sr, Zr, Co, Ti, Cu, Cr, Si, Sc, Y, Zn, Fe, Al, and B; The tap density of the high-voltage nickel-manganese cathode material is 1.2~2.4 g / cm³. 3 D50 is 4~12μm, BET is 0.2~0.7m. 2 / g; In the high-voltage nickel-manganese cathode material, the doping rate of P is 30-95%, and the volume of the P-doped region is V. p The volume V0 of the undoped region satisfies the relationship shown in Equation II: 1×10 -5 ≤ ≤9.5×10 -1 Formula II; The high-voltage nickel-manganese cathode material has at least one of the following morphologies: regular octahedron, truncated octahedron, spherical, and near-spherical. When the high-voltage nickel-manganese cathode material has an octahedral morphology, V p V0 satisfies the relationship shown in Equation III: 1×10 -5 ≤ ≤3.5×10 -1 Formula III; When the high-voltage nickel-manganese cathode material has a truncated octahedral morphology, V p V0 satisfies the relationship shown in equation IV: 5×10 -5 ≤ ≤1×10 -1 Formula IV; When the high-voltage nickel-manganese cathode material has a spherical or near-spherical morphology, V p V0 satisfies the relationship shown in equation V: 4×10 -5 ≤ ≤9.5×10 -1 Formula V.

2. The method for preparing the high-voltage nickel-manganese cathode material as described in claim 1, comprising the following steps: A) Combine the P source and Ni 0.5 Mn 1.5 (OH)4 precursor is added to deionized water to obtain suspension A; B) Optionally, add LiOH aqueous solution to obtain suspension B; C) Dry suspension A or B to obtain P-coated Ni. 0.5 Mn 1.5 (OH)4 precursor; D) Ni coated with lithium source, X-containing additives and P element. 0.5 Mn 1.5 (OH)4 precursor is mixed and sintered to obtain high-voltage nickel-manganese cathode material LiNi. 0.5-a Mn 1.5-b X c P d O4.

3. The preparation method according to claim 2, characterized in that, The P source is one or more of NH4H2PO4, (NH4)2HPO4, (NH4)3PO4, and H3PO4; The mass concentration of the P source in the suspension A is 5~20 g / L; The P source and Ni 0.5 Mn 1.5 The molar ratio of (OH)4 precursor is 0.005~0.

2.

4. The preparation method according to claim 2, characterized in that, The mass concentration of the LiOH aqueous solution is 10~50 g / L; LiOH and Ni in LiOH aqueous solution 0.5 Mn 1.5 The molar ratio of (OH)4 precursor is 0.01~0.

2.

5. The preparation method according to claim 2, characterized in that, The drying temperature in step C) is 80~120℃, and the drying time in step C) is 6~24 hours.

6. The preparation method according to claim 2, characterized in that, The Ni coated with P element 0.5 Mn 1.5 In the (OH)4 precursor, the thickness of the coating layer is 0.1~50 nm.

7. The preparation method according to claim 2, characterized in that, The sintering temperature in step D) is 600~1000℃, and the sintering time in step D) is 6~20 hours.

8. The preparation method according to any one of claims 2 to 7, characterized in that, After sintering, the temperature is lowered to the annealing temperature at a rate of 0.2~1℃ / min for annealing. The annealing temperature is 600~700℃, and the annealing holding time is 4~10h.

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