Method for recycling lithium lanthanum zirconium oxide type solid electrolyte waste

Abstract

The present application belongs to the technical field of resource recycling, and provides a recycling method of lithium lanthanum zirconium oxide type solid electrolyte waste, which comprises the following steps: mixing lithium lanthanum zirconium oxide type solid electrolyte waste, water and carbon dioxide, and then performing carbonization reaction to obtain lithium-containing liquid and lanthanum zirconium oxide residue; performing washing and drying on the lanthanum zirconium oxide residue; mixing the lithium-containing liquid and inorganic alkali to obtain lithium-containing purified liquid and alkali purification residue; performing pyrolysis on the lithium-containing purified liquid to obtain lithium carbonate, and completing the recycling. Through carbonization to extract lithium, the lithium leaching rate reaches more than 99%, and then the impurity removal and lithium precipitation are performed to obtain lithium carbonate, which meets the requirement of battery-grade lithium carbonate; and lanthanum and zirconium exist in the form of oxides in the residue, which can be used as raw materials for synthesizing lithium lanthanum zirconium oxide type solid electrolyte after washing and drying. The present application avoids the traditional acid leaching and roasting processes, has the advantages of simple operation, low energy consumption, green environmental protection, high recovery rate and the like, is suitable for industrialized large-scale production, and has good social value and economic benefits.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of resource recycling, and in particular to a recycling method for lithium lanthanum zirconium oxide type solid electrolyte waste. BACKGROUND

[0002] With the popularization and application of new energy vehicles, lithium ion batteries as an effective electric energy storage chemical device have higher requirements for their safety performance and energy density. Compared with other secondary battery systems (such as lead-acid batteries), lithium ion batteries have many advantages such as high energy density, long cycle life, no memory effect and the like. The emergence of solid-state lithium ion batteries further enables lithium ion batteries to achieve the unification of high energy density and high safety, and is generally believed to be the inevitable development trend of future energy storage batteries. As a core material of the full solid-state lithium metal battery, the garnet solid-state electrolyte (represented by lithium lanthanum zirconium oxide solid electrolyte Li7La3Zr2O 12 (LLZO) has high lithium ion conductivity, wide electrochemical window and good stability to lithium, and has been widely studied in the field of inorganic solid-state electrolytes and composite polymer electrolytes. These studies are mainly about the exploration of the preparation of lithium lanthanum zirconium oxide type solid electrolyte, and methods are provided to synthesize high-performance solid electrolyte to promote the performance improvement of lithium ion batteries. However, the current research on lithium lanthanum zirconium oxide type solid electrolyte mainly focuses on its preparation synthesis, interface modification, composite new material development and the like, and there is little research and development on the recycling and resource technology of valuable metals in LLZO type solid electrolyte. The research on solid electrolyte recycling and metal material extraction and reuse not only contributes to resource conservation, waste valuable metal high-value recycling and environmental protection, but also provides a new expansion for the current research on LLZO type solid electrolyte.

[0003] The patent CN113422122A can extract Li + embedded in the anode electrode through an external electric field, and recovers Li in the form of LiOH, and collects H2. This method mainly recovers lithium elements in the LLZTO solid electrolyte, and does not consider the recovery of lanthanum and zirconium elements; when the electrolysis method is used for recycling, the recovery cost is high, which is not conducive to batch processing; and hydrogen gas is generated, which has safety risks.

[0004] Invention patent CN115584397A describes a method for disassembling a semi-solid-state battery. The resulting materials are divided into positive electrode material, negative electrode material, and a solid separator. The solid separator is sheared and crushed, then immersed in NMP. The filter residue mainly consists of lithium, lanthanum, zirconium, titanium, and oxygen. After calcination, the filter residue is leached with sulfuric acid. Filtration yields lithium sulfate and lanthanum sulfate filtrate, as well as filter residue containing zirconium dioxide and titanium dioxide. The filter residue is washed and dried, and then used directly as a solid electrolyte raw material. Ammonia is added to the lithium sulfate and lanthanum sulfate filtrate to obtain lanthanum hydroxide precipitate, which is then filtered and washed to obtain the lanthanum hydroxide product. This method has a long process flow, consumes a large amount of acid and alkali, and the acid leaching process also generates toxic and harmful gases.

[0005] Invention patent CN117105262A describes a process involving soaking, ultrasonically cleaning, and drying a lithium-lanthanum-zirconium-oxygen solid electrolyte, followed by ball milling to obtain solid electrolyte powder. This powder is then calcined with NMP. The calcined solid electrolyte waste is dissolved, stirred, and filtered to obtain zirconium-containing filter residue and a filtrate containing lanthanum and lithium. The zirconium-containing filter residue is then washed, dried, ball-milled, and chlorinated to obtain zirconium chloride. The lanthanum and lithium-containing filtrate is adjusted to alkaline pH and filtered to obtain a lithium-containing filtrate and lanthanum hydroxide precipitate. The precipitate is washed, dried, and calcined to obtain lanthanum oxide. Sodium carbonate is added to the lithium-containing filtrate, and the mixture is filtered and dried to obtain lithium carbonate. This method also involves calcination and acid leaching, resulting in a long process flow, high acid and alkali consumption, and high production costs. Summary of the Invention

[0006] The purpose of this invention is to overcome the deficiencies in the prior art and provide a method for recycling lithium lanthanum zirconium oxide type solid electrolyte waste.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for recycling lithium lanthanum zirconium oxide type solid electrolyte waste, comprising the following steps:

[0009] (1) Lithium lanthanum zirconium oxide solid electrolyte waste, water and carbon dioxide are mixed and then carbonized to obtain lithium-containing liquid and lanthanum zirconium oxide slag.

[0010] (2) The lanthanum zirconium oxide slag is washed and dried;

[0011] (3) Mix lithium-containing liquid and inorganic alkali to obtain lithium-containing purification liquid and alkalized impurity removal residue;

[0012] (4) The lithium-containing purification liquid is pyrolyzed to obtain lithium carbonate, thus completing the recovery.

[0013] Preferably, the particle size of the lithium lanthanum zirconium oxide type solid electrolyte waste in step (1) is 100-200 mesh.

[0014] Preferably, in step (1), the mass ratio of lithium lanthanum zirconium oxide solid electrolyte waste to water is 1:3 to 6.

[0015] Preferably, the carbonization reaction in step (1) is carried out at a pressure of 0.3 to 1.5 MPa for 3 to 10 hours.

[0016] Preferably, in step (2), the washing is done with water until the pH of the washing solution is neutral.

[0017] Preferably, the inorganic base in step (3) is one or more of sodium hydroxide, potassium hydroxide and lithium hydroxide.

[0018] Preferably, the pH after mixing in step (3) is 12-13, and the mixing time is 30-60 min.

[0019] Preferably, the pyrolysis temperature in step (4) is 85–100°C and the time is 1–4 h.

[0020] This invention provides a method for recycling lithium lanthanum zirconium oxide solid electrolyte waste, comprising the following steps: mixing the lithium lanthanum zirconium oxide solid electrolyte waste, water, and carbon dioxide, and then performing a carbonization reaction to obtain a lithium-containing liquid and lanthanum zirconium oxide slag; washing and drying the lanthanum zirconium oxide slag; mixing the lithium-containing liquid with an inorganic alkali to obtain a lithium-containing purified liquid and an alkalized impurity-removing slag; and pyrolyzing the lithium-containing purified liquid to obtain lithium carbonate, thus completing the recycling. This invention directly extracts lithium through carbonization, achieving a lithium leaching rate of over 99%. After impurity removal and lithium precipitation, lithium carbonate is obtained, and its product quality meets the requirements of battery-grade lithium carbonate (YS / T 582-2013). Lanthanum and zirconium are almost not leached, existing as oxides in the slag, which, after washing and drying, can be used as raw materials for synthesizing lithium lanthanum zirconium oxide solid electrolytes. This invention avoids traditional acid leaching and roasting processes, and has advantages such as simple operation, low energy consumption, environmental friendliness, and high recovery rate. It is suitable for large-scale industrial production and has significant social value and considerable economic benefits. Attached Figure Description

[0021] Figure 1 This is a schematic flowchart of the method for recycling lithium lanthanum zirconium oxide type solid electrolyte waste according to the present invention. Detailed Implementation

[0022] This invention provides a method for recycling lithium lanthanum zirconium oxide type solid electrolyte waste, comprising the following steps:

[0023] (1) Lithium lanthanum zirconium oxide solid electrolyte waste, water and carbon dioxide are mixed and then carbonized to obtain lithium-containing liquid and lanthanum zirconium oxide slag.

[0024] (2) The lanthanum zirconium oxide slag is washed and dried;

[0025] (3) Mix lithium-containing liquid and inorganic alkali to obtain lithium-containing purification liquid and alkalized impurity removal residue;

[0026] (4) The lithium-containing purification liquid is pyrolyzed to obtain lithium carbonate, thus completing the recovery.

[0027] In this invention, the lithium lanthanum zirconium oxide type solid electrolyte waste comes from the lithium lanthanum zirconium oxide type solid electrolyte waste generated during the dismantling of scrapped solid or semi-solid lithium-ion batteries or from the unqualified products generated during the preparation of lithium lanthanum zirconium oxide type solid electrolyte; the lithium lanthanum zirconium oxide type solid electrolyte waste is crushed and ball-milled, and the particle size of the lithium lanthanum zirconium oxide type solid electrolyte waste in step (1) is preferably 100-200 mesh, more preferably 120-180 mesh, and more preferably 140-160 mesh.

[0028] In this invention, the mass ratio of lithium lanthanum zirconium oxide type solid electrolyte waste to water in step (1) is preferably 1:3 to 6, more preferably 1:4 to 5, and even more preferably 1:4.2 to 4.8.

[0029] In this invention, carbon dioxide is introduced to maintain the pressure of the carbonization reaction. The pressure of the carbonization reaction in step (1) is preferably 0.3 to 1.5 MPa, more preferably 0.5 to 1 MPa, and even more preferably 0.6 to 0.8 MPa; the time is preferably 3 to 10 h, more preferably 4 to 8 h, and even more preferably 5 to 6 h.

[0030] In this invention, the reaction principle of step (1) is as follows: lithium lanthanum zirconium oxide solid electrolyte undergoes lithium-hydrogen replacement with water, and CO2 is introduced to react under a certain pressure to generate lithium bicarbonate; the equation is as follows:

[0031] 2Li7La3Zr2O 12 +7H₂O + 14CO₂ == La₆Zr₄O 17 +14LiHCO3

[0032] In this invention, in step (2), the lanthanum zirconium oxide slag is washed with water until the pH of the washing solution is neutral, and then dried, which can be directly used as a raw material for synthesizing lithium lanthanum zirconium oxide solid electrolyte.

[0033] In this invention, the inorganic base mentioned in step (3) is one or more of sodium hydroxide, potassium hydroxide and lithium hydroxide.

[0034] In this invention, the pH after mixing in step (3) is preferably 12-13, more preferably 12.2-12.8, and even more preferably 12.4-12.6; the mixing time is preferably 30-60 min, more preferably 35-55 min, and even more preferably 40-50 min.

[0035] In this invention, after the mixing in step (3) is completed, the lithium-containing purified liquid and the alkalized impurity-removing residue are obtained by pressure filtration.

[0036] In this invention, the pyrolysis temperature in step (4) is preferably 85-100°C, more preferably 90-95°C, and even more preferably 92-93°C; the time is preferably 1-4 hours, more preferably 1.5-3.5 hours, and even more preferably 2-3 hours.

[0037] In this invention, after the pyrolysis of step (4) is completed, the system is centrifuged, washed and dried to obtain lithium carbonate.

[0038] A schematic flowchart of the method for recovering lithium lanthanum zirconium oxide type solid electrolyte waste of the present invention is shown below. Figure 1 As shown.

[0039] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0040] Example 1

[0041] The lithium-lanthanum-zirconium-oxygen solid electrolyte was pulverized and ground through a ball mill and passed through a 150-mesh sieve. 1 kg of lithium-lanthanum-zirconium-oxygen solid electrolyte powder (Li: 3.7%, La: 30.8%, Zr: 10.3%) was weighed and mixed with 4.5 L of pure water to form a slurry. CO2 was introduced, and the pressure was maintained at 0.55 MPa for 6 hours. After pressure filtration, a lithium-containing liquid and lanthanum-zirconium oxide slag were obtained. The lanthanum-zirconium oxide slag was washed with water until the pH of the washing liquid was neutral, and then dried. This slag can be directly used as a raw material for synthesizing the lithium-lanthanum-zirconium-oxygen solid electrolyte. Sodium hydroxide was added to the lithium-containing liquid to adjust the pH to 12.1, and the reaction was carried out at room temperature for 30 minutes. After pressure filtration, a lithium-containing purified liquid and an alkali-treated impurity-removed slag were obtained. The lithium-containing purified liquid was heated to 95℃ and reacted for 2 hours. After the reaction was complete, it was centrifuged, washed, and dried to obtain 166 g of lithium carbonate.

[0042] Example 2

[0043] The lithium-lanthanum-zirconium-oxygen solid electrolyte was pulverized and ground through a ball mill and passed through a 150-mesh sieve. 1 kg of lithium-lanthanum-zirconium-oxygen solid electrolyte powder (Li: 4.0%, La: 33.5%, Zr: 13.7%) was weighed and mixed with 4.7 L of pure water to form a slurry. CO2 was introduced, and the pressure was maintained at 0.6 MPa for 5 h. After pressure filtration, a lithium-containing solution and lanthanum-zirconium oxide slag were obtained. The lanthanum-zirconium oxide slag was washed with water until the pH of the washing solution was neutral, and then dried. This slag can be directly used as a raw material for synthesizing the lithium-lanthanum-zirconium-oxygen solid electrolyte. Potassium hydroxide was added to the lithium-containing solution to adjust the pH to 12.0, and the reaction was carried out at room temperature for 30 min. After pressure filtration, a lithium-containing purified solution and an alkali-treated impurity-removed slag were obtained. The lithium-containing purified solution was heated to 95℃ and reacted for 2 h. After the reaction was complete, the solution was centrifuged, washed, and dried to obtain 179 g of lithium carbonate.

[0044] Example 3

[0045] The lithium-lanthanum-zirconium-oxygen solid electrolyte was pulverized and ground through a ball mill and passed through a 150-mesh sieve. 1 kg of lithium-lanthanum-zirconium-oxygen solid electrolyte powder (Li: 3.5%, La: 30.4%, Zr: 11.7%) was weighed and mixed with 4.3 L of pure water to form a slurry. CO2 was introduced, and the pressure was maintained at 0.55 MPa for 6 hours. After pressure filtration, a lithium-containing solution and lanthanum-zirconium oxide slag were obtained. The lanthanum-zirconium oxide slag was washed with water until the pH of the washing solution was neutral, and then dried. This slag can be directly used as a raw material for synthesizing the lithium-lanthanum-zirconium-oxygen solid electrolyte. Lithium hydroxide was added to the lithium-containing solution to adjust the pH to 12.1, and the reaction was carried out at room temperature for 30 minutes. After pressure filtration, a lithium-containing purified solution and an alkali-treated impurity-removed slag were obtained. The lithium-containing purified solution was heated to 100℃ and reacted for 2 hours. After the reaction was complete, the solution was centrifuged, washed, and dried to obtain 160 g of lithium carbonate.

[0046] The chemical composition of the lanthanum oxide zirconium slag and lithium carbonate obtained in Examples 1-3 was analyzed. The chemical composition of the lanthanum oxide zirconium slag is shown in Table 1.

[0047] Table 1 Chemical composition of lanthanum oxide zirconium slag

[0048] Li (wt%) La (wt%) Zr (wt%) Al (wt%) Fe (wt%) Example 1 0.031 32.0 10.7 0.561 0.810 Example 2 0.039 34.9 14.8 0.667 0.552 Example 3 0.032 31.5 12.1 0.674 0.715

[0049] The chemical composition of lithium carbonate obtained in Examples 1-3 is shown in Table 2.

[0050] Table 2 Chemical Composition of Lithium Carbonate

[0051]

[0052] As can be seen from Table 2, the quality of lithium carbonate meets the requirements of the YS / T 582-2013 battery-grade lithium carbonate standard.

[0053] As can be seen from the above embodiments, the present invention directly extracts lithium through carbonization, with a lithium leaching rate of over 99%. After removing impurities and precipitating lithium, lithium carbonate is obtained, and the product quality meets the requirements of battery-grade lithium carbonate (YS / T 582-2013). Lanthanum and zirconium are almost not leached and exist in the residue in the form of oxides. After washing and drying, they can be used as raw materials for synthesizing lithium lanthanum zirconium oxide solid electrolyte.

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for recycling lithium lanthanum zirconium oxide type solid electrolyte waste, characterized in that, Includes the following steps: 1) Lithium lanthanum zirconium oxide solid electrolyte waste, water and carbon dioxide are mixed and then subjected to carbonization reaction to obtain lithium-containing liquid and lanthanum zirconium oxide slag; 2) The lanthanum oxide zirconium slag is washed and dried; 3) The lithium-containing liquid and inorganic alkali are mixed to obtain a lithium-containing purification liquid and an alkalized residue for impurity removal; 4) The lithium-containing purification solution is pyrolyzed to obtain lithium carbonate, thus completing the recovery process; In step 1), the mass ratio of lithium lanthanum zirconium oxide solid electrolyte waste to water is 1:3~6; In step 2), the washing process involves rinsing with water until the pH of the washing solution is neutral. In step 3), the pH after mixing is 12-13, and the mixing time is 30-60 minutes.

2. The method for recycling lithium lanthanum zirconium oxide type solid electrolyte waste as described in claim 1, characterized in that, The particle size of the lithium lanthanum zirconium oxide type solid electrolyte waste mentioned in step 1) is 100~200 mesh.

3. The method for recycling lithium lanthanum zirconium oxide type solid electrolyte waste as described in claim 2, characterized in that, The carbonization reaction described in step 1) is carried out at a pressure of 0.3~1.5MPa for 3~10h.

4. The method for recycling lithium lanthanum zirconium oxide type solid electrolyte waste as described in claim 3, characterized in that, The inorganic base mentioned in step 3) is one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

5. The method for recycling lithium lanthanum zirconium oxide type solid electrolyte waste as described in claim 1, characterized in that, The pyrolysis temperature in step 4) is 85~100℃, and the time is 1~4h.

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