Recycling method of lithium lanthanum zirconium oxide type solid electrolyte waste

Abstract

The invention belongs to the technical field of resource recovery, and provides a lithium lanthanum zirconium oxide type solid electrolyte waste recovery method, which comprises: mixing a lithium lanthanum zirconium oxide type solid electrolyte waste, water and carbon dioxide, and carrying out a carbonization reaction to obtain a lithium-containing liquid and lanthanum oxide zirconium slag; washing and drying the lanthanum oxide zirconium slag; mixing the lithium-containing liquid with inorganic alkali to obtain a lithium-containing purified liquid and alkalized impurity-removed slag; and pyrolyzing the lithium-containing purified liquid to obtain lithium carbonate, thereby completing recovery. According to the method, lithium is extracted through carbonization, the lithium leaching rate reaches 99% or above, lithium carbonate is obtained through impurity removal and lithium precipitation, and the requirement of battery-grade lithium carbonate is met; lanthanum and zirconium exist in the slag in the form of oxide, and can be used as raw materials for synthesizing the lithium lanthanum zirconium oxide type solid electrolyte after being washed and dried. The method avoids traditional acid leaching, roasting and other processes, has the advantages of being easy and convenient to operate, low in energy consumption, environmentally friendly, high in recovery rate and the like, is suitable for industrial large-scale production, and has good social value and economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of resource recovery, and in particular to a method for recovering lithium lanthanum zirconium oxygen type solid electrolyte waste. Background Art

[0002] With the popularization and application of new energy vehicles, lithium-ion batteries, as an effective chemical device for storing electrical energy, have put forward higher requirements for their safety performance and energy density. Compared with other secondary battery systems (such as lead-acid batteries, etc.), lithium-ion batteries have many advantages such as high energy density, long cycle life, and no memory effect. Among them, the emergence of solid-state lithium-ion batteries further makes lithium-ion batteries likely to achieve the unity of high energy density and high safety, and is generally regarded as an inevitable development trend in the field of energy storage batteries in the future. Solid-state electrolytes are the core materials for all-solid-state lithium metal batteries. Garnet-type solid electrolytes (lithium lanthanum zirconium oxide solid electrolytes Li 7 La 3 Zr 2 O 12 (represented by LLZO) has the characteristics of high lithium ion conductivity, wide electrochemical window and good stability to lithium, and has been widely studied in the field of inorganic solid electrolytes and composite polymer electrolytes. These studies are mainly about the exploration of the preparation of lithium lanthanum zirconium oxide type solid electrolytes, in order to provide methods for synthesizing high-performance solid electrolytes to promote the performance of lithium-ion batteries. However, the current research on lithium lanthanum zirconium oxide type solid electrolytes is mainly focused on their preparation and synthesis, surface-interface modification, and development of new composite materials. There are few reports on the research and development of the extraction and resource technology of valuable metals in LLZO type solid electrolytes. The research on the recycling of solid electrolytes and the extraction and reuse of metal materials is not only conducive to resource conservation, high-value reuse of waste valuable metals and environmental protection, but also provides a new expansion for the current research on LLZO type solid electrolytes.

[0003] Invention patent CN113422122A can extract Li embedded in the anode electrode through the high selectivity of LLZTO by applying an external electric field. + and recovered in the form of LiOH, while collecting H 2 This method mainly recovers lithium from LLZTO solid electrolyte, without considering the recovery of lanthanum and zirconium. When electrolysis is used for recycling, the recovery cost is high, which is not conducive to batch processing. In addition, hydrogen will be produced, which poses a safety risk.

[0004] Invention patent CN115584397A disassembles semi-solid batteries, and the obtained materials are divided into positive electrode materials, negative electrode materials, and solid diaphragms. The solid diaphragms are sheared and crushed and then immersed in NMP. The filter residue is mainly lithium lanthanum zirconium titanium oxide. The filter residue is calcined and then acid-leached with sulfuric acid. After filtration, lithium sulfate and lanthanum sulfate filtrate are obtained, as well as filter residue containing zirconium dioxide and titanium dioxide. After the filter residue is washed and dried, it is directly used as a solid electrolyte raw material. Ammonia water is added to the lithium sulfate and lanthanum sulfate filtrate to obtain lanthanum hydroxide precipitation. The lanthanum hydroxide product can be obtained by filtering and washing. This method has a long process flow, a large amount of acid and alkali consumption, and acid leaching also produces toxic and harmful gases.

[0005] Invention patent CN117105262A soaks, ultrasonically cleans and dries a lithium lanthanum zirconium oxide solid electrolyte, and then ball-mills it to obtain solid electrolyte powder; adds it to NMP for calcination, dissolves, stirs and filters the calcined solid electrolyte waste to obtain zirconium-containing residue and filtrate containing lanthanum and lithium; washes, dries, ball-mills and chlorinates the zirconium-containing residue in sequence to obtain zirconium chloride; adjusts the pH of the filtrate containing lanthanum and lithium to alkaline and filters to obtain lithium-containing filtrate and lanthanum hydroxide precipitation residue; washes, dries and calcines the precipitation residue to obtain lanthanum oxide, adds sodium carbonate to the lithium-containing filtrate, and filters and dries to obtain lithium carbonate. This method also uses calcination, acid leaching and other processes, with a long process flow, large acid and alkali consumption, and high production cost. Summary of the invention

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

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

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

[0009] (1) mixing lithium lanthanum zirconium oxide type solid electrolyte waste, water and carbon dioxide and performing a carbonization reaction to obtain a lithium-containing liquid and lanthanum zirconium oxide slag;

[0010] (2) washing and drying the lanthanum zirconium oxide slag;

[0011] (3) mixing the lithium-containing liquid and the inorganic base to obtain a lithium-containing purified liquid and an alkalized impurity-removing slag;

[0012] (4) The lithium-containing purified liquid is pyrolyzed to obtain lithium carbonate, which is then recovered.

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

[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 under a pressure of 0.3 to 1.5 MPa and for a time of 3 to 10 h.

[0016] Preferably, the washing in step (2) is performed by washing with water until the pH value of the washing liquid 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 to 13, and the mixing time is 30 to 60 minutes.

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

[0020] The invention provides a method for recycling lithium lanthanum zirconium oxide type solid electrolyte waste, comprising 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 oxide zirconium slag; washing and drying the lanthanum oxide zirconium slag; mixing the lithium-containing liquid and inorganic alkali to obtain lithium-containing purified liquid and alkalized impurity-removing slag; pyrolyzing the lithium-containing purified liquid to obtain lithium carbonate, and completing the recovery. The invention directly extracts lithium through carbonization, and the lithium leaching rate reaches more than 99%, and then removes impurities and precipitates lithium to obtain lithium carbonate, and its product quality meets the requirements of battery-grade lithium carbonate (YS / T 582-2013); while lanthanum and zirconium are almost not leached, and exist in the slag in the form of oxides, and can be used as raw materials for synthesizing lithium lanthanum zirconium oxide type solid electrolyte after washing and drying. The invention avoids traditional processes such as acid leaching and roasting, and has the advantages of simple operation, low energy consumption, green environmental protection, high recovery rate, etc., is suitable for industrial large-scale production, and has good social value and considerable economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a schematic flow chart of the method for recycling lithium lanthanum zirconium oxygen type solid electrolyte waste. DETAILED DESCRIPTION

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

[0023] (1) mixing lithium lanthanum zirconium oxide type solid electrolyte waste, water and carbon dioxide and performing a carbonization reaction to obtain a lithium-containing liquid and lanthanum zirconium oxide slag;

[0024] (2) washing and drying the lanthanum zirconium oxide slag;

[0025] (3) mixing the lithium-containing liquid and the inorganic base to obtain a lithium-containing purified liquid and an alkalized impurity-removing slag;

[0026] (4) The lithium-containing purified liquid is pyrolyzed to obtain lithium carbonate, which is then recovered.

[0027] In the present invention, the lithium lanthanum zirconium oxide type solid electrolyte waste is derived from the lithium lanthanum zirconium oxide type electrolyte waste dismantled from scrapped solid or semi-solid lithium ion batteries or unqualified products produced when preparing lithium lanthanum zirconium oxide type solid electrolytes; 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 to 200 meshes, more preferably 120 to 180 meshes, and more preferably 140 to 160 meshes.

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

[0029] In the present 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 more preferably 0.6 to 0.8 MPa; the time is preferably 3 to 10 hours, more preferably 4 to 8 hours, and more preferably 5 to 6 hours.

[0030] In the present invention, the reaction principle of step (1) is: lithium lanthanum zirconium oxygen type solid electrolyte and water undergo lithium hydrogen replacement, CO is introduced 2 Under a certain pressure, lithium bicarbonate is generated; the equation is as follows:

[0031] 2Li 7 La 3 Zr 2 O 12 +7H 2 O+14CO 2 = =La 6 Zr 4 O 17 +14LiHCO 3

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

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

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

[0035] In the present invention, after the mixing in step (3) is completed, pressure filtration is performed to obtain the lithium-containing purified liquid and the alkalized impurity-removed residue.

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

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

[0038] The schematic flow diagram of the method for recycling lithium lanthanum zirconium oxygen type solid electrolyte waste of the present invention is as follows Figure 1 shown.

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

[0040] Example 1

[0041] The lithium lanthanum zirconium oxide solid electrolyte was ground by ball mill and passed through a 150 mesh sieve. 1 kg of lithium lanthanum zirconium oxide solid electrolyte powder (Li: 3.7%, La: 30.8%, Zr: 10.3%) was weighed and mixed with 4.5 L of pure water to prepare a slurry. CO was introduced into the mixture. 2 , maintain the pressure at 0.55MPa, react for 6h, and filter press to obtain lithium-containing liquid and lanthanum oxide zirconium slag. The lanthanum oxide zirconium slag is washed with water until the pH value of the washing liquid is neutral, and then dried, and can be directly used as a raw material for synthesizing lithium lanthanum zirconium oxygen type solid electrolyte. Sodium hydroxide is added to the lithium-containing liquid to adjust the pH of the solution to 12.1, react at room temperature for 30min, and filter press to obtain lithium-containing purified liquid and alkaline decontamination slag. The lithium-containing purified liquid is heated to 95℃ and reacted for 2h. After the reaction is complete, 166g of lithium carbonate is obtained by centrifugation, washing, and drying.

[0042] Example 2

[0043] The lithium lanthanum zirconium oxide solid electrolyte was ground by ball mill and passed through a 150 mesh sieve. 1 kg of lithium lanthanum zirconium oxide solid electrolyte powder (Li: 4.0%, La: 33.5%, Zr: 13.7%) was weighed and mixed with 4.7 L of pure water to prepare a slurry. CO was introduced into the mixture. 2, maintain the pressure at 0.6MPa, react for 5h, and filter press to obtain lithium-containing liquid and lanthanum oxide zirconium slag. The lanthanum oxide zirconium slag is washed with water until the pH value of the washing liquid is neutral, and then dried, and can be directly used as a raw material for synthesizing lithium lanthanum zirconium oxygen type solid electrolyte. Potassium hydroxide is added to the lithium-containing liquid to adjust the pH of the solution to 12.0, react at room temperature for 30min, and filter press to obtain lithium-containing purified liquid and alkaline decontamination slag. The lithium-containing purified liquid is heated to 95℃ and reacted for 2h. After the reaction is complete, it is centrifuged, washed, and dried to obtain 179g of lithium carbonate.

[0044] Example 3

[0045] The lithium lanthanum zirconium oxide solid electrolyte was ground by ball mill and passed through a 150 mesh sieve. 1 kg of lithium lanthanum zirconium oxide solid electrolyte powder (Li: 3.5%, La: 30.4%, Zr: 11.7%) was weighed and mixed with 4.3 L of pure water to prepare a slurry. CO was introduced into the mixture. 2 , maintain the pressure at 0.55MPa, react for 6h, and filter press to obtain lithium-containing liquid and lanthanum zirconium oxide slag. The lanthanum zirconium oxide slag is washed with water until the pH value of the washing liquid is neutral, and then dried, and can be directly used as a raw material for synthesizing lithium lanthanum zirconium oxygen type solid electrolyte. Lithium hydroxide is added to the lithium-containing liquid to adjust the pH of the solution to 12.1, react at room temperature for 30min, and filter press to obtain lithium-containing purified liquid and alkaline decontamination slag. The lithium-containing purified liquid is heated to 100℃ and reacted for 2h. After the reaction is complete, 160g of lithium carbonate is obtained by centrifugation, washing, and drying.

[0046] The lanthanum oxide zirconium slag and lithium carbonate obtained in Examples 1 to 3 were subjected to chemical composition analysis. 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 the lithium carbonate obtained in Examples 1 to 3 is shown in Table 2.

[0050] Table 2 Chemical composition of lithium carbonate

[0051]

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

[0053] It can be seen from the above embodiments that the present invention directly extracts lithium through carbonization, the lithium leaching rate reaches more than 99%, and then lithium carbonate is obtained by removing impurities and precipitating lithium, and its 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 form of oxides in the slag, which can be used as a raw material for synthesizing lithium lanthanum zirconium oxygen type solid electrolyte after washing and drying.

[0054] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for recycling lithium lanthanum zirconium oxygen type solid electrolyte waste, characterized in that: It includes the following steps: (1) mixing lithium lanthanum zirconium oxide type solid electrolyte waste, water and carbon dioxide and performing a carbonization reaction to obtain a lithium-containing liquid and lanthanum zirconium oxide slag; (2) washing and drying the lanthanum zirconium oxide slag; (3) mixing the lithium-containing liquid and the inorganic base to obtain a lithium-containing purified liquid and an alkalized impurity-removing slag; (4) The lithium-containing purified liquid is pyrolyzed to obtain lithium carbonate, which is then recovered.

2. The method for recycling lithium lanthanum zirconium oxygen type solid electrolyte waste according to claim 1, characterized in that: The particle size of the lithium lanthanum zirconium oxygen type solid electrolyte waste in step (1) is 100 to 200 meshes.

3. The method for recycling lithium lanthanum zirconium oxygen type solid electrolyte waste according to claim 1 or 2, characterized in that: In step (1), the mass ratio of lithium lanthanum zirconium oxygen type solid electrolyte waste to water is 1:3-6.

4. The method for recycling lithium lanthanum zirconium oxygen type solid electrolyte waste as claimed in claim 3, characterized in that: The carbonization reaction in step (1) is carried out under a pressure of 0.3 to 1.5 MPa and for a time of 3 to 10 hours.

5. The method for recycling lithium lanthanum zirconium oxygen type solid electrolyte waste according to claim 1, characterized in that: In step (2), washing is performed with water until the pH value of the washing solution is neutral.

6. The method for recycling lithium lanthanum zirconium oxygen type solid electrolyte waste according to claim 1 or 4, characterized in that: The inorganic base in step (3) is one or more of sodium hydroxide, potassium hydroxide and lithium hydroxide.

7. The method for recycling lithium lanthanum zirconium oxygen type solid electrolyte waste according to claim 5, characterized in that: The pH after mixing in step (3) is 12 to 13, and the mixing time is 30 to 60 minutes.

8. The method for recycling lithium lanthanum zirconium oxygen type solid electrolyte waste according to claim 1 or 6, characterized in that: The pyrolysis temperature in step (4) is 85-100° C. and the time is 1-4 hours.

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