Positive electrode precursor material with full-concentration gradient distribution and preparation method and application of positive electrode precursor material

Abstract

The invention relates to a full-concentration gradient distribution positive electrode precursor material and a preparation method and application thereof, and the preparation method comprises the following steps: (1) carrying out first mixing on a first nickel source, a first cobalt source and a first manganese source to obtain a solution A; performing second mixing on a second nickel source, a second cobalt source and a second manganese source to obtain a solution B; (2) enabling the solution A, a complexing agent and a precipitator to flow into a base solution in parallel, and carrying out a first reaction; (3) pumping the solution B into the solution A at a flow rate L1, carrying out a second reaction on the solution A, a complexing agent and a precipitator at a flow rate L2, and then respectively adjusting the pumping flow rate of the solution B and the parallel flow rate of the solution A to L3, L4 and L3gt; l1, L2gt; and L4, carrying out a third reaction to obtain the positive electrode precursor material. According to the preparation method, gradient change of elements is realized, the growth speed of the precursor is increased, and the electrochemical performance of the positive electrode precursor material is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and in particular to a positive electrode precursor material with a full concentration gradient distribution, a preparation method thereof, and an application thereof. Background Art

[0002] Lithium-ion batteries are one of the most popular energy storage devices today. Their cathode materials are a key component that determines their energy density, cycle life, and safety. With the growing demand for high-energy-density, low-cost batteries in new energy vehicles and energy storage power stations, cathode material systems, such as ternary materials (NCM / NCA), lithium iron phosphate (LFP), and lithium cobalt oxide (LCO), have become a research hotspot.

[0003] Among them, ternary high-nickel positive electrode materials have the characteristics of high specific capacity and energy density, low cost and good adaptability to voltage platforms. As positive electrode materials for lithium-ion batteries, they have certain advantages, but they still have technical bottlenecks that need to be solved urgently, such as poor structural stability, easy phase change, microcracks and ion mixing, thermal safety risks, release of oxygen during thermal runaway, and even explosion, serious interfacial side reactions, leading to battery expansion and increased impedance. The above defects all affect the performance and operation of lithium-ion batteries.

[0004] At present, the existing technology mainly optimizes and modifies the defects of high-nickel ternary materials through element doping, structural design and preparation process. For example, the existing technology CN107579236A discloses a preparation method of a full-gradient high-nickel ternary precursor and a full-gradient high-nickel ternary positive electrode material, which comprises the following steps: preparing a mixed solution A, a mixed solution B and a mixed solution C, and pumping the mixed solution A, an alkaline solution and a chelating agent into the reactor in parallel. After the reaction time T1, the mixed solution B is continuously pumped into the mixed solution A at a rate V1, and after the reaction time T2, the mixed solution C is continuously pumped into the mixed solution B at a rate V2; the continuous variation of the feed and composition of nickel salt, cobalt salt and manganese salt is realized to obtain a full-gradient high-nickel ternary precursor. This method requires the preparation of three different nickel-cobalt-manganese ratios of high nickel, medium nickel and low nickel. Three storage tanks need to be set up in the process. The operation is relatively complicated and the cost is high. For mass production, the control process is complicated, and the performance of the obtained precursor material needs to be improved.

[0005] Therefore, how to shorten the preparation process of cathode precursor materials, reduce energy consumption, and improve the performance of cathode precursor materials has become an urgent problem to be solved. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a cathode precursor material with a full concentration gradient distribution, a preparation method thereof, and an application. The preparation method of the cathode precursor material with a full concentration gradient distribution provided by the present invention, by configuring two mixed metal salt solutions with different ratios, combining a specific solution pumping process, a co-current process, and regulating the flow rate of the solution, ensures the gradient change of elements and realizes accelerating the growth rate of the precursor, shortening the preparation time, reducing the energy consumption, and at the same time, the internal structure of the prepared precursor presents a divergent structure, which is beneficial to improving the electrochemical performance of the cathode material.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides a preparation method of a cathode precursor material with a full concentration gradient distribution, and the preparation method includes the following steps:

[0009] (1) Perform a first mixing of a first nickel source, a first cobalt source, and a first manganese source to obtain solution A; perform a second mixing of a second nickel source, a second cobalt source, and a second manganese source to obtain solution B; the molar concentration of nickel element in solution A > the molar concentration of nickel element in solution B;

[0010] (2) Co-currently flow solution A, a complexing agent, and a precipitating agent into a bottom solution for a first reaction to obtain seed particles;

[0011] (3) After the first reaction ends, pump solution B into solution A at a flow rate L1, and co-currently flow the solution A into which solution B is pumped, together with a complexing agent and a precipitating agent, into the product obtained from the first reaction at a flow rate L2, where L1 < L2, for a second reaction. Then, adjust the flow rate of solution B pumped into solution A and the co-current flow rate of the solution A into which solution B is pumped to L3 and L4 respectively, where L3 > L1 and L2 > L4, for a third reaction to obtain the cathode precursor material with a full concentration gradient distribution.

[0012] In the present invention, the "solution A into which solution B is pumped" refers to the mixed solution of solution A and solution B formed after solution B is pumped into solution A.

[0013] In the present invention, the "co-current flow rate of the solution A into which solution B is pumped" refers to the flow rate during the co-current process of the mixed solution of solution A and solution B after solution B is pumped into solution A, together with a precipitating agent and a complexing agent.

[0014] The present invention provides a method for preparing a positive electrode precursor material with a full concentration gradient distribution. Two mixed metal salt solutions with different proportions are configured, and a high-nickel content solution A is used to react in parallel to form seed particles of nickel, cobalt and manganese in specific proportions. Then, the ratio of Ni, Co and Mn in the feed is controlled by the flow rate of a low-nickel content solution B and solution A. At the same time, the flow rate L1 of solution B pumped into solution A and the feed flow rate L2 of solution A + solution B flowing to the reactor are controlled to react. Then, the flow rate of solution B pumped into solution A and the feed flow rate of solution A + solution B flowing to the reactor are further increased to continue the reaction. This not only ensures the gradient change of the elements, but also accelerates the growth rate of the precursor, thereby shortening the preparation time and reducing energy consumption. At the same time, a precursor material with an internal structure presenting an emitting structure is prepared, which is beneficial to improving the electrochemical performance of the positive electrode material prepared from the precursor material.

[0015] Preferably, the total concentration of metal ions in the solution A in step (1) is 1-4 mol / L, for example, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3.0 mol / L, 3.5 mol / L or 4.0 mol / L.

[0016] Preferably, in step (1), the molar ratio of the nickel element in the first nickel source, the cobalt element in the first cobalt source and the manganese element in the first manganese source is x1:y1:(1-x1-y1), wherein 0.5≤x1≤0.99, for example, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95 or 0.99, etc., and 0.01≤y1≤0.3, for example, 0.01, 0.05, 0.10, 0.15, 0.20, 0.25 or 0.30, etc.

[0017] Preferably, the total concentration of metal ions in the solution B in step (1) is 1-4 mol / L, for example, 1 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3.0 mol / L, 3.5 mol / L or 4 mol / L.

[0018] Preferably, in step (1), the molar ratio of the nickel element in the second nickel source, the cobalt element in the second cobalt source and the manganese element in the second manganese source is x2:y2:(1-x2-y2), wherein 0.1≤x2≤0.7, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 or 0.7, and 0.01≤y2≤0.5, for example, 0.01, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45 or 0.50, etc.

[0019] Preferably, the volume ratio of the solution A to the solution B is (1.8-2.2):1, for example, 1.8:1, 1.9:1, 2.0:1, 2.1:1 or 2.2:1, etc.

[0020] Preferably, the first nickel source and the second nickel source independently include any one of nickel sulfate, nickel chloride or nickel nitrate.

[0021] Preferably, the first cobalt source and the second cobalt source independently include any one of cobalt sulfate, cobalt chloride or cobalt nitrate.

[0022] Preferably, the first manganese source and the second manganese source independently include any one of manganese sulfate, manganese chloride or manganese nitrate.

[0023] Preferably, the concentration of the complexing agent in step (2) is 1-3 mol / L, such as 1 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L or 3.0 mol / L.

[0024] Preferably, the complexing agent in step (2) comprises any one of ammonia water, oxalic acid, ammonium chloride or ammonium bicarbonate, or a combination of at least two of them.

[0025] Preferably, the concentration of hydroxide ions in the precipitant in step (2) is 1-3 mol / L, such as 1 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L or 3.0 mol / L.

[0026] Preferably, the precipitant in step (2) comprises sodium hydroxide and / or potassium hydroxide.

[0027] Preferably, the base liquid in step (2) comprises a complexing agent, a precipitant and a solvent.

[0028] Preferably, the pH of the base solution in step (2) is 11-12.5, for example, 11.0, 11.2, 11.4, 11.6, 11.8, 12.0, 12.2, 12.4 or 12.5.

[0029] Preferably, the concentration of the complexing agent in the base solution in step (2) is 3-10 g / L, for example, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L or 10 g / L.

[0030] Preferably, the flow rate of the parallel flow of the solution A of the first reaction in step (2) is 20-40 L / h, for example, 20 L / h, 22 L / h, 24 L / h, 26 L / h, 28 L / h, 30 L / h, 32 L / h, 34 L / h, 36 L / h, 38 L / h or 40 L / h, etc.

[0031] Preferably, the pH of the first reaction system in step (2) is 11-12.5, for example, 11, 11.2, 11.4, 11.6, 11.8, 12.0, 12.2, 12.4 or 12.5.

[0032] Preferably, the total concentration of the complexing agent in the first reaction system in step (2) is 3-10 g / L, for example, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L or 10 g / L.

[0033] Preferably, the stirring speed in the first reaction system in step (2) is 400-450 r / min, for example, 400 r / min, 410 r / min, 420 r / min, 430 r / min, 440 r / min or 450 r / min.

[0034] Preferably, the first reaction in step (2) is carried out in an air atmosphere.

[0035] Preferably, the particle size D50 of the seed particles obtained in step (2) is 2-5 μm, for example, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm or 5.0 μm.

[0036] Preferably, in step (3), the ratio of the flow rate L1 to the flow rate L2 is (0.4-0.6):1, for example, 0.40:1, 0.42:1, 0.44:1, 0.46:1, 0.48:1, 0.50:1, 0.52:1, 0.54:1, 0.56:1, 0.58:1 or 0.60:1, etc.

[0037] Preferably, the flow rate L2 in step (3) is 20-40 L / h, for example, 20 L / h, 22 L / h, 24 L / h, 26 L / h, 28 L / h, 30 L / h, 32 L / h, 34 L / h, 36 L / h, 38 L / h or 40 L / h, etc.

[0038] Preferably, in step (3), an inert gas is introduced into the second reaction system.

[0039] Preferably, the inert gas flow rate is 1-3m 3 / h, for example 1.0m 3 / h、1.2m 3 / h、1.4m 3 / h、1.6m 3 / h、1.8m 3 / h, 2.0m 3 / h、2.2m 3 / h、2.4m 3 / h、2.6m3 / h、2.8m 3 / h or 3.0m 3 / h, etc.

[0040] Preferably, the concentration of the complexing agent in step (3) is 1-3 mol / L, such as 1 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L or 3.0 mol / L.

[0041] Preferably, the complexing agent in step (3) comprises any one of ammonia water, oxalic acid, ammonium chloride or ammonium bicarbonate, or a combination of at least two of them.

[0042] In the present invention, the complexing agents added in parallel in step (2) and step (3) can have the same composition or different compositions, or the same concentration or different concentrations, and those skilled in the art can make the selection as needed.

[0043] Preferably, the precipitant in step (3) comprises sodium hydroxide and / or potassium hydroxide.

[0044] Preferably, the concentration of hydroxide ions in the precipitant in step (3) is 1-3 mol / L, such as 1 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L or 3.0 mol / L.

[0045] In the present invention, the precipitants added in parallel in step (2) and step (3) can have the same composition or different compositions, or the same concentration or different concentrations, and those skilled in the art can make the selection as needed.

[0046] Preferably, the pH of the second reaction system in step (3) is 10-11.5, for example, 10, 10.2, 10.4, 10.6, 10.8, 11.0, 11.2, 11.4 or 11.5.

[0047] Preferably, the total concentration of the complexing agent in the system of the second reaction in step (3) is 4-12 g / L, for example, 4.5 g / L, 5.0 g / L, 5.5 g / L, 6.0 g / L, 6.5 g / L, 7.0 g / L, 7.5 g / L, 8.0 g / L, 8.5 g / L, 9.0 g / L, 9.5 g / L, 10.0 g / L, 10.5 g / L, 11.0 g / L, 11.5 g / L or 12.0 g / L, etc.

[0048] Preferably, the stirring speed in the system of the second reaction in step (3) is 200-400r / min, for example, 200r / min, 220r / min, 240r / min, 260r / min, 280r / min, 300r / min, 320r / min, 340r / min, 360r / min, 380r / min or 400r / min, etc.

[0049] Preferably, the temperature in the system of the second reaction in step (3) is 40-70°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C.

[0050] Preferably, the particle size D50 of the product obtained after the second reaction in step (3) is 5-10 μm, for example, 5 μm, 5.5 μm, 6.0 μm, 6.5 μm, 7.0 μm, 7.5 μm, 8.0 μm, 8.5 μm, 9.0 μm, 9.5 μm or 10.0 μm, etc.

[0051] Preferably, in step (3), the ratio of the flow rate L3 to the flow rate L1 is (1.2-2):1, such as 1.2:1, 1.4:1, 1.6:1, 1.8:1 or 2.0:1.

[0052] Preferably, in step (3), the ratio of the flow rate L4 to the flow rate L2 is (1.2-2):1, for example, 1.2:1, 1.4:1, 1.6:1, 1.8:1 or 2.0:1, etc.

[0053] Preferably, the ratio of the flow rate L3 to the flow rate L4 in step (3) is (0.4-0.6):1, for example, 0.40:1, 0.42:1, 0.44:1, 0.46:1, 0.48:1, 0.50:1, 0.52:1, 0.54:1, 0.56:1, 0.58:1 or 0.60:1, etc.

[0054] Preferably, the pH of the system of the third reaction in step (3) is 9-10.5, for example, 9, 9.2, 9.4, 9.6, 9.8, 10.0, 10.2, 10.4 or 10.5.

[0055] Preferably, the total concentration of the complexing agent in the third reaction system of step (3) is 3-9 g / L, for example, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L or 9 g / L.

[0056] Preferably, the stirring speed in the system of the third reaction in step (3) is 100-200 r / min, for example, 100 r / min, 120 r / min, 140 r / min, 160 r / min, 180 r / min or 200 r / min.

[0057] Preferably, the temperature in the system of the third reaction in step (3) is 40-70°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C.

[0058] Preferably, in step (3), an inert gas is introduced into the system of the third reaction.

[0059] Preferably, in the third reaction system, the inert gas flow rate is 3-5m 3 / h, for example 3.0m 3 / h、3.2m 3 / h、3.4m 3 / h、3.6m 3 / h、3.8m 3 / h、4.0m 3 / h、4.2m 3 / h、4.4m 3 / h、4.6m 3 / h、4.8m 3 / h or 5.0m 3 / h, etc.

[0060] Preferably, a fourth reaction is performed after the third reaction in step (3).

[0061] Preferably, during the fourth reaction, the flow rate of the solution B pumped into the solution A is L5, and the flow rate of the parallel flow of the solution A pumped into the solution B is L6, L5>L3, L6>L4.

[0062] Preferably, the ratio of the flow rate L5 to the flow rate L3 is (1.2-2):1, for example, 1.2:1, 1.4:1, 1.6:1, 1.8:1 or 2.0:1.

[0063] Preferably, the ratio of the flow rate L6 to the flow rate L4 is (1.2-2):1, for example, 1.2:1, 1.4:1, 1.6:1, 1.8:1 or 2.0:1, etc.

[0064] Preferably, the ratio of the flow rate L5 to the flow rate L6 is (0.4-0.6):1, for example, 0.40:1, 0.42:1, 0.44:1, 0.46:1, 0.48:1, 0.50:1, 0.52:1, 0.54:1, 0.56:1, 0.58:1 or 0.60:1, etc.

[0065] Preferably, the pH of the fourth reaction system is 9-10.5, for example, 9, 9.2, 9.4, 9.6, 9.8, 10.0, 10.2, 10.4 or 10.5.

[0066] Preferably, the total concentration of the complexing agent in the fourth reaction system is 3-9 g / L, for example, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L or 9 g / L.

[0067] Preferably, the stirring speed in the fourth reaction system is 100-200 r / min, for example, 100 r / min, 120 r / min, 140 r / min, 160 r / min, 180 r / min or 200 r / min.

[0068] Preferably, the temperature in the system of the fourth reaction is 40-70°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C.

[0069] Preferably, an inert gas is introduced into the system of the fourth reaction.

[0070] Preferably, in the fourth reaction system, the inert gas flow rate is 3-5m 3 / h, for example 3.0m 3 / h、3.2m 3 / h、3.4m 3 / h、3.6m 3 / h、3.8m 3 / h、4.0m 3 / h、4.2m 3 / h、4.4m 3 / h、4.6m 3 / h、4.8m 3 / h or 4.0m 3 / h, etc.

[0071] Preferably, the fourth reaction is followed by a fifth reaction.

[0072] Preferably, during the fifth reaction, the flow rate of the solution B pumped into the solution A is L7, and the flow rate of the parallel flow of the solution A pumped into the solution B is L8, L7>L5, L8>L6.

[0073] Preferably, the ratio of the flow rate L7 to the flow rate L5 is (1.2-2):1, for example, 1.2:1, 1.4:1, 1.6:1, 1.8:1 or 2.0:1, etc.

[0074] Preferably, the ratio of the flow rate L8 to the flow rate L6 is (1.2-2):1, for example, 1.2:1, 1.4:1, 1.6:1, 1.8:1 or 2.0:1, etc.

[0075] Preferably, the ratio of the flow rate L7 to the flow rate L8 is (0.4-0.6):1, for example, 0.40:1, 0.42:1, 0.44:1, 0.46:1, 0.48:1, 0.50:1, 0.52:1, 0.54:1, 0.56:1, 0.58:1 or 0.60:1, etc.

[0076] In the present invention, the flow rate in the fifth reaction process is further increased, wherein the co-current precipitant and complexing agent are increased synchronously, and the remaining parameter settings of the reaction system can be selected to be within the range of the various parameter settings in the fourth reaction process, and the remaining reaction parameters can be selected to be the same as or different from the setting parameters of the fourth reaction.

[0077] As needed, the preparation method provided by the present invention can further increase the pumping flow rate of solution B and the parallel flow rate of solution A pumped into solution B according to the specific increase multiple of the previous process, and perform subsequent sixth reactions, seventh reactions, etc. in sequence until the reaction is completed.

[0078] In a second aspect, the present invention provides a positive electrode precursor material with a full concentration gradient distribution, wherein the positive electrode precursor material with a full concentration gradient distribution is prepared using the preparation method described in the first aspect.

[0079] The positive electrode precursor material with full concentration gradient distribution provided by the present invention is prepared by a specific preparation method. The elements inside the positive electrode precursor material present a gradient distribution and a divergent structure, which is beneficial to improving the electrochemical performance of the positive electrode material.

[0080] Preferably, the structure of the positive electrode precursor material with full concentration gradient distribution is a hollow structure.

[0081] In the present invention, air is introduced into the system during the seed crystal phase to 2+ and Co 2+ Oxidation is performed to refine the primary particles of the seed crystal and to loosen the stacking, thereby obtaining an internal hollow structure.

[0082] Preferably, the positive electrode precursor material with full concentration gradient distribution is radiated from the inside to the outside.

[0083] Preferably, the nickel content of the positive electrode precursor material with full concentration gradient distribution gradually decreases from the inside to the outside, while the contents of cobalt and manganese gradually increase.

[0084] Preferably, the particle size D50 of the positive electrode precursor material with full concentration gradient distribution is 6-20 μm, for example, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm or 20 μm.

[0085] Preferably, the chemical formula of the positive electrode precursor material with full concentration gradient distribution is Ni x Co y Mn 1-x-y (OH)2, wherein x is 0.6-0.98, such as 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95 or 0.98, and y is 0.01-0.3, such as 0.01, 0.05, 0.10, 0.15, 0.20, 0.25 or 0.30, etc.

[0086] In a third aspect, the present invention provides a positive electrode material, which is prepared using the positive electrode precursor material with full concentration gradient distribution according to the second aspect.

[0087] The positive electrode material provided by the present invention is prepared from a positive electrode precursor material with a full concentration gradient distribution, which inherits the divergent structure of the precursor material. During the charge and discharge cycle, Li + It can be quickly deintercalated and arranged consistently during the cycle, with excellent rate performance and cycle performance, and the gradient element distribution ensures the high capacity and high safety performance of the material.

[0088] In a fourth aspect, the present invention provides a method for preparing the positive electrode material according to the third aspect, the preparation method comprising the following steps:

[0089] The positive electrode precursor material with full concentration gradient distribution according to the second aspect is mixed with a lithium source and sintered to obtain the positive electrode material.

[0090] Preferably, the lithium source comprises lithium hydroxide.

[0091] Preferably, the ratio of the total molar amount of metal ions in the positive electrode precursor material to the molar amount of lithium element in the lithium source is 1:(1.2-1.6), for example, 1:1.2, 1:1.3, 1:1.4, 1:1.5 or 1:1.6.

[0092] Preferably, the sintering temperature is 500-1000°C, for example, 500°C, 600°C, 700°C, 800°C, 900°C or 1000°C.

[0093] Preferably, the sintering time is 6-20 h, for example, 6 h, 8 h, 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, etc.

[0094] Preferably, the sintering is performed in an air atmosphere.

[0095] In a fifth aspect, the present invention provides a lithium-ion battery, comprising the positive electrode material according to the fourth aspect.

[0096] Compared with the prior art, the present invention has at least the following beneficial effects:

[0097] (1) The method for preparing a positive electrode precursor material with a full concentration gradient distribution provided by the present invention ensures the gradient change of elements and accelerates the growth rate of the precursor by configuring two mixed metal salt solutions in different proportions, combining a specific solution pumping process, a parallel flow process and regulating the solution flow rate, shortening the preparation time and reducing energy consumption. At the same time, the internal structure of the prepared precursor presents a divergent structure, which is beneficial to improving the electrochemical performance of the positive electrode material.

[0098] (2) The positive electrode material provided by the present invention is prepared from a positive electrode precursor material with a full concentration gradient distribution, and still has a divergent structure of the precursor material. During the charge and discharge cycle, Li + It can be quickly deintercalated and arranged consistently during the cycle, with excellent rate performance and cycle performance, and the gradient element distribution ensures the high capacity and high safety performance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] Figure 1 It is a schematic diagram of the device structure used in the method for preparing the positive electrode precursor material provided by the present invention.

[0100] Among them, 1, the first container tank; 2, the second container tank; 3, the reactor; 4, the third container tank; 5, the fourth container tank.

[0101] Figure 2 This is a scanning electron microscope image of the positive electrode precursor material obtained by the preparation method provided in Example 1. DETAILED DESCRIPTION

[0102] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0103] The following examples provide a schematic diagram of the device structure used in the preparation method. Figure 1 As shown by Figure 1It can be seen that the discharge port of the first container tank 1 containing solution B is connected to the feed port of the second container tank 2 containing solution A, the discharge port of the second container tank 2 is connected to one feed port of the reactor 3, and the discharge ports of the third container tank 4 containing the precipitant and the fourth container tank 5 containing the complexing agent are connected to the feed port of the reactor 3.

[0104] Example 1

[0105] This embodiment provides a method for preparing a positive electrode precursor material with a full concentration gradient distribution, which specifically includes the following steps:

[0106] S1. Nickel sulfate, cobalt sulfate, manganese sulfate were first mixed with deionized water in a molar ratio of nickel, cobalt and manganese of 0.98:0.01:0.01 to prepare solution A, wherein the total concentration of metal ions in solution A was 2 mol / L and the volume was 20 m 3 .

[0107] Nickel sulfate, cobalt sulfate, manganese sulfate and deionized water were first mixed in a molar ratio of nickel, cobalt and manganese of 0.70:0.15:0.15 to prepare solution B. The total concentration of metal ions in solution B was 2 mol / L and the volume was 10m 3 .

[0108] S2. Solution A, 2 mol / L ammonia water and 2 mol / L sodium hydroxide were flowed into a reactor containing a bottom liquid to carry out a first coprecipitation reaction, wherein the bottom liquid included ammonia water, sodium hydroxide and deionized water, the concentration of ammonia water in the bottom liquid was 4 g / L, the pH of the bottom liquid was 11.2-11.8, the flow rate of the co-flow of solution A during the first coprecipitation reaction was 30 L / h, the pH in the system of the first coprecipitation reaction was maintained at 11.6, the ammonia water concentration was maintained at 5 g / L, the stirring speed was 400 r / min, and the first coprecipitation reaction was carried out in an air atmosphere to obtain seed particles with a particle size D50 of 3 μm.

[0109] S3. After the first coprecipitation reaction, solution B was pumped into solution A at a flow rate of 15 L / h, and solution A pumped into solution B was added to the reactor at a flow rate of 30 L / h with a 2 mol / L ammonia solution and a 2 mol / L sodium hydroxide solution, and a second coprecipitation reaction was performed. The pH of the second coprecipitation reaction system was maintained at 11, the ammonia concentration was maintained at 5 g / L, the stirring speed of the system was 300 r / min, and the temperature was 50 ° C. During the second coprecipitation reaction, inert gas argon was introduced into the reaction system, and the argon inlet flow rate was 2m 3 / h, to obtain a product of the second coprecipitation reaction with a particle size D50 of 5 μm.

[0110] S4. The flow rate of solution B pumped into solution A was 25 L / h, and the flow rate of solution A pumped into solution B to the reactor was 50 L / h. The solution was continued to flow into the reactor with a concentration of 2 mol / L ammonia solution and a concentration of 2 mol / L sodium hydroxide solution to carry out a third coprecipitation reaction. The pH of the system of the third coprecipitation reaction was maintained at 10, the total concentration of ammonia in the system was maintained at 8 g / L, the stirring speed of the system was 150 r / min, the temperature was 60 ° C, and during the third coprecipitation reaction, inert gas argon was introduced into the reaction system, and the flow rate of argon was 3m 3 / h, and a positive electrode precursor material with a particle size D50 of 11 μm was obtained, and the chemical formula was Ni 0.88 Co 0.06 Mn 0.06 (OH)2, the structure is hollow inside and divergent from the inside to the outside, and the element distribution is that the Ni element gradually decreases from the inside to the outside, while the Co element and Mn element gradually increase.

[0111] Example 2

[0112] This embodiment provides a method for preparing a positive electrode precursor material with a full concentration gradient distribution, comprising the following steps:

[0113] S1. Nickel chloride, cobalt chloride, and manganese chloride were first mixed with deionized water in a molar ratio of nickel, cobalt, and manganese of 0.8:0.1:0.1 to prepare a solution A, wherein the total concentration of metal ions in the solution A was 1 mol / L and the volume was 20 m 3 .

[0114] Nickel chloride, cobalt chloride, and manganese chloride were first mixed with deionized water in a molar ratio of nickel, cobalt, and manganese of 0.4:0.3:0.3 to prepare a solution B. The total concentration of metal ions in the solution B was 1 mol / L, and the volume was 10 m 3 .

[0115] S2. Solution A, 1 mol / L ammonia water and 1 mol / L sodium hydroxide were flowed into a reactor containing a bottom liquid to carry out a first coprecipitation reaction, wherein the bottom liquid included ammonia water, sodium hydroxide and deionized water, the concentration of ammonia water in the bottom liquid was 5 g / L, and the pH of the bottom liquid was 11.0-11.5. The flow rate of the co-flow of solution A during the first coprecipitation reaction was 20 L / h, the pH in the system of the second coprecipitation reaction was maintained at 11, the ammonia water concentration was maintained at 6 g / L, the stirring speed was 450 r / min, and the first coprecipitation reaction was carried out in an air atmosphere to obtain seed particles with a particle size D50 of 2 μm.

[0116] S3. After the first coprecipitation reaction, solution B was pumped into solution A at a flow rate of 8 L / h, and solution A pumped into solution B was added to the reactor at a flow rate of 20 L / h with a 1 mol / L ammonia solution and a 1 mol / L sodium hydroxide solution, and a second coprecipitation reaction was performed. The pH of the second coprecipitation reaction system was maintained at 10.5, the ammonia concentration was maintained at 6 g / L, the stirring speed of the system was 200 r / min, and the temperature was 40 ° C. During the second coprecipitation reaction, inert gas argon was introduced into the reaction system, and the argon inlet flow rate was 1m 3 / h, to obtain a product of the second coprecipitation reaction with a particle size D50 of 5 μm.

[0117] S4. The flow rate of solution B pumped into solution A was increased to 12 L / h, and the flow rate of solution A pumped into solution B to the reactor was 30 L / h. The solution was then added to the reactor in parallel with an aqueous ammonia solution having a concentration of 1 mol / L and a sodium hydroxide solution having a concentration of 1 mol / L to carry out a third coprecipitation reaction. The pH of the system during the third coprecipitation reaction was maintained at 9, the total concentration of ammonia in the system was 5 g / L, the stirring speed of the system was 100 r / min, and the temperature was 40°C. During the third coprecipitation reaction, inert argon gas was introduced into the reaction system, and the flow rate of argon gas was 4 m 3 / h, and obtain the positive electrode precursor material with a particle size D50 of 10μm, the chemical formula is Ni 0.67 Co 0.17 Mn 0.16 (OH)2, the structure is hollow inside and divergent from the inside to the outside, and the element distribution is that the Ni element gradually decreases from the inside to the outside, while the Co element and Mn element gradually increase.

[0118] Example 3

[0119] This embodiment provides a method for preparing a positive electrode precursor material with a full concentration gradient distribution, comprising the following steps:

[0120] S1. Nickel nitrate, cobalt nitrate, and manganese nitrate were first mixed with deionized water in a molar ratio of nickel, cobalt, and manganese of 0.9:0.05:0.05 to prepare a solution A having a total metal ion concentration of 4 mol / L and a volume of 30 m 3 .

[0121] Nickel nitrate, cobalt nitrate, manganese nitrate and deionized water were first mixed in a molar ratio of nickel, cobalt and manganese of 0.34:0.33:0.33 to prepare solution B. The total concentration of metal lithium ions in solution B was 4 mol / L and the volume was 15m 3 .

[0122] S2. Solution A, 3 mol / L ammonia water and 3 mol / L sodium hydroxide were flowed into a reactor containing a bottom liquid to carry out a first coprecipitation reaction, wherein the bottom liquid included ammonia water, sodium hydroxide and deionized water, the concentration of ammonia water in the bottom liquid was 8 g / L, and the pH of the bottom liquid was 11.5-12. The flow rate of the co-flow of solution A during the first coprecipitation reaction was 20 L / h, and the pH in the system of the second coprecipitation reaction was maintained at 12.5, the ammonia water concentration was maintained at 10 g / L, the stirring speed was 450 r / min, and the first coprecipitation reaction was carried out in an air atmosphere to obtain seed particles with a particle size D50 of 5 μm.

[0123] S3. After the first coprecipitation reaction, solution B was pumped into solution A at a flow rate of 12 L / h, and solution A pumped into solution B was added to the reactor at a flow rate of 20 L / h with a 3 mol / L ammonia solution and a 3 mol / L sodium hydroxide solution, and a second coprecipitation reaction was performed. The pH of the second coprecipitation reaction system was maintained at 11, the ammonia concentration was maintained at 8 g / L, the stirring speed of the system was 380 r / min, and the temperature was 70 ° C. During the second coprecipitation reaction, inert gas argon was introduced into the reaction system, and the argon inlet flow rate was 3m 3 / h, to obtain a product of the second coprecipitation reaction with a particle size D50 of 10 μm.

[0124] S4. The flow rate of solution B pumped into solution A was 24 L / h, and the flow rate of solution A pumped into solution B to the reactor was 40 L / h. The solution was continued to flow into the reactor with a concentration of 3 mol / L ammonia solution and a concentration of 3 mol / L sodium hydroxide solution to carry out a third coprecipitation reaction. The pH of the system of the third coprecipitation reaction was maintained at 10.5, the total concentration of ammonia in the system was maintained at 9 g / L, the stirring speed of the system was 200 r / min, the temperature was 70 ° C, and during the third coprecipitation reaction, inert gas argon was introduced into the reaction system, and the flow rate of argon was 5m 3 / h, and a third coprecipitation reaction with a particle size D50 of 15 μm was obtained.

[0125] S5. The flow rate of solution B pumped into solution A was 36 L / h, the flow rate of solution A pumped into solution B to the reactor was 60 L / h, and continued with a 3 mol / L ammonia solution and a 3 mol / L sodium hydroxide solution and flowed into the reactor to carry out the fourth coprecipitation reaction. The pH of the fourth coprecipitation reaction system was maintained at 10.5, the total concentration of ammonia in the system was maintained at 9 g / L, the stirring speed of the system was 200 r / min, the temperature was 70 ° C, and during the fourth coprecipitation reaction, inert gas argon was introduced into the reaction system, and the argon flow rate was 5m 3 / h, and obtain the positive electrode precursor material with a particle size D50 of 20 μm, the chemical formula is Ni 0.72 Co 0.14 Mn 0.14 (OH)2, the structure is hollow inside and divergent from the inside to the outside, and the element distribution is that the Ni element gradually decreases from the inside to the outside, while the Co element and Mn element gradually increase.

[0126] Example 4

[0127] The only difference between this embodiment and Example 1 is that the flow rate of the first coprecipitation reaction in step S2 is 15 L / h, the flow rate of solution B pumped into solution A in the second coprecipitation reaction in step S3 is 7.5 L / h, and the flow rate of solution A pumped into solution B and then flowing into the reactor is 15 L / h. All other contents are the same as in Example 1.

[0128] Example 5

[0129] The only difference between this embodiment and Example 1 is that the flow rate of the first coprecipitation reaction in step S2 is 45 L / h, the flow rate of solution B pumped into solution A in the second coprecipitation reaction in step S3 is 20 L / h, and the flow rate of solution A pumped into solution B and then flowing into the reactor is 45 L / h. All other contents are the same as in Example 1.

[0130] Example 6

[0131] The only difference between this embodiment and embodiment 1 is that the first coprecipitation reaction in step S2 is carried out in an argon atmosphere. The rest of the contents are the same as those in embodiment 1.

[0132] Example 7

[0133] The only difference between this embodiment and embodiment 1 is that the temperature of the second coprecipitation reaction in step S3 is 30° C., and the temperature of the third coprecipitation reaction in step S4 is 30° C. The rest of the contents are the same as those in embodiment 1.

[0134] Example 8

[0135] The only difference between this embodiment and embodiment 1 is that the temperature of the second coprecipitation reaction in step S3 is 80° C., and the temperature of the third coprecipitation reaction in step S4 is 80° C. The rest of the contents are the same as those in embodiment 1.

[0136] Comparative Example 1

[0137] The difference between this comparative example and Example 1 is only that: the flow rate of the parallel flow of solution A in the first coprecipitation reaction of step S2 is 50L / h, the flow rate at which solution B of the second coprecipitation reaction of step S3 is pumped into solution A is 25L / h, and the flow rate at which solution A is pumped into solution B and flows into the reactor is 50L / h, and the flow rate at which solution B is pumped into solution A in the third coprecipitation reaction of step S4 is also 25L / h, and the flow rate at which solution A is pumped into solution B and flows into the reactor is also 50L / h, that is, the flow rates of the second coprecipitation reaction and the third coprecipitation reaction are identical. The remaining contents are all the same as in Example 1.

[0138] Comparative Example 2

[0139] This comparative example differs from Example 1 only in that the pumping of solution B into solution A in steps S3 and S4 is omitted, and solution A, an aqueous ammonia solution, and a sodium hydroxide solution are simply fed into the reactor to prepare the cathode precursor material. The remainder of the process is the same as in Example 1.

[0140] Application Example 1

[0141] This application example provides a positive electrode material, which is prepared using the positive electrode precursor material provided in Example 1, and includes the following steps:

[0142] The positive electrode precursor material provided in Example 1 and lithium hydroxide are mixed evenly by a high-speed mixer according to a molar ratio of metal ions in the precursor material to lithium ions in lithium hydroxide of 1:1.2. Then, the mixture is sintered in a box furnace under an air atmosphere at a sintering temperature of 800°C and a sintering time of 10 hours. The mixture is cooled to 25°C to obtain a positive electrode material.

[0143] Application Example 2-8 and Comparative Application Example 1-2

[0144] The only difference between Application Examples 2-8 and Comparative Application Examples 1-2 and Application Example 1 is that the positive electrode precursor materials used are the positive electrode precursor materials provided in Examples 2-8 and Comparative Examples 1-2. The rest of the contents are the same as Application Example 1.

[0145] The positive electrode materials provided in Application Examples 1-8 and Comparative Application Examples 1-2 were assembled into lithium-ion batteries. The specific assembly process was as follows: the positive electrode materials provided in Application Examples 1-8 and Comparative Application Examples 1-2 were uniformly mixed with PVDF binder, conductive carbon black and N-methylpyrrolidone in a mass ratio of 8:1:1 to obtain a mixed slurry, and the mixed slurry was coated on a current collector to form a positive electrode sheet, which was then assembled into a lithium-ion battery together with a metal lithium negative electrode sheet, a separator, and an electrolyte containing 1 mol / L LiPF6 dissolved in EC and DMC solvent (volume ratio 3:7).

[0146] The capacity performance and cycle performance of the lithium-ion battery assembled above were tested in the voltage range of 2.5-4.3V, and the first cycle discharge capacity at 0.2C and the capacity retention rate after 100 cycles at 1C were recorded.

[0147] The test results are shown in Table 1.

[0148] Table 1

[0149]

[0150] The test results show that:

[0151] (1) It can be seen from Application Examples 1 to 3 that the method for preparing a positive electrode precursor material with a full concentration gradient distribution provided by the present invention ensures the gradient change of elements and accelerates the growth rate of the precursor by configuring two mixed metal salt solutions in different proportions, combining a specific solution pumping process, a parallel flow process and regulating the solution flow rate, shortening the preparation time and reducing energy consumption. At the same time, the internal structure of the prepared precursor presents a divergent structure, which is beneficial to improving the charge and discharge cycle performance and rate performance of the positive electrode material.

[0152] Figure 2 A scanning electron microscope image of the cathode precursor material obtained by the preparation method provided in Example 1 is given. As can be seen from the image, the cathode precursor material with full gradient distribution prepared in Example 1 is a hollow emitting structure.

[0153] (2) By comparing Application Example 1 with Application Examples 4-5, it can be seen that in the present invention, if the solutions of the first coprecipitation reaction and the second coprecipitation reaction flow in parallel and the flow rate of the pump is too low, the particle size growth rate will be too low, affecting the morphology of the primary particles of the precursor material; if the flow rate is too high, the particles of the precursor material will be severely agglomerated, the consistency will deteriorate, and the electrochemical performance will be affected.

[0154] (3) By comparing Application Example 1 and Application Example 6, it can be seen that if the reaction atmosphere of the first coprecipitation reaction is replaced with an argon atmosphere in the present invention, the interior of the particles will be relatively dense and a hollow structure cannot be formed, thereby affecting the capacity performance of the obtained positive electrode material.

[0155] (4) By comparing Application Example 1 with Application Examples 7-8, it can be seen that if the temperature of the second coprecipitation reaction and the third coprecipitation reaction is too low, the primary particles of the precursor will be too fine and the crystallinity will deteriorate, affecting the cycle performance of the positive electrode material prepared from the positive electrode precursor material; if the temperature of the second coprecipitation reaction and the third coprecipitation reaction is too high, the primary particles of the positive electrode precursor material will be too coarse and the crystallinity will be too high, and the activity of the precursor material will be reduced, which is not conducive to the sintering mixed with the lithium source in the subsequent preparation process of the positive electrode material, affecting the capacity performance of the positive electrode material.

[0156] (5) By comparing Application Example 1 with Comparative Application Example 1, it can be seen that if the first coprecipitation reaction, the second coprecipitation reaction, and the third coprecipitation reaction of the present invention use the same solution flow or pumping flow rate, the cycle performance of the positive electrode material prepared from the resulting precursor material will be significantly reduced.

[0157] (6) By comparing Application Example 1 with Comparative Application Example 2, it can be seen that if the pumping of solution B into solution A is omitted in the present invention, the cycle performance of the positive electrode material prepared from the obtained precursor material will be significantly reduced.

[0158] In summary, the preparation method of the positive electrode precursor material with a full concentration gradient distribution provided by the present invention is to configure two mixed metal salt solutions with different proportions, and use a high nickel content solution A to react in parallel to form a specific proportion of nickel, cobalt and manganese seed particles, and then control the feed Ni, Co and Mn ratio by the flow rate of the low nickel content solution B and the solution A, and at the same time control the flow rate of solution B pumped into solution A and the feed flow rate of solution A + solution B flowing to the reactor, and then further increase the flow rate of solution B pumped into solution A and the feed flow rate of solution A + solution B flowing to the reactor to continue the reaction, which not only ensures the gradient change of the elements, but also accelerates the growth rate of the precursor, thereby shortening the preparation time and reducing energy consumption. At the same time, a precursor material with an internal structure presenting an emitting structure is prepared, which is beneficial to improving the charge and discharge cycle performance and rate performance of the positive electrode material prepared from the precursor material.

[0159] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection 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 scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a positive electrode precursor material with a full concentration gradient distribution, characterized in that: The preparation method includes the following steps: (1) First, mix a first nickel source, a first cobalt source, and a first manganese source to obtain solution A; then mix a second nickel source, a second cobalt source, and a second manganese source to obtain solution B; the molar concentration of nickel element in solution A > the molar concentration of nickel element in solution B; (2) Co-currently introduce solution A, a complexing agent, and a precipitating agent into a bottom solution for a first reaction to obtain seed particles; (3) After the first reaction ends, pump solution B into solution A at a flow rate of L1, and co-currently introduce the solution A into which solution B is pumped, together with the complexing agent and the precipitating agent, into the product obtained from the first reaction at a flow rate of L2, where L1 < L2, for a second reaction. Then, adjust the flow rate of solution B pumped into solution A and the co-current flow rate of the solution A into which solution B is pumped to L3 and L4 respectively, where L3 > L1 and L2 > L4, for a third reaction to obtain the positive electrode precursor material with a full concentration gradient distribution.

2. The preparation method according to claim 1, characterized in that In step (1), the total concentration of metal ions in solution A is 1 - 4 mol / L; Preferably, the molar ratio of nickel element in the first nickel source, cobalt element in the first cobalt source, and manganese element in the first manganese source in step (1) is x1:y1:(1 - x1 - y1), where 0.5 ≤ x1 ≤ 0.99 and 0.01 ≤ y1 ≤ 0.3; Preferably, the total concentration of metal ions in solution B in step (1) is 1 - 4 mol / L; Preferably, the molar ratio of nickel element in the second nickel source, cobalt element in the second cobalt source, and manganese element in the second manganese source in step (1) is x2:y2:(1 - x2 - y2), where 0.1 ≤ x2 ≤ 0.7 and 0.01 ≤ y2 ≤ 0.5; Preferably, the volume ratio of solution A to solution B is (1.8 - 2.2):1; Preferably, the concentration of the complexing agent in step (2) is 1 - 3 mol / L; Preferably, the concentration of hydroxide ions in the precipitating agent in step (2) is 1 - 3 mol / L; Preferably, the co-current flow rate of solution A in the first reaction in step (2) is 20 - 40 L / h; Preferably, the pH of the system in the first reaction in step (2) is 11 - 12.5; Preferably, the total concentration of the complexing agent in the system of the first reaction in step (2) is 3 - 10 g / L; Preferably, the stirring speed in the system of the first reaction in step (2) is 400 - 450 r / min; Preferably, the first reaction in step (2) is carried out in an air atmosphere; Preferably, the particle size D50 of the seed particles obtained in step (2) is 2 - 5 μm.

3. The preparation method according to claim 1 or 2, characterized in that In step (3), the ratio of the flow rate L1 to the flow rate L2 is (0.4 - 0.6):1; Preferably, the flow rate L2 in step (3) is 20 - 40 L / h; Preferably, an inert gas is introduced into the system of the second reaction in step (3); Preferably, the inert gas flow rate is 1-3m 3 / h; Preferably, the pH of the system in the second reaction in step (3) is 10 - 11.5; Preferably, the total concentration of the complexing agent in the second reaction system in step (3) is 4-12 g / L; Preferably, the stirring speed in the second reaction system in step (3) is 200-400 r / min; Preferably, the temperature in the system of the second reaction in step (3) is 40-70°C; Preferably, the particle size D50 of the product obtained after the second reaction in step (3) is 5-10 μm.

4. The preparation method according to any one of claims 1 to 3, characterized in that In step (3), the ratio of the flow rate L3 to the flow rate L1 is (1.2-2):1; Preferably, in step (3), the ratio of the flow rate L4 to the flow rate L2 is (1.2-2):1; Preferably, the pH of the system of the third reaction in step (3) is 9-10.5; Preferably, the total concentration of the complexing agent in the third reaction system of step (3) is 3-9 g / L; Preferably, the stirring speed in the third reaction system of step (3) is 100-200 r / min; Preferably, the temperature in the system of the third reaction in step (3) is 40-70°C.

5. The preparation method according to any one of claims 1 to 4, characterized in that After the third reaction in step (3), a fourth reaction is further performed; Preferably, during the fourth reaction, the flow rate of the solution B pumped into the solution A is L5, and the flow rate of the parallel flow of the solution A pumped into the solution B is L6, L5>L3, L6>L4; Preferably, the ratio of the flow rate L5 to the flow rate L3 is (1.2-2):1; Preferably, the ratio of the flow rate L6 to the flow rate L4 is (1.2-2):1; Preferably, the fourth reaction is followed by a fifth reaction; Preferably, during the fifth reaction, the flow rate of the solution B pumped into the solution A is L7, and the flow rate of the parallel flow of the solution A pumped into the solution B is L8, L7>L5, L8>L6; Preferably, the ratio of the flow rate L7 to the flow rate L5 is (1.2-2):1; Preferably, the ratio of the flow rate L8 to the flow rate L6 is (1.2-2):

1.

6. A cathode precursor material with a full concentration gradient distribution, characterized in that: The positive electrode precursor material with full concentration gradient distribution is prepared by the preparation method according to any one of claims 1 to 5.

7. The positive electrode precursor material with full concentration gradient distribution according to claim 6, characterized in that: The structure of the positive electrode precursor material with full concentration gradient distribution is a hollow structure; Preferably, the nickel content of the positive electrode precursor material with full concentration gradient distribution gradually decreases from the inside to the outside, while the contents of cobalt and manganese gradually increase; Preferably, the particle size D50 of the positive electrode precursor material with full concentration gradient distribution is 6-20 μm; Preferably, the chemical formula of the positive electrode precursor material with full concentration gradient distribution is Ni x Co y Mn 1-x-y (OH)2, wherein x is 0.6-0.98 and y is 0.01-0.

3.

8. A positive electrode material, characterized in that The positive electrode material is prepared using the positive electrode precursor material with full concentration gradient distribution according to claim 6 or 7.

9. A method for preparing a positive electrode material according to claim 8, characterized in that: The preparation method comprises the following steps: The positive electrode precursor material with full concentration gradient distribution according to claim 6 or 7 is mixed with a lithium source and sintered to obtain the positive electrode material.

10. A lithium ion battery, characterized in that: The lithium-ion battery comprises the positive electrode material according to claim 8.

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