Recovery method for selectively extracting lithium from retired lithium ion battery

Abstract

The invention relates to the field of retired lithium ion battery recovery, and discloses a method for selectively extracting lithium from a retired lithium ion battery, which comprises the following steps: putting the retired lithium ion battery and a certain amount of chlorine-containing material into a reactor for reaction to obtain a first reaction product, leaching the first reaction product to obtain a second reaction product; a second reaction product is obtained, a leaching agent is at least one of water and absolute ethyl alcohol, and the second reaction product is subjected to solid-liquid separation to obtain a lithium-containing solution and leaching residues. According to the method, the chlorine-containing material is creatively used for the thermal reduction process of the retired lithium ion battery, the subsequent selective leaching rate of lithium is effectively improved, harmless treatment and resource utilization of various chlorine-containing organic waste can be achieved, other chlorine-containing organic waste can be treated in the thermal reduction process of the battery, and the method is suitable for industrial production. And the problem of safe emission of chlorine is also solved.

Description

Technical Field

[0001] The present invention relates to the field of recycling retired lithium-ion batteries, and in particular to a recycling method for selectively extracting lithium from retired lithium-ion batteries. Background Art

[0002] Lithium-ion batteries (LIBs), with their exceptional properties such as high energy density, excellent rechargeability, and high voltage, play a vital role in the electric vehicle industry. In recent years, with the rapid development of the electric vehicle industry, the consumption of LIBs has increased dramatically. However, LIBs have a limited lifespan (typically 3–5 years), resulting in a large number of retired LIBs. Retired LIBs contain not only a large amount of precious metals such as lithium, cobalt, and nickel, but also a large number of toxic components such as binders, electrolytes, and separator materials, among other toxic organic compounds. Therefore, the efficient recovery and safe disposal of retired LIBs is of great strategic importance for environmental protection and sustainable resource utilization.

[0003] Currently, the recycling methods for retired lithium-ion batteries are mainly divided into two categories: pyrometallurgy and hydrometallurgy. Pyrometallurgical processes cannot effectively recover lithium and consume a large amount of energy. In contrast, hydrometallurgical processes have the advantages of simple operation, high lithium recovery efficiency, and good quality of recycled products, and have broad application prospects in practice. Traditional hydrometallurgical processes require a large amount of acid to leach retired lithium-ion battery waste. In order to improve the leaching efficiency of the target metal, a reducing agent must also be added during the leaching process. In addition, due to the excessive loss of lithium in the later stage of extraction and the low concentration of the residual liquid at the end of the solvent extraction stage, lithium recovery is difficult and the economic benefits are poor.

[0004] In recent years, many researchers have proposed a number of improved hydrometallurgical processes based on the concept of preferential lithium extraction to improve lithium recovery and reduce chemical reagent consumption. These include thermal reduction-leaching processes (CN115621597A, CN110541077A, and CN116240385A), electrochemical deintercalation (CN116445731A), selective leaching processes using unconventional leaching agents (CN116598636A and CN115161483A), and salt roasting conversion-leaching processes (CN118006927A and CN115367732A). Among these, thermal reduction-water leaching for selective lithium extraction is considered the most promising method. This process utilizes the chemical energy of reducing substances in the battery, such as graphite, organic matter, and aluminum. During the thermal reduction process, lithium is converted into water-soluble lithium carbonate, while nickel, cobalt, and manganese are converted into water-insoluble substances. After water leaching, selective lithium extraction can be achieved.

[0005] Therefore, the advantages of this process are: (1) it makes full use of the reducing substances contained in the battery itself without the need for external fuel or reducing agent; (2) the water immersion process does not produce waste water such as waste acid, is simple to operate, and is easy to industrialize; (3) the controllable thermal reduction process can also reduce the explosion safety risk of battery disassembly and crushing.

[0006] However, batteries inevitably contain a large amount of fluorine-containing substances, such as the positive electrode binder polyvinylidene fluoride (PVDF) and the electrolyte LiPF6. Since they are difficult to be effectively removed in advance, part of the lithium is converted into LiF, which is insoluble in water, during the thermal reduction process, which greatly reduces the lithium recovery rate during the leaching process, and ultimately makes this process difficult to apply industrially.

[0007] Therefore, there is an urgent need for a recovery method for selectively extracting lithium from retired lithium-ion batteries to solve the above technical problems. Summary of the Invention

[0008] The purpose of the present invention is to overcome the deficiencies mentioned in the above-mentioned background technology and provide a method for effectively improving the lithium recovery rate of the pyrolysis reduction-water leaching process of waste lithium-ion batteries. At the same time, it can also solve the problem of harmless disposal of chlorine-containing organic waste, and propose a recovery method for selectively extracting lithium from retired lithium-ion batteries.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: a recovery method for selectively extracting lithium from retired lithium-ion batteries, comprising the following steps: S1, putting retired lithium-ion batteries and a certain amount of chlorine-containing materials into a reactor to react to obtain a first reaction product, controlling the reaction temperature at 250°C to 1000°C, and the reaction time at the reaction temperature ≥ 15min; S2, leaching the first reaction product obtained in step S1 to obtain a second reaction product, wherein the leaching agent is at least one of water and anhydrous ethanol, the leaching temperature is 15° C. to 100° C., and the leaching time is ≥10 min; S3, performing solid-liquid separation on the second reaction product obtained in step S2 to obtain a lithium-containing solution and leached residue.

[0010] Preferably, the retired lithium-ion batteries are at least one of waste lithium-ion batteries, lithium-ion batteries with shells that have not been disassembled or crushed, materials containing lithium-ion battery positive electrode materials that have been physically sorted (disassembly, crushing, screening, etc.), unqualified lithium-ion battery positive electrode powder or pole pieces, a mixture of lithium-ion battery waste and cobalt-containing materials, and a mixture of lithium-ion battery waste and manganese-containing materials.

[0011] Specifically, the lithium-ion battery waste must at least include lithium-ion battery positive electrode materials.

[0012] Preferably, the retired lithium-ion battery contains one or more of cobalt, nickel, manganese and iron.

[0013] Preferably, the chlorine-containing material is at least one of plastics, rubber, resin, organic solution, organic polymer, and organic matter containing chlorine element.

[0014] Preferably, the mass ratio of the added amount of the chlorine-containing material to the retired lithium-ion battery is ≥2%.

[0015] Preferably, the added amount of the chlorine-containing material is 5% to 150% by mass of the retired lithium-ion battery.

[0016] Preferably, in step S1, the reactor is at least one of a pyrolysis furnace, a rotary kiln, a tunnel kiln, a roasting furnace, and a rotary kiln, and a carbon-containing material is added to the pyrolysis furnace. The carbon-containing material is at least one of coal, natural gas, coke, petroleum coke, and heavy oil. The mass ratio of the added carbon-containing material to the retired lithium-ion battery is ≤50%.

[0017] Preferably, in step S1, the reaction temperature is controlled to be 400°C to 800°C, and the reaction time is ≥30 min; in step S2, the leaching reaction temperature is 20°C to 85°C, and the leaching time is ≥30 min.

[0018] Preferably, in step S3, the solid-liquid separation adopts at least one of a filter press, a centrifuge, a plate and frame filter, a horizontal disc filter, a vertical disc filter, and a vacuum filter.

[0019] Preferably, in step S3, the obtained lithium-containing solution is used for lithium compound production, and the leached residue is used for further extraction of products containing nickel, cobalt and manganese elements.

[0020] The principle is that retired lithium-ion batteries react with chlorine-containing materials under heat. The chlorine-containing materials generate reducing gases (such as hydrocarbons, carbon residue, methane, hydrogen, etc.) during the reaction process, which reduce the high-valent lithium-containing nickel, cobalt, and manganese oxides in the retired lithium-ion batteries, destroy their crystal structure, inhibit the formation of LiF that is poorly soluble in water and / or anhydrous ethanol, and convert the lithium into LiCl that is soluble in water, anhydrous ethanol or a mixture thereof, while converting nickel, cobalt, and manganese into metallic nickel, nickel oxide, cobalt oxide, nickel-manganese oxide, manganese oxide and other substances that are insoluble in water or anhydrous ethanol.

[0021] Therefore, water, anhydrous ethanol or a mixture thereof can be used to selectively extract lithium, and during the reaction process, the Li in the battery is converted into LiCl in the form of LiF, thereby effectively improving the lithium recovery rate.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1) The method of the present invention creatively proposes to use chlorine-containing materials in the thermal reduction process of retired lithium-ion batteries, effectively inhibiting the formation of lithium fluoride that is insoluble in water, promoting the conversion of lithium into lithium chloride that is soluble in water, anhydrous ethanol, or a mixture thereof, thereby effectively improving the subsequent selective leaching rate of lithium and improving the economic benefits of the process; (2) In the method of the present invention, the particularly preferred chlorine-containing material is chlorine-containing organic waste, which is added to the thermal reduction process of the battery to convert the chlorine in the organic matter into lithium chloride, and lithium chloride products can be produced subsequently. Therefore, the present invention also solves the problem of chlorine fixation and the problem of harmless disposal and resource utilization of chlorine-containing organic waste, so the environmental and economic benefits of the process are better; (3) The method of the present invention creatively proposes a method for selectively extracting lithium using anhydrous ethanol. Since the boiling point of anhydrous ethanol is significantly lower than that of water, and the heat capacity is also significantly lower than that of water, the lithium-containing solution can be subsequently recovered by evaporation and crystallization, and the energy consumption for lithium extraction is significantly reduced. DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are intended to explain the present invention but are not intended to limit the present invention.

[0024] The raw materials used in the present invention are purchased from conventional channels or prepared by existing technical methods.

[0025] Example 1: A method for selectively extracting lithium from retired lithium-ion batteries comprises the following steps: (1) Retired lithium-ion batteries (containing cathode materials after physical sorting) and a certain amount of chlorine-containing material (polyvinyl chloride, PVC, 50% chlorine content) are placed in a pyrolysis furnace for reaction. The amount of retired lithium-ion batteries and chlorine-containing material added is 1:1.30 by mass, the reaction temperature is controlled at 550℃-600℃, and the pyrolysis reaction time is 4h.

[0026] (2) Leaching the reaction product of step (1) with deionized water as the leaching agent, the leaching temperature being 30° C., and the leaching time being 120 min.

[0027] (3) The leaching reaction product of step (2) is subjected to solid-liquid separation using a vacuum filter to obtain a lithium-containing solution and leaching residue.

[0028] After testing, the leaching rate of lithium was 98.95%, while the leaching rates of nickel, cobalt and manganese were all 0.01%.

[0029] Example 2: A method for selectively extracting lithium from retired lithium-ion batteries comprises the following steps: (1) Decommissioned lithium-ion batteries (lithium-ion battery cathode materials containing nickel, cobalt, and manganese) are placed in a calciner together with a certain amount of chlorine-containing material (chlorinated rubber, chlorine content 20%), and a certain amount of carbon-containing material (coke) is added to react. The amount of decommissioned lithium-ion batteries, chlorine-containing material, and carbon-containing material added is in a mass ratio of 1:0.3:0.1. The reaction temperature is controlled at 650°C-700°C, and the pyrolysis reaction time is 30 minutes.

[0030] (2) Leaching the reaction product of step (1) with anhydrous ethanol as the leaching agent, the leaching temperature being 20° C., and the leaching time being 150 min.

[0031] (3) The leaching reaction product of step (2) is subjected to solid-liquid separation using a filter press to obtain a lithium-containing solution and leaching residue.

[0032] After testing, the leaching rate of lithium was 99.24%, while the leaching rates of nickel, cobalt and manganese were all 0.01%.

[0033] Example 3: A method for selectively extracting lithium from retired lithium-ion batteries comprises the following steps: (1) Decommissioned lithium-ion batteries (complete lithium nickel cobalt manganese oxide battery packs) and a certain amount of chlorine-containing material (chlorinated resin powder, chlorine content 15%) are placed in a rotary kiln, and a certain amount of carbon-containing material (petroleum coke) is added to react. The amount of decommissioned lithium-ion batteries, chlorine-containing material, and carbon-containing material added is in a mass ratio of 1:0.5:0.3. The reaction temperature is controlled at 600℃-650℃, and the pyrolysis reaction time is 2h.

[0034] (2) Leaching the reaction product of step (1) with anhydrous ethanol as the leaching agent, at a leaching temperature of 60° C., for 100 min.

[0035] (3) The leaching reaction product of step (2) is subjected to solid-liquid separation using a plate-and-frame filter to obtain a lithium-containing solution and leaching residue.

[0036] After testing, the leaching rate of lithium was 97.83%, while the leaching rates of nickel, cobalt and manganese were all 0.01%.

[0037] Comparative Example 1 The difference between this comparative example and Example 1 is that no chlorine-containing material is added, and the other steps are the same as Example 1; after testing, the lithium leaching rate is only 34.62%.

[0038] The results show that this method achieves selective Li recovery and solves the problem of refractory degradation of chlorine-containing organic matter. The method has good recovery efficiency and significant overall economic benefits.

[0039] Comparative Example 2 The difference between this comparative example and Example 3 is that no chlorine-containing material is added, and the other steps are the same as Example 3. After testing, the lithium leaching rate is only 42.30%.

[0040] The results show that this method achieves selective Li recovery and solves the problem of refractory degradation of chlorine-containing organic matter. The method has good recovery efficiency and significant overall economic benefits.

[0041] Comparative Example 3 The difference between this comparative example and Example 4 is that no chlorine-containing material is added, and the other steps are the same as Example 4. The lithium leaching rate was tested to be only 25.74%.

[0042] The results show that this method achieves selective Li recovery and solves the problem of refractory degradation of chlorine-containing organic matter. The method has good recovery efficiency and significant overall economic benefits.

[0043] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. Any technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A method for selectively extracting lithium from retired lithium-ion batteries, characterized in that: The following steps are involved: S1, putting retired lithium-ion batteries and a certain amount of chlorine-containing materials into a reactor to react to obtain a first reaction product, controlling the reaction temperature to 250°C~1000°C, and the reaction temperature ≥15min; S2, leaching the first reaction product obtained in step S1 to obtain a second reaction product, wherein the leaching agent is at least one of water and anhydrous ethanol, the leaching temperature is 15° C. to 100° C., and the leaching time is ≥10 min; S3, performing solid-liquid separation on the second reaction product obtained in step S2 to obtain a lithium-containing solution and leached residue.

2. A method for selectively extracting lithium from retired lithium-ion batteries according to claim 1, characterized in that: The retired lithium-ion batteries are at least one of waste lithium-ion batteries, lithium-ion batteries with shells that have not been disassembled or crushed, materials containing lithium-ion battery positive electrode materials that have been physically sorted, unqualified lithium-ion battery positive electrode powder or pole pieces, a mixture of lithium-ion battery waste and cobalt-containing materials, and a mixture of lithium-ion battery waste and manganese-containing materials.

3. A method for selectively extracting lithium from retired lithium-ion batteries according to claim 2, characterized in that: The retired lithium-ion battery contains one or more of cobalt, nickel, manganese and iron.

4. The method for selectively extracting lithium from retired lithium-ion batteries according to claim 1, characterized in that: The chlorine-containing material is at least one of plastics, rubber, resin, organic solution, organic polymer and organic matter containing chlorine element.

5. A method for selectively extracting lithium from retired lithium-ion batteries according to claim 4, characterized in that: The mass ratio of the added amount of the chlorine-containing material to the retired lithium-ion battery is ≥2%.

6. A method for selectively extracting lithium from retired lithium-ion batteries according to claim 5, characterized in that: The added amount of the chlorine-containing material is 5% to 150% of the mass ratio of the retired lithium-ion battery.

7. A method for selectively extracting lithium from retired lithium-ion batteries according to claim 1, characterized in that: In step S1, the reactor is at least one of a pyrolysis furnace, a rotary kiln, a tunnel kiln, a roasting furnace, and a rotary kiln, and a carbon-containing material is added to the pyrolysis furnace. The carbon-containing material is at least one of coal, natural gas, coke, petroleum coke, and heavy oil. The mass ratio of the added carbon-containing material to the retired lithium-ion battery is ≤50%.

8. The method for selectively extracting lithium from retired lithium-ion batteries according to claim 1, characterized in that: In step S1, the reaction temperature is controlled to be 400°C-800°C, and the reaction time is ≥30min; in step S2, the leaching reaction temperature is 20-85°C, and the leaching time is ≥30min.

9. The method for selectively extracting lithium from retired lithium-ion batteries according to claim 1, characterized in that: In step S3, the solid-liquid separation adopts at least one of a filter press, a centrifuge, a plate and frame filter, a horizontal disc filter, a vertical disc filter, and a vacuum filter.

10. A method for selectively extracting lithium from retired lithium-ion batteries according to claim 1, characterized in that: In step S3, the obtained lithium-containing solution is used for the production of lithium compounds, and the leached residue is used for further extraction of products containing nickel, cobalt and manganese elements.