Method for recovering an organolithium solution and solid lithium-containing product

Abstract

The embodiment of the present application relates to a kind of organic lithium solution recovery method and solid-state lithium-containing product, comprising: the solute of the organic lithium solution to be recycled includes Li-aromatic hydrocarbon complex, solvent includes ether reagent;The organic lithium solution to be recycled also includes lithium hydride;The recovery method includes: for lithium oxidation gas is introduced into the organic lithium solution to be recycled, so that lithium element in the Li-aromatic hydrocarbon complex is oxidized, and the solid-state product generated is deposited on the surface of lithium hydride, and form the solution containing suspended particles;The ether reagent and aromatic hydrocarbon compound in the solution containing suspended particles are evaporated and separated by heating, to obtain the separated solid-state lithium-containing compound, ether reagent and aromatic hydrocarbon compound;The solid-state lithium-containing compound is treated by water or alcohol, to remove lithium hydride in the solid-state lithium-containing compound.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a method for recovering organic lithium solution and solid lithium-containing products. Background Technology

[0002] Lithium-ion battery technology has been widely used in mobile energy storage fields such as electric vehicles, portable tools, and digital products, and will be used in large-scale energy storage and home energy storage in the future. Currently, the electric vehicle market has an increasingly strong demand for high-energy-density, long-life batteries. During operation, a solid electrolyte layer inevitably forms on the surface of the negative electrode, which consumes the active lithium ions inside the battery, resulting in a decrease in the energy density of the lithium-ion battery.

[0003] Pre-lithiation technology is considered an effective way to address the irreversible energy density loss during the first cycle of lithium-ion batteries. Pre-lithiation technology involves pre-adding active lithium ions inside the battery to compensate for this initial loss. Currently proposed pre-lithiation methods include lithium-additive methods, contact pre-lithiation, electrochemical pre-lithiation, and chemical pre-lithiation. Chemical pre-lithiation involves soaking electrode materials or electrode sheets in a chemical pre-lithiation solution. Due to the strong reducing properties of the solution, lithium ions in the solution are inserted into the active material upon contact, thus achieving pre-lithiation of the active material.

[0004] Currently, the widely used pre-lithiation solution is an organolithium solution formulated with ether solvents, aromatic hydrocarbon compounds, and an active lithium source (metallic lithium or lithium-containing active materials). However, organolithium solutions are inherently unstable, and their pre-lithiation ability can significantly decrease or even disappear due to spontaneous failure. Degraded organolithium solutions contain large amounts of ether reagents and aromatic lithium compounds. Furthermore, research has shown that such organolithium solutions can form hazardous chemicals such as lithium hydride during use or storage, posing significant safety hazards. In addition to the hazardous lithium hydride, used organolithium solutions still contain considerable amounts of aromatic lithium complexes, ether solvents, and aromatic hydrocarbon compounds. Direct disposal would pose significant safety problems, waste resources, and cause immense environmental pressure. Summary of the Invention

[0005] The purpose of this invention is to provide a method for recovering organic lithium solutions and solid lithium-containing products, aiming to solve the problems of high risk and significant environmental pressure caused by the direct discharge of organic lithium solutions that have been stored for a long time or have expired.

[0006] Therefore, in a first aspect, embodiments of the present invention provide a method for recovering an organolithium solution, wherein the solute of the organolithium solution to be recovered includes a Li-aromatic hydrocarbon complex, and the solvent includes an ether reagent; the organolithium solution to be recovered also includes lithium hydride; the recovery method includes:

[0007] A gas for lithium oxidation is introduced into the organic lithium solution to be recycled, so that the lithium element in the Li-aromatic hydrocarbon complex is oxidized, and the resulting solid product is deposited on the surface of lithium hydride, forming a solution containing suspended particles.

[0008] The ether reagent and aromatic hydrocarbon compound in the solution containing suspended particles are evaporated and separated by heating to obtain the separated solid lithium-containing compound, ether reagent and aromatic hydrocarbon compound;

[0009] The solid lithium-containing compound is treated with water or alcohol to remove lithium hydride from the solid lithium-containing compound.

[0010] Preferably, the gas used for lithium oxidation includes carbon dioxide;

[0011] The Li-aromatic hydrocarbon complex reacts with carbon dioxide to generate lithium carbonate and aromatic hydrocarbon compounds. The generated lithium carbonate is deposited on the surface of lithium hydride to form the suspended particles.

[0012] More preferably, during the reaction process from the organic lithium solution to be recycled to the solution containing suspended particles, the color of the solution changes from dark to light.

[0013] More preferably, the molar ratio of the total amount of carbon dioxide introduced to the content of active lithium in the organic lithium solution to be recovered is not less than 2:1.

[0014] Preferably, before introducing the gas for lithium oxidation into the organic lithium solution to be recovered, the method further includes: determining the active lithium content in the organic lithium solution to be recovered;

[0015] Specifically, this includes: taking 1 mL of pre-lithiation solution in an inert environment and adding it to a sealed bottle, then injecting sufficient water through a rubber stopper, extracting the gas in the sealed bottle after the reaction and testing it with gas chromatography to determine the amount of H2 generated in the reaction;

[0016] The amount of H2 determined by the test is compared with the standard curve of H2 production / active Li content to obtain the active lithium content in the organic lithium solution to be recovered.

[0017] More preferably, the method further includes: preparing a standard curve of H2 yield / active Li content;

[0018] Specifically, this includes: conducting reactions in closed containers with different ratios of lithium metal and water, determining the yield of H2 generated by the reaction, and plotting a standard curve of H2 yield / active Li content based on the H2 yield and the amount of lithium metal used.

[0019] Preferably, the step of evaporating and separating the ether reagents and aromatic hydrocarbon compounds in the solution containing suspended particles by heating specifically includes:

[0020] The solution containing suspended particles is centrifuged and filtered to obtain the separated solid lithium compound and the separated solution.

[0021] The solution is heated in stages. In the first heating stage, the ether reagent is evaporated and collected, and in the second heating stage, the aromatic hydrocarbon compound is evaporated and collected.

[0022] Preferably, the step of evaporating and separating the ether reagents and aromatic hydrocarbon compounds in the solution containing suspended particles by heating specifically includes:

[0023] The solution containing suspended particles is first heated so that the ether reagent is evaporated and collected;

[0024] The remaining solid material is heated a second time to sublimate and separate the aromatic hydrocarbon compounds from the remaining solid material and collect them, thus obtaining a solid lithium-containing compound.

[0025] Preferably, the chemical reaction of treating the solid lithium-containing compound with water includes: LiH + H2O = LiOH + H2↑;

[0026] The chemical reactions involving the treatment of the solid lithium-containing compound with alcohol include: LiH + CH3CH2OH = CH3CH2OLi + H2↑; CH3CH2OLi + H2O → LiOH + CH4↑.

[0027] Secondly, embodiments of the present invention provide a solid lithium-containing product, which is obtained by the organic lithium solution recovery method described in the first aspect above.

[0028] The organic lithium solution recovery method provided in this invention consumes active lithium in the solution through the reaction between gas and organic lithium solution, and then recovers it by heating to separate ether reagents and aromatic hydrocarbon compounds, thereby giving it high reuse value. Finally, the byproduct lithium hydride generated during the oxidation failure process is treated with water or alcohol, which can reduce the danger of the failed pre-lithiation solution. Attached Figure Description

[0029] Figure 1 A flowchart of an organolithium solution recovery method is provided for embodiments of the present invention;

[0030] Figure 2 The active lithium content-hydrogen peak area curve obtained by gas chromatography (GC) test;

[0031] Figure 3The infrared spectra of the recovered aromatic hydrocarbon compound biphenyl from Example 1 of this invention are compared with those of the original biphenyl.

[0032] Figure 4 The infrared spectra of the recovered ether organic solvent 2-methyltetrahydrofuran in Example 1 of this invention are compared with those of the original 2-methyltetrahydrofuran.

[0033] Figure 5 The image shows the XRD pattern of lithium carbonate recovered in Example 1 of this invention. Detailed Implementation

[0034] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0035] This invention provides a method for recovering organic lithium solutions, which can be used to recover failed or long-term stored chemical pre-lithiation solutions, and can also be used for further recovery of organic lithium solutions obtained by organic cleaning of the negative electrode of a recycled battery. It can reduce the danger of failed organic lithium solutions and recover various chemical substances in the organic lithium solutions, including ether solvents, aromatic hydrocarbon compounds and lithium elements, wherein the lithium elements are converted into lithium-containing compounds, such as lithium carbonate.

[0036] The solute in the organolithium solution to be recovered using the method of the present invention includes Li-aromatic hydrocarbon complexes, and the solvent includes ether reagents; the organolithium solution to be recovered also includes lithium hydride; lithium hydride is formed during the use or storage of organolithium solutions prepared by ether solvents and aromatic hydrocarbon lithium complexes.

[0037] The main steps are as follows Figure 1 As shown, it includes:

[0038] Step 110: A gas for lithium oxidation is introduced into the organic lithium solution to be recycled, so that the lithium element in the Li-aromatic hydrocarbon complex is oxidized and the resulting solid product is deposited on the surface of lithium hydride to form a solution containing suspended particles.

[0039] Specifically, the gases used for lithium oxidation include carbon dioxide, and may also be mixed with inert gases such as nitrogen or argon.

[0040] Li-aromatic hydrocarbon complexes react with carbon dioxide to form lithium carbonate and aromatic hydrocarbon compounds. The resulting lithium carbonate deposits on the surface of lithium hydride, forming suspended particles. Because the surface energy of LiH in solution is relatively high, it acts as a nucleating particle, reducing the nucleation energy. Therefore, the generated Li2CO3 is deposited on the LiH surface, forming a LiH surface-encapsulated Li2CO3 structure.

[0041] The molar ratio of the total amount of carbon dioxide introduced to the active lithium content in the organic lithium solution to be recovered should not be less than 2:1. The aeration time is related to the concentration or content of organic lithium, and is specifically controlled as 10X (min)-120X (min) (X is the concentration of active lithium in the solution, in mol / L). In practice, to ensure sufficient reaction, it is preferred to be no less than 30 min.

[0042] During the reaction of the organic lithium solution to be recovered into a solution containing suspended particles, the solution color changes from dark to light. The initial color of the solution is determined by the Li-aromatic hydrocarbon complex; different aromatic hydrocarbon radicals and their complexes with Li produce different colors. After the reaction, the Li-aromatic hydrocarbon complex reacts with carbon dioxide to form lithium carbonate and aromatic hydrocarbon compounds. The lithium carbonate exists as white suspended particles in the colorless solution.

[0043] The total amount of carbon dioxide introduced can be determined by measuring the active lithium content in the organic lithium solution to be recovered.

[0044] The method for determining the active lithium content in the organic lithium solution to be recovered specifically includes: taking 1 mL of pre-lithiation solution in an inert environment and adding it to a sealed bottle, then injecting sufficient water through a rubber stopper, extracting the gas in the sealed bottle after the reaction and testing it with gas chromatography to determine the amount of H2 generated in the reaction; comparing the determined amount of H2 with the H2 production / active Li content standard curve to obtain the active lithium content in the organic lithium solution to be recovered.

[0045] The H2 yield / active Li content standard curve can be prepared in advance experimentally. For example... Figure 2 The reaction was carried out in a closed container with different ratios of lithium metal and water to determine the yield of H2 produced. Based on the H2 yield and the amount of lithium metal used, a standard curve of H2 yield / active Li content can be plotted.

[0046] Step 120: Evaporate and separate the ether reagent and aromatic hydrocarbon compound in the solution containing suspended particles by heating to obtain the separated solid lithium-containing compound, ether reagent and aromatic hydrocarbon compound;

[0047] Separation can be implemented in different ways:

[0048] For example, the solution containing suspended particles can be centrifuged and filtered to obtain the separated solid lithium-containing compound and the separated solution; then the solution is heated in stages. In the first heating stage, the ether reagent is evaporated and collected, and in the second heating stage, the aromatic hydrocarbon compound is evaporated and collected.

[0049] For example, the solution containing suspended particles can be heated first to evaporate and collect the ether reagent; then the remaining solid material can be heated second to sublimate and separate the aromatic hydrocarbon compound from the remaining solid material and collect it, thus obtaining a solid lithium-containing compound.

[0050] Ether reagents generally have relatively low evaporation temperatures, such as ethyl ether at 34.6°C, ethylene oxide at 10.7°C, 2-methyltetrahydrofuran at 79.9°C, and tetrahydrofuran at 66°C. Aromatic hydrocarbons, on the other hand, have higher evaporation temperatures, such as toluene at 110.6°C, xylene (with three isomers: o-xylene, m-xylene, and p-xylene) at 138-144°C, ethylbenzene at 136°C, naphthalene at 218°C, and biphenyl at 255°C. Therefore, different evaporation temperature settings can be used to achieve the separation and recovery of ether reagents and aromatic hydrocarbons. The specific temperature setting can be determined based on the specific types of ether reagents and aromatic hydrocarbons to be recovered.

[0051] Step 130: Treat the solid lithium compound with water or alcohol to remove lithium hydride from the solid lithium compound.

[0052] Specifically, water or alcohol reacts with lithium hydride through lithium carbonate deposited on its surface. Because lithium carbonate is deposited, it is not dense, allowing liquid immersion to easily contact and react with the lithium hydride.

[0053] The chemical reactions involved in water treatment of solid lithium compounds include: LiH + H₂O = LiOH + H₂↑;

[0054] The chemical reactions involving the treatment of solid lithium compounds with alcohol include: LiH + CH3CH2OH = CH3CH2OLi + H2↑; CH3CH2OLi + H2O → LiOH + CH4↑.

[0055] After filtration and washing, solid lithium-containing product Li2CO3 was finally obtained.

[0056] The above method consumes active lithium in the solution through the reaction between gas and organic lithium solution. Then, the ether reagent and aromatic hydrocarbon compound are separated by heating for recovery, thus giving it high reuse value. Finally, the lithium hydride byproduct generated during the oxidation failure process is treated with water or alcohol, which can reduce the danger of the failed pre-lithiation solution.

[0057] To more clearly illustrate the purpose and advantages of the present invention, the following description, in conjunction with embodiments, further elaborates on the invention. Furthermore, the embodiments described herein are only some examples; all other embodiments obtained by those skilled in the art based on the embodiments described herein without inventive effort are within the scope of protection of the present invention. Additionally, it should be understood that these embodiments are merely for more detailed explanation and should not be construed as limiting the invention in any way, i.e., they are not intended to limit the scope of protection of the present invention.

[0058] Example 1

[0059] (1) Take 1L of 1mol / L organic lithium solution (a solution containing lithium biphenyl and 2-methyltetrahydrofuran) and place it in a 2.5L gas washing bottle. Slowly introduce high-purity carbon dioxide gas into it and keep the gas flowing until the liquid turns from dark green to transparent. Continue to introduce the gas for half an hour to ensure that the reaction is complete.

[0060] (2) Add the treated solution to a centrifuge tube and centrifuge at 8000 revolutions per minute. After centrifugation, collect the supernatant and the bottom sediment.

[0061] (3) The ether reagent 2-methyltetrahydrofuran in the supernatant was recovered by heating and condensation at a temperature of 150 degrees Celsius. After solvent recovery, the temperature was raised to 350 degrees Celsius to recover biphenyl.

[0062] (4) Disperse the collected bottom sediment solid in alcohol, use alcohol to treat the lithium hydride in the solid, and at the same time dissolve any remaining aromatic hydrocarbon compounds. After filtration, obtain a white solid. Place the white solid in a 70-degree forced-air oven to dry for 24 hours and collect it in a reagent bottle to obtain the recovered lithium carbonate.

[0063] The 2-methyltetrahydrofuran, biphenyl, and lithium carbonate obtained in this example were tested.

[0064] Figure 3 The infrared spectra of the recovered aromatic hydrocarbon compound biphenyl were compared with those of the original biphenyl. The peak positions and intensities of the spectra were completely consistent, indicating that the recovered product was very pure.

[0065] Figure 4 The infrared spectra of the recovered ether organic solvent 2-methyltetrahydrofuran and the original 2-methyltetrahydrofuran show that the peak positions and intensities are completely consistent, indicating that the recovered product is pure and free of impurities.

[0066] Figure 5 The X-ray diffraction (XRD) spectrum of the recovered lithium carbonate was compared with the information in the PDF card library. The peak positions and relative intensities were consistent, indicating that the product was pure and had good crystallinity.

[0067] Example 2

[0068] (1) Take 1L of 1mol / L organic lithium solution (a solution containing lithium naphthalene and tetrahydrofuran) and place it in a 2.5L gas washing bottle. Slowly introduce a mixture of carbon dioxide and argon gas (carbon dioxide volume content is 20%) into the bottle. Continue to introduce the gas until the liquid changes from dark blue to transparent. Continue to introduce the gas for half an hour to ensure that the reaction is complete.

[0069] (2) Add the treated solution to the vacuum filtration device, filter the solution using a 0.22-micron microporous membrane, and after rinsing several times, obtain the filtrate and grayish-white filter residue.

[0070] (3) The ether reagent tetrahydrofuran in the filtrate was recovered by heating and condensation at a temperature of 120 degrees Celsius. After solvent recovery, naphthalene was recovered by heating at 240 degrees Celsius.

[0071] (4) Disperse the collected filter residue in water, treat the lithium hydride in the solid with water, then filter to obtain a white solid, place the solid in a vacuum oven at 120 degrees and dry it for 12 hours, then collect it in a reagent bottle to obtain the recovered lithium carbonate.

[0072] Example 3

[0073] (1) Take 1L of 1mol / L organic lithium solution (containing lithium biphenyl and 2-methyltetrahydrofuran) and place it in a 2.5L gas washing bottle. Slowly introduce high-purity carbon dioxide gas into it and keep the gas flowing until the liquid turns from dark green to transparent. Continue to introduce the gas for half an hour to ensure that the reaction is complete.

[0074] (2) Add the treated solution into a filter press container and perform solid-liquid separation of the treated liquid under a pressure of 1 MPa, and collect the filtrate and filter residue.

[0075] (3) The ether reagent 2-methyltetrahydrofuran in the filtrate was recovered by heating and condensation at a temperature of 180 degrees. After solvent recovery, the temperature was further increased to 280 degrees to recover biphenyl.

[0076] (4) Disperse the collected filter residue in alcohol, use alcohol to treat the lithium hydride in the solid, and at the same time dissolve any remaining aromatic hydrocarbon compounds. Filter to obtain a white solid, place the solid in a 70-degree forced-air oven to dry for 24 hours, and collect it in a reagent bottle to obtain the recovered lithium carbonate.

[0077] Example 4

[0078] (1) Take 1L of 1mol / L organic lithium solution (a solution containing lithium naphthalene and ethylene glycol dimethyl ether) and place it in a 2.5L gas washing bottle. Slowly introduce a mixture of nitrogen and carbon dioxide (carbon dioxide volume content is 50%) into it. Continue to introduce the gas until the liquid changes from dark blue to milky white. Continue to introduce the gas for half an hour to ensure that the reaction is complete.

[0079] (2) The treated solution was placed into a centrifuge tube and centrifuged at 8000 revolutions per minute to obtain the supernatant and milky white precipitate.

[0080] (3) Ethylene glycol dimethyl ether, an ether reagent, was recovered from the supernatant by heating and condensation at a temperature of 100 degrees Celsius. After solvent recovery, naphthalene was recovered by heating at 250 degrees Celsius.

[0081] (4) Disperse the collected filter residue in alcohol and use alcohol to remove organic impurities from the filter residue. Then filter to obtain a white solid. Place the solid in a vacuum oven at 120 degrees Celsius and vacuum dry for 12 hours. Then collect it in a reagent bottle to obtain the recovered lithium carbonate.

[0082] Example 5

[0083] (1) Take 1L of 0.5mol / L organic lithium solution (containing 4-methylbiphenyl lithium and 2-methyltetrahydrofuran), slowly introduce the solution into a box containing a mixture of carbon dioxide and argon (carbon dioxide volume content is 50%), keep the gas flowing into the box to ensure a sufficient gas supply, and after the liquid turns from dark green to transparent, remove the liquid from the box.

[0084] (2) The exported solution is transported to a filter press and solid-liquid separation is performed at a pressure of 0.5 MPa to collect the filtrate and filter residue;

[0085] (3) The ether reagents in the filtrate were recovered by heating and condensation at a temperature of 150 degrees Celsius. After the solvent was recovered, the 4-methylbiphenyl was recovered by heating at 250 degrees Celsius.

[0086] (4) Disperse the collected bottom sediment solid in alcohol, use alcohol to treat the lithium hydride in the solid, and at the same time dissolve any remaining aromatic hydrocarbon compounds. Filter to obtain a white solid, place the solid in a 70-degree forced-air oven to dry for 24 hours, and collect it in a reagent bottle to obtain the recovered lithium carbonate.

[0087] Example 6

[0088] (1) Take 1L of 0.5mol / L organic lithium solution (containing 2-fluorobiphenyl lithium and 2-methyltetrahydrofuran), slowly introduce the solution into a box containing a mixture of carbon dioxide and argon (volume ratio 1:1), keep the gas flowing into the box to ensure a sufficient gas supply, and after the liquid turns from dark green to transparent, remove the liquid from the box.

[0089] (2) The exported solution is transported to a storage tank, and after the solid products in it settle naturally, the supernatant and the bottom precipitate are separated.

[0090] (3) Aromatic hydrocarbons in the supernatant are recovered by spray drying, and ether reagents are recovered by heating (at 150 degrees) at the exhaust end.

[0091] (4) Add water to the bottom precipitate, and after the layers are separated, take the supernatant and repeat the process of step (3). The remaining precipitate is dried by blast drying at 70 degrees Celsius. The powder after treatment is washed with alcohol, dried and collected to obtain the recovered lithium carbonate.

[0092] This invention removes hazardous chemicals, such as aromatic lithium compounds and lithium hydride byproducts, from expired or recyclable chemical pre-lithiation solutions and organic lithium solutions generated during negative electrode cleaning. This reduces the risk of pollution from emissions and saves on expensive wastewater treatment costs. Implementation verification shows that this invention can recover over 70% of ether solvents and aromatic compounds from pre-lithiation solutions. Furthermore, this invention can convert most of the recovered lithium from organic lithium solutions into high-value-added lithium compounds, such as lithium carbonate, giving them high reuse value.

[0093] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for recovering organic lithium solution, characterized in that, The solute in the organolithium solution to be recovered includes Li-aromatic hydrocarbon complexes, and the solvent includes ether reagents; the organolithium solution to be recovered also includes lithium hydride; the recovery method includes: A gas for lithium oxidation, including carbon dioxide, is introduced into the organic lithium solution to be recovered. The Li-aromatic hydrocarbon complex reacts with carbon dioxide to generate lithium carbonate and aromatic hydrocarbon compounds. The generated lithium carbonate is deposited on the surface of lithium hydride to form suspended particles, resulting in a solution containing suspended particles. The molar ratio of the total amount of carbon dioxide introduced to the content of active lithium in the organic lithium solution to be recovered is not less than 2:

1. The ether reagent and aromatic hydrocarbon compound in the solution containing suspended particles are evaporated and separated by heating to obtain the separated solid lithium-containing compound, ether reagent and aromatic hydrocarbon compound; The solid lithium-containing compound is treated with water or alcohol to remove lithium hydride, thereby obtaining the solid lithium-containing product lithium carbonate.

2. The recycling method according to claim 1, characterized in that, During the reaction process from the organic lithium solution to the solution containing suspended particles, the color of the solution changes from dark to light.

3. The recycling method according to claim 1, characterized in that, Before introducing the gas for lithium oxidation into the organic lithium solution to be recovered, the method further includes: determining the active lithium content in the organic lithium solution to be recovered; Specifically, this includes: taking 1 mL of pre-lithiation solution in an inert environment and adding it to a sealed bottle, then injecting sufficient water through a rubber stopper, extracting the gas in the sealed bottle after the reaction and testing it with gas chromatography to determine the amount of H2 generated in the reaction; The amount of H2 determined by the test is compared with the standard curve of H2 production / active Li content to obtain the active lithium content in the organic lithium solution to be recovered.

4. The recycling method according to claim 3, characterized in that, The method further includes: preparing a standard curve of H2 yield / active Li content; Specifically, this includes: conducting reactions in closed containers with different ratios of lithium metal and water, determining the yield of H2 generated by the reaction, and plotting a standard curve of H2 yield / active Li content based on the H2 yield and the amount of lithium metal used.

5. The recycling method according to claim 1, characterized in that, The process of evaporating and separating the ether reagents and aromatic hydrocarbon compounds from the solution containing suspended particles by heating specifically includes: The solution containing suspended particles is centrifuged and filtered to obtain the separated solid lithium compound and the separated solution. The solution is heated in stages. In the first heating stage, the ether reagent is evaporated and collected, and in the second heating stage, the aromatic hydrocarbon compound is evaporated and collected.

6. The recycling method according to claim 1, characterized in that, The process of evaporating and separating the ether reagents and aromatic hydrocarbon compounds from the solution containing suspended particles by heating specifically includes: The solution containing suspended particles is first heated so that the ether reagent is evaporated and collected; The remaining solid material is heated a second time to sublimate and separate the aromatic hydrocarbon compounds from the remaining solid material and collect them, thus obtaining a solid lithium-containing compound.

7. The recycling method according to claim 1, characterized in that, The chemical reaction of treating the solid lithium-containing compound with water includes: LiH + H2O = LiOH + H2↑; The chemical reactions involving the treatment of the solid lithium-containing compound with alcohol include: LiH + CH3CH2OH = CH3CH2OLi + H2↑; CH3CH2OLi + H2O → LiOH + CH4↑.

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