Method for separating components in solid waste of retired power battery by using supercritical ethanol

Abstract

The invention discloses a method for separating components in solid waste of a decommissioned power battery by using supercritical ethanol, which comprises the following steps of: firstly, soaking the decommissioned power battery in a sodium chloride solution for chemical discharge, removing a battery shell after the discharge is completed, and separating a battery core; grinding the battery cell into particle powder with a certain size, putting the particle powder and absolute ethyl alcohol into an intermittent reaction kettle, sealing, and purging with nitrogen; heating the ethanol to a supercritical state, and staying for a certain time; and separating positive and negative electrode materials and an organic liquid phase in a suction filtration manner, washing to obtain a pure positive electrode material and graphite, and carrying out rotary evaporation on the organic liquid phase to separate and recover an organic solvent and ethanol. The recovered organic solvent and lithium salt can be prepared into an electrolyte solution, and ethanol can be continuously put into the reaction kettle for recycling. The invention provides an efficient, green and environment-friendly method for pretreatment and high-value utilization of the retired power battery, and the method has a good application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste resource treatment, and particularly relates to a method for separating components in waste power batteries by using supercritical ethanol. Background Art

[0002] The global energy structure is gradually transforming, and the demand for renewable energy is also increasing day by day. The electric vehicle (EV) industry in China has developed rapidly. Power batteries are the most core components of electric vehicles. From January to November 2024, according to statistics, the cumulative output of power and other batteries in China reached 965.3 GWh, with a cumulative year-on-year growth of 37.7%. By the end of 2024, the cumulative output of power and other batteries in China will exceed 1 TWh. In terms of the number of installed vehicles, the cumulative installed capacity of power batteries in China was 473.0 GWh, with a cumulative year-on-year growth of 39.2%. Among them, the cumulative installed capacity of ternary batteries was 124.7 GWh, accounting for 26.4% of the total installed capacity; the cumulative installed capacity of lithium iron phosphate batteries was 348.0 GWh, accounting for 73.6% of the total installed capacity. Thus, it can be seen that the demand for power batteries is extremely large. However, the lifespan of power batteries is limited, and they will be retired after a certain number of charge-discharge cycles. If not properly treated, it will pose a great threat to the environment. Data shows that it is estimated that by 2025, more than 19.5 million new energy vehicles in China will have their battery warranty periods of more than 8 years expired; at the same time, the amount of retired power batteries will reach 820,000 tons, which means that the power batteries of hundreds of thousands of electric vehicles will no longer be used. Therefore, the recycling and resource utilization of retired power batteries are urgent problems to be solved.

[0003] In order to better recycle and resource-utilize retired power batteries, separating and extracting organic and inorganic components are key steps in the pretreatment process of retired power batteries. The electrolyte solution of power batteries usually includes various organic solvents (such as carbonate compounds) and lithium salts (such as LiFP 6 )). Traditional separation methods include high-temperature roasting or chemical reagent washing, which often have problems such as high energy consumption, low separation efficiency, and environmental pollution. For example, high-temperature roasting usually requires a high temperature of 700°C, and the volatile gases are likely to cause great harm to human health. There is an urgent need to develop an efficient, clean, and environmentally friendly separation method.

[0004] Due to its unique physical and chemical properties, supercritical fluid technology has shown great potential for application in separating organic and inorganic components. Specifically, supercritical ethanol has characteristics such as adjustable solubility, high diffusivity, and low viscosity, and is an ideal choice for achieving efficient separation of organic and inorganic components. During the reaction process, supercritical ethanol can efficiently dissolve the organic substances in the battery cells, realizing the efficient separation of organic and inorganic components.

[0005] Specifically, by adjusting parameters such as temperature, solid-liquid ratio, and reaction time, supercritical ethanol can selectively dissolve organic solvents in power batteries, such as carbonate compounds, to achieve the recycling of electrolyte solutions. At the same time, the positive electrode materials are separated to fully prepare for the subsequent acid leaching process, ultimately realizing the recycling of positive electrode metal materials. This process not only improves the recycling rate of materials but also reduces the environmental impact of solvent usage. Another advantage is that supercritical ethanol can be separated and extracted by rotary evaporation in the liquid phase to achieve the recycling of solvents. Summary of the Invention

[0006] Aiming at the problems of high energy consumption in conventional pretreatment of retired power batteries, low separation efficiency of organic / inorganic components, and environmental pollution, the purpose of the present invention is to provide a method for separating components in retired power battery solid waste using supercritical ethanol, which uses supercritical ethanol to depolymerize olefin materials such as diaphragms, separates the positive and negative electrode materials, and simultaneously recovers organic solvents and lithium salts to form a green, pollution-free, and highly efficient recycling system.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is: a method for separating components in retired power battery solid waste using supercritical ethanol, comprising the following steps:

[0008] (1) Immerse the retired power battery monomer in a sodium chloride solution for 20 - 24 hours to fully discharge, and wipe dry the moisture on the battery surface;

[0009] (2) Remove the battery casing and retain the battery core;

[0010] (3) Subject the battery core to a precision grinding process to refine it to a fine particle state of 80 - 100 mesh to obtain battery core powder, and seal it for preservation to avoid volatilization of organic matter;

[0011] (4) Put all the battery core powder into an intermittent reaction kettle, add ethanol, seal it, and use an inert gas to purge the air in the sealed container;

[0012] (5) Raise the temperature of the intermittent reaction kettle until ethanol reaches the supercritical state, maintain it for 10 - 30 minutes, and then cool it to room temperature;

[0013] (6) Collect the gas products with a gas collection bag, and filter to separate the solid phase products and liquid phase products; wash the solid phase products with dichloromethane to obtain graphite and positive electrode materials; perform rotary evaporation on the liquid phase products to obtain the recycled ethanol and organic oil phase products.

[0014] Furthermore, in the step (1), the mass percentage of the sodium chloride solution is 10 - 15%, and the solid-liquid ratio is 1:20 (by mass).

[0015] Further, in the step (4), the time for purging the air in the sealed container with the inert gas is 10 min.

[0016] Further, in the step (4), the mass ratio of the cell powder to ethanol is 1:6.

[0017] Further, in the step (4), the inert gas is nitrogen.

[0018] Further, in the step (5), when the temperature rises to the supercritical state of ethanol, the heating rate is 5 - 10 °C / min, the reaction temperature is 260 - 300 °C, and the reaction pressure is 7 - 10 MPa.

[0019] Further, in the step (5), the cooling to room temperature specifically is: first, use a fan to blow and accelerate the cooling, cool down to 25 - 150 °C within 10 minutes, and then naturally cool to room temperature.

[0020] Further, in the step (6), the temperature for rotary evaporation of the liquid-phase product is 70 °C.

[0021] Further, in the step (6), the recovered ethanol is used to be re-added to the reaction kettle for reaction; the recovered organic matter in the oil phase is re-used for the preparation of the electrolyte solution for power batteries.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. The present invention can efficiently depolymerize olefin materials such as diaphragms, recover high-quality organic solvents, does not produce secondary pollution, and the recovered organic solvents can be re-used for the preparation of electrolyte solutions, realizing high-value utilization.

[0024] 2. The present invention uses ethanol as a solvent, which has a lower critical temperature and pressure compared with water, and ethanol itself is non-toxic, ensuring the safety of the reaction process. In the supercritical state, ethanol will undergo a dehydrogenation reaction, and the generated hydrogen radicals can effectively impact the macromolecular chain segments of the polymer, thereby being converted into oligomers to achieve efficient depolymerization of polymers such as diaphragms.

[0025] 3. After the reaction of the present invention is completed, ethanol can be separated from the organic solvent by rotary evaporation, and the recovered ethanol can be reused, having good economy.

[0026] 4. The present invention can better separate the organic and inorganic components in the battery, and the obtained inorganic components are relatively pure, which can improve the leaching efficiency of the subsequent acid leaching process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a flow chart of the present invention. Detailed implementation manners

[0028] In order to elaborate in detail the technical solutions adopted by the present invention to achieve the predetermined technical purposes, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the implementation manners of the present invention are not limited thereto.

[0029] As Figure 1 shown, an embodiment of the present invention provides a method for separating components in waste retired power batteries by using supercritical ethanol, and the specific steps are as follows:

[0030] S1. Immerse the waste retired power battery in a sodium chloride solution with a mass fraction of 10 - 15% for 20 - 24 h, where the ratio of the battery to the solution is 1:20.

[0031] S2. After soaking, dry the moisture on the surface of the battery, and remove the outer shell of the battery by manual crushing, leaving the battery core.

[0032] S3. Subject the battery core to a precision grinding process to refine it to a fine particle state meeting the 80 - 100 mesh standard, obtaining a precursor battery core powder, and seal it for storage to avoid volatilization of organic matter.

[0033] S4. Put the battery core powder and ethanol into a high - pressure reactor in a certain mass ratio, seal it, and purge it with nitrogen for 10 min to remove all the air in the sealed container, maintaining an anaerobic environment.

[0034] S5. Raise the temperature of ethanol to the supercritical state at a certain reaction heating rate. After reaching the reaction temperature and pressure (reaction temperature 250 - 300 °C, pressure 7.0 - 10 MPa), maintain the existing state for 10 - 30 min.

[0035] S6. After the reaction is completed, first accelerate the cooling, cool the inside of the reactor to 25 - 150 °C within 10 minutes, and then naturally cool it to room temperature.

[0036] S7. After cooling is completed, collect the gas product with a gas collection bag, and separate the solid - phase product and the liquid - phase product by suction filtration; wash the solid - phase product with dichloromethane to obtain graphite and the positive electrode material; perform rotary evaporation on the liquid - phase product to obtain the recovered ethanol and the organic oil - phase product.

[0037] Example 1

[0038] S1. Take a waste retired lithium battery, weigh 44.0106 g, and immerse it in a sodium chloride solution with a mass fraction of 10% for 24 h, with a solid - liquid mass ratio of 1:20.

[0039] S2. After soaking, dry the moisture on the surface of the battery, and remove the outer shell of the battery by manual crushing, leaving the battery core, weighing 30.2940 g.

[0040] S3. Subject the battery cell to a precision grinding process to refine it to a fine particle state meeting the 100-mesh standard, obtaining a precursor, and store it in a sealed manner.

[0041] S4. Put 30.2940 g of battery cell powder and 181.7640 g of absolute ethanol into an intermittent reactor at a ratio of 1:6, then strictly seal the reactor, and purge the container with nitrogen for 10 min to remove all the air inside the container, achieving an anaerobic environment.

[0042] S5. Raise the temperature inside the reactor to 260 °C at a heating rate of 10 °C / min, with a pressure of 8.5 MPa. After reaching the reaction temperature and pressure, maintain the current state for 20 min.

[0043] S6. After the reaction is completed, take the reactor out of the heating jacket, first use a fan to blow and accelerate the cooling, cool it to 25 - 150 °C within 10 min, and then perform natural cooling.

[0044] S7. After cooling is completed, collect the gas products with a gas collection bag, and separate the solid-phase products and liquid-phase products by suction filtration; wash the solid-phase products with dichloromethane to obtain graphite and cathode materials; perform rotary evaporation on the liquid-phase products at 60 °C to obtain the recovered ethanol and organic oil-phase products.

[0045] Under this working condition, the depolymerization rate of olefin materials such as the separator can reach 99.87%, 1.9176 g of organic solvents are recovered, and the recovery rate reaches 42.2%. The main products of the oil-phase products detected by Agilent 7890A / 5975C (GC-MS) gas chromatography - mass spectrometry are carbonate compounds, with a calorific value of up to 30.1 MJ / kg, and the recycling value is relatively high.

[0046] Example 2

[0047] S1. Take a retired lithium battery, weigh 41.5674 g, and soak it in a 10% sodium chloride solution by mass for 24 h, with a solid-liquid mass ratio of 1:20.

[0048] S2. After soaking, dry the moisture on the battery surface, and remove the outer shell of the battery by manual crushing, retaining the battery cell, and weigh 31.3289 g.

[0049] S3. Subject the battery cell to a precision grinding process to refine it to a fine particle state meeting the 100-mesh standard, obtaining a precursor, and store it in a sealed manner.

[0050] S4. Put 31.3289 g of battery cell powder and 125.3156 g of absolute ethanol into an intermittent reactor at a ratio of 1:4, then strictly seal the reactor, and purge the container with nitrogen for 10 min to remove all the air inside the container, achieving an anaerobic environment.

[0051] S5. Increase the temperature in the reaction kettle to 260 °C at a heating rate of 10 °C / min, with a pressure of 8.5 MPa. After reaching the reaction temperature and pressure, maintain the current state for 20 min.

[0052] S6. After the reaction is completed, take the reaction kettle out of the heating jacket. First, use an electric fan to blow for accelerated cooling, and cool down to 25 - 150 °C within 10 min, and then perform natural cooling.

[0053] S7. After cooling is completed, collect the gas products with a gas collection bag, and separate the solid-phase products and liquid-phase products by suction filtration; wash the solid-phase products with dichloromethane to obtain graphite and the cathode material; perform rotary evaporation on the liquid-phase products at 60 °C to obtain the recovered ethanol and organic oil-phase products.

[0054] Under this working condition, the depolymerization rate of olefin materials such as the separator can reach 99.75%, 1.5434 g of organic solvent is recovered, and the recovery rate reaches 39.9%. The main product of the oil-phase product detected by gas chromatography-mass spectrometry (Gas Chromatography-Mass Spectrometry) is carbonate compounds, and the calorific value can reach 30.1 MJ / kg, with relatively high recycling value.

[0055] Example 3

[0056] S1. Take a retired lithium battery, weigh 44.3595 g, and soak it in a 10% sodium chloride solution for 24 h, with a solid-liquid mass ratio of 1:20.

[0057] S2. After soaking, dry the moisture on the battery surface, and remove the battery surface shell by manual crushing, retaining the battery core, and weigh 34.4736 g.

[0058] S3. Subject the battery core to a precision grinding process to refine it to a fine particle state meeting the 100-mesh standard to obtain a precursor, and store it sealed.

[0059] S4. Put 34.4736 g of the battery core powder and 137.8944 g of absolute ethanol into an intermittent reaction kettle at a ratio of 1:4, then strictly seal the reaction kettle, and purge the container with nitrogen for 10 min to remove all the air in the container to achieve an anaerobic environment.

[0060] S5. Increase the temperature in the reaction kettle to 280 °C at a heating rate of 10 °C / min, with a pressure of 8.5 MPa. After reaching the reaction temperature and pressure, maintain the current state for 20 min.

[0061] S6. After the reaction is completed, take the reaction kettle out of the heating jacket. First, use an electric fan to blow for accelerated cooling, and cool down to 25 - 150 °C within 10 min, and then perform natural cooling.

[0062] After the cooling is completed, the gas collection bag collects the gas products, and the solid-phase product and the liquid-phase product are separated by suction filtration; the solid-phase product is washed with dichloromethane to obtain graphite and the cathode material; the liquid-phase product is rotary evaporated at 60 °C to obtain the recovered ethanol and the organic oil-phase product.

[0063] Under this working condition, the depolymerization rate of olefin materials such as the separator can reach 99.41%, 1.4529 g of the organic solvent is recovered, and the recovery rate reaches 38.7%. The main product of the oil-phase product detected by gas chromatography-mass spectrometry (Gas Chromatography-Mass Spectrometry) is carbonate compounds, and the calorific value can reach 30.1 MJ / kg, with high recycling value.

[0064] The present invention uses supercritical ethanol to depolymerize olefin materials such as the separator, separates the positive and negative inorganic materials, and at the same time recovers and utilizes the organic solvents in the electrolyte solution, realizing high-value utilization. In the supercritical state, ethanol will undergo a dehydrogenation reaction, and the generated hydrogen radicals can effectively impact the macromolecular chains of the polymer, thereby being converted into oligomers to achieve the depolymerization of polymers such as the separator, while graphite and metal oxides do not react. In the supercritical state, the low viscosity and high diffusivity of ethanol enable it to penetrate deep into the cell powder, carry the organic substances away from the solid matrix, and by adjusting the temperature and pressure, the organic substances can be separated in the form of an oil phase to achieve the separation, recovery and utilization of organic and inorganic components.

[0065] After considering the specification and the content disclosed herein, those skilled in the art will readily think of other embodiments of the present application. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include the common general knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and the embodiments are only regarded as exemplary.

[0066] It should be understood that the present application is not limited to the exact structures already described and shown in the drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A method for separating components from solid waste of retired power batteries using supercritical ethanol, characterized in that: The steps include: (1) Soak the retired power battery cells in sodium chloride solution for 20-24 hours to fully discharge them, and wipe off the moisture on the battery surface; (2) Remove the battery casing and keep the battery core; (3) subjecting the battery cell to a precision grinding process to be refined into a state of tiny particles of 80-100 meshes, obtaining a battery cell powder, and sealing and storing the powder to prevent the volatilization of organic matter; (4) Put all the battery core powder into an intermittent reactor, add ethanol, seal it, and use inert gas to purge and remove all the air in the sealed container; (5) raising the temperature of the intermittent reactor until the ethanol reaches a supercritical state, maintaining the temperature for 10-30 min, and then cooling to room temperature; (6) Collecting gaseous products with a gas collection bag and separating solid products and liquid products by suction filtration; The solid phase product is washed with dichloromethane to obtain graphite and positive electrode materials; the liquid phase product is subjected to rotary evaporation to obtain recovered ethanol and organic oil phase products.

2. The method for separating components from solid waste of retired power batteries using supercritical ethanol according to claim 1, characterized in that: In the step (1), the mass percentage of the sodium chloride solution is 10-15%, and the solid-liquid mass ratio is 1:

20.

3. The method for separating components from solid waste of retired power batteries using supercritical ethanol according to claim 1, characterized in that: In the step (4), the time for purging the air in the sealed container with inert gas is 10 minutes.

4. The method for separating components from solid waste of retired power batteries using supercritical ethanol according to claim 1, characterized in that: In the step (4), the mass ratio of the battery core powder to ethanol is 1:

6.

5. The method for separating components from solid waste of retired power batteries using supercritical ethanol according to claim 1, characterized in that: In the step (4), the inert gas is nitrogen.

6. The method for separating components from solid waste of retired power batteries using supercritical ethanol according to claim 1, characterized in that: In the step (5), the temperature is increased until the ethanol reaches a supercritical state, the heating rate is 5-10°C / min, the reaction temperature is 260-300°C, and the reaction pressure is 7-10MPa.

7. The method for separating components from solid waste of retired power batteries using supercritical ethanol according to claim 1, characterized in that: In the step (5), the cooling to room temperature is specifically as follows: firstly, a fan is used to blow to accelerate the cooling, the temperature is lowered to 25-150° C. within 10 minutes, and then naturally cooled to room temperature.

8. The method for separating components from solid waste of retired power batteries using supercritical ethanol according to claim 1, characterized in that: In the step (6), the temperature for rotary evaporation of the liquid product is 70°C.

9. The method for separating components from solid waste of retired power batteries using supercritical ethanol according to claim 1, characterized in that: In the step (6), the recovered ethanol is added back into the reactor for reaction; the recovered oil phase organic matter is reused in the preparation of the power battery electrolyte solution, and the oil phase organic matter includes propylene carbonate and ethylene carbonate.

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