Ternary co-doped nickel-manganese-based precursor, positive electrode material, preparation thereof and battery

Abstract

The invention provides a ternary co-doped nickel-manganese-based precursor, a positive electrode material, preparation of the ternary co-doped nickel-manganese-based precursor and a battery, the nickel-manganese-based precursor comprises a doping element F, and further comprises a doping element M and a doping element N which are different from each other, and the doping element M and the doping element N respectively and independently comprise any one of Mg, Mo, Nb, Ga, B, Pb, W, Nb, Ti, Ce, V, Al, La, Zr and Bi. According to the invention, the nickel-manganese-based precursor is doped with the doping element F, the doping element M and the doping element N, the positive electrode material prepared from the nickel-manganese-based precursor has relatively good structural stability under high voltage, and an irreversible oxygen releasing agent and capacity fading are greatly improved; the lithium ion battery prepared from the obtained positive electrode material has relatively high specific discharge capacity and relatively good cycling stability on the surface under a high-voltage condition.

Description

Technical Field

[0001] The present invention belongs to the technical field of positive electrode materials, and relates to a ternary co-doped nickel-manganese-based precursor, and in particular to a ternary co-doped nickel-manganese-based precursor, a positive electrode material, and a preparation method thereof and a battery. Background Art

[0002] Nickel-manganese-based precursors are usually composed of composite hydroxides of Mn and transition metals such as Ni, in which the Mn content is high and the content of other transition metals is moderate. They are intermediates for preparing nickel-manganese-based positive electrode materials. Nickel-manganese-based positive electrode materials have unique chemical composition and structural design. They are the key foundation for achieving high energy density and long cycle life battery performance. They are widely used in the development of positive electrode materials for the next generation of high specific capacity lithium-ion batteries.

[0003] However, conventional nickel-manganese-based cathode materials suffer from structural instability, irreversible oxygen release, and rapid capacity decay at high voltages. Existing technologies often employ single anion or cation doping (e.g., Mg, Al, Ti, and S), as well as surface coating (e.g., LiNbO3 coating, Al2O3 coating, etc.) to improve the cycling stability and electrochemical performance of nickel-manganese-based cathode materials.

[0004] CN119833606A discloses a manganese-based composite cathode material, its preparation method, and its application. This manganese-based composite cathode material has a core-shell structure, wherein the core of the core-shell structure is a lithium manganate material, and the outer shell is a lithium-rich manganese-based cathode material. However, when using lithium-ion batteries made with this manganese-based composite cathode material under high voltage conditions, repeated insertion and extraction of lithium ions causes lattice expansion and contraction, which can easily lead to mechanical stress accumulation in the coating of the manganese-based composite cathode material, resulting in cracks and ultimately battery capacity degradation.

[0005] CN116534916A discloses a fluorine-aluminum dual-doped lithium-rich manganese-based positive electrode material, its preparation method and application. The preparation method of the fluorine-aluminum dual-doped lithium-rich manganese-based positive electrode material disclosed in this patent document includes the following steps: S1: dissolving metal salts of lithium, manganese, cobalt, nickel and ammonium fluoroaluminate in a solvent to prepare a mixed solution; S2: mixing and stirring the mixed solution with an oxalic acid solution, and then drying to prepare a precursor; S3: pre-calcining the precursor, grinding it after pre-calcining to prepare a mixture; S4: sintering the mixture to prepare a fluorine-aluminum dual-doped lithium-rich manganese-based positive electrode material. However, the battery prepared with the fluorine-aluminum dual-doped lithium-rich manganese-based positive electrode material disclosed in this patent document also has insufficient electrochemical performance under high voltage conditions.

[0006] Nickel-manganese-based precursors disclosed in the prior art all have certain drawbacks. The resulting cathode materials suffer from structural instability, irreversible oxygen release, and rapid capacity decay at high voltages. Consequently, lithium-ion batteries using these cathode materials exhibit insufficient electrochemical performance at high voltages. Therefore, the development and design of novel ternary co-doped nickel-manganese-based precursors, cathode materials, and their preparation and battery applications are crucial. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a ternary co-doped nickel-manganese-based precursor, a positive electrode material, and a preparation thereof and a battery. In the present invention, the nickel-manganese-based precursor is doped with three elements, namely, doping element F, doping element M and doping element N. The positive electrode material prepared from the nickel-manganese-based precursor has good structural stability under high voltage, and the irreversible oxygen release agent and capacity attenuation are greatly improved; the lithium-ion battery prepared from the obtained positive electrode material exhibits a high discharge specific capacity and good cycle stability under high voltage conditions.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a ternary co-doped nickel-manganese-based precursor, which contains a doping element F and also contains a doping element M and a doping element N that are different from each other, and the doping element M and the doping element N independently include any one of Mg, Mo, Nb, Ga, B, Pb, W, Nb, Ti, Ce, V, Al, La, Zr or Bi.

[0010] In the prior art, when modifying nickel-manganese-based precursors, single element doping is usually adopted. However, single element doping is difficult to take into account both the crystal structure stability and electronic conductivity of the nickel-manganese-based precursors.

[0011] In the present invention, a nickel-manganese-based precursor is doped with three elements, namely, doping element F, doping element M and doping element N. After the positive electrode material is prepared using the nickel-manganese-based precursor, the Li ion site, transition metal ion site and oxygen full lattice site in the positive electrode material are partially and synergistically replaced by the three elements, namely, doping element F, doping element M and doping element N; wherein, the doping element F replaces O2- to form a strong F-transition metal bond, thereby inhibiting oxygen release; the doping element M and the doping element N achieve the widening of the Li interlayer spacing, thereby enhancing the diffusion rate of lithium ions, and shortening the Mn-O bond length, thereby stabilizing the transition metal layer; therefore, the positive electrode material prepared using the nickel-manganese-based precursor has good structural stability under high voltage, and the irreversible oxygen release agent and capacity attenuation are greatly improved; the lithium ion battery prepared using the obtained positive electrode material exhibits a higher discharge specific capacity and better cycle stability under high voltage conditions.

[0012] Preferably, the content of the doping element F in the nickel-manganese-based precursor gradually decreases from the surface to the center of the nickel-manganese-based precursor.

[0013] In the existing technology, the modification of nickel-manganese-based precursors is mainly concentrated on the surface of the nickel-manganese-based precursors. The problems of oxygen release and structural collapse are not solved from the root from the inside. There is a lack of in-depth regulation of the specific position of the doping elements in the crystal lattice and the synergistic mechanism, which can easily cause excessive passivation of the material surface and hinder the transmission of ions.

[0014] In the present invention, the nickel-manganese-based precursor has a fluorination distribution from high fluorine concentration on the surface to low fluorine concentration in the bulk phase, and the fluorine concentration gradually decreases from the surface to the core of the nickel-manganese-based precursor. The positive electrode material prepared using the nickel-manganese-based precursor is not easily corroded by the electrolyte, can promote the formation of a dense CEI layer, and reduce the ion transmission resistance.

[0015] Preferably, the nickel-manganese-based precursor includes oxygen element, and the molar ratio of the oxygen element to the doping element F is (9-10):(0.1-1), for example, it can be 9:0.1, 9.2:0.2, 9.4:0.3, 9.6:0.4, 9.8:0.5, 10:0.6, 10:0.7, 10:0.8, 10:0.9 or 10:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] Preferably, the molar ratio between the element Mn and the element Ni in the nickel-manganese-based precursor is (0.55-0.8):(0.1-0.25), for example, it can be 0.55:0.1, 0.58:0.12, 0.61:0.14, 0.64:0.16, 0.67:0.18, 0.70:0.20, 0.73:0.22, 0.76:0.24 or 0.80:0.25, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] Preferably, the doping element M is element Mg.

[0018] Preferably, in the nickel-manganese-based precursor, the molar ratio of element Mn to doping element M is (0.55-0.8):(0.01-0.1), for example, it can be 0.55:0.01, 0.58:0.02, 0.61:0.03, 0.64:0.04, 0.67:0.05, 0.70:0.06, 0.73:0.07, 0.76:0.08, 0.79:0.09 or 0.80:0.10, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0019] Preferably, the doping element N is element Nb.

[0020] Preferably, in the nickel-manganese-based precursor, the molar ratio of element Mn to doping element N is (0.55-0.8):(0.01-0.34), for example, it can be 0.55:0.01, 0.57:0.05, 0.59:0.09, 0.61:0.13, 0.63:0.17, 0.65:0.21, 0.67:0.25, 0.69:0.29, 0.71:0.33 or 0.80:0.34, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0021] Preferably, the D50 particle size of the nickel-manganese-based precursor is 5 to 14 μm, for example, it can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm or 14 μm, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0022] In a second aspect, the present invention provides a method for preparing the nickel-manganese-based precursor according to the first aspect, the preparation method comprising:

[0023] (1) using manganese salt, nickel salt, M salt, N salt, precipitant, complexing agent and solvent as raw materials, and preparing a precipitate by wet coprecipitation;

[0024] (2) mixing a fluoride salt solution with the precipitate obtained in step (1), and then performing heat treatment to obtain the nickel-manganese-based precursor.

[0025] In the preparation method of the present invention, the precipitate obtained in step (1) is prepared by wet co-precipitation. By controlling the reaction temperature, reaction time, reaction atmosphere, pH of the reaction solution, nickel-manganese ion concentration of the reaction solution, complexing agent type, complexing agent concentration, doping metal type, and doping metal concentration in the wet co-precipitation, the particle size and morphology of the nickel-manganese-based precursor can be effectively controlled; therefore, the preparation method has high controllability when preparing the nickel-manganese-based precursor.

[0026] In the preparation method of the present invention, the precipitate obtained in step (1) is mixed with a fluoride salt solution and then subjected to heat treatment, so that the fluorine element in the fluoride salt replaces the O2- site in the precipitate obtained in step (1), thereby obtaining a nickel-manganese-based precursor in which the fluorine concentration gradually decreases from the surface to the core.

[0027] Preferably, the wet co-precipitation in step (1) comprises: firstly adding a manganese salt, a nickel salt, an M salt, an N salt, a precipitant and a complexing agent into a solvent respectively to obtain a manganese salt solution, a nickel salt solution, an M salt solution, an N salt solution, a precipitant solution and a complexing agent solution; then adding the obtained manganese salt solution, nickel salt solution, M salt solution, N salt solution, precipitant solution and complexing agent solution into a reaction base liquid in parallel to form a reaction solution, and performing a co-precipitation reaction in the reaction solution to obtain a precipitate.

[0028] Preferably, the manganese salt in step (1) comprises any one of sulfate, carbonate, chloride or nitrate, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of sulfate and carbonate, a combination of chloride and nitrate, a combination of carbonate and chloride, a combination of nitrate and sulfate, or a combination of sulfate, carbonate and chloride.

[0029] Preferably, the concentration of manganese salt in the manganese salt solution is 25 to 70 g / L, for example, it can be 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, 55 g / L, 60 g / L, 65 g / L or 70 g / L, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0030] Preferably, the addition rate of the manganese salt solution during the parallel addition is 20 to 50 L / h, for example, 20 L / h, 25 L / h, 30 L / h, 35 L / h, 40 L / h, 45 L / h or 50 L / h, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0031] Preferably, the nickel salt in step (1) comprises any one of sulfate, carbonate, chloride or nitrate, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of sulfate and carbonate, a combination of chloride and nitrate, a combination of carbonate and chloride, a combination of nitrate and sulfate, or a combination of sulfate, carbonate and chloride.

[0032] Preferably, the concentration of nickel salt in the nickel salt solution is 25 to 70 g / L, for example, it can be 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, 55 g / L, 60 g / L, 65 g / L or 70 g / L, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0033] Preferably, the addition rate of the nickel salt solution during the parallel addition is 20 to 50 L / h, for example, 20 L / h, 25 L / h, 30 L / h, 35 L / h, 40 L / h, 45 L / h or 50 L / h, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0034] Preferably, the M salt in step (1) comprises any one or a combination of at least two of sulfate, carbonate, chloride or nitrate. Typical but non-limiting combinations include a combination of sulfate and carbonate, a combination of chloride and nitrate, a combination of carbonate and chloride, a combination of nitrate and sulfate, or a combination of sulfate, carbonate and chloride.

[0035] Preferably, the concentration of M salt in the M salt solution is 25 to 70 g / L, for example, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, 55 g / L, 60 g / L, 65 g / L or 70 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0036] Preferably, the addition rate of the M salt solution during the parallel addition is 20 to 50 L / h, for example, 20 L / h, 25 L / h, 30 L / h, 35 L / h, 40 L / h, 45 L / h or 50 L / h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0037] Preferably, the N salt in step (1) comprises any one of sulfate, carbonate, chloride, nitrate or oxalate, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of sulfate and carbonate, a combination of chloride and nitrate, a combination of carbonate and chloride, a combination of nitrate and sulfate, a combination of nitrate and oxalate, or a combination of sulfate, carbonate and chloride.

[0038] Preferably, the concentration of the N salt in the N salt solution is 25 to 70 g / L, for example, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, 55 g / L, 60 g / L, 65 g / L or 70 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0039] Preferably, the addition rate of the N salt solution during the parallel addition is 20 to 50 L / h, for example, 20 L / h, 25 L / h, 30 L / h, 35 L / h, 40 L / h, 45 L / h or 50 L / h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] Preferably, the precipitant in step (1) comprises any one or a combination of at least two of sodium hydroxide, tetramethylammonium hydroxide, urea or sodium carbonate. Typical but non-limiting combinations include a combination of sodium hydroxide and tetramethylammonium hydroxide, a combination of urea and sodium carbonate, a combination of tetramethylammonium hydroxide and urea, a combination of sodium carbonate and sodium hydroxide, or a combination of sodium hydroxide, tetramethylammonium hydroxide and urea.

[0041] Preferably, the mass concentration of the precipitant in the precipitant solution is 25 to 45 wt%, for example, it can be 25 wt%, 27 wt%, 29 wt%, 31 wt%, 33 wt%, 35 wt%, 37 wt%, 39 wt%, 41 wt%, 43 wt% or 45 wt%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0042] Preferably, the addition rate of the precipitant solution during the parallel addition is 10 to 20 L / h, for example, 10 L / h, 12 L / h, 14 L / h, 16 L / h, 18 L / h or 20 L / h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] Preferably, the complexing agent in step (1) comprises any one or a combination of at least two of tartaric acid, polyvinyl pyrrolidone, ammonia or ammonium bicarbonate. Typical but non-limiting combinations include a combination of tartaric acid and polyvinyl pyrrolidone, a combination of ammonia and ammonium bicarbonate, a combination of polyvinyl pyrrolidone and ammonia, a combination of ammonium bicarbonate and tartaric acid, or a combination of tartaric acid, polyvinyl pyrrolidone and ammonia.

[0044] Preferably, the mass concentration of the complexing agent in the complexing agent solution is 10 to 25 wt%, for example, it can be 10 wt%, 12 wt%, 14 wt%, 16 wt%, 18 wt%, 20 wt%, 22 wt%, 24 wt% or 25 wt%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0045] Preferably, the addition rate of the complexing agent solution during the parallel addition is 2 to 5 L / h, for example, 2 L / h, 2.5 L / h, 3 L / h, 3.5 L / h, 4 L / h, 4.5 L / h or 5 L / h, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0046] Preferably, the pH of the reaction base solution is 11-11.5, and the concentration of the complexing agent is 2-8 g / L.

[0047] In the present invention, the pH of the reaction base solution is 11 to 11.5, for example, 11.0, 11.1, 11.2, 11.3, 11.4 or 11.5, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0048] In the present invention, the complexing agent concentration of the reaction base solution is 2 to 8 g / L, for example, it can be 2 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L or 8 g / L, but is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable.

[0049] Preferably, the method for preparing the reaction base liquid comprises: adding a precipitant and a complexing agent into a solvent to obtain the reaction base liquid.

[0050] Preferably, in the coprecipitation reaction, the temperature of the reaction solution is controlled to be 45-70° C., the pH is 9-12, and the concentration of the complexing agent is 2-12 g / L.

[0051] In the present invention, in the coprecipitation reaction, the temperature of the reaction solution is controlled to be 45-70°C, for example, it can be 45°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C or 70°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0052] In the present invention, in the coprecipitation reaction, the complexing agent concentration of the reaction solution is controlled to be 2 to 12 g / L, for example, it can be 2 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L, 11 g / L or 12 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0053] Preferably, in the coprecipitation reaction, the molar ratio of Mn ions, Ni ions, M ions and N ions in the reaction solution is controlled to be (0.55-0.8):(0.1-0.25):(0.01-0.1):(0.01-0.34).

[0054] In the present invention, in the coprecipitation reaction, the molar ratio of Mn ions to Ni ions in the reaction solution is controlled to be (0.55-0.8):(0.1-0.25), for example, it can be 0.55:0.1, 0.58:0.12, 0.61:0.14, 0.64:0.16, 0.67:0.18, 0.70:0.20, 0.73:0.22, 0.76:0.24 or 0.80:0.25, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0055] In the present invention, in the coprecipitation reaction, the molar ratio of Mn ions to M ions in the reaction solution is controlled to be (0.55-0.8):(0.01-0.1), for example, it can be 0.55:0.01, 0.58:0.02, 0.61:0.03, 0.64:0.04, 0.67:0.05, 0.70:0.06, 0.73:0.07, 0.76:0.08, 0.79:0.09 or 0.80:0.10, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] In the present invention, in the coprecipitation reaction, the molar ratio of Mn ions to N ions in the reaction solution is controlled to be (0.55-0.8):(0.01-0.34), for example, it can be 0.55:0.01, 0.57:0.05, 0.59:0.09, 0.61:0.13, 0.63:0.17, 0.65:0.21, 0.67:0.25, 0.69:0.29, 0.71:0.33 or 0.80:0.34, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0057] Preferably, the coprecipitation reaction is also accompanied by stirring at a speed of 120 to 40 r / min, for example, it can be 120 r / min, 140 r / min, 160 r / min, 180 r / min, 200 r / min, 220 r / min, 240 r / min, 260 r / min, 280 r / min, 300 r / min, 320 r / min, 340 r / min, 360 r / min, 380 r / min or 400 r / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0058] Preferably, the coprecipitation reaction time is 30 to 180 h, for example, it can be 30 h, 40 h, 50 h, 60 h, 70 h, 80 h, 90 h, 100 h, 110 h, 120 h, 130 h, 140 h, 150 h, 160 h, 170 h or 180 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0059] In the present invention, the coprecipitation reaction can be carried out in a protective atmosphere or in a mixed atmosphere containing a protective gas and oxygen.

[0060] Preferably, the D50 particle size of the precipitate obtained in step (1) is 5 to 14 μm, for example, it can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm or 14 μm, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0061] Preferably, the mixing method in step (2) includes ultrasonic treatment.

[0062] Preferably, the ultrasonic treatment time is 10 to 60 min, for example, it can be 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0063] Preferably, step (2) further includes drying and screening performed sequentially between the mixing and the heat treatment.

[0064] In the present invention, since the mixed slurry will become compacted after drying, it is necessary to perform screening.

[0065] Preferably, a sieve of 100 to 300 mesh is used for screening between the mixing and the heat treatment, for example, 100 mesh, 120 mesh, 140 mesh, 160 mesh, 180 mesh, 200 mesh, 220 mesh, 240 mesh, 260 mesh, 280 mesh or 300 mesh, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0066] Preferably, the fluoride salt in the fluoride salt solution in step (2) comprises any one of ammonium fluoride, sodium fluoride, ammonium bifluoride, ammonium tetrafluoroborate or lithium fluoride, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of ammonium fluoride and sodium fluoride, a combination of ammonium bifluoride and ammonium tetrafluoroborate, a combination of lithium fluoride and ammonium fluoride, or a combination of ammonium fluoride, sodium fluoride and ammonium bifluoride.

[0067] Preferably, the concentration of the fluoride salt in the fluoride salt solution in step (2) is 1 to 10 mol / L, for example, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L or 10 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0068] Preferably, the heat treatment in step (2) is performed at a temperature of 700 to 900° C. and for a time of 4 to 18 hours.

[0069] In the present invention, the temperature of the heat treatment in step (2) is 700-900°C, for example, it can be 700°C, 725°C, 750°C, 775°C, 800°C, 825°C, 850°C, 875°C or 900°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0070] In the present invention, the heat treatment time in step (2) is 4 to 18 hours, for example, it can be 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours or 18 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0071] Preferably, the atmosphere of the heat treatment in step (2) includes any one of an inert gas atmosphere, a nitrogen atmosphere or an oxygen-containing atmosphere.

[0072] The oxygen-containing atmosphere in the present invention includes air atmosphere.

[0073] Preferably, the heat treatment in step (2) further includes aging, filtering, washing, drying, iron removal and screening in sequence.

[0074] In the present invention, the iron removal method is a method in the prior art, and all iron removal methods in the prior art can be applied. For example, it can be: using a disc-type iron remover to remove iron from the ternary precursor material, which is a process based on the principle of strong magnetic field adsorption to achieve efficient removal of iron impurities. The disc-type iron remover generates a strong magnetic field through an electromagnetic or permanent magnet. When the ternary precursor material (including slurry or powder) flows under the iron remover, the ferromagnetic impurities therein (such as elemental iron, iron oxides, etc.) will be adsorbed on the surface of the iron removal disk by the magnetic field, and the non-magnetic material will pass smoothly, thereby realizing the separation of iron impurities and the main material.

[0075] In the present invention, since compaction may occur after washing and drying, screening is required.

[0076] Preferably, after the heat treatment, after washing and drying, a sieve of 100 to 300 mesh is used for screening, for example, it can be 100 mesh, 120 mesh, 140 mesh, 160 mesh, 180 mesh, 200 mesh, 220 mesh, 240 mesh, 260 mesh, 280 mesh or 300 mesh, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0077] Preferably, the aging temperature is 50-80° C., and the aging time is 3-18 hours.

[0078] In the present invention, the aging temperature is 50-80°C, for example, it can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0079] In the present invention, the aging time is 3 to 18 hours, for example, it can be 3 hours, 5 hours, 7 hours, 9 hours, 11 hours, 13 hours, 15 hours, 17 hours or 18 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0080] Preferably, the washing comprises alkali washing and water washing performed sequentially.

[0081] Preferably, the alkali washing is performed 1 to 5 times, for example, 1 time, 2 times, 3 times, 4 times or 5 times.

[0082] Preferably, the temperature of the water used for washing is 40-85°C, for example, it can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C or 85°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0083] Preferably, the drying temperature is 120-190° C., and the drying time is 6-24 hours.

[0084] In the present invention, the drying temperature is 120-190°C, for example, it can be 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C or 190°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0085] In the present invention, the drying time is 6 to 24 hours, for example, it can be 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours or 24 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0086] As a preferred technical solution of the preparation method of the present invention, the preparation method comprises:

[0087] (1) firstly, adding a manganese salt, a nickel salt, an M salt, an N salt, a precipitant and a complexing agent into a solvent respectively to obtain a manganese salt solution, a nickel salt solution, an M salt solution, an N salt solution, a precipitant solution and a complexing agent solution; then, the obtained manganese salt solution, the nickel salt solution, the M salt solution, the N salt solution, the precipitant solution and the complexing agent solution are added in parallel to a reaction base solution having a pH of 11 to 11.5 and a complexing agent concentration of 2 to 8 g / L to form a reaction solution, controlling the temperature of the reaction solution to 45 to 70° C., the pH to 9 to 12, the complexing agent concentration to 2 to 12 g / L, and the molar ratio of Mn ion, Ni ion, M ion and N ion to be (0.55 to 0.8):(0.1 to 0.25):(0.01 to 0.1):(0.01 to 0.34), stirring at a speed of 120 to 400 r / min, and performing a coprecipitation reaction in the reaction solution to obtain a precipitate having a D50 particle size of 5 to 14 μm;

[0088] (2) mixing a fluoride salt solution with a concentration of 1 to 10 mol / L with the precipitate obtained in step (1) by ultrasonic treatment for 10 to 60 minutes to obtain a mixed slurry, drying the obtained mixed slurry and sieving it, and then heat-treating it at 700 to 900° C. for 4 to 18 hours; then aging the heat-treated material at 50 to 80° C. for 3 to 18 hours, first performing alkali washing 1 to 5 times, then washing it with water at 40 to 85° C., and then drying it at 120 to 190° C. for 6 to 24 hours to obtain a nickel-manganese-based precursor.

[0089] In a third aspect, the present invention provides a positive electrode material, which is prepared from a raw material including the nickel-manganese-based precursor described in the first aspect.

[0090] In a fourth aspect, the present invention provides a process for preparing the positive electrode material according to the third aspect, the process comprising:

[0091] The lithium source is mixed with the nickel-manganese-based precursor described in the first aspect, and then solid-phase sintering is performed to obtain the positive electrode material.

[0092] Preferably, the lithium source includes at least one of lithium hydroxide, lithium acetate, lithium chloride, lithium sulfate or lithium nitrate. Typical but non-limiting combinations include a combination of lithium hydroxide and lithium acetate, a combination of lithium chloride and lithium sulfate, a combination of lithium acetate and lithium nitrate, or a combination of lithium hydroxide, lithium chloride and lithium sulfate.

[0093] Preferably, in the mixture, the molar ratio between the lithium element in the lithium source and the transition metal element in the nickel-manganese-based precursor is (1-1.5):1, for example, it can be 1:1, 1.05:1, 1.10:1, 1.15:1, 1.20:1, 1.25:1, 1.30:1, 1.35:1, 1.40:1, 1.45:1 or 1.50:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0094] Preferably, the solid phase sintering includes a first heating, a first heat preservation, a second heating and a second heat preservation performed in sequence.

[0095] Preferably, the heating rate of the first heating is 2 to 10°C / min, for example, it can be 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min, but is not limited to the listed values. Other unlisted values ​​within this numerical range are also applicable. The end temperature of the first heating is the temperature of the first insulation.

[0096] Preferably, the temperature of the first insulation is 400-550° C., and the time is 2-12 hours.

[0097] In the present invention, the temperature of the first insulation is 400-550°C, for example, it can be 400°C, 425°C, 450°C, 475°C, 500°C, 525°C or 550°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0098] In the present invention, the first insulation time is 2 to 12 hours, for example, it can be 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours or 12 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0099] Preferably, the heating rate of the second heating is 2 to 10°C / min, for example, it can be 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min, and the endpoint temperature of the second heating is the temperature of the second insulation.

[0100] Preferably, the temperature of the second insulation is 750-1000° C., and the time is 12-36 hours.

[0101] In the present invention, the second insulation temperature is 750-1000°C, for example, it can be 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable.

[0102] In the present invention, the second insulation time is 12 to 36 hours, for example, it can be 12 hours, 15 hours, 18 hours, 21 hours, 24 hours, 27 hours, 30 hours, 33 hours or 36 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0103] Preferably, the solid-phase sintering atmosphere includes any one of an inert gas atmosphere, a nitrogen atmosphere or an oxygen-containing atmosphere.

[0104] The oxygen-containing atmosphere in the present invention includes air atmosphere.

[0105] In a fifth aspect, the present invention provides a battery comprising the positive electrode material described in the third aspect.

[0106] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0107] Compared with the prior art, the present invention has the following beneficial effects:

[0108] In the present invention, a nickel-manganese-based precursor is doped with three elements, namely, doping element F, doping element M and doping element N. After the positive electrode material is prepared using the nickel-manganese-based precursor, the Li ion site, transition metal ion site and oxygen full lattice site in the positive electrode material are partially and synergistically replaced by the three elements, namely, doping element F, doping element M and doping element N; wherein, the doping element F replaces O2- to form a strong F-transition metal bond, thereby inhibiting oxygen release; the doping element M and the doping element N achieve the widening of the Li interlayer spacing, thereby enhancing the diffusion rate of lithium ions, and shortening the Mn-O bond length, thereby stabilizing the transition metal layer; therefore, the positive electrode material prepared using the nickel-manganese-based precursor has good structural stability under high voltage, and the irreversible oxygen release agent and capacity attenuation are greatly improved; the lithium ion battery prepared using the obtained positive electrode material exhibits a higher discharge specific capacity and better cycle stability under high voltage conditions. DETAILED DESCRIPTION

[0109] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0110] Example 1

[0111] This embodiment provides a ternary co-doped nickel-manganese-based precursor, wherein the nickel-manganese-based precursor comprises element Mn, element Ni, doping element Mg and doping element Nb in a molar ratio of 0.75:0.20:0.03:0.02;

[0112] The nickel-manganese-based precursor further includes a doping element F, and the content of the doping element F in the nickel-manganese-based precursor gradually decreases from the surface to the center of the nickel-manganese-based precursor; the nickel-manganese-based precursor includes an oxygen element, and the molar ratio of the oxygen element to the doping element F is 9.5:0.5;

[0113] The D50 particle size of the nickel-manganese-based precursor is 10.2 μm;

[0114] The preparation method of the ternary co-doped nickel-manganese-based precursor is:

[0115] (1) first, manganese sulfate, nickel sulfate, magnesium sulfate, niobium oxalate, sodium hydroxide and polyvinyl pyrrolidone are added to deionized water respectively to obtain manganese sulfate solution, nickel sulfate solution, magnesium sulfate solution, niobium oxalate solution, sodium hydroxide solution and polyvinyl pyrrolidone solution; then, in a mixed atmosphere of nitrogen and oxygen with a volume ratio of 95:5, the obtained manganese sulfate solution, nickel sulfate solution, magnesium sulfate solution, niobium oxalate solution, sodium hydroxide solution and polyvinyl pyrrolidone solution are added in parallel to a reaction base liquid with a pH of 11.2 and a polyvinyl pyrrolidone concentration of 5 g / L to form a reaction solution, controlling the temperature of the reaction solution to 60° C., the pH to 11.2, the polyvinyl pyrrolidone concentration to 7 g / L, and the molar ratio of Mn ion, Ni ion, Mg ion and Nb ion to 0.75:0.20:0.03:0.02, while stirring at a speed of 350 r / min, and performing a coprecipitation reaction in the reaction solution to obtain a precipitate with a D50 particle size of 10 μm;

[0116] (2) Mixing a 5 mol / L ammonium fluoride solution and the precipitate obtained in step (1) by ultrasonic treatment for 130 min to obtain a mixed slurry, drying the obtained mixed slurry and then screening; then heat treating it at 800°C for 10 h in an argon atmosphere; then aging the heat-treated material at 65°C for 7 h, first performing alkali washing three times, then washing it with water at 60°C four times, and then drying it at 150°C for 16 h to obtain a nickel-manganese-based precursor.

[0117] This embodiment also provides a positive electrode material, and the preparation process of the positive electrode material is as follows:

[0118] Lithium hydroxide was mixed with the nickel-manganese-based precursor provided in this embodiment (in the mixture, the molar ratio between the lithium element in the lithium hydroxide and the transition metal element in the nickel-manganese-based precursor was 1.25:1), and then heated to 500° C. in an air atmosphere at a heating rate of 3° C. / min and kept warm for 6 h, and then heated to 900° C. at a heating rate of 5° C. / min and kept warm for 24 h to obtain a positive electrode material.

[0119] Example 2

[0120] This embodiment provides a ternary co-doped nickel-manganese-based precursor, wherein the nickel-manganese-based precursor comprises element Mn, element Ni, doping element Mg and doping element Nb in a molar ratio of 0.55:0.1:0.01:0.34;

[0121] The nickel-manganese-based precursor further includes a doping element F, and the content of the doping element F in the nickel-manganese-based precursor gradually decreases from the surface to the center of the nickel-manganese-based precursor; the nickel-manganese-based precursor includes an oxygen element, and the molar ratio of the oxygen element to the doping element F is 9:1;

[0122] The D50 particle size of the nickel-manganese-based precursor is 5.1 μm;

[0123] The preparation method of the ternary co-doped nickel-manganese-based precursor is:

[0124] (1) first, manganese nitrate, nickel nitrate, magnesium nitrate, niobium nitrate, sodium hydroxide and tartaric acid are added to deionized water respectively to obtain manganese nitrate solution, nickel nitrate solution, magnesium nitrate solution, niobium nitrate solution, sodium hydroxide solution and tartaric acid solution; then, in a nitrogen atmosphere, the obtained manganese nitrate solution, nickel nitrate solution, magnesium nitrate solution, niobium nitrate solution, sodium hydroxide solution and tartaric acid solution are added in parallel to a reaction base liquid having a pH of 11 and a tartaric acid concentration of 2 g / L to form a reaction solution, controlling the temperature of the reaction solution to 45° C., the pH to 9, the tartaric acid concentration to 2 g / L, and the molar ratio of Mn ion, Ni ion, Mg ion and Nb ion to 0.55:0.25:0.1:0.1, while stirring at a speed of 400 r / min, and performing a coprecipitation reaction in the reaction solution to obtain a precipitate with a D50 particle size of 5 μm;

[0125] (2) mixing a sodium fluoride solution having a concentration of 10 mol / L with the precipitate obtained in step (1) by ultrasonic treatment for 10 min to obtain a mixed slurry, drying the obtained mixed slurry and then sieving; then heat treating it at 900° C. for 4 h in a nitrogen atmosphere; then aging the heat-treated material at 50° C. for 18 h, first performing alkali washing 5 times, then washing it with water at 40° C., and then drying it at 190° C. for 6 h to obtain a nickel-manganese-based precursor.

[0126] This embodiment also provides a positive electrode material, and the preparation process of the positive electrode material is as follows:

[0127] Lithium hydroxide was mixed with the nickel-manganese-based precursor provided in this embodiment (in the mixture, the molar ratio between the lithium element in the lithium source and the transition metal element in the nickel-manganese-based precursor was 1.5:1), and then heated to 550°C in an air atmosphere at a heating rate of 10°C / min and kept warm for 2h, and then heated to 750°C at a heating rate of 2°C / min and kept warm for 36h to obtain a positive electrode material.

[0128] Example 3

[0129] This embodiment provides a ternary co-doped nickel-manganese-based precursor, wherein the nickel-manganese-based precursor comprises element Mn, element Ni, doping element Mg and doping element Nb in a molar ratio of 0.8:0.1:0.01:0.09;

[0130] The nickel-manganese-based precursor further includes a doping element F, and the content of the doping element F in the nickel-manganese-based precursor gradually decreases from the surface to the center of the nickel-manganese-based precursor; the nickel-manganese-based precursor includes an oxygen element, and the molar ratio of the oxygen element to the doping element F is 9.9:0.1;

[0131] The D50 particle size of the nickel-manganese-based precursor is 14 μm;

[0132] The preparation method of the ternary co-doped nickel-manganese-based precursor is:

[0133] (1) first, manganese sulfate, nickel sulfate, magnesium sulfate, niobium sulfate, tetramethylammonium hydroxide and ammonium bicarbonate are added to a solvent respectively to obtain a manganese sulfate solution, a nickel sulfate solution, a magnesium sulfate solution, a niobium sulfate solution, a tetramethylammonium hydroxide solution and an ammonium bicarbonate solution; then, in an argon atmosphere, the obtained manganese sulfate solution, nickel sulfate solution, magnesium sulfate solution, niobium sulfate solution, tetramethylammonium hydroxide solution and ammonium bicarbonate solution are added in parallel to a reaction base liquid having a pH of 11.5 and an ammonium bicarbonate concentration of 8 g / L to form a reaction solution, controlling the temperature of the reaction solution to 70° C., the pH to 12, the ammonium bicarbonate concentration to 12 g / L, and the molar ratio of Mn ions, Ni ions, Mg ions and Nb ions to 0.8:0.1:0.01:0.09, while stirring at a speed of 120 r / min, and performing a coprecipitation reaction in the reaction solution to obtain a precipitate having a D50 particle size of 13.8 μm;

[0134] (2) Mixing a 1 mol / L ammonium bifluoride solution and the precipitate obtained in step (1) by ultrasonic treatment for 60 min to obtain a mixed slurry, drying the obtained mixed slurry and then sieving; then heat treating it at 700°C for 18 h in an argon atmosphere; then aging the heat-treated material at 80°C for 3 h, first performing an alkali wash, then washing it with water at 85°C, and then drying it at 120°C for 24 h to obtain a nickel-manganese-based precursor.

[0135] This embodiment also provides a positive electrode material, and the preparation process of the positive electrode material is as follows:

[0136] Lithium hydroxide was mixed with the nickel-manganese-based precursor provided in this embodiment (in the mixture, the molar ratio between the lithium element in the lithium source and the transition metal element in the nickel-manganese-based precursor was 1:1), and then heated to 400°C in an air atmosphere at a heating rate of 2°C / min and kept warm for 12 hours, and then heated to 1000°C at a heating rate of 10°C / min and kept warm for 12 hours to obtain a positive electrode material.

[0137] Example 4

[0138] This embodiment provides a ternary co-doped nickel-manganese-based precursor, except that the doping element Mg in the nickel-manganese-based precursor is replaced with an equal molar amount of Al;

[0139] That is, in step (1) of the preparation method of the ternary co-doped nickel-manganese-based precursor, magnesium sulfate is replaced by an equal molar amount of aluminum nitrate, and the rest is the same as in Example 3.

[0140] This embodiment further provides a positive electrode material, which is the same as that in Example 3 except that the nickel-manganese-based precursor in the preparation process of the positive electrode material is the nickel-manganese-based precursor in this embodiment.

[0141] Example 5

[0142] This embodiment provides a ternary co-doped nickel-manganese-based precursor, except that the doping element Nb in the nickel-manganese-based precursor is replaced with an equal molar amount of Ti;

[0143] That is, in step (1) of the method for preparing the ternary co-doped nickel-manganese-based precursor, magnesium sulfate is replaced by titanium tetrachloride in an equal molar amount, and the rest is the same as in Example 3.

[0144] This embodiment further provides a positive electrode material, which is the same as that in Example 3 except that the nickel-manganese-based precursor in the preparation process of the positive electrode material is the nickel-manganese-based precursor in this embodiment.

[0145] Example 6

[0146] This embodiment provides a ternary co-doped nickel-manganese-based precursor, except that the molar ratio of element Mn, element Ni, doping element Mg and doping element Nb in the nickel-manganese-based precursor is 0.25:0.25:0.25:0.25;

[0147] That is, in step (1) of the method for preparing the ternary co-doped nickel-manganese-based precursor, the molar ratio of Mn ions, Ni ions, Mg ions and Nb ions in the reaction solution is controlled to be 0.25:0.25:0.25:0.25, and the rest is the same as Example 3.

[0148] This embodiment further provides a positive electrode material, which is the same as that in Example 3 except that the nickel-manganese-based precursor in the preparation process of the positive electrode material is the nickel-manganese-based precursor in this embodiment.

[0149] Example 7

[0150] This embodiment provides a ternary co-doped nickel-manganese-based precursor, except that the molar ratio of element Mn, element Ni, doping element Mg and doping element Nb in the nickel-manganese-based precursor is 0.64:0.08:0.21:0.07;

[0151] That is, in step (1) of the method for preparing the ternary co-doped nickel-manganese-based precursor, the molar ratio of Mn ions, Ni ions, Mg ions and Nb ions in the reaction solution is controlled to be 0.64:0.08:0.21:0.07, and the rest is the same as Example 3.

[0152] This embodiment further provides a positive electrode material, which is the same as that in Example 3 except that the nickel-manganese-based precursor in the preparation process of the positive electrode material is the nickel-manganese-based precursor in this embodiment.

[0153] Example 8

[0154] This embodiment provides a ternary co-doped nickel-manganese-based precursor, except that the molar ratio of element Mn, element Ni, doping element Mg and doping element Nb in the nickel-manganese-based precursor is 0.35:0.1:0.05:0.5;

[0155] That is, in step (1) of the method for preparing the ternary co-doped nickel-manganese-based precursor, the molar ratio of Mn ions, Ni ions, Mg ions and Nb ions in the reaction solution is controlled to be 0.35:0.1:0.05:0.5, and the rest is the same as Example 3.

[0156] This embodiment further provides a positive electrode material, which is the same as that in Example 3 except that the nickel-manganese-based precursor in the preparation process of the positive electrode material is the nickel-manganese-based precursor in this embodiment.

[0157] Example 9

[0158] This embodiment provides a ternary co-doped nickel-manganese-based precursor, except that the molar ratio of oxygen element to doping element F in the nickel-manganese-based precursor is 10:0.3;

[0159] That is, in step (2) of the method for preparing the ternary co-doped nickel-manganese-based precursor, except that the concentration of the ammonium bifluoride solution is 0.2 mol / L, the rest is the same as in Example 3.

[0160] This embodiment further provides a positive electrode material, which is the same as that in Example 3 except that the nickel-manganese-based precursor in the preparation process of the positive electrode material is the nickel-manganese-based precursor in this embodiment.

[0161] Example 10

[0162] This embodiment provides a ternary co-doped nickel-manganese-based precursor, except that the molar ratio of oxygen element to doping element F in the nickel-manganese-based precursor is 9:1.5;

[0163] That is, in step (2) of the method for preparing the ternary co-doped nickel-manganese-based precursor, except that the concentration of the ammonium bifluoride solution is 15 mol / L, the rest is the same as in Example 3.

[0164] This embodiment further provides a positive electrode material, which is the same as that in Example 3 except that the nickel-manganese-based precursor in the preparation process of the positive electrode material is the nickel-manganese-based precursor in this embodiment.

[0165] Example 11

[0166] This embodiment provides a ternary co-doped nickel-manganese-based precursor, except that the doping element F in the nickel-manganese-based precursor is only attached to the surface of the nickel-manganese-based precursor;

[0167] That is, except that step (2) of the preparation method of the ternary co-doped nickel-manganese-based precursor "further heat treatment at 700°C for 18 hours in an argon atmosphere; aging the heat-treated material at 80°C for 3 hours, first performing an alkali wash, then washing with water at 85°C, and then drying at 120°C for 24 hours" is omitted, the rest are the same as Example 1.

[0168] Comparative Example 1

[0169] This comparative example provides a ternary co-doped nickel-manganese-based precursor, except that the doping element Mg in the nickel-manganese-based precursor is omitted;

[0170] That is, except for omitting magnesium sulfate in step (1) of the preparation method of the ternary co-doped nickel-manganese-based precursor, the rest is the same as Example 3.

[0171] This comparative example also provides a positive electrode material, which is the same as Example 3 except that the nickel-manganese-based precursor in the preparation process of the positive electrode material is the nickel-manganese-based precursor in this comparative example.

[0172] Comparative Example 2

[0173] This comparative example provides a ternary co-doped nickel-manganese-based precursor, except that the doping element Nb in the nickel-manganese-based precursor is omitted;

[0174] That is, except for omitting niobium sulfate in step (1) of the method for preparing the ternary co-doped nickel-manganese-based precursor, the rest is the same as in Example 3.

[0175] This comparative example also provides a positive electrode material, which is the same as Example 3 except that the nickel-manganese-based precursor in the preparation process of the positive electrode material is the nickel-manganese-based precursor in this comparative example.

[0176] Comparative Example 3

[0177] This comparative example provides a ternary co-doped nickel-manganese-based precursor, except that the doping element F in the nickel-manganese-based precursor is omitted;

[0178] That is, except for omitting step (2) of the preparation method of the ternary co-doped nickel-manganese-based precursor, the rest is the same as Example 3.

[0179] This comparative example also provides a positive electrode material, which is the same as Example 3 except that the nickel-manganese-based precursor in the preparation process of the positive electrode material is the nickel-manganese-based precursor in this comparative example.

[0180] The positive electrode materials provided in the above embodiments and comparative examples, conductive carbon black and polyvinylidene fluoride were added to a double planetary mixer in a mass ratio of 92:4:4, and premixed at low speed (800 rpm) for 30 min before adding N-methylpyrrolidone (NMP) to control the liquid-solid ratio to 1:1.3, and then stirred at high speed (2500 rpm) for 4 h to form a uniform slurry; the slurry was coated on 12 μm aluminum foil using a doctor blade coater with a wet film thickness of 180 μm, first dried at 80 ° C for 2 h, and then transferred to a vacuum oven (≤-0.09 MPa) and dried at 120 ° C for 4 h until the NMP residue was <1000 ppm, and then cut to obtain the positive electrode sheet.

[0181] The obtained positive electrode sheet is then used to prepare a CR2032 button battery. The method for preparing the CR2032 button battery is as follows: using the obtained positive electrode sheet as the positive electrode, then using a metal lithium sheet as the negative electrode, using a Celgard2400 membrane as the membrane, and using a 1 mol / L LiPF6 solution as the electrolyte, and assembling to obtain a CR2032 button battery.

[0182] Then, electrochemical performance tests were carried out; the test voltage range was 2-4.8V, the current density was 1C, and the number of cycles was 200. The test obtained the 1C first discharge specific capacity of the button battery and the capacity retention rate after 200 cycles at 1C as shown in Table 1.

[0183] Table 1

[0184]

[0185]

[0186] From Table 1, we can get:

[0187] (1) The ternary co-doped nickel-manganese-based precursors provided in Examples 1 to 3 have good performance; therefore, after the positive electrode material is prepared using the nickel-manganese-based precursor, the battery containing the obtained positive electrode material exhibits a high discharge specific capacity and excellent cycle stability;

[0188] (2) By comparing Example 1 with Example 4, it can be seen that in the present invention, the type of the doping element M will affect the performance of the nickel-manganese-based precursor and the battery; when the doping element M is preferably elemental Mg, the battery shows better performance. This is because the ionic radius of magnesium and nickel are highly similar. When the doping element M is preferably elemental Mg, Mg can be uniformly doped at the nickel site without introducing significant lattice distortion or vacancies, which not only stabilizes the layered structure, but also reduces the lattice strain and microcracks during the charge and discharge process; in addition, the high strength of the Mg-O bond effectively inhibits oxygen precipitation and harmful phase changes during the cycle, slowing down structural degradation; therefore, the doping element M is preferably elemental Mg, which can improve the cycle stability of the battery; in addition, when the doping element M is preferably elemental Mg, magnesium remains inactive (+2 valence stable) during the electrochemical process, does not compete for the redox electrons of the active nickel, and ensures the high specific capacity of the battery;

[0189] (3) By comparing Example 1 with Example 4, it can be seen that in the present invention, the type of the doping element N will affect the performance of the nickel-manganese-based precursor and the battery; when the doping element N is preferably element Nb, the battery exhibits better performance, which is because the high valence state of Nb helps to form a strong Nb-O bond, effectively inhibiting oxygen precipitation and structural collapse at high voltage, and improving the cycle stability of the battery; in addition, Nb 5+ It remains inert within the electrochemical window, does not participate in redox and does not consume active lithium, thus ensuring the high specific capacity of the battery;

[0190] (4) By comparing Example 1 with Examples 6 to 8, it can be seen that in the present invention, the molar ratio of element Mn to doping element M, and the molar ratio of element Mn to doping element N in the nickel-manganese-based precursor will affect the performance of the nickel-manganese-based precursor and the battery; when the molar ratio of element Mn to doping element M is (0.55-0.8): (0.01-0.1), and the molar ratio of element Mn to doping element N is (0.55-0.8): (0.01-0.34), the battery exhibits better performance. This is because the doping element Mg stabilizes the lattice by matching the ionic radius and inhibits the structural phase transition, and the doping element Nb regulates the lattice parameters and promotes Li by virtue of its high valence state. + migration; when the molar ratio of element Mn to doping element Mg is (0.55-0.8): (0.01-0.1), the doping element Mg can effectively stabilize the structure without blocking the ion channel; when the molar ratio of element Mn to doping element Nb is (0.55-0.8): (0.01-0.34), Nb can optimize ion transport and avoid excessive introduction of lattice stress; in the present invention, by limiting the molar ratio of element Mn to doping element M and doping element N, the structural stability and ion conductivity of the nickel-manganese-based precursor and the positive electrode material are synergistically balanced, thereby improving battery performance;

[0191] (5) By comparing Example 1 with Examples 9 to 10, it can be seen that in the present invention, the molar ratio of oxygen element to doping element F in the nickel-manganese-based precursor affects the performance of the nickel-manganese-based precursor and the battery; when the molar ratio of oxygen element to doping element F is (9 to 10): (0.1 to 1), the battery exhibits better performance. This is because the doping element F can adjust the lattice parameters of the nickel-manganese-based precursor by replacing part of the lattice oxygen, shorten the Li+ migration path in the positive electrode material prepared from the nickel-manganese-based precursor, and enhance the electronic conductivity of the positive electrode material; appropriate amount of F doping can inhibit the decomposition and side reactions of the electrolyte, avoid lattice distortion caused by excessive F, and optimize the ion transfer kinetics through the electronegativity of F, synergistically improve the structural stability and interface stability of the material, thereby improving the performance of the battery prepared from the positive electrode material;

[0192] (6) By comparing Example 1 with Example 11, it can be seen that in the present invention, the precipitate after being immersed in the fluoride salt solution is heat-treated to promote the diffusion of fluorine into the interior of the nickel-manganese-based precursor, thereby forming a fluorination distribution of the nickel-manganese-based precursor with a high fluorine concentration on the surface and a low fluorine concentration in the bulk phase. The fluorine concentration gradually decreases from the surface to the core of the nickel-manganese-based precursor. The positive electrode material prepared with the nickel-manganese-based precursor is not easily corroded by the electrolyte, and can promote the formation of a dense CEI layer and reduce the ion transmission resistance, thereby helping to improve the performance of the nickel-manganese-based precursor and the battery;

[0193] (7) By comparing Example 1 with Comparative Examples 1 to 3, it can be seen that in the present invention, the nickel-manganese-based precursor is doped with three elements, namely, doping element F, doping element M and doping element N. After the positive electrode material is prepared using the nickel-manganese-based precursor, the Li ion site, transition metal ion site and oxygen full lattice site in the positive electrode material are partially and cooperatively replaced by the three elements, namely, doping element F, doping element M and doping element N; wherein, the doping element F replaces O2- to form a strong F-transition metal bond, which inhibits oxygen release; the doping element M and the doping element N realize the widening of the Li interlayer spacing, thereby enhancing the diffusion rate of lithium ions, and shortening the Mn-O bond length, thereby stabilizing the transition metal layer; therefore, the positive electrode material prepared using the nickel-manganese-based precursor has good structural stability under high voltage, and the irreversible oxygen release agent and capacity attenuation are greatly improved; the lithium ion battery prepared using the obtained positive electrode material exhibits a higher discharge specific capacity and better cycle stability under high voltage conditions.

[0194] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A ternary co-doped nickel-manganese-based precursor, characterized in that: The nickel-manganese-based precursor contains a doping element F and also contains different doping elements M and N. The doping element M and the doping element N independently include any one of Mg, Mo, Nb, Ga, B, Pb, W, Nb, Ti, Ce, V, Al, La, Zr or Bi.

2. The nickel-manganese-based precursor according to claim 1, characterized in that The content of the doping element F in the nickel-manganese-based precursor gradually decreases from the surface to the center of the nickel-manganese-based precursor; Preferably, the nickel-manganese-based precursor includes oxygen element, and the molar ratio of the oxygen element to the doping element F is (9-10):(0.1-1).

3. The nickel-manganese-based precursor according to claim 1, characterized in that The molar ratio between element Mn and element Ni in the nickel-manganese-based precursor is (0.55-0.8):(0.1-0.25); Preferably, the doping element M is element Mg; Preferably, in the nickel-manganese-based precursor, the molar ratio of element Mn to doping element M is (0.55-0.8):(0.01-0.1); Preferably, the doping element N is element Nb; Preferably, in the nickel-manganese-based precursor, the molar ratio of element Mn to doping element N is (0.55-0.8):(0.01-0.34); Preferably, the D50 particle size of the nickel-manganese-based precursor is 5 to 14 μm.

4. A method for preparing the nickel-manganese-based precursor according to any one of claims 1 to 3, characterized in that: The preparation method comprises: (1) using manganese salt, nickel salt, M salt, N salt, precipitant, complexing agent and solvent as raw materials, and preparing a precipitate by wet coprecipitation; (2) mixing a fluoride salt solution with the precipitate obtained in step (1), and then performing heat treatment to obtain the nickel-manganese-based precursor.

5. The preparation method according to claim 4, characterized in that The wet coprecipitation in step (1) comprises: firstly adding a manganese salt, a nickel salt, an M salt, an N salt, a precipitant and a complexing agent into a solvent respectively to obtain a manganese salt solution, a nickel salt solution, an M salt solution, an N salt solution, a precipitant solution and a complexing agent solution; then adding the obtained manganese salt solution, nickel salt solution, M salt solution, N salt solution, precipitant solution and complexing agent solution into a reaction base solution in parallel to form a reaction solution, and performing a coprecipitation reaction in the reaction solution to obtain a precipitate; Preferably, in the coprecipitation reaction, the temperature of the reaction solution is controlled to be 45-70° C., the pH is 9-12, and the concentration of the complexing agent is 2-12 g / L; Preferably, in the coprecipitation reaction, the molar ratio of Mn ions, Ni ions, M ions and N ions in the reaction solution is controlled to be (0.55-0.8):(0.1-0.25):(0.01-0.1):(0.01-0.34); Preferably, the D50 particle size of the precipitate obtained in step (1) is 5 to 14 μm; Preferably, the fluoride salt in the fluoride salt solution in step (2) comprises any one of ammonium fluoride, sodium fluoride, ammonium bifluoride, ammonium tetrafluoroborate or lithium fluoride, or a combination of at least two thereof; Preferably, the concentration of the fluoride salt in the fluoride salt solution in step (2) is 1 to 10 mol / L; Preferably, the heat treatment in step (2) is performed at a temperature of 700 to 900° C. and for a time of 4 to 18 hours.

6. The preparation method according to claim 4, characterized in that The preparation method comprises: (1) firstly, adding a manganese salt, a nickel salt, an M salt, an N salt, a precipitant and a complexing agent into a solvent respectively to obtain a manganese salt solution, a nickel salt solution, an M salt solution, an N salt solution, a precipitant solution and a complexing agent solution; then, the obtained manganese salt solution, the nickel salt solution, the M salt solution, the N salt solution, the precipitant solution and the complexing agent solution are added in parallel to a reaction base solution having a pH of 11 to 11.5 and a complexing agent concentration of 2 to 8 g / L to form a reaction solution, controlling the temperature of the reaction solution to 45 to 70° C., the pH to 9 to 12, the complexing agent concentration to 2 to 12 g / L, and the molar ratio of Mn ion, Ni ion, M ion and N ion to be (0.55 to 0.8):(0.1 to 0.25):(0.01 to 0.1):(0.01 to 0.34), stirring at a speed of 120 to 400 r / min, and performing a coprecipitation reaction in the reaction solution to obtain a precipitate having a D50 particle size of 5 to 14 μm; (2) mixing a fluoride salt solution with a concentration of 1 to 10 mol / L with the precipitate obtained in step (1) by ultrasonic treatment for 10 to 60 minutes to obtain a mixed slurry, drying the obtained mixed slurry and then sieving it, and then heat treating it at 700 to 900° C. for 4 to 18 hours; then aging the heat-treated material at 50 to 80° C. for 3 to 18 hours, first performing alkali washing 1 to 5 times, then washing it with water at 40 to 85° C., and then drying it at 120 to 190° C. for 6 to 24 hours to obtain a nickel-manganese-based precursor.

7. A positive electrode material, characterized in that The positive electrode material is prepared from raw materials including the nickel-manganese-based precursor according to any one of claims 1 to 3.

8. A process for preparing the positive electrode material according to claim 7, characterized in that: The preparation process comprises: The lithium source is mixed with the nickel-manganese-based precursor according to any one of claims 1 to 3, and then solid-phase sintering is performed to obtain a positive electrode material.

9. The preparation process according to claim 8, characterized in that: In the mixture, the molar ratio between the lithium element in the lithium source and the transition metal element in the nickel-manganese-based precursor is (1-1.5):1; Preferably, the solid phase sintering includes a first heating, a first heat preservation, a second heating and a second heat preservation performed in sequence; Preferably, the first heating rate is 2 to 10°C / min; Preferably, the temperature of the first insulation is 400-550°C and the time is 2-12 hours; Preferably, the second heating rate is 2 to 10°C / min; Preferably, the temperature of the second insulation is 750-1000° C., and the time is 12-36 hours.

10. A battery, characterized in that: The battery comprises the positive electrode material according to claim 7.

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