CN110265742B - Method and system for recycling and preparing composite anode material from leftover materials and defective products - Google Patents

Abstract

The invention discloses a method and a system for recycling and preparing a composite cathode material from leftover materials and defective products. The method comprises the following steps: classifying and crushing waste leftover materials and defective products to obtain a positive plate; removing the binder in the obtained positive plate, then performing cold quenching, drying and screening to separate the positive plate, and then performing roasting treatment to obtain positive electrode powder; and performing ball milling and sintering treatment on the mixture containing the positive electrode powder, the lithium salt and the coating raw material to obtain the repaired composite positive electrode material. According to the invention, the positive electrode powder and the foil are preferentially stripped by dry separation, and the separation process is a physical process, so that the method is green and environment-friendly; and then, roasting the anode powder to remove carbon powder and organic matters, and then modifying and sintering to obtain the repaired composite anode powder which can be directly reused for battery production. The method has the advantages of simple process flow, high recovery rate, good consistency of the obtained product, stable performance and strong application potential.

Description

Method and system for recycling and preparing composite anode material from leftover materials and defective products

Technical Field

The invention relates to a method for recycling a lithium battery positive electrode, in particular to a method and a system for recycling and preparing a composite positive electrode material from leftover materials and defective products, and belongs to the technical field of lithium battery recycling.

Background

Lithium and lithium compounds are important energy materials and are widely applied to energy storage power supplies and national defense construction. The lithium ion battery has the characteristics of high energy density, high voltage platform, small self-discharge, no memory effect and the like, has been developed as a main energy source of 3C electronic products, and occupies more than 80% of the consumer electronics market. Benefiting the high growth of the new energy vehicle industry, realizing the delivery of 39.2GWH by domestic power batteries in 2017, and predicting that the CAGR is expected to be kept more than 30% in the next three years. The service life of a battery of a passenger vehicle is generally 4-6 years, while the service life of the battery of an electric commercial vehicle is only about 3 years due to long driving range and frequent charging. The recovery of the power battery is predicted to be close to 40Gwh in 2020, and the recovery of the power battery is predicted to be close to 70Gwh in 2022, and the market scale is expected to break through billions of yuan in terms of metal-containing value.

In the process of producing the lithium battery, the management level of each factory is different, and more or less defective products, particularly a certain amount of leftover materials of the positive plate exist. The leftover materials in the production process are not contacted with the electrolyte, are not subjected to lithium ion extraction, have no change in crystal structure, but have greatly reduced cycle performance and serious attenuation of the powder recovered by the extraction. Lithium oxide is easily formed on the surface of the positive electrode in stacking or the positive electrode powder structure is damaged in the alkalization and stripping processes. How to scientifically and efficiently repair the anode powder and directly recycle the anode powder is particularly important.

The current lithium battery recovery technology mainly focuses on two aspects of hydrometallurgy and pyrometallurgy. The methods realize the recovery of valuable metal elements or the synthesis of precursors from waste lithium batteries. The hydrometallurgy method mainly adopts alkaline solution and acid leaching and then adopts fractional precipitation or extraction method to recover valuable metal elements. The used alkali mainly comprises sodium hydroxide and potassium hydroxide; the acid is divided into inorganic acid and organic acid, such as common inorganic acid hydrochloric acid, sulfuric acid, nitric acid and even phosphoric acid, the organic acid includes citric acid, malic acid and the like, the organic extractant includes P204, P507 and the like, and most recovered products are sulfate or precursors. The pyrometallurgy mainly uses high-temperature calcination to remove organic matters and binders, and then the primary product is obtained by screening, magnetic separation and impurity removal.

For example, in chinese patent CN103199230A, a pretreatment is performed to obtain powder of a positive electrode material, then an acid dissolution is performed to remove impurities to obtain a mixed solution containing nickel and manganese, acetate is used as a complexing agent, a nickel source or a manganese source is newly added, then an electrolysis is performed in an electrolysis cell to deposit nickel and manganese on a titanium material at the same time, and a lithium source is added to the deposited nickel-manganese mixture in proportion to perform sintering, so as to obtain lithium nickel manganese oxide. The method has a good idea, but lithium salt is not purified, so that precious lithium resources are wasted. In the chinese patent CN10871048A, alkali is used to dissolve aluminum foil, then valuable metal elements of the positive electrode material are leached by acid, impurities such as aluminum, iron and the like are removed, pH is adjusted, products such as manganese sulfate, cobalt sulfate, nickel sulfate and the like are obtained by extracting manganese, cobalt and nickel by using P204 or P507, and products such as cobalt oxide, nickel oxide and the like are further prepared by high-temperature calcination. The method does not clearly recover lithium, and the organic solvent extraction method is adopted, so that the volatilization of organic matters and the treatment of organic waste liquid are difficult. In addition, in chinese patent CN106785167A, a high temperature calcination method is used to recover ternary nickel, cobalt and manganese materials, the high temperature calcination is performed for 3-7min, then the materials are crushed, sieved and the like to obtain the anode material, and then ball milling, water immersion and solid-liquid separation are performed to obtain a lithium-containing solution. The method is environment-friendly, but the recovery rate of lithium is low, and other metal elements are not well recycled.

Few reports of recycling leftover materials generated in the production process of a battery cell factory mainly focus on selective leaching of lithium recovered by a lithium iron phosphate anode or on adding lithium salt, phosphate radical and iron in proportion for re-sintering. For example, in chinese patent CN106505273A, a powder is obtained by alkali dissolution and organic solvent stripping, and then lithium iron phosphate cathode powder is recovered by baking and calcining.

The recovery technology of the waste lithium batteries is more, the early recovery technology only focuses on the purification of certain metal elements with the highest economic value, the method is single, the cobalt in the waste lithium cobaltate is typically recovered, and the lithium is not comprehensively recovered. The method for recycling the valuable metals of the waste batteries most at present is pyrogenic process-acid leaching or alkali dissolution-acid leaching, and then the valuable metal elements are recycled by combining the modes of precipitation, electrochemistry, extraction and the like. For example, in the process technologies of alkali dissolution, acid leaching and nickel-cobalt-manganese extraction, although the extraction efficiency of the solvent extraction method is high and the purity of the obtained product is high, the organic solvent is more or less dissolved and damaged and is volatile to pollute the environment, so that secondary pollution is caused, and in addition, the extraction method has high cost and limitation in industrial production. If the equipotential of nickel and cobalt is close, nickel and cobalt in the electrodeposition technology are synchronously deposited to form cobalt-nickel alloy, which affects subsequent purification and restricts the application of the enlargement. Other methods such as an ion exchange method, sulfide bacteria leaching and the like can successfully recover valuable metal elements, but the methods have certain limitations, such as complex operation and complex steps of the ion exchange method, and are only suitable for separation and purification of a small amount of ions; the culture and use conditions of the bacteria in the sulfide bacteria leaching technology are harsh, and the application and popularization of the technology are restricted by factors such as difficult industrialization. In addition, the existing waste battery recovery process basically precipitates or extracts nickel, cobalt and manganese, and then purifies the lithium-containing solution, so that a large amount of acid and alkali is consumed, the process is long, and the product is a primary raw material for synthesizing the anode material. In addition, the conventional dry-method recycled cathode powder contains a little of metal impurities or the original material structure is damaged in the recycling process, and the recycled powder cannot be directly recycled or the stability and consistency of the material are poor after simple modification, so that recycling is restricted.

Disclosure of Invention

The invention mainly aims to provide a method and a system for recycling and preparing a composite cathode material from leftover materials and defective products, thereby overcoming the defects in the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme:

the embodiment of the invention provides a method for recycling and preparing a composite cathode material from leftover materials and defective products, which comprises the following steps:

classifying and crushing waste leftover materials and defective products to obtain a positive plate;

removing the binder in the obtained positive plate, then performing cold quenching, drying and screening to separate the positive plate, and then performing roasting treatment to obtain positive electrode powder;

and performing ball milling and sintering treatment on the mixture containing the positive electrode powder, the lithium salt and the coating raw material to obtain the repaired composite positive electrode material.

In some embodiments, the method for recycling and preparing the composite cathode material from the leftover materials and the defective products specifically comprises the following steps:

(1) classifying and crushing waste leftover materials and defective products to obtain a positive plate;

(2) carrying out low-temperature heat treatment on the positive plate, at least removing the binder in the positive plate, then carrying out cold quenching, drying and screening to separate the positive plate, and then carrying out roasting treatment to obtain positive electrode powder;

(3) uniformly mixing the roasted anode powder, lithium salt and a coating raw material, carrying out ball milling on the obtained mixture, and then carrying out sintering treatment in a protective atmosphere to enable the coating raw material to be coated and modified on the surface of the anode powder so as to form a coating layer, thereby obtaining the repaired composite anode material.

The embodiment of the invention also provides a system for recycling and preparing the composite cathode material from the leftover materials and defective products, which comprises the following steps:

a sorting and crushing mechanism capable of sorting and crushing the waste leftover materials and inferior-quality products;

a low-temperature heat treatment mechanism capable of removing the binder in the positive electrode sheet;

the cold quenching-drying-screening mechanism can perform cold quenching, drying and screening on the positive plate;

the roasting mechanism can roast the screened positive plate to obtain positive electrode powder;

a ball milling mechanism capable of uniformly mixing the positive electrode powder, the lithium salt and the coating raw material to obtain a mixture;

a sintering mechanism capable of subjecting the mixture to a sintering process.

Compared with the prior art, the invention has the beneficial effects that:

1) the positive plate stripping technology is advanced, and the separation effect is good. The method is characterized in that a pyrolytic binder is combined with quenching, and the shrinkage and ductility inconsistency at different temperatures is utilized to peel the positive electrode material from the positive electrode plate, the surface of the positive electrode plate is smooth and is not oxidized, and the recovered positive electrode powder does not contain metal debris; the process is simple, and organic matters or impurity ions are not introduced;

2) the invention has novel recovery and repair concept. According to the invention, the screening of the anode powder is combined with the surface repair technology, the inorganic material is coated on the surface layer of the recovered anode powder, so that the direct contact of electrolyte to the anode material is avoided, meanwhile, a lithium source is supplemented to the anode material, the material is modified, the obtained powder can be directly reused for lithium battery production, the recovered and repaired anode material reaches or even exceeds the cycle performance of a brand new anode material, and the capacity retention rate and the cycle performance are both more excellent than those of the same type of anode material;

3) the repair technology is new. The method comprises the steps of adding lithium salt and coating raw materials into recovered positive electrode powder, ball-milling, uniformly mixing and sintering, and coating a lithium-rich layer on the surface of the recovered powder, wherein the thickness of the coating layer is 1-50 nm. The coated and modified anode material is uniform and spherical, has excellent cycle performance and can be reused for the production of lithium batteries;

4) the method takes dry recovery as a main means and combines with surface modification to recover the anode material and realize restoration and regeneration, the whole process mainly adopts physical separation, the recovery process is advanced, the whole flow has no discharge of mother liquor or acidified slag, the heat treatment process is mild and controllable, green and environment-friendly, secondary environmental pollution is avoided, the traditional hydrometallurgy process is avoided, the powder quality in the pretreatment stage is strictly controlled, the material is directly mixed and secondarily sintered, the process equipment is advanced and easy to operate, the parameters of each process section are accurate and controllable, the operation is simple and convenient, the automation degree is high, the amplification is easy, and the method is suitable for industrial production.

Drawings

Fig. 1 is a schematic flow chart of a method for recovering and preparing a composite positive electrode material from scrap and inferior products according to an exemplary embodiment of the present invention.

Fig. 2 is an SEM image of the coated cathode material obtained in an exemplary embodiment of the present invention.

Fig. 3 is an XRD spectrum of the coated cathode material obtained at different processing temperatures in an exemplary embodiment of the present invention.

Fig. 4 is a 5C rate cycle plot of the coated positive electrode material in an exemplary embodiment of the invention.

Fig. 5 is a rate cycle plot of the coated positive electrode material in an exemplary embodiment of the invention.

FIG. 6 is an EDS spectrum of the pre-fired powder in an exemplary embodiment of the invention.

Detailed Description

In view of the defects of low recovery efficiency and long process length of the existing waste leftover materials, the inventor of the present invention provides a technical scheme of the invention through long-term research and a large amount of practice, and the technical scheme mainly comprises the process steps of leftover material classification, crushing, low-temperature heat treatment, roasting treatment, ultrasonic separation, screening, surface modification (lithium salt addition ball milling, high-temperature sintering) and the like. The method does not carry out acidification leaching on the powder, is different from the traditional process of leaching the anode powder and respectively recovering elements such as nickel, cobalt, manganese, lithium and the like, overcomes the defect of redundancy of the original process and avoids secondary pollution. The recovered powder assembled battery has excellent high rate performance and can be directly reused as the positive electrode of the lithium battery. The method has the characteristics of simple process, environmental protection and direct reuse of valuable elements.

The technical solution, its implementation and principles, etc. will be further explained as follows.

As one aspect of the technical solution of the present invention, there is provided a method for recycling a composite positive electrode material from scrap and inferior products, comprising:

classifying and crushing waste leftover materials and defective products to obtain a positive plate;

removing the binder in the obtained positive plate, then performing cold quenching, drying and screening to separate the positive plate, and then performing roasting treatment to obtain positive electrode powder;

and performing ball milling and sintering treatment on the mixture containing the positive electrode powder, the lithium salt and the coating raw material to obtain the repaired composite positive electrode material.

In some embodiments, the method for recycling and preparing the composite cathode material from the leftover materials and the defective products specifically comprises the following steps:

(1) classifying and crushing waste leftover materials and defective products to obtain a positive plate;

(2) carrying out low-temperature heat treatment on the positive plate, at least removing the binder in the positive plate, then carrying out cold quenching, drying and screening to separate the positive plate, and then carrying out roasting treatment to obtain positive electrode powder;

(3) uniformly mixing the roasted anode powder, lithium salt and a coating raw material, carrying out ball milling on the obtained mixture, and then carrying out sintering treatment in a protective atmosphere to enable the coating raw material to be coated and modified on the surface of the anode powder so as to form a coating layer, thereby obtaining the repaired composite anode material.

In some embodiments, the waste scrap is derived from waste pole pieces generated in a lithium battery production process, for example, waste ternary lithium battery scrap, where the lithium battery includes a nickel-cobalt-manganese ternary lithium battery, and the main type of the lithium battery uses a typical ternary nickel-cobalt-manganese powder as a positive electrode, and there are mainly four typical types, such as 111, 442, 523, 622, 811, 9055, and the like, but not limited thereto.

Furthermore, the waste leftover material type applicable to the invention can be suitable for repairing the anode materials of lithium iron phosphate, lithium manganate, nickel cobalt aluminum ternary batteries and other types of batteries besides the nickel cobalt manganese ternary material, and the sintering atmosphere can be controlled and different types of lithium-rich materials can be coated according to actual conditions.

In some embodiments, in the step (2), the temperature of the low-temperature heat treatment is 350 to 650 ℃ for 1 to 360 min.

In some embodiments, step (2) specifically comprises: and (3) instantly reducing the temperature of the positive plate from 350-650 ℃ to 0-30 ℃ by adopting a quenching medium, drying at 30-100 ℃, sieving, and finally roasting at 500-850 ℃ for 0.1-10 h.

Further, the quenching medium includes ice water, cold air, or the like.

Furthermore, the aperture of the screening is 1.25-2000 mu m.

Further, the step (2) comprises: the low-temperature heat treatment and the quenching are alternately carried out, namely, the quenching process and the pyrolysis treatment process can be repeatedly converted.

In some embodiments, in step (3), the process conditions of the sintering treatment include: the sintering temperature is two stages, the sintering temperature in the first stage is 450-650 ℃, the sintering temperature in the second stage is 750-950 ℃, the sintering time is 0.5-24 h, the temperature rise rate is 1-20 ℃ min, and the sintering atmosphere comprises compressed air, a high-purity oxygen atmosphere or an inert gas atmosphere and the like.

In some embodiments, the lithium salt includes any one or a combination of two or more of lithium hydroxide, lithium carbonate, lithium oxalate, lithium fluoride, and the like, but is not limited thereto.

In some embodiments, the coating material includes any one or a combination of two or more of alumina, silica, titania, yttria, and the like, but is not limited thereto.

Further, the molar ratio of the lithium salt to the cathode powder subjected to roasting treatment is 1.01-1.10: 1.

further, the molar ratio of the coating raw material to the cathode powder subjected to roasting treatment is 1-10: 100, i.e., the amount of the coating material is 1 to 10% by mole of the positive electrode powder.

Further, the thickness of the coating layer is 1-50 nm.

Further, the material of the coating layer comprises LiYO₂、Li₄SiO₄、Li₄TiO₄And the like, or a combination of two or more thereof, but is not limited thereto.

As a more specific embodiment of the present invention, referring to fig. 1, the method for recycling and preparing the composite cathode material from scrap and defective products may specifically include the following steps:

the method comprises the steps of taking waste pole pieces produced in the production process of the lithium battery as raw materials, classifying and crushing to obtain positive pole pieces, removing binders through low-temperature heat treatment, quenching, drying and screening to obtain positive pole powder and foil containing carbon powder. The foil is directly recycled and sold to downstream enterprises. And (3) roasting the carbon powder-containing positive electrode to remove organic matters and carbon powder, adding a lithium salt and a coating raw material in a certain molar ratio, mixing, ball-milling, and sintering the positive electrode material to obtain the repaired composite positive electrode material.

Furthermore, the invention adopts dry recovery to directly obtain the primary powder. The binder is pyrolyzed by adopting a controllable heat treatment process, and primary materials are obtained by grading and screening, and the foil is separated, so that no new impurities are introduced.

The composite anode material is synthesized by sintering the secondary mixed material. The powder obtained by screening and the surface modification material are mixed and then subjected to solid phase sintering, so that the best use is made, a trace amount of metal oxide is coated on the surface of the anode material, the direct contact of electrolyte is avoided, and the circulation stability of the anode material is improved.

As one aspect of the technical solution of the present invention, there is provided a system for recycling and preparing a composite positive electrode material from scrap and inferior products, comprising:

a sorting and crushing mechanism capable of sorting and crushing the waste leftover materials and inferior-quality products;

a low-temperature heat treatment mechanism capable of removing the binder in the positive electrode sheet;

the cold quenching-drying-screening mechanism can perform cold quenching, drying and screening on the positive plate;

the roasting mechanism can roast the screened positive plate to obtain positive electrode powder;

a ball milling mechanism capable of uniformly mixing the positive electrode powder, the lithium salt and the coating raw material to obtain a mixture;

a sintering mechanism capable of subjecting the mixture to a sintering process.

Further, the system may specifically and mainly include, but is not limited to, a cutter, a standard screen, a pyrolysis kiln, a muffle furnace, a tube furnace, a ball mill, a winnowing device, a drying oven, an eddy current classifier, a reaction vessel, and the like.

In conclusion, the method separates the anode powder and the foil preferentially by a dry method, and the separation process is a physical process and is green and environment-friendly; and then, roasting the anode powder to remove carbon powder and organic matters, and then modifying and sintering to obtain the repaired composite anode powder which can be directly reused for battery production. The method has the advantages of simple process flow, high recovery rate, good consistency of the obtained product, stable performance and strong application potential.

The technical solutions of the present invention will be described in further detail below with reference to several preferred embodiments and accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. The test methods in the following examples, which are not specified under specific conditions, are generally carried out under conventional conditions.

Example 1

Waste ternary lithium battery leftover materials of a certain type are used as raw materials. Firstly, cutting waste leftover materials into 2kg of chips of 0.5x0.5cm, putting the chips into a pyrolysis kiln for heat treatment at the temperature of 650 ℃ for 10min, taking out the chips when the chips are hot, directly adding the chips into ice water for quenching, instantly reducing the temperature from 650 ℃ to 30 ℃, simultaneously carrying out ultrasonic oscillation treatment for 20min to strip a positive electrode material and an aluminum foil, and sieving and filtering the aluminum foil and black powder by using a large hole to obtain the aluminum foil with a smooth surface. Filtering the black powder, drying at 50 ℃, screening for the second time, and filtering out metal debris; obtaining the carbon-containing anode powder. And roasting the carbon-containing powder in an air atmosphere at the temperature of 850 ℃ for 0.5 h. Sampling and weighing, respectively adding 5% and 8% of lithium salt and titanium dioxide in excess, ball-milling and uniformly mixing, wherein the molar ratio of the lithium salt to the anode powder subjected to roasting treatment is 1.01: 1, the molar ratio of titanium dioxide to the cathode powder subjected to roasting treatment is 1: 100. sintering the uniformly mixed materials in a tube furnace, heating at the rate of 5 ℃/min to 470 ℃, keeping the temperature for 4 hours, then continuously heating to 850 ℃, keeping the temperature for 8 hours, and then naturally cooling. The sintering atmosphere is high-purity oxygen atmosphere sintering. The coated and modified material is assembled into a battery, the electrochemical performance is tested, the 5C cycle initial capacity of the anode powder body after titanium coating modification reaches 115mAh/g, and the capacity retention rate reaches over 90 percent after 125 circles.

The process flow is short, the process is green and environment-friendly, the recovery rates of the metal foil and the anode powder are high, and the anode material with excellent performance is obtained by combining the surface modification technology. The method is simple and convenient to operate and easy for large-scale production, and the recovered and repaired anode material can be directly reused for the production of the lithium battery.

Example 2

Waste ternary lithium battery leftover materials of a certain type are used as raw materials. Firstly, cutting waste leftover materials into 1.2kg of chips of 0.2x0.2cm, putting the chips into a pyrolysis furnace, carrying out heat treatment at the temperature of 400 ℃ for 6h, taking out the chips when the chips are hot, directly adding the chips into ice water for quenching, instantly reducing the temperature from 550 ℃ to 20 ℃, simultaneously carrying out ultrasonic oscillation treatment for 15min, stripping a positive electrode material from an aluminum foil, and filtering the aluminum foil and black powder by using macroporous screening to obtain the aluminum foil with a smooth surface. Filtering the black powder, drying at 80 ℃, and then sieving for the second time to filter metal debris; obtaining the carbon-containing anode powder. And (3) roasting the carbon-containing powder in an air atmosphere at the temperature of 700 ℃ for 10 hours. Sampling and weighing, adding lithium salt and silicon dioxide with the excessive amount of 8%, ball-milling and uniformly mixing, wherein the molar ratio of the lithium salt to the anode powder subjected to roasting treatment is 1.03: 1, the molar ratio of silicon dioxide to the anode powder subjected to roasting treatment is 3: 100. sintering the uniformly mixed materials in a tube furnace, heating at the rate of 5 ℃/min, keeping the temperature at 450 ℃ for 4h, then continuously heating to 950 ℃, keeping the temperature for 8h, and then naturally cooling. Compressed air is introduced for sintering in the sintering process. The coated and modified material is assembled into a battery, the electrochemical performance is tested, the 5C cycle initial capacity of the anode powder body after titanium coating modification reaches 109mAh/g, and the capacity retention rate reaches 95% after 100 circles.

The process flow is short, the process is green and environment-friendly, the recovery rates of the metal foil and the anode powder are high, and the anode material with excellent performance is obtained by combining the surface modification technology. The method is simple and convenient to operate and easy for large-scale production, and the recovered and repaired anode material can be directly reused for the production of the lithium battery.

Example 3

Waste ternary lithium battery leftover materials of a certain type are used as raw materials. Firstly, cutting waste leftover materials into 2.5kg of scraps of 0.5x0.5cm, putting the scraps into a pyrolysis furnace, carrying out heat treatment at the temperature of 650 ℃ for 1min, taking out the scraps when the scraps are hot, directly adding the scraps into ice water for quenching, instantly reducing the temperature from 450 ℃ to 10 ℃, simultaneously carrying out ultrasonic vibration treatment for 20min, stripping a positive electrode material and an aluminum foil, and filtering the aluminum foil and black powder by using macroporous screening to obtain the aluminum foil with a smooth surface. Filtering the black powder, drying at 60 ℃, screening for the second time, and filtering out metal debris; obtaining the carbon-containing anode powder. And (3) roasting the carbon-containing powder in an oxygen-enriched atmosphere at the temperature of 750 ℃ for 2 hours. Sampling and weighing, adding lithium salt and yttrium oxide with the excessive amount of 3%, ball-milling and uniformly mixing, wherein the molar ratio of the lithium salt to the cathode powder subjected to roasting treatment is 1.05: 1, the molar ratio of yttrium oxide to the cathode powder subjected to roasting treatment is 5: 100. sintering the uniformly mixed materials in a tube furnace, heating at the rate of 1 ℃/min to 650 ℃, keeping the temperature for 6 hours, then continuously heating to 750 ℃, keeping the temperature for 24 hours, and then naturally cooling. The sintering atmosphere is oxygen-enriched sintering. The coated and modified material is assembled into a battery, the electrochemical performance is tested, the 5C cycle initial capacity of the anode powder body after titanium coating modification reaches 125mAh/g, and the capacity retention rate reaches 94% after 100 circles.

The process flow is short, the process is green and environment-friendly, the recovery rates of the metal foil and the anode powder are high, and the anode material with excellent performance is obtained by combining the surface modification technology. The method is simple and convenient to operate and easy for large-scale production, and the recovered and repaired anode material can be directly reused for the production of the lithium battery.

Example 4

Waste ternary lithium battery leftover materials of a certain type are used as raw materials. Firstly, cutting waste leftover materials into 2.2kg of chips of 0.5x0.5cm, putting the chips into a pyrolysis furnace for heat treatment at 500 ℃ for 1h, taking out the chips when the chips are hot, directly adding the chips into ice water for quenching, instantly reducing the temperature from 350 ℃ to 0 ℃, simultaneously carrying out ultrasonic vibration treatment for 20min to strip the anode material and the aluminum foil, and filtering the aluminum foil and black powder by using macroporous screening to obtain the aluminum foil with a smooth surface. Filtering the black powder, drying at 50 ℃, screening for the second time, and filtering out metal debris; obtaining the carbon-containing anode powder. The carbon-containing powder is roasted in an oxygen-enriched atmosphere at the temperature of 500 ℃ for 1 h. Sampling and weighing, adding 5% of lithium salt and tin oxide in excess, ball-milling and uniformly mixing, wherein the molar ratio of the lithium salt to the cathode powder subjected to roasting treatment is 1.08: 1, the molar ratio of the tin oxide to the cathode powder subjected to roasting treatment is 8: 100. sintering the uniformly mixed materials in a tube furnace, heating at a rate of 10 ℃/min to 480 ℃, keeping the temperature for 6 hours, then continuously heating to 820 ℃, keeping the temperature for 10 hours, and then naturally cooling. The sintering atmosphere is oxygen-enriched sintering. The coated and modified material is assembled into a battery, the electrochemical performance is tested, the 5C cycle initial capacity of the cathode powder body after titanium coating modification reaches 128mAh/g, and the capacity retention rate reaches 93% after 100 circles.

The process flow is short, the process is green and environment-friendly, the recovery rates of the metal foil and the anode powder are high, and the anode material with excellent performance is obtained by combining the surface modification technology. The method is simple and convenient to operate and easy for large-scale production, and the recovered and repaired anode material can be directly reused for the production of the lithium battery.

Example 5

Waste ternary lithium battery leftover materials of a certain type are used as raw materials. Firstly, cutting waste leftover materials into 1.5kg of chips of 0.8x0.8cm, putting the chips into a pyrolysis furnace, carrying out heat treatment at 350 ℃ for 6h, taking out the chips when the chips are hot, directly adding the chips into ice water for quenching, instantly reducing the temperature from 500 ℃ to 30 ℃, simultaneously carrying out ultrasonic oscillation treatment for 30min to strip a positive electrode material and an aluminum foil, and filtering the aluminum foil and black powder by using macroporous screening to obtain the aluminum foil with a smooth surface. Filtering the black powder, drying at 100 ℃, and then carrying out secondary screening to filter metal debris; obtaining the carbon-containing anode powder. And roasting the carbon-containing powder in a pure oxygen atmosphere at the temperature of 850 ℃ for 0.1 h. Sampling and weighing, adding lithium salt and yttrium oxide with the excessive amount of 3%, ball-milling and uniformly mixing, wherein the molar ratio of the lithium salt to the cathode powder subjected to roasting treatment is 1.10: 1, the molar ratio of yttrium oxide to the cathode powder subjected to roasting treatment is 10: 100. sintering the uniformly mixed materials in a tube furnace, wherein the heating rate is 20 ℃/min, keeping the temperature at 650 ℃ for 0.5h, then continuously heating to 900 ℃, keeping the temperature for 10h, and then naturally cooling. The sintering atmosphere is oxygen-enriched sintering. The coated and modified material is assembled into a battery, the electrochemical performance is tested, the 5C cycle initial capacity of the anode powder body after titanium coating modification reaches 118mAh/g, and the capacity retention rate reaches 92% after 100 circles.

The process flow is short, the process is green and environment-friendly, the recovery rates of the metal foil and the anode powder are high, and the anode material with excellent performance is obtained by combining the surface modification technology. The method is simple and convenient to operate and easy for large-scale production, and the recovered and repaired anode material can be directly reused for the production of the lithium battery.

Fig. 2 is an SEM image of the coated positive electrode material obtained in an exemplary embodiment of the present invention, fig. 3 is an XRD spectrum of the coated positive electrode material obtained at different processing temperatures, fig. 4 is a 5C-magnification cycle diagram of the coated positive electrode material, and fig. 5 is a magnification cycle diagram of the coated positive electrode material obtained in an exemplary embodiment of the present invention. An EDS spectrum of the pre-fired powder in an exemplary embodiment of the invention is shown in FIG. 6.

In conclusion, according to the technical scheme of the invention, the positive electrode powder and the foil are preferentially stripped by a dry separation method, and the separation process is a physical process and is green and environment-friendly; and then, roasting the anode powder to remove carbon powder and organic matters, and then modifying and sintering to obtain the repaired composite anode powder which can be directly reused for battery production. The method has the advantages of simple process flow, high recovery rate, good consistency of the obtained product, stable performance and strong application potential.

The aspects, embodiments, features and examples of the present invention should be considered as illustrative in all respects and not intended to be limiting of the invention, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

The use of headings and chapters in this disclosure is not meant to limit the disclosure; each section may apply to any aspect, embodiment, or feature of the disclosure.

Throughout this specification, where a composition is described as having, containing, or comprising specific components or where a process is described as having, containing, or comprising specific process steps, it is contemplated that the composition of the present teachings also consist essentially of, or consist of, the recited components, and the process of the present teachings also consist essentially of, or consist of, the recited process steps.

Unless specifically stated otherwise, use of the terms "comprising", "including", "having" or "having" is generally to be understood as open-ended and not limiting.

It should be understood that the order of steps or the order in which particular actions are performed is not critical, so long as the teachings of the invention remain operable. Further, two or more steps or actions may be performed simultaneously.

In addition, the inventors of the present invention have also made experiments with other materials, process operations, and process conditions described in the present specification with reference to the above examples, and have obtained preferable results.

While the invention has been described with reference to illustrative embodiments, it will be understood by those skilled in the art that various other changes, omissions and/or additions may be made and substantial equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated any use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another.

Claims (4)

1. A method for recycling and preparing a composite cathode material from leftover materials and defective products is characterized by comprising the following steps:

(1) cutting waste ternary lithium battery leftover materials into chips;

(2) carrying out heat treatment on the scraps, wherein the temperature of the heat treatment is 350-650 ℃, the time is 1-360 min, taking out the scraps while the scraps are hot, directly adding the scraps into ice water for quenching, instantly reducing the temperature from 350-650 ℃ to 0-30 ℃, alternately carrying out the heat treatment and the quenching, simultaneously carrying out ultrasonic vibration treatment for 15-30 min, stripping the anode material from the aluminum foil, and filtering the aluminum foil and black powder by using macroporous screening to obtain the aluminum foil with a smooth surface; filtering water of black powder, drying at 50-100 ℃, and then carrying out secondary screening, wherein the aperture of the screening is 1.25-2000 mu m, and filtering metal fragments to obtain carbon-containing anode powder; roasting the carbon-containing anode powder at 500-850 ℃ for 0.1-10 h in an air atmosphere, an oxygen-enriched atmosphere or a pure oxygen atmosphere to obtain anode powder;

(3) uniformly mixing any one of silicon dioxide, titanium dioxide and yttrium oxide with the anode powder and lithium salt which are subjected to roasting treatment, ball-milling the obtained mixture, and then carrying out oxygen-enriched atmosphereSintering treatment is carried out, wherein the sintering temperature is two stages, the sintering temperature in the first stage is 450-650 ℃, the sintering temperature in the second stage is 750-950 ℃, the sintering time is 0.5-24 h, the heating rate is 1-20 ℃/min, silicon dioxide, titanium dioxide or yttrium oxide is coated and modified on the surface of the anode powder body to form a coating layer, and a repaired composite anode material is obtained, the lithium salt is selected from any one or the combination of more than two of lithium hydroxide, lithium carbonate, lithium oxalate and lithium fluoride, the thickness of the coating layer is 1-50nm, and the material of the coating layer is Li₄SiO₄、Li₄TiO₄Or LiYO₂The molar ratio of the lithium salt to the cathode powder subjected to roasting treatment is 1.01-1.10: 1, the molar ratio of the silicon dioxide, the titanium dioxide or the yttrium oxide to the anode powder subjected to roasting treatment is 1-10: 100.

2. the method for recovering and preparing a composite positive electrode material from scraps and inferior-quality products according to claim 1, wherein: the waste ternary lithium battery leftover materials are derived from waste pole pieces produced in the production process of lithium batteries, and the lithium batteries are selected from nickel-cobalt-manganese ternary lithium batteries or nickel-cobalt-aluminum ternary lithium batteries.

3. The method for recovering and preparing a composite positive electrode material from scraps and inferior-quality products according to claim 2, wherein: the type of the nickel-cobalt-manganese ternary lithium battery is selected from 111, 442, 523, 622, 811 or 9055 types.

4. A system for recovering and preparing a composite positive electrode material from scrap and defective products, which is used in the method according to any one of claims 1 to 3, comprising:

the classifying and crushing mechanism can classify and crush waste ternary lithium battery leftover materials;

a low-temperature heat treatment mechanism capable of removing the binder in the positive electrode sheet;

the cold quenching-drying-screening mechanism can perform cold quenching, drying and screening on the positive plate;

the roasting mechanism can roast the screened positive plate to obtain positive electrode powder;

a ball milling mechanism capable of uniformly mixing the positive electrode powder, the lithium salt and the coating raw material to obtain a mixture;

a sintering mechanism capable of subjecting the mixture to a sintering process.

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