High-pressure wet chemical flash repair and recovery method for waste lithium cobalt oxide battery positive electrode material

Abstract

The application discloses a high-pressure wet-chemical flash repair and recovery method for a positive electrode material of a waste lithium cobalt oxide battery, and comprises the following steps: S1, soaking the waste lithium cobalt oxide battery in a sodium chloride solution, disassembling after small-current discharging, and obtaining a waste lithium cobalt oxide positive electrode sheet; S2, soaking the waste lithium cobalt oxide positive electrode sheet in an organic solvent, removing the binder and separating the positive electrode material, then washing with ethanol and drying to obtain a pretreated waste lithium cobalt oxide positive electrode powder; S3, grinding and refining the waste lithium cobalt oxide positive electrode powder, mixing the waste lithium cobalt oxide positive electrode powder with water, adding a reaction aid and an organic lithium source, stirring and mixing, and then moving into a reaction kettle; S4, placing the reaction kettle in an oven for heating reaction; S5, taking out the reaction kettle, filtering after cooling the solution, washing with a washing solvent and drying to obtain a primary repaired lithium cobalt oxide positive electrode powder; and the problems that the existing technology cannot reform damaged lattices and promote lattice orientation are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of waste lithium battery positive material recycling, in particular to a high-pressure wet chemical flash repair and recycling method for waste lithium cobalt oxide battery positive material. BACKGROUND

[0002] Lithium cobalt oxide is an important material widely used in lithium-ion batteries and other fields. With the popularity of electronic products and the rise of electric vehicles, the demand for lithium cobalt oxide is increasing. However, due to its scarcity and environmental pollution risk, the recycling of lithium cobalt oxide becomes particularly important. There are three main methods for recycling waste lithium cobalt oxide positive material: ① hydrometallurgy; ② pyrometallurgy; ③ direct regeneration of positive material.

[0003] The current focus of lithium cobalt oxide recycling is mainly pyrometallurgy or hydrometallurgy, but pyrometallurgy requires high-temperature treatment, which is harsh on equipment and has high energy consumption. Most hydrometallurgical processes use inorganic strong acids for leaching, which releases sulfur dioxide and harmful nitrogen-containing gases, polluting the environment. Unlike indirect recycling processes such as pyrometallurgy and hydrometallurgy, the hydrothermal direct recycling method does not require leaching of metal elements, does not require quantification of lithium sources, has mild process conditions, and effectively shortens the repair time of failed positive electrodes at high pressure and high temperature, making it extremely promising for efficient recycling of waste lithium cobalt oxide batteries. The traditional hydrothermal recycling method generally focuses on lithium loss and repair of long-cycled positive materials. SUMMARY

[0004] The present application provides a high-pressure wet chemical flash repair and recycling method for waste lithium cobalt oxide battery positive material, which solves the problem of the prior art that damaged crystal lattices cannot be reorganized and promotes crystal lattice orientation.

[0005] To solve the technical problem, the present application provides the following technical solution:

[0006] The high-pressure wet chemical flash repair and recycling method for waste lithium cobalt oxide battery positive material comprises the following steps:

[0007] S1, soaking the waste lithium cobalt oxide battery in a sodium chloride solution, disassembling after small current discharge, and obtaining waste lithium cobalt oxide positive electrode sheets;

[0008] S2, soaking the waste lithium cobalt oxide positive electrode sheets in an organic solvent, removing the binder and separating the positive material, then washing with ethanol and drying to obtain pre-treated waste lithium cobalt oxide positive powder;

[0009] S3, grinding the waste lithium cobalt oxide positive powder and mixing it with water, adding a reaction aid and an organic lithium source, stirring and mixing, and then transferring into a reaction kettle;

[0010] S4, the reaction kettle is placed in the oven to heat the reaction;

[0011] S5, the reaction kettle is taken out, the solution is cooled and filtered, and then washed with a washing solvent and dried to obtain a preliminarily repaired lithium cobalt oxide positive electrode powder;

[0012] S6, the preliminarily repaired lithium cobalt oxide positive electrode powder is subjected to flash joule heating to obtain a repaired lithium cobalt oxide positive electrode material.

[0013] By using the method of soaking in an organic solvent, and then using a simple hydrothermal reaction, the reaction time is effectively shortened in a high-pressure and high-temperature environment, and a reaction aid is added to assist in reforming the damaged lattice structure and further repairing the damaged structure, and flash joule heating is further used to remove impurities and adjust the material morphology, so as to improve the electrochemical performance of the waste lithium cobalt oxide positive electrode material.

[0014] Preferably, the concentration of the sodium chloride solution in step 1 is 5wt%, and the voltage of the waste lithium cobalt oxide battery after discharge is between 1.6-2.2V.

[0015] Preferably, the type of organic solvent used in step S2 is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone or dimethyl sulfoxide.

[0016] Preferably, the solid-liquid ratio of the waste lithium cobalt oxide positive electrode sheet to the organic solvent in step S2 is 1:5-1:10mg / mL.

[0017] Preferably, the mass-volume ratio of the waste lithium cobalt oxide powder to water in step S3 is 1:20-1:80g / ml.

[0018] Preferably, the reaction aid in step S3 is selected from one or more of polyvinyl alcohol, polyacrylate, polyacrylamide, methyl amyl alcohol, triethanolamine, dioctyloxy diphenyl phosphate, ethylenediamine tetramethylene phosphonic acid or quaternary ammonium salt, and the addition mass is 5-20wt% of the waste lithium cobalt oxide powder.

[0019] By using the reaction aid assisted hydrothermal reaction, the damaged lattice can be effectively reformed and the lattice can be guided in a favorable direction while the lithium is supplemented, so as to realize the efficient repair of the waste lithium cobalt oxide.

[0020] Preferably, the organic lithium source in step S3 is selected from at least one of lithium ethoxide, lithium phenoxide, lithium biphenyl, butyl lithium, lithium naphthalene, lithium trisazylmethyl sulfonate or 5-sulfo-1,3-benzenedicarboxylic acid monolithium, and the addition mass is 5-20wt% of the mass of the waste lithium cobalt oxide positive electrode powder.

[0021] Preferably, the heating temperature in step S4 is 140-250℃, and the reaction time is 4-6h.

[0022] Preferably, the washing solvent in step S5 is ethanol, and the drying temperature is between 80-120℃.

[0023] Preferably, the flash Joule heat time in step S6 is 10-25s, and the temperature is 1000-2000℃.

[0024] Compared with the prior art, the present application has the following advantages:

[0025] The method of the present application removes the binder components in the battery powder by using the organic solvent soaking method, and then through the hydrothermal reaction, while adding a certain amount of organic lithium source and reaction aids to obtain the preliminary repaired lithium cobalt oxide cathode material, and then combining with the flash Joule heat to obtain the final repaired lithium cobalt oxide cathode material.

[0026] The present application uses the organic solvent soaking method, and then uses the simple hydrothermal reaction to effectively shorten the reaction time in the high-pressure and high-temperature environment, and adds the reaction aids to assist in the reconstruction of the damaged lattice structure and the further repair of the damaged structure, and combines with the flash Joule heat to further remove the impurities and adjust the material morphology structure, so as to improve the electrochemical performance of the waste lithium cobalt oxide cathode material.

[0027] Meanwhile, unlike the high-temperature solid-phase recovery, the flash Joule heat used in the present application can save a large amount of energy consumption, and achieve the purpose of efficient impurity removal and morphology reconstruction in a short time, not only reduces the influence on the environment, but also makes the direct recovery process of the waste lithium cobalt oxide have commercial application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0028] The drawings described herein are used to provide further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings:

[0029] Figure 1 The process flow chart of the high-pressure wet chemical recovery method for the waste lithium cobalt oxide battery cathode material;

[0030] Figure 2 The SEM images of the waste lithium cobalt oxide, the preliminary repaired lithium cobalt oxide, and the final repaired lithium cobalt oxide; wherein, Figure 2 (a)、 Figure 2 (d) is the initial waste lithium cobalt oxide; Figure 2 (b)、 Figure 2 (e) is the preliminary repaired lithium cobalt oxide; Figure 2 (c)、 Figure 2 (f) is the final repaired lithium cobalt oxide;

[0031] Figure 3To recover the waste lithium cobalt oxide and the electrochemical performance of the final recovered lithium cobalt oxide at 1C; wherein, Figure 3 (a) is the first cycle charge-discharge curve; Figure 3 (b) is the cycle performance curve at 3-4.35V, 1C. DETAILED DESCRIPTION

[0032] To make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below with examples, the illustrative embodiments of the present application and the description thereof are only used to explain the present application, and do not limit the present application.

[0033] Example 1

[0034] As shown in the following table, the present application provides a high-pressure wet chemical flash repair recovery method for recovering the positive electrode material of waste lithium cobalt oxide battery with the aid of an auxiliary agent, which is implemented by the following steps: Figure 1 Step 1

[0035] The waste lithium iron phosphate battery is soaked in a 5wt% sodium chloride solution and discharged to about 2V, then cut and disassembled, and the positive electrode sheet is separated and cut into small pieces and soaked in NMP solvent, the solid-liquid ratio is 1:10, and the removed material is dried in a 110°C oven for two hours to obtain lithium cobalt oxide powder.

[0036] Step 2

[0037] 1g of waste lithium cobalt oxide positive electrode powder is dispersed in 50mL of deionized water, 8wt% of polyvinyl alcohol and 10% of lithium phenate are added, the mixture is stirred at a speed of 200r / min at room temperature and transferred to a reaction kettle.

[0038] Step 3

[0039] The reaction kettle is placed in a 160°C oven and left for 4h.

[0040] Step 4

[0041] The cooled reaction solution is filtered and washed with ethanol, then dried in an 80°C oven for 3 hours to obtain the recovered lithium cobalt oxide powder.

[0042] Step 5

[0043] The preliminary repaired lithium cobalt oxide powder is subjected to 10s flash joule heating at 1000°C.

[0044] Step 6

[0045] The recovered lithium cobalt oxide powder is assembled into a button half-cell and subjected to charge-discharge test, as shown in the following table:

[0046] Figure 3 ​As shown, the first circle discharge gram capacity is stable at 146 mAh / g at 3-4.35 V at 1C rate, and the cycle retention rate is 75% after 200 cycles.

[0047] Example 2

[0048] The embodiment 1 of the present application provides a high-pressure wet chemical flash repair and recovery method for recovering waste positive electrode material of lithium cobalt oxide battery with the aid of an auxiliary agent, which is implemented through the following steps:

[0049] Step 1

[0050] The waste lithium iron phosphate battery is soaked in a 5wt% sodium chloride solution and discharged to about 2V, then cut and disassembled, and the positive electrode sheet is separated and cut into small pieces and soaked in NMP solvent, the solid-liquid ratio is 1:10, and the removed material is dried in a 110°C oven for two hours to obtain lithium cobalt oxide powder.

[0051] Step 2

[0052] 2g of waste lithium cobalt oxide positive electrode powder is dispersed in 50mL of deionized water, 10wt% of polyvinyl alcohol and 12% of lithium phenate are added, and the mixture is stirred at a speed of 200r / min at room temperature and then transferred to a reaction kettle.

[0053] Step 3

[0054] The reaction kettle is placed in a 160°C oven and left for 4h.

[0055] Step 4

[0056] The cooled reaction solution is filtered and washed with ethanol, and then dried in an 80°C oven for 3 hours to obtain the recovered lithium cobalt oxide powder.

[0057] Step 5

[0058] The preliminarily repaired lithium cobalt oxide powder is subjected to 15s flash joule heating at 1000°C.

[0059] Step 6

[0060] The recovered lithium cobalt oxide powder is assembled into a button half-cell and subjected to charge-discharge test, and the first circle discharge gram capacity is stable at 146 mAh / g at 3-4.35 V at 1C rate, and the cycle retention rate is 76% after 200 cycles.

[0061] Example 3

[0062] The embodiment 1 of the present application provides a high-pressure wet chemical flash repair and recovery method for recovering waste positive electrode material of lithium cobalt oxide battery with the aid of an auxiliary agent, which is implemented through the following steps:

[0063] Step 1

[0064] The waste lithium iron phosphate battery is soaked in a 5wt% sodium chloride solution and discharged to about 2V, then cut and disassembled, the positive plate is separated, cut into small pieces, soaked with NMP solvent, the solid-liquid ratio is 1:10, the removed material is dried in an oven at 110°C for two hours to obtain lithium cobaltate powder.

[0065] Step 2

[0066] 3g of waste lithium cobaltate positive electrode powder is dispersed in 60mL of deionized water, 12wt% of polyvinyl alcohol and 13% of lithium phenate of the mass of the waste lithium cobaltate positive electrode powder are added, and the mixture is stirred at a speed of 200r / min at room temperature and transferred to a reaction kettle.

[0067] Step 3

[0068] The reaction kettle is placed in an oven at 140°C for 6h.

[0069] Step 4

[0070] The cooled reaction solution is filtered and washed with ethanol, and then dried in an oven at 80°C for 3h to obtain the recovered lithium cobaltate powder.

[0071] Step 5

[0072] The primary repaired lithium cobaltate powder is subjected to 20s flash joule heating at 1000°C.

[0073] Step 6

[0074] The recovered lithium cobaltate powder is assembled into a button half-cell and subjected to charge-discharge test, and the first circle discharge specific capacity is measured to be 148mAh / g at 3-4.35V and 1C rate, and the 200 cycle retention rate is 72%.

[0075] Example 4

[0076] The example 1 of the present application provides a high-pressure wet chemical flash repair and recovery method for recovering waste lithium cobaltate battery positive electrode material assisted by an auxiliary agent, which is implemented by the following steps:

[0077] Step 1

[0078] The waste lithium iron phosphate battery is soaked in a 5wt% sodium chloride solution and discharged to about 2V, then cut and disassembled, the positive plate is separated, cut into small pieces, soaked with dimethyl sulfoxide solvent, the solid-liquid ratio is 1:5, the removed material is dried in an oven at 110°C for two hours to obtain lithium cobaltate powder.

[0079] Step 2

[0080] 1.5 g of waste lithium cobalt oxide positive electrode powder was dispersed in 50 mL of deionized water, 8 wt% of polyacrylate and 10% of lithium phenol were added to the mass of the waste lithium cobalt oxide positive electrode powder, and the mixture was stirred at a speed of 200 r / min at room temperature and then transferred to a reaction kettle.

[0081] Step 3

[0082] The reaction kettle was placed in a 140°C oven and left for 6 h.

[0083] Step 4

[0084] The cooled reaction solution was filtered and washed with ethanol, and then dried in a 120°C oven for 3 h to obtain the recovered lithium cobalt oxide powder.

[0085] Step 5

[0086] The primary repaired lithium cobalt oxide powder was subjected to 15 s flash Joule heating at 2000°C.

[0087] Step 6

[0088] The recovered lithium cobalt oxide powder was assembled into a button-type half-cell and subjected to charge-discharge tests. The first cycle discharge specific capacity was stable at 140 mAh / g at 3-4.35 V and 1C rate, and the cycle retention rate was 74% after 200 cycles.

[0089] Example 5

[0090] The embodiment 1 of the present application provides a high-pressure wet chemical flash repair and recovery method for recovering waste lithium cobalt oxide battery positive electrode material with the aid of an auxiliary agent, which is implemented by the following steps:

[0091] Step 1

[0092] The waste lithium iron phosphate battery was soaked in a 5 wt% sodium chloride solution and discharged to about 2 V, then cut and disassembled, and the positive electrode sheet was separated and cut into small pieces and soaked in N,N-dimethylacetamide solvent, with a solid-liquid ratio of 1:8. The removed material was dried in a 110°C oven for two hours to obtain lithium cobalt oxide powder.

[0093] Step 2

[0094] 2.5 g of waste lithium cobalt oxide positive electrode powder was dispersed in 50 mL of deionized water, 5 wt% of polyacrylate and 20% of lithium ethoxide were added to the mass of the waste lithium cobalt oxide positive electrode powder, and the mixture was stirred at a speed of 200 r / min at room temperature and then transferred to a reaction kettle.

[0095] Step 3

[0096] The reaction kettle was placed in a 160°C oven and left for 5 h.

[0097] Step 4

[0098] The cooled reaction solution was filtered and washed with ethanol, and then placed in an 80°C oven to dry for 3 hours to obtain the recovered lithium cobalt oxide powder.

[0099] Step 5

[0100] The preliminarily repaired lithium cobalt oxide powder was subjected to 15s flash joule heating at 1500°C.

[0101] Step 6

[0102] The recovered lithium cobalt oxide powder was assembled into a button-type half-cell, and subjected to charge-discharge test, and the first circle discharge specific capacity was stable at 138mAh / g at 3-4.35V, 1C rate, and the 200 cycle retention rate was 78%.

[0103] Example 6

[0104] The embodiment 1 of the present application provides a high-pressure wet chemical flash repair recovery method for recovering waste lithium cobalt oxide battery positive electrode material assisted by an auxiliary agent, which is implemented through the following steps:

[0105] Step 1

[0106] The waste lithium iron phosphate battery was soaked in a 5wt% sodium chloride solution and discharged to about 2V, then cut and disassembled, and the positive electrode sheet was separated and cut into small pieces, soaked in N,N-dimethylformamide solvent, the solid-liquid ratio was 1:10, and the removed material was dried in a 110°C oven for two hours to obtain lithium cobalt oxide powder.

[0107] Step 2

[0108] 1g of waste lithium cobalt oxide positive electrode powder was dispersed in 80mL of deionized water, 20wt% of polyacrylate and 5% of lithium ethoxide were added, and the mixture was stirred at a speed of 200r / min at room temperature and then transferred to a reaction kettle.

[0109] Step 3

[0110] The reaction kettle was placed in a 250°C oven and left to stand for 4h.

[0111] Step 4

[0112] The cooled reaction solution was filtered and washed with ethanol, and then placed in an 80°C oven to dry for 3 hours to obtain the recovered lithium cobalt oxide powder.

[0113] Step 5

[0114] The preliminarily repaired lithium cobalt oxide powder was subjected to 25s flash joule heating at 1000°C.

[0115] Step 6

[0116] The recovered lithium cobalt oxide powder was assembled into a button-shaped half battery, and charge-discharge test was conducted, and the first circle discharge gram capacity was stable at 135 mAh / g at 3-4.35V, 1C rate, and the 200 cycle retention rate was 72%.

[0117] As shown in Figure 2 the above embodiment 1, as shown in Figure 2 , Figure 2 a、 Figure 2 d is the SEM image of the initial waste lithium cobalt oxide; Figure 2 b、 Figure 2 e is the preliminary repaired lithium cobalt oxide; Figure 2 c、 Figure 2 f is the final repaired lithium cobalt oxide. It can be seen that after repair, the purpose of efficient impurity removal and morphology reconstruction is achieved in a short time.

[0118] Figure 3 The electrochemical performance of the waste lithium cobalt oxide of embodiment 1 and the final repaired lithium cobalt oxide at 1C, Figure 3 (a) is the first circle charge-discharge curve, and the first circle discharge gram capacity is stable at 146 mAh / g at 3-4.35V, 1C rate, Figure 3 (b) is the cycle performance curve at 3-4.35V, 1C, and the 200 cycle retention rate is 75%. It can be seen that after repair, the specific capacity and cycle performance of lithium cobalt oxide are significantly improved.

[0119] The above structure and performance improvement is due to the use of organic solvent soaking method, and then using simple hydrothermal reaction, effectively shortening the reaction time in high pressure and high temperature environment, and adding reaction aids to assist in repairing the damaged lattice structure and further repairing the damaged structure. The structure is further repaired, and the flash johr heat is further removed and the material morphology structure is adjusted to improve the electrochemical performance of the waste lithium cobalt oxide positive material.

[0120] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and does not limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A high-voltage wet chemical flash remediation and recycling method for cathode materials from waste lithium cobalt oxide batteries, characterized in that, Includes the following steps: S1. Immerse the waste lithium cobalt oxide battery in sodium chloride solution, and disassemble it after discharging with a small current to obtain the waste lithium cobalt oxide positive electrode sheet. S2. The waste lithium cobalt oxide positive electrode sheet is soaked in an organic solvent to remove the binder and separate the positive electrode material. Then it is washed with ethanol and dried to obtain pretreated waste lithium cobalt oxide positive electrode powder. S3. Grind the waste lithium cobalt oxide cathode powder into a fine powder and mix it with water. Add the reaction aid and organic lithium source, stir and mix, and then transfer it into a reaction vessel. The mass-to-volume ratio of the waste lithium cobalt oxide cathode powder to water is 1:20 to 1:80 g / ml. The reaction aid is selected from polyvinyl alcohol or polyacrylate and is added at 5-20 wt% of the waste lithium cobalt oxide cathode powder. S4. Place the reactor in an oven and heat it to react; S5. Remove the reactor, cool the solution and filter it, wash it with washing solvent and dry it to obtain the preliminarily repaired lithium cobalt oxide cathode powder. S6. The pre-repaired lithium cobalt oxide cathode powder is subjected to flash Joule heating to obtain the repaired lithium cobalt oxide cathode material. The flash Joule heating time is 10–25 s, and the temperature is 1000–2000 °C.

2. The high-voltage wet chemical flash remediation and recycling method for waste lithium cobalt oxide battery cathode materials according to claim 1, characterized in that, The concentration of the sodium chloride solution mentioned in step 1 is 5wt%, and the voltage of the waste lithium cobalt oxide battery after discharge is between 1.6-2.2V.

3. The high-voltage wet chemical flash remediation and recycling method for waste lithium cobalt oxide battery cathode materials according to claim 1, characterized in that, The organic solvent used for soaking in step S2 is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone or dimethyl sulfoxide.

4. The high-voltage wet chemical flash remediation and recycling method for waste lithium cobalt oxide battery cathode materials according to claim 1, characterized in that, In step S2, the solid-liquid ratio of the waste lithium manganese oxide positive electrode sheet to the organic solvent is 1:5-1:10 mg / mL.

5. The high-voltage wet chemical flash remediation and recycling method for waste lithium cobalt oxide battery cathode materials according to claim 1, characterized in that, The organic lithium source mentioned in step S3 is selected from at least one of lithium ethanol, lithium phenolate, lithium biphenyl, butyl lithium, lithium naphthylene, lithium trichloromethyl sulfonate, or lithium 5-sulfo-1,3-phthalic acid monolithium, and its added mass is 5-20 wt% of the mass of waste lithium cobalt oxide cathode powder.

6. The high-voltage wet chemical flash remediation and recycling method for waste lithium cobalt oxide battery cathode materials according to claim 1, characterized in that, In step S4, the heating temperature is 140–250°C, and the reaction time is 4–6 h.

7. The high-voltage wet chemical flash remediation and recycling method for waste lithium cobalt oxide battery cathode materials according to claim 1, characterized in that, The washing solvent in step S5 is ethanol, and the drying temperature is between 80-120°C.

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