Cobalt-free nlmnal precursor of composite structure, preparation method thereof, positive electrode material, lithium ion battery and electric device

Abstract

The application provides a cobalt-free NiMnAl precursor with a composite structure, a preparation method of the cobalt-free NiMnAl precursor, a positive electrode material, a lithium ion battery and an electric device, and relates to the technical field of new energy sources.The cobalt-free NiMnAl precursor with the composite structure provided by the application is composed of a monoclinic beta-MOOH phase and a hexagonal alpha phase, the cobalt-free NiMnAl precursor with the composite structure is composed of secondary particles formed by closely stacking uniform flaky nanoparticles, the particle size distribution is uniform, the sphericity is good, and the specific gravity is high, and the cobalt-free NiMnAl precursor can be used for preparing a low-cost and high-performance lithium-rich manganese-based positive electrode material.

Description

Technical Field

[0001] The present application relates to the field of new energy technology, and in particular to a cobalt-free NiMnAl precursor with a composite structure and a preparation method thereof, a positive electrode material, a lithium-ion battery, and an electrical device. Background Art

[0002] Currently, there are no reports on the use of composite oxyhydroxides as raw materials for the preparation of manganese-based cathode materials. This is primarily due to the fact that the manganese in the layered manganese oxyhydroxides within the composite structure is +3 valent, sensitive to moisture and oxygen, highly reactive and unstable, and easily generates manganese tetraoxide, forming a mixed phase. This leads to uneven morphology and elemental distribution, resulting in reduced capacity and performance of the cathode material. Therefore, there is a clear need for a technical solution to address these issues. Summary of the Invention

[0003] The purpose of this application is to provide a composite cobalt-free NiMnAl precursor and its preparation method, positive electrode material, lithium-ion battery and electrical equipment, aiming to solve the problem in the prior art that the composite structure of oxyhydroxide is prone to produce manganese tetraoxide impurities, resulting in reduced capacity and performance of the positive electrode material.

[0004] To achieve the above objectives, the present application provides a cobalt-free NiMnAl precursor with a composite structure, characterized in that the cobalt-free NiMnAl precursor with a composite structure is composed of a monoclinic β-MOOH phase and a hexagonal α phase.

[0005] In some embodiments, the cobalt-free NiMnAl precursor of the composite structure includes secondary particles formed by stacking a plurality of flaky nano primary particles, wherein the secondary particles meet at least one of the following conditions:

[0006] A. The particle size D50 of the secondary particles is 3 to 5 μm;

[0007] B. The tap density of the secondary particles is 1.0 to 1.55 g / cm 3 .

[0008] In some embodiments, at least one of the following conditions is met:

[0009] A. The monoclinic β-MOOH phase satisfies: α=90°, β=108°~109°, γ=90°;

[0010] B. The hexagonal α phase satisfies: α=90°, β=90°, γ=120°;

[0011] C. The cobalt-free NiMnAl precursor of the composite structure has no tetragonal phase (Ni xMn 1-x )3O4;

[0012] D. Na of the cobalt-free NiMnAl precursor of the composite structure is less than 120 ppm;

[0013] E. The S content of the cobalt-free NiMnAl precursor of the composite structure is less than 1800 ppm.

[0014] In some embodiments, the chemical formula of the monoclinic β-MOOH phase of the cobalt-free NiMnAl precursor of the composite structure is Ni x-τ M τ Mn 1-x OOH, the chemical formula of the hexagonal α phase is (Ni x-τ M τ Mn 1-x ) 1-t Al t (OH)2(CO3) t / 2 The content of the hexagonal α phase is m, the content of the monoclinic β-MOOH phase is 1-m, and the total chemical formula of the cobalt-free NiMnAl precursor of the composite structure is m(Ni x-τ M τ Mn 1-x ) 1-t Al t (OH)2(CO3) t / 2 ·(1-m)Ni x-τ M τ Mn 1-x OOH, wherein M is one or more of Ca, Mg, Fe, Cu, Zn, and Cd, τ<0.01, 0.25<x<0.50, 0.005<mt<0.01, 0.035<m<0.06, and 1 / 6≤t≤1 / 4.

[0015] The present application also provides a method for preparing the above-mentioned cobalt-free NiMnAl precursor of the composite structure, comprising:

[0016] Passing a mixed metal salt solution, a precipitant, a complexing agent, and an oxidant into the bottom liquid of a reactor to perform a co-precipitation reaction to obtain a slurry, and separating the slurry to obtain a solid precipitate;

[0017] The solid precipitate and the aging solution are mixed to carry out aging reaction and washing to obtain an aged product;

[0018] The aged product is sequentially subjected to a first drying process to a moisture content of less than 5% and a second drying process to a moisture content of less than 1%, wherein the temperature of the first drying process is lower than the temperature of the second drying process, to obtain the cobalt-free NiMnAl precursor of the composite structure.

[0019] In some embodiments, at least one of the following conditions is met:

[0020] A. the molar concentration of the oxidant in the coprecipitation reaction system is less than 5% of the total metal ion concentration in the mixed metal salt solution;

[0021] B. the temperature of the coprecipitation reaction is 45 to 55° C.;

[0022] C. the pH of the coprecipitation reaction is 9.9 to 11.5;

[0023] D. the stirring speed of the coprecipitation reaction is 400-500 rpm;

[0024] E. The oxidant comprises one or more of sodium hypochlorite, sodium persulfate, hydrogen peroxide, compressed air or a nitrogen / air mixture;

[0025] F. The molar concentration of the complexing agent in the coprecipitation reaction system is less than 1% of the total metal ion concentration in the mixed metal salt solution;

[0026] G. The color of the slurry is quantitatively measured by a Lab colorimeter, with an L value of 40 to 50, an a value of 0 to 4, and a b value of 20 to 25;

[0027] H. The flow rate of the mixed metal salt solution is 80 to 360 mL / min.

[0028] In some embodiments, at least one of the following conditions is met:

[0029] A. The mixed metal salt solution is a soluble salt solution of nickel, manganese and aluminum metals, and the soluble salt includes one or more soluble sulfates, nitrates, acetates or chlorides;

[0030] B. the total metal ion concentration in the mixed metal salt solution is 0.5 to 4 mol / L;

[0031] C. the precipitant comprises one or more of sodium hydroxide, sodium carbonate, potassium hydroxide, and lithium hydroxide;

[0032] D. the concentration of the precipitant is 1 to 10 mol / L;

[0033] E. the complexing agent includes one or more of ammonia water, ammonium sulfate, ammonium carbonate, and ammonium bicarbonate;

[0034] F. The concentration of the complexing agent is 0.1 to 5 mol / L;

[0035] G. the aging solution comprises one or more of sodium hydroxide, sodium carbonate, and sodium bicarbonate;

[0036] H. the temperature of the first drying is not higher than 60°C;

[0037] I. The temperature of the second drying is not higher than 110°C.

[0038] The present application also provides a positive electrode material, which is prepared from the above-mentioned cobalt-free NiMnAl precursor with a composite structure.

[0039] The present application also provides a lithium-ion battery comprising the above-mentioned positive electrode material.

[0040] The present application also provides an electrical device comprising the above-mentioned lithium-ion battery.

[0041] Compared with the prior art, the advantages of this application include:

[0042] The cobalt-free NiMnAl precursor with a composite structure provided in the present application is composed of a monoclinic β-MOOH phase and a hexagonal α phase. The cobalt-free NiMnAl precursor with a composite structure does not produce a manganese tetraoxide heterophase, and thus secondary particles with uniform morphology and element distribution and densely packed flaky nanoparticles can be obtained. The particles have uniform particle size distribution, good sphericity, and high specific gravity, and can be used to prepare low-cost, high-performance lithium-rich manganese-based positive electrode materials.

[0043] The preparation method of the cobalt-free NiMnAl precursor of the composite structure provided in the present application is to add an oxidant during the coprecipitation reaction and perform low-temperature pre-drying and high-temperature drying on the coprecipitated product in sequence. The purpose is to stabilize the layered manganese oxyhydroxide without introducing the manganese tetraoxide impurity phase, and at the same time introduce a small amount of α phase through trivalent aluminum to form a microscopic composite structure, thereby preparing a cobalt-free NiMnAl precursor composed of a monoclinic β-MOOH phase and a hexagonal α phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0045] Figure 1 This is an SEM image of the cobalt-free NiMnAl precursor of the composite structure prepared in Example 2;

[0046] Figure 2 This is the XRD pattern of the cobalt-free NiMnAl precursor of the composite structure prepared in Example 2;

[0047] Figure 3 This is an SEM image of the cobalt-free NiMnAl precursor of the composite structure prepared in Example 5;

[0048] Figure 4 This is the XRD pattern of the cobalt-free NiMnAl precursor of the composite structure prepared in Example 5;

[0049] Figure 5 This is an SEM image of the cobalt-free nickel-manganese precursor prepared in Comparative Example 1;

[0050] Figure 6 XRD pattern of the cobalt-free nickel-manganese precursor prepared in Comparative Example 1

[0051] Figure 7 This is an SEM image of the cobalt-free nickel-manganese precursor prepared in Comparative Example 2;

[0052] Figure 8 This is the XRD pattern of the cobalt-free nickel-manganese precursor prepared in Comparative Example 2. DETAILED DESCRIPTION

[0053] As used herein:

[0054] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0055] The conjunction "consisting of" excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed, excluding materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim, rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0056] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0057] In these examples, parts and percentages are by mass unless otherwise indicated.

[0058] "Parts by mass" refers to the basic unit of measurement used to express the mass ratio of multiple components. One part can represent any unit of mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, this means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, we could say that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number representing a multiplication factor). It's important to note that, unlike parts by mass, the sum of the mass of all components is not limited to 100 parts.

[0059] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0060] The unit cell is the smallest repeating unit in a crystal structure. It is able to construct the entire crystal structure through its own repetition. The side lengths and angles between the sides of the unit cell are important parameters that describe the unit cell's geometric properties and are usually expressed as lattice constants. The lattice constants include the three side lengths (a, b, c) and the angles between the three sides (α, β, γ).

[0061] In crystallography, the side lengths and angles of the unit cell are crucial for determining the symmetry and space group of a crystal. For example, the unit cell parameters of the cubic crystal system are characterized by a = b = c, and α = β = γ = 90°. This means that all sides of the cubic unit cell are equal in length, and all angles between them are right angles.

[0062] For other crystal systems, the relationship between the side lengths and angles of the unit cell is different. For example, the unit cell parameters of the tetragonal system are a = b ≠ c, and α = β = γ = 90°; the unit cell parameters of the hexagonal system are a = b ≠ c, α = β = 90°, and γ = 120°; and the unit cell parameters of the triclinic system are a ≠ b ≠ c, and α ≠ β ≠ γ ≠ 90°.

[0063] The size and shape of the unit cell are determined by these lattice parameters, which are the basic descriptors of the crystal structure. In practical material science research, the lattice constant is the basic structural parameter of crystalline materials and is directly related to the binding energy between atoms. Changes in the lattice constant can reflect changes in the composition, stress state, etc. inside the crystal. Usually, the SI unit of the lattice constant is meter, but in practical applications, the lattice constant is usually in a few angstroms. of the order of magnitude, that is, a few tenths of a nanometer.

[0064] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, the conditions are carried out according to conventional conditions or manufacturer recommendations. The reagents or instruments used are not specified by the manufacturer and are conventional products that can be purchased commercially.

[0065] Example 1

[0066] This embodiment first provides a cobalt-free NiMnAl precursor, the preparation method of which includes the following steps:

[0067] ① Preparation of feed solution: Dissolve nickel sulfate, ferrous sulfate, manganese sulfate, and aluminum sulfate in deionized water at a stoichiometric molar ratio of Ni:Fe:Mn:Al = 0.2772:0.001:0.7128:0.009 to prepare a mixed metal ion solution with a total metal ion concentration of 2 mol / L. Add industrial-grade liquid caustic soda to water to prepare a 10 mol / L precipitant solution. Dissolve concentrated ammonia in water to prepare a 6 mol / L complexing agent solution.

[0068] ② Coprecipitation reaction: 80L of water and an appropriate amount of ammonia water and alkali solution were added to a 100L reactor, the ammonia concentration was adjusted to 0.015mol / L, the pH value was 11.00-11.20, the reaction temperature was 45°C, and the stirring speed was 500r / min; and the mixed metal ion salt solution, alkali solution and ammonia solution were pumped into the reactor for coprecipitation reaction, and a mixed gas of nitrogen and air was introduced at 90L / h, the nitrogen / oxygen ratio was 5, and the molar concentration of oxygen in the system was 2.3% of the total metal ion concentration in the mixed metal salt solution. The flow rate of the mixed metal salt solution was 240mL / min, and the alkali solution and ammonia solution were pumped in to adjust the pH value of the system to 10.30 and the ammonia concentration to 0.015mol / L, so as to stably control the particles to be maintained in the range of 3.0-5.0 microns. The residence time of the slurry in the reactor was controlled to be 14-15 hours. During the reaction, due to the oxidizing effect of the oxidant, part of the divalent manganese in the precipitation material was oxidized to trivalent manganese, and the color of the material was light brown. The Lab values ​​of an appropriate amount of slurry measured by a colorimeter were 48.6, 3.9, and 21.3, respectively. The precipitation reaction slurry was discharged into the aging tank through the overflow port.

[0069] ③ After the material flowing into the aging tank is separated, 100L of dilute alkali for aging is used for 100kg of material, and it is aged for 30 minutes in a 5% sodium hydroxide solution at 70℃ and washed until the supernatant of the slurry is neutral, and then separated and dewatered.

[0070] ④ The dehydrated material was pre-dried at 60°C to a moisture content of less than 5%, and then dried at 110°C to a moisture content of less than 1% to obtain the cobalt-free NiMnAl precursor of the composite structure of Example 1, the chemical formula of which is 0.05(Ni 0.28 Mn 0.72 ) 0.8 (Al 0.9 Fe 0.1 ) 0.2 (OH)2(CO3) 0.1 0.95Ni 0.28 Mn 0.72 OOH.

[0071] This embodiment also provides a positive electrode material, and the preparation method thereof is as follows: the precursor material obtained in step ④ and lithium hydroxide are mixed in a molar ratio of 1:1.12, and sintered at 950° C. in an oxygen atmosphere for 5 hours to obtain the positive electrode material.

[0072] This embodiment also provides a battery, in which the positive electrode material obtained in this embodiment is assembled into a button-type battery according to conventional methods in the art.

[0073] Example 2

[0074] This embodiment first provides a cobalt-free NiMnAl precursor, the preparation method of which includes the following steps:

[0075] ① Preparation of feed solution: Dissolve nickel sulfate, manganese sulfate, and aluminum sulfate in deionized water at a stoichiometric molar ratio of Ni:Mn:Al = 0.2775:0.7135:0.009 to prepare a mixed metal ion solution with a total metal ion concentration of 2 mol / L. Add industrial-grade liquid caustic soda to water to prepare a 10 mol / L precipitant solution. Dissolve concentrated ammonia in water to prepare a 6 mol / L complexing agent solution.

[0076] ② Coprecipitation reaction: 80L of water and an appropriate amount of ammonia water and alkali solution were added to a 100L reactor, the ammonia concentration was adjusted to 0.015mol / L, the pH value was 11.00-11.20, the reaction temperature was 45°C, and the stirring speed was 500r / min; and the mixed metal ion salt solution, alkali solution and ammonia solution were pumped into the reactor for coprecipitation reaction, and hydrogen peroxide was introduced at the same time. The molar concentration of hydrogen peroxide in the system was 3.8% of the total metal ion concentration in the mixed metal salt solution. The flow rate of the mixed metal salt solution was 240mL / min. The alkali solution and ammonia solution were pumped in to adjust the pH value of the system to 10.20 and the ammonia concentration to 0.015mol / L to stably control the particles to be maintained in the range of 3.0-5.0 microns. The residence time of the slurry in the reactor was controlled to be 14-15 hours. During the reaction, due to the oxidizing effect of the oxidant, part of the divalent manganese in the precipitation material was oxidized to trivalent manganese, and the color of the material was light brown. The Lab values ​​of an appropriate amount of slurry measured by a colorimeter were 45.2, 2.6, and 22.9, respectively. The precipitation reaction slurry was discharged into the aging tank through the overflow port.

[0077] ③ After the material flowing into the aging tank is separated, 100L of dilute alkali for aging is used for 100kg of material, and it is aged for 30 minutes in a 5% sodium hydroxide solution at 70℃ and washed until the supernatant of the slurry is neutral, and then separated and dewatered.

[0078] ④ The dehydrated material was pre-dried at 60°C to a moisture content of less than 5%, and then dried at 110°C to a moisture content of less than 1% to obtain the cobalt-free NiMnAl precursor of the composite structure of Example 2, the chemical formula of which is 0.045 (Ni 0.28 Mn 0.72 ) 0.8 Al 0.2 (OH)2(CO3) 0.1 0.955Ni 0.28 Mn 0.72 OOH, its SEM picture is as follows Figure 1 As shown in the figure, the morphology of the precursor is a secondary particle formed by the accumulation of multiple thin-sheet nano primary particles. The nanosheets are small and uniform, with small pores between the sheets. There are no irregular particles (impurities) on the surface of the secondary particles. The XRD pattern is shown in the figure. Figure 2 As shown, according to the XRD pattern, the precursor is composed of the main phase β-MOOH and the auxiliary phase α, among which 19°, 34°, and 38° correspond to the β-MOOH phase; 11° and 23° correspond to the α phase.

[0079] This embodiment also provides a positive electrode material, and the preparation method thereof is as follows: the precursor material obtained in step ④ and lithium hydroxide are mixed in a molar ratio of 1:1.12, and sintered at 950° C. in an oxygen atmosphere for 5 hours to obtain the positive electrode material.

[0080] This embodiment also provides a battery, in which the positive electrode material obtained in this embodiment is assembled into a button-type battery according to conventional methods in the art.

[0081] Example 3

[0082] This embodiment first provides a cobalt-free NiMnAl precursor, the preparation method of which includes the following steps:

[0083] ① Preparation of feed solution: Dissolve nickel sulfate, manganese sulfate, and aluminum sulfate in deionized water at a stoichiometric molar ratio of Ni:Mn:Al = 0.2775:0.7135:0.009 to prepare a mixed metal ion solution with a total metal ion concentration of 2 mol / L. Add industrial-grade liquid caustic soda to water to prepare a 10 mol / L precipitant solution. Dissolve concentrated ammonia in water to prepare a 6 mol / L complexing agent solution.

[0084] ② Coprecipitation reaction: 80L of water and an appropriate amount of ammonia and alkali solution were added to a 100L reactor, the ammonia concentration was adjusted to 0.015mol / L, the pH value was 11.00-11.20, the reaction temperature was 45°C, and the stirring speed was 500r / min; and the mixed metal ion salt solution, alkali solution and ammonia solution were pumped into the reactor for coprecipitation reaction, and an aqueous solution of sodium persulfate was introduced at the same time. The molar concentration of sodium persulfate in the system was 4.5% of the total metal ion concentration in the mixed metal salt solution. The flow rate of the mixed metal salt solution was 240mL / min. The alkali solution and ammonia solution were pumped in to adjust the pH value of the system to 10.10 and the ammonia concentration to 0.015mol / L to stably control the particles to be maintained in the range of 3.0-5.0 microns. The residence time of the slurry in the reactor was controlled to be 14-15 hours. During the reaction, due to the oxidizing effect of the oxidant, part of the divalent manganese in the precipitation material was oxidized to trivalent manganese, and the color of the material was light brown. The Lab values ​​of an appropriate amount of slurry measured by a colorimeter were 41.8, 0.6, and 24.4, respectively. The precipitation reaction slurry was discharged into the aging tank through the overflow port.

[0085] ③ After the material flowing into the aging tank is separated, 100L of dilute alkali for aging is used for 100kg of material, and it is aged for 30 minutes in a 5% sodium hydroxide solution at 70℃ and washed until the supernatant of the slurry is neutral, and then separated and dewatered.

[0086] ④ The dehydrated material was pre-dried at 60°C to a moisture content of less than 5%, and then dried at 110°C to a moisture content of less than 1% to obtain the cobalt-free NiMnAl precursor of the composite structure of Example 3, the chemical formula of which is 0.045 (Ni 0.28 Mn 0.72 ) 0.8 Al 0.2 (OH)2(CO3) 0.1 0.955Ni0.28 Mn 0.72 OOH.

[0087] This embodiment also provides a positive electrode material, and the preparation method thereof is as follows: the precursor material obtained in step ④ and lithium hydroxide are mixed in a molar ratio of 1:1.12, and sintered at 950° C. in an oxygen atmosphere for 5 hours to obtain the positive electrode material.

[0088] This embodiment also provides a battery, in which the positive electrode material obtained in this embodiment is assembled into a button-type battery according to conventional methods in the art.

[0089] Example 4

[0090] This embodiment first provides a cobalt-free NiMnAl precursor, the preparation method of which includes the following steps:

[0091] ① Preparation of feed solution: Dissolve nickel sulfate, manganese sulfate, and aluminum nitrate in deionized water at a stoichiometric molar ratio of Ni:Mn:Al = 0.331:0.661:0.008 to prepare a mixed metal ion solution with a total metal ion concentration of 2 mol / L. Add industrial-grade liquid caustic soda to water to prepare a 10 mol / L precipitant solution. Dissolve concentrated ammonia in water to prepare a 6 mol / L complexing agent solution.

[0092] ② Coprecipitation reaction: 80L of water and an appropriate amount of ammonia water and alkali solution were added to a 100L reactor, the ammonia concentration was adjusted to 0.018mol / L, the pH value was 11.00-11.20, the reaction temperature was 50°C, and the stirring speed was 450r / min; and the mixed metal ion salt solution, alkali solution and ammonia solution were pumped into the reactor for coprecipitation reaction, and a mixed gas of nitrogen and air was introduced at 60L / h, the nitrogen / oxygen ratio was 5, the molar concentration of oxygen in the system was 2.5% of the total metal ion concentration in the mixed metal salt solution, the flow rate of the mixed metal salt solution was 160mL / min, the alkali solution and ammonia solution were pumped in to adjust the pH value of the system to 10.35 and the ammonia concentration to 0.018mol / L to stably control the particles to be maintained in the range of 3.0-5.0 microns, and the residence time of the slurry in the reactor was controlled to be 14-15 hours. During the reaction, due to the oxidizing effect of the oxidant, part of the divalent manganese in the precipitation material was oxidized to trivalent manganese, and the color of the material was light brown. The Lab values ​​of an appropriate amount of slurry measured by a colorimeter were 47.2, 3.4, and 20.5, respectively. The precipitation reaction slurry was discharged into the aging tank through the overflow port.

[0093] ③ After the material flowing into the aging tank is separated, 100L of dilute alkali for aging is used for 100kg of material, and it is aged for 30 minutes in a 5% sodium hydroxide solution at 70℃ and washed until the supernatant of the slurry is neutral, and then separated and dewatered.

[0094] ④ The dehydrated material was pre-dried at 60°C to a moisture content of less than 5%, and then dried at 110°C to a moisture content of less than 1% to obtain the cobalt-free NiMnAl precursor of the composite structure of Example 4, the chemical formula of which is 0.04(Ni 0.333 Mn 0.667 ) 0.8 Al 0.2 (OH)2(CO3) 0.1 0.96Ni 0.333 Mn 0.667 OOH.

[0095] This embodiment also provides a positive electrode material, and the preparation method thereof is as follows: the precursor material obtained in step ④ and lithium hydroxide are mixed in a molar ratio of 1:1.12, and sintered at 950° C. in an oxygen atmosphere for 5 hours to obtain the positive electrode material.

[0096] This embodiment also provides a battery, in which the positive electrode material obtained in this embodiment is assembled into a button-type battery according to conventional methods in the art.

[0097] Example 5

[0098] This embodiment first provides a cobalt-free NiMnAl precursor, the preparation method of which includes the following steps:

[0099] ① Preparation of feed solution: Dissolve nickel sulfate, manganese sulfate, and aluminum nitrate in deionized water at a stoichiometric molar ratio of Ni:Mn:Al = 0.331:0.661:0.008 to prepare a mixed metal ion solution with a total metal ion concentration of 2 mol / L. Add industrial-grade liquid caustic soda to water to prepare a 10 mol / L precipitant solution. Dissolve concentrated ammonia in water to prepare a 6 mol / L complexing agent solution.

[0100] ② Coprecipitation reaction: 80L of water and an appropriate amount of ammonia water and alkali solution were added to a 100L reactor, the ammonia concentration was adjusted to 0.018mol / L, the pH value was 11.00-11.20, the reaction temperature was 50°C, and the stirring speed was 450r / min; and the mixed metal ion salt solution, alkali solution and ammonia solution were pumped into the reactor for coprecipitation reaction, and hydrogen peroxide was introduced at the same time. The molar concentration of hydrogen peroxide in the system was 3.0% of the total metal ion concentration in the mixed metal salt solution. The flow rate of the mixed metal salt solution was 160mL / min. The alkali solution and ammonia solution were pumped in to adjust the pH value of the system to 10.25 and the ammonia concentration to 0.018mol / L to stably control the particles to be maintained in the range of 3.0-5.0 microns. The residence time of the slurry in the reactor was controlled to be 14-15 hours. During the reaction, due to the oxidizing effect of the oxidant, part of the divalent manganese in the precipitation material was oxidized to trivalent manganese, and the color of the material was light brown. The Lab values ​​of an appropriate amount of slurry measured by a colorimeter were 44.6, 2.4, and 23.2, respectively. The precipitation reaction slurry was discharged into the aging tank through the overflow port.

[0101] ③ After the material flowing into the aging tank is separated, 100L of dilute alkali for aging is used for 100kg of material, and it is aged for 30 minutes in a 5% sodium hydroxide solution at 70℃ and washed until the supernatant of the slurry is neutral, and then separated and dewatered.

[0102] ④ The dehydrated material was pre-dried at 60°C to a moisture content of less than 5%, and then dried at 110°C to a moisture content of less than 1% to obtain the cobalt-free NiMnAl precursor of the composite structure of Example 5, the chemical formula of which is 0.04(Ni 0.333 Mn 0.667 ) 0.8 Al 0.2 (OH)2(CO3) 0.1 0.96Ni 0.333 Mn 0.667 OOH, its SEM picture is as follows Figure 3 As shown in the figure, the morphology of the precursor is a secondary particle formed by the accumulation of multiple thin-sheet nano primary particles. The nanosheets are small and uniform, with small pores between the sheets. There are no irregular particles (impurities) on the surface of the secondary particles. The XRD pattern is shown in the figure. Figure 4 As shown, according to the XRD pattern, the precursor is composed of the main phase β-MOOH and the auxiliary phase α, among which 19°, 34°, and 38° correspond to the β-MOOH phase; 11° and 23° correspond to the α phase.

[0103] This embodiment also provides a positive electrode material, and the preparation method thereof is as follows: the precursor material obtained in step ④ and lithium hydroxide are mixed in a molar ratio of 1:1.12, and sintered at 950° C. in an oxygen atmosphere for 5 hours to obtain the positive electrode material.

[0104] This embodiment also provides a battery, in which the positive electrode material obtained in this embodiment is assembled into a button-type battery according to conventional methods in the art.

[0105] Example 6

[0106] This embodiment first provides a cobalt-free NiMnAl precursor, the preparation method of which includes the following steps:

[0107] ① Preparation of feed solution: Dissolve nickel sulfate, manganese sulfate, and aluminum nitrate in deionized water at a stoichiometric molar ratio of Ni:Mn:Al = 0.331:0.661:0.008 to prepare a mixed metal ion solution with a total metal ion concentration of 2 mol / L. Add industrial-grade liquid caustic soda to water to prepare a 10 mol / L precipitant solution. Dissolve concentrated ammonia in water to prepare a 6 mol / L complexing agent solution.

[0108] ② Coprecipitation reaction: 80L of water and an appropriate amount of ammonia water and alkali solution were added to a 100L reactor, the ammonia concentration was adjusted to 0.018mol / L, the pH value was 11.00-11.20, the reaction temperature was 50°C, and the stirring speed was 450r / min; and the mixed metal ion salt solution, alkali solution and ammonia solution were pumped into the reactor for coprecipitation reaction, and an aqueous solution of sodium persulfate was introduced at the same time. The molar concentration of sodium persulfate in the system was 4.2% of the total metal ion concentration in the mixed metal salt solution. The flow rate of the mixed metal salt solution was 160mL / min. The alkali solution and ammonia solution were pumped in to adjust the pH value of the system to 10.15 and the ammonia concentration to 0.018mol / L to stably control the particles to be maintained in the range of 3.0-5.0 microns. The residence time of the slurry in the reactor was controlled to be 14-15 hours. During the reaction, due to the oxidizing effect of the oxidant, part of the divalent manganese in the precipitation material was oxidized to trivalent manganese, and the color of the material was light brown. The Lab values ​​of an appropriate amount of slurry measured by a colorimeter were 40.9, 0.9, and 25.0, respectively. The precipitation reaction slurry was discharged into the aging tank through the overflow port.

[0109] ③ After the material flowing into the aging tank is separated, 100L of dilute alkali for aging is used for 100kg of material, and it is aged for 30 minutes in a 5% sodium hydroxide solution at 70℃ and washed until the supernatant of the slurry is neutral, and then separated and dewatered.

[0110] ④ The dehydrated material was pre-dried at 60°C to a moisture content of less than 5%, and then dried at 110°C to a moisture content of less than 1% to obtain the cobalt-free NiMnAl precursor of the composite structure of Example 6, the chemical formula of which is 0.04(Ni 0.333 Mn 0.667 ) 0.8 Al 0.2 (OH)2(CO3) 0.1 0.96Ni 0.333Mn 0.667 OOH.

[0111] This embodiment also provides a positive electrode material, and the preparation method thereof is as follows: the precursor material obtained in step ④ and lithium hydroxide are mixed in a molar ratio of 1:1.12, and sintered at 950° C. in an oxygen atmosphere for 5 hours to obtain the positive electrode material.

[0112] This embodiment also provides a battery, in which the positive electrode material obtained in this embodiment is assembled into a button-type battery according to conventional methods in the art.

[0113] Example 7

[0114] This embodiment first provides a cobalt-free NiMnAl precursor, the preparation method of which includes the following steps:

[0115] ① Preparation of feed solution: Dissolve nickel sulfate, magnesium sulfate, manganese sulfate, and aluminum chloride in deionized water at a stoichiometric molar ratio of Ni:Mg:Mn:Al = 0.3465:0.004:0.6435:0.006 to prepare a mixed metal ion solution with a total metal ion concentration of 2 mol / L. Add industrial-grade liquid caustic soda to water to prepare a 10 mol / L precipitant solution. Dissolve concentrated ammonia in water to prepare a 6 mol / L complexing agent solution.

[0116] ② Coprecipitation reaction: 80L of water and an appropriate amount of ammonia water and alkali solution were added to a 100L reactor, the ammonia concentration was adjusted to 0.020mol / L, the pH value was 11.00-11.20, the reaction temperature was 52°C, and the stirring speed was 420r / min; and the mixed metal ion salt solution, alkali solution and ammonia solution were pumped into the reactor for coprecipitation reaction, and a mixed gas of nitrogen and air was introduced at 45L / h, the nitrogen / oxygen ratio was 5, and the molar concentration of oxygen in the system was 2.3% of the total metal ion concentration in the mixed metal salt solution. The flow rate of the mixed metal salt solution was 120mL / min, and the alkali solution and ammonia solution were pumped in to adjust the pH value of the system to 10.45 and the ammonia concentration to 0.020mol / L to stably control the particles to be maintained in the range of 3.0-5.0 microns. The residence time of the slurry in the reactor was controlled to be 14-15 hours. During the reaction, due to the oxidizing effect of the oxidant, part of the divalent manganese in the precipitation material is oxidized to trivalent manganese, and the material color is light brown. The precipitation reaction slurry is discharged into the aging tank through the overflow port.

[0117] ③ After the material flowing into the aging tank is separated, 100L of dilute alkali for aging is used for 100kg of material, and it is aged for 30 minutes in a 5% sodium hydroxide solution at 70℃ and washed until the supernatant of the slurry is neutral, and then separated and dewatered.

[0118] ④ The dehydrated material was pre-dried at 60°C to a moisture content of less than 5%, and then dried at 110°C to a moisture content of less than 1% to obtain the cobalt-free NiMnAl precursor of the composite structure of Example 7, the chemical formula of which is 0.036(Ni 0.348 Mg 0.004 Mn 0.648 ) 5 / 6 Al 1 / 6 (OH)2(CO3) 1 / 12 0.964Ni 0.348 Mg 0.004 Mn 0.648 OOH.

[0119] This embodiment also provides a positive electrode material, and the preparation method thereof is as follows: the precursor material obtained in step ④ and lithium hydroxide are mixed in a molar ratio of 1:1.12, and sintered at 950° C. in an oxygen atmosphere for 5 hours to obtain the positive electrode material.

[0120] This embodiment also provides a battery, in which the positive electrode material obtained in this embodiment is assembled into a button-type battery according to conventional methods in the art.

[0121] Example 8

[0122] This embodiment first provides a cobalt-free NiMnAl precursor, the preparation method of which includes the following steps:

[0123] ① Preparation of feed solution: Dissolve nickel sulfate, manganese sulfate, and aluminum chloride in deionized water at a stoichiometric molar ratio of Ni:Mn:Al = 0.3479:0.6461:0.006 to prepare a mixed metal ion solution with a total metal ion concentration of 2 mol / L. Add industrial-grade liquid caustic soda to water to prepare a 10 mol / L precipitant solution. Dissolve concentrated ammonia in water to prepare a 6 mol / L complexing agent solution.

[0124] ② Co-precipitation reaction: 80L of water and appropriate amounts of ammonia and alkali solution were added to a 100L reactor. The ammonia concentration was adjusted to 0.020 mol / L and the pH to 11.00-11.20. The reaction temperature was 52°C and the stirring speed was 420 r / min. The mixed metal ion salt solution, alkali solution, and ammonia solution were pumped into the reactor for a co-precipitation reaction. Hydrogen peroxide was simultaneously introduced. The molar concentration of hydrogen peroxide in the system was 3.4% of the total metal ion concentration in the mixed metal salt solution. The mixed metal salt solution flow rate was 120mL / min. The alkali solution and ammonia solution were pumped in to adjust the pH of the system to 10.35 and the ammonia concentration to 0.020 mol / L to stably control the particle size within the range of 3.0-5.0 microns. The residence time of the slurry in the reactor was controlled to 14-15 hours. During the reaction, the divalent manganese in the precipitated material was partially oxidized to trivalent manganese due to the oxidizing effect of the oxidant, and the material color became light brown. The precipitation reaction slurry was discharged through the overflow port into the aging tank.

[0125] ③ After the material flowing into the aging tank is separated, 100L of dilute alkali for aging is used for 100kg of material, and it is aged for 30 minutes in a 5% sodium hydroxide solution at 70℃ and washed until the supernatant of the slurry is neutral, and then separated and dewatered.

[0126] ④ The dehydrated material was pre-dried at 60°C to a moisture content of less than 5%, and then dried at 110°C to a moisture content of less than 1% to obtain the cobalt-free NiMnAl precursor of the composite structure of Example 8, the chemical formula of which is 0.036(Ni 0.35 Mn 0.65 ) 5 / 6Al 1 / 6 (OH)2(CO3) 1 / 12 0.964Ni 0.35 Mn 0.65 OOH.

[0127] This embodiment also provides a positive electrode material, and the preparation method thereof is as follows: the precursor material obtained in step ④ and lithium hydroxide are mixed in a molar ratio of 1:1.12, and sintered at 950° C. in an oxygen atmosphere for 5 hours to obtain the positive electrode material.

[0128] This embodiment also provides a battery, in which the positive electrode material obtained in this embodiment is assembled into a button-type battery according to conventional methods in the art.

[0129] Example 9

[0130] This embodiment first provides a cobalt-free NiMnAl precursor, the preparation method of which includes the following steps:

[0131] ① Preparation of feed solution: Dissolve nickel sulfate, manganese sulfate, and aluminum chloride in deionized water at a stoichiometric molar ratio of Ni:Mn:Al = 0.3479:0.6461:0.006 to prepare a mixed metal ion solution with a total metal ion concentration of 2 mol / L. Add industrial-grade liquid caustic soda to water to prepare a 10 mol / L precipitant solution. Dissolve concentrated ammonia in water to prepare a 6 mol / L complexing agent solution.

[0132] ② Coprecipitation reaction: 80L of water and an appropriate amount of ammonia and alkali solution were added to a 100L reactor, the ammonia concentration was adjusted to 0.020mol / L, the pH value was 11.00-11.20, the reaction temperature was 52°C, and the stirring speed was 420r / min; and the mixed metal ion salt solution, alkali solution and ammonia solution were pumped into the reactor for coprecipitation reaction, and an aqueous solution of sodium persulfate was introduced at the same time. The molar concentration of sodium persulfate in the system was 4.3% of the total metal ion concentration in the mixed metal salt solution. The flow rate of the mixed metal salt solution was 120mL / min. The alkali solution and ammonia solution were pumped in to adjust the pH value of the system to 10.25 and the ammonia concentration to 0.020mol / L to stably control the particles to be maintained in the range of 3.0-5.0 microns. The residence time of the slurry in the reactor was controlled to be 14-15 hours. During the reaction, due to the oxidizing effect of the oxidant, part of the divalent manganese in the precipitation material is oxidized to trivalent manganese, and the material color is light brown. The precipitation reaction slurry is discharged into the aging tank through the overflow port.

[0133] ③ After the material flowing into the aging tank is separated, 100L of dilute alkali for aging is used for 100kg of material, and it is aged for 30 minutes in a 5% sodium hydroxide solution at 70℃ and washed until the supernatant of the slurry is neutral, and then separated and dewatered.

[0134] ④ The dehydrated material was pre-dried at 60°C to a moisture content of less than 5%, and then dried at 110°C to a moisture content of less than 1% to obtain the cobalt-free NiMnAl precursor of the composite structure of Example 9, the chemical formula of which is 0.036(Ni 0.35 Mn 0.65 ) 5 / 6Al 1 / 6 (OH)2(CO3) 1 / 12 0.964Ni 0.35 Mn 0.65 OOH.

[0135] This embodiment also provides a positive electrode material, and the preparation method thereof is as follows: the precursor material obtained in step ④ and lithium hydroxide are mixed in a molar ratio of 1:1.12, and sintered at 950° C. in an oxygen atmosphere for 5 hours to obtain the positive electrode material.

[0136] This embodiment also provides a battery, in which the positive electrode material obtained in this embodiment is assembled into a button-type battery according to conventional methods in the art.

[0137] Comparative Example 1

[0138] This comparative example first provides a cobalt-free NiMn precursor, the preparation method of which comprises the following steps:

[0139] ① Preparation of feed solution: Dissolve nickel sulfate and manganese sulfate in deionized water at a stoichiometric molar ratio of Ni:Mn = 0.28:0.72 to prepare a mixed metal ion solution with a total metal ion concentration of 2 mol / L. Add industrial-grade liquid caustic soda to water to prepare a 10 mol / L precipitant solution. Dissolve concentrated ammonia in water to prepare a 6 mol / L complexing agent solution.

[0140] ② Co-precipitation reaction: Add 80L of water and appropriate amounts of ammonia and alkali to a 100L reactor. Adjust the ammonia concentration to 0.015mol / L and the pH to 11.00-11.20. The reaction temperature is 45°C and the stirring speed is 500r / min. Pump the mixed metal ion salt solution, alkali solution, and ammonia solution into the reactor for co-precipitation reaction at a flow rate of 240mL / min. Pump the alkali solution and ammonia solution into the reactor to adjust the pH to 10.20 and the ammonia concentration to 0.015mol / L to stably control the particle size within the range of 3.0-5.0 microns. The residence time of the slurry in the reactor is controlled at 14-15 hours. The precipitation reaction slurry is discharged through the overflow port into the aging tank.

[0141] ③ After the material flowing into the aging tank is separated, it is aged in a 5% sodium hydroxide solution at 70°C for 30 minutes and washed until the supernatant of the slurry is neutral, and then separated and dewatered.

[0142] ④ The dehydrated material was dried at 110°C until the moisture content was below 1% to obtain the cobalt-free NiMn precursor of Comparative Example 1, the SEM image of which is shown in FIG. Figure 5 As shown in the figure, the morphology of the precursor is a secondary particle formed by the accumulation of multiple thin-sheet nano primary particles. The nanosheets are coarse and uneven, with large pores between the sheets. There are irregular particles (mixed phase) adhering to the surface of the secondary particles. The XRD pattern is shown in Figure 6 As shown, according to the XRD pattern, the precursor is composed of the main phase β-MOOH and the auxiliary phase M3O4, among which 19°, 34°, and 38° correspond to the β-MOOH phase; 18°, 29°, 31°, 33°, 36°, and 45° correspond to the M3O4 phase.

[0143] This comparative example also provides a positive electrode material, and its preparation method is as follows: the precursor material obtained in step ④ and lithium hydroxide are mixed in a molar ratio of 1:1.12, and sintered at 950° C. in an oxygen atmosphere for 5 hours to obtain a positive electrode material.

[0144] This comparative example also provides a battery, in which the positive electrode material obtained in this comparative example is assembled into a button-type battery according to a conventional method in the art.

[0145] Comparative Example 2

[0146] This comparative example first provides a cobalt-free NiMn precursor, the preparation method of which comprises the following steps:

[0147] ① Preparation of feed solution: Dissolve nickel sulfate and manganese sulfate in deionized water at a stoichiometric molar ratio of Ni:Mn = 0.333:0.667 to prepare a mixed metal ion solution with a total metal ion concentration of 2 mol / L. Add industrial-grade liquid caustic soda to water to prepare a 10 mol / L precipitant solution. Dissolve concentrated ammonia in water to prepare a 6 mol / L complexing agent solution.

[0148] ② Co-precipitation reaction: Add 80L of water and appropriate amounts of ammonia and alkali to a 100L reactor. Adjust the ammonia concentration to 0.018mol / L and the pH to 11.00-11.20. The reaction temperature is 50°C and the stirring speed is 450r / min. Pump the mixed metal ion salt solution, alkali solution, and ammonia solution into the reactor for co-precipitation reaction at a flow rate of 160mL / min. Pump the alkali solution and ammonia solution into the reactor to adjust the pH to 10.25 and the ammonia concentration to 0.018mol / L to stably control the particle size within the range of 3.0-5.0 microns. The residence time of the slurry in the reactor is controlled at 14-15 hours. The precipitation reaction slurry is discharged through the overflow port into the aging tank.

[0149] ③ After the material flowing into the aging tank is separated, it is aged in a 5% sodium hydroxide solution at 70°C for 30 minutes and washed until the supernatant of the slurry is neutral, and then separated and dewatered.

[0150] ④ The dehydrated material was dried at 110°C until the moisture content was below 1% to obtain the cobalt-free NiMn precursor of Comparative Example 2, the SEM image of which is shown in FIG. Figure 7 As shown in the figure, the morphology of the precursor is a secondary particle formed by the accumulation of multiple thin-sheet nano primary particles. The nanosheets are coarse and uneven, with large pores between the sheets. There are irregular particles (mixed phase) adhering to the surface of the secondary particles. The XRD pattern is shown in Figure 8As shown, according to the XRD pattern, the precursor is composed of the main phase β-MOOH and the auxiliary phase M3O4, among which 19°, 34°, and 38° correspond to the β-MOOH phase; 18°, 29°, 31°, 33°, 36°, and 45° correspond to the M3O4 phase.

[0151] This comparative example also provides a positive electrode material, and its preparation method is as follows: the precursor material obtained in step ④ and lithium hydroxide are mixed in a molar ratio of 1:1.12, and sintered at 950° C. in an oxygen atmosphere for 5 hours to obtain a positive electrode material.

[0152] This comparative example also provides a battery, in which the positive electrode material obtained in this comparative example is assembled into a button-type battery according to a conventional method in the art.

[0153] Comparative Example 3

[0154] This comparative example first provides a cobalt-free NiMn precursor, the preparation method of which comprises the following steps:

[0155] ① Preparation of feed solution: Dissolve nickel sulfate and manganese sulfate in deionized water at a stoichiometric molar ratio of Ni:Mn = 0.35:0.65 to prepare a mixed metal ion solution with a total metal ion concentration of 2 mol / L. Add industrial-grade liquid caustic soda to water to prepare a 10 mol / L precipitant solution. Dissolve concentrated ammonia in water to prepare a 6 mol / L complexing agent solution.

[0156] ② Co-precipitation reaction: Add 80L of water and appropriate amounts of ammonia and alkali to a 100L reactor. Adjust the ammonia concentration to 0.020mol / L and the pH to 11.00-11.20. The reaction temperature is 52°C and the stirring speed is 420r / min. Pump the mixed metal ion salt solution, alkali solution, and ammonia solution into the reactor for co-precipitation reaction at a flow rate of 120mL / min. Pump the alkali solution and ammonia solution into the reactor to adjust the pH to 10.35 and the ammonia concentration to 0.020mol / L to stably control the particle size within the range of 3.0-5.0 microns. The residence time of the slurry in the reactor is controlled at 14-15 hours. The precipitation reaction slurry is discharged through the overflow port into the aging tank.

[0157] ③ After the material flowing into the aging tank is separated, it is aged in a 5% sodium hydroxide solution at 70°C for 30 minutes and washed until the supernatant of the slurry is neutral, and then separated and dewatered.

[0158] ④ The dehydrated material was dried at 110° C. until the moisture content was below 1% to obtain the cobalt-free NiMn precursor of Comparative Example 3.

[0159] This comparative example also provides a positive electrode material, and its preparation method is as follows: the precursor material obtained in step ④ and lithium hydroxide are mixed in a molar ratio of 1:1.12, and sintered at 950° C. in an oxygen atmosphere for 5 hours to obtain a positive electrode material.

[0160] This comparative example also provides a battery, in which the positive electrode material obtained in this comparative example is assembled into a button-type battery according to a conventional method in the art.

[0161] The D50, TD and the first discharge capacity of the corresponding batteries of the precursors of the composite structures prepared in Examples 1 to 9 and Comparative Examples 1 to 3 were detected and analyzed.

[0162] D50 test method: Disperse an appropriate amount of powder material in water and use the ultrasonic disperser of the Mastersizer 3000 to disperse for 30 seconds, then perform the particle size test according to the procedure.

[0163] TD test method: put 20g of powder material into the 50mL graduated cylinder that comes with the tap density meter and fix it. After sealing, start the motor to vibrate. Stop the vibration after 5 minutes and record the reading of the graduated cylinder to obtain the tap density of the powder.

[0164] First discharge capacity: Charge at 0.1C constant current to 4.55V in the voltage range of 2.5V to 4.55V at 25℃, then charge at constant voltage to a cutoff current of 0.02C at 4.55V, wait for 5 minutes, discharge at 0.1C or 1 / 3C to 2.5V, wait for 5 minutes, and record the charge and discharge capacity after the first cycle.

[0165] The test results are shown in Table 1.

[0166] Table 1 Physicochemical parameters and electrochemical properties of the precursors of Examples 1 to 9 and Comparative Examples 1 to 3

[0167]

[0168] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

[0169] Furthermore, those skilled in the art will appreciate that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and to form distinct embodiments. For example, in the claims above, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is intended solely to enhance understanding of the overall background of this application and should not be construed as an admission or any implication that such information constitutes prior art known to those skilled in the art.

Claims

1. A cobalt-free NiMnAl precursor of a composite structure, characterized in that: The cobalt-free NiMnAl precursor of the composite structure is composed of a monoclinic β-MOOH phase and a hexagonal α phase; The chemical formula of the monoclinic β-MOOH phase of the cobalt-free NiMnAl precursor of the composite structure is Ni x-τ M τ Mn 1-x OOH, the chemical formula of the hexagonal α phase is (Ni x-τ M τ Mn 1-x ) 1-t Al t (OH)2(CO3) t / 2 , wherein M is one or more of Ca, Mg, Fe, Cu, Zn, and Cd, τ<0.01, 0.25<x<0.50, 1 / 6≤t≤1 / 4; The cobalt-free NiMnAl precursor of the composite structure has no tetragonal phase (Ni x Mn 1-x )3O4.

2. The cobalt-free NiMnAl precursor of the composite structure according to claim 1, characterized in that: The cobalt-free NiMnAl precursor of the composite structure includes secondary particles formed by stacking a plurality of flaky nano primary particles, wherein the secondary particles meet at least one of the following conditions: A. The particle size D50 of the secondary particles is 3 to 5 μm; B. The tap density of the secondary particles is 1.0~1.55g / cm 3 .

3. The cobalt-free NiMnAl precursor of the composite structure according to claim 1, characterized in that: At least one of the following conditions is met: A. The monoclinic β-MOOH phase satisfies the following conditions: a = 5.35-5.66 Å, b = 2.89-2.94 Å, c = 4.80-4.90 Å, α = 90°, β = 108-109°, and γ = 90°; B. The hexagonal α phase satisfies the following conditions: a = b = 3.00-3.14 Å, c = 23.4-24.0 Å, α = 90°, β = 90°, γ = 120°; C. Na of the cobalt-free NiMnAl precursor of the composite structure is less than 120 ppm; D. The S content of the cobalt-free NiMnAl precursor of the composite structure is less than 1800 ppm.

4. The cobalt-free NiMnAl precursor of the composite structure according to any one of claims 1 to 3, characterized in that: The content of the hexagonal α phase of the cobalt-free NiMnAl precursor of the composite structure is m, and the content of the monoclinic β-MOOH phase is 1-m. The overall chemical formula of the cobalt-free NiMnAl precursor of the composite structure is: m(Ni x-τ M τ Mn 1-x ) 1-t Al t (OH)2(CO3) t / 2 ·(1-m)Ni x-τ M τ Mn 1-x OOH, wherein 0.005<mt<0.01, 0.035<m<0.

06.

5. A method for preparing a cobalt-free NiMnAl precursor of a composite structure according to any one of claims 1 to 4, characterized in that: include: Passing a mixed metal salt solution, a precipitant, a complexing agent, and an oxidant into the bottom liquid of a reactor to perform a co-precipitation reaction to obtain a slurry, and separating the slurry to obtain a solid precipitate; The solid precipitate and the aging solution are mixed to carry out aging reaction and washing to obtain an aged product; The aged product is sequentially subjected to a first drying process to a moisture content of less than 5% and a second drying process to a moisture content of less than 1%, wherein the temperature of the first drying process is lower than the temperature of the second drying process, to obtain the cobalt-free NiMnAl precursor of the composite structure.

6. The method for preparing a cobalt-free NiMnAl precursor of a composite structure according to claim 5, characterized in that: At least one of the following conditions is met: A. the molar concentration of the oxidant in the coprecipitation reaction system is less than 5% of the total metal ion concentration in the mixed metal salt solution; B. the temperature of the coprecipitation reaction is 45 to 55° C.; C. the pH of the coprecipitation reaction is 9.9 to 11.5; D. the stirring speed of the coprecipitation reaction is 400-500 rpm; E. The oxidant comprises one or more of sodium hypochlorite, sodium persulfate, hydrogen peroxide, compressed air or a nitrogen / air mixture; F. the molar concentration of the complexing agent in the coprecipitation reaction system is less than 1% of the total metal ion concentration in the mixed metal salt solution; G. The color of the slurry was quantitatively measured by Lab colorimeter, with L value of 40-50, a value of 0-4, and b value of 20-25; H. The flow rate of the mixed metal salt solution is 80~360mL / min.

7. The method for preparing a cobalt-free NiMnAl precursor of a composite structure according to claim 5 or 6, characterized in that: At least one of the following conditions is met: A. The mixed metal salt solution is a soluble salt solution of nickel, manganese and aluminum metals, and the soluble salt includes one or more soluble sulfates, nitrates, acetates or chlorides; B. the total metal ion concentration in the mixed metal salt solution is 0.5 to 4 mol / L; C. the precipitant comprises one or more of sodium hydroxide, sodium carbonate, potassium hydroxide, and lithium hydroxide; D. the concentration of the precipitant is 1 to 10 mol / L; E. the complexing agent includes one or more of ammonia water, ammonium sulfate, ammonium carbonate, and ammonium bicarbonate; F. The concentration of the complexing agent is 0.1 to 5 mol / L; G. the aging solution comprises one or more of sodium hydroxide, sodium carbonate, and sodium bicarbonate; H. the temperature of the first drying is not higher than 60°C; I. The temperature of the second drying is not higher than 110°C.

8. A positive electrode material, characterized in that It is prepared from the cobalt-free NiMnAl precursor of the composite structure according to any one of claims 1 to 4.

9. A lithium-ion battery, characterized in that: Comprising the positive electrode material according to claim 8.

10. An electrical device, characterized in that: Including the lithium ion battery according to claim 9.

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