A green recycling method of waste battery positive electrode material

Abstract

The application belongs to the technical field of battery recycling, and relates to a green recycling method for positive electrode material of waste batteries, which comprises the following steps: mixing positive electrode active material obtained by separating disassembled waste batteries with an alkali metal compound solution, adding the mixture into a high-pressure reaction kettle for reaction, and obtaining solid and lithium-containing filtrate after solid-liquid separation; performing solid-liquid separation on the lithium-containing filtrate after adjusting the pH value to obtain filter residue and filtrate; purifying the filtrate through ion exchange resin to obtain a purified liquid; performing lithium precipitation reaction on the purified liquid with an alkali metal carbonate, and obtaining lithium carbonate solid after solid-liquid separation; performing slurry adjustment on the lithium carbonate solid, introducing carbon dioxide for carbonization reaction, and obtaining filter liquid after solid-liquid separation, which is heated to precipitate solid to obtain battery-grade lithium carbonate. The application adopts sodium salt or potassium salt and the like to recycle positive electrode active material of waste lithium batteries under high pressure and high temperature conditions, and shows very high lithium recycling efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of battery recycling, and relates to a green recycling method for positive electrode materials of waste batteries. BACKGROUND

[0002] The new energy vehicle industry is developing rapidly, and the sales continue to grow. However, with the large-scale popularization of new energy vehicles, the amount of retired waste batteries is also increasing. In 2023, the global new energy vehicle sales reached 1465.3 million, an increase of 35.4% year-on-year, of which China's new energy vehicle sales reached 949.5 million, accounting for 64.8% of global sales. It is estimated that by 2025, the total amount of retired power batteries in China will reach 116GWh, about 780,000 tons. If these waste batteries are not properly treated, they will cause great harm. Batteries contain heavy metals such as nickel, cobalt, manganese, and electrolyte and other harmful substances. If discarded or disassembled non-standardly, heavy metals will seep into the soil and water, causing long-term environmental pollution, affecting ecological balance and crop growth. For example, a 20-gram mobile phone battery can pollute 1 square kilometer of land for 50 years, and the power battery of a new energy vehicle is larger in size and contains more heavy metals, causing even greater harm. At the same time, in the process of unprofessional treatment, the battery may short circuit, catch fire, or even explode, posing a serious threat to personnel life and property safety. Therefore, the problem of handling of new energy vehicle waste batteries needs to be solved, and a perfect recycling system and treatment technology need to be established to realize effective utilization of resources and environmental protection.

[0003] At present, the main recycling process for waste lithium batteries is fire and wet recovery technology. Fire mainly converts through physical or chemical conversion at high temperature to recover or refine valuable metals from waste lithium ion batteries. The smelting temperature usually reaches about 800℃ or above, and the products obtained are mainly alloys such as nickel-cobalt alloy, iron alloy, etc. In this high-temperature environment, lithium mainly enters the slag phase, which needs to be treated later to recover, resulting in relatively low recovery rate of lithium and high cost, and there are problems such as high energy consumption of high-temperature smelting, high equipment requirements, and great environmental impact of tail gas. For example, Chinese patent CN118610631A discloses a recycling method for waste lithium battery positive electrode materials, which roasts the separated positive electrode active material to remove impurities; then according to the element proportion contained in the target positive electrode material, the required amount of lithium source, hydroxyl aluminum oxide and the positive electrode active material after impurity removal are mixed, and the obtained mixture is roasted to obtain a repaired positive electrode material.

[0004] Wet recovery technology is a mainstream method in the field of metal recovery at present. The advantages of this technology include relatively mild reaction conditions, low tail gas emission and high metal recovery rate, mainly including key processes such as leaching, separation and purification. In the leaching process, it is usually necessary to select appropriate leaching agents such as sulfuric acid, sodium hydroxide, salt solution, etc.; in the separation and purification process, commonly used technologies include precipitation, extraction, electrolysis and adsorption, etc. Chinese patent CN117446769A discloses a method for recycling waste manganese iron lithium phosphate battery, which realizes full component recovery of the positive material of the waste manganese iron lithium phosphate battery by coupling acid leaching, impurity removal by adjusting pH value, extraction and other technologies. However, wet recovery technology needs to use a large amount of strong acid, strong base and strong oxidizing agent, and has problems such as large consumption of acid and alkali, large amount of wastewater discharge and large environmental impact. SUMMARY

[0005] The present application aims at the deficiencies in the prior art and provides a green recovery method for positive material of waste battery, which realizes acid-free and alkali-free green and efficient recovery of valuable metals in waste battery.

[0006] One object of the present application is achieved by the following technical scheme:

[0007] A green recovery method for positive material of waste battery, comprising the following steps:

[0008] S1, discharging, crushing, pyrolysis and fine separation of waste battery to obtain positive active material;

[0009] S2, mixing the positive active material with an alkali metal compound solution and adding it into a high-pressure reaction kettle for reaction, and then performing solid-liquid separation to obtain a solid and a lithium-containing filtrate;

[0010] S3, performing solid-liquid separation after adjusting the pH of the lithium-containing filtrate to obtain a filter residue and a filtrate;

[0011] S4, purifying the filtrate by ion exchange resin to obtain a purified liquid;

[0012] S5, performing lithium precipitation reaction of the purified liquid with an alkali metal carbonate, and then performing solid-liquid separation to obtain lithium carbonate solid and lithium precipitation mother liquor;

[0013] S6, adding the lithium carbonate solid into water to form a slurry, introducing carbon dioxide for carbonization reaction, and then performing solid-liquid separation to obtain a filtrate, which is heated to precipitate a solid to obtain battery-grade lithium carbonate.

[0014] Preferably, the waste battery is a waste lithium battery; further, the waste lithium battery is one or more of a waste ternary lithium battery, a waste iron lithium phosphate battery, a waste lithium cobaltate battery, a waste lithium manganate battery, and a waste lithium titanate battery. Generally, the positive active material of the ternary lithium battery is a ternary compound of nickel-cobalt-manganese (Ni-Mn-Co), the positive active material of the iron lithium phosphate battery is iron lithium phosphate (LiFePO4), the positive active material of the lithium cobaltate battery is lithium cobaltate (LiCoO2), the positive active material of the lithium manganate battery is lithium manganate (LiMn2O4), and the positive active material of the lithium titanate battery is lithium titanate (Li4Ti5O 12 ).

[0015] Before the waste battery is crushed, the waste battery is first discharged to avoid potential risks in the processing process.

[0016] The fine separation includes the steps of secondary crushing, screening, air separation, and gravity separation, and through the fine separation, the positive active material, the negative active material, the negative electrode current collector particles, the positive electrode current collector particles, and the battery shell can be obtained.

[0017] After the battery is discharged, it is crushed, and the crushed material is pyrolyzed at 450-550°C to remove organic substances such as binders; then it is secondary crushed, the crushed material is removed by air separation, and then it is multi-stage screened to separate the positive and negative mixed powder and copper and aluminum particles, and the copper and aluminum particles are separated by gravity separation.

[0018] Preferably, in step S2, the molar ratio of lithium element in the positive active material to alkali metal element in the alkali metal compound solution is 1:1-3.

[0019] Preferably, the concentration of the alkali metal compound solution in step S2 is 0.1-10 mol / L, and further preferably 1-5 mol / L.

[0020] Preferably, the alkali metal compound in step S2 is one or more of sodium sulfate, sodium bisulfate, potassium sulfate, potassium bisulfate, sodium chloride, potassium chloride, sodium nitrate, and potassium nitrate.

[0021] Further preferably, the alkali metal compound is sodium sulfate and / or sodium bisulfate. Using sodium sulfate and / or sodium bisulfate to react with the positive active material has a higher lithium leaching rate.

[0022] Preferably, the reaction pressure in step S2 is 0.5-10 MPa, further preferably 1-5 MPa, for example, it can be 1, 2, 3, 4 or 5 MPa; the reaction temperature is 80-250℃, further preferably 100-220℃, for example, it can be 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210 or 220℃; the reaction time is 0.5-10 h, further preferably 1-5 h, for example, it can be 1, 2, 3, 4 or 5 h.

[0023] Preferably, in step S3, the lithium-containing filtrate is adjusted in pH twice, the first time the pH is adjusted to 5-8, further preferably 6-7; the second time the pH is adjusted to 10-14, further preferably 11-12.

[0024] Preferably, in step S3, after the first adjustment of the pH of the lithium-containing filtrate, the solid-liquid separation is carried out after 30-90 min of reaction, and the filtrate obtained is subjected to the second adjustment of the pH, and the solid-liquid separation is carried out after 30-90 min of reaction.

[0025] The metal impurities in the lithium-containing filtrate are removed by adjusting the pH twice.

[0026] Step S4 specifically comprises: loading the ion exchange resin into an ion exchange column, slowly passing the filtrate to be treated through the ion exchange column, controlling the flow rate of the filtrate to be 1-5 times the volume of the resin per hour, and collecting the effluent as the purified liquid. The ion exchange resin can be exemplified as a cation exchange resin capable of removing calcium and magnesium ions.

[0027] Preferably, in step S5, the molar ratio of lithium elements in the purified liquid to alkali metals in the alkali metal carbonate is 1:1-2.

[0028] Preferably, in step S5, the alkali metal carbonate includes one or more of sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate, further preferably sodium carbonate and / or potassium carbonate.

[0029] Preferably, the time of the lithium precipitation reaction in step S5 is 10-120 min, and the temperature is 50-100℃.

[0030] The main component of the lithium precipitation mother liquor obtained in step S5 is the alkali metal compound in step S2, therefore, the lithium precipitation mother liquor can be returned to step S2 to replace the alkali metal compound solution to mix with the positive active material to carry out the mixing reaction, realizing the recycling of the material.

[0031] In step S6, the lithium carbonate solid is added into water to form a slurry, preferably, the mass ratio of lithium carbonate solid to water is 1:1-20. Preferably, the purity of the carbon dioxide is ≥99.9%. Preferably, the temperature of the carbonation reaction is 20-50 DEG C, and the time is 1-5h. Preferably, the heating temperature is 80-100 DEG C, and the heating time is 30-300min.

[0032] Preferably, the purity of the battery-grade lithium carbonate is ≥99.5%.

[0033] The solid-liquid separation means herein includes centrifugation, filtration, sedimentation, etc.

[0034] Compared with the prior art, the present application has the following beneficial effects:

[0035] 1. The present application uses sodium salt or potassium salt to recover the positive active material of the waste lithium battery under high pressure and high temperature. Since the atomic radius of sodium or potassium is close to that of lithium, under the action of high pressure and high temperature, it is unexpectedly found that in-situ exchange of sodium or potassium atom and lithium atom can be carried out, and lithium atom can be selectively removed from the crystal structure of the positive active material of the waste lithium battery, so as to realize the purpose of preferential lithium extraction.

[0036] 2. The present application uses salt solution high-pressure reaction technology to realize the extraction of lithium element in the positive active material of the waste lithium ion battery. The whole recovery process does not use strong acid chemical reagent, avoids the use of strong corrosive chemical reagent, and is environmentally friendly. Also, high temperature roasting is not used, which reduces energy consumption and shortens the process flow. At the same time, the lithium precipitation mother liquor obtained in the process can be recycled, realizing the recycling of materials, reducing the cost, reducing the wastewater discharge, and further reducing the influence on the environment, which is more green and environmentally friendly.

[0037] 3. The salt solution high-pressure reaction technology used in the present application can achieve a lithium leaching rate of 99%, showing very high lithium recovery efficiency.

[0038] 4. The present application further adjusts the pH value twice to effectively separate the impurity metal ions in the lithium-containing filtrate, and uses cation exchange resin to purify the filtrate, further removes impurities, and improves the purity of lithium carbonate.

[0039] 5. The acid-free and alkali-free recovery method of the positive active material of the waste lithium battery of the present application eliminates high-temperature roasting and complex chemical treatment steps, simplifies the process flow, and is easy to industrialize. DETAILED DESCRIPTION

[0040] The technical solutions of the present application are further described and explained below through specific examples. It should be understood that the specific examples described herein are only used to help understand the present application and are not used to specifically limit the present application. If not specifically stated, the raw materials used in the examples of the present application are all commonly used raw materials in the art, and the methods used in the examples are all conventional methods in the art.

[0041] Example 1

[0042] The green recycling method for waste battery positive electrode material provided in this example includes the following steps:

[0043] (1) Discharge, crush, pyrolysis and fine separation of waste ternary lithium ion battery (positive electrode active material is LiMn 0.15 Co 0.25 Ni 0.6 O) are carried out to obtain positive electrode active material powder, negative electrode graphite powder, copper particles, aluminum particles and metal shell, respectively. The positive electrode active material powder is subjected to subsequent lithium extraction, and the other materials can be directly sold;

[0044] (2) The positive electrode active material powder obtained in step (1) is mixed with 1.5 mol / L sodium sulfate solution according to a molar ratio of lithium element in the positive electrode active material to sodium element in the sodium sulfate solution of 1:1.5, and is added to a high-pressure reaction kettle. The reaction is carried out at 160℃ and 2.0MPa for 2.0h. After the reaction, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate.

[0045] (3) 1mol / L NaOH is added to the lithium-containing filtrate obtained in step (1) to adjust the pH to 6.0, and then the solid-liquid separation is carried out after 20min of reaction to obtain a filter residue and a filtrate #1;

[0046] (4) 1mol / L NaOH is added to the filtrate #1 obtained in step (3) to adjust the pH to 12.0, and then the solid-liquid separation is carried out after 20min of reaction to obtain a filter residue and a filtrate #2;

[0047] (5) The filtrate #2 obtained in step (4) is purified by cation exchange resin, and the flow rate of the filtrate is 3 times the volume of the resin per hour to obtain a purified liquid;

[0048] (6) Then the purified liquid is subjected to lithium precipitation reaction with 2mol / L sodium carbonate solution, and the molar ratio of lithium element in the purified liquid to sodium metal in the sodium carbonate is 1:1.1. The lithium precipitation reaction is carried out at 60℃ for 60min. After solid-liquid separation, lithium carbonate solid and lithium precipitation mother liquor can be obtained. The main component of the lithium precipitation mother liquor is sodium sulfate, so the lithium precipitation mother liquor can be returned to step (2) to replace the sodium sulfate solution and mix with the positive electrode active material powder for reaction;

[0049] (7) Then the lithium carbonate obtained in step (6) is added into water (the mass ratio of lithium carbonate to water is 1:8), and 99.99% carbon dioxide is introduced to perform carbonization reaction (30℃, 2h), and finally heating (90℃, 3h) is performed to precipitate, so that battery-grade lithium carbonate with a purity of 99.7% can be obtained.

[0050] In this embodiment, the leaching rate of lithium in the high-pressure reaction lithium extraction technology of the sodium sulfate solution in step (2) is about 98.5%.

[0051] The leaching rate of lithium = 100%*C*V / m,

[0052] In the formula, C is the concentration of lithium element in the lithium-containing filtrate in step (2) g / L, V is the total volume of the lithium-containing filtrate L, and m is the mass of lithium element in the positive electrode active material powder g.

[0053] Example 2

[0054] The green recycling method of the positive electrode material of the waste battery provided in this embodiment comprises the following steps:

[0055] (1) The waste lithium iron phosphate battery (the positive electrode active material is LiFePO4) is discharged, crushed, pyrolyzed and finely separated, etc. to obtain positive electrode active material powder, negative electrode graphite powder, copper particles, aluminum particles and metal shell, wherein the positive electrode active material powder is subjected to subsequent lithium extraction, and the other materials can be directly sold;

[0056] (2) The positive electrode active material powder obtained in step (1) is mixed with a 2 mol / L potassium sulfate solution according to a molar ratio of lithium element in the positive electrode active material to potassium element in the potassium sulfate solution of 1:1.8, and is added into a high-pressure reaction kettle to react at 180℃ and 2.4 MPa. After 2.5h of reaction, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate.

[0057] (3) 1 mol / L NaOH is added to the lithium-containing filtrate obtained in step (1) to adjust the pH to 7.0, and then the solid-liquid separation is performed after 15 min of reaction to obtain a filter residue and a filtrate #1;

[0058] (4) 1 mol / L NaOH is added to the filtrate #1 obtained in step (3) to adjust the pH to 11.0, and then the solid-liquid separation is performed after 15 min of reaction to obtain a filter residue and a filtrate #2;

[0059] (5) The filtrate #2 obtained in step (4) is purified by cation exchange resin, and the flow rate of the filtrate is 4 times the volume of the resin per hour to obtain a purified liquid;

[0060] (6) Then the purified solution is subjected to a lithium precipitation reaction with 1.5 mol / L potassium carbonate solution, the molar ratio of lithium in the purified solution to potassium in the potassium carbonate solution is 1:1.2, the lithium precipitation reaction is carried out at 70℃, and the reaction time is 50 min. After solid-liquid separation, lithium carbonate solid and lithium precipitation mother liquor can be obtained, and the main component of the lithium precipitation mother liquor is potassium sulfate, so the lithium precipitation mother liquor can be returned to step (2) to replace the potassium sulfate solution to mix with the positive electrode active material powder;

[0061] (7) Then the lithium carbonate obtained in step (6) is added to water to adjust the slurry (the mass ratio of lithium carbonate to water is 1:10), 99.99% carbon dioxide is introduced for carbonation reaction (30℃, 3h), and finally heating (95℃, 3h) is carried out to precipitate, and battery-grade lithium carbonate with a purity of 99.6% can be obtained.

[0062] In this embodiment, the leaching rate of lithium in the high-pressure reaction lithium extraction technology of the potassium sulfate solution in step (2) is about 92.2%.

[0063] Example 3

[0064] The green recycling method for waste battery positive electrode material provided in this embodiment comprises the following steps:

[0065] (1) Discharge, crush, pyrolysis and fine separation of waste ternary lithium ion battery (positive electrode active material is LiMn 0.15 Co 0.25 Ni 0.6 O) are carried out to obtain positive electrode active material powder, negative electrode graphite powder, copper particles, aluminum particles and metal shell, respectively. The positive electrode active material powder is subjected to subsequent lithium extraction, and the other materials can be directly sold;

[0066] (2) The positive electrode active material powder obtained in step (1) is mixed with 1 mol / L potassium sulfate solution according to the molar ratio of lithium in the positive electrode active material to potassium in the potassium sulfate solution is 1:1.4, and is added to a high-pressure reaction kettle, and is reacted at 80℃ and 0.5 MPa. After 6.0h of reaction, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate.

[0067] (3) 1 mol / L NaOH is added to the lithium-containing filtrate obtained in step (1) to adjust the pH to 8.0, and then the solid-liquid separation is carried out after 25 min of reaction to obtain a filter residue and a filtrate #1;

[0068] (4) 1 mol / L NaOH is added to the filtrate #1 obtained in step (3) to adjust the pH to 14.0, and then the solid-liquid separation is carried out after 25 min of reaction to obtain a filter residue and a filtrate #2;

[0069] (5) The filtrate #2 obtained in step (4) is purified by passing through a cation exchange resin, and the flow rate of the filtrate passing through the resin is 5 times the volume of the resin per hour, to obtain a purified solution;

[0070] (6) The purified solution is then subjected to a lithium precipitation reaction with a 2.5 mol / L potassium carbonate solution, and the molar ratio of lithium in the purified solution to potassium in the potassium carbonate solution is 1:1.3. The lithium precipitation reaction is carried out at 80°C for 80 minutes. After solid-liquid separation, lithium carbonate solid and a lithium precipitation mother liquor are obtained. The main component of the lithium precipitation mother liquor is potassium sulfate, so the lithium precipitation mother liquor can be returned to step (2) to replace the potassium sulfate solution and mixed with the positive electrode active material powder.

[0071] (7) The lithium carbonate obtained in step (6) is then slurried by adding water (the mass ratio of lithium carbonate to water is 1:9), carbonated by passing in 99.99% carbon dioxide (30°C, 1.5h), and finally precipitated by heating (85°C, 3h) to obtain battery-grade lithium carbonate with a purity of 99.8%.

[0072] In this embodiment, the leaching rate of lithium in the high-pressure reaction lithium extraction technology of the potassium sulfate solution in step (2) is about 78.5%.

[0073] Example 4

[0074] The green recycling method for waste battery positive electrode material provided in this embodiment includes the following steps:

[0075] (1) A waste ternary lithium ion battery (the positive electrode active material is LiMn 0.15 Co 0.25 Ni 0.6 O) is discharged, crushed, pyrolyzed, and finely separated, etc. to obtain positive electrode active material powder, negative electrode graphite powder, copper particles, aluminum particles, and a metal shell, respectively. The positive electrode active material powder is subjected to subsequent lithium extraction, and the other materials can be directly sold.

[0076] (2) The positive electrode active material powder obtained in step (1) is mixed with a 3 mol / L potassium bisulfate solution according to a molar ratio of lithium in the positive electrode active material to potassium in the potassium bisulfate solution of 1:1.6, and is added to a high-pressure reaction kettle. The reaction is carried out at 250°C and 4 MPa. After 0.5h of reaction, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate.

[0077] (3) 2 mol / L NaOH is added to the lithium-containing filtrate obtained in step (1) to adjust the pH to 5.5, and then the solid-liquid separation is carried out after 15 minutes of reaction to obtain a filter residue and a filtrate #1.

[0078] (4) To the filtrate #1 obtained in step (3), 2 mol / L NaOH was added again to adjust the pH to 10, and then the solid-liquid separation was performed after 15 min of reaction to obtain a filter residue and a filtrate #2;

[0079] (5) The filtrate #2 obtained in step (4) was purified by a cation exchange resin, and the flow rate of the filtrate through the resin was 2 times the volume of the resin per hour to obtain a purified solution;

[0080] (6) Then, the purified solution was subjected to a lithium precipitation reaction with a 2.5 mol / L potassium carbonate solution, and the molar ratio of lithium in the purified solution to potassium in the potassium carbonate solution was 1:1.3. The lithium precipitation reaction was performed at 90°C for 80 min, and after the solid-liquid separation, lithium carbonate solid and a lithium precipitation mother liquor were obtained. The main component of the lithium precipitation mother liquor was potassium sulfate;

[0081] (7) Then, the lithium carbonate obtained in step (6) was slurried in water (the mass ratio of lithium carbonate to water was 1:11), and 99.99% carbon dioxide was introduced for carbonation reaction (30°C, 3h). Finally, heating (92°C, 4h) was performed to precipitate, and battery-grade lithium carbonate with a purity of 99.9% was obtained.

[0082] In this embodiment, the leaching rate of lithium in the high-pressure reaction of the potassium bisulfate solution in step (2) was about 85.7%.

[0083] Example 5

[0084] The green recycling method for the positive electrode material of the waste battery provided in this embodiment includes the following steps:

[0085] (1) A waste ternary lithium ion battery (the positive electrode active material is LiMn 0.15 Co 0.25 Ni 0.6 O) was discharged, crushed, pyrolyzed, and finely separated, and positive electrode active material powder, negative electrode graphite powder, copper particles, aluminum particles, and a metal shell were obtained, respectively. The positive electrode active material powder was subjected to subsequent lithium extraction, and the other materials could be directly sold;

[0086] (2) The positive electrode active material powder obtained in step (1) was mixed with a 4 mol / L sodium bisulfate solution according to a molar ratio of lithium in the positive electrode active material to sodium in the sodium bisulfate solution of 1:1.8, and was added to a high-pressure reaction kettle. The reaction was performed at 220°C and 3 MPa, and after 5h of reaction, the slurry was subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate.

[0087] (3) 2 mol / L NaOH was added to the lithium-containing filtrate obtained in step (1) to adjust the pH to 7.5, and then the solid-liquid separation was performed after 15 min of reaction to obtain a filter residue and a filtrate #1;

[0088] (4) To the filtrate #1 obtained in step (3), 2 mol / L NaOH was added again to adjust the pH to 12.5, and then the solid-liquid separation was performed after 15 min of reaction to obtain a filter residue and a filtrate #2;

[0089] (5) The filtrate #2 obtained in step (4) was purified by a cation exchange resin, and the flow rate of the filtrate through the resin was 23 times the volume of the resin per hour to obtain a purified solution;

[0090] (6) Then, the purified solution was subjected to a lithium precipitation reaction with a 3 mol / L sodium carbonate solution, and the molar ratio of lithium in the purified solution to sodium in the sodium carbonate was 1:1.5. The lithium precipitation reaction was performed at 90°C for 90 min, and after the solid-liquid separation, lithium carbonate solid and a lithium precipitation mother liquor were obtained. The main component of the lithium precipitation mother liquor was sodium sulfate;

[0091] (7) Then, the lithium carbonate obtained in step (6) was slurried in water (the mass ratio of lithium carbonate to water was 1:12), and 99.99% carbon dioxide was introduced for carbonation reaction (30°C, 2.5 h). Finally, heating (92°C, 3.5 h) was performed to precipitate, and battery-grade lithium carbonate with a purity of 99.8% was obtained.

[0092] In this example, the leaching rate of lithium in the sodium bisulfate solution high-pressure reaction lithium extraction technology of step (2) was about 95.8%.

[0093] Example 6

[0094] The green recycling method of the spent battery cathode material of Example 6 is different from that of Example 1 in that step (2) of Example 6 is: the cathode active material powder obtained in step (1) is mixed with a 1.5 mol / L sodium bisulfate solution according to a molar ratio of lithium in the cathode active material to sodium in the sodium bisulfate solution of 1:1.5, and is added to a high-pressure reaction kettle for reaction at 160°C and 2.0 MPa. After 2.0 h of reaction, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate. The other steps are the same as those of Example 1.

[0095] In this example, the leaching rate of lithium in the sodium bisulfate solution high-pressure reaction lithium extraction technology of step (2) was about 94.3%.

[0096] Example 7

[0097] The green recycling method of the waste battery cathode material of Example 7 is different from that of Example 1 in that step (2) of Example 7 is that the cathode active material powder obtained in step (1) is mixed with a 1.5 mol / L potassium sulfate solution at a molar ratio of lithium in the cathode active material to potassium in the potassium sulfate solution of 1:1.5, added to a high-pressure reaction kettle, and reacted at 160°C and 2.0 MPa for 2.0 h. After the reaction, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate. The other steps are the same as those of Example 1.

[0098] In this example, the leaching rate of lithium in the potassium sulfate solution high-pressure reaction lithium extraction technology of step (2) is about 91.4%.

[0099] Example 8

[0100] The green recycling method of the waste battery cathode material of Example 8 is different from that of Example 1 in that step (2) of Example 8 is that the cathode active material powder obtained in step (1) is mixed with a 1.5 mol / L potassium bisulfate solution at a molar ratio of lithium in the cathode active material to potassium in the potassium bisulfate solution of 1:1.5, added to a high-pressure reaction kettle, and reacted at 160°C and 2.0 MPa for 2.0 h. After the reaction, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate. The other steps are the same as those of Example 1.

[0101] In this example, the leaching rate of lithium in the potassium bisulfate solution high-pressure reaction lithium extraction technology of step (2) is about 83.6%.

[0102] Example 9

[0103] The green recycling method of the waste battery cathode material of Example 9 is different from that of Example 1 in that step (2) of Example 9 is that the cathode active material powder obtained in step (1) is mixed with a 1.5 mol / L sodium chloride solution at a molar ratio of lithium in the cathode active material to sodium in the sodium chloride solution of 1:1.5, added to a high-pressure reaction kettle, and reacted at 160°C and 2.0 MPa for 2.0 h. After the reaction, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate. The other steps are the same as those of Example 1.

[0104] In this example, the leaching rate of lithium in the sodium chloride solution high-pressure reaction lithium extraction technology of step (2) is about 80.7%.

[0105] Example 10

[0106] The green recycling method of the waste battery cathode material of Example 10 is different from that of Example 1 in that step (2) of Example 10 is that the cathode active material powder obtained in step (1) is mixed with a 1.5 mol / L sodium nitrate solution at a molar ratio of lithium in the cathode active material to sodium in the sodium nitrate solution of 1:1.5, added to a high-pressure reaction kettle, and reacted at 160°C and 2.0 MPa for 2.0 h. After the reaction, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate. The other steps are the same as those of Example 1.

[0107] In this example, the leaching rate of lithium in the sodium nitrate solution high-pressure reaction lithium extraction technology of step (2) is about 81.5%.

[0108] Comparative Example 1

[0109] Comparative Example 1 is different from Example 1 in that step (2) of Comparative Example 1 is specifically that the cathode active material powder obtained in step (1) is mixed with a 1.5 mol / L sodium sulfate solution at a molar ratio of lithium in the cathode active material to sodium in the sodium sulfate solution of 1:1.5, added to a high-pressure reaction kettle, and reacted at 40°C and 2.0 MPa for 2.0 h. After the reaction, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate.

[0110] The other steps are the same as those of Example 1.

[0111] In this example, the leaching rate of lithium in the sodium sulfate solution high-pressure reaction lithium extraction technology of step (2) is about 20.8%.

[0112] Comparative Example 2

[0113] Comparative Example 2 is different from Example 1 in that step (2) of Comparative Example 2 is specifically that the cathode active material powder obtained in step (1) is mixed with a 1.5 mol / L sodium sulfate solution at a molar ratio of lithium in the cathode active material to sodium in the sodium sulfate solution of 1:1.5, added to a high-pressure reaction kettle, and reacted at 160°C under normal pressure for 2.0 h. After the reaction, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate.

[0114] The other steps are the same as those of Example 1.

[0115] In this example, the leaching rate of lithium in the sodium sulfate solution high-pressure reaction lithium extraction technology of step (2) is about 35.9%.

[0116] Aspects, embodiments, features, of the present application should be considered illustrative and not restrictive in all aspects, and the scope of the present application is only defined by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed application.

[0117] In the preparation method of the present application, the order of the steps is not limited to the order listed, and for those of ordinary skill in the art, changes in the order of the steps without creative effort are within the scope of the present application. In addition, two or more steps or actions can be performed simultaneously.

[0118] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the scope of the application. Various modifications or changes in the described embodiments can be made by those skilled in the art, or equivalents can be substituted, without departing from the spirit of the present application. It is intended that the present application embrace all such modifications and changes and, accordingly, the application should not be limited by the foregoing description, but should be defined only by the following claims.

Claims

1. A green recycling method for positive electrode materials of waste batteries, characterized in that, Includes the following steps: S1. Discharge, crush, pyrolyze, and finely separate waste batteries to obtain positive electrode active materials; S2. The positive electrode active material is mixed with an alkali metal compound solution and added to a high-pressure reactor for reaction. The reaction pressure is 0.5~10MPa, the reaction temperature is 80~250℃, and the reaction time is 0.5~10h. After solid-liquid separation, a solid and a lithium-containing filtrate are obtained. S3. After adjusting the pH of the lithium-containing filtrate, solid-liquid separation is performed to obtain filter residue and filtrate. S4. The filtrate is purified by passing it through an ion exchange resin to obtain a purified solution. S5. The purified solution is reacted with alkali metal carbonate to precipitate lithium. After solid-liquid separation, solid lithium carbonate and lithium precipitation mother liquor are obtained. S6. Solid lithium carbonate is added to water to form a slurry, carbon dioxide is introduced to carry out a carbonation reaction, the filtrate obtained by solid-liquid separation is then heated to precipitate solids, and battery-grade lithium carbonate is obtained. In step S2, the molar ratio of lithium element in the positive electrode active material to alkali metal element in the alkali metal compound solution is 1:1~3; the alkali metal compound is one or more of sodium sulfate, sodium bisulfate, potassium sulfate, potassium bisulfate, sodium chloride, potassium chloride, sodium nitrate, and potassium nitrate. In step S3, the pH of the lithium-containing filtrate is adjusted twice. The pH is adjusted to 5-8 for the first time, and the solid-liquid separation is performed after reacting for 30-90 minutes. The pH of the obtained filtrate is adjusted to 10-14 for the second time, and the solid-liquid separation is performed after reacting for 30-90 minutes.

2. The green recycling method for waste battery cathode materials according to claim 1, characterized in that, The waste batteries are waste lithium batteries; The waste lithium batteries are one or more compounds selected from waste ternary lithium batteries, waste lithium iron phosphate batteries, waste lithium cobalt oxide batteries, waste lithium manganese oxide batteries, and waste lithium titanate batteries.

3. The green recycling method for waste battery positive electrode material according to claim 1, characterized in that, The concentration of the alkali metal compound solution in step S2 is 0.1~10 mol / L.

4. A green recycling method for waste battery cathode materials according to claim 1, characterized in that, In step S5, the molar ratio of lithium in the purified solution to alkali metal in the alkali metal carbonate is 1:1~2.

5. A green recycling method for waste battery positive electrode materials according to claim 1, characterized in that, Alkali metal carbonates include one or more of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

6. A green recycling method for waste battery cathode materials according to claim 1, characterized in that, The lithium precipitation reaction in step S5 takes 10-120 minutes and is carried out at a temperature of 50-100°C.

7. A green recycling method for waste battery positive electrode materials according to claim 1, characterized in that, In step S6, the mass ratio of lithium carbonate solid to water is 1:1 to 20.

8. A green recycling method for waste battery positive electrode materials according to claim 1, characterized in that, In step S6, the purity of the introduced carbon dioxide is ≥99.9%.

9. A green recycling method for waste battery positive electrode materials according to claim 1, characterized in that, In step S6, the carbonization reaction is carried out at a temperature of 20~50℃ for 1~5 hours.

10. A green recycling method for waste battery positive electrode materials according to claim 1, characterized in that, In step S6, the heating temperature is 80~100℃ and the heating time is 30~300min.