Method for recovering lithium, lanthanum and zirconium from waste garnet type oxide solid electrolyte

Abstract

The invention belongs to the technical field of battery recovery, discloses a method for recovering lithium, lanthanum and zirconium in a waste garnet type oxide solid electrolyte, and aims to solve the problems that the solid electrolyte is difficult to recover and the lithium recovery rate is low. According to the method, lithium carbonate is efficiently recovered from the waste garnet type oxide solid electrolyte through a sulfuration roasting process, and the recovery rate and the purity both exceed 99%. The residues after lithium extraction are subjected to secondary sintering and sulfuric acid separation treatment and then can be recycled as a solid electrolyte sintering aid containing elements such as lanthanum and zirconium and lanthanum oxide. According to the method, conventional chemicals are adopted, the method is simple and efficient, pollution of the solid-state battery to the environment in the development process is reduced, and raw materials with economic value are recycled.

Description

Technical Field

[0001] The invention relates to the technical field of battery recycling, and in particular to a method for recycling lithium, lanthanum and zirconium in waste garnet-type oxide solid electrolyte. Background Art

[0002] Solid-state batteries have become one of the most promising rechargeable batteries due to their high safety, high energy density and wide electrochemical window. As a key component of solid-state batteries, solid electrolytes facilitate lithium stripping and plating and ensure long-term stable battery cycling. Among various solid-state electrolyte materials, garnet-type oxides are regarded as strong candidates for next-generation electrolyte materials due to their high mechanical strength, good electrochemical stability to lithium metal and high ionic conductivity. However, at low critical current density, lithium dendrites may penetrate garnet-type oxide solid electrolytes, causing battery short circuits. In addition, the synthesis process of garnet pellets is complex and energy-intensive. If they are directly discarded after a short circuit, a large amount of resources will be wasted. Therefore, in order to promote the large-scale application of garnet-based solid-state batteries, it is crucial to conduct basic and forward-looking research related to the recycling of waste garnet-type oxide solid electrolytes.

[0003] At present, the recovery methods of traditional lithium-ion batteries are mainly wet methods and pyrolysis methods, and these technologies are also applicable to the recovery of solid-state batteries. For example, Chinese invention patent CN115584397A discloses a lithium lanthanum zirconium titanium oxide recovery method in a lithium ion semi-solid battery, firstly, a lithium lanthanum zirconium titanium oxide solid electrolyte is placed in an NMP solvent for immersion, and after partial lithium dissolution, the filter residue is calcined and leached with sulfuric acid, and then precipitated with ammonia water to obtain a lanthanum hydroxide product. However, this method can only recover part of the lithium and will produce a large amount of waste residue. Another Chinese invention patent CN117105262A discloses a method for extracting and recovering lanthanum, zirconium and lithium in a lithium lanthanum zirconium oxide solid electrolyte, wherein a lithium lanthanum zirconium oxide solid electrolyte is mixed with NMP and calcined, followed by acid leaching and alkali leaching, and zirconium chloride, lanthanum oxide and lithium carbonate are recovered. This method realizes resource recycling to a certain extent, but the recovery rate is low, and the cost of raw materials is high, which is not conducive to large-scale promotion.

[0004] Therefore, developing a process and technology for efficiently recycling waste garnet-type oxide solid electrolytes has become an important issue that urgently needs attention and research. Summary of the invention

[0005] The purpose of the present invention is to provide a method for efficiently recovering lithium, lanthanum and zirconium from waste garnet-type oxide solid electrolytes in order to address the technical problems of low recovery rate and high cost in existing recycling methods for solid-state batteries.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The present application provides a method for recovering lithium, lanthanum and zirconium from waste garnet-type oxide solid electrolyte, comprising the following steps:

[0008] (1) dismantling the waste solid-state battery and placing it in ethanol to separate the solid electrolyte from the positive and negative electrodes, crushing the separated solid electrolyte into powder, uniformly mixing the solid electrolyte powder with sulfur powder and then calcining it for the first time, adding deionized water to the calcined product for dissolution reaction, and filtering it for the first time to obtain a lithium-containing filtrate and a filter residue containing lanthanum and zirconium;

[0009] (2) After the lithium-containing filtrate is evaporated and concentrated, a sodium carbonate solution is added to precipitate lithium carbonate, and the lithium carbonate precipitate is obtained by a second filtration. The precipitate is washed and dried to obtain lithium carbonate; the filtrate is recycled for further lithium precipitation;

[0010] (3) calcining the lanthanum- and zirconium-containing filter residue obtained in step (1) for a second time, dissolving the calcined product with sulfuric acid, and filtering it for a third time to obtain a lanthanum-containing filtrate and a sintering aid containing lanthanum and zirconium, adding an oxalic acid solution to the filtrate to precipitate lanthanum oxalate, and filtering to obtain lanthanum oxalate;

[0011] (4) calcining the lanthanum oxalate obtained in step (3) for a third time to obtain lanthanum oxide.

[0012] Preferably, in step (1), the solid electrolyte is Li7La3Zr2O 12 , Li 7-x LqCy 2-x Ta x O 12 and Li 7- x LqCy 2-x Nb x O 12 One of them; Li 7-x LqCy 2-x Ta x O 12 Where x is the doping amount of Ta, 0 <x<2;Li 7-x LqCy 2-x Nb x O 12 Where x is the doping amount of Nb, 0 <x<2。

[0013] Preferably, in step (3), the sintering aid containing lanthanum and zirconium is La2Zr2O7, La2Zr 2-x Ta x O 12-6.5x and La2Zr 2-x Nb x O 12-6.5x One of them; La2Zr 2-x Tax O 12-6.5x Where x is the doping amount of Ta, 0 <x<2;La2Zr 2-x Nb x O 12-6.5x Where x is the doping amount of Nb, 0 <x<2。

[0014] Preferably, in step (1), the mass ratio of the solid electrolyte powder to the sulfur powder is 1:(0.1-1).

[0015] Preferably, in step (1), the first calcination is carried out in a tubular furnace, the protective atmosphere is nitrogen, the gas flow rate is 10 to 100 mL / min, the heating rate is 2 to 10° C. / min, the reaction temperature is 400 to 800° C., and the reaction time is 0.25 to 1 h.

[0016] Preferably, in the dissolution reaction of step (1), the solid-liquid ratio is 30 to 50 g / L, and the reaction time is 10 to 60 min.

[0017] Preferably, in step (2), the lithium-containing filtrate is evaporated and concentrated at 90-98°C for 30-120 min. The obtained lithium carbonate precipitate is washed with hot water at 90-98°C and then dried at 100-350°C.

[0018] Preferably, in step (2), the concentration of the sodium carbonate solution is 100 to 300 g / L.

[0019] Preferably, in step (3), the second calcination is carried out in a muffle furnace, the heating rate is 2 to 10°C / min, the reaction temperature is 800 to 1200°C, and the reaction time is 3 to 10 hours.

[0020] Preferably, in step (3), the concentration of sulfuric acid is 0.01 to 0.06 mol / L.

[0021] Preferably, in step (3), the solid-liquid ratio of the calcined product to sulfuric acid is 30 to 50 g / L, and the dissolution time is 10 to 60 min.

[0022] Preferably, in step (3), the concentration of the oxalic acid solution is 50 to 100 g / L.

[0023] Preferably, in step (4), the third calcination is carried out in a tubular furnace, the protective atmosphere is nitrogen, the gas flow rate is 10-100 mL / min, the heating rate is 2-10° C. / min, the reaction temperature is 600-1200° C., and the reaction time is 1-4 h.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] (1) The present invention adopts the process of sulfidation roasting to selectively recover lithium carbonate from waste garnet oxide solid electrolyte, with a lithium ion recovery rate of more than 99% and a purity of more than 99%. At the same time, the lithium slag is recovered as a solid electrolyte sintering aid containing lanthanum, zirconium and other elements, and lanthanum oxide through secondary sintering and sulfuric acid separation. Compared with the prior art, the recovery rate is high, the process is simple, the operating cost is low, and the efficient recovery of resources is fully achieved.

[0026] (2) The materials used in the present invention are all conventional chemicals, which are simple and efficient. They not only reduce the environmental pollution caused by solid-state batteries during their development, but also recycle raw materials with economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0028] Figure 1 It is a process flow chart of the method of the present invention.

[0029] Figure 2 This is a graph of the element leaching rate in the filtrate of the first filtration in step (1) of Example 1 of the present invention.

[0030] Figure 3 This is a diagram of the element content of lithium carbonate in Example 1 of the present invention.

[0031] Figure 4 This is the XRD diagram of lithium carbonate in Example 1 of the present invention.

[0032] Figure 5 This is the XRD diagram of La2Zr2O7 of Example 1 of the present invention.

[0033] Figure 6 This is the XRD diagram of La2O3 in Example 1 of the present invention. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] like Figure 1As shown, this embodiment provides a method for recovering lithium, lanthanum and zirconium from waste garnet-type oxide solid electrolyte, which is specifically carried out according to the following steps:

[0037] (1) Dismantle the waste solid-state battery and place it in ethanol to separate the solid electrolyte from the positive and negative electrodes. Then crush the solid electrolyte into powder and pass it through a 200-mesh sieve to obtain Li7La3Zr2O 12 Solid electrolyte powder was uniformly mixed with sulfur powder at a mass ratio of 1:0.5, placed in a tubular furnace with 10mL / min nitrogen, and the furnace temperature was raised from room temperature to 600℃ at a heating rate of 10℃ / min and kept warm for 1h. After calcination, it was naturally cooled to room temperature. Deionized water was added to the calcined product for dissolution reaction, the solid-liquid ratio of the calcined product to deionized water was 50g / L, and the reaction time was 60min. Figure 2 Figure 2 is the element leaching rate diagram in the filtrate. It can be seen that the leaching rate of Li can reach 99% and the selectivity is close to 100%.

[0038] (2) The mixture was poured into a Buchner funnel for the first filtration. The residue obtained was waste residue containing lanthanum and zirconium. The filtrate was heated to 90°C and kept warm for 60 minutes until Li + The content is ≥30g / L, and then 300g / L of sodium carbonate solution is added to the solution to precipitate lithium, wherein sodium carbonate and Li + The molar ratio of is 1.5: 1. The lithium precipitated product is poured into the Buchner funnel again and filtered for the second time. The filter residue is washed three times with hot water at 90°C and dried to obtain lithium carbonate. Figure 3 This is a diagram of the element content of the obtained lithium carbonate, and the purity of the lithium carbonate is over 99%. Figure 4 This is the XRD diagram of lithium carbonate. The characteristic peaks of the obtained lithium carbonate are completely consistent with those of the standard card.

[0039] (3) The waste residue containing lanthanum and zirconium in step (2) is placed in a muffle furnace for a second calcination. The furnace temperature is raised from room temperature to 1000°C at a heating rate of 10°C / min and kept warm for 6 hours. After the calcination is completed, it is naturally cooled to room temperature. A 0.01 mol / L sulfuric acid solution is added to the calcined product for dissolution reaction. The solid-liquid ratio of the calcined product to the sulfuric acid solution is 50 g / L, and the reaction time is 60 minutes. The mixture is poured into a Buchner funnel for suction filtration. The obtained filter residue is washed with deionized water 3 times and dried to obtain a La2Zr2O7 sintering aid. Figure 5 This is the XRD diagram of La2Zr2O7. The characteristic peaks of the obtained La2Zr2O7 are completely consistent with those of the standard card.

[0040] (4) Add 100 g / L oxalic acid solution to the filtrate of step (3), wherein oxalic acid and La +The molar ratio of is 1.5:1, the product after the reaction is poured into a Buchner funnel for suction filtration, the obtained filter residue is washed 3 times with deionized water and dried. The dried filter residue is placed in a tubular furnace with 10mL / min nitrogen, the furnace temperature is raised from room temperature to 900℃ at a heating rate of 10℃ / min and kept warm for 2h, after calcination, it is naturally cooled to room temperature to obtain La2O3. Figure 6 This is the XRD diagram of La2O3. The characteristic peaks of the obtained La2O3 are completely consistent with those of the standard card.

[0041] Example 2

[0042] like Figure 1 As shown, this embodiment provides a method for recovering lithium, lanthanum and zirconium from waste garnet-type oxide solid electrolyte, which is specifically carried out according to the following steps:

[0043] (1) Dismantle the waste solid-state battery and place it in ethanol to separate the solid electrolyte from the positive and negative electrodes. Then crush the solid electrolyte into powder and pass it through a 200-mesh sieve to obtain Li 6.5 Ln3Z 1.5 Ta 0.5 O 12 Solid electrolyte powder was uniformly mixed with sulfur powder at a mass ratio of 1:1, placed in a tubular furnace with 50mL / min nitrogen, and the furnace temperature was raised from room temperature to 400℃ at a heating rate of 2℃ / min and kept warm for 0.25h. After calcination, it was naturally cooled to room temperature. Deionized water was added to the calcined product for dissolution reaction, the solid-liquid ratio of the calcined product to deionized water was 30g / L, and the reaction time was 10min.

[0044] (2) The mixture was poured into a Buchner funnel for the first filtration. The residue obtained was waste residue containing lanthanum and zirconium. The filtrate was heated to 95°C and kept warm for 30 minutes until Li + The content is ≥30g / L, and then 200g / L sodium carbonate solution is added to the solution to precipitate lithium, wherein sodium carbonate and Li + The molar ratio of is 1.5: 1. The lithium precipitated product is poured into the Buchner funnel again and filtered for the second time. The filter residue is washed three times with hot water at 95°C and dried to obtain lithium carbonate.

[0045] (3) The waste residue containing lanthanum and zirconium in step (1) is placed in a muffle furnace for a second calcination. The temperature is raised from room temperature to 1200°C at a heating rate of 2°C / min and kept at this temperature for 3 hours. After the calcination is completed, it is naturally cooled to room temperature. A 0.03 mol / L sulfuric acid solution is added to the calcined product for dissolution reaction. The solid-liquid ratio of the calcined product to the sulfuric acid solution is 30 g / L, and the reaction time is 10 min. The mixture is poured into a Buchner funnel for suction filtration. The resulting filter residue is washed 3 times with deionized water and dried to obtain Li6.5 Ln3Z 1.5 Ta 0.5 O 12 Sintering aid.

[0046] (4) Add 80 g / L oxalic acid solution to the filtrate of step (3), wherein oxalic acid and La + The molar ratio of is 1.5:1, the product after the reaction is poured into a Buchner funnel for suction filtration, the obtained filter residue is washed 3 times with deionized water and dried. The dried filter residue is placed in a tubular furnace with 50mL / min nitrogen, the furnace temperature is raised from room temperature to 600℃ at a heating rate of 2℃ / min and kept warm for 4h, and after calcination, it is naturally cooled to room temperature to obtain La2O3.

[0047] Example 3

[0048] like Figure 1 As shown, this embodiment provides a method for recovering lithium, lanthanum and zirconium from waste garnet-type oxide solid electrolyte, which is specifically carried out according to the following steps:

[0049] (1) Dismantle the waste solid-state battery and place it in ethanol to separate the solid electrolyte from the positive and negative electrodes. Then crush the solid electrolyte into powder and pass it through a 200-mesh sieve to obtain Li 6.5 Ln3Z 1.5 Nb 0.5 O 12 Solid electrolyte powder was uniformly mixed with sulfur powder at a mass ratio of 1:0.1, placed in a tubular furnace with 100mL / min nitrogen, and the furnace temperature was raised from room temperature to 800℃ at a heating rate of 10℃ / min and kept warm for 0.5h. After calcination, it was naturally cooled to room temperature. Deionized water was added to the calcined product for dissolution reaction, the solid-liquid ratio of the calcined product to deionized water was 40g / L, and the reaction time was 30min.

[0050] (2) The mixture was poured into a Buchner funnel for the first filtration. The residue obtained was waste residue containing lanthanum and zirconium. The filtrate was heated to 98°C and kept warm for 120 minutes until Li + The content is ≥30g / L, and then 100g / L sodium carbonate solution is added to the solution to precipitate lithium, wherein sodium carbonate and Li + The molar ratio of is 1.5: 1. The lithium precipitated product is poured into the Buchner funnel again and filtered for the second time. The filter residue is washed three times with hot water at 98°C and dried to obtain lithium carbonate.

[0051] (3) The waste residue containing lanthanum and zirconium in step (1) is placed in a muffle furnace for a second calcination. The temperature is raised from room temperature to 800°C at a heating rate of 10°C / min and kept at this temperature for 10 hours. After the calcination is completed, it is naturally cooled to room temperature. A 0.06 mol / L sulfuric acid solution is added to the calcined product for dissolution reaction. The solid-liquid ratio of the calcined product to the sulfuric acid solution is 40 g / L, and the reaction time is 30 minutes. The mixture is poured into a Buchner funnel for suction filtration. The obtained filter residue is washed 3 times with deionized water and dried to obtain Li 6.5 LqCy 1.5 Nb 0.5 O 12 Sintering aid.

[0052] (4) Add 50 g / L oxalic acid solution to the filtrate of step (3), wherein oxalic acid and La + The molar ratio of is 1.5:1, the product after the reaction is poured into a Buchner funnel for suction filtration, the obtained filter residue is washed 3 times with deionized water and dried. The dried filter residue is placed in a tubular furnace with 10mL / min nitrogen, the furnace temperature is raised from room temperature to 1200℃ at a heating rate of 5℃ / min and kept warm for 1h, after calcination, it is naturally cooled to room temperature to obtain La2O3.

[0053] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0054] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for recovering lithium, lanthanum and zirconium from waste garnet-type oxide solid electrolytes, characterized in that: The following steps are involved: (1) dismantling the waste solid-state battery and placing it in ethanol to separate the solid electrolyte from the positive and negative electrodes, crushing the separated solid electrolyte into powder, uniformly mixing the solid electrolyte powder with sulfur powder and then calcining it for the first time, adding deionized water to the calcined product for dissolution reaction, and filtering it for the first time to obtain a lithium-containing filtrate and a filter residue containing lanthanum and zirconium; (2) After the lithium-containing filtrate is evaporated and concentrated, a sodium carbonate solution is added to precipitate lithium carbonate, and a precipitate is obtained by a second filtration. The precipitate is washed and dried to obtain lithium carbonate; the filtrate is recycled for further lithium precipitation; (3) calcining the lanthanum- and zirconium-containing filter residue obtained in step (1) for a second time, dissolving the calcined product with sulfuric acid, and filtering it for a third time to obtain a lanthanum-containing filtrate and a sintering aid containing lanthanum and zirconium, adding an oxalic acid solution to the lanthanum-containing filtrate to precipitate lanthanum oxalate, and filtering to obtain lanthanum oxalate; (4) calcining the lanthanum oxalate obtained in step (3) for a third time to obtain lanthanum oxide.

2. The method for recovering lithium, lanthanum and zirconium from waste garnet-type oxide solid electrolyte according to claim 1, characterized in that: In step (1), the solid electrolyte is Li7La3Zr2O 12 , Li 7-x LqCy 2-x Ta x O 12 and Li 7- x LqCy 2-x Nb x O 12 One of them; Li 7-x LqCy 2-x Ta x O 12 Where x is the doping amount of Ta, 0 <x<2;Li 7-x LqCy 2-x Nb x O 12 Where x is the doping amount of Nb, 0 <x<2。 3. The method for recovering lithium, lanthanum and zirconium from waste garnet-type oxide solid electrolyte according to claim 1, characterized in that: In step (3), the sintering aid containing lanthanum and zirconium is La2Zr2O7, La2Zr 2-x Ta x O 12-6.5x and La2Zr 2-x Nb x O 12-6.5x One of them; La2Zr 2-x Ta x O 12-6.5x Where x is the doping amount of Ta, 0 <x<2;La2Zr 2-x Nb x O 12-6.5x Where x is the doping amount of Nb, 0 <x<2。 4. The method for recovering lithium, lanthanum and zirconium from waste garnet-type oxide solid electrolyte according to claim 1, characterized in that: In step (1), the mass ratio of solid electrolyte powder to sulfur powder is 1:(0.1-1).

5. The method for recovering lithium, lanthanum and zirconium from waste garnet-type oxide solid electrolyte according to claim 1, characterized in that: In step (1), the first calcination is carried out in a tubular furnace, the protective atmosphere is nitrogen, the gas flow rate is 10-100 mL / min, the heating rate is 2-10° C. / min, the reaction temperature is 400-800° C., and the reaction time is 0.25-1 h.

6. The method for recovering lithium, lanthanum and zirconium from waste garnet-type oxide solid electrolyte according to claim 1, characterized in that: In the dissolution reaction of step (1), the solid-liquid ratio is 30 to 50 g / L and the reaction time is 10 to 60 min.

7. The method for recovering lithium, lanthanum and zirconium from waste garnet-type oxide solid electrolyte according to claim 1, characterized in that: In step (3), the second calcination is carried out in a muffle furnace, the heating rate is 2-10°C / min, the reaction temperature is 800-1200°C, and the reaction time is 3-10h.

8. The method for recovering lithium, lanthanum and zirconium from waste garnet-type oxide solid electrolyte according to claim 1, characterized in that: In step (3), the concentration of sulfuric acid is 0.01 to 0.06 mol / L.

9. The method for recovering lithium, lanthanum and zirconium from waste garnet-type oxide solid electrolyte according to claim 1, characterized in that: In step (3), the solid-liquid ratio of the calcined product to sulfuric acid is 30 to 50 g / L, and the dissolution time is 10 to 60 min.

10. The method for recovering lithium, lanthanum and zirconium from waste garnet-type oxide solid electrolyte according to any one of claims 1 to 9, characterized in that: In step (4), the third calcination is carried out in a tubular furnace, the protective atmosphere is nitrogen, the gas flow rate is 10-100 mL / min, the heating rate is 2-10° C. / min, the reaction temperature is 600-1200° C., and the reaction time is 1-4 h.

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