CN106654222A - High-nickel cathode material, preparation method thereof and lithium ion battery - Google Patents

Abstract

The invention provides a high-nickel positive electrode material, a preparation method thereof and a lithium ion battery. In the invention, the high-nickel positive electrode material doped with non-metallic elements is obtained by adding non-metallic dopant to the precursor of high-nickel positive electrode material, adding lithium source and sintering. This method can make the doping elements evenly distributed in the material, improve the properties of the material surface and increase the stability of the crystal structure, thereby effectively improving the thermal stability of the material, and significantly improving the high-temperature cycle performance and high-temperature storage performance of high-nickel lithium-ion batteries .

Description

A kind of high-nickel positive electrode material and its preparation method and lithium ion battery

technical field

The invention belongs to the field of lithium-ion battery manufacture, and relates to a high-nickel positive electrode material, a preparation method thereof and a lithium-ion battery.

Background technique

With the increasingly prominent problems of energy crisis and environmental pollution, the development of sustainable new energy sources has become a top priority in modern society, and lithium-ion batteries, as a green secondary energy source, have attracted much attention. At present, the commercial lithium-ion battery cathode materials mainly include lithium cobaltate, lithium manganese oxide, lithium iron phosphate and conventional nickel-cobalt lithium manganese oxide ternary materials, but all of them have certain defects and cannot meet the higher energy density of lithium-ion batteries. and other performance requirements. However, high-nickel cathode materials (such as Li(Nix Co _y Al _{1-xy )} O ₂ with _x≥0.7 , Li(Nix Coy Mn _{1-xy )} O ₂ with x≥0.4) have higher specific capacity, Catering to the market's demand for high specific energy batteries, it has gained more and more attention.

However, on the one hand, due to the high nickel content on the surface of the high-nickel cathode material, it is easy to react with the electrolyte at high temperature (>50°C) to generate HF, which causes the dissolution of transition metal ions under the corrosion of HF, making the electrolyte /The electrode interface impedance increases, which reduces the cycle life and storage life of the battery; on the other hand, the Ni ⁴⁺ formed after delithiation of the high-nickel cathode material is poor in stability, especially at high temperatures, Ni ⁴⁺ →Ni ³⁺ reaction, while releasing oxygen, which further deteriorates the cycle performance and storage performance of the battery. These defects have seriously restricted the large-scale popularization and application of high-nickel lithium-ion batteries.

In this field, methods of doping and surface coating have been used to treat high-nickel cathode materials in order to improve the high-temperature cycle performance and high-temperature storage performance of batteries. At present, the commonly used elements for doping are Mg, Al, Ti, Ba, Cu, Zn, Fe, V, Zr, Cr, La, Nb, Ga, F, S, etc., except that F and S are non-metallic elements, The rest are metal elements. However, the compound itself or the oxide formed after thermal decomposition often has a high melting point when doping metal elements, which is not conducive to the sufficient diffusion and uniform distribution of doping elements in the material, and a good doping effect cannot be achieved. . At the same time, most of the oxides corresponding to such metal elements are alkaline or neutral, which is not conducive to reducing the alkalinity of the high-nickel material itself, and it exists in the form of cations in the lattice of the material, which is harmful to the oxygen in the lattice. The stabilizing effect of anion is small and cannot effectively improve the thermal stability of the material. Therefore, it is necessary to provide a more effective method to improve the thermal stability of high-nickel cathode materials and solve the problems of high-temperature cycling and high-temperature storage in their applications. Therefore, how to obtain a high-nickel cathode material with excellent thermal stability has become a technical problem to be solved urgently in this field.

Contents of the invention

In view of the deficiencies in the prior art, one of the purposes of the present invention is to provide a method for preparing a high-nickel positive electrode material to solve the technical problem of poor thermal stability of the high-nickel positive electrode material in the prior art, and the obtained high-nickel lithium ion The battery has excellent high-temperature cycle performance and high-temperature storage performance.

In order to achieve the above object, the present invention adopts the following technical solutions:

A preparation method of high-nickel positive electrode material, comprising the following steps:

A non-metallic dopant is added to a precursor of a high-nickel positive electrode material, a lithium source is added and sintered to obtain a high-nickel positive electrode material doped with non-metallic elements.

The method can make the non-metallic doping elements evenly distributed in the material, improve the properties of the material surface and increase the stability of the crystal structure, thereby effectively improving the thermal stability of the high-nickel positive electrode material, and thus significantly improving the high-nickel lithium-ion battery Excellent high temperature cycle performance and high temperature storage performance.

In the present invention, the high-nickel positive electrode material is Li(Nix Co _y Mn _{1-xy )} O ₂ , where 0.4≤x<1, 0<y≤0.4, for example, x can be 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9 or 0.95, etc., y can be 0.08, 0.12, 0.2, 0.26, 0.33 or 0.4, etc.; or, the high-nickel positive electrode material is Li(Ni _x Co _y Al _1-xy )O ₂ , where 0.7≤x<1, 0<y<0.3, for example, x can be 0.7, 0.8, 0.82, 0.84, 0.86, 0.88, 0.9, 0.92, 0.94 or 0.96, etc., y can be 0.05, 0.08, 0.15, 0.22, 0.25 or 0.28 etc.

In a preferred technical solution of the present invention, the method comprises the following steps:

The precursor of the high-nickel positive electrode material and the non-metallic dopant are dispersed in the liquid phase medium, after being dried, a lithium source is added, and then sintered to obtain the high-nickel positive electrode material.

In a preferred technical solution of the present invention, the method comprises the following steps:

The precursor of the high-nickel positive electrode material, the non-metallic dopant and the lithium source are dispersed in the liquid phase medium, and after drying, sintering is carried out to obtain the high-nickel positive electrode material.

In a preferred technical solution of the present invention, the method comprises the following steps:

The precursor of the high-nickel positive electrode material, the non-metallic dopant and the lithium source are fully mixed, and then sintered to obtain the high-nickel positive electrode material.

In the present invention, the desired high-nickel cathode material is Li(Nix Co _y Mn _{1-xy )} O ₂ , where 0.4≤x<1, 0<y≤0.4, then the precursor of the high-nickel cathode material is Ni One or a combination of at least two of hydroxides, carbonate co-precipitates or oxalate co-precipitates of _x Co _y Mn _1-xy . The precursor of the high-nickel positive electrode material can be, for example, a coprecipitate of hydroxide, carbonate or oxalate of Ni _x Co _y Mn _{1 -xy} , or hydrogen of Ni _x Co _y Mn 1-xy Combination of oxide and carbonate coprecipitate, combination of hydroxide and oxalate coprecipitate, combination of carbonate and oxalate coprecipitate, hydroxide, carbonate and oxalate combination of sediments, etc.

In the present invention, the desired high-nickel cathode material is Li(Nix Co _y Al _{1-xy )} O ₂ , where 0.7≤x<1, 0<y<0.3, then the precursor of the high-nickel cathode material is Ni One or a combination of at least two of hydroxides, carbonate co-precipitates or oxalate co-precipitates of _x Co _y Al _1-xy . The precursor of the high-nickel positive electrode material can be, for example, a co-precipitate of hydroxide, carbonate or oxalate of Ni _x Co _y Al _{1 -xy} , or hydrogen of Ni _x Co _y Al 1-xy Combination of oxide and carbonate coprecipitate, combination of hydroxide and oxalate coprecipitate, combination of carbonate and oxalate coprecipitate, hydroxide, carbonate and oxalate combination of sediments, etc.

In a preferred technical solution of the present invention, the precursor of the high-nickel positive electrode material is a pre-calcined precursor. The atmosphere of the calcining treatment is air, the temperature of the calcining treatment is between 200-1000°C, and the time of the calcining treatment is 1-30 hours.

The temperature of the pre-calcination treatment can be, for example, 210°C, 255°C, 283°C, 330°C, 392°C, 452°C, 530°C, 608°C, 677°C, 720°C, 780°C, 855°C, 890°C, 914°C ℃ or 990℃, etc. The time for the pre-burning treatment may be, for example, 1 h, 2.2 h, 3.5 h, 4 h, 5.5 h, 7 h, 11.5 h, 15 h, 18 h, 22.5 h, 27 h, or 29.5 h.

In a preferred technical solution of the present invention, the non-metal dopant is one or a combination of at least two compounds containing non-metal elements such as silicon, phosphorus or boron. The compounds containing non-metallic elements such as silicon, phosphorus or boron include but are not limited to: lithium silicate, lithium metasilicate, ammonium silicate, ammonium metasilicate, silicate, lithium phosphate, lithium hydrogen phosphate, Lithium dihydrogen phosphate, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, phosphoric acid, pyrophosphoric acid, phosphorus pentoxide, lithium pyroborate, lithium metaborate, ammonium pyroborate, ammonium metaborate, boric acid, metaboric acid, pyroboric acid or boron trioxide. In addition, the non-metallic dopant may also be a combination of at least two of the above-mentioned compounds. For example, the non-metallic dopant can be lithium silicate, ammonium metasilicate, lithium hydrogen phosphate, ammonium dihydrogen phosphate, pyrophosphoric acid, lithium borate, pyroboric acid, or a combination of ammonium silicate and phosphorus pentoxide, The combination of tetrabutyl silicate and diboron trioxide, the combination of ammonium dihydrogen phosphate and lithium metaborate, the combination of pyrophosphoric acid, lithium silicate and ammonium metaborate, etc.

Since the lithium salt formed by the dopant containing silicon, phosphorus, boron and other non-metallic elements after sintering is electrochemically active, and its specific capacity is close to or even higher than the theoretical specific capacity of the high-nickel positive electrode material, so after doping, it will not It will cause the specific capacity of the material to decrease.

In a preferred technical solution of the present invention, the amount of the non-metallic dopant used is 0.1%-10% of the mass of the precursor of the high-nickel positive electrode material. For example, the dosage of the dopant may be 0.1%, 0.3%, 0.5%, 1.1%, 1.8%, 4%, 6.5%, 7.2% or 9.5% of the mass of the precursor of the high-nickel cathode material.

In a preferred technical solution of the present invention, the liquid phase medium may be one or a combination of at least two of water, alcohol (ethanol) or glycerin. The combination may be, for example, a combination of water and alcohol, a combination of water and glycerin, a combination of alcohol and glycerin, a combination of water, alcohol and glycerin.

In a preferred technical solution of the present invention, the amount of the liquid phase medium is 1/10 to 10 times the mass of the precursor of the high-nickel positive electrode material. The amount of the liquid phase medium can be, for example, 1/2, 2, 4.5, 7, 8.5, 9 or 10 times the mass of the precursor of the high-nickel cathode material.

In a preferred technical solution of the present invention, the dispersion method is one of magnetic stirring, mechanical stirring, ultrasonic oscillation, ball milling or three-dimensional mixing.

In a preferred technical solution of the present invention, the dispersion is sufficient dispersion.

In a preferred technical solution of the present invention, the drying is carried out in drying equipment, the drying temperature is 40-400° C., and the drying time is 1-48 hours. The drying temperature may be, for example, 80°C, 115°C, 180°C, 270°C, 310°C, 350°C, 370°C or 390°C. The drying time can be, for example, 2.5h, 6h, 9h, 12h, 15h, 17h, 20h, 22h, 25h, 28h, 31h, 34h, 37h, 40h, 43h or 46h.

In the present invention, depending on the precursor of the high-nickel positive electrode material, the non-metal dopant, the liquid phase medium and the lithium source, what is obtained after drying can be the precursor of the high-nickel positive electrode material and the non-metal doped It can also be a physical mixture of dopant and/or lithium source, or a mixed product after the reaction of non-metallic dopant with the precursor of high-nickel positive electrode material and/or liquid phase medium and/or lithium source. For example, the non-metallic dopant is lithium phosphate, the precursor of the high-nickel positive electrode material is the carbonate of Ni _x Co _y Mn _1-xy , and the liquid phase medium is alcohol, then what is obtained after drying is Ni _x Co _y Carbonate of Mn _1-xy is a physical mixture with lithium phosphate. For another example, the non-metallic dopant is phosphorus pentoxide, the precursor of the high-nickel positive electrode material is Ni _x Co _y Al _1-xy hydroxide, and the liquid phase medium is water. Because phosphorus pentoxide reacts with liquid medium water to generate phosphoric acid, phosphoric acid further reacts with part of the hydroxide of Ni _x Co _y Al 1- _xy to generate the phosphate of Ni _x Co _y Al _1-xy , therefore, after drying, is a mixture of Ni _x Co _y Al _1-xy hydroxide and phosphate.

In a preferred technical solution of the present invention, the lithium source is one or a combination of at least two of lithium acetate, lithium sulfate, lithium hydroxide, lithium nitrate or lithium carbonate. The combination can be, for example, a combination of lithium acetate and lithium sulfate, a combination of lithium acetate and lithium hydroxide, a combination of lithium nitrate and lithium carbonate, a combination of lithium acetate, lithium sulfate and lithium hydroxide or lithium nitrate, lithium carbonate and sulfuric acid Combinations of lithium, etc.

In a preferred technical solution of the present invention, the lithium source is added in an amount of 0.9 to 1.2 times the stoichiometric ratio. The added amount of the lithium source can be added in proportions such as 0.92 times, 0.97 times, 1 time, 1.06 times, 1.10 times, 1.15 times, 1.2 times, etc. of the stoichiometric ratio. The addition amount of the lithium source is determined according to the precursor of the high-nickel positive electrode material, the non-metallic dopant, or the sintering process conditions (such as sintering temperature, time) and other factors. The amount of lithium source used in the comparative examples and examples in this specification is typical and non-limiting.

In a preferred technical solution of the present invention, the sintering atmosphere is air, oxygen or a mixed gas of nitrogen and oxygen in a certain volume ratio. The sintering atmosphere may be, for example, air, oxygen, or a gas in which nitrogen and oxygen are mixed in volume ratios of 1:9, 1:4, 2:3, 1:1, and 7:3.

In a preferred technical solution of the present invention, the sintering temperature is 400-1000° C., and the sintering time is 4-48 hours. The sintering temperature can be, for example, 450°C, 500°C, 550°C, 580°C, 600°C, 650°C, 700°C, 735°C, 750°C, 800°C, 810°C, 850°C, 900°C, 950°C or 980°C etc. The sintering time may be, for example, 5h, 7.5h, 9h, 13h, 18h, 25h, 29h, 33h, 40h, 45h or 48h.

The second object of the present invention is to provide a high-nickel positive electrode material obtained by the above-mentioned preparation method of high-nickel positive electrode material. The high-nickel cathode material obtained by the method has excellent thermal stability.

The third object of the present invention is to provide a lithium ion battery, which uses the above-mentioned high-nickel positive electrode material as the positive electrode material. By adopting the high-nickel positive electrode material as the positive electrode material, the obtained lithium ion battery has excellent high-temperature cycle performance and high-temperature storage performance.

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

(1) In the method of the present invention, the non-metallic dopant is added in the process of the precursor processing the finished product, and does not need to be introduced when the precursor is prepared, avoiding the co-precipitation or secondary precipitation of the non-metallic dopant and the precursor Complicated process requirements, the method is simple and easy;

(2) The preferred non-metallic elements used in the present invention are combined with oxygen atoms in the form of covalent bonds in the crystal lattice of the high-nickel positive electrode material, which has higher bond energy, making its crystal structure more stable under high temperature conditions, Oxygen in the lattice is not easy to be oxidized and precipitated by Ni ⁴⁺ formed in the delithiated state, thereby improving the thermal stability of the material;

(3) The lithium salt formed by the non-metallic dopant preferably used in the present invention after high-temperature sintering is neutral or weakly alkaline, which can reduce the alkalinity of the high-nickel positive electrode material on the whole, and improve the properties of the material surface, thereby Improve the high temperature cycle life and high temperature storage life of the battery;

(4) The preferred non-metallic dopant used in the present invention itself or the compound formed after thermal decomposition has a lower melting point, which is conducive to the sufficient diffusion and uniform distribution of doping elements in the material, so as to achieve better doping Effect.

The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable , the specific embodiments of the present invention are enumerated below.

detailed description

Exemplary embodiments of the present disclosure will be described in more detail below. Although exemplary embodiments of the present disclosure are shown below, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided for more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. It should be understood that those skilled in the art can conceive of various methods, components and contents that realize the present invention and are included in the spirit, principle and scope of the present invention although not explicitly described or recorded in the specification. All examples and conditional language cited in this specification are for the purpose of illustration and teaching to help the reader understand the principles and concepts of the inventor's contribution to the prior art, and should be understood as not being limited to those specifically cited Examples and Conditions. In addition, for clearer description, detailed descriptions of known methods, components and contents are omitted so as not to obscure the description of the present invention. It should be understood that, unless otherwise specified, the features in the various embodiments described herein can be combined with each other.

Comparative example 1:

100 parts by mass of Ni, Co, Mn in a molar ratio of 5:2:3 carbonate coprecipitate precursor and 32.36 parts by mass of lithium carbonate (99.0%) were mixed in a three-dimensional mixer at 25Hz for 4h, Then put it in a box-type furnace for pre-calcination at 680°C for 6 hours in an air atmosphere; after cooling to room temperature, re-sinter at 960°C for 12 hours in an oxygen atmosphere, and pass through a 400-mesh standard sieve after cooling to obtain a conventional nickel-cobalt lithium manganate cathode material. The exothermic peak temperature of the obtained cathode material was tested by differential scanning calorimetry (DSC). The obtained positive electrode material, binder PVDF, and conductive agent acetylene black are mixed in the oil solvent NMP according to the mass ratio of 96:2:2 to obtain a uniform positive electrode slurry, and the prepared positive electrode slurry is evenly coated on the On the positive electrode current collector Al foil, dry in a convection drying oven at 120°C, 130°C, and 128°C for 10 minutes respectively to obtain a positive electrode sheet, and roll the positive electrode sheet with a compact density of 3.35g/cm ³ for use. The positive electrode sheet was assembled into a polymer pouch battery according to the traditional manufacturing process, and the cycle performance of the battery at 45°C, 3.0-4.2V, and 1C rate was tested, and the battery state change after being stored at 60°C for 7 days in a fully charged state.

Example 1:

200 parts by mass of Ni, Co, Mn in a molar ratio of 5:2:3 carbonate coprecipitate precursor and 1.8 parts by mass of lithium metasilicate were added to 200 parts by mass of deionized water and dispersed under mechanical stirring 2h to obtain the slurry; dry the resulting slurry at 120°C for 12h to obtain the precursor mixture; weigh 100 parts of the mass of the precursor mixture, add 31.76 parts of the mass of lithium carbonate (99.0%), in a three-dimensional mixer under the condition of 25Hz Mixed at low temperature for 4 hours, and then placed in a box-type furnace under an air atmosphere at 680°C for 6 hours; after cooling to room temperature, re-sintered at 960°C under an oxygen atmosphere for 12 hours, and passed through a 400-mesh standard sieve after cooling to obtain silicon doped Nickel cobalt lithium manganese oxide cathode material, also using DSC to test its exothermic peak temperature. Subsequently, according to the process conditions described in Comparative Example 1, the obtained positive electrode material was used to manufacture a polymer pouch battery of the same type, and its high-temperature cycle performance and high-temperature storage performance were also tested.

Example 2:

According to the same component content and process conditions in Example 1, the nickel-cobalt lithium manganate positive electrode material was prepared, but the quality of lithium metasilicate was increased from 1.8 parts to 3.6 parts, and the quality of lithium carbonate was reduced from 31.76 parts to 31.48 parts. Parts, the nickel-cobalt-lithium-manganese-oxide cathode material doped with silicon was obtained, and the exothermic peak temperature was also measured by DSC. Subsequently, according to the process conditions described in Comparative Example 1, the obtained positive electrode material was used to manufacture a polymer pouch battery of the same type, and its high-temperature cycle performance and high-temperature storage performance were also tested.

Example 3:

According to the same component content and process conditions in Example 1, the nickel-cobalt lithium manganese oxide positive electrode material was prepared, but the quality of lithium metasilicate was reduced from 1.8 parts to 0.08 parts, and the quality of lithium carbonate was increased from 31.76 parts to 32.03 parts. Parts, the nickel-cobalt-lithium-manganese-oxide cathode material doped with silicon was obtained, and the exothermic peak temperature was also measured by DSC. Subsequently, according to the process conditions described in Comparative Example 1, the obtained positive electrode material was used to manufacture a polymer pouch battery of the same type, and its high-temperature cycle performance and high-temperature storage performance were also tested.

Example 4:

According to the same component content and process conditions in Example 1, the nickel-cobalt lithium manganese oxide positive electrode material was prepared, but the quality of lithium metasilicate was increased from 1.8 parts to 20 parts, and the quality of lithium carbonate was reduced from 31.76 parts to 29.13 parts. Parts, the nickel-cobalt-lithium-manganese-oxide cathode material doped with silicon was obtained, and the exothermic peak temperature was also measured by DSC. Subsequently, according to the process conditions described in Comparative Example 1, the obtained positive electrode material was used to manufacture a polymer pouch battery of the same type, and its high-temperature cycle performance and high-temperature storage performance were also tested.

Example 5:

99.11 parts by mass of Ni, Co, Mn in a molar ratio of 5:2:3 carbonate coprecipitate precursor, 0.89 parts by mass of lithium metasilicate and 31.76 parts by mass of lithium carbonate (99.0%) were added to 100 parts Quality deionized water was dispersed under mechanical stirring for 2 hours to obtain a slurry; the resulting slurry was dried at 120°C for 12 hours to obtain a precursor mixture, and then placed in a box furnace under an air atmosphere at 680°C for 6 hours; cooled After reaching room temperature, it was re-sintered at 960°C for 12 hours in an oxygen atmosphere, and passed through a 400-mesh standard sieve after cooling to obtain a silicon-doped nickel-cobalt lithium manganate cathode material. The exothermic peak temperature was also tested by DSC. Subsequently, according to the process conditions described in Comparative Example 1, the obtained positive electrode material was used to manufacture a polymer pouch battery of the same type, and its high-temperature cycle performance and high-temperature storage performance were also tested.

Embodiment 6:

99.11 parts by mass of Ni, Co, Mn in a molar ratio of 5:2:3 carbonate coprecipitate precursor, 0.89 parts by mass of lithium metasilicate and 31.76 parts by mass of lithium carbonate (99.0%), in three-dimensional Mix in a mixer for 4 hours at 25 Hz, then pre-sinter in a box furnace at 680°C for 6 hours in an air atmosphere; after cooling to room temperature, re-sinter at 960°C in an oxygen atmosphere for 12 hours, and pass through a 400-mesh standard sieve after cooling to obtain The silicon-doped nickel-cobalt-lithium manganese oxide cathode material was also tested by DSC for its exothermic peak temperature. Subsequently, according to the process conditions described in Comparative Example 1, the obtained positive electrode material was used to manufacture a polymer pouch battery of the same type, and its high-temperature cycle performance and high-temperature storage performance were also tested.

Comparative example 2:

Put 200 parts of the hydroxide precursor with a molar ratio of Ni, Co and Al of 8:1.5:0.5 in a box furnace for pre-calcination at 500°C for 7.5 hours, and after cooling, take 100 parts of the mass for pre-calcination Add 89.31 parts of mass lithium acetate (99.0%) to the processed precursor, mix it in a three-dimensional mixer at 25 Hz for 4 hours, then place it in a box furnace for sintering at 780° C. for 10 hours under an oxygen atmosphere, and pass through a 400-mesh standard sieve after cooling , to obtain the conventional nickel cobalt lithium manganese oxide cathode material. The exothermic peak temperature of the obtained cathode material was tested by differential scanning calorimetry (DSC). According to the process conditions described in Comparative Example 1, only the compacted density was increased from 3.35g/ ^cm3 to 3.55g/ ^cm3 , and the positive electrode sheet was rolled, and assembled into a polymer pouch battery according to the traditional manufacturing process, and the test battery was in Cycling performance at 45°C, 3.0-4.2V, 1C rate, and battery state changes after 7 days of storage at 60°C in a fully charged state.

Embodiment 7:

Put 300 parts of the hydroxide precursor with a molar ratio of Ni, Co and Al of 8:1.5:0.5 in a box furnace for pre-calcination at 500°C for 7.5 hours in an air atmosphere. After cooling, take 200 parts of the mass for pre-calcination The treated precursor, 2.4 parts by mass of dilithium hydrogen phosphate, was added to 240 parts by mass of deionized water, and dispersed under mechanical stirring for 0.5 h to obtain a slurry; the obtained slurry was dried at 130 ° C for 20 h to obtain a precursor mixture; Weigh 100 parts by mass of the precursor mixture, add 88.96 parts by mass of lithium acetate (99.0%), mix it in a three-dimensional mixer at 25 Hz for 4 h, then place it in a box furnace for sintering at 780 ° C for 12 h in an oxygen atmosphere, after cooling Pass through a 400-mesh standard sieve to obtain a nickel-cobalt-lithium-aluminate cathode material doped with phosphorus, and use DSC to test its exothermic peak temperature. Then, according to the process conditions described in Comparative Example 2, the obtained positive electrode material was used to manufacture a polymer pouch battery of the same type, and its high-temperature cycle performance and high-temperature storage performance were also tested.

Embodiment 8:

According to the same component content and process conditions in Example 3, nickel cobalt lithium manganese oxide positive electrode material was prepared, except that 2.4 parts of mass of dilithium hydrogen phosphate were replaced with 2.4 parts of mass of dilithium hydrogen phosphate and 2.4 parts of mass of pyroboric acid , and the mass of lithium acetate was reduced from 88.96 parts to 88.92 parts, and a nickel-cobalt-lithium-aluminate cathode material doped with phosphorus and boron elements was obtained, and the exothermic peak temperature was also tested by DSC. Then, according to the process conditions described in Comparative Example 2, the obtained positive electrode material was used to manufacture a polymer pouch battery of the same type, and its high-temperature cycle performance and high-temperature storage performance were also tested.

Afterwards, the performances of the positive electrode materials and lithium-ion batteries prepared in the above comparative examples and examples were compared, and the comparison results are shown in Table 1.

Table 1 The performance comparison table of positive electrode material and lithium-ion battery prepared by each comparative example and embodiment

It can be seen from the above table:

(1) The thermal stability of the positive electrode material prepared by Example 1, Example 2, Example 4 and Example 5 is better than that of the positive electrode material prepared by Comparative Example 1, and the high temperature cycle performance of its corresponding lithium ion battery and high-temperature storage performance are also significantly better than the lithium-ion battery prepared in Comparative Example 1;

(2) Comparing the positive electrode materials prepared in Example 1, Example 2, Example 3 and Example 4 and the performance results of lithium ion batteries, it can be seen that increasing the amount of non-metallic dopant can further improve the thermal stability of positive electrode materials performance and the high-temperature cycle performance and high-temperature storage performance of its lithium-ion battery, but further increasing the amount of the dopant can not greatly improve the performance of the positive electrode material and its lithium-ion battery, and the amount of non-metallic dopant is too low , it will hardly improve the performance of the positive electrode material and its lithium-ion battery;

(3) Comparative Example 5, Example 1 and Comparative Example 1 prepared positive electrode materials and performance results of lithium-ion batteries. In the case of a liquid medium, its performance is better than that of the positive electrode material prepared in Comparative Example 1 and its ion battery, and is substantially close to the performance of the positive electrode material prepared in Example 1 and its lithium ion battery;

(4) Comparing the positive electrode material prepared by Example 6, Example 1 and Comparative Example 1 and the performance results of the lithium-ion battery thereof, it can be seen that without using a liquid medium, its performance is worse than that prepared by Comparative Example 1 positive electrode material and its ion battery, but not as good as the performance of the positive electrode material prepared in Example 1 and its lithium ion battery;

(5) The positive electrode materials prepared in Examples 7 and 8 are significantly better than the positive electrode materials prepared in Comparative Example 2, and the high-temperature cycle performance and high-temperature storage performance of the corresponding lithium-ion batteries are also significantly better than those in Comparative Example 2. Prepared lithium ion battery;

(6) Comparing the performance results of positive electrode materials prepared in Examples 7 and 8 and their lithium-ion batteries, adding one or more dopants simultaneously can further improve the thermal stability of positive electrode materials and their lithium-ion batteries. Excellent high temperature cycle performance and high temperature storage performance.

It shows that the technical means provided by the present invention have the expected effect of improving the thermal stability of high-nickel cathode materials for lithium-ion batteries, and significantly improving the high-temperature cycle performance and high-temperature storage performance of lithium-ion batteries.

Claims (10)

1. a preparation method of high-nickel positive electrode material, comprising the following steps: A non-metallic dopant is added to a precursor of a high-nickel positive electrode material, a lithium source is added and sintered to obtain a high-nickel positive electrode material doped with non-metallic elements. 2. The method according to claim 1, wherein the high-nickel cathode material is Li(NixCoyMn1 _{-xy ) O2} , wherein _0.4≤x <1, 0<y≤0.4; or Li(Nix Coy Al _{1-xy )} O ₂ , where 0.7≤x<1, 0< _y <0.3. 3. The method according to claim 1 or 2, comprising the steps of: Disperse the precursor of the high-nickel cathode material and non-metallic dopant in the liquid medium, add lithium source after drying, and then sinter to obtain the high-nickel cathode material; Preferably, the precursor of the high-nickel positive electrode material, the non-metallic dopant and the lithium source are dispersed in the liquid medium, and after drying, sintering is carried out to obtain the high-nickel positive electrode material; Preferably, the precursor of the high-nickel positive electrode material, the non-metallic dopant and the lithium source are fully mixed, and then sintered to obtain the high-nickel positive electrode material. 4. The method according to one of claims 1-3, characterized in that the precursor of the high-nickel cathode material is Ni _x Co _y Mn _1-xy hydroxide, carbonate coprecipitate or oxalate One or a combination of at least two of the co-precipitates, where 0.4≤x<1, 0<y≤0.4; Preferably, the precursor of the high-nickel positive electrode material is one or a combination of at least two of Ni _x Co _y Al _1-xy hydroxide, carbonate coprecipitate or oxalate coprecipitate, Among them, 0.7≤x<1, 0<y<0.3; Preferably, the precursor of the high-nickel cathode material is a pre-sintered precursor; Preferably, the atmosphere of the pre-sintering treatment is air, the temperature of the pre-sintering treatment is 200-1000° C., and the time of the pre-sintering treatment is 1-30 hours. 5. The method according to any one of claims 1-4, wherein the non-metallic dopant is one or at least two combinations of silicon-containing, phosphorus-containing or boron-containing compounds; Preferably, the silicon-, phosphorus-, and boron-containing compounds include: lithium silicate, lithium metasilicate, ammonium silicate, ammonium metasilicate, silicate, lithium phosphate, lithium hydrogen phosphate, lithium dihydrogen phosphate , ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, phosphoric acid, pyrophosphoric acid, phosphorus pentoxide, lithium pyroborate, lithium metaborate, ammonium pyroborate, ammonium metaborate, boric acid, metaboric acid, pyroboric acid or dioxide One or a combination of at least two of boron; Preferably, the amount of the non-metallic dopant is 0.1%-10% of the mass of the precursor of the high-nickel positive electrode material. 6. The method according to any one of claims 3-5, wherein the liquid phase medium is one or a combination of at least two of water, alcohol or glycerin; Preferably, the amount of the liquid phase medium is 1/10 to 20 times the mass of the precursor of the high nickel positive electrode material. 7. The method according to any one of claims 3-6, wherein the dispersion method is one of magnetic stirring, mechanical stirring, ultrasonic oscillation, ball milling or three-dimensional mixing; Preferably, the drying is carried out in drying equipment, the drying temperature is 40-400° C., and the drying time is 1-48 hours. 8. The method according to one of claims 3-7, wherein the lithium source is one or at least two combinations of lithium acetate, lithium sulfate, lithium hydroxide, lithium nitrate or lithium carbonate; Preferably, the lithium source is added in an amount of 0.9 to 1.2 times the stoichiometric ratio; Preferably, the sintering atmosphere is air, oxygen or a mixed gas of nitrogen and oxygen; Preferably, the sintering temperature is 400-1000° C., and the sintering time is 4-48 hours. 9. A high-nickel positive electrode material obtained by the method for preparing the high-nickel positive electrode material according to any one of claims 1-8. 10. A lithium ion battery, said lithium ion battery uses the high-nickel positive electrode material as claimed in claim 9 as the positive electrode material.