CN116072857A - Niobium-phosphorus co-doped nickel-cobalt-manganese lithium aluminate quaternary material, preparation method thereof and lithium ion battery containing same - Google Patents

Abstract

The present disclosure relates to a niobium-phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material, a preparation method thereof, and a lithium ion battery containing the same, wherein the niobium-phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material contains a compound having a chemical formula of LiNi _x Co _y Mn _z Al _w Nb _n P _m O ₂ X+y+z+w+n+m=1, y is 0 < 0.2, z is 0 < 0.1, w is 0 < 0.05,0.002 < n is 0.02,0.001 < m is 0.02; a is that _Nb And D _Nb Has a ratio of 0.9 to 1.1, A _P And D _P The ratio of (2) is 5-15. The niobium-phosphorus co-doped nickel cobalt manganese lithium aluminate quaternary material has phosphorus element enriched in the particlesAnd the niobium element is uniformly distributed on the surface of the particle body phase. The distribution mode of the phosphorus element and the niobium element can improve the cycling stability of the material and relieve the corrosion of the electrolyte to the material.

Description

Niobium-phosphorus co-doped nickel-cobalt-manganese lithium aluminate quaternary material, preparation method thereof and lithium ion battery containing same

Technical Field

The disclosure relates to the field of preparation of positive electrode materials of lithium ion batteries, in particular to a niobium-phosphorus co-doped nickel-cobalt-manganese lithium aluminate quaternary material, a preparation method thereof and a lithium ion battery containing the same.

Background

Lithium ion batteries have received a great deal of attention from various industries since commercialization, and are currently the dominant energy suppliers of new energy automobiles. The lithium ion battery anode material is used as a core component of the battery and a bottleneck of energy density, and the performance of the lithium ion battery anode material directly influences various performance indexes of the lithium ion battery, so that the lithium ion battery anode material has the advantages of high specific capacity, good safety and long cycle life. As a kind of layered anode materials, the NCMA has the advantages of high specific capacity, good safety performance and the like. However, the nickel cobalt manganese lithium aluminate material suffers from the defects of poor circulation stability, insufficient thermal stability and the like due to the defects of the layered high nickel material such as insufficient structural stability, higher surface residual alkali and the like. Elemental doping is one of the methods that effectively improves the structural stability and surface stability of layered materials.

The niobium-phosphorus element co-doping method combines the advantages of each doping element, and further improves the cycle performance of the material. After preparing a nickel-cobalt-manganese ternary precursor by a conventional coprecipitation method, the patent CN110085858A prepares the niobium-phosphorus co-doped nickel-cobalt-manganese ternary positive electrode material by two-step plasma roasting, improves the structural stability of the material, and reduces the residual alkali on the surface. However, the coprecipitation synthesis method of the nickel-cobalt-aluminum ternary system has strict requirements on reaction conditions, and in addition, the method adopts professional devices such as a conventional coprecipitation method ternary precursor, a plasma enhanced rotary furnace and the like, has high equipment requirements, is not beneficial to industrial production, and is not beneficial to diffusion of doped ions in ternary materials only through simple surface coating and roasting.

Disclosure of Invention

The invention aims to provide a niobium-phosphorus co-doped nickel cobalt manganese lithium aluminate quaternary material, a preparation method thereof and a lithium ion battery comprising the same.

To achieve the above object, a first aspect of the present disclosure provides a niobium-phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material, which comprises a material having a chemical formula LiNi _x Co _y Mn _z Al _w Nb _n P _m O ₂ X+y+z+w+n+m=1, y is 0 < 0.2, z is 0 < 0.1, w is 0 < 0.05,0.002 < n is 0.02,0.001 < m is 0.02;

wherein A is _Nb And D _Nb Has a ratio of 0.9 to 1.1, A _P And D _P The ratio of (2) is 5-15;

a is based on the total mole of nickel element, cobalt element, manganese element, aluminum element, niobium element and phosphorus element on the surface of the particle _Nb Representing the molar ratio of niobium element on the surface of the particles, A _P A molar ratio of phosphorus element representing the surface of the particles;

d based on the total mole of nickel element, cobalt element, manganese element, aluminum element, niobium element and phosphorus element in the particle body phase _Nb Represents the molar ratio of niobium element in the bulk phase of the particles, D _P Representing the molar ratio of phosphorus element in the bulk phase of the particles.

Optionally, the particles have a median particle diameter D50 of 8-12 μm.

A second aspect of the present disclosure provides a method of preparing a niobium phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material according to the first aspect of the present disclosure, the method comprising the steps of:

(1) Carrying out first ball milling on the aluminum-based hydrotalcite nano-sheet, the nickel-cobalt-manganese ternary precursor and the niobium-containing compound to obtain a first pre-product;

(2) Performing second ball milling on the first pre-product and a lithium-containing compound, and performing first heat treatment under a first oxygen-containing atmosphere to obtain a second pre-product;

(3) Performing third ball milling on the second pre-product and the first phosphorus-containing compound;

(4) Carrying out second heat treatment on the third pre-product obtained in the step (3) and a second phosphorus-containing compound in an inert atmosphere;

(5) Carrying out third heat treatment on the fourth pre-product obtained in the step (4) in a second oxygen-containing atmosphere;

wherein the aluminum-based hydrotalcite nano-sheet comprises transition metal, the transition metal is cobalt element or nickel element, and the mol ratio of the transition metal element to the aluminum element is (2-5): 1.

Optionally, in the step (1), the molar ratio of the transition element in the aluminum-based hydrotalcite nano-sheet to the niobium element in the niobium-containing compound is 2:1 or more.

Optionally, the chemical formula of the nickel-cobalt-manganese ternary precursor is Ni _1-a-b Co _a Mn _b (OH) ₂ Or Ni _{1-a- b} Co _a Mn _b CO ₃ Wherein a is more than 0 and less than or equal to 0.1, b is more than 0 and less than or equal to 0.1;

optionally, the median particle diameter D50 of the nickel-cobalt-manganese ternary precursor is 8-12 μm.

Optionally, the niobium-containing compound comprises one or more of niobium pentoxide, niobium oxalate and ammonium niobium oxalate;

the lithium-containing compound comprises one or more of lithium hydroxide, lithium carbonate and lithium nitrate;

the first phosphorus-containing compound comprises one or more of ammonium phosphate, diammonium phosphate and monoammonium phosphate;

the second phosphorus-containing compound comprises phosphite and/or hypophosphite;

optionally, the phosphite comprises sodium phosphite and/or ammonium phosphite;

the hypophosphite comprises sodium hypophosphite and/or ammonium hypophosphite;

optionally, the molar ratio of the first phosphorus-containing compound to the second pre-product is (0.5-4): 100;

the molar ratio of the second phosphorus-containing compound to the third pre-product is 1: (2-50).

Optionally, the niobium-containing compound has an average particle size of 50 to 80nm; the average particle diameter of the lithium-containing compound is 6-8 mu m; the first phosphorus-containing compound has an average particle diameter of 5-10 μm.

Optionally, in step (2), the molar ratio of the total molar sum of nickel element, cobalt element, manganese element, aluminum element and niobium element in the first pre-product to lithium element in the lithium-containing compound is 1 (1.0-1.1).

Optionally, in step (2), the first heat treatment includes the steps of:

a. heating to 500-600 ℃ at a first heating rate of 1-8 ℃/min, and performing first roasting for 1-3h;

b. continuously heating to 700-800 ℃ at a second heating rate of 2-6 ℃/min, and performing second roasting for 10-15h.

Optionally, the time of the first ball milling is 1-4h; the second ball milling time is 1-4h, and the third ball milling time is 1-4h.

Optionally, step (4) is performed in a tube furnace, placing the second phosphorus-containing compound upstream of the tube furnace, and placing the third pre-product downstream of the tube furnace.

Optionally, in step (4), the second heat treatment method is roasting, and the second heat treatment conditions include: the temperature is 200-400 ℃ and the time is 3-8h;

in the step (5), the third heat treatment method is roasting, and the third heat treatment conditions include: the temperature is 600-850 ℃ and the time is 3-8h.

Optionally, the inert atmosphere comprises nitrogen and/or argon;

the first oxygen-containing atmosphere and the second oxygen-containing atmosphere are the same or different, and are each independently an oxygen atmosphere and/or an air atmosphere.

A third aspect of the present disclosure provides a lithium ion battery comprising a positive electrode comprising the niobium-phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material of the first aspect of the present disclosure, an electrolyte, and a negative electrode.

Through the technical scheme, the aluminum-based hydrotalcite nano-sheet containing transition metal elements reacts with the niobium-containing compound and the nickel-cobalt-manganese ternary precursor under the condition of solid-phase ball milling, then the aluminum-based hydrotalcite nano-sheet is mixed with a lithium source for roasting, and finally the niobium-phosphorus co-doped nickel-cobalt-manganese lithium aluminate quaternary material is obtained through phosphorus doping. The method can reduce the synthesis difficulty of the material, improve the doping effect of the niobium element and the phosphorus element, and further improve the cycle performance of the material. The niobium element in the prepared quaternary material is uniformly distributed in the bulk phase, so that the structural distortion and structural collapse of the material in the charge and discharge process can be restrained, and the cycle stability is improved; the phosphorus element is enriched on the surface of the material, so that the corrosion of the electrolyte to the material is relieved, and finally, the effective improvement of the electrochemical cycle stability is realized.

Additional features and advantages of the present disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification, illustrate the disclosure and together with the description serve to explain, but do not limit the disclosure. In the drawings:

fig. 1 is a scanning electron microscope image of a niobium-phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material A1 prepared in example 1 of the present application.

Fig. 2 is a scanning electron microscope image of a niobium doped lithium nickel cobalt manganese aluminate quaternary material D1 prepared in comparative example 1 of the present application.

Fig. 3 is a scanning electron microscope image of the phosphorus-doped lithium nickel cobalt manganese aluminate quaternary material D2 prepared in comparative example 2 of the present application.

Fig. 4 is a scanning electron microscope image of the undoped nickel cobalt manganese lithium aluminate quaternary material D3 prepared in comparative example 3 of the present application.

Detailed Description

Specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the disclosure, are not intended to limit the disclosure.

The first aspect of the disclosure provides a niobium-phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary materialThe niobium-phosphorus co-doped nickel-cobalt-manganese lithium aluminate quaternary material comprises a chemical formula of LiNi _x Co _y Mn _z Al _w Nb _n P _m O ₂ X+y+z+w+n+m=1, y is 0 < 0.2, z is 0 < 0.1, w is 0 < 0.05,0.002 < n is 0.02,0.001 < m is 0.02;

wherein A is _Nb And D _Nb Has a ratio of 0.9 to 1.1, A _P And D _P The ratio of (2) is 5-15;

a is based on the total mole of nickel element, cobalt element, manganese element, aluminum element, niobium element and phosphorus element on the surface of the particle _Nb Representing the molar ratio of niobium element on the surface of the particles, A _P A molar ratio of phosphorus element representing the surface of the particles;

d based on the total mole of nickel element, cobalt element, manganese element, aluminum element, niobium element and phosphorus element in the particle body phase _Nb Represents the molar ratio of niobium element in the bulk phase of the particles, D _P Representing the molar ratio of phosphorus element in the bulk phase of the particles.

In a preferred embodiment, A _Nb And D _Nb Has a ratio of 0.95-1.05, A _P And D _P The ratio of (2) is 6-10. The niobium element of the material in the range is uniformly distributed in the bulk phase, so that the crystal structure of the material is further optimized, the structural distortion and structural collapse of the material in the charge and discharge process can be restrained, and the cycle stability is improved; the phosphorus element is enriched on the surface of the material, so that the corrosion of the electrolyte to the material is relieved, and finally, the effective improvement of the electrochemical cycle stability is realized.

In the present disclosure, "the mole ratio of the niobium element at the particle surface" means a ratio of the mole number of the niobium element at the particle surface to the total mole number of the nickel element, cobalt element, manganese element, aluminum element, phosphorus element and niobium element at the surface; "the molar ratio of the niobium element in the particulate body phase" means the ratio of the number of moles of the niobium element in the particulate body phase to the total number of moles of the nickel element, cobalt element, manganese element, aluminum element, phosphorus element and niobium element in the body phase; "the mole ratio of the phosphorus element on the surface of the particle" means the ratio of the mole number of the phosphorus element on the surface of the particle to the total mole number of the nickel element, cobalt element, manganese element, aluminum element, phosphorus element and niobium element on the surface; "molar ratio of phosphorus element in the particulate bulk phase" means the ratio of the number of moles of phosphorus element in the particulate bulk phase to the total number of moles of nickel element, cobalt element, manganese element, aluminum element, phosphorus element and niobium element in the bulk phase

In one embodiment of the present disclosure, the median particle diameter D50 of the particles is 8-12 μm, preferably 9-11 μm.

A second aspect of the present disclosure provides a method of preparing a niobium phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material according to the first aspect of the present disclosure, the method comprising the steps of:

(1) Carrying out first ball milling on the aluminum-based hydrotalcite nano-sheet, the nickel-cobalt-manganese ternary precursor and the niobium-containing compound to obtain a first pre-product;

(2) Performing second ball milling on the first pre-product and a lithium-containing compound, and performing first heat treatment under a first oxygen-containing atmosphere to obtain a second pre-product;

(3) Performing third ball milling on the second pre-product and the first phosphorus-containing compound;

(4) Carrying out second heat treatment on the third pre-product obtained in the step (3) and a second phosphorus-containing compound in an inert atmosphere;

(5) Carrying out third heat treatment on the fourth pre-product obtained in the step (4) in a second oxygen-containing atmosphere;

wherein the aluminum-based hydrotalcite nano-sheet comprises transition metal, the transition metal is cobalt element or nickel element, the mol ratio of the transition metal element to aluminum element is (2-5): 1, preferably (2-3): 1.

in the heat treatment process, cobalt element or nickel element in the aluminum-based hydrotalcite nano-sheet can drive niobium element into the material through a 'synergistic diffusion effect', so that the synthesis difficulty of the aluminum-based layered cathode material is reduced. And the chemical bond of Nb-O can be utilized to inhibit structural distortion and structural collapse of the material in the charge-discharge process, so that the cycling stability of the material is improved. Phosphorus element is mainly enriched on the particle surface, so that the surface structure damage caused in the alkali-reducing process of water washing can be reduced, and the coating effect can be achieved to relieve the corrosion of electrolyte to materials. In the method disclosed by the invention, the phosphorus doping is carried out in two modes of solid-phase diffusion and vapor deposition, so that the phosphorus doping effect and the surface phosphorus enrichment effect in the bulk phase of the material are both effectively improved, and the cycle performance of the material can be further improved by the synergistic effect of multiple phosphorus doping modes.

In the present disclosure, in order to remove surface impurities, step (4) further includes: and cooling the solid material obtained by the second heat treatment to room temperature, adding the solid material into water, stirring and washing for 10min, filtering and drying to obtain a fourth pre-product. The drying method is conventional in the art, and is not specifically required here.

In one embodiment of the disclosure, in the step (1), the molar ratio of the transition metal element in the aluminum-based hydrotalcite nanosheets to the niobium element in the niobium-containing compound is 2:1 or more, preferably 4:1 or more, and the content of the niobium element on the surface can be reduced by satisfying the above ratio, so that the prepared material has better electrochemical performance.

In one embodiment of the present disclosure, the nickel cobalt manganese ternary precursor is a high nickel hydroxide precursor having the chemical formula Ni _1-a-b Co _a Mn _b (OH) ₂ Alternatively, the ternary nickel-cobalt-manganese precursor is a carbonate precursor, and the chemical formula is Ni _{1-a- b} Co _a Mn _b CO ₃ The method comprises the steps of carrying out a first treatment on the surface of the Wherein a is more than 0 and less than or equal to 0.1, b is more than 0 and less than or equal to 0.1; further, the ternary nickel cobalt manganese precursor is spherical, and the median particle diameter D50 is 8-12 μm, preferably 9-11 μm.

In one embodiment of the present disclosure, the niobium-containing compound comprises one or more of niobium pentoxide, niobium oxalate, and ammonium niobium oxalate; the lithium-containing compound comprises one or more of lithium hydroxide, lithium carbonate and lithium nitrate; the first phosphorus-containing compound comprises one or more of ammonium phosphate, diammonium phosphate and monoammonium phosphate; the second phosphorus-containing compound comprises phosphite and/or hypophosphite; further, the phosphite includes sodium phosphite and/or ammonium phosphite; hypophosphite includes sodium hypophosphite and/or ammonium hypophosphite.

In one embodiment of the present disclosure, the molar ratio of the first phosphorus-containing compound to the second pre-product is (0.5-4): 100; preferably (1-2): 100.

in one embodiment of the present disclosure, the molar ratio of the second phosphorus-containing compound to the third pre-product is 1: (2-50); preferably 1: (5-20).

In one embodiment of the present disclosure, the niobium-containing compound has an average particle size of 50 to 80nm, preferably 50 to 60nm; the average particle diameter of the lithium-containing compound is 6 to 8. Mu.m, preferably 6 to 7. Mu.m; the average particle diameter of the first phosphorus-containing compound is 5 to 10. Mu.m, preferably 5 to 8. Mu.m.

In one embodiment of the present disclosure, in step (2), the molar ratio of the total molar sum of nickel element, cobalt element, manganese element, aluminum element and niobium element in the first pre-product to lithium element in the lithium-containing compound is 1 (1.0 to 1.1), preferably 1 (1.02 to 1.08), further preferably 1: (1.04-1.06).

In the present disclosure, in step (1), the feeding amounts of the aluminum-based hydrotalcite nanoplatelets, the nickel-cobalt-manganese ternary precursor and the niobium-containing compound are according to LiNi _x Co _y Mn _z Al _w Nb _n P _m O ₂ The molar ratio of Ni element, co element, mn element, al element and Nb element in the material is weighed, and the molar content of Ni element, co element, mn element, al element and Nb element in the final product can be met.

In one embodiment of the present disclosure, in step (2), the first heat treatment includes the steps of:

a. heating to 500-600 ℃ at a first heating rate of 1-8 ℃/min, and performing first roasting for 1-3h;

b. continuously heating to 700-800 ℃ at a second heating rate of 2-6 ℃/min, and performing second roasting for 10-15h. By adopting the heat treatment method, the nickel-cobalt-manganese ternary precursor, the aluminum-based hydrotalcite nano-sheet and the lithium-containing compound can be fully decomposed into oxides in the first roasting stage, so that the solid phase reaction efficiency in the second roasting stage is improved, and the layered material with more complete crystal forms is generated.

In one embodiment of the present disclosure, the first ball mill, the second ball mill, and the third ball mill are all solid phase ball mills. Further, the time of the first ball milling is 1 to 4 hours, preferably 2 to 3 hours; the second ball milling time is 1-4h, preferably 2-3h; the time for the third ball milling is 1 to 4 hours, preferably 2 to 3 hours. The ball milling time is satisfied, so that the full coating can be ensured, and precursor particles are prevented from being broken due to overlong ball milling time.

In one embodiment of the disclosure, step (4) is performed in a tube furnace, the second phosphorus-containing compound is placed upstream of the tube furnace, and the third pre-product is placed downstream of the furnace. Wherein the upstream and downstream are disposed opposite each other along a second phosphorus-containing compound, the second phosphorus-containing compound located upstream being decomposed at an elevated temperature, the gaseous phosphorus compound flowing downstream to react with a third pre-product. By adopting the method, phosphorus elements are doped into the quaternary material crystal lattice in a solid-phase diffusion mode and are enriched on the surfaces of the quaternary material particles in a vapor deposition mode, so that the structure and the surface stability of the material are improved.

In one embodiment of the present disclosure, in step (4), the method of the second heat treatment is firing, and the conditions of the second heat treatment include: the temperature is 200-400 ℃ and the time is 1-5h; preferably, the temperature is 300-400 ℃ and the time is 2-4 hours; in the step (5), the third heat treatment method is roasting, and the third heat treatment conditions include: the time is 600-850 ℃ and 3-8 hours; preferably, the temperature is 700-800 ℃ and the time is 3-5h.

In one embodiment of the present disclosure, the inert atmosphere comprises nitrogen and/or oxygen.

In one embodiment of the present disclosure, the first oxygen-containing atmosphere and the second oxygen-containing atmosphere are the same or different and are each independently an oxygen atmosphere and/or an air atmosphere. Specifically, the first oxygen-containing atmosphere and the second oxygen-containing atmosphere are both oxygen atmospheres.

In one embodiment of the present disclosure, the transition metal element-containing aluminum-based hydrotalcite nanoplatelets are prepared using the following steps:

s1, preparing a first solution containing a transition metal source and an aluminum source;

s2, adding the first solution and the alkali solution into a colloid mill, wherein the rotating speed is 1000-3000r/min, and the time is 2-5min, so as to obtain a suspension;

s3, preparing aluminum-based hydrotalcite nano-sheets by using the suspension;

further, preparing an aluminum-based hydrotalcite nanosheet using the suspension includes: aging the suspension for 2-4h under the water bath condition of 95-98 ℃, washing and filtering until the pH value is less than 7.5, and drying the solid obtained by filtering at 80-120 ℃ for 8-12h to obtain the aluminum-based hydrotalcite nano-sheet containing the transition metal element. The drying method is conventional in the art, and is not specifically required here.

In the present disclosure, the transition metal source is a soluble transition metal salt including one or more of nickel sulfate, nickel chloride, nickel nitrate, and nickel acetate; alternatively, the soluble transition metal salt comprises one or more of cobalt sulfate, cobalt chloride, cobalt nitrate and cobalt acetate.

In the present disclosure, the aluminum source includes one or more of aluminum sulfate, aluminum chloride, aluminum nitrate, and aluminum acetate, and may be, for example, aluminum sulfate.

In the present disclosure, the alkaline solution comprises a soluble base including sodium hydroxide and/or potassium hydroxide and a soluble alkaline salt; soluble alkaline salts include sodium carbonate and/or potassium carbonate; specifically, the soluble base is sodium hydroxide and the soluble alkaline salt includes sodium carbonate. Further, the concentration of the soluble alkali is 1-2mol/L, and the concentration of the soluble alkaline salt is 0.25-0.75mol/L.

In the present disclosure, the volume ratio of the first solution to the alkaline solution is (0.8-1.5): 1, a step of; for example, an equal volume mixing is possible.

In the present disclosure, the molar ratio of the transition metal source in terms of the transition metal element to the aluminum source in terms of the aluminum element is (2-5): 1, a step of; the total molar concentration of the transition metal source calculated as the transition metal element and the aluminum source calculated as the aluminum element is 0.5 to 1.25mol/L.

A third aspect of the present disclosure provides a lithium ion battery comprising a positive electrode comprising the niobium-phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material of the first aspect of the present disclosure, an electrolyte, and a negative electrode.

Further, the negative electrode material of the lithium ion battery may be, for example, a lithium sheet, and the electrolyte may be, for example, liPF ₆ Alkyl carbonate solution of (a). This is conventional in the art and is not specifically required here.

The reagents used in the examples and comparative examples of this application are both commercially available.

The model of a test instrument of the scanning electron microscope is FEI Quanta 200FEG, the rated voltage of equipment is 10kV, and different multiples are amplified for observation;

the median particle diameter D50 was measured using a Mastersizer2000 laser particle sizer from malvern, uk, and the nanomaterial particle diameter was measured using SEM labeling.

Material metal element analysis: particle surface elemental analysis was performed using a VG scientific company ESCALab220i-XL type X-ray photoelectron spectroscopy, and particle bulk elemental analysis was performed using a Perkin-Elmer Optima 3300DV Inductively Coupled Plasma (ICP) elemental analyzer.

The first discharge capacity and the capacity retention rate are tested by adopting a Wuhan blue electric CT2001A battery tester, and the charge-discharge voltage range is 2.7-4.3V (vs. Li) ⁺ /Li). After 0.1C is charged and discharged for 5 cycles, 0.2C is charged and discharged for 3 cycles, and finally 0.5C is subjected to long-period cycle.

In the following examples and comparative examples, the methods of the first ball milling, the second ball milling and the third ball milling were all solid phase ball milling.

Examples 1-6 are presented to illustrate niobium-phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary materials and methods of making the same.

Example 1

The niobium-phosphorus co-doped nickel cobalt manganese lithium aluminate quaternary material A1 is prepared by adopting the following steps.

(1) Preparation of cobalt-aluminum hydrotalcite nano-sheet

Dissolving cobalt sulfate calculated by Co element and aluminum sulfate calculated by Al element in a molar ratio of 3:1 into deionized water to prepare a first solution with total concentration of metal ions of 1.0 mol/L; an alkali solution having a sodium hydroxide concentration of 1.6mol/L and a sodium carbonate concentration of 0.25mol/L was prepared. Mixing the first solution with alkaliSimultaneously adding the liquid into a colloid mill with the rotating speed of 3000r/min according to the volume ratio of 1:1 for mixing reaction for 3min, stirring and aging the mixed suspension in a water bath with the temperature of 98 ℃ for 3h, repeatedly washing and filtering until the pH value of the filtrate is less than 7.5, drying the washed filter cake at the temperature of 120 ℃ for 10h to obtain cobalt-aluminum hydrotalcite nano-sheets with the cobalt-aluminum element molar ratio of 3:1, wherein the chemical formula is Co ₆ Al ₂ (OH) ₁₆ CO ₃ ·6H ₂ O。

(2) Niobium element doping

According to Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂ The precursor (with the median particle diameter D50 of 9.5 mu m), the cobalt aluminum hydrotalcite nano-sheet prepared in the step (1) and the nano niobium pentoxide (with the average particle diameter of 50 nm) are weighed as samples according to the molar ratio of 100:1:0.5, and the samples are subjected to first ball milling for 2.5 hours to obtain a first pre-product.

And respectively weighing the first pre-product and lithium hydroxide (with the average particle size of 7 mu m) according to the molar ratio of n (Ni+Co+Mn+Al+Nb) to n (Li) =1:1.06, performing second ball milling for 2.5 hours, then heating to 500 ℃ at a first heating rate of 2 ℃/min in an oxygen atmosphere, performing first roasting for 3 hours, continuously heating to 750 ℃ at a second heating rate of 2 ℃/min, performing second roasting for 15 hours, and cooling to room temperature to obtain a second pre-product.

(3) Doping of phosphorus element

Weighing the second pre-product and diammonium hydrogen phosphate (with the average particle size of 5 mu m) according to the molar ratio of 100:1, and performing third ball milling for 1.5 hours to obtain a third pre-product;

weighing a third pre-product and sodium hypophosphite according to the molar ratio of 20:1, placing sodium hypophosphite at the upstream of a tube furnace, placing the third pre-product at the downstream of the tube furnace, performing second heat treatment under nitrogen atmosphere in a manner of roasting for 2 hours at the temperature of 300 ℃, cooling to the room temperature, adding into water, stirring, washing for 10 minutes, filtering and drying to obtain a fourth pre-product;

and carrying out third heat treatment on the fourth pre-product in an oxygen atmosphere at 750 ℃ for 5 hours in a roasting mode to obtain the niobium-phosphorus co-doped nickel-cobalt-manganese lithium aluminate quaternary material A1, wherein the chemical formula, the median particle diameter D50 and the element distribution are shown in Table 1.

Scanning electron microscope tests are carried out on the niobium-phosphorus co-doped nickel cobalt manganese lithium aluminate quaternary material A1, and the results are shown in figure 1.

Example 2

The method of example 1 was used to prepare a niobium phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material A2, with the following differences:

(2) Niobium element doping

According to Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂ The precursor (with a median particle diameter D50 of 9.5 mu m), the cobalt-aluminum hydrotalcite nano-sheet prepared in the step (1) and niobium oxalate (with an average particle diameter of 50 nm) are weighed as samples according to a molar ratio of 100:2:1, and the samples are subjected to first ball milling for 2.5 hours to obtain a first pre-product.

And respectively weighing the first pre-product and lithium carbonate (with the average particle size of 6 mu m) according to the molar ratio of n (Ni+Co+Mn+Al+Nb) to n (Li) =1:1.05, performing second ball milling for 2.5 hours, then heating to 500 ℃ at a first heating rate of 4 ℃/min in an oxygen atmosphere, performing first roasting for 3 hours, continuously heating to 750 ℃ at a second heating rate of 4 ℃/min, performing second roasting for 15 hours, and cooling to room temperature to obtain a second pre-product.

(3) Doping of phosphorus element

Weighing the second pre-product and diammonium hydrogen phosphate (with the average particle size of 5 mu m) according to the molar ratio of 100:1, and performing third ball milling for 1.5 hours to obtain a third pre-product;

weighing a third pre-product and sodium phosphite according to the molar ratio of 10:1, placing sodium phosphite at the upstream of a tube furnace, placing the third pre-product at the downstream of the tube furnace, and performing second heat treatment under nitrogen atmosphere in a manner of roasting for 2 hours at 400 ℃, cooling to room temperature, adding into water, stirring, washing for 10min, filtering and drying to obtain a fourth pre-product;

and carrying out third heat treatment on the fourth pre-product in an oxygen atmosphere at 800 ℃ for 3 hours in a roasting mode to obtain the niobium-phosphorus co-doped nickel-cobalt-manganese lithium aluminate quaternary material A2, wherein the chemical formula, the median particle diameter D50 and the element distribution are shown in Table 1.

Example 3

The niobium-phosphorus co-doped nickel cobalt manganese lithium aluminate quaternary material A3 is prepared by adopting the following method.

(1) Preparation of cobalt-aluminum hydrotalcite nano-sheet

Dissolving cobalt chloride calculated by Co element and aluminum chloride calculated by Al element in a molar ratio of 2:1 into deionized water to prepare a first solution with the total concentration of metal ions of 0.5 mol/L; an alkali solution having a sodium hydroxide concentration of 1.0mol/L and a sodium carbonate concentration of 0.5mol/L was prepared. Simultaneously adding the first solution and the alkali solution into a colloid mill with the rotating speed of 3000r/min according to the volume ratio of 1:1 for mixing reaction for 3min, stirring and aging the mixed suspension in a water bath with the temperature of 98 ℃ for 3h, repeatedly washing and filtering until the pH value of the filtrate is less than 7.5, drying the washed filter cake at the temperature of 120 ℃ for 10h to obtain cobalt-aluminum hydrotalcite nano-plates with the molar ratio of cobalt elements to aluminum elements of 2:1, wherein the chemical formula is Co ₄ Al ₂ (OH) ₁₂ CO ₃ ·6H ₂ O。

(2) Niobium element doping

According to Ni _0.8 Co _0.1 Mn _0.1 CO ₃ The precursor (the median particle diameter D50 is 10 mu m), the cobalt aluminum hydrotalcite nano-sheet prepared in the step (1) and the nano niobium pentoxide (the average particle diameter is 50 nm) are weighed as samples according to the molar ratio of 100:3:1, and the samples are subjected to first ball milling for 2.5 hours to obtain a first pre-product.

And respectively weighing the first pre-product and lithium nitrate (with average particle size of 6 mu m) according to the molar ratio of n (Ni+Co+Mn+Al+Nb) to n (Li) =1:1.04, performing second ball milling for 2.5h, then heating to 500 ℃ at a first heating rate of 8 ℃/min in an oxygen atmosphere, performing first roasting for 3h, continuously heating to 750 ℃ at a second heating rate of 5 ℃/min, performing second roasting for 15h, and cooling to room temperature to obtain the second pre-product.

(3) Doping of phosphorus element

Weighing the second pre-product and diammonium hydrogen phosphate (with the average particle size of 5 mu m) according to the molar ratio of 100:1, and performing third ball milling for 1.5 hours to obtain a third pre-product;

weighing a third pre-product and sodium hypophosphite according to the mol ratio of 5:1, placing sodium hypophosphite at the upstream of a tube furnace, placing the third pre-product at the downstream of the tube furnace, performing second heat treatment under nitrogen atmosphere in a manner of roasting for 3 hours at 300 ℃, cooling to room temperature, adding into water, stirring, washing for 10min, filtering and drying to obtain a fourth pre-product;

and carrying out third heat treatment on the fourth pre-product in an oxygen atmosphere at 700 ℃ for 4 hours to obtain the niobium-phosphorus co-doped nickel-cobalt-manganese lithium aluminate quaternary material A3, wherein the chemical formula, the median particle diameter D50 and the element distribution are shown in Table 1.

Example 4

The niobium-phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material A4 prepared by the method of example 1 is distinguished as follows:

in the step (1), cobalt sulfate is replaced by nickel sulfate to prepare nickel aluminum hydrotalcite Ni ₆ Al ₂ (OH) ₁₆ CO ₃ ·6H ₂ O; ni in the step (2) _0.8 Co _0.1 Mn _0.1 (OH) ₂ The molar ratio of the precursor to the nickel aluminum hydrotalcite nano-sheet to the nano niobium pentoxide is 100:1:0.5. Step (3) is the same as in example 1. The chemical formula and average particle size of quaternary material A4 are listed in table 1.

Example 5

Preparation of niobium doped lithium Nickel cobalt manganese aluminate Quaternary Material A5 by the method of example 3, with the difference Ni _0.8 Co _0.1 Mn _0.1 CO ₃ The molar ratio of the precursor to the cobalt-aluminum hydrotalcite nano-sheet prepared in the step (1) to the nano niobium pentoxide is 100:0.5:1. the chemical formula, median particle diameter D50 and element distribution of quaternary material A5 are listed in table 1.

Comparative example 1

The comparative example prepares a nickel cobalt lithium aluminate quaternary material D1 doped with no phosphorus element and doped with only niobium element.

Quaternary material D1 was prepared by the method of example 1, except that step (3) was not performed, and the chemical formula, median particle diameter D50, and element distribution of quaternary material D1 are listed in table 1.

The quaternary material D1 was subjected to scanning electron microscopy and the result is shown in fig. 2.

Comparative example 2

The comparative example prepares a lithium nickel cobalt aluminate quaternary material D2 doped with only phosphorus and without niobium.

The quaternary material D2 was prepared by the method of example 1, and steps (1) and (3) were the same as in example 1, except that in step (2), the material was prepared according to Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂ And (3) the precursor (the median particle diameter D50 is 9.5 mu m), the cobalt-aluminum hydrotalcite nano-sheet prepared in the step (1) is weighed as a sample according to the molar ratio of 100:1, and the sample is subjected to first ball milling for 2.5 hours to obtain a first pre-product. The chemical formula, median particle diameter D50 and element distribution of quaternary material D2 are listed in table 1.

The quaternary material D2 was subjected to scanning electron microscopy and the result is shown in fig. 3.

Comparative example 3

The comparative example prepares a nickel cobalt lithium aluminate quaternary material D3 doped with no niobium element and no phosphorus element.

(1) Preparation of cobalt-aluminum hydrotalcite nano-sheet

Dissolving cobalt sulfate calculated by Co element and aluminum sulfate calculated by Al element in a molar ratio of 3:1 into deionized water to prepare a first solution with total concentration of metal ions of 1.0 mol/L; an alkali solution having a sodium hydroxide concentration of 1.6mol/L and a sodium carbonate concentration of 0.25mol/L was prepared. Simultaneously adding the first solution and the alkali solution into a colloid mill with the rotating speed of 3000r/min according to the volume ratio of 1:1 for mixing reaction for 3min, stirring and aging the mixed suspension in a water bath with the temperature of 98 ℃ for 3h, repeatedly washing and filtering until the pH value of the filtrate is less than 7.5, drying the washed filter cake at the temperature of 120 ℃ for 10h to obtain cobalt-aluminum hydrotalcite nano-sheets with the cobalt-aluminum molar ratio of 3:1, wherein the chemical formula is Co ₆ Al ₂ (OH) ₁₆ CO ₃ ·6H ₂ O。

(2) Preparation of nickel cobalt manganese lithium aluminate quaternary material

According to Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂ The precursor (average grain diameter is 9.5 mu m) and the cobalt-aluminum hydrotalcite nano-sheet prepared in the step (1) are weighed as sampling products according to the proportion of 100:1, the precursor and the sampling products are mixed and solid-phase ball-milled for 2.5 hours, and the first ball milling is carried out for 2.5 hours, so that a pre-product is obtained.

And respectively weighing the pre-product and lithium hydroxide (with the average particle diameter of 7 mu m) according to the molar ratio of n (Ni+Co+Mn+Al) to n (Li) =1:1.06, performing second ball milling for 2.5 hours, then heating to 500 ℃ at a first heating rate of 2 ℃/min in an oxygen atmosphere, performing first roasting for 3 hours, continuously heating to 750 ℃ at a second heating rate of 2 ℃/min, performing second roasting for 15 hours, and cooling to room temperature to obtain the nickel cobalt manganese lithium aluminate quaternary material D3 without doping of niobium elements and phosphorus elements. The chemical formula, median particle diameter D50 and element distribution of quaternary material D3 are listed in table 1.

The quaternary material D3 was subjected to scanning electron microscopy and the result is shown in fig. 4.

Comparative example 4

The niobium-phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material D4 was prepared by the method of example 1, with the following differences:

and (3) replacing sodium hypophosphite in the step (3) with equimolar diammonium hydrogen phosphate, carrying out third ball milling on the second product and the diammonium hydrogen phosphate for 1.5 hours to obtain a third pre-product, and directly carrying out heat treatment to obtain the niobium-phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material D4, wherein the chemical formula, the median particle diameter D50 and the element distribution are shown in Table 1.

Comparative example 5

The method of example 1 was used to prepare a niobium phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material D5, with the following differences:

and (3) replacing the diammonium phosphate in the step (3) with equimolar sodium hypophosphite, placing the second pre-product in the downstream of the tube furnace, placing the diammonium phosphate in the upstream of the tube furnace, and performing second heat treatment under nitrogen atmosphere in a manner of roasting for 2 hours at the temperature of 300 ℃, cooling to the room temperature, adding into water, stirring, washing for 10 minutes, filtering and drying to obtain a fourth pre-product.

The chemical formula and the median particle diameter D50 of the obtained niobium-phosphorus co-doped nickel cobalt manganese lithium aluminate quaternary material D5 are shown in Table 1.

Comparative example 6

The comparative example adopts a conventional solid-phase coating method to prepare the niobium-phosphorus co-doped nickel cobalt manganese lithium aluminate quaternary material D6.

(1) Preparation of cobalt-aluminum hydrotalcite nano-sheet

Dissolving cobalt sulfate calculated by Co element and aluminum sulfate calculated by Al element in a molar ratio of 3:1 into deionized water to prepare a first solution with total concentration of metal ions of 1.0 mol/L; an alkali solution having a sodium hydroxide concentration of 1.6mol/L and a sodium carbonate concentration of 0.25mol/L was prepared. Simultaneously adding the first solution and the alkali solution into a colloid mill with the rotating speed of 3000r/min according to the volume ratio of 1:1 for mixing reaction for 3min, stirring and aging the mixed suspension in a water bath with the temperature of 98 ℃ for 3h, repeatedly washing and filtering until the pH value of the filtrate is lower than 7.5, drying the washed filter cake at the temperature of 120 ℃ for 10h to obtain cobalt-aluminum hydrotalcite nano-plates with the molar ratio of cobalt element to aluminum element of 3:1, wherein the chemical formula is Co ₆ Al ₂ (OH) ₁₆ CO ₃ ·6H ₂ O。

(2) Preparation of nickel cobalt manganese lithium aluminate quaternary material

According to Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂ The precursor (with the median particle diameter D50 of 9.5 mu m) and the cobalt-aluminum hydrotalcite nano-sheet prepared in the step (1) are weighed as sampling products according to the proportion of 100:1, the precursor and the cobalt-aluminum hydrotalcite nano-sheet are mixed and subjected to solid-phase ball milling for 2.5 hours, and the first ball milling is carried out for 2.5 hours, so that a pre-product is obtained.

And respectively weighing the pre-product and lithium hydroxide (with the average particle size of 7 mu m) according to the molar ratio of n (Ni+Co+Mn+Al+Nb) to n (Li) =1:1.06, performing second ball milling for 2.5 hours, then heating to 500 ℃ at a first heating rate of 2 ℃/min in an oxygen atmosphere, performing first roasting for 3 hours, continuously heating to 750 ℃ at a second heating rate of 2 ℃/min, performing second roasting for 15 hours, and cooling to room temperature to obtain the nickel cobalt manganese lithium aluminate anode material.

(3) Doping of niobium element

And (3) weighing the nickel cobalt manganese lithium aluminate anode material and the nano niobium pentoxide in the step (2) according to the molar ratio of 100:0.5, performing solid-phase ball milling for 2.5h, and roasting for 5h at 750 ℃ in an oxygen atmosphere to obtain the niobium-doped nickel cobalt manganese lithium aluminate anode material.

(4) Doping of phosphorus element

The phosphorus doping step was the same as step (3) of example 1, and the chemical formula, median particle diameter D50, and element distribution of the quaternary material D6 are shown in table 1.

Comparative example 7

The niobium-phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material D7 is prepared by adopting the method of the embodiment 1, wherein the adopted aluminum-based hydrotalcite is magnesium aluminum hydrotalcite Mg ₄ Al ₂ (OH) ₁₂ CO ₃ ·6H ₂ O, its chemical formula, median particle diameter D50 and element distribution are listed in Table 1.

Test examples 1 to 12

The quaternary materials of examples 1-5 and comparative examples 1-7 are used as positive electrode materials, respectively mixed with acetylene black conductive agent and polyvinylidene fluoride binder according to the mass ratio of 94:3:3, coated on the surface of an aluminum foil current collector, dried at 110 ℃ and pressed into tablets, electrode plates with the diameter of 1cm are manufactured by a punching machine, vacuum dried in a vacuum oven at 120 ℃ for 24 hours are used as positive electrodes, lithium metal plates are used as negative electrodes, a polyethylene film is used as a diaphragm, and 1mol/L LiPF is used ₆ And/(ethylene carbonate+dimethyl carbonate) is an electrolyte, wherein the volume ratio of ethylene carbonate to dimethyl carbonate is 1:1, and the button cell is assembled in a glove box.

Electrochemical performance test is carried out by adopting a Wuhan blue electric CT2001A battery tester, and the charge-discharge voltage range is 2.7-4.3V (vs. Li) ⁺ /Li). After 0.1C is charged and discharged for 5 cycles, 0.2C is charged and discharged for 3 cycles, and finally 0.5C is subjected to long-period cycle. The results are shown in Table 1.

TABLE 1

According to the data in table 1, niobium elements in the niobium-phosphorus co-doped nickel cobalt manganese lithium aluminate quaternary materials A1-A5 prepared by the method disclosed by the invention are uniformly distributed in a material bulk phase, and phosphorus elements are mainly concentrated on the surface of the material. Compared with the D1 doped with niobium and the D2 doped with phosphorus, the capacity retention rates of D1 and D2 in 200 times are lower than those of A1-A5 doped with niobium and phosphorus, but higher than those of D3 undoped with niobium and phosphorus, which shows that the niobium and phosphorus co-doping can further improve the cycle stability of the quaternary material and has positive effects on the improvement of the capacity retention rate. In example A5, the ratio of cobalt element in cobalt-aluminum hydrotalcite to niobium element in niobium pentoxide was as followsFor example, the ratio of cobalt element to niobium element is 1:1, and cobalt element is insufficient to drive equimolar niobium element to carry out synergistic diffusion during solid phase reaction, so that part of niobium in A5 is still enriched on the surface of the material, effective uniform doping is not realized, and the capacity retention rate is obviously lower than that of A1-A4. In the method, the phosphorus doping adopts two modes of solid-phase diffusion and vapor deposition to carry out phosphorus doping, so that the phosphorus doping effect and the surface phosphorus enrichment effect in the bulk phase of the material are both improved, and the ratio A of the phosphorus content in the surface and the bulk phase is compared with the doping modes of only solid-phase diffusion and only vapor deposition of D4 and D5 _P /D _P The capacity retention rate is obviously lower than that of A1-A5 due to lower or higher content, which indicates that the multiple phosphorus doping modes cooperate, and the cycle performance of the material can be further improved. The niobium element in D6 is enriched on the surface of the material particles, which proves that the uniform doping of the large-ion-diameter element is difficult to realize after the quaternary material structure is formed, and the first discharge capacity is obviously lower than that of the embodiment of uniform doping although the first discharge capacity is not obviously changed. For the quaternary material D7, the magnesium-aluminum hydrotalcite nano-sheet without transition metal is used for preparing the quaternary material, and niobium element is enriched on the surface of material particles, so that the transition metal in the aluminum-based hydrotalcite nano-sheet can drive the niobium element into the material, the niobium element in the prepared material is uniformly distributed, and further, higher first discharge capacity and good long-period cycle performance are obtained. Meanwhile, the method disclosed by the invention can flexibly control the proportion of four elements in the material by changing the types of the aluminum-based hydrotalcite nano-sheets and the proportion of metal elements, thereby meeting the requirement of improving the electrical property of the material.

The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, but the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solutions of the present disclosure within the scope of the technical concept of the present disclosure, and all the simple modifications belong to the protection scope of the present disclosure.

In addition, the specific features described in the above embodiments may be combined in any suitable manner without contradiction. The various possible combinations are not described further in this disclosure in order to avoid unnecessary repetition.

Moreover, any combination between the various embodiments of the present disclosure is possible as long as it does not depart from the spirit of the present disclosure, which should also be construed as the disclosure of the present disclosure.

Claims (14)

1. The niobium-phosphorus co-doped nickel-cobalt-manganese lithium aluminate quaternary material is characterized by comprising a chemical formula of LiNi _x Co _y Mn _z Al _w Nb _n P _m O ₂ X+y+z+w+n+m=1, y is 0 < 0.2, z is 0 < 0.1, w is 0 < 0.05,0.002 < n is 0.02,0.001 < m is 0.02;

wherein A is _Nb And D _Nb Has a ratio of 0.9 to 1.1, A _P And D _P The ratio of (2) is 5-15;

a is based on the total mole of nickel element, cobalt element, manganese element, aluminum element, niobium element and phosphorus element on the surface of the particle _Nb Representing the molar ratio of niobium element on the surface of the particles, A _P A molar ratio of phosphorus element representing the surface of the particles;

d based on the total mole of nickel element, cobalt element, manganese element, aluminum element, niobium element and phosphorus element in the particle body phase _Nb Represents the molar ratio of niobium element in the bulk phase of the particles, D _P Representing the molar ratio of phosphorus element in the bulk phase of the particles.

2. The niobium phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material according to claim 1, wherein the particles have a median particle diameter D50 of 8-12 μιη.

3. A method for preparing the niobium-phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material according to claim 1 or 2, characterized in that the method comprises the following steps:

(1) Carrying out first ball milling on the aluminum-based hydrotalcite nano-sheet, the nickel-cobalt-manganese ternary precursor and the niobium-containing compound to obtain a first pre-product;

(2) Performing second ball milling on the first pre-product and a lithium-containing compound, and performing first heat treatment under a first oxygen-containing atmosphere to obtain a second pre-product;

(3) Performing third ball milling on the second pre-product and the first phosphorus-containing compound;

(4) Carrying out second heat treatment on the third pre-product obtained in the step (3) and a second phosphorus-containing compound in an inert atmosphere;

(5) Carrying out third heat treatment on the fourth pre-product obtained in the step (4) in a second oxygen-containing atmosphere;

wherein the aluminum-based hydrotalcite nano-sheet comprises transition metal, the transition metal is cobalt element or nickel element, and the mol ratio of the transition metal element to the aluminum element is (2-5): 1.

4. The method according to claim 3, wherein in the step (1), a molar ratio of the transition element in the aluminum-based hydrotalcite nanoplatelets to the niobium element in the niobium-containing compound is 2:1 or more.

5. The method of claim 3, wherein the nickel cobalt manganese ternary precursor has the formula Ni _1-a-b Co _a Mn _b (OH) ₂ Or Ni _1-a-b Co _a Mn _b CO ₃ Wherein a is more than 0 and less than or equal to 0.1, b is more than 0 and less than or equal to 0.1;

optionally, the median particle diameter D50 of the nickel-cobalt-manganese ternary precursor is 8-12 μm.

6. The method of claim 3, wherein the niobium-containing compound comprises one or more of niobium pentoxide, niobium oxalate, and ammonium niobium oxalate;

the lithium-containing compound comprises one or more of lithium hydroxide, lithium carbonate and lithium nitrate;

the first phosphorus-containing compound comprises one or more of ammonium phosphate, diammonium phosphate and monoammonium phosphate;

the second phosphorus-containing compound comprises phosphite and/or hypophosphite;

optionally, the phosphite comprises sodium phosphite and/or ammonium phosphite;

the hypophosphite comprises sodium hypophosphite and/or ammonium hypophosphite;

optionally, the molar ratio of the first phosphorus-containing compound to the second pre-product is (0.5-4): 100;

the molar ratio of the second phosphorus-containing compound to the third pre-product is 1: (2-50).

7. A method according to claim 3, wherein the niobium-containing compound has an average particle size of 50-80nm; the average particle diameter of the lithium-containing compound is 6-8 mu m; the first phosphorus-containing compound has an average particle diameter of 5-10 μm.

8. A method according to claim 3, wherein the molar ratio of the total molar sum of nickel element, cobalt element, manganese element, aluminum element and niobium element in the first pre-product to lithium element in the lithium-containing compound is 1 (1.0-1.1).

9. A method according to claim 3, wherein in step (2), the first heat treatment comprises the steps of:

a. heating to 500-600 ℃ at a first heating rate of 1-8 ℃/min, and performing first roasting for 1-3h;

b. continuously heating to 700-800 ℃ at a second heating rate of 2-6 ℃/min, and performing second roasting for 10-15h.

10. A method according to claim 3, wherein the first ball milling is for a period of 1-4 hours; the second ball milling time is 1-4h, and the third ball milling time is 1-4h.

11. A process according to claim 3, wherein step (4) is carried out in a tube furnace, the second phosphorus-containing compound being placed upstream of the tube furnace, and the third pre-product being placed downstream of the tube furnace.

12. A method according to claim 3, wherein in step (4), the method of the second heat treatment is firing, and the conditions of the second heat treatment include: the temperature is 200-400 ℃ and the time is 3-8h;

in the step (5), the third heat treatment method is roasting, and the third heat treatment conditions include: the temperature is 600-850 ℃ and the time is 3-8h.

13. A method according to claim 3, wherein the inert atmosphere comprises nitrogen and/or argon;

the first oxygen-containing atmosphere and the second oxygen-containing atmosphere are the same or different, and are each independently an oxygen atmosphere and/or an air atmosphere.

14. A lithium ion battery comprising a positive electrode, an electrolyte and a negative electrode, wherein the positive electrode comprises the niobium-phosphorus co-doped lithium nickel cobalt manganese aluminate quaternary material of claim 1 or 2.

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