CN117096486A - Repairing and regenerating method for waste lithium ion battery anode material - Google Patents

Abstract

The invention provides a repairing and regenerating method of a waste lithium ion battery anode material, and belongs to the technical field of battery material recovery. Firstly, performing ball milling treatment on an aged positive electrode material of a waste lithium ion battery to obtain a single-particle positive electrode material; mixing the single-particle positive electrode material with the lithium-rich salt mixture, and then performing primary sintering to obtain a lithium-supplementing single-particle positive electrode material; and finally, mixing the lithium-supplementing single-particle positive electrode material with a lithium compound, and then performing secondary sintering to obtain the repaired single-crystal positive electrode material. According to the invention, the multicomponent lithium-rich salt mixture and the aged positive electrode material are mixed, the lithium supplementing amount required for repairing the positive electrode material is not required to be accurately controlled, the purpose of melting and supplementing lithium can be realized at a lower temperature, and the operation is not required to be at high temperature and high pressure, so that the method is safer and has low energy consumption.

Description

A method for repairing and regenerating waste lithium-ion battery cathode materials

Technical field

The present invention relates to the technical field of battery material recycling, and in particular to a method for repairing and regenerating waste lithium-ion battery cathode materials.

Background technique

Lithium-ion batteries have attracted much attention due to their significant advantages in energy density, rate performance and cycle life. In recent years, with the rapid development of renewable energy and uneven spatial and temporal distribution of power generation, the demand for energy storage has become increasingly urgent. As an efficient energy storage carrier, lithium-ion batteries are widely used in home and commercial energy storage systems, effectively improving grid stability and energy supply security. The rapid rise of the electric vehicle industry has also driven the growing demand for high-energy-density lithium-ion batteries, especially ternary nickel cobalt lithium manganate (NCM) cathode materials. However, after lithium-ion batteries undergo long cycles during use, their capacity and voltage will inevitably decrease due to factors such as reversible lithium loss, material structure transformation, and ohmic resistance increase, making them no longer suitable for continued use. This will cause A large number of used batteries are in urgent need of proper disposal.

As the component with the highest economic value in lithium-ion batteries, the recycling and reuse of cathode materials has always been one of the core technologies that receive the most attention. my country's nickel, cobalt, and lithium metal resources account for 2.1%, 1.84%, and 7.69% of the world's proven mining reserves respectively, and the grade of metal resources in used ternary lithium-ion batteries is much higher than that of raw ores mined. Therefore, the recycling and reuse of lithium-ion batteries is an inevitable trend for the sustainable development of the new energy industry. The ternary nickel-cobalt-manganese cathode material contains rich metal elements of Li, Ni, Co, and Mn, but the traditional recycling methods are mostly based on pyrometallurgy and hydrometallurgy processes, which simply regard waste lithium-ion batteries as A mixture containing a variety of metal elements makes it difficult to efficiently separate and recycle the various component resources. The pyrolysis recovery process is simple to operate and has a short process, but some metal resources are difficult to recover (lithium is partially present in the flue gas in the form of lithium oxide, and transition metals are present in the slag in the form of alloys), and the treatment process consumes high energy and pollutes the environment. Waste residue, smoke and waste gas, etc.; the wet process is represented by domestic companies such as Bump Cycle and GEM (CN116065033A, CN113802002A, CN111276767A, CN115505753A, etc.). The wet recovery process has a higher recovery rate of metal resources, and the impurity content of the final product is Low, higher purity, no need for high-temperature smelting, etc., but the wet process is complicated and requires the use of a large amount of acid and alkali reagents, and produces wastewater that requires further treatment.

Compared with these two processes, the repair and regeneration technology is a new solution based on the chemical composition and crystal structure characteristics of aging cathode materials. The decline in electrochemical performance of aging cathode materials is mainly attributed to the loss of active materials, reversible lithium loss and Loss of conductive properties, taking ternary nickel-cobalt-manganese materials as an example. During the cyclic aging process, some reversible lithium will form SEI films, lithium dendrites, etc. and become irreversible lithium. The layered crystal structure on the surface that facilitates the deintercalation of lithium ions will transform into resistance. With larger spinel structure and rock salt structure, the detachment and denaturation of the binder and conductive agent will cause the conductive performance to deteriorate. The repair and regeneration technology uses hydrothermal, molten salt, electrochemical and other methods to replenish lithium on the aged cathode material, and achieves the repair of the layered crystal structure under the induction of subsequent high-temperature sintering conditions. CN112670602A proposes a ternary cathode material regeneration and repair method based on hydrothermal lithium replenishment of LiOH solution and high-temperature calcination to repair the rock salt phase. This method does not need to cause damage to the structure of the cathode material, but coats the surface of the cathode material through a hydrothermal process. A layer of CEI film is formed, and reacts with _CO2 in the air during high-temperature calcination to generate lithium carbonate molten salt, thereby repairing the rock salt phase on the surface of the cathode material. However, this method requires the use of high-concentration LiOH solution (2-4 mol/L) and hydrothermal reaction under high pressure conditions, which has certain safety risks, and the calcination temperature and time need to rely on expensive transmission electron microscopy to measure the thickness of the CEI film. Sure. CN116216794A proposes a method for recycling and regenerating hexagonal prism single crystal ternary cathode materials for lithium ion batteries. The method involves sintering a certain amount of lithium salt and waste ternary cathode materials in an oxygen atmosphere, and then crushing, screening, and water-dissolving the ternary cathode materials. The dried cathode material is mixed with a small amount of lithium salt again and sintered to obtain a hexagonal prism-shaped single crystal ternary cathode material with crystal plane advantageous growth. This method does not require the high-pressure reaction conditions of the hydrothermal process, but the lithium salts used have higher melting points, such as LiOH (462°C), Li ₂ CO ₃ (720°C), and Li ₂ SO ₄ (859°C). Therefore, supplementing lithium requires The required primary sintering temperature is between 300 and 1300°C. Compared with the hydrothermal method, the energy consumption is higher and the sintering time is longer (10h).

Based on the above analysis of existing technologies, the microscopic mechanism of the repair process of aged cathode materials is complex. How to improve the repair method to achieve the goal of lower temperature and shorter process recycling is still a current technical problem.

Contents of the invention

The purpose of the present invention is to provide a method for repairing and regenerating waste lithium-ion battery cathode materials, so as to solve the problem of lithium replenishment at higher sintering temperatures and longer sintering times in the prior art.

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

The invention provides a method for repairing and regenerating waste lithium-ion battery cathode materials, which includes the following steps:

(1) Ball mill the aged cathode materials of used lithium-ion batteries to obtain single-particle cathode materials;

(2) Mix the single-particle cathode material and the lithium-rich salt mixture and then sinter once to obtain a lithium-supplemented single-particle cathode material;

(3) Mix the lithium-replenished single-particle cathode material and the lithium compound and perform secondary sintering to obtain a repaired single-crystal cathode material.

Preferably, in the step (1), the ball-to-material ratio of the ball milling treatment is 1 to 3:1, the rotation speed is 4000 to 6000 rpm, and the time is 3 to 15 minutes.

Preferably, in the step (2), the lithium-rich salt mixture is a mixture of two or more of lithium chloride, potassium chloride, aluminum chloride and lithium carbonate; the single particle cathode material and the lithium-rich salt mixture are The molar ratio of the salt mixture is 1:3~5.

Preferably, the lithium-rich salt mixture is lithium chloride and aluminum chloride, wherein the molar ratio of lithium chloride and aluminum chloride is 3:1-2.

Preferably, in step (2), the temperature of primary sintering is 150-400°C and the time is 2-6 hours.

Preferably, in the step (3), the molar ratio of the lithium-replenished single-particle cathode material and the lithium compound is 100:4-6.

Preferably, in step (3), the lithium compound includes one or more of lithium chloride, lithium nitrate, lithium hydroxide and lithium carbonate.

Preferably, in the step (3), the temperature of secondary sintering is 600-1000°C and the time is 6-10 hours.

Beneficial effects of the present invention:

(1) The present invention ball-mills aged cathode materials to obtain single-particle cathode materials. On the one hand, it increases the specific surface area of the cathode material and ensures that subsequent lithium replenishment and crystal repair are more uniform. On the other hand, it also obtains good Repair and regeneration of cathode materials with single crystal morphology.

(2) The present invention uses a multi-component lithium-rich salt mixture and the aged cathode material to mix, without the need to precisely control the amount of lithium supplement required to repair the cathode material, and to perform self-limiting lithium supplementation of the cathode material. The purpose of melting lithium can be achieved at a lower temperature. This operation does not require high temperature and high pressure, which is safer and consumes less energy.

(3) The present invention can achieve the purpose of repairing the transformation of the surface crystal structure from rock salt phase and spinel phase to layered after secondary sintering of lithium-replenished single particle cathode materials, and obtain regenerated cathode materials with good electrochemical properties. This set of process flow is short and the investment cost is low, which is convenient for large-scale industrial application.

Description of the drawings

Figure 1 is an SEM image of the single particle cathode material of Example 1;

Figure 2 is an SEM image of the single particle cathode material of Example 2;

Figure 3 is an SEM image of the single particle cathode material of Example 3;

Figure 4 is an SEM image of the single particle cathode material of Example 4;

Figure 5 is an SEM image of the single particle cathode material of Example 5;

Figure 6 is an SEM image of the single particle cathode material supplemented with lithium in Example 5;

Figure 7 is an SEM image of the repaired single crystal cathode material in Example 5;

Figure 8 is an XRD pattern of the aged cathode material and the repaired single crystal cathode material in Example 5;

Figure 9 is a 0.5C charge-discharge cycle curve of a button half-cell reassembled with the repaired single crystal cathode material in Example 5.

Detailed ways

The invention provides a method for repairing and regenerating waste lithium-ion battery cathode materials, which includes the following steps:

(1) Ball mill the aged cathode materials of used lithium-ion batteries to obtain single-particle cathode materials;

(2) Mix the single-particle cathode material and the lithium-rich salt mixture and then sinter once to obtain a lithium-supplemented single-particle cathode material;

(3) Mix the lithium-replenished single-particle cathode material and the lithium compound and perform secondary sintering to obtain a repaired single-crystal cathode material.

In the present invention, the method for processing aged positive electrode materials of used lithium-ion batteries includes the following steps:

S1: Completely discharge the used lithium-ion battery and then disassemble it to obtain the positive electrode piece;

S2: Mix the positive electrode piece and the organic solvent and then peel, sieve, centrifuge, and dry in sequence to obtain the aged positive electrode material of the used lithium-ion battery.

In the present invention, in step S1, it is preferred to soak the used lithium-ion battery in a salt solution for complete discharge. The soaking time is 0.5 to 6 hours, preferably 1 to 5 hours, and further preferably 2 to 4 hours.

The salt solution preferably used in the present invention is a zinc acetate solution, a ferrous sulfate solution or a zinc sulfate solution, and is further preferably a zinc acetate solution, wherein the concentration of the salt solution is 0.5 to 1 mol/L, preferably 0.5 mol/L, 0.8 mol/L, 1 mol/L, and more preferably 0.5 mol/L.

In the present invention, in the step S1, during disassembly, the waste lithium-ion battery is disassembled into battery positive electrode pieces, negative electrode pieces, separators, shells and other accessories, and the positive electrode pieces are taken out.

In the present invention, in the step S2, it is preferable to rinse the positive electrode piece with dimethyl carbonate and then dry it naturally.

In the present invention, the purpose of using dimethyl carbonate to rinse the positive electrode plate is to remove the electrolyte remaining on the surface of the electrode plate.

In the present invention, in step S2, the solid-liquid ratio of the positive electrode piece and the organic solvent is 1g:8-12mL, preferably 1g:9-11mL, and further preferably 1g:10mL.

In the present invention, the organic solvent includes γ-valerolactone, dihydro-glucosone or isosorbide dimethyl ether, preferably γ-valerolactone or isosorbide dimethyl ether, and further preferably γ-valerolactone or isosorbide dimethyl ether. lactone.

In the present invention, in the step S2, the positive electrode plate and the organic solvent are mixed and then the temperature is raised to 60-100°C, preferably 70-90°C, and more preferably 80°C.

In the present invention, in the step S2, peeling is performed under ultrasonic conditions, where the ultrasonic power is 90-150W, preferably 100-140W, preferably 110-130W, and the ultrasonic time is 2-10min, preferably 3~ 9 min, more preferably 4 to 8 min.

In the present invention, in step S2, the solid-liquid mixture obtained by stripping is passed through a 5-mesh sieve, the aluminum foil is removed, and then centrifugal separation is performed, wherein the rotation speed of the centrifugal separation is 5000 to 8000 rpm, preferably 5500 to 7500 rpm, preferably 5500 to 7500 rpm. 6000-7000 rpm, centrifugal separation time is 2-10 min, preferably 3-9 min, more preferably 4-8 min.

In the present invention, the lower positive electrode material precipitate obtained through centrifugal separation is washed, dried, and screened sequentially to obtain the aged positive electrode material of the waste lithium-ion battery.

In the present invention, the state of health (SOH) of the aged positive electrode material of the used lithium ion battery is 50 to 80%.

In the present invention, in the step (1), zirconium oxide is used for ball milling, wherein the particle size of zirconium oxide is 0.5 to 1.5 mm, preferably 1.0 mm.

In the present invention, in the step (1), the ball-to-material ratio of the ball milling process is 1 to 3:1, preferably 2:1; the rotation speed is 4000 to 6000rpm, preferably 4500 to 5500rpm, and further preferably 5000rpm; time It is 3-15min, Preferably it is 3min, 6min, 9min, 12min, 15min, More preferably, it is 9min, 12min, 15min.

In the present invention, in step (2), the lithium-rich salt mixture is a mixture of two or more of lithium chloride, potassium chloride, aluminum chloride and lithium carbonate; the single particle cathode material and The molar ratio of the lithium-rich salt mixture is 1:3-5, preferably 1:3, 1:4 or 1:5.

In the present invention, the lithium-rich salt mixture is preferably lithium chloride and aluminum chloride, wherein the molar ratio of lithium chloride and aluminum chloride is 3:1-2, preferably 3:2.

The present invention uses a lithium-rich salt mixture. When the lithium-rich salt mixture is mixed with AlCl ₃ and LiCl, the melting point of LiCl solid is 605°C and the melting point of AlCl ₃ solid is 194°C. The two substances are mixed according to a certain molar ratio. Forming a eutectic mixture, the melting point is lower than the melting point of a single pure phase material. Under 1bar pressure, when the molar ratio of AlCl ₃ to LiCl is 2:3, the melting point of the lithium-rich salt mixture is as low as 110°C, and AlCl ₃ is Covalent compounds exist in the molten state in the form of covalent dimer molecules (Al ₂ Cl ₆ ), which are easily hygroscopic in the air, and become acidic after partial hydrolysis of aluminum ions. Mixing the aged cathode material of used lithium-ion batteries with the AlCl ₃ -LiCl system can achieve the purpose of melting and replenishing lithium at 150-400°C. This operation does not require high temperature and high pressure, and is safer and lower energy consumption. The repair and regeneration method of the present invention does not require precise control of the amount of lithium supplement required when repairing the positive electrode material, and performs self-limiting lithium supplementation on the positive electrode material.

In the present invention, in the step (2), the temperature of primary sintering is 150-400°C, preferably 200-300°C, and further preferably 200°C; the time is 2-6h, preferably 2h, 3h, 4h, 5h, 6h, more preferably 2h, 3h, 4h.

In the present invention, in the step (3), the molar ratio of the lithium-replenished single particle cathode material and the lithium compound is 100:4-6, preferably 100:5.

In the present invention, in step (3), the lithium compound includes one or more of lithium chloride, lithium nitrate, lithium hydroxide and lithium carbonate, preferably one or more of lithium chloride, lithium hydroxide and lithium carbonate. One or more of them are further preferably lithium hydroxide and/or lithium carbonate.

In the present invention, in the step (3), the temperature of secondary sintering is 600-1000°C, preferably 700-900°C, and further preferably 800°C; the time is 6-10h, preferably 6h, 7h, 8h , 9h, 10h, more preferably 6h, 7h, 8h.

In the present invention, the primary sintering and secondary sintering are both carried out by microwave heating. During microwave heating, the temperature rise rate is 5 to 10°C/min, preferably 6 to 9°C/min, and further preferably 7 to 9°C/min. 8℃/min. When performing microwave heating in the present invention, a microwave tube furnace is preferably used, in which the microwave frequency is 2.45GHz and the microwave output power is continuously adjustable from 0.01 to 1.40kW.

The present invention uses microwave heating to significantly shorten the repair and regeneration time of aging cathode materials of used lithium-ion batteries.

The technical solutions provided by the present invention will be described in detail below with reference to the examples, but they should not be understood as limiting the protection scope of the present invention.

Example 1

Soak the used Li ₁ Ni _0.5 Co _0.2 Mn _0.3 O ₂ (NCM523) lithium ion battery in 0.5mol/L zinc acetate solution for 6 hours, discharge it completely to 0V, manually disassemble and sort out the positive electrode piece, use 200mL Use dimethyl carbonate (DMC) to clean the remaining electrolyte on the surface of the positive electrode sheet, dry it naturally and wait for subsequent operations.

Cut the positive electrode piece into a 100*100mm square, mix it with γ-valerolactone according to the solid-liquid ratio of 1g:10mL, then raise the temperature to 80°C, peel it off under 120W ultrasonic conditions for 10 minutes, and then pass the solid-liquid mixture through a 5-mesh sieve. Use a net to remove the aluminum foil, and finally centrifuge at 8000 rpm for 10 minutes to remove the lower cathode material precipitate, dry it in a vacuum oven at 100°C for 12 hours, and pass through a 120-mesh sieve to obtain the aged cathode material of the used lithium-ion battery.

The aged cathode material of the used lithium ion battery and the zirconia grinding beads with a diameter of 1 mm are mixed at a mass ratio of 2:1, and then placed in a high-speed micro-vibration ball mill for ball milling at a speed of 5000 rpm for 3 minutes to obtain a single particle cathode material; then the single particles are The granular positive electrode material and the lithium-rich salt mixture (the lithium-rich salt mixture is composed of LiCl and AlCl ₃ at a molar ratio of 3:2) are mixed evenly in an agate mortar at a molar ratio of 1:3, and then placed in a microwave tube One-time sintering is performed in a type furnace under an oxygen atmosphere, with a heating rate of 5°C/min, a temperature of 150°C, and a sintering time of 2 hours. After natural cooling to room temperature, it is washed three times with deionized water, and finally dried in a vacuum drying oven. After drying at 100°C for 12 hours, a lithium-replenished single particle cathode material was obtained.

Mix the lithium-supplemented single-particle cathode material and Li ₂ CO ₃ evenly at a molar ratio of 100:5, and then put it into a microwave tube furnace for secondary sintering in an oxygen atmosphere, where the heating rate is 5°C/min and the temperature is 800°C, the secondary sintering time is 6 hours, and after sintering, it is naturally cooled to room temperature to obtain the repaired single crystal cathode material.

Example 2

Soak the used Li ₁ Ni _0.5 Co _0.2 Mn _0.3 O ₂ (NCM523) lithium ion battery in 0.5mol/L zinc acetate solution for 6 hours, discharge it completely to 0V, manually disassemble and sort out the positive electrode piece, use 200mL Use dimethyl carbonate (DMC) to clean the remaining electrolyte on the surface of the positive electrode sheet, dry it naturally and wait for subsequent operations.

Cut the positive electrode piece into a 100*100mm square, mix it with γ-valerolactone according to the solid-liquid ratio of 1g:10mL, then raise the temperature to 80°C, peel it off under 120W ultrasonic conditions for 10 minutes, and then pass the solid-liquid mixture through a 5-mesh sieve. Use a net to remove the aluminum foil, and finally centrifuge at 8000 rpm for 10 minutes to remove the lower cathode material precipitate, dry it in a vacuum oven at 100°C for 12 hours, and pass through a 120-mesh sieve to obtain the aged cathode material of the used lithium-ion battery.

The aged cathode material of the used lithium ion battery and the zirconia grinding beads with a diameter of 1mm are mixed at a mass ratio of 2:1, and then placed in a high-speed micro-vibration ball mill for ball milling at a speed of 5000rpm for 6 minutes to obtain a single particle cathode material; then the single particles are The granular positive electrode material and the lithium-rich salt mixture (the lithium-rich salt mixture is composed of LiCl and AlCl ₃ at a molar ratio of 3:2) are mixed evenly in an agate mortar at a molar ratio of 1:3, and then placed in a microwave tube One-time sintering is performed in a type furnace under an oxygen atmosphere, with a heating rate of 10°C/min, a temperature of 200°C, and a sintering time of 2 hours. After natural cooling to room temperature, it is washed three times with deionized water, and finally dried in a vacuum drying oven. After drying at 100°C for 12 hours, a lithium-replenished single particle cathode material was obtained.

Mix the lithium-supplemented single-particle cathode material and Li ₂ CO ₃ evenly at a molar ratio of 100:5, and then put it into a microwave tube furnace for secondary sintering in an oxygen atmosphere, where the heating rate is 10°C/min and the temperature is 800°C, the secondary sintering time is 6 hours, and after sintering, it is naturally cooled to room temperature to obtain the repaired single crystal cathode material.

Example 3

The difference between Example 3 and Example 2 is that the ball milling time is 9 minutes, and other conditions are the same.

Example 4

Soak the used Li ₁ Ni _0.5 Co _0.2 Mn _0.3 O ₂ (NCM523) lithium ion battery in 0.5mol/L zinc acetate solution for 6 hours, discharge it completely to 0V, manually disassemble and sort out the positive electrode piece, use 200mL Use dimethyl carbonate (DMC) to clean the remaining electrolyte on the surface of the positive electrode sheet, dry it naturally and wait for subsequent operations.

Cut the positive electrode piece into a 100*100mm square, mix it with γ-valerolactone according to the solid-liquid ratio of 1g:10mL, then raise the temperature to 80°C, peel it off under 120W ultrasonic conditions for 10 minutes, and then pass the solid-liquid mixture through a 5-mesh sieve. Use a net to remove the aluminum foil, and finally centrifuge at 8000 rpm for 10 minutes to remove the lower cathode material precipitate, dry it in a vacuum oven at 100°C for 12 hours, and pass through a 120-mesh sieve to obtain the aged cathode material of the used lithium-ion battery.

The aged cathode material of the used lithium ion battery and the zirconia grinding beads with a diameter of 1mm are mixed at a mass ratio of 2:1, and then placed in a high-speed micro-vibration ball mill for ball milling at a speed of 5000rpm for 12 minutes to obtain a single particle cathode material; then the single particle cathode material is obtained. The granular cathode material and the lithium-rich salt mixture (the lithium-rich salt mixture is composed of LiCl and AlCl ₃ at a molar ratio of 3:2) are mixed evenly in an agate mortar at a molar ratio of 1:5, and then placed in a microwave tube One-time sintering is performed in a type furnace under an oxygen atmosphere, with a heating rate of 10°C/min, a temperature of 200°C, and a sintering time of 2 hours. After natural cooling to room temperature, it is washed 6 times with deionized water, and finally dried in a vacuum drying oven. After drying at 100°C for 12 hours, a lithium-replenished single particle cathode material was obtained.

Mix the lithium-supplemented single-particle cathode material and Li ₂ CO ₃ evenly at a molar ratio of 100:5, and then put it into a microwave tube furnace for secondary sintering in an oxygen atmosphere, where the heating rate is 10°C/min and the temperature is 900°C, the secondary sintering time is 6 hours, and after sintering, it is naturally cooled to room temperature to obtain the repaired single crystal cathode material.

Example 5

Soak the used Li ₁ Ni _0.5 Co _0.2 Mn _0.3 O ₂ (NCM523) lithium ion battery in 0.5mol/L zinc acetate solution for 6 hours, discharge it completely to 0V, manually disassemble and sort out the positive electrode piece, use 200mL Use dimethyl carbonate (DMC) to clean the remaining electrolyte on the surface of the positive electrode sheet, dry it naturally and wait for subsequent operations.

Cut the positive electrode piece into a 100*100mm square, mix it with γ-valerolactone according to the solid-liquid ratio of 1g:10mL, then raise the temperature to 80°C, peel it off under 120W ultrasonic conditions for 10 minutes, and then pass the solid-liquid mixture through a 5-mesh sieve. Use a net to remove the aluminum foil, and finally centrifuge at 8000 rpm for 10 minutes to remove the lower cathode material precipitate, dry it in a vacuum oven at 100°C for 12 hours, and pass through a 120-mesh sieve to obtain the aged cathode material of the used lithium-ion battery.

The aged cathode material of the used lithium-ion battery and the zirconia grinding beads with a diameter of 1mm are mixed at a mass ratio of 2:1, and then placed in a high-speed micro-vibration ball mill for ball milling at a speed of 5000rpm for 15 minutes to obtain a single particle cathode material; then the single particles are The granular cathode material and the lithium-rich salt mixture (the lithium-rich salt mixture is composed of LiCl and AlCl ₃ at a molar ratio of 3:2) are mixed evenly in an agate mortar at a molar ratio of 1:5, and then placed in a microwave tube One-time sintering is performed in a type furnace under an oxygen atmosphere, with a heating rate of 10°C/min, a temperature of 200°C, and a sintering time of 2 hours. After natural cooling to room temperature, it is washed 6 times with deionized water, and finally dried in a vacuum drying oven. After drying at 100°C for 12 hours, a lithium-replenished single particle cathode material was obtained.

Mix the lithium-supplemented single-particle cathode material and Li ₂ CO ₃ evenly at a molar ratio of 100:5, and then put it into a microwave tube furnace for secondary sintering in an oxygen atmosphere, where the heating rate is 10°C/min and the temperature is 900°C, the secondary sintering time is 8 hours, and after sintering, it is naturally cooled to room temperature to obtain the repaired single crystal cathode material.

Example 6

Soak the used Li ₁ Ni _0.5 Co _0.2 Mn _0.3 O ₂ (NCM523) lithium ion battery in 1mol/L ferrous sulfate solution for 4 hours, discharge it completely to 0V, manually disassemble and separate the positive electrode pieces, use 200mL Use dimethyl carbonate (DMC) to clean the remaining electrolyte on the surface of the positive electrode sheet, dry it naturally and wait for subsequent operations.

Cut the positive electrode piece into a 100*100mm square, mix it with isosorbide dimethyl ether according to the solid-liquid ratio of 1g:12mL, then heat it up to 100°C, peel it off under 90W ultrasonic conditions for 5 minutes, and then pass the solid-liquid mixture through 5 mesh The aluminum foil is removed through a sieve, and finally centrifuged at a speed of 5000 rpm for 5 minutes to remove the lower cathode material precipitate, dried in a vacuum oven at 100°C for 12 hours, and passed through a 120-mesh sieve to obtain the aged cathode material of the used lithium-ion battery.

The aged cathode material of the used lithium ion battery and the zirconia grinding beads with a diameter of 0.5mm are mixed at a mass ratio of 1:1, and then placed in a high-speed micro-vibration ball mill for ball milling at a speed of 4000rpm for 15 minutes to obtain a single particle cathode material; then The single particle cathode material and the lithium-rich salt mixture (the lithium-rich salt mixture is composed of LiCl and AlCl ₃ at a molar ratio of 3:2) are mixed evenly in an agate mortar at a molar ratio of 1:5, and then placed in the microwave A primary sintering is performed in a tube furnace under an oxygen atmosphere, with a heating rate of 10°C/min, a temperature of 400°C, and a sintering time of 2 hours. After natural cooling to room temperature, it is washed 6 times with deionized water, and finally placed in a vacuum drying box. After drying at 100°C for 12 hours, a lithium-replenished single particle cathode material was obtained.

Mix the lithium-supplemented single-particle cathode material and lithium nitrate evenly at a molar ratio of 100:6, then place it into a microwave tube furnace for secondary sintering in an oxygen atmosphere, with a heating rate of 10°C/min and a temperature of 600°C. , the secondary sintering time is 10h, and after sintering, it is naturally cooled to room temperature to obtain the repaired single crystal cathode material.

Example 7

Soak the used Li ₁ Ni _0.5 Co _0.2 Mn _0.3 O ₂ (NCM523) lithium ion battery in 0.8mol/L zinc sulfate solution for 6 hours, discharge it completely to 0V, manually disassemble and separate the positive electrode pieces, use 200mL Use dimethyl carbonate (DMC) to clean the remaining electrolyte on the surface of the positive electrode sheet, dry it naturally and wait for subsequent operations.

Cut the positive electrode piece into a 100*100mm square, mix it with dihydroglucosone at a solid-liquid ratio of 1g:8mL, then heat it up to 60°C, peel it off under 150W ultrasonic conditions for 8 minutes, and then pass the solid-liquid mixture through a 5-mesh sieve. Use a net to remove the aluminum foil, and finally centrifuge at 7000 rpm for 8 minutes to remove the lower cathode material precipitate, dry it in a vacuum oven at 100°C for 12 hours, and pass through a 120-mesh sieve to obtain the aged cathode material of the spent lithium-ion battery.

The aged cathode material of the used lithium-ion battery and the zirconia grinding beads with a diameter of 1.5mm are mixed at a mass ratio of 3:1, and then placed in a high-speed micro-vibration ball mill for ball milling at 6000rpm for 10 minutes to obtain a single particle cathode material; then The single particle cathode material and the lithium-rich salt mixture (the lithium-rich salt mixture is composed of LiCl and AlCl ₃ at a molar ratio of 3:1) are mixed evenly in an agate mortar at a molar ratio of 1:4, and then placed in the microwave A primary sintering is performed in a tube furnace under an oxygen atmosphere, with a heating rate of 8°C/min, a temperature of 300°C, and a primary sintering time of 3 hours. After natural cooling to room temperature, it is washed 6 times with deionized water, and finally placed in a vacuum drying oven. After drying at 100°C for 12 hours, a lithium-replenished single particle cathode material was obtained.

Mix the lithium-supplemented single-particle cathode material and lithium hydroxide evenly at a molar ratio of 100:4, then place it into a microwave tube furnace for secondary sintering in an oxygen atmosphere, with a heating rate of 8°C/min and a temperature of 1000 ℃, the secondary sintering time is 7 hours, and after sintering, it is naturally cooled to room temperature to obtain the repaired single crystal cathode material.

Performance verification:

The single crystal cathode material repaired in Example 5, the binder PVDF, and the conductive agent acetylene black were mixed and slurried with 2.5 mL NMP solvent in a mass ratio of 0.8g:0.1g:0.1g, and then evenly coated on the aluminum foil, and placed After drying in a vacuum oven at 80°C overnight, use a punching machine to cut out positive electrode sheets with a diameter of 14mm, and assemble them with a commercial electrolyte of 1mol/L LiPF ₆ + EC:DEC (1:1wt%) and a lithium sheet negative electrode. CR2032 button battery and tested its charge and discharge performance. The results are shown in Figure 9.

It can be seen from Figures 1 to 5 that a high-speed micro-vibration ball mill requires a processing time of more than 9 minutes at a rotation speed of 5000 rpm to obtain single-particle cathode materials with good dispersion.

It can be seen from Figures 6 and 7 that under the operating conditions of Example 5, the cathode material after one-time sintering of AlCl ₃ -LiCl and lithium replenishment showed a single-particle micromorphology with sharp edges and cracks and damage on the crystal surface, but The repaired single-crystal cathode material obtained after secondary sintering shows a good smooth-edged single-crystal morphology, with mostly particles in the range of 1 to 3 μm in size, good dispersion, and no cracks on the surface.

It can be seen from Figure 8 that the crystal structure of the repaired single crystal cathode material of Example 5 has been significantly restored compared with the aged cathode material that has not been repaired. This can also be seen from Figure 9. When the single crystal cathode material repaired in Example 5 is reassembled into a button half cell, its initial discharge specific capacity can reach 157mAh/g. After 70 cycles of 0.5C charge and discharge cycles, the discharge specific capacity is still Higher than 140mAh/g, indicating that the electrochemical performance of the repaired cathode material has been improved. This repair and regeneration method greatly simplifies the recycling and reuse process of used cathode materials, and has significant advantages of low energy consumption and high safety.

As can be seen from the above embodiments, the present invention provides a method for repairing and regenerating waste lithium-ion battery cathode materials. The present invention first ball-mills the aged cathode materials of waste lithium-ion batteries to obtain single-particle cathode materials; and then grinds the single-particle cathode materials. It is mixed with a lithium-rich salt mixture and then sintered once to obtain a lithium-supplemented single-particle cathode material; finally, the lithium-supplemented single-particle cathode material is mixed with a lithium compound and then sintered twice to obtain a repaired single-crystal cathode material. The present invention uses a multi-component lithium-rich salt mixture and aged cathode materials to mix. It does not need to precisely control the amount of lithium supplement required to repair the cathode material. The purpose of melting lithium supplement can be achieved at a lower temperature. This operation does not require high temperature and high pressure. , safer and lower energy consumption.

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

Claims (8)

1. A method for repairing and regenerating waste lithium-ion battery cathode materials, which is characterized in that it includes the following steps: (1) Ball mill the aged cathode materials of used lithium-ion batteries to obtain single-particle cathode materials; (2) Mix the single-particle cathode material and the lithium-rich salt mixture and then sinter once to obtain a lithium-supplemented single-particle cathode material; (3) Mix the lithium-replenished single-particle cathode material and the lithium compound and perform secondary sintering to obtain a repaired single-crystal cathode material. 2. The repair and regeneration method according to claim 1, characterized in that in the step (1), the ball-to-material ratio of the ball milling process is 1 to 3:1, the rotation speed is 4000 to 6000 rpm, and the time is 3 to 15 minutes. 3. The repair and regeneration method according to claim 1 or 2, characterized in that in the step (2), the lithium-rich salt mixture is two kinds of lithium chloride, potassium chloride, aluminum chloride and lithium carbonate. Or a mixture of two or more; the molar ratio of the single particle cathode material and the lithium-rich salt mixture is 1:3-5. 4. The repair and regeneration method according to claim 3, wherein the lithium-rich salt mixture is lithium chloride and aluminum chloride, and the molar ratio of lithium chloride and aluminum chloride is 3:1-2. 5. The repair and regeneration method according to claim 1 or 2 or 4, characterized in that in the step (2), the temperature of primary sintering is 150-400°C and the time is 2-6 hours. 6. The repair and regeneration method according to claim 5, characterized in that in the step (3), the molar ratio of the lithium-supplemented single-particle cathode material and the lithium compound is 100:4-6. 7. The repair and regeneration method according to claim 2 or 6, characterized in that in the step (3), the lithium compound contains one or more of lithium chloride, lithium nitrate, lithium hydroxide and lithium carbonate. . 8. The repair and regeneration method according to claim 7, characterized in that in the step (3), the temperature of the secondary sintering is 600-1000°C and the time is 6-10 hours.