WO2022127117A1 - Method for treating positive electrode material of waste lithium battery - Google Patents

Abstract

Disclosed in the present invention is a low-cost method for cleanly treating a positive electrode material of a waste lithium ion battery. The method comprises: performing high-temperature reduction on the pre-treated positive electrode material of a waste lithium ion battery, and grinding the reduced material, so as to obtain a reduction product having a particle size of < 200 μm; performing water leaching on the reduction product, and performing solid-liquid separation, so as to obtain a water leaching residue and a filtrate; performing magnetic sorting and separation on the water leaching residue, so as to obtain a magnetic nickel-cobalt alloy and a non-magnetic manganese oxide; and removing impurities from the filtrate, and evaporating and crystallizing the filtrate after removing impurities, so as to obtain a LiOH product. According to the present invention, the positive electrode material of the lithium ion battery is subjected to selective reduction by means of hydrogen, and a lithium element in the reduction product is easily dissolved into an aqueous solution; by means of one-time water leaching, the lithium leaching rate can reach 95% or more without multi-segment leaching, achieving the high recovery rate of the lithium element, and simplifying the process flow.

Description

[Title of invention formulated by ISA in accordance with Rule 37.2] Method for disposal of cathode materials for spent lithium batteries technical field

The invention belongs to the field of recycling waste lithium ion batteries, and in particular relates to a low-cost method for cleaning and processing positive electrode materials of waste lithium ion batteries.

Background technique

Lithium batteries have excellent physical and chemical properties such as high energy density, high voltage, fast charge and discharge speed, and good cycle stability. They are widely used in electronic technology products such as mobile phones and notebook computers, and have formed a huge market scale, especially for electric batteries. The development of automobiles has greatly increased the demand for lithium batteries. However, the life of lithium batteries is generally only 2 to 3 years. Some waste lithium batteries can be used in cascade, and those that cannot be used in cascade can only be scrapped. With the increase in the use of lithium batteries, the amount of scrapped batteries is also increasing. By 2020, the total number of scrapped lithium-ion batteries in the world will exceed 25 billion, weighing as much as 500,000 tons. Waste lithium-ion batteries contain a large amount of valuable valuable metals, such as nickel, cobalt, manganese, lithium, etc. Recycling waste lithium batteries can not only effectively alleviate the problem of resource shortage, but also avoid the toxic substances in waste lithium batteries. Pollution to the environment is of great significance to the sustainable development of the battery industry.

At present, the recycling methods of waste lithium battery cathode materials are established based on the technical principles of pyrometallurgy, hydrometallurgy, biometallurgy, etc., mainly including high temperature method, acid dissolution method and electrochemical dissolution method. The high temperature method is to remove other impurities in the positive electrode active material under the condition of high temperature, and then use magnetic separation, flotation and other methods to obtain various types of valuable metals, but the metal obtained by this method has a high impurity content, which requires further treatment. Only by purifying it can obtain higher purity metal materials, and this method has high cost and high energy consumption, which is not conducive to large-scale industrial production.

The acid-dissolving method refers to dissolving the positive electrode material with acid to obtain a metal ion solution, and then purifying the acid leaching solution by solvent extraction, precipitation, electrolysis, ion exchange, etc., and recovering valuable metal components. The acid-dissolving method has high recovery efficiency, but will produce a large amount of leachate, causing secondary pollution. In the acid-dissolving method, the solvent extraction method has good separation effect and low energy consumption, but the extraction agent is expensive and toxic, and the recovery and treatment process is complicated. The precipitation method is simple to operate and has a high recovery rate, but the purity of the product is not high. The products obtained by electrolysis are very pure, but consume a lot of electricity. The ion exchange method has high resource recovery rate and obvious impurity removal effect, but the operation process is complicated, which is not conducive to popularization and application.

The electrochemical dissolution method is to use the positive electrode material as the cathode and the lead as the anode in the electrolytic cell, and electrolytically decompose metal ions such as cobalt and nickel, and then recover them by extraction and other methods. This method is simple to operate, with high metal dissolution rate, but high power consumption.

Although the recycling of used lithium batteries can alleviate the crisis of resource shortage to a certain extent, there are still secondary pollution problems in the recycling process, and the cost of recycling is relatively high. According to foreign media reports, the cost of recycling lithium carbonate from used lithium batteries It is 5 times the current production cost of lithium carbonate. Therefore, there is an urgent need for a clean, environmentally friendly and low-cost method for recycling waste lithium batteries. The general components of cathode materials for waste lithium batteries are lithium iron phosphate, lithium manganate, lithium cobalt oxide, nickel-cobalt-manganese ternary materials, etc., so the ratio of nickel, cobalt, manganese, lithium and other metal elements in the cathode material during the recycling process are different, and even the proportion of the same ternary cathode material is very different. Therefore, it is difficult to reuse the cathode material, especially the composite cathode material.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background art, and to provide a low-cost method for cleaning and processing the positive electrode material of waste lithium ion batteries.

In order to solve the above-mentioned technical problems, the technical scheme proposed by the present invention is:

A low-cost method for cleaning and processing cathode materials of waste and used lithium ion batteries, comprising the following steps:

(1) The waste lithium-ion battery cathode material obtained after pretreatment is subjected to high-temperature reduction and grinding to obtain a reduction product with a particle size of <200 μm; magnetic separation at this particle size can achieve effective dissociation of magnetic particles and non-magnetic particles, and there are Conducive to the subsequent magnetic separation process;

(2) water immersion is carried out with the reduction product obtained in step (1), and solid-liquid separation is performed to obtain water leaching residue and filtrate;

(3) the water leaching slag obtained in step (2) is subjected to magnetic separation to obtain magnetic nickel-cobalt alloy and non-magnetic manganese oxide;

(4) removing impurities from the filtrate obtained in step (2), and performing evaporative crystallization on the filtrate after removing impurities to obtain LiOH product.

In the above method, preferably, in step (1), the temperature of the high-temperature reduction is 600°C to 900°C, the time is 0.5 to 3 hours, and the high-temperature reduction is performed in a hydrogen atmosphere.

In the above method, preferably, in step (2), the water immersion temperature is 30 to 90° C., the water immersion time is 0.5 to 3 hours, and the solid-liquid mass ratio during water immersion is 1:5 to 1:2. The solid-liquid mass ratio can ensure sufficient leaching of lithium element.

In the above-mentioned method, preferably, in step (3), the magnetic separation method is wet magnetic separation, and the magnetic field intensity during the magnetic separation separation is 50-300 mT.

In the above method, preferably, in step (4), the impurity removal is to first adjust the pH value of the filtrate to 7-12 to precipitate the impurity elements in the form of precipitation, and then perform solid-liquid separation.

In the above method, preferably, the pH of the filtrate is adjusted by adding ammonia water and/or ammonia gas.

In the above method, preferably, the positive electrode material of the lithium ion battery is a positive electrode material containing at least nickel, cobalt, manganese and lithium metal.

In the above method, preferably, the lithium ion battery positive electrode material includes lithium cobalt oxide, lithium manganate, lithium nickel cobalt oxide binary positive electrode material, lithium nickel manganate binary positive electrode material, and nickel cobalt lithium manganate ternary positive electrode material , A variety of mixtures of nickel cobalt lithium aluminate ternary positive electrode materials.

In the above method, in step (1), the pretreatment process of the positive electrode material of the waste lithium ion battery refers to that the battery is immersed in a NaCl solution to achieve deep discharge, and then battery components such as positive electrode sheets and negative electrode sheets are obtained by disassembling, and finally the positive electrode is processed at high temperature. The binder was removed from the sheet to obtain a positive electrode material powder.

Compared with the prior art, the advantages of the present invention are:

(1) The present invention uses hydrogen to selectively reduce the positive electrode material of the lithium ion battery, and the lithium element in the reduction product is easily dissolved into the aqueous solution. Through one water immersion, the lithium leaching rate can reach more than 95%, and multi-stage leaching is not required. The high recovery rate of lithium element simplifies the process flow.

(2) The present invention obtains non-magnetic substances such as magnetic nickel-cobalt alloy and manganese oxide after water immersion of the hydrogen reduction product, avoiding the use of reducing agents such as hydrogen peroxide in the wet process, the reduction effect is good, and the reaction is clean and pollution-free. Other impurities will be introduced, and the product has high purity.

(3) The present invention uses hydrogen to selectively reduce the positive electrode material of the lithium ion battery, and the nickel-cobalt alloy particles in the reduction product and the non-magnetic oxide are easily dissociated, and the nickel-cobalt alloy and the non-magnetic material can be realized by grinding. The high-efficiency dissociation of nickel, cobalt and manganese realizes the separation and recovery of valuable metals, and at the same time, grinding increases the specific surface area of the reduction product and improves the leaching rate of lithium in the subsequent water leaching process.

(4) The present invention conducts magnetic separation of water leaching slag, makes full use of the physical properties of the separated components themselves, realizes the efficient separation of nickel-cobalt and manganese, is simple to operate, does not need any addition of chemical reagents, and has remarkable separation and recovery effects.

(5) The processing method of the present invention has strong raw material adaptability, and can process various positive electrode materials of lithium ion batteries.

(6) The processing method of the present invention is low in cost, clean and pollution-free, and the process is short and easy to implement, which provides a reliable technical guarantee for the large-scale clean recovery and utilization of valuable metals of lithium batteries.

In summary, the present invention utilizes the high reducibility of hydrogen to selectively reduce nickel and cobalt elements at a specific temperature to form a nickel-cobalt alloy, and the lithium element is transformed into a state that is easily hydrolyzed during the hydrogen reduction process. The LiOH product is obtained by evaporation and crystallization, and the efficient separation of lithium is realized. The solid components enter the water leaching slag, and the magnetic difference between the nickel-cobalt alloy and other components is fully utilized, and the magnetic part rich in nickel-cobalt alloy and The non-magnetic part rich in manganese oxide realizes the efficient separation and recovery of nickel, cobalt and manganese, and the whole process is simple, does not produce secondary pollution, and does not produce greenhouse gases such as carbon dioxide.

Description of drawings

FIG. 1 is a flow chart of processing a cathode material of a waste lithium ion battery according to an embodiment of the present invention.

FIG. 2 is the SEM and mapping images of the product obtained after the cathode material of the waste lithium ion battery is reduced by hydrogen in Example 5 of the present invention.

3 is a SEM and mapping diagram of a magnetic product obtained after magnetic separation of the positive electrode material of a waste lithium ion battery in Example 5 of the present invention.

Detailed ways

In order to facilitate understanding of the present invention, the present invention will be described more comprehensively and in detail below with reference to the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present invention is not limited to the following specific embodiments.

Unless otherwise defined, all technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used in this document are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or can be prepared by existing methods.

Example 1:

A low-cost cleaning method of the present invention for the positive electrode material of waste lithium ion batteries, the process flow chart is shown in Figure 1, and includes the following steps:

(1) Dry the waste lithium battery positive electrode material (a mixture of nickel-cobalt lithium manganate composite positive electrode material and nickel-cobalt lithium manganate composite positive electrode material) obtained after the pretreatment, and then put it into a reduction furnace, under an argon protective atmosphere The reduction was carried out by introducing hydrogen (the flow rate of hydrogen was 100ml/min), the reduction temperature was 600°C, and the reduction time was 0.5h.

(2) Putting the reduction product obtained in step (1) into a ball mill for ball milling to obtain a reduction product powder with a particle size of 1-200 μm.

(3) The reduction product powder obtained in step (2) is immersed in water, the temperature is 50° C., the water immersion time is 1 h, and the water immersion solid-liquid mass ratio is 1:3, and the lithium element can be enriched by water immersion to In the water leaching solution, filter to obtain water leaching residue and filtrate.

(4) the water leaching slag obtained in step (3) is subjected to wet magnetic separation, the magnetic field intensity is 100mT, and the nickel-cobalt enters the magnetic part in an alloy state (the magnetic part is a nickel-cobalt alloy, and the detected Co content is 8.96%, The content of Ni is 90.12%, the content of Mn is 0.32%), the manganese element enters the non-magnetic part in the form of oxide (the non-magnetic part is crude manganese oxide, the content of Mn is 72.38%, the content of Ni is 0.52%, The Co content was 0.35%, and the Li content was 2.28%).

(5) adding ammonia water to the filtrate obtained in step (3) to make the pH value of the solution 7, so that impurity elements are precipitated in the form of precipitation, and then the impurities are removed by filtration separation, and the filtrate after removal of impurities is evaporated and crystallized to obtain LiOH product.

After calculation, in this example, the recovery rate of Co element is 99.56%, the recovery rate of Ni element is 99.62%, the recovery rate of manganese is 90.32%, and the recovery rate of Li element is 95.07%.

Example 2:

A low-cost cleaning method of the present invention for the positive electrode material of waste lithium ion batteries, the process flow chart is shown in Figure 1, and includes the following steps:

(1) drying the waste lithium battery positive electrode material (a mixture of lithium manganate positive electrode material and nickel-cobalt aluminate composite positive electrode material) obtained after pretreatment, and putting the dried waste and old lithium ion battery positive electrode material into a reduction furnace , under the protective atmosphere of argon gas, hydrogen was introduced for reduction (the hydrogen flow rate was 100ml/min), the reduction temperature was 700°C, and the reduction time was 1h.

(2) Putting the reduction product obtained in step (1) into a ball mill for ball milling to obtain a reduction product powder with a particle size of 1-200 μm.

(3) The reduction product powder obtained in step (2) is immersed in water, the water immersion temperature is 60° C., the water immersion time is 0.5h, the water immersion solid-liquid mass ratio is 1:4, and the lithium element is enriched by water immersion. Collected in water leaching solution, filtered to obtain water leaching residue and filtrate.

(4) The water leaching slag obtained in step (3) is subjected to wet magnetic separation, the magnetic field intensity is 50mT, nickel and cobalt enter the magnetic part in an alloy state, and manganese element enters the non-magnetic part in the form of oxide. The magnetic part is a nickel-cobalt alloy, the content of Co is 11.98%, the content of Ni is 87.28%, and the content of Mn is 0.25%. The non-magnetic part is crude manganese oxide, the content of Mn is 49.26%, the content of Ni is 0.23%, the content of Co is 0.39%, the content of Al is 7.88%, and the content of Li is 0.98%.

(5) adding ammonia water to the filtrate obtained in step (3) to make the solution pH 7, so that impurity elements such as aluminum are precipitated in the form of precipitation, and then the impurities are removed by filtration separation, and the filtrate after removing the impurities is evaporated and crystallized to obtain LiOH products .

After calculation, in this example, the recovery rate of Co element is 99.72%, the recovery rate of Ni element is 99.88%, the recovery rate of manganese is 94.36%, and the recovery rate of Li element is 98.26%.

Example 3:

A low-cost method for cleaning and processing waste lithium-ion battery positive electrode materials of the present invention, the process flow chart of which is shown in Figure 1, and the method includes the following steps:

(1) drying the waste lithium battery positive electrode material (the mixture of lithium cobalt oxide positive electrode material and nickel cobalt lithium manganate positive electrode material) obtained after the pretreatment, and putting the dried waste and old lithium ion battery positive electrode material into the reduction furnace, Under the protective atmosphere of argon gas, hydrogen was introduced for reduction (the flow rate of hydrogen gas was 100 ml/min), the reduction temperature was 800 °C, and the reduction time of hydrogen was 2 h.

(2) Putting the reduction product obtained in step (1) into a ball mill for ball milling to obtain a reduction product powder with a particle size of 1-200 μm.

(3) The reduction product powder obtained in step (2) is immersed in water, the water immersion temperature is 70° C., the water immersion time is 2 hours, the water immersion solid-liquid mass ratio is 1:5, and the lithium element is enriched by water immersion into the water leaching solution and filtering to obtain water leaching residue and filtrate.

(4) the water leaching slag obtained in step (3) is subjected to wet magnetic separation, the magnetic field intensity is 200mT, and the nickel-cobalt enters the magnetic part in an alloy state (after testing, the content of Co in the magnetic part is 32.88%, the content of Ni is 66.56%, the content of Mn is 0.28%), manganese element enters the non-magnetic part in the form of oxide (after testing, the content of Mn in this part is 72.03%, the content of Ni is 0.25%, the content of Co is 0.32%, Li content of 2.36%).

(5) Ammonia water is added to the filtrate obtained in step (3) to make the pH value of the solution 8, so that impurity elements are precipitated in the form of precipitation, and then impurities are removed by filtration separation, and the filtrate after removing impurities is evaporated and crystallized to obtain LiOH product.

After calculation, in this example, the recovery rate of Co element is 99.52%, the recovery rate of Ni element is 99.83%, the recovery rate of manganese is 92.96%, and the recovery rate of Li element is 95.91%.

Embodiment 4:

A low-cost method for cleaning and processing waste lithium-ion battery positive electrode materials of the present invention, the process flow chart of which is shown in Figure 1, and the method includes the following steps:

(1) drying the waste lithium battery positive electrode material (a mixture of nickel cobalt lithium manganate positive electrode material and nickel cobalt lithium aluminate positive electrode material) obtained after pretreatment, and putting the dried waste and old lithium ion battery positive electrode material into a reduction furnace In the argon protective atmosphere, hydrogen was introduced for reduction (the hydrogen flow rate was 100 ml/min), the reduction temperature was 900 °C, and the hydrogen reduction time was 3 h.

(2) Putting the reduction product obtained in step (1) into a ball mill for ball milling to obtain a reduction product powder with a particle size of 1-200 μm.

(3) immersing the reduction product powder obtained in step (2), the immersion temperature is 80° C., the immersion time is 3h, the solid-liquid mass ratio of the immersion is 1:3, and the lithium element is enriched by the immersion. into the water leaching solution and filtering to obtain water leaching residue and filtrate.

(4) the water leaching slag obtained in step (3) is subjected to wet magnetic separation, the magnetic field intensity is 300mT, and the nickel and cobalt enter the magnetic part in an alloy state (after testing, the content of Co in the magnetic part is 12.18%, the content of Ni is 87.07%, the content of Mn is 0.35%), manganese element enters the non-magnetic part in the form of oxide (after testing, the content of Mn in this part is 44.9%, the content of Ni is 0.32%, the content of Co is 0.66%, and the content of Al The content of Li is 12.38%, and the content of Li is 2.11%).

(5) adding ammonia water to the filtrate obtained in step (3) to make the pH value of the solution 9, so that impurity elements such as aluminum are precipitated in the form of precipitation, and then the impurities are removed by filtration separation, and the filtrate after removing the impurities is evaporated and crystallized to obtain LiOH products.

After calculation, in this example, the recovery rate of Co element is 99.48%, the recovery rate of Ni element is 99.72%, the recovery rate of manganese is 90.21%, and the recovery rate of Li element is 96.32%.

Example 5:

A low-cost method for cleaning and processing waste lithium-ion battery positive electrode materials of the present invention, the process flow chart of which is shown in Figure 1, and the method includes the following steps:

(1) drying the waste lithium battery positive electrode material (a mixture of nickel cobalt lithium manganate positive electrode material and nickel cobalt lithium aluminate positive electrode material) obtained after pretreatment, and putting the dried waste and old lithium ion battery positive electrode material into a reduction furnace In the argon protective atmosphere, hydrogen was introduced for reduction (the hydrogen flow rate was 100ml/min), the reduction temperature was 750°C, and the hydrogen reduction time was 1h. The elemental composition analysis is shown in Table 1.

Table 1 Metal element composition of reduction products

element	Mass content %
Ni	63.26
Co	9.68
Mn	4.39
Al	3.03
Li	7.31
O	12.33

(2) Putting the reduction product obtained in step (1) into a ball mill for ball milling to obtain a reduction product powder with a particle size of 1-200 μm.

(3) immersing the reduction product powder obtained in step (2) with water immersion temperature of 50° C., water immersion time of 1 h, and water immersion solid-liquid mass ratio of 1:2, and enriching lithium element by water immersion into the water leaching solution and filtering to obtain water leaching residue and filtrate.

(4) The water leaching slag obtained in step (3) is subjected to wet magnetic separation, the magnetic field intensity is 100mT, and nickel and cobalt enter the magnetic part in an alloy state. The SEM photo and mapping diagram of the magnetic part product are shown in Figure 3. Detection, element composition analysis is shown in Table 2, the content of Co in the magnetic part is 12.58%, the content of Ni is 86.03%, the content of Mn is 0.48%, the manganese element enters the non-magnetic part in the form of oxide, and its metal element composition The composition is shown in Table 3. The content of Mn in this part is 38.22%, the content of Ni is 0.55%, the content of Co is 0.29%, the content of Al is 18.77%, and the content of Li is 4.79%.

Table 2 Elemental composition of magnetic products

element	Mass content %
Ni	86.03
Co	12.58
Mn	0.48
Al	0.30
Li	0.07
O	0.54

Table 3 Elemental composition of non-magnetic products

element	Mass content %
Ni	0.55
Co	0.29
Mn	38.22
Al	18.77
Li	4.79
O	37.38

(5) Ammonia water is added to the filtrate obtained in step (3) to make the solution pH 12, so that impurity elements such as aluminum are precipitated in the form of precipitation, and then impurities are removed by filtration separation, and the filtrate after removing impurities is evaporated and crystallized to obtain LiOH product.

After calculation, in this example, the recovery rate of Co element is 99.78%, the recovery rate of Ni element is 99.66%, the recovery rate of manganese is 88.94%, and the recovery rate of Li element is 95.68%.

Example 6:

A low-cost method for cleaning and processing waste lithium-ion battery positive electrode materials of the present invention, the process flow chart of which is shown in Figure 1, and the method includes the following steps:

(1) drying the waste lithium battery positive electrode material (a mixture of nickel cobalt oxide lithium positive electrode material, nickel manganate lithium positive electrode material and nickel cobalt aluminum aluminate positive electrode material) obtained after pretreatment, and drying the waste and old lithium ion battery after drying The positive electrode material was placed in a reduction furnace, and hydrogen was introduced into the reduction furnace under an argon protective atmosphere (the hydrogen flow rate was 100 ml/min), the reduction temperature was 900 °C, and the hydrogen reduction time was 2 h.

(2) Putting the reduction product obtained in step (1) into a ball mill for ball milling to obtain a reduction product powder with a particle size of 1-200 μm.

(3) The reduction product powder obtained in the step (2) is subjected to water immersion, the water immersion temperature is 90° C., the water immersion time is 2h, the water immersion solid-liquid mass ratio is 1:3, and the lithium element is enriched by water immersion into the water leaching solution and filtering to obtain water leaching residue and filtrate.

(4) the water leaching slag obtained in step (3) is subjected to wet magnetic separation, the magnetic field intensity is 100mT, and nickel and cobalt enter the magnetic part in an alloy state (after testing, the content of Co in the magnetic part is 11.23%, the content of Ni is 87.96%, the content of Mn is 0.33%), manganese element enters the non-magnetic part in the form of oxide (the content of Mn in this part is 46.77%, the content of Ni is 0.35%, the content of Co is 0.58%, and the content of Al is 0.58%. The content of Li is 10.28%, and the content of Li is 1.22%).

(5) Ammonia water is added to the filtrate obtained in step (3) to make the pH value of the solution 10, so that impurity elements are precipitated in the form of precipitation, and then impurities are removed by filtration separation, and the filtrate after removing impurities is evaporated and crystallized to obtain LiOH product.

After calculation, in this example, the recovery rate of Co element is 99.76%, the recovery rate of Ni element is 99.55%, the recovery rate of manganese is 90.02%, and the recovery rate of Li element is 97.64%.

Claims (8)

1. A low-cost method for cleaning and processing positive electrode materials of waste lithium-ion batteries, characterized in that it comprises the following steps:

   (1) The waste lithium-ion battery cathode material obtained after pretreatment is subjected to high temperature reduction and grinding to obtain a reduction product with a particle size of <200 μm;

   (2) water immersion is carried out with the reduction product obtained in step (1), and solid-liquid separation is performed to obtain water leaching residue and filtrate;

   (3) the water leaching slag obtained in step (2) is subjected to magnetic separation to obtain magnetic nickel-cobalt alloy and non-magnetic manganese oxide;

   (4) removing impurities from the filtrate obtained in step (2), and performing evaporative crystallization on the filtrate after removing impurities to obtain LiOH product.
2. The method of claim 1, wherein, in step (1), the temperature of the high-temperature reduction is 600°C to 900°C, and the time is 0.5 to 3 hours, and the high-temperature reduction is performed in a hydrogen atmosphere.
3. The method of claim 1, wherein in step (2), the water immersion temperature is 30-90° C., the water immersion time is 0.5-3h, and the solid-liquid mass ratio during water immersion is 1:5 ~1:2.
4. The method according to claim 1, characterized in that, in step (3), the magnetic separation method is wet magnetic separation, and the magnetic field strength is 50-300 mT during magnetic separation.
5. The method according to any one of claims 1 to 4, wherein, in step (4), the impurity removal is to first adjust the pH value of the filtrate to 7 to 12 so that the impurity elements are precipitated in the form of precipitation, and then carry out Solid-liquid separation.
6. The method of claim 5, wherein the pH of the filtrate is adjusted by adding ammonia water and/or ammonia gas.
7. The method according to any one of claims 1 to 4, wherein the positive electrode material of the lithium ion battery is a positive electrode material containing at least nickel, cobalt, manganese and lithium metal.
8. The method of claim 7, wherein the lithium ion battery positive electrode materials are lithium cobalt oxide, lithium manganate, lithium nickel cobalt oxide binary positive electrode material, lithium nickel manganate binary positive electrode material, nickel cobalt manganese acid A mixture of lithium ternary cathode materials and nickel cobalt lithium aluminate ternary cathode materials.

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