CN107565127B

CN107565127B - Preparation method of nitrogen-doped nickel-cobalt-manganese ternary material

Info

Publication number: CN107565127B
Application number: CN201710773256.XA
Authority: CN
Inventors: 童庆松; 余欣瑞; 陈方园; 张晓红; 翁景峥; 朱德青; 郑思宁
Original assignee: Fujian Normal University
Current assignee: Fujian Normal University
Priority date: 2017-08-31
Filing date: 2017-08-31
Publication date: 2020-09-22
Anticipated expiration: 2037-08-31
Also published as: CN107565127A

Abstract

The invention relates to a preparation method of a nitrogen-doped nickel-cobalt-manganese ternary material. The method comprises the steps of mixing a mixture of nickel, cobalt and manganese compounds with deionized water and a nitrogen dopant, and preparing a dried precursor through the steps of adding ammonia water, adding a lithium compound, wet grinding, aging, drying and the like. And (3) placing the dried precursor in oxygen-enriched air or pure oxygen atmosphere, and preparing the nitrogen-doped nickel-cobalt-manganese ternary material by adopting a programmed heating method. The nitrogen dopant is hydrazine, hydrazine hydrate, hydrochloride of the hydrazine hydrate, nitrate of the hydrazine hydrate, diethylenetriamine, melamine, urea, acetonitrile or ethylenediamine. The method has the advantages of low raw material cost, wide raw material source, simple preparation process, simple and convenient operation, less time consumption, and no LiMn in the prepared sample₆The prepared electrode material has good consistency, uniform composition and excellent discharge performance, particularly has good discharge cycle performance under the condition of large current, and lays a good foundation for industrialization.

Description

Preparation method of nitrogen-doped nickel-cobalt-manganese ternary material

Technical Field

The invention belongs to the technical field of preparation of battery electrode materials, and relates to a preparation method of a nitrogen-doped nickel-cobalt-manganese ternary material which can be used for lithium batteries, lithium ion batteries, polymer batteries and super capacitors.

Technical Field

With the increasing exhaustion of fossil energy, energy problems become a focus of attention. The search for new energy storage materials becomes one of the hot spots of research. The lithium ion battery of the new energy storage system has the advantages of high voltage, large capacity, no memory effect, long service life and the like, and can be widely applied to digital products such as mobile phones, digital cameras, notebook computers and the like and power tools such as electric vehicles, hybrid electric vehicles and the like.

The lithium ion battery comprises a positive electrode material, a negative electrode material, a diaphragm, electrolyte, a current collector and the like. Among them, the positive electrode material largely determines the performance of the battery. The positive electrode materials that have been successfully commercialized include lithium cobaltate, lithium manganate, lithium iron phosphate, and the like. However, the above materials have many disadvantages, and it is a hot research to find a positive electrode material with higher cost performance. In 1997, Ohzuku et al [ Ohzuku t.et al, chem.lett., 1997, 68: 642.]LiNi was first studied_1/3Mn_1/3Co_1/3O₂The properties of type III ternary materials. Research shows that the material fuses LiCoO₂、LiNiO₂And LiMn₂O₄Has the advantages of high reversible capacity, low cost, low toxicity and the like. The nickel cobalt manganese ternary material can be represented as: LiNi_xCo_yMn_zO₂For example, the ternary material with the molar ratio of nickel, cobalt and manganese (x: y: z) of 3: 3 is called 333 type for short, the ternary material with the molar ratio of nickel, cobalt and manganese of 5: 2: 3 is called 523 type, the ternary material with the molar ratio of nickel, cobalt and manganese of 8:1 is called 811 type, and other similar types are used, the 333 type, 523 type, 622 type and 811 type ternary materials all have α -NaFeO₂A layer-shaped structure. In the ternary material, the valence of nickel, cobalt and manganese elements is +2 valence, +3 valence and +4 valence respectively. Ni is the main active element. Theoretically, the higher the relative content of nickel, the higher the discharge capacity of the ternary material.

Koymaya et al [ Koymaya y., et al, j.power Sources, 2003, 119 (2): 644-648.]It is considered that Li_1-xNi_1/3Co_1/3Mn_1/3O₂Charging process with LiNi_1/3Co_1/3Mn_1/3O₂The examples are: with the elimination of Li ions, different electron pairs react. When 0 < x < 1/3, Ni occurs²⁺/Ni³⁺A transition of (a); when 1/3 < x < 2/3, Ni occurs³⁺/Ni⁴⁺A transition of (a); when 2/3 < x < 1, Co occurs³⁺/Co⁴⁺Is performed.

When 0 < x < 1/3

When 1/3 < x < 2/3

When 2/3 < x < 1:

for ternary materials, Ni at charging voltages below 4.3V (vs Li/Li +)²⁺As the main active material, Co³ ⁺Can improve the cyclability and rate capability of the material, while Mn⁴⁺Does not participate in the oxidation-reduction reaction in the circulation process.

Due to xLi₂MnO₃·(1-x)LiMO₂The structure and chemical composition of solid solution (M ═ Ni, Co, Mn) materials are very close to those of ternary materials, and many documents incorrectly express the structures of the two materials. For xLi₂MnO₃·(1-x)LiMO₂Solid solution (M ═ Ni, Co, Mn), charge voltage<4.4V, Li in solid solution₂MnO₃No electrochemical activity [ Yang f., Zhang q.et al, electrochim. acta, 2015, 165: 182-190.]. At this voltage, the LiMO in solid solution is mainly involved in the electrochemical reaction during charging₂。Li⁺From LiMO₂Is removed while M is oxidized to MO₂. During discharge in this case, with Li⁺Embedding, MO₂Can not be completely converted into LiMO₂Resulting in a partially irreversible reaction. When charging voltage>Li in solid solution at 4.4V₂MnO₃2 Li being extractable⁺And O^2-Incorporation (actually taking off Li)₂O), producing electrochemically active MnO₂Phase (1); during discharge, part of Li originally extracted⁺Can be embedded back into MnO₂In (1). [ Chen C.J., et al., J.am.).Chem.Soc.，2016，138：8824-8833.]It can be seen from the above discussion that while both ternary and solid solution materials have the layered α -NaFeO₂The structure and chemical composition are very similar. However, the charge-discharge curves and XRD diffraction patterns of the ternary material and the solid solution material are obviously different. From the relation curve of the discharge voltage and the discharge capacity of charge and discharge, when the charge voltage is higher than 4.4V, the charge specific capacity and the discharge specific capacity of the solid solution are obviously increased, and the discharge curve of the solid solution has the characteristic of oblique lines and has no obvious discharge voltage platform; in this case, the charging specific capacity and the discharging specific capacity of the ternary material are only slightly increased and are not obviously increased, and the discharging curve of the ternary material presents an S-shaped characteristic and has an obvious discharging voltage platform.

In recent years, spray drying and other preparation methods are also concerned, however, the coprecipitation method is still the main method for preparing the nickel, cobalt and manganese ternary material. Other methods are not industrially valuable. Briefly discussed below.

The coprecipitation method is to add a precipitator and a complexing agent into a mixed solution of various cations to control the nucleation and growth processes of precipitation, so as to obtain coprecipitation with controllable morphology and particle size. And filtering and drying the prepared coprecipitation to obtain a precursor. The precursor is mixed with lithium salt and then is sintered at high temperature to prepare the anode material. The synthesis method has good reproducibility, and the prepared product has uniform composition. The coprecipitation with controllable appearance and particle size can be prepared by controlling the stirring speed, pH value, aging temperature, precipitator, the dripping speed of the precipitator, the proportion of ammonia water and metal ions and the like in the precipitation process, and the problems of uneven material mixing, too wide particle size distribution and the like in the solid-phase synthesis method are solved. The coprecipitation method is classified into a hydroxide and carbonate coprecipitation method. Specifically, hydroxide and carbonate precipitating agents are respectively used for forming precursor precipitates of transition metal ions, then the precursor precipitates are mixed with lithium salt, and finally the ternary material is prepared by sintering. The hydroxide coprecipitation method is a common method for synthesizing ternary material precursors. The method generally uses NaOH as a precipitator and ammonia water as a complexing agent, controls the pH value in the reaction process through the precipitator, and realizes the control of the particle size of a precursor through controlling the reaction temperature and the stirring speedAnd the purpose of the morphology, and finally the morphology and the electrochemical performance of the ternary material are controlled. During the preparation, due to the intermediate product Mn (OH) formed₂The precursor is unstable and is easily oxidized by air, and the performance of the material is affected, so nitrogen needs to be introduced for protection in the process of preparing the precursor. The hydroxide coprecipitation method has the advantages that a precursor with uniform particle size distribution is obtained by controlling reaction conditions; the disadvantage is the complex preparation process. In the preparation process, the concentration of raw materials, the dropping speed, the stirring speed, the pH value and the reaction temperature all influence the tap density and the particle size uniformity of the material. The biggest problems with this approach are: the precipitation conditions of hydroxide coprecipitation generated by nickel, cobalt and manganese are greatly different, and if the dosage of alkali in the precipitation process is insufficient, nickel and cobalt ions may be incompletely precipitated; if the amount of the alkali used in the precipitation process is excessive, the precipitated manganese ions may be dissolved, so that the room-temperature chemical composition and the performance of the prepared sample are difficult to be consistent.

Liang et al [ Liang L, et al, Electrochim Acta, 2014, 130: 82-89.]With NiSO₄·6H₂O、CoSO₄·7H₂O and MnSO₄·H₂Taking O as a raw material and 0.6mol/L ammonia water as a complexing agent, and preparing a uniformly mixed spherical precursor at a stirring speed of 800r/min and a pH value of 11.2. Washing, filtering, drying and calcining the precursor to obtain the product with the tap density of 2.59g/cm³622 type material. Under the current of 1C multiplying power and the voltage range of 2.8-4.3V, the discharge specific capacity of the prepared sample at the 1 st cycle is 172.1 mAh.g^-1The capacity retention rates at 100 cycles were 94.3%, respectively. Wen Lei et al [ Wen Lei, et al, Beijing university school newspaper, 2006, 42 (1): 12-17.]With LiOH. H₂O、NaHCO₃、CoSO₄·7H₂O、NiSO₄·6H₂O and MnSO₄·5H₂O is used as a raw material, carbonate precursor precipitate is prepared, and LiNi is prepared by washing, filtering, drying and secondary sintering_1/3Mn_1/3Co_1/3O₂And (3) sampling. Research shows that in a voltage range of 2.5-4.4V, the first discharge capacity of the prepared sample is 162 mAh.g^-1Has good cyclicityCan be used.

Mao yu qin, etc. (Mao yu qin, Chinese patent: CN 103972499A, 2014-08-06]Firstly, preparing soluble nickel salt, cobalt salt, aluminum salt and lithium salt into spherical LiNi by a coprecipitation method_1-a-bCo_aAl_bO₂Mixing the material with nano TiO₂Spraying the powder into a coating device to obtain LiNi_1-a-bCo_aAl_bO₂/TiO₂Capacity retention of greater than 99% at 50 cycles.

Previous researches show that the concentration of raw materials, the dropping speed of a precipitator, the stirring speed, the pH value and the reaction temperature are the key points for preparing the ternary material with high tap density and uniform particle size distribution. Zhou new east et al [ zhou new east et al, chinese patent: CN102244239A, 2011-11]The spherical nickel-cobalt-aluminum ternary material is prepared by using a nickel, cobalt and aluminum salt solution and a lithium source through a secondary precipitation method, and the prepared sample has high tap density (3.02 g/cm)³) And the like. Further studies have shown that, in addition to the composition, particle size and particle size distribution of particles prepared by co-precipitation having an effect on the properties of the prepared samples, the radial distribution of the sample particle composition also has a significant effect on the properties of the samples. Hua et al [ Hua C, et al, j. alloys and Compounds, 2014, 614: 264-270.]With NiSO₄·6H₂O、CoSO₄·7H₂O、MnSO₄·5H₂Dissolving O as raw material in a circulating stirring kettle, adding ammonia water as complexing agent, and adding sodium hydroxide solution to adjust pH to 11.5. Stirring the mixture for 24 hours at the rotating speed of 750rpm and at the temperature of 55 ℃ to prepare a hydroxide precursor. And filtering, washing and drying the prepared precursor, and mixing and calcining the precursor and lithium hydroxide to prepare the 811 type ternary material with linear gradient. Studies show that the nickel content gradually decreases and the manganese content gradually increases from the core to the surface of the sample particles. Under the condition of large multiplying current, the discharge capacity and the cycle performance of the 811 type ternary material with the composition gradient distribution are obviously superior to those of the corresponding material with the uniform composition distribution. The discharge capacity of the 811 type ternary material forming the linear gradient distribution in the 1 st cycle is 185.2 mAh.g in a voltage interval of 2.8-4.3 and under a current of 1C multiplying power^-1The capacity retention at 100 cycles was 93.2%.

Hou et al, j.power Sources, 2014, 265: 174-181 ] sample preparation by fractional precipitation: pumping reactant solution with the molar ratio of nickel, cobalt and manganese of 8:1 into a reaction kettle to form 811 nuclei, and pumping reactant solution with the molar ratio of nickel, cobalt and manganese of 3: 3 to form a first shell layer; then pumping reactant solution with the molar ratio of nickel, cobalt and manganese being 4: 2 to form a second shell layer; finally, the ternary material with a core of 811 type and a shell of 333 type and 422 type is prepared. The capacity retention for the 300 cycles of the prepared sample at 4C rate current was 90.9%.

Guokai et al [ guokai et al, chinese patent: CN 104979553A, 2015-10-14]Soluble nickel salt, cobalt salt, aluminum salt, lithium carbonate or lithium hydroxide are prepared into LiNi by a coprecipitation method_cCo_1-c-dAl_dO₂(c is more than 0.5, 0.5 is more than d is more than 0, 1 is more than c + d) coated LiNi_aCo_1-a-bAl_bO₂(a is more than 0.7, b is more than or equal to 0.05 and more than or equal to 0, and a + b is more than 1). Research shows that the coated micron LiNi_aCo_1-a-bAl_bO₂The cycle stability and the thermal stability of (a is more than 0.7, b is more than or equal to 0 and more than 1 and more than a + b) are obviously improved, and the flatulence rate is obviously reduced. Micron LiNi_0.8Co_0.15Al_0.05O₂Has a tap density of 2.51g/cm³. Under the voltage range of 3.0-4.3V and the current with 0.1C multiplying power, the first discharge capacity of the sample is 194.5mAh/g, and the first charge-discharge efficiency is 91.9%.

However, despite the above improvements, the ternary materials prepared at present have problems such as low electronic conductivity, poor high rate stability, poor high voltage cycling stability, cation shuffling, poor high and low temperature performance, and the like. In response to the above problems, the performance is currently improved mainly by doping, surface coating and post-treatment. However, the actual improvement effect is not significant at present.

Disclosure of Invention

The coprecipitation method is to add a precipitant into a solution of mixed metal salts to precipitate two or more cations in the solution together to produce a precipitate mixture or a pure solid solution precursor. The sample prepared by the coprecipitation method has the advantages of narrow particle size distribution, high tap density, excellent electrochemical performance and the like. However, the coprecipitation method requires energy-consuming and water-consuming preparation steps such as filtration and washing, and generates a large amount of industrial wastewater. In the preparation process of the coprecipitation method, the added precipitant is difficult to form uniform concentration in each part of the mixed solution, so that precipitated particles are agglomerated or form nonuniform composition. In addition, the precipitation concentration products of nickel, cobalt and manganese salts have large difference, and the precipitation conditions of different ions have large difference. Manganese ions are easy to over-dissolve in a strong alkaline solution, the stoichiometric ratio of precursors is difficult to control, and the electrochemical properties of samples in different batches are affected. In order to improve the preparation process conditions and reduce the defects of the preparation method, the invention adopts a direct precipitation method to prepare the nickel-cobalt-manganese ternary material. In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:

respectively weighing a nickel compound, a cobalt compound, a manganese compound, a lithium compound and a nitrogen dopant according to the molar ratio x, y, z, k and m of nickel, cobalt, manganese, lithium and nitrogen ions; mixing a nickel compound, a cobalt compound and a manganese compound to obtain a mixture 1, and adding deionized water with the volume 1-50 times of the total volume of the mixture 1; adding a nitrogen doping agent under the condition of continuous stirring, and uniformly mixing; dropwise adding ammonia water under the condition of continuous stirring until the acidity of the solution falls within the range of pH 10.0-13.5, adding the weighed lithium compound, and uniformly mixing by using mixing equipment; aging for 5-48 hours at any temperature within a temperature range of 50-90 ℃ in an inert atmosphere of nitrogen, argon or helium without oxygen to prepare a precursor 2; heating the precursor 2 at any temperature within a range of 120-220 ℃ under a vacuum condition with the pressure lower than 1 atmospheric pressure to prepare a dried precursor 3 or preparing the dried precursor 3 at any temperature within a range of 120-220 ℃ by adopting a spray drying method; and (3) placing the dried precursor 3 in oxygen-enriched air or oxygen atmosphere, and preparing the nitrogen-doped nickel-cobalt-manganese ternary cathode material by adopting a programmed heating method.

Two or more compounds of the weighed nickel compound, cobalt compound, manganese compound and lithium compound are soluble in water.

The molar ratio x, y, z, k and m of the nickel ions, the cobalt ions, the manganese ions, the lithium ions and the nitrogen ions satisfy the following relation:

x, y, z, m is (0.48-0.52), (0.18-0.20), (0.27-0.30), (0.001-0.03), k is more than or equal to 0.95 and less than or equal to 1.05, and x + y + z + m is 1;

or x, y, z, m is (0.58-0.62), (0.18-0.20), (0.17-0.20), (0.001-0.03), k is more than or equal to 0.95 and less than or equal to 1.05, and x + y + z + m is 1;

or x, y, z, m (0.78-0.82), m (0.08-0.10), 0.08-0.10, 0.001-0.03, k is more than or equal to 0.95 and less than or equal to 1.05, and x + y + z + m is more than or equal to 1.

The nitrogen dopant is hydrazine, hydrazine hydrate, hydrochloride of the hydrazine hydrate, nitrate of the hydrazine hydrate, diethylenetriamine, melamine, urea, acetonitrile or ethylenediamine.

The ternary material simultaneously satisfies the following characteristics that diffraction peaks on an XRD diffraction pattern and layered α -NaFeO₂The characteristic diffraction peaks of the structure (JCPDS card 09-0063) are matched; under the conditions of 0.2C multiplying current and 1 st charge-discharge cycle, the proportion of increasing the charging specific capacity by 4.6V to 4.4V is less than 25 percent relative to the constant current charging of a lithium electrode; li which does not correspond to JCPDS card 27-1252 in the range of 20-25 degrees of 2 theta angle of sample XRD diffraction pattern₂MnO₃The diffraction peak of (1).

The programmed heating method is carried out by placing the dried precursor 3 in oxygen-enriched air or oxygen atmosphere, carrying out programmed heating from room temperature to any temperature in the temperature range of 780-930 ℃ at the speed of 0.1-5 ℃/min, and cooling to room temperature to obtain the nitrogen-doped nickel-cobalt-manganese ternary cathode material.

The nickel compound is nickel hydroxide, nickel oxide, nickel nitrate, nickel chloride, nickel oxalate, basic nickel carbonate, nickel acetate or nickel carbonate.

The cobalt compound is cobalt hydroxide, cobalt oxide, cobalt oxalate, cobalt nitrate, cobalt chloride, basic cobalt carbonate, cobalt acetate or cobalt carbonate.

The manganese compound is manganese hydroxide, manganese oxide, manganese nitrate, manganese oxalate, manganese carbonate, manganese chloride or manganese acetate.

The lithium compound is lithium oxide, lithium nitrate, lithium chloride, lithium carbonate, lithium acetate or lithium hydroxide.

The oxygen-enriched air is air with the oxygen volume content of 30-99%.

The spray drying method is drying at any temperature within the temperature range of 120-220 ℃.

The mixing equipment is ball milling or sanding equipment.

The invention has the advantages of low cost of raw materials, wide raw material sources, simple preparation process, simple and convenient operation and less time consumption. Compared with a coprecipitation method, the sewage discharged in the preparation process is obviously reduced, and LiMn does not exist in the prepared sample₆The superlattice structure increases the specific charge capacity by less than 25% compared with 4.4V when the lithium electrode is charged to 4.6V by constant current, the prepared electrode material has good consistency, uniform composition and excellent discharge performance, particularly has good discharge cycle performance under the condition of large current, and lays a good foundation for industrialization.

Compared with the invention patent (zl201210391584.0,201210391629.4,201210391413.8,201210391672.0,201210391441.x) related to solid solution preparation, which was previously applied by this project group, the invention patent is a patent with a completely different composition. From a structural point of view, the samples prepared herein do not have LiMn₆Superlattice structure, and the structure of the solid solution sample has LiMn₆A superlattice structure; from the chemical composition of the sample, the compositions of the 523, 622, 811 type ternary materials are close to Li [ Ni ]_0.5Co_0.2Mn_0.3]O₂、Li[Ni_0.6Co_0.2Mn_0.2]O₂、Li[Ni_0.8Co_0.1Mn_0.1]O₂(ii) a And solid solution xLi₂MnO₃(1-x)Li[Ni_yMn_zCo_k]O₂Has the chemical formula of Li_(1+x)[Ni_(1-x)yCo_(1-x)kMn_(x+z-xz)]O_(2+x). If the formula xLi in patent ZL201210391584.0 is considered₂MnO₃(1-x)Li[Ni_yMn_zCo_k]O₂The value range of (a) can be calculated to obtain the theoretical composition of a solid solution sample: li: ni: co: mn: the O molar ratio is (1-1.39): (0.0173-0.333): (0.0174-0.443): (0.204-0.952): (1.87-2.26). The theoretical composition of the solid solution patent applied in the previous period of this project group is similar to that of patent ZL201210391584.0, therefore, the chemical formulas of the solid solution patent applied in the previous period and the solid solution applied in the previous period have certain similarities, but the two are completely different inventions.

Drawings

Figure 1 is an XRD diffractogram of a sample prepared in example 1 of the present invention.

FIG. 2 is a discharge curve diagram of the 1 st cycle at a current of 1C rate in a voltage range of 2.5 to 4.3V for the sample prepared in example 1 of the present invention.

FIG. 3 is a graph showing the discharge capacity versus cycle performance of the sample prepared in example 1 of the present invention at a voltage range of 2.5 to 4.3V and a current of 1C rate.

Detailed Description

The present invention will be further described with reference to the following examples. The examples are merely further additions and illustrations of the present invention, and are not intended to limit the invention.

Example 1

Respectively weighing nickel acetate, cobalt acetate, manganese carbonate, lithium hydroxide and hydrazine hydrate according to the molar ratio of nickel, cobalt, manganese, lithium and doped nitrogen ions of 0.5:0.20:0.29:1:0.01, mixing the nickel acetate, the cobalt acetate and the manganese carbonate to obtain a mixture 1, adding deionized water with the volume being 3 times of the total volume of the mixture 1, uniformly mixing, adding hydrazine hydrate under the condition of continuous stirring, uniformly mixing, dropwise adding ammonia water under the condition of continuous stirring until the acidity of the solution is pH 12.5, adding the weighed lithium hydroxide, uniformly mixing by using ball milling equipment, aging for 24 hours under the nitrogen atmosphere and 85 ℃ to obtain a precursor 2, heating the precursor 2 under the vacuum condition of 0.1 atmospheric pressure at 220 ℃ to obtain a dried precursor 3, placing the precursor 3 in oxygen-enriched air with the volume content of 90% of oxygen, heating from room temperature to 920 ℃ at the speed of 5 ℃/min, cooling to room temperature to obtain the NaFeO with the content of α -NaFeO₂The nitrogen-doped nickel-cobalt-manganese ternary cathode material has a structure.

The ternary material simultaneously satisfies the following characteristics that diffraction peaks on an XRD diffraction pattern are allLayered α -NaFeO with JCPDS card 09-0063₂The characteristic diffraction peaks of the structure are matched; under the conditions of 0.2C multiplying current and 1 st cycle charge and discharge, the proportion of increasing the specific charge capacity by 16 percent relative to the constant current charge of a lithium electrode to 4.6V to 4.4V is increased; no weak diffraction peak appears in the range of 20-25 degrees of 2 theta angle of XRD diffraction pattern of the sample, and no Li corresponding to JCPDS card 27-1252₂MnO₃Diffraction peaks resulting from diffraction.

Example 2

Respectively weighing nickel acetate, cobalt nitrate, manganese carbonate, lithium carbonate and hydrazine hydrate according to the molar ratio of nickel, cobalt, manganese, lithium and doped nitrogen ions of 0.52:0.18:0.299:1:0.001, mixing the nickel acetate, the cobalt nitrate and the manganese carbonate to obtain a mixture 1, adding deionized water with the volume 50 times of the total volume of the mixture 1, uniformly mixing, adding hydrazine hydrate under the condition of continuous stirring, uniformly mixing, dropwise adding ammonia water under the condition of continuous stirring until the acidity of the solution is pH 13.5, adding weighed lithium carbonate, uniformly mixing by using a ball milling device, aging for 48 hours under the nitrogen atmosphere and the temperature of 90 ℃ to obtain a precursor 2, heating the precursor 2 under the vacuum condition of 0.1 atmospheric pressure at the temperature of 210 ℃ to obtain a dried precursor 3, placing the precursor 3 in oxygen-enriched air with the volume content of 99% of oxygen, heating from the room temperature to 930 ℃ at the speed of 1 ℃/min, cooling to the room temperature to obtain the layered α -NaFeO₂The nitrogen-doped nickel-cobalt-manganese ternary cathode material has a structure.

The ternary material simultaneously meets the following characteristics that diffraction peaks on an XRD diffraction pattern are all equal to those of layered α -NaFeO of JCPDS card 09-0063₂The characteristic diffraction peaks of the structure are matched; the button half-cell prepared from the prepared ternary material is charged to 4.6V to 4.4V at a constant current relative to a lithium electrode under the conditions of 0.2C rate current and 1 st cycle charge and discharge, and the ratio of the increase of the specific charge capacity is 20 percent; no weak diffraction peak appears in the range of 20-25 degrees of 2 theta angle of XRD diffraction pattern of the sample, and no Li corresponding to JCPDS card 27-1252₂MnO₃Diffraction peaks resulting from diffraction.

Example 3

According to the mole ratio of nickel, cobalt, manganese, lithium and doped nitrogen ions of 0.48:0.20:0.29:0.97:0.03 minRespectively weighing nickel nitrate, cobalt acetate, manganese nitrate, lithium nitrate and urea, mixing the nickel nitrate, the cobalt acetate and the manganese nitrate to obtain a mixture 1, adding deionized water with the volume 50 times of the total volume of the mixture 1, uniformly mixing, adding the urea under the condition of continuous stirring, uniformly mixing, dropwise adding ammonia water under the condition of continuous stirring until the acidity of the solution is pH 10.0, adding the weighed lithium nitrate, uniformly mixing by using a ball mill, aging at 50 ℃ and helium atmosphere for 5 hours to obtain a precursor 2, heating the precursor 2 at 120 ℃ under the vacuum condition of 0.9 atmospheric pressure to obtain a dried precursor 3, placing the precursor 3 in an oxygen-enriched air atmosphere with the oxygen volume content of 30%, heating from room temperature to 780 ℃ at the speed of 0.1 ℃/min, cooling to room temperature to obtain layered α -NaFeO₂The nitrogen-doped nickel-cobalt-manganese ternary cathode material has a structure.

The ternary material simultaneously meets the following characteristics that diffraction peaks on an XRD diffraction pattern are all equal to those of layered α -NaFeO of JCPDS card 09-0063₂The characteristic diffraction peaks of the structure are matched; the button half-cell prepared from the prepared ternary material is charged to 4.6V to 4.4V at a constant current relative to a lithium electrode under the conditions of 0.2C rate current and 1 st cycle charge and discharge, and the ratio of the increase of the charging specific capacity is 17 percent; no weak diffraction peak appears in the range of 20-25 degrees of 2 theta angle of XRD diffraction pattern of the sample, and no Li corresponding to JCPDS card 27-1252₂MnO₃Diffraction peaks resulting from diffraction.

Example 4

Nickel chloride, cobalt chloride, manganese nitrate, lithium chloride and urea are respectively weighed according to the molar ratio of nickel to cobalt to manganese to lithium to doped nitrogen ions of 0.58:0.20:0.19:0.95: 0.03. Nickel chloride, cobalt chloride and manganese nitrate were mixed to give mixture 1. Deionized water was added to the mixture in an amount of 30 times the total volume of the mixture 1, and the mixture was mixed well. Adding urea under the condition of continuous stirring, and uniformly mixing. Under the condition of continuous stirring, ammonia water is dripped until the acidity of the solution is pH 10, weighed lithium chloride is added, the mixture is uniformly mixed through a sand mill, and the mixture is aged for 40 hours at 60 ℃ in an argon atmosphere to prepare a precursor 2. The precursor 2 is heated at 160 ℃ under the vacuum condition of 0.01 atmospheric pressure to prepare a dried precursor 3. Placing the precursor 3 in an oxygen atmosphere at 5 ℃Heating to 800 deg.C at min speed, and cooling to room temperature to obtain α -NaFeO with layered structure₂The nitrogen-doped nickel-cobalt-manganese ternary cathode material has a structure.

The ternary material simultaneously meets the following characteristics that diffraction peaks on an XRD diffraction pattern are all equal to those of layered α -NaFeO of JCPDS card 09-0063₂The characteristic diffraction peaks of the structure are matched; the button half-cell prepared from the prepared ternary material is charged to 4.6V to 4.4V at a constant current relative to a lithium electrode under the conditions of 0.2C rate current and 1 st cycle charge and discharge, and the ratio of the increase of the specific charge capacity is 15%; no weak diffraction peak appears in the range of 20-25 degrees of 2 theta angle of XRD diffraction pattern of the sample, and no Li corresponding to JCPDS card 27-1252₂MnO₃Diffraction peaks resulting from diffraction.

Example 5

Weighing nickel hydroxide, cobalt carbonate, manganese chloride, lithium carbonate and melamine according to the molar ratio of nickel, cobalt, manganese, lithium and doped nitrogen ions of 0.78:0.09:0.10:1.10:0.03 respectively, mixing the nickel hydroxide, the cobalt carbonate and the manganese chloride to obtain a mixture 1, adding deionized water with the volume being 1 time of the total volume of the mixture 1, uniformly mixing, adding the melamine under the condition of continuous stirring, uniformly mixing, dropwise adding ammonia water under the condition of continuous stirring until the acidity of the solution is pH 11.0, adding the weighed lithium carbonate, uniformly mixing by using a sand grinding device, aging for 5 hours under the nitrogen atmosphere and the temperature of 90 ℃ to obtain a precursor 2, heating the precursor 2 under the vacuum condition of 0.1 atmospheric pressure at the temperature of 200 ℃ to obtain a dried precursor 3, placing the precursor 3 in an oxygen-enriched air atmosphere with the volume content of 30% of oxygen, heating from the room temperature to the temperature of 890 ℃ at the speed of 0.2 ℃/min, and cooling to the room temperature to obtain the layered α -NaFeO₂The nitrogen-doped nickel-cobalt-manganese ternary cathode material has a structure.

The ternary material simultaneously meets the following characteristics that diffraction peaks on an XRD diffraction pattern are all equal to those of layered α -NaFeO of JCPDS card 09-0063₂The characteristic diffraction peaks of the structure are matched; the button half-cell prepared from the prepared ternary material is charged to 4.6V to 4.4V at a constant current relative to a lithium electrode under the conditions of 0.2C rate current and 1 st cycle charge and discharge, and the ratio of the increase of the specific charge capacity is 20 percent; the 2 theta angle of the XRD diffraction pattern of the sample is 20-25No weak diffraction peak appears in the range of DEG, no Li corresponding to JCPDS cards 27-1252₂MnO₃Diffraction peaks resulting from diffraction.

Example 6

Respectively weighing nickel carbonate, cobalt carbonate, manganese acetate, lithium acetate and acetonitrile according to the molar ratio of nickel, cobalt, manganese, lithium and doped nitrogen ions of 0.82:0.09:0.08:1.10:0.01, mixing the nickel carbonate, the cobalt carbonate and the manganese acetate to obtain a mixture 1, adding deionized water which is 1 time of the total volume of the mixture 1, uniformly mixing, adding the acetonitrile under the condition of continuous stirring, uniformly mixing, dropwise adding ammonia water under the condition of continuous stirring until the acidity of the solution is pH 11.0, adding the weighed lithium acetate, uniformly mixing by using a ball-milling mixing device, aging for 48 hours at 90 ℃ and argon atmosphere to obtain a precursor 2, preparing a dried precursor 3 by using a spray drying method at 190 ℃, placing the precursor 3 in an oxygen atmosphere, heating from room temperature to 920 ℃ at the heating speed of 0.1 ℃/min, cooling to room temperature to obtain the layered NaFeO with α -NaFeO₂The nitrogen-doped nickel-cobalt-manganese ternary cathode material has a structure.

The ternary material simultaneously meets the following characteristics that diffraction peaks on an XRD diffraction pattern are all equal to those of layered α -NaFeO of JCPDS card 09-0063₂The characteristic diffraction peaks of the structure are matched; the button half-cell prepared from the prepared ternary material is charged to 4.6V to 4.4V at a constant current relative to a lithium electrode under the conditions of 0.2C rate current and 1 st cycle charge and discharge, and the ratio of the increase of the charging specific capacity is 15 percent; no weak diffraction peak appears in the range of 20-25 degrees of 2 theta angle of XRD diffraction pattern of the sample, and no Li corresponding to JCPDS card 27-1252₂MnO₃Diffraction peaks resulting from diffraction.

Example 7

Respectively weighing nickel acetate, cobalt chloride, manganese hydroxide, lithium nitrate and melamine according to the molar ratio of nickel to cobalt to manganese to lithium to doped nitrogen ions of 0.80:0.08:0.09:1: 0.03. Nickel acetate, cobalt chloride and manganese hydroxide were mixed to give mixture 1. Deionized water was added in an amount of 50 times the total volume of the mixture 1 and mixed well. And adding melamine under the condition of continuous stirring, and uniformly mixing. Dropwise adding ammonia water under the condition of continuous stirring until the acidity pH of the solution is 13.5, and addingWeighing lithium nitrate, uniformly mixing the lithium nitrate by a common ball mill, aging the mixture for 24 hours at 50 ℃ in an argon atmosphere to prepare a precursor 2, preparing a dried precursor 3 by using a spray drying method for the precursor 2 at 220 ℃, placing the precursor 3 in an oxygen atmosphere, carrying out programmed heating from room temperature to 890 ℃ at a heating speed of 0.2 ℃/min, and cooling to room temperature to prepare α -NaFeO with a layered structure₂The nitrogen-doped nickel-cobalt-manganese ternary cathode material has a structure.

Claims

1. The preparation method of the nitrogen-doped nickel-cobalt-manganese ternary material is characterized by comprising the following steps of: respectively weighing a nickel compound, a cobalt compound, a manganese compound, a lithium compound and a nitrogen dopant according to the molar ratio x, y, z, k and m of nickel, cobalt, manganese, lithium and nitrogen ions; mixing a nickel compound, a cobalt compound and a manganese compound to obtain a mixture 1, and adding deionized water with the volume 1-50 times of the total volume of the mixture 1; adding a nitrogen doping agent under the condition of continuous stirring, and uniformly mixing; dropwise adding ammonia water under the condition of continuous stirring until the acidity of the solution falls within the range of pH 10.0-13.5, adding the weighed lithium compound, and uniformly mixing by using mixing equipment; aging for 5-48 hours at any temperature within a temperature range of 50-90 ℃ in an inert atmosphere of nitrogen, argon or helium without oxygen to prepare a precursor 2; heating the precursor 2 at any temperature within a range of 120-220 ℃ under a vacuum condition with the pressure lower than 1 atmospheric pressure to prepare a dried precursor 3 or preparing the dried precursor 3 at any temperature within a range of 120-220 ℃ by adopting a spray drying method; placing the dried precursor 3 in oxygen-enriched air or oxygen atmosphere, and preparing the nitrogen-doped nickel-cobalt-manganese ternary cathode material by adopting a programmed heating method;

more than two compounds of the nickel compound, the cobalt compound, the manganese compound and the lithium compound are weighed to be soluble in water;

the molar ratio x, y, z, k and m of the nickel ions, the cobalt ions, the manganese ions, the lithium ions and the nitrogen ions simultaneously satisfy the following relation:

x, y, z, m = (0.48-0.52), (0.18-0.20), (0.27-0.30), (0.001-0.03), k is more than or equal to 0.95 and less than or equal to 1.05, and x + y + z + m = 1;

or x, y, z, m = (0.58-0.62), (0.18-0.20), (0.17-0.20), (0.001-0.03), k is more than or equal to 0.95 and less than or equal to 1.05, and x + y + z + m = 1;

or x, y, z, m = (0.78-0.82), (0.08-0.10), (0.001-0.03), k is more than or equal to 0.95 and less than or equal to 1.05, and x + y + z + m = 1;

the ternary material simultaneously satisfies the following characteristics that diffraction peaks on an XRD diffraction pattern and layered α -NaFeO₂The button half cell prepared by the material increases the charging specific capacity by less than 25 percent relative to the constant current charging of a lithium electrode to 4.6V compared with 4.4V under the conditions of 0.2C multiplying current and the 1 st charging and discharging circulation; li which does not correspond to JCPDS card 27-1252 in the range of 20-25 degrees of 2 theta angle of sample XRD diffraction pattern₂MnO₃The diffraction peak of (1).

2. The method for preparing the nitrogen-doped nickel-cobalt-manganese ternary material according to claim 1, wherein the programmed heating method is carried out by placing the dried precursor 3 in oxygen-enriched air or oxygen atmosphere, performing programmed heating from room temperature to any temperature in a temperature range of 780-930 ℃ at a speed of 0.1-5 ℃/min, and cooling to room temperature to obtain the nitrogen-doped nickel-cobalt-manganese ternary cathode material.

3. The method of claim 1, wherein the nitrogen dopant is hydrazine, hydrochloride of hydrazine hydrate, nitrate of hydrazine hydrate, diethylenetriamine, melamine, urea, acetonitrile or ethylenediamine.

4. The method for preparing the nitrogen-doped nickel-cobalt-manganese ternary material according to claim 1, wherein the nickel compound is nickel hydroxide, nickel oxide, nickel nitrate, nickel chloride, basic nickel carbonate, nickel oxalate, nickel acetate or nickel carbonate.

5. The method according to claim 1, wherein the cobalt compound is cobalt hydroxide, cobalt oxide, cobalt nitrate, cobalt chloride, cobalt oxalate, basic cobalt carbonate, cobalt acetate, or cobalt carbonate.

6. The method according to claim 1, wherein the manganese compound is manganese hydroxide, manganese oxide, manganese nitrate, manganese carbonate, manganese oxalate, manganese chloride or manganese acetate.

7. The method according to claim 1, wherein the lithium compound is lithium oxide, lithium nitrate, lithium chloride, lithium carbonate, lithium acetate or lithium hydroxide.

8. The method for preparing the nitrogen-doped nickel-cobalt-manganese ternary material according to claim 1, wherein the oxygen-enriched air is air with an oxygen volume content of 30-99%.

9. The method for preparing the nitrogen-doped nickel-cobalt-manganese ternary material according to claim 1, wherein the mixing equipment is ball milling or sanding equipment.