Method for recycling waste positive electrode materials by green vanadium zone-assisted roasting

Abstract

The present invention belongs to the field of recycling waste battery materials, and specifically relates to a method for recycling waste positive electrode materials by green vanadium zone auxiliary roasting, wherein the waste positive electrode materials to be processed and green vanadium are arranged in a pressure-resistant container in a non-mixed manner, and then the container is sealed and subjected to heat preservation and transformation treatment at a temperature of 300 to 600°C, and then the treated waste positive electrode materials are subjected to water immersion treatment to obtain lithium-rich liquid and lithium-extracting slag. The present invention also includes a method for recycling the lithium-extracting slag. The present invention innovatively treats waste positive electrode materials and green vanadium for heat preservation and transformation treatment in the same spatial range in a non-mixed manner, so that the lattice structure of the positive electrode material can be efficiently decomposed based on the gas-solid-liquid three-phase method, the extraction effect and efficiency of lithium can be improved, and the magnetic impurities of the extraction slag can be avoided, so that it can be directly matched with lithium for roasting to obtain high-performance positive electrode active materials. In addition, the green vanadium described in the present invention can be recycled.

Description

Technical Field

[0001] The invention belongs to the field of battery waste recycling, and specifically relates to the field of waste lithium battery material recycling. Background Art

[0002] Due to the extensive use of lithium-ion batteries in electronic devices, electric vehicles and energy storage, the recovery of metals from waste lithium-ion batteries is very fast. And it meets the requirements of sustainable development in terms of resource utilization and environmental protection. At present, pyrometallurgy and hydrometallurgy are the main methods for treating waste lithium-ion batteries. Compared with hydrometallurgical processes, high selectivity, short reaction process and simple treatment process have become the main advantages of pyrometallurgical treatment.

[0003] The prior art discloses a method of using ferrous sulfate to assist in the recovery of positive electrode materials. For example, a Chinese patent document with publication number CN116826224A discloses a method of recovering waste positive electrode materials. The invention belongs to the field of electrode material recovery, and specifically discloses a method for recovering waste positive electrode materials. A mixture containing waste positive electrode materials, additive A and additive B is heat-treated in a pressure-resistant container, and then treated with water to obtain a lithium-containing leaching solution; the additive A is at least one of Na2O2 and KO2; the additive B is at least one of copper hydroxide, KAl(SO4)2·12H2O, and ferrous sulfate heptahydrate; the temperature of the heat treatment is 150-250°C. The present invention can achieve synergy through the process combination, and can improve the mild leaching effect of Li, but the process needs to introduce alkaline components, and the material cost is relatively large. In addition, the system is also prone to introduce magnetic impurities, which affects the direct recovery performance of the material.

[0004] For another example, the Chinese patent document with publication number CN 115584393 A discloses a method for selectively recovering lithium from waste lithium batteries and preparing cobalt ferrite catalysts at the same time, the method comprising: (1) discharging, disassembling and classifying waste lithium cobalt oxide batteries to obtain positive electrode materials, and then subjecting them to high temperature treatment to remove adhesives; (2) drying and screening the lithium cobalt oxide positive electrode powder, mixing it with green vitriol in a certain mass ratio, and roasting it at a certain temperature for a certain time; (3) leaching the roasted product obtained in the first step with deionized water to obtain lithium sulfate leaching solution and leaching residue rich in CoFe2O4; (3) adding ammonia water to the leaching solution obtained in the second step to adjust the pH and filter out iron impurities; (4) adding ammonium carbonate solution to the filtrate obtained in the third step for carbonization, filtering and drying the precipitate to obtain lithium carbonate; (5) loading the leaching residue obtained in the third step with active substances for modification to obtain SCR catalysts. This process requires a relatively high temperature to complete the material conversion.

[0005] In summary, the prior art discloses processes for green vanadium-assisted lithium extraction, all of which involve mixing green vanadium with positive electrode materials to enhance the roasting transformation effect of the materials. However, even so, high temperature or alkaline auxiliary agents are required for transformation, and the processing cost is relatively high. In addition, although the prior art can achieve good lithium extraction effects, magnetic impurities will remain in the lithium extraction slag, making it difficult to directly reuse the leached slag for regeneration. Summary of the invention

[0006] In view of the problems faced by the existing recycling of waste lithium-ion battery positive electrodes, the purpose of the present invention is to provide a method for recycling waste positive electrode materials by green vanadium zone-assisted roasting, aiming to simplify the lithium extraction process of waste positive electrode materials and improve the extraction effect. In addition, the direct regeneration and recovery performance of lithium extraction slag is further realized.

[0007] A method for recycling waste positive electrode materials by green vanadium zone-assisted roasting, wherein the waste positive electrode materials to be processed and green vanadium are arranged in a non-mixed manner in a pressure-resistant container, and then the container is sealed and subjected to heat preservation and transformation treatment at a temperature of 300-600°C, and then the treated waste positive electrode materials are subjected to water immersion treatment to obtain lithium-rich liquid and lithium-extracting slag.

[0008] The present invention innovatively conducts heat preservation transformation treatment on waste positive electrode materials and green vanadium in a non-mixed manner within the same space. This can effectively break down the lattice structure of the positive electrode material based on a gas-solid-liquid three-phase method, improve the extraction effect and efficiency of lithium, avoid magnetic impurities in the extraction slag, and directly prepare high-performance positive electrode active materials by calcining with lithium. In addition, the green vanadium described in the present invention can be recycled.

[0009] In the present invention, the waste positive electrode material is a material stripped from the positive electrode of a waste lithium-ion battery.

[0010] In the present invention, the active material contained in the waste positive electrode material is a lithium-containing active material including at least one element of nickel, cobalt, manganese and iron; further, it can be at least one of lithium nickelate, lithium cobaltate, lithium manganate, nickel-cobalt-manganese ternary material and lithium iron phosphate.

[0011] In the present invention, the content of active material in the waste positive electrode material is above 50 wt.%, more preferably above 80 wt.%, and further preferably 80 to 95 wt.%.

[0012] In the present invention, the weight ratio of the waste positive electrode material to green vanadium is 1:1-5, and can further be 1:2.5-4.5.

[0013] In the present invention, the green vanadium is arranged below the waste positive electrode material in a non-mixed manner.

[0014] In an optional solution of the present invention, the waste positive electrode material is arranged above the green vanadium through a breathable support net. The green vanadium can be arranged at the bottom of the reaction container, and a supporting breathable net is arranged on the green vanadium, which can support the breathable net, and then the system is heated and heat-insulated.

[0015] Preferably, the waste positive electrode material and green vanadium to be treated are arranged in a pressure-resistant container in a non-mixed manner, the pressure of the system is controlled to be negative pressure in advance, and then the sealed container is heated for transformation treatment. The present invention shows that the pressure of the system is controlled at the negative pressure in advance, and then the sealed container is transformed. This can further optimize the partition treatment effect, and can obtain better lithium extraction performance and direct regeneration performance of lithium extraction slag.

[0016] Preferably, the negative pressure is below 0.05 atm, and may further be 0.001 atm to 0.05 atm. The atm refers to atmospheric pressure.

[0017] In the present invention, the transformation temperature is 350-550°C, and can be further 400-450°C in consideration of effect and cost.

[0018] In the present invention, the heat preservation and transformation time is 1 to 5 hours; further, it can be 2 to 4 hours.

[0019] The present invention is based on the green vanadium zoned same-space insulation treatment, which can improve the lattice disintegration effect of waste positive electrodes. It can be based on a simple and mild water immersion treatment, and does not require excessive impurity removal treatment to obtain excellent lithium extraction effects. In addition, it can also avoid the pollution of lithium extraction slag, and can directly regenerate to obtain high-performance regenerated active materials.

[0020] In the present invention, the temperature in the water immersion stage is 20-40°C.

[0021] Preferably, the liquid-to-solid ratio in the water immersion stage is 10 to 30 mL / g.

[0022] Preferably, the immersion time is 10 to 60 minutes, and further can be 20 to 40 minutes.

[0023] In the present invention, the lithium-rich solution is subjected to lithium precipitation treatment to obtain a lithium product. For example, the lithium carbonate product can be recovered by conventional carbonation treatment.

[0024] In the present invention, thanks to the zoning treatment, the direct recycling of lithium extraction slag can be promoted. For example, in an optional solution of the present invention, the lithium extraction slag can be calcined with lithium to obtain a regenerated positive electrode material.

[0025] In the present invention, the regenerated positive electrode material can be obtained by lithium calcination based on conventional means.

[0026] For example, the molar ratio of the lithium element introduced in the lithium roasting stage to the transition metal element in the lithium extraction slag is 1.02-1.05:1.

[0027] The temperature of the lithium calcination is 600 to 800°C, and can be further 650 to 750°C.

[0028] The lithium calcination time is 3 to 7 hours, and can further be 4 to 5 hours.

[0029] In the present invention, the regenerated positive electrode material can be used as a positive electrode active material to prepare a lithium ion battery.

[0030] Beneficial Effects

[0031] The present invention innovatively treats waste positive electrode materials and green vanadium in a non-mixed manner and heatsinks them in the same space, which can improve the extraction effect and efficiency of lithium. In addition, it can also avoid magnetic impurities in the extraction slag, and can directly roast it with lithium to obtain high-performance positive electrode active materials. In addition, the treated green vanadium of the present invention can be recycled. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a cycle diagram for regenerating the positive electrode active material in Example 1. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

[0034] In the present invention, there is no special requirement for the content of active material in the waste lithium-ion battery positive electrode material. Considering the economic efficiency of the process, the content is preferably above 50wt.%. In the following cases, unless otherwise stated, the active content is 85-90wt.%.

[0035] Embodiment 1:

[0036] Step 1: Stripping:

[0037] The waste power nickel cobalt manganese oxide (NCM111) battery was placed in 2 mol / L salt water for 30 hours of discharge treatment, the discharged battery was dried at 85°C, the positive electrode sheet and the negative electrode sheet were disassembled and separated, the positive electrode sheet was immersed in N-methylpyrrolidone, the current collector in the electrode sheet was separated, and the waste positive electrode powder was obtained by filtering, washing and drying;

[0038] Step 2:

[0039] Waste battery powder and green vitriol with a mass ratio of 1:3 were placed in the middle and lower layers of a closed reactor (the middle layer was above the lower layer), and the middle and lower layers were separated by a breathable steel mesh. The sealed container was heated to 400°C and kept at this temperature for 3 hours.

[0040] Step 3: Leaching:

[0041] The treated middle layer material is taken out and placed in water, and leached at room temperature (30±5°C) for 30 minutes (the liquid-to-solid ratio in the leaching stage is 15-20 ml / g) to obtain a solution rich in lithium ions (lithium extraction solution) and lithium extraction slag. The lithium leaching rate is 99.3%. Carbon dioxide is introduced into the lithium extraction solution to obtain lithium carbonate with a purity of 99.1%.

[0042] Step 4: Application:

[0043] The lithium extraction slag and the recovered lithium carbonate are mixed, wherein the molar ratio of lithium to the transition metals (Ni, Co and Mn) in the lithium extraction slag is 1.03-1.05:1, and then calcined in an oxygen atmosphere at a temperature of 700±20°C for 4-4.5 hours to obtain a regenerated positive electrode material.

[0044] The regenerated positive electrode material is used as the active material, and is compounded with conductive carbon black and a binder (PVDF) in a weight ratio of 9:1:1 and coated on the surface of aluminum foil to form a positive electrode. In a glove box, 1M LiPF6 is used as the electrolyte (EC:DEC:EMC=1:1:1), and the diaphragm is a Celgard2400 polypropylene film. With lithium as the counter electrode, the regenerated positive electrode at a rate of 1C at room temperature exhibits a reversible capacity of 190mAh / g, and its capacity retention rate after 100 cycles under this condition can reach 99.1%, reaching or even better than the level of new materials.

[0045] Example 2

[0046] Compared with Example 1, the only difference is that the type of waste positive electrode material is changed. The experimental group is:

[0047] Group A: The waste positive electrode material is the positive electrode material recovered from waste lithium cobalt oxide batteries, the weight ratio of waste battery components to green vanadium is 1:4, and other operations and parameters are the same as those in Example 1. Among them, the lithium leaching rate is 99.2%, and the purity is 99.2%.

[0048] Group B: The waste positive electrode material is the positive electrode material recovered from waste lithium manganese oxide batteries, and other operations and parameters are the same as those in Example 1. Among them, the lithium leaching rate is 99.3% and the purity is 99.3%.

[0049] Example 4

[0050] Compared with Example 1, the only difference is that the processing temperature and time of step 2 are changed, specifically,

[0051] Group A: The treatment temperature was 500°C, the treatment time was 2h, and the other operations and parameters were the same as in Example 1. The lithium leaching rate was 99.5%, and the purity was 99.4%. With lithium as the counter electrode, the positive electrode regenerated at a rate of 1C at room temperature showed a reversible capacity of 191 mAh / g.

[0052] Group B: The treatment temperature was 300°C, the treatment time was 4h, and the other operations and parameters were the same as in Example 1. The lithium leaching rate was 98.8% and the purity was 99.0%. With lithium as the counter electrode, the positive electrode regenerated at a rate of 1C at room temperature showed a reversible capacity of 188mAh / g.

[0053] Example 5

[0054] Compared with Example 1, the only difference is that a horizontal reaction equipment is used, and the waste positive electrode material and green vanadium are independently and parallelly arranged in the reactor in a non-mixed manner. Other operations and parameters are the same as in Example 1.

[0055] The results were: the lithium extraction rate of water immersion was 98.5%, the purity was 98.4%, and with lithium as the counter electrode, the positive electrode regenerated at a rate of 1C at room temperature exhibited a reversible capacity of 182 mAh / g.

[0056] Example 6

[0057] Compared with Example 1, the only difference is that before heating in step 2, the pressure of the reactor is pre-controlled at 0.02-0.05 atm, and then the container is closed and heated to the temperature for insulation transformation. The liquid-to-solid ratio in the immersion stage is 10 ml / g, the immersion time is 20 min, and other operations and parameters are the same as in Example 1.

[0058] The results were: the lithium extraction rate of water immersion was 99.5%, the purity was 99.4%, and with lithium as the counter electrode, the positive electrode regenerated at a rate of 1C at room temperature exhibited a reversible capacity of 193 mAh / g.

[0059] It can be seen from Examples 1 and 6 that setting the system to negative pressure in advance and then heating the transformation can help further optimize the transformation effect, improve the lithium leaching effect and the direct regeneration performance of the lithium extraction slag.

[0060] Comparative Example 1

[0061] Compared with Example 1, the only difference is that green vanadium is not added, and other operations and parameters are the same as Example 1.

[0062] The results showed that the lithium extraction rate of water immersion was 36.4%.

[0063] Comparative Example 2

[0064] Compared with Example 1, the only difference is that the green vitriol is replaced by Fe2(SO4)3·5H2O. Other operations and parameters are the same as those in Example 1.

[0065] In step (4), the lithium leaching rate is 85.3% and the purity is 86.7%.

[0066] Using lithium as the counter electrode, the positive electrode exhibited a reversible capacity of 170 mAh / g at a rate of 1C at room temperature.

[0067] Comparative Example 3

[0068] Compared with Example 1, the only difference is that the roasting temperature is changed to 200° C., and the other operations and parameters are the same as Example 1.

[0069] The lithium leaching rate in step (4) was 70.2%. Using lithium as the counter electrode, the positive electrode regenerated at a rate of 1C at room temperature showed a reversible capacity of 155 mAh / g.

[0070] Comparative Example 4

[0071] Compared with Example 1, the only difference is that the waste positive electrode material and green vanadium are not partitioned but exist in the form of a mixture. Other operations and parameters are the same as Example 1.

[0072] According to the method of Example 1, the lithium leaching rate was 95.7%, and the lithium extraction slag of the material could not be directly utilized.

[0073] Comparative Example 5

[0074] Compared with Example 1, the only difference is that green vanadium is replaced by ferrous sulfate of equal weight, and other operations and parameters are the same as Example 1.

[0075] The test was carried out according to the method of Example 1, and the lithium leaching rate was 80.4%; the positive electrode regenerated at a rate of 1C at room temperature showed a reversible capacity of 162 mAh / g.

Claims

1. A method for recovering waste positive electrode materials by green vanadium zone-assisted roasting, characterized in that: The waste positive electrode materials and green vanadium to be treated are arranged in a non-mixed manner in a pressure-resistant container, and then the container is sealed and subjected to heat preservation and transformation treatment at a temperature of 300 to 600°C. The treated waste positive electrode materials are then immersed in water to obtain lithium-rich liquid and lithium-extracting slag.

2. The method for recovering waste positive electrode materials by green vanadium zone-assisted roasting as claimed in claim 1, characterized in that: The waste positive electrode material is a material stripped from the positive electrode of a waste lithium-ion battery; Preferably, the active material contained in the waste positive electrode material is a lithium-containing active material including at least one element of nickel, cobalt, manganese and iron; preferably at least one of lithium nickelate, lithium cobaltate, lithium manganate, nickel-cobalt-manganese ternary material and lithium iron phosphate; Preferably, the content of active material in the waste positive electrode material is above 50 wt.%, more preferably above 80 wt.%, and further preferably 80 to 95 wt.%.

3. The method for recovering waste positive electrode materials by green vanadium zone-assisted roasting as claimed in claim 1, characterized in that: The weight ratio of the waste positive electrode material to the green vanadium is 1:1-5.

4. The method for recovering waste positive electrode materials by green vanadium zone-assisted roasting as claimed in claim 1, characterized in that: The green vanadium is arranged below the waste positive electrode material in a non-mixed manner.

5. The method for recovering waste positive electrode materials by green vanadium zone-assisted roasting as claimed in claim 4, characterized in that: The waste positive electrode material is arranged above the green vanadium through a breathable supporting net.

6. The method for recovering waste positive electrode materials by green vanadium zone-assisted roasting as claimed in claim 1, characterized in that: The waste cathode material and green vanadium to be treated are arranged in a non-mixed manner in a pressure-resistant container, the pressure of the system is controlled to be negative pressure in advance, and then the sealed container is heated for transformation treatment; Preferably, the negative pressure is below 0.05 atm; Preferably, the heat preservation and transformation time is 1 to 5 hours.

7. The method for recovering waste positive electrode materials by green vanadium zone-assisted roasting as claimed in claim 1, characterized in that: The temperature during the immersion stage is 20-40°C; Preferably, the liquid-to-solid ratio in the water immersion stage is 10 to 30 mL / g; Preferably, the immersion time is 10 to 60 minutes, and further can be 20 to 40 minutes.

8. The method for recovering waste positive electrode materials by green vanadium zone-assisted roasting according to any one of claims 1 to 7, characterized in that: The lithium-rich solution is treated with lithium precipitation to obtain lithium products.

9. The method for recovering waste positive electrode materials by green vanadium zone-assisted roasting as claimed in claim 8, characterized in that: The lithium extraction slag is calcined with lithium to obtain a regenerated positive electrode material; The molar ratio of the lithium element introduced in the lithium roasting stage to the transition metal element in the lithium extraction slag is 1.02-1.05:1; Preferably, the temperature of the lithium calcination is 600-800°C; Preferably, the lithium calcination time is 3 to 7 hours.

10. The method for recovering waste positive electrode materials by green vanadium zone-assisted roasting as claimed in claim 9, characterized in that: The recycled positive electrode material is used as the positive electrode active material to produce a lithium-ion battery.

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