WO2022142904A1

WO2022142904A1 - Method for regenerating ternary precursor by using nickel-cobalt-manganese residue

Info

Publication number: WO2022142904A1
Application number: PCT/CN2021/133163
Authority: WO
Inventors: 郭春平; 刘雯雯; 周有池; 文小强; 洪侃; 赖华生; 黄叶钿; 普建; 张帆; 吴世勇
Original assignee: 赣州有色冶金研究所有限公司
Priority date: 2021-01-04
Filing date: 2021-11-25
Publication date: 2022-07-07
Also published as: CN112830526B; CN112830526A

Abstract

A method for regenerating a ternary precursor by using a nickel-cobalt-manganese residue, comprising: mixing a nickel-cobalt-manganese residue, water, and a reducing agent, adjusting the obtained mixed solution to alkaline, and then mixing same with an ammonium salt to obtain a mixed slurry; and carrying out a hydrothermal reaction on the mixed slurry to obtain a ternary precursor. The nickel-cobalt-manganese residue and the reducing agent are mixed for a hydrothermal reaction; under the action of the reducing agent, a metal oxide in the nickel-cobalt-manganese residue is reduced to a corresponding +2-valent metal hydroxide or carbonate; the morphology and particle size of the product are controlled by adjusting the pH value, adding an ammonium salt, and controlling the hydrothermal reaction temperature; finally, the obtained product can restore the morphology and electrochemical performance of the original ternary precursor. The method for regenerating a ternary precursor by using a nickel-cobalt-manganese residue allows for direct reduction of a nickel-cobalt-manganese residue into a ternary precursor, can implement recycling of waste ternary positive electrode materials, and has a great application prospect.

Description

A method for regenerating ternary precursors using nickel-cobalt-manganese slag

This application claims the priority of the Chinese patent application with the application number 202110002935.3 and the invention titled "Method for Regenerating Ternary Precursors Using Nickel-Cobalt-Manganese Slag", which was submitted to the China Patent Office on January 4, 2021, the entire contents of which are by reference Incorporated in this application.

technical field

The invention relates to the technical field of recycling waste ternary positive electrode materials, in particular to a method for regenerating ternary precursors by using nickel cobalt manganese slag.

Background technique

Nickel-cobalt lithium manganate ternary cathode material (NCM) has the advantages of high energy density, relatively low cost, and excellent cycle performance, and is the most promising cathode material currently in mass production. In the future, as the production and sales of new energy vehicles continue to rise, the continuous expansion of ternary battery production will drive the further expansion of the ternary cathode material market.

After the lithium-ion battery has been charged and discharged for many times, the battery structure will change, causing the lithium-ion battery to fail and be scrapped. The production and use of a large number of lithium-ion batteries will inevitably lead to the explosive generation of waste lithium-ion batteries. According to the scrapped amount of power lithium batteries used in commercial vehicles (3-year battery life) and passenger cars (5-year battery life), with the sharp increase in the production and sales of new energy vehicles, the peak of power battery retirement will also follow. According to the report of the Prospective Industry Research Institute, only the value of metal elements in the dismantling and recycling of waste power batteries is estimated, and the market size of China's power battery recycling market has exceeded 5 billion yuan. billions of dollars.

At present, waste NCM is generally treated and recovered by the method of high acid and total dissolution. Ni, Co and Mn in NCM exist in the valence of +2, +3 and +4 respectively, and there are also a small amount of Ni(III) and Mn(III) . In order to convert high-valence Co(III), Mn(III), Ni(III) and Mn(IV) into low-valence Co(II), Mn(II) and Ni(II) which are more easily leached by acid , usually add an appropriate amount of reducing agent, and convert NCM into a leaching solution containing Ni, Co, Mn, and Li by using a high-acid full-dissolving method. This method involves high-acid dissolution and chemical precipitation or extraction processes. The environmental protection pressure is high, the process flow is long, and additional waste will be generated, causing secondary pollution.

Patent CN110835117A discloses a method for selectively extracting lithium from waste ternary positive electrode materials, wherein lithium is extracted into water by means of roasting, water immersion, etc., to obtain a lithium-rich solution, and the remaining waste residue is nickel-cobalt-manganese residue. There is no description of how the remaining nickel-cobalt-manganese slag should be further treated.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a method for regenerating ternary precursors from nickel-cobalt-manganese slag. The method provided by the invention can directly regenerate the ternary precursor by utilizing the nickel-cobalt-manganese slag remaining after the selective lithium extraction of the ternary cathode material, and the regenerated ternary precursor can restore the morphology and electrochemical performance of the original ternary precursor .

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

A method for utilizing nickel-cobalt-manganese slag to regenerate ternary precursor, comprising the following steps:

Mixing nickel-cobalt-manganese slag, water and a reducing agent, adjusting the obtained mixture to alkaline, and then mixing with ammonium salt to obtain a mixed slurry; the nickel-cobalt-manganese slag is selected from waste nickel-cobalt-manganate lithium ternary positive electrode material The residual residue after lithium extraction;

The mixed slurry is subjected to a hydrothermal reaction to obtain a ternary precursor; the hydrothermal reaction includes a heating stage and a heat preservation stage that are performed in sequence, and the temperature of the heat preservation stage is 250-380°C.

Preferably, the components in the mixed slurry further include a nickel source, a cobalt source and a manganese source.

Preferably, the nickel source is nickel sulfate, the cobalt source is cobalt sulfate, and the manganese source is manganese sulfate.

Preferably, the reducing agent includes one or more of sulfide, sulfite, thiosulfate, hydrazine, hydroxylamine and aldehyde.

Preferably, the sulfide includes one or more of sodium sulfide, potassium sulfide, ammonium sulfide, zinc sulfide and hydrogen sulfide; the sulfite includes sodium sulfite, ammonium sulfite, potassium sulfite, zinc sulfite and One or more of sodium bisulfite; the thiosulfate includes one or more of sodium thiosulfate, ammonium thiosulfate and potassium thiosulfate.

Preferably, the mass of the reducing agent is 8-40% of the mass of the nickel-cobalt-manganese slag.

Preferably, the reagents used to adjust the mixture to be alkaline include one or more of ammonia water, sodium hydroxide, sodium carbonate, potassium hydroxide and urea; the pH value of the mixture is adjusted to 8.5-12.

Preferably, the ammonium salt includes one or more of ammonium carbonate, ammonium bicarbonate and ammonium oxalate.

Preferably, the mass of the ammonium salt is 10-80% of the mass of the nickel-cobalt-manganese slag.

Preferably, the holding time is 2 to 6 hours, and the pressure is 5 to 15 MPa.

Preferably, the heating stage includes a first stage and a second stage that are carried out in sequence, the first stage is heated from room temperature to 200°C, the heating rate is 1.5-3°C/min, and the second stage is heated from 200°C To the temperature in the holding stage, the heating rate is 0.4-1.3°C/min.

Preferably, the waste nickel cobalt lithium manganate ternary positive electrode material includes NCM523 or NCM622.

The invention provides a method for regenerating a ternary precursor by utilizing nickel-cobalt-manganese slag, comprising the following steps: mixing nickel-cobalt-manganese slag, water and a reducing agent, adjusting the obtained mixture to alkaline, and then mixing with ammonium salt to obtain a mixed slurry; the nickel-cobalt-manganese slag is the waste residue remaining after the selective extraction of lithium from the waste nickel-cobalt lithium manganate ternary positive electrode material; the mixed slurry is subjected to a hydrothermal reaction to obtain a ternary precursor; The hydrothermal reaction includes a heating stage and a heat preservation stage in sequence, and the temperature of the heat preservation stage is 250-380°C. In the invention, the nickel-cobalt-manganese slag is mixed with a reducing agent to carry out a hydrothermal reaction, and under the action of the reducing agent, the high-valent metals in the nickel-cobalt-manganese slag are reduced to +2 valence, and the product is reduced by adding ammonium salt and controlling the hydrothermal reaction temperature. The morphology and particle size of the obtained product can be controlled to restore the morphology and electrochemical performance of the original ternary precursor.

The method provided by the invention uses the nickel-cobalt-manganese slag remaining after the selective extraction of lithium from the waste nickel-cobalt lithium manganate ternary positive electrode material as the raw material to directly regenerate the ternary precursor, and the whole process does not require purification, impurity removal and extraction separation, and the technological process is short. , the cost is low, and there is no need to use high acid to dissolve the nickel-cobalt-manganese slag, which solves the problems of large acid-base consumption and high environmental protection pressure in the traditional high-acid full-dissolving method; the method provided by the invention can realize the waste ternary positive electrode material. Recycling, reducing my country's external dependence on cobalt, nickel and lithium resources, and stabilizing the price of cobalt resources, which continue to grow rapidly in downstream demand, are conducive to promoting the sustainable and healthy development of my country's new energy vehicles and have great application prospects.

In addition, the traditional method of synthesizing ternary precursors uses metal salts as raw materials, and prepares ternary precursors through the reaction of metal ions and OH ^- or CO ₃ ^2- . In the reaction process, a large amount of ammonia water or carbonate is required, and the cost is relatively high. High, the method provided by the present invention uses nickel-cobalt-manganese slag as raw material, nickel, cobalt and manganese elements in the nickel-cobalt-manganese slag exist in the form of oxides, and the oxides of nickel-cobalt-manganese undergo a reduction reaction under alkaline conditions, and the required The amount of OH ^- is less, so the cost of preparing the ternary precursor is lower, a lot of ammonia water is saved, and the pressure on environmental protection is relieved.

Further, the medicaments used in the present invention are all common and low-cost chemical raw materials in the industry, and the cost of regenerating the ternary precursor is lower.

The results of the examples show that the morphology and particle size of the ternary precursors regenerated by the method of the present invention are similar to the original ternary precursors, and the ternary cathode materials prepared by using the regenerated ternary precursors have high discharge specific capacity and charge-discharge cycles. Good performance.

Description of drawings

Fig. 1 is the schematic flow chart of regeneration ternary precursor in the embodiment of the present invention;

Fig. 2 is the XRD pattern of nickel-cobalt-manganese slag;

Fig. 3 is the SEM image of nickel-cobalt-manganese slag;

Fig. 4 is the XRD pattern of the nickel-cobalt lithium manganate ternary positive electrode material obtained by lithium calcination in Example 1;

Fig. 5 is the SEM image of the nickel-cobalt lithium manganate ternary positive electrode material obtained by lithium calcination in Example 1;

Fig. 6 is the SEM image of the ternary precursor obtained in Example 1;

Fig. 7 is the SEM image of the ternary precursor obtained in Example 2;

Fig. 8 is the SEM image of the ternary precursor obtained in Example 3;

Fig. 9 is the SEM image of the ternary precursor obtained in Example 4;

Figure 10 is the SEM image of the hydrothermal product obtained in Comparative Example 1;

Figure 11 is the SEM image of the hydrothermal product obtained in Comparative Example 2;

FIG. 12 is a SEM image of the hydrothermal product obtained in Comparative Example 3. FIG.

Detailed ways

The invention provides a method for utilizing nickel-cobalt-manganese slag to regenerate ternary precursor, comprising the following steps:

In the present invention, the nickel-cobalt-manganese slag is the waste residue remaining after the selective extraction of lithium from the waste nickel-cobalt lithium manganate ternary positive electrode material; the main elements contained in the nickel-cobalt-manganese slag are nickel, cobalt, manganese, oxygen , in which Ni, Co, and Mn exist in valences of +2, +3, and +4, respectively. The present invention does not have special requirements on the type of the nickel-cobalt lithium manganate ternary positive electrode material, and any common waste nickel-cobalt lithium manganate ternary positive electrode material in the art can be used, such as NCM523 and NCM622. In a specific embodiment of the present invention, the selective lithium extraction is preferably carried out according to the method disclosed in CN110835117A, and the specific steps are as follows:

Mixing waste ternary positive electrode material powder with acid, and performing one-stage roasting to obtain a one-stage roasting product;

Mix one-stage roasting product with auxiliary agent, carry out two-stage roasting, obtain two-stage roasting product;

The second-stage roasting product is put into water for leaching and solid-liquid separation to obtain a lithium-rich solution.

Wherein, the solid material obtained after solid-liquid separation is rich in a large amount of cobalt, nickel and manganese metal elements, which is the nickel-cobalt-manganese slag of the present invention.

In the present invention, nickel-cobalt-manganese slag, water and reducing agent are mixed, the obtained mixture is adjusted to be alkaline, and then mixed with ammonium salt to obtain mixed slurry. In the present invention, the water is preferably deionized water; the reducing agent preferably includes one or more of sulfide, sulfite, thiosulfate, hydrazine, hydroxylamine and aldehyde; the sulfide is preferably Including one or more of sodium sulfide, potassium sulfide, ammonium sulfide, zinc sulfide and hydrogen sulfide; the sulfite preferably includes sodium sulfite, ammonium sulfite, potassium sulfite, zinc sulfite and sodium bisulfite. One or more; the thiosulfate preferably includes one or more of sodium thiosulfate, ammonium thiosulfate and potassium thiosulfate; the present invention does not have special requirements for the type of the aldehyde, using this Any aldehydes with reducing properties that are well known to those skilled in the art can be used, such as formaldehyde. In the present invention, the mass of the reducing agent is preferably 8-40% of the mass of the nickel-cobalt-manganese slag, more preferably 10-35%.

The present invention has no special requirements on the mixing mode of the nickel-cobalt-manganese slag, water and the reducing agent, as long as uniform mixing can be achieved. In the present invention, the mixture of nickel-cobalt-manganese slag, water and reducing agent is uniformly stirred and adjusted to be alkaline, preferably adjusted to a pH value of 8.5-12, more preferably adjusted to a pH value of 9-11; in the present invention, the The reagent used to adjust the mixture to alkalinity is preferably one or more of ammonia water, sodium hydroxide, sodium carbonate, potassium hydroxide and urea; the present invention adjusts the mixture to alkalinity, which can ensure that ^OH- With a certain concentration, it is conducive to the complete precipitation of supplementary elements.

In the present invention, the ammonium salt preferably includes one or more of ammonium carbonate, ammonium bicarbonate and ammonium oxalate; the quality of the ammonium salt is preferably 10-80% of the quality of the nickel-cobalt-manganese slag, and more It is preferably 15-40%; the ammonium salt provides ammonium ions, which can control the morphology of the product and improve the sphericity of the product.

In the present invention, the components in the mixed slurry preferably further include a nickel source, a cobalt source and a manganese source; the nickel source is preferably nickel sulfate, the cobalt source is preferably cobalt sulfate, and the manganese source is preferably For manganese sulfate, the present invention supplements the trace amounts of nickel, cobalt and manganese lost in the process of selective extraction of lithium by adding nickel source, cobalt source and manganese source to the waste nickel-cobalt lithium manganate ternary positive electrode material. The present invention is preferably based on waste nickel-cobalt-manganese. The type of lithium oxide ternary cathode material controls the amount of nickel source, cobalt source and manganese source added. For example, the waste nickel cobalt lithium manganate ternary cathode material is NCM523 (that is, the molar ratio of nickel element, cobalt element and manganese element is 5:2:3), the present invention makes the molar ratio of nickel element, cobalt element and manganese element in the mixture of nickel-cobalt-manganese slag, nickel source, cobalt source and manganese source by adding nickel source, cobalt source and manganese source to be: 5:2:3; in the specific embodiment of the present invention, it is preferable to first detect the nickel, cobalt, and manganese content in the nickel-cobalt-manganese slag, and then determine the nickel source and the cobalt source in combination with the detection result and the type of the ternary positive electrode material. and the amount of manganese source added, if the nickel, cobalt, and manganese content in the nickel-cobalt-manganese slag meets the required molar ratio, the additional nickel source, cobalt source and manganese source may not be added.

After the mixed slurry is obtained, the present invention performs a hydrothermal reaction on the mixed slurry to obtain a ternary precursor. In the present invention, the hydrothermal reaction includes a heating stage and a holding stage that are performed in sequence, the heating stage includes a first stage and a second stage that are performed in sequence, and the first stage is heated from room temperature to 200° C. The temperature is 1.5～3℃/min, preferably 2～2.5℃/min, and the temperature of the second stage is heated from 200℃ to the temperature of the holding stage, and the heating rate is 0.4～1.3℃/min, preferably 0.5～1℃/min ; The temperature of the said holding stage is 250～380 ℃, preferably 280～350 ℃, the time is preferably 2～6h, more preferably 3～4h, the pressure is preferably 5～15MPa, more preferably 8～12MPa; The hydrothermal reaction is preferably carried out in an autoclave; the present invention carries out the hydrothermal reaction under higher pressure, and the temperature rise process in the low temperature zone (room temperature to 200° C.) has little effect on the reaction, so a higher temperature rise rate can be used to heat up the reaction. , after reaching the high temperature region (above 200°C), the gas pressure changes violently with the increase of temperature, and the influence on the reaction is intensified, so it is necessary to control a lower heating rate; controlling the heating rate within the scope of the present invention can ensure that the water Stable thermal reaction.

In the present invention, the temperature in the heat preservation stage of the hydrothermal reaction is controlled at 250-380 DEG C, which can improve the reduction reaction rate and is beneficial to the control of the morphology of the precursor.

During the hydrothermal reaction, the oxides of nickel, cobalt, and manganese undergo a reduction reaction under the action of a reducing agent to generate the corresponding +2-valent metal hydroxide or carbonate, and the broken high-valent nickel, cobalt, and manganese oxides are directly reduced. and recovered to the morphology of the ternary precursor. Taking the reducing agent as sodium sulfide or ammonium sulfide as an example to illustrate the reaction that occurs in the hydrothermal reaction process, the reaction formula can be approximately expressed as follows:

When the reducing agent is sodium sulfide:

4MnO ₂ +Na ₂ S+4H ₂ O=4Mn(OH) ₂ +Na ₂ SO ₄

4Co ₃ O ₄ +Na ₂ S+12H ₂ O=12Co(OH) ₂ +Na ₂ SO ₄

When the reducing agent is ammonium sulfide:

4MnO ₂ +(NH ₄ ) ₂ S+4H ₂ O=4Mn(OH) ₂ +(NH ₄ ) ₂ SO ₄

4Co ₃ O ₄ +(NH ₄ ) ₂ S+12H ₂ O=12Co(OH) ₂ +(NH ₄ ) ₂ SO ₄

In the present invention, when carbonate exists, the above-mentioned reduction product can be converted into carbonate under the action of carbonate, for example, when ammonium salt is ammonium carbonate, the reaction formula is as follows:

Mn(OH) ₂ +(NH ₄ ) ₂ CO ₃ =MnCO ₃ +2NH ₃ ·H ₂ O

Co(OH) ₂ +(NH ₄ ) ₂ CO ₃ =CoCO ₃ +2NH ₃ ·H ₂ O

Nickel has a +2 valence and does not require further reduction. During the hydrothermal reduction of manganese-cobalt oxides, a ternary precursor is gradually formed together with the reduction product.

After the hydrothermal reaction is completed, in the present invention, the product feed liquid is preferably cooled and filtered, and then the filter cake is washed and dried in turn to obtain a ternary precursor; the washing times are preferably 2 to 5 times, and the washing uses The preservative is preferably deionized water; the present invention has no special requirements for the drying temperature, as long as the moisture in the filter cake can be completely removed by drying. In the present invention, the ternary precursor is specifically nickel cobalt manganese hydroxide or nickel cobalt manganese carbonate, and the chemical formula is Ni _x Co _y Mn _(1-xy) (OH) ₂ or Ni _x Co _y Mn _{( 1-xy)} CO ₃ , the obtained precursor of the nickel-cobalt-lithium-manganate ternary cathode material has a spherical morphology and a particle size of 4-10 nm.

The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention.

Fig. 1 is the schematic flow sheet of regeneration ternary precursor in the embodiment of the present invention, wherein nickel-cobalt-manganese slag is the solid material remaining after ternary waste selectively extracts lithium, nickel-cobalt-manganese slag and reducing agent are mixed and carry out component replenishment, Then, hydrothermal regeneration is performed to obtain a ternary precursor material, and the ternary precursor material is subjected to high-temperature solid-phase reconstruction to obtain a ternary positive electrode material.

The nickel-cobalt-manganese slag in the embodiment is obtained by the following steps:

Collect waste nickel cobalt lithium manganate ternary cathode waste (NCM523 type or NCM622 type), grind and pulverize it into powder, mix with oxalic acid in a mass ratio of 1:0.6, stir evenly, and place the mixture in a muffle furnace calcination at a temperature of 180 ° C for a period of 60 min, the muffle furnace is closed, and when the calcined product is lowered to room temperature, it is mixed with potassium oxalate in a mass ratio of 1:0.2. Place the two-stage roasting in a muffle furnace, the roasting temperature is 600 ° C, and the roasting time is 100 min; after the second-stage roasting is completed, the second-stage roasting product is mixed with water in a mass ratio of 1:5, at room temperature. After leaching for 40 minutes, the solid-liquid separation was performed to obtain a lithium-rich solution, and the remaining solid phase materials were dried to obtain nickel-cobalt-manganese slag.

Fig. 2 is the XRD pattern of the obtained nickel-cobalt-manganese slag, and it can be seen from Fig. 2 that the existence state of nickel-cobalt-manganese in the nickel-cobalt-manganese slag is mainly oxide.

Fig. 3 is a SEM image of the obtained nickel-cobalt-manganese slag. It can be seen from Fig. 3 that the morphology of the nickel-cobalt-manganese slag is irregular granular.

Example 1

Weigh 20 g of nickel-cobalt-manganese slag remaining after selective lithium extraction from ternary waste (NCM523 type), and supplement nickel sulfate, cobalt sulfate and manganese sulfate so that the molar ratio of nickel, cobalt and manganese is 5:2:3. Measure 800 mL of deionized water, accurately weigh 2.5 g of sodium sulfide, stir the raw materials evenly, pour into the autoclave, use ammonia water to adjust the pH value of the mixed slurry to 8.5, add 8.0 g of ammonium carbonate, and tighten according to the specifications The autoclave, set the reaction temperature to 280°C, control the heating rate to be 1.5°C/min before 200°C, control the temperature rise rate to 0.4°C/min after 200°C, and heat up to 280°C for a constant temperature reaction for 5 hours, and the pressure in the autoclave After the reaction was completed, the heating was stopped, the filter cake was filtered and washed twice, and dried to obtain the ternary precursor.

The ternary precursor is calcined with lithium to obtain a ternary positive electrode material of nickel cobalt lithium manganate, wherein the addition amount of lithium is 1.08 times the chemical dose ratio, and the calcination temperature is 850°C. The electrochemical performance test of the obtained ternary cathode material shows that the specific capacity of the first discharge at 0.1C can reach 152.3mAh/g, and the discharge capacity can reach 95.7% of the initial capacity after 100 discharge cycles at 0.1C, showing good charge-discharge capacity. cycle performance.

FIG. 4 is the XRD pattern of the nickel-cobalt lithium manganate ternary cathode material obtained by calcining with lithium. It can be seen from Figure 4 that the XRD peaks of the obtained nickel-cobalt lithium manganate ternary cathode material are consistent with the standard card.

FIG. 5 is a SEM image of a nickel-cobalt lithium manganate ternary cathode material obtained by calcining with lithium. It can be seen from FIG. 5 that the morphology of the obtained nickel-cobalt lithium manganate ternary cathode material is spherical.

Example 2

Weigh 20 g of nickel-cobalt-manganese slag remaining after selective lithium extraction from ternary waste (NCM523 type), and supplement nickel sulfate, cobalt sulfate and manganese sulfate so that the molar ratio of nickel, cobalt and manganese is 5:2:3. Measure 1000mL of deionized water, accurately weigh 4.5g of ammonium sulfide, stir the raw materials evenly, pour into the autoclave, add sodium hydroxide to adjust the pH of the mixed slurry to 9.0, add 10.8g of ammonium bicarbonate, press Standardly tighten the autoclave, set the reaction temperature to 300°C, control the heating rate to be 3°C/min before 200°C, and control the heating rate to 1°C/min after 200°C, and then heat up to 300°C for a constant temperature reaction for 4 hours. The internal pressure was 7.8 MPa, the heating was stopped after the reaction was completed, the filter cake was filtered and washed 4 times, and dried to obtain the ternary precursor.

The ternary precursor is calcined with lithium (conditions are the same as those in Example 1) to obtain a nickel-cobalt lithium manganate ternary positive electrode material. The electrochemical performance test of the obtained ternary cathode material shows that the specific capacity of the first discharge at 0.1C can reach 153.1mAh/g, the discharge cycle at 0.1C is 100 times, and the discharge capacity reaches 96.1% of the initial capacity, with good charge-discharge capacity. cycle performance.

Example 3

Weigh 20 g of nickel-cobalt-manganese slag remaining after selective lithium extraction from ternary waste (NCM622 type), and supplement nickel sulfate, cobalt sulfate and manganese sulfate so that the molar ratio of nickel, cobalt and manganese is 6:2:2. Measure 700 mL of deionized water, accurately weigh 1.5 g of ammonium sulfide and 1.5 g of ammonium sulfite, stir the raw materials evenly, pour them into the autoclave, add sodium hydroxide to adjust the pH of the mixed slurry to 9.5, add Ammonium oxalate 10.5g, tighten the autoclave according to the specification, set the reaction temperature to 350°C, control the heating rate to 2°C/min before 200°C, control the heating rate to 1°C/min after 200°C, and keep the temperature at 350°C. The reaction was carried out for 3h, and the pressure in the autoclave was 12MPa. After the reaction was completed, the heating was stopped, the filter cake was filtered and washed three times, and dried to obtain the ternary precursor.

The ternary precursor is calcined with lithium (conditions are the same as those in Example 1) to obtain a nickel-cobalt lithium manganate ternary positive electrode material. The electrochemical performance test of the obtained ternary cathode material shows that the specific capacity of the first discharge at 0.1C can reach 155.3mAh/g, and at 0.1C for 100 discharge cycles, the discharge capacity reaches 95.6% of the initial capacity, and it has a good charge-discharge capacity. cycle performance.

Example 4

Weigh 20 g of nickel-cobalt-manganese slag remaining after selective lithium extraction from ternary waste (NCM622 type), and supplement nickel sulfate, cobalt sulfate and manganese sulfate so that the molar ratio of nickel, cobalt and manganese is 6:2:2. Measure 1050 mL of deionized water, accurately weigh 2.0 g of sodium sulfide and 1.2 g of ammonium sulfite, stir the raw materials evenly, pour them into the autoclave, add sodium hydroxide to adjust the pH of the mixed slurry to 9.5, add Ammonium oxalate 12.8g, tighten the autoclave according to the specification, set the reaction temperature to 360°C, control the heating rate to 2.5°C/min before 200°C, control the heating rate to 1°C/min after 200°C, and keep the temperature at 360°C. The reaction was carried out for 2.5h, and the pressure in the autoclave was 16MPa. After the reaction was completed, the heating was stopped, the filter cake was filtered and washed three times, and dried to obtain the ternary precursor.

The ternary precursor is calcined with lithium (conditions are the same as those in Example 1) to obtain a nickel-cobalt lithium manganate ternary positive electrode material. The electrochemical performance test of the obtained ternary cathode material shows that the specific capacity of the first discharge at 0.1C can reach 155.6mAh/g, and the discharge capacity can reach 96.3% of the initial capacity after 100 discharge cycles at 0.1C. cycle performance.

Comparative Example 1

Weigh 20 g of nickel-cobalt-manganese slag remaining after selective lithium extraction from ternary waste (NCM523 type), and supplement nickel sulfate, cobalt sulfate and manganese sulfate so that the molar ratio of nickel, cobalt and manganese is 5:2:3. Measure 800mL of deionized water, stir evenly, pour it into the autoclave, add ammonia water to adjust the pH of the mixed slurry to 8.5, add 8.0g of ammonium carbonate, tighten the autoclave according to the specifications, and set the reaction temperature to 280°C , before 200 ℃, the heating rate is controlled to 2 ℃/min, after 200 ℃, the heating rate is controlled to 1 ℃/min, the temperature is raised to 280 ℃, and the constant temperature reaction is performed for 5 hours. The pressure in the autoclave is 6.2 MPa. The cake was made twice, and the product was obtained after drying.

The hydrothermal reaction product was calcined with lithium according to the method in Example 1, and the electrochemical performance of the obtained ternary cathode material was tested. The results showed that the specific capacity of the first discharge at 0.1C was only 65.7mAh/g, and the charge-discharge cycle Poor performance, fast decay, failed to restore electrochemical performance.

Comparative Example 2

Weigh 20 g of nickel-cobalt-manganese slag remaining after selective extraction of lithium from ternary waste (type 523), and supplement nickel sulfate, cobalt sulfate and manganese sulfate so that the molar ratio of nickel and cobalt-manganese is 5:2:3. Measure 1000mL of deionized water, accurately weigh 3.5g of ammonium sulfide, add it to the nickel-cobalt-manganese slag, stir evenly, pour it into a 2L beaker, add sodium hydroxide to adjust the pH of the mixed slurry to 9.0, add ammonium bicarbonate 10.8g, continue to stir in the water hot pot, set the temperature of the water bath to 60°C, and react at a constant temperature for 4h in the water bath to 60°C, stop heating, filter and wash the filter cake twice, and dry the filter cake to obtain the product.

The above product was calcined with lithium according to the method in Example 1, and the electrochemical performance of the obtained ternary positive electrode material was tested. The results showed that the first discharge specific capacity at 0.1C was only 72.3mAh/g, and the charge-discharge cycle performance was poor. The decay is fast and the electrochemical performance cannot be recovered.

Comparative Example 3

Weigh 20 g of nickel-cobalt-manganese slag remaining after selective extraction of lithium from ternary waste (NCM622 type), and supplement nickel sulfate, cobalt sulfate and manganese sulfate so that the molar ratio of nickel and cobalt-manganese is 6:2:2. Measure 700 mL of deionized water, accurately weigh 1.5 g of ammonium sulfide and 2.5 g of ammonium sulfite, stir evenly, pour into the autoclave, add sodium hydroxide to adjust the pH of the mixed slurry to 9.5, add 15.5 ammonium oxalate g. Tighten the autoclave according to the specification, set the reaction temperature to 150°C, raise the temperature to 150°C, react at a constant temperature for 3 hours, the pressure in the autoclave is 0.1 MPa, stop heating, filter, stir and wash twice, and dry to obtain the product.

The hydrothermal product was calcined with lithium according to the method in Example 1, and the electrochemical performance of the obtained ternary positive electrode material was tested. The results showed that the specific capacity of the first discharge at 0.1C was only 105.7mAh/g, and the charge-discharge cycle performance was relatively high. poor, the decay is also fast, and the electrochemical performance cannot be recovered.

Figures 6-9 are the SEM images of the ternary precursors obtained in Examples 1-4 in sequence, and Figures 10-12 are the SEM images of the products obtained in Comparative Examples 1-3 in sequence. According to Figures 6 to 9, it can be seen that the morphology of the ternary precursors obtained in Examples 1 to 4 is uniform spherical particles. It can be seen from Figure 3 that the morphology and raw materials (nickel-cobalt) of the ternary precursors obtained after regeneration Compared with manganese slag), a great change has taken place, and the spherical shape is basically restored. According to Figures 10 to 12, it can be seen that the hydrothermal products obtained in Comparative Examples 1 to 3 are mostly irregular particles. Although there are changes in the morphology of the nickel-cobalt-manganese slag in Figure 3, the morphology of the products has not completely recovered to spherical shape. Morphology, and some scattered and broken particles, so the electrochemical performance is poor.

According to the results of Comparative Examples 1 to 3, it can be seen that the reducing agent and the hydrothermal reaction temperature will have a greater impact on the product morphology, and only the hydrothermal reaction temperature is controlled within the scope of the present invention, and the situation without adding a reducing agent ( Under the comparative example 1), the morphology of the obtained product did not recover, the electrochemical performance of the product was poor, and a reducing agent was added, but the hydrothermal reaction temperature did not meet the requirements of the present invention (Comparative Examples 2-3), the reduction The reaction cannot be carried out effectively, and the recovery of the morphology of the ternary precursor is affected, and the electrochemical performance of the cathode material prepared by using the hydrothermal product is poor.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims

A method for utilizing nickel-cobalt-manganese slag to regenerate a ternary precursor, comprising the following steps:

Mixing nickel-cobalt-manganese slag, water and a reducing agent, adjusting the obtained mixture to alkaline, and then mixing with ammonium salt to obtain a mixed slurry; the nickel-cobalt-manganese slag is selected from waste nickel-cobalt-manganate lithium ternary positive electrode material The residual residue after lithium extraction;

The mixed slurry is subjected to a hydrothermal reaction to obtain a ternary precursor; the hydrothermal reaction includes a heating stage and a heat preservation stage that are performed in sequence, and the temperature of the heat preservation stage is 250-380°C.
The method according to claim 1, wherein the components in the mixed slurry further comprise a nickel source, a cobalt source and a manganese source.
The method according to claim 2, wherein the nickel source is nickel sulfate, the cobalt source is cobalt sulfate, and the manganese source is manganese sulfate.
The method according to claim 1, wherein the reducing agent comprises one or more of sulfide, sulfite, thiosulfate, hydrazine, hydroxylamine and aldehyde.
The method according to claim 4, wherein the sulfide includes one or more of sodium sulfide, potassium sulfide, ammonium sulfide, zinc sulfide and hydrogen sulfide; the sulfite includes sodium sulfite, sulfurous acid One or more of ammonium, potassium sulfite, zinc sulfite and sodium bisulfite; Described thiosulfate includes one or more of sodium thiosulfate, ammonium thiosulfate and potassium thiosulfate .
The method according to claim 1, 4 or 5, wherein the mass of the reducing agent is 8-40% of the mass of the nickel-cobalt-manganese slag.
The method according to claim 1, wherein the reagent used for adjusting the mixture to alkalinity comprises one or more of ammonia water, sodium hydroxide, sodium carbonate, potassium hydroxide and urea; The pH value of the mixture was adjusted to 8.5-12.
The method according to claim 1, wherein the ammonium salt comprises one or more of ammonium carbonate, ammonium bicarbonate and ammonium oxalate.
The method according to claim 1 or 8, wherein the mass of the ammonium salt is 10-80% of the mass of the nickel-cobalt-manganese slag.
The method according to claim 1, characterized in that, the holding time is 2-6h, and the pressure is 5-15MPa.
The method according to claim 1, wherein the heating stage comprises a first stage and a second stage which are carried out in sequence, the first stage is heated from room temperature to 200°C, and the heating rate is 1.5-3°C/min , the temperature of the second stage is raised from 200°C to the temperature of the heat preservation stage, and the heating rate is 0.4-1.3°C/min.
The method according to claim 1, wherein the waste nickel cobalt lithium manganate ternary positive electrode material comprises NCM523 and/or NCM622.