CN117440934A - Ternary positive electrode material and preparation method and application thereof - Google Patents

Abstract

The present disclosure provides a ternary positive electrode material, a preparation method and applications thereof, wherein the preparation method comprises the following steps: (1) Mixing a nickel source, a cobalt source and a solvent, freezing to obtain a refrigerating fluid A, mixing an aluminum source, a complexing agent and the solvent, freezing to obtain a refrigerating fluid B, crushing the refrigerating fluid A and the refrigerating fluid B at a low temperature, and pressing and freezing to obtain a refrigerating fluid C; (2) Placing the frozen liquid C in a reflux device, and controlling the alkaline reflux liquid to reflux between the reflux device and the reaction device until the frozen liquid C is completely melted to obtain a suspension; (3) And (3) carrying out solid-liquid separation on the suspension, mixing the obtained solid product with a lithium source, and sintering to obtain the ternary anode material. The method adopts simple reflux melting operation, can ensure the element proportion of the material through simple operation, realizes the uniform coprecipitation of nickel, cobalt and aluminum, does not need to use ammonia complexing agent, reduces environmental pollution, and has uniform element distribution and high lattice order degree of the prepared ternary anode material.

Description

A ternary cathode material and its preparation method and application

Technical field

The present disclosure belongs to the technical field of lithium-ion batteries and relates to a ternary cathode material and its preparation method and application.

Background technique

At present, lithium-ion batteries have been widely used in various energy storage scenarios, such as mobile phones, notebooks, new energy vehicles, etc. The representative material, lithium nickel cobalt oxide, has good energy density, but has shortcomings such as poor overcharge resistance and poor thermal stability. In order to solve the above problems, domestic and foreign scholars have conducted a large number of experiments. The experiments have proved that the doping of aluminum ions can stabilize the material structure, increase the lithium ion diffusion coefficient, and significantly inhibit the thermochemical reaction of the material.

However, there are major problems in the preparation method of nickel-cobalt-aluminum hydroxide precursor, making it difficult to produce on a large scale. This is because the solubility constant of aluminum hydroxide is on the order of 10 ^-33 , while the solubility product of nickel and cobalt is on the order of 10 ^-15 , which makes the precipitation rate of aluminum ions much greater than that of nickel and cobalt ions. It is difficult to co-precipitate with nickel and cobalt ions into spherical particles. Therefore, the cathode material obtained by calcining the precursor doped with aluminum has loose particles and poor structural stability.

CN104425815A uses two or more mixed complexing agents to pre-complex the aluminum salt solution, and then adds the aluminum complex solution, nickel-cobalt solution and precipitant to the reactor at a certain flow rate for reaction, which obtains the aluminum complex in advance The solution method improves the problem that aluminum ions form Al(OH) ₃ in aqueous solution significantly faster than nickel and cobalt ions, thereby obtaining a precursor material with evenly dispersed elements.

CN115215388A discloses a preparation method of a ternary cathode material and a ternary cathode material. The method includes: mixing manganese salts and/or aluminum salts with nickel salts and cobalt salts, and mixing them with alkaline substances and complexing agents in a solvent. A co-precipitation reaction is carried out to obtain a co-precipitation slurry with a target median particle size; the co-precipitation slurry is washed to obtain a ternary precursor slurry; in an inert atmosphere, the lithium source and the ternary precursor are The slurry is mixed to obtain a first mixture; the first mixture is dried to obtain a second mixture; the second mixture is subjected to high-temperature sintering to obtain the ternary cathode material.

Complexing agents that can complex with aluminum can usually complex with nickel and cobalt. When the aluminum complexing solution and nickel and cobalt solution are added to the reactor in the above scheme, the excess complexing agent in the aluminum complexing solution will react with the unprecipitated nickel. Cobalt complexes, reducing the precipitation rate of nickel and cobalt, and increasing the difference in precipitation rates between nickel, cobalt, and aluminum, which is not conducive to the atomic level mixing of nickel, cobalt, and aluminum elements.

Contents of the invention

The following is an overview of the topics described in detail in this article. This summary is not intended to limit the scope of the claims.

The purpose of this disclosure is to provide a ternary cathode material and its preparation method and application. This disclosure adopts a simple reflow melting operation, which can ensure the element ratio of the material through a simple operation and achieve uniform co-precipitation of nickel, cobalt and aluminum. The method does not require the use of an ammonia complexing agent, reduces environmental pollution, and produces a ternary cathode material with uniform element distribution and high lattice order.

To achieve this goal, this disclosure adopts the following technical solutions:

In a first aspect, the present disclosure provides a method for preparing a ternary cathode material. The preparation method includes the following steps:

(1) Mix the nickel source, cobalt source and solvent, freeze to obtain freezing liquid A, mix the aluminum source, complexing agent and solvent, adjust the pH and freeze to obtain freezing liquid B, crush freezing liquid A and freezing liquid B at low temperature , press and freeze to obtain freezing liquid C;

(2) Place the frozen liquid C in a reflux device, control the alkaline reflux liquid to reflux between the reflux device and the reaction device, and control the temperature and pH in the system until the frozen liquid C is completely melted to obtain a suspension;

(3) Perform solid-liquid separation treatment on the suspension, mix the obtained solid product with a lithium source, and sinter to obtain the ternary cathode material.

In this disclosure, the frozen Ni/Co mixed solution and the frozen Al ³⁺ complexing agent mixed solution are placed in a reflux chamber, and the alkali solution is refluxed and melted, so that the reaction of aluminum precipitation proceeds slowly, and during this reaction process, the alkali solution Precipitation occurs with nickel and cobalt ions, and the complexing agent only acts on aluminum ions, so it can avoid the use of complexing agents to reduce the precipitation rate of nickel and cobalt ions.

In one embodiment, the nickel source in step (1) includes any one or a combination of at least two of nickel sulfate, nickel nitrate, nickel chloride or nickel acetate.

In one embodiment, the cobalt source includes any one or a combination of at least two of cobalt sulfate, cobalt nitrate, cobalt chloride or cobalt acetate.

In one embodiment, the concentration of the nickel source in the freezing liquid A is 0.1-1 mol/L, for example: 0.1 mol/L, 0.3 mol/L, 0.5 mol/L, 0.8 mol/L or 1 mol/L, etc.

In one embodiment, the concentration of the cobalt source in the freezing liquid A is 0.1-1 mol/L, for example: 0.1 mol/L, 0.3 mol/L, 0.5 mol/L, 0.8 mol/L or 1 mol/L, etc.

In one embodiment, the total concentration of the cobalt source and the nickel source in the freezing liquid A is 0.5 to 2 mol/L, for example: 0.5 mol/L, 0.8 mol/L, 1 mol/L, 1.5 mol/L or 2 mol/L. L et al.

In one embodiment, the aluminum source in step (1) includes any one or a combination of at least two of aluminum nitrate, aluminum sulfate or aluminum chloride.

In one embodiment, the complexing agent includes any one or a combination of at least two of acetylacetone, oxalic acid, salicylic acid or sulfosalicylic acid.

In one embodiment, the pH adjusting agent includes sulfuric acid and/or hydrochloric acid.

In one embodiment, the pH is 2 to 5, such as: 2, 2.5, 3, 4 or 5, etc.

In one embodiment, the concentration of the aluminum source in the freezing liquid B is 0.1-1 mol/L, for example: 0.1 mol/L, 0.3 mol/L, 0.5 mol/L, 0.8 mol/L or 1 mol/L, etc.

In one embodiment, the concentration of the complexing agent in the freezing liquid B is 0.1 to 0.5 mol/L, for example: 0.1 mol/L, 0.2 mol/L, 0.3 mol/L, 0.4 mol/L or 0.5 mol/L. L et al.

In one embodiment, the freezing temperature in step (1) is -30 to -50°C, for example: -30°C, -35°C, -40°C, -45°C or -50°C, etc.

In one embodiment, the freezing time is 6 to 12 hours, for example: 6 hours, 7 hours, 8 hours, 10 hours or 12 hours, etc.

In one embodiment, the temperature of the low-temperature crushing treatment is <-10°C.

In one embodiment, the pressing pressure is 0.1 to 10 MPa, for example: 0.1 MPa, 0.5 MPa, 1 MPa, 5 MPa or 10 MPa, etc.

In one embodiment, the molar ratio of nickel element, cobalt element and aluminum element in the refrigerant liquid C is (0.6~0.9):(0.08~0.3):(0.02~0.1), for example: 0.6:0.08:0.02, 0.7:0.1:0.05, 0.8:0.2:0.08, 0.8:0.25:0.05 or 0.9:0.3:0.1, etc.

In one embodiment, the alkaline reflux liquid in step (2) includes sodium hydroxide solution and/or potassium hydroxide solution.

In one embodiment, the pH of the alkaline reflux liquid is 10.5-12, for example: 10.5, 11, 11.5, 11.8 or 12, etc.

In one embodiment, the reflux speed of the alkaline reflux liquid is 10 to 200 mL/min, for example: 10 mL/min, 20 mL/min, 50 mL/min, 100 mL/min or 200 mL/min, etc.

In one embodiment, the method of controlling the pH in the system in step (2) includes adding alkaline solution.

In one embodiment, the pH is 10.5-12, for example: 10.5, 11, 11.5, 11.8 or 12, etc.

In one embodiment, the concentration of the alkali solution is 5 to 10 mol/L, for example: 5 mol/L, 6 mol/L, 7 mol/L, 8 mol/L or 10 mol/L, etc.

In one embodiment, the temperature in the system is 40-70°C, for example: 40°C, 50°C, 60°C, 65°C or 70°C, etc.

In one embodiment, the frozen liquid C is aged after all of it is melted.

In one embodiment, the aging treatment time is 2 to 20 hours, such as: 2 hours, 5 hours, 10 hours, 15 hours, 20 hours, etc.

In one embodiment, the lithium source in step (3) includes lithium hydroxide and/or lithium carbonate.

In one embodiment, the total molar ratio of the lithium element in the lithium source and the metal element in the solid product is (1-1.1):1, for example: 1:1, 1.02:1, 1.05:1, 1.08:1 Or 1.1:1 etc.

In one embodiment, the sintering includes one-stage sintering and two-stage sintering.

In one embodiment, the sintering temperature of the first stage is 300-650°C, for example: 300°C, 350°C, 400°C, 500°C or 650°C, etc.

In one embodiment, the sintering time ranges from 2 to 10 hours, such as 2 hours, 5 hours, 6 hours, 8 hours or 10 hours.

In one embodiment, the temperature of the second-stage sintering is 700-850°C, such as 700°C, 750°C, 780°C, 800°C or 850°C.

In one embodiment, the second-stage sintering time is 8 to 20 hours, for example: 8 hours, 9 hours, 10 hours, 15 hours, 20 hours, etc.

In a second aspect, the present disclosure provides a ternary cathode material, which is prepared by the method described in the first aspect.

The three transition metal elements in the ternary cathode material of the present disclosure are evenly distributed in the spherical particles, which improves the lattice order of the material. The tap density of the lithium nickel cobalt aluminate cathode material is high and has good performance. electrochemical properties such as discharge specific capacity and cycle stability.

In a third aspect, the present disclosure provides a positive electrode piece, which includes the ternary positive electrode material as described in the second aspect.

In a fourth aspect, the present disclosure provides a lithium ion battery, which includes the positive electrode plate as described in the third aspect.

Compared with the existing technology, the present disclosure has the following beneficial effects:

(1) In this disclosure, the frozen Ni/Co mixed solution and the frozen Al ³⁺ complexing agent mixed solution are placed in a reflux chamber, and the alkali solution is refluxed and melted, so that the aluminum precipitation reaction proceeds slowly, and during this reaction process , the alkali solution and nickel cobalt ions precipitate, and the complexing agent only acts on aluminum ions, so it can avoid the use of complexing agents to reduce the precipitation rate of nickel cobalt ions. The three transition metal elements in the prepared ternary cathode material are evenly distributed in the spherical particles, improving the lattice order of the material. The lithium nickel cobalt aluminate cathode material has a high tap density and a good discharge ratio. electrochemical properties such as capacity and cycle stability.

(2) The preparation method described in this disclosure is suitable for various ternary cathode materials. The first discharge capacity of the LiNi _0.8 Co _0.1 Mn _0.1 O ₂ cathode material can reach more than 203mAh/g, and the LiNi _0.75 Co _0.2 Mn _0.05 O can be obtained. ₂ The first discharge capacity of the cathode material can reach more than 190mAh/g, and the first discharge capacity of the LiNi _0.6 Co _0.3 Mn _0.1 O ₂ cathode material can reach more than 180mAh/g, and the retention rate can reach more than 96.8% after 100 cycles.

Other aspects will be apparent after reading and understanding the drawings and detailed description.

Description of the drawings

The accompanying drawings are used to provide a further understanding of the technical solutions herein, and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solutions herein, and do not constitute a limitation of the technical solutions herein.

Figure 1 is a schematic diagram of the device used in the preparation method of ternary cathode material according to an embodiment of the present disclosure, 1-freezing liquid C, 2-reflux device, 3-pump, 4-reaction device, 5-stirring rod, 6-alkali Sexual reflux liquid, 7-feeding port.

Figure 2 is an EDS diagram of the ternary cathode material prepared in Example 1 of the present disclosure.

Detailed ways

The technical solutions of the present disclosure will be further described below through specific implementations. Those skilled in the art should understand that the embodiments are only to help understand the present disclosure and should not be regarded as specific limitations of the present disclosure.

Example 1

This embodiment provides a ternary cathode material. The schematic diagram of the device used in the preparation method of the ternary cathode material is shown in Figure 1, where 1 is the freezing liquid C, 2 is the reflux device, 3 is the pump, and 4 is Reaction device, 5 is a stirring rod, 6 is an alkaline reflux liquid, and 7 is a feeding port. The preparation method includes the following steps:

(1) Mix nickel sulfate, cobalt sulfate and deionized water, freeze it in a spherical mold at -35°C for 8 hours to obtain a nickel concentration of 0.8mol/L, a cobalt concentration of 0.1mol/L, and a total metal concentration of 0.9mol/L. L of freezing liquid A, dissolve aluminum sulfate and acetylacetone in deionized water, and freeze at -35°C for 8 hours to obtain freezing liquid B with an aluminum ion concentration of 1 mol/L and an acetylacetone concentration of 0.2 mol/L. Frozen liquid A and frozen liquid B are crushed below -10°C, and then the smoothie-like (particle size <2mm) frozen liquid A and frozen liquid B are mixed evenly and pressed into a square or circular grinding tool with a pressure of 2MPa, and then Freeze at -40°C for 6 hours to obtain frozen liquid C. The ratio of nickel element, cobalt element and aluminum element in the frozen liquid C is 0.8:0.1:0.1;

(2) Use a sodium hydroxide solution with a pH of 11 as the reflux liquid, control the reflux liquid to reflux between the reflux device and the reaction device at a speed of 40 mL/min, and add a sodium hydroxide solution with a concentration of 6 mol/L to the feeding port. Control the pH in the system to 11, react at 50°C until all frozen liquid C is melted, then heat the entire mixed solution in the reactor to 60°C, and keep it warm for 10 hours to obtain a suspension;

(3) Separate the suspension, wash the precipitate three times with deionized water, and then dry it at 80°C to obtain nickel cobalt aluminum hydroxide. Combine nickel cobalt aluminum hydroxide and lithium hydroxide (Li/ M=1.02) was ground in ethanol using a ball mill, and calcined in two stages under an oxygen atmosphere. The first stage was at a temperature of 450°C and calcined for 6 hours, and the second stage was at a temperature of 800°C and calcined for 15 hours to obtain the ternary cathode material. The EDS diagram of the ternary cathode material is shown in Figure 2. It can be seen from Figure 2 that the three transition metal elements in the ternary cathode material produced by the method of the present disclosure are evenly distributed.

Example 2

This embodiment provides a ternary cathode material. The schematic diagram of the device used in the preparation method of the ternary cathode material is shown in Figure 1. The preparation method includes the following steps:

(1) Mix nickel sulfate, cobalt sulfate and deionized water, freeze it in a spherical mold at -30°C for 12 hours to obtain a nickel concentration of 0.75mol/L, a cobalt concentration of 0.2mol/L, and a total metal concentration of 0.95mol/L. L of freezing liquid A, dissolve aluminum sulfate and acetylacetone in deionized water, and freeze at -30°C for 12 hours to obtain freezing liquid B with an aluminum ion concentration of 0.5 mol/L and an acetylacetone concentration of 0.1 mol/L. Crush the freezing liquid A and freezing liquid B below -10°C, then mix the smoothie-like (particle size <2mm) freezing liquid A and freezing liquid B evenly and press it into a square or circular grinding tool with a pressure of 2MPa. Then freeze at -30°C for 12 hours to obtain frozen liquid C. The ratio of nickel element, cobalt element and aluminum element in the frozen liquid C is 0.75:0.2:0.05;

(2) Use a sodium hydroxide solution with a pH of 10.5 as the reflux liquid, control the reflux liquid to reflux between the reflux device and the reaction device at a speed of 10 mL/min, and add a sodium hydroxide solution with a concentration of 5 mol/L to the feeding port. Control the pH in the system to 10.5, react at 50°C until all frozen liquid C is melted, then heat the entire mixed solution in the reactor to 70°C, and keep it warm for 2 hours to obtain a suspension;

(3) Separate the suspension, wash the precipitate three times with deionized water, and then dry it at 80°C to obtain nickel cobalt aluminum hydroxide. Combine nickel cobalt aluminum hydroxide and lithium hydroxide (Li/ M=1.02) was ground in ethanol using a ball mill, and calcined in two stages under an oxygen atmosphere. The first stage was at a temperature of 300°C and calcined for 10 hours, and the second stage was at a temperature of 750°C and calcined for 20 hours to obtain the ternary cathode material.

Example 3

This embodiment provides a ternary cathode material. The schematic diagram of the device used in the preparation method of the ternary cathode material is shown in Figure 1. The preparation method includes the following steps:

(1) Mix nickel sulfate, cobalt sulfate and deionized water, freeze it in a spherical mold at -50°C for 5 hours to obtain a nickel concentration of 0.6mol/L, a cobalt concentration of 0.3mol/L, and a total metal concentration of 0.9mol/ L of freezing liquid A, dissolve aluminum sulfate and acetylacetone in deionized water, and freeze at -50°C for 5 hours to obtain freezing liquid B with an aluminum ion concentration of 1 mol/L and an acetylacetone concentration of 0.2 mol/L. Frozen liquid A and frozen liquid B are crushed below -10°C, and then the smoothie-like (particle size <2mm) frozen liquid A and frozen liquid B are mixed evenly and pressed into a square or circular grinding tool with a pressure of 2MPa, and then Freeze at -30°C for 12 hours to obtain frozen liquid C. The ratio of nickel element, cobalt element and aluminum element in the frozen liquid C is 0.6:0.3:0.1;

(2) Use a sodium hydroxide solution with a pH of 12 as the reflux liquid, control the reflux liquid to reflux between the reflux device and the reaction device at a speed of 200 mL/min, and add a sodium hydroxide solution with a concentration of 10 mol/L to the feeding port. Control the pH in the system to 12, react at 70°C until the frozen liquid C is completely melted, then keep the entire mixed solution in the reaction kettle insulated and aged for 2 hours to obtain a suspension;

(3) Separate the suspension, wash the precipitate three times with deionized water, and then dry it at 80°C to obtain nickel cobalt aluminum hydroxide. Combine nickel cobalt aluminum hydroxide and lithium hydroxide (Li/ M=1.02) was ground in ethanol using a ball mill and calcined in two stages under an oxygen atmosphere. The first stage was at a temperature of 650°C and calcined for 2 hours. The second stage was at a temperature of 850°C and calcined for 8 hours to obtain the ternary cathode material.

Example 4

The only difference between this embodiment and Example 1 is that the concentration of the complexing agent in the freezing liquid B in step (1) is 0.05 mol/L, and other conditions and parameters are exactly the same as in Example 1.

Example 5

The only difference between this embodiment and Example 1 is that the concentration of the complexing agent in the freezing liquid B in step (1) is 0.8 mol/L, and other conditions and parameters are exactly the same as in Example 1.

Example 6

The only difference between this example and Example 1 is that the reaction temperature in step (2) is 30°C, and other conditions and parameters are exactly the same as in Example 1.

Example 7

The only difference between this example and Example 1 is that the reaction temperature in step (2) is 80°C, and other conditions and parameters are exactly the same as in Example 1.

Comparative example 1

This comparative example provides a ternary cathode material. The preparation method of the ternary cathode material is as follows:

(1) Use nickel sulfate and cobalt sulfate to prepare solutions with a concentration of 2mol/L respectively, and prepare a 6mol/L sodium hydroxide solution. Add acetylacetone to the 0.2 mol/L aluminum sulfate solution so that the concentration of acetylacetone is 0.2 mol/L. Mix nickel sulfate and cobalt sulfate at a volume ratio of 8:1 to obtain a nickel-cobalt mixed solution;

(2) Mix the aluminum sulfate mixed solution, nickel and cobalt mixed solution and sodium hydroxide solution at a flow rate of 0.2L/h and 0.1L/h. At the same time, open the sodium hydroxide solution and adjust the flow rate of the sodium hydroxide solution to make the reactor system The pH is 11. Stop feeding after the solution fills the reaction kettle 60%, control the temperature to 60°C and react for 10 hours to obtain a suspension;

(3) Separate the suspension, wash the precipitate three times with deionized water, and then dry it at 80°C to obtain nickel cobalt aluminum hydroxide. Grind nickel cobalt aluminum hydroxide and lithium hydroxide in ethanol using a ball mill, and calcine in two stages under an oxygen atmosphere. The first stage is at a temperature of 450°C and calcined for 6 hours. The second stage is at a temperature of 800°C and calcined for 15 hours to obtain three Yuan cathode material.

Performance Testing:

The ternary cathode materials prepared in the Examples and Comparative Examples were made into 2032 button cells and performance tested at a current density of 0.1C and 3.0-4.3V. The test results are shown in Table 1:

Table 1

First discharge capacity (mAh/g) 100 cycles retention rate (%) Example 1 203.56 96.91 Example 2 190.83 96.85 Example 3 180.76 96.87 Example 4 185.34 94.17 Example 5 186.17 94.35 Example 6 187.63 95.01 Example 7 184.29 95.46 Comparative example 1 178.52 89.34

As can be seen from Table 1 and Examples 1-3, the preparation method described in the present disclosure is suitable for various ternary cathode materials, and the first discharge capacity of the prepared LiNi _0.8 Co _0.1 Mn _0.1 O ₂ cathode material can reach 203mAh. /g or more, the first discharge capacity of the LiNi _0.75 Co _0.2 Mn _0.05 O ₂ cathode material can reach more than 190mAh/g, and the first discharge capacity of the LiNi _0.6 Co _0.3 Mn _0.1 O ₂ cathode material can reach more than 180mAh/g. The retention rate can reach over 96.8% after 100 cycles.

It can be seen from the comparison between Example 1 and Examples 4-5 that during the preparation process of the ternary cathode material of the present disclosure, the concentration of the complexing agent in the freezing liquid B will affect its performance. The concentration of the complexing agent in the freezing liquid B will be If the concentration is controlled at 0.1~0.5mol/L, the performance of the cathode material will be better. If the concentration of the complexing agent is too high, the content of the complexing agent will be too high when the frozen liquid melts, which will cause the complexing agent to complex aluminum ions and fail. The difference in precipitation rates between nickel cobalt ions and aluminum ions is well regulated. If the concentration of the complexing agent is too low, the precipitation rate of nickel cobalt ions cannot be effectively reduced, making it difficult to uniformly precipitate nickel cobalt aluminum ions.

It can be seen from the comparison between Example 1 and Examples 6-7 that during the preparation process of the ternary cathode material of the present disclosure, the reaction temperature will affect its performance. The cathode material can be prepared by controlling the reaction temperature at 40-70°C. The performance is better. If the reaction temperature is too high, the melting rate is too fast, and it is difficult to ensure uniform precipitation of nickel, cobalt and aluminum. If the reaction temperature is too low, the reaction rate is too slow, and the core of the generated particles is too tight, making it difficult for lithium ions to enter. , affecting the gram capacity of the material.

From the comparison between Example 1 and Comparative Example 1, it can be seen that the present disclosure places the frozen Ni/Co mixed solution and the frozen Al ³⁺ complexing agent mixed solution in a reflux chamber, and the alkali solution is refluxed and melted, so that the aluminum precipitation reaction is slow. During this reaction, the alkali solution and nickel cobalt ions precipitate, and the complexing agent only acts on aluminum ions, so the use of complexing agents can be avoided to reduce the precipitation rate of nickel cobalt ions.

Claims (19)

1. A preparation method of ternary cathode material, the preparation method includes the following steps: (1) Mix the nickel source, cobalt source and solvent, freeze to obtain freezing liquid A, mix the aluminum source, complexing agent and solvent, adjust the pH and freeze to obtain freezing liquid B, crush freezing liquid A and freezing liquid B at low temperature , press and freeze to obtain freezing liquid C; (2) Place the frozen liquid C in a reflux device, control the alkaline reflux liquid to reflux between the reflux device and the reaction device, and control the temperature and pH in the system until the frozen liquid C is completely melted to obtain a suspension; (3) Perform solid-liquid separation treatment on the suspension, mix the obtained solid product with a lithium source, and sinter to obtain the ternary cathode material. 2. The preparation method according to claim 1, wherein the nickel source in step (1) includes any one or a combination of at least two of nickel sulfate, nickel nitrate, nickel chloride or nickel acetate. 3. The preparation method according to claim 1 or 2, wherein the cobalt source includes any one or a combination of at least two of cobalt sulfate, cobalt nitrate, cobalt chloride or cobalt acetate. 4. The preparation method according to any one of claims 1 to 3, wherein the concentration of the nickel source in the freezing liquid A is 0.1 to 1 mol/L. 5. The preparation method according to any one of claims 1 to 4, wherein the concentration of the cobalt source in the freezing liquid A is 0.1 to 1 mol/L. 6. The preparation method according to any one of claims 1 to 5, wherein the total concentration of the nickel source and the cobalt source in the freezing liquid A is 0.5-2 mol/L. 7. The preparation method according to any one of claims 1 to 6, wherein the aluminum source in step (1) includes any one or a combination of at least two of aluminum nitrate, aluminum sulfate or aluminum chloride. 8. The preparation method according to any one of claims 1 to 7, wherein the complexing agent includes any one or a combination of at least two of acetylacetone, oxalic acid, salicylic acid or sulfosalicylic acid . 9. The preparation method according to any one of claims 1 to 8, wherein the adjusting agent for adjusting pH includes sulfuric acid and/or hydrochloric acid. 10. The preparation method according to any one of claims 1-9, wherein the adjusted pH is 2-5. 11. The preparation method according to any one of claims 1 to 10, wherein the concentration of the aluminum source in the freezing liquid B is 0.1 to 1 mol/L. 12. The preparation method according to any one of claims 1 to 11, wherein the concentration of the complexing agent in the frozen liquid B is 0.1 to 0.5 mol/L. 13. The preparation method according to any one of claims 1 to 12, wherein the freezing temperature in step (1) is -30~-50°C; Optionally, the freezing time is 6 to 12 hours; Optionally, the temperature of the low-temperature crushing treatment is <-10°C; Optionally, the pressing pressure is 0.1 to 10 MPa; Optionally, the molar ratio of nickel element, cobalt element and aluminum element in the freezing liquid C is (0.6~0.9): (0.08~0.3): (0.02~0.1). 14. The preparation method according to any one of claims 1 to 13, wherein the alkaline reflux liquid in step (2) includes sodium hydroxide solution and/or potassium hydroxide solution; Optionally, the pH of the alkaline reflux liquid is 10.5-12; Optionally, the reflux speed of the alkaline reflux liquid is 10 to 200 mL/min. 15. The preparation method according to any one of claims 1 to 14, wherein the method of controlling the pH in the system in step (2) includes adding alkaline solution; Optionally, the pH in the control system is 10.5-12; Optionally, the concentration of the alkali solution is 5-10 mol/L; Optionally, the temperature in the system is 40-70°C; Optionally, the frozen liquid C is aged after all of it is melted; Optionally, the aging treatment time is 2 to 20 hours. 16. The preparation method according to any one of claims 1 to 15, wherein the lithium source in step (3) includes lithium hydroxide and/or lithium carbonate; Optionally, the total molar ratio of the lithium element in the lithium source and the metal element in the solid product is (1~1.1):1; Optionally, the sintering includes one-stage sintering and two-stage sintering; Optionally, the sintering temperature of the first section is 300-650°C; Optionally, the sintering time is 2 to 10 hours; Optionally, the temperature of the second-stage sintering is 700-850°C; Optionally, the second-stage sintering time is 8 to 20 hours. 17. A ternary cathode material, which is prepared by the method according to any one of claims 1 to 16. 18. A positive electrode piece, the positive electrode piece comprising the ternary positive electrode material according to claim 17. 19. A lithium ion battery, the lithium ion battery comprising the positive electrode plate according to claim 18.