Normal pressure recycling method for waste lithium manganate positive electrode material

Abstract

The application discloses a kind of normal pressure recovery regeneration method of waste old lithium manganate positive material, comprising the following steps: S1, waste old lithium manganate battery is soaked in sodium chloride aqueous solution, after disassembling, waste old lithium manganate positive pole piece is obtained after being discharged;S2, waste old lithium manganate positive pole piece is soaked in organic solvent to remove binder and make positive material separate out, then using ethanol is washed and dried, and pretreated waste old lithium manganate positive powder is obtained;S3, pretreated waste old lithium manganate positive powder is dispersed in high-boiling point organic solvent and is moved into reactor, lithium source and reducing agent are added, after being fully stirred and mixed, mixed solution is heated and stirred, after reaction, filtering is carried out, using ethanol is washed and dried, and re-lithiation type lithium manganate powder is obtained;S4, re-lithiation type lithium manganate powder is ball milled with lithium source and ethanol and dried;S5, the material after drying is calcined in air atmosphere, and regenerated lithium manganate powder is obtained, in-situ lithium supplement and in-situ lattice repair are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of waste lithium battery positive material recycling, and particularly relates to a waste lithium manganate positive material normal-pressure recycling regeneration method. BACKGROUND

[0002] Lithium manganate is one of the main positive materials of low-speed electric vehicle batteries on the market at present, and has a very large market share. The existing lithium manganate positive material recycling mainly recycles waste lithium manganate for resource utilization, such as converting it into high-value compounds or synthesizing it into new lithium manganate materials through pyrometallurgical and hydrometallurgical processes, and repairing defects of waste lithium manganate to realize regeneration. The advantage of pyrometallurgical recycling is that it does not need complex pretreatment steps, and can directly crush and sinter into an alloy to recycle metals, but the high energy consumption and high pollution in the process and the low economy of lithium manganate are the biggest problems existing in the development of this process in the field of waste lithium manganate battery recycling. Hydrometallurgical recycling avoids the high energy consumption of pyrometallurgical recycling, but the battery needs to be pretreated before recycling, such as discharging, disassembling, crushing, and separating the waste battery to separate the positive electrode, negative electrode, separator, and current collector, obtaining the failed positive electrode black powder, and then using acid, alkali, or microorganisms to leach the metal elements in the positive electrode black powder into the solution, and recycling the metal elements by precipitation method, or re-preparing the positive electrode material. The metal recovery rate of hydrometallurgical recycling is relatively high, but a large amount of acid or alkali reagents are inevitably used, which has a big environmental problem.

[0003] The lithium battery recycling technology that is concerned at present is direct recycling, which is different from the indirect recycling process of pyrometallurgical and hydrometallurgical recycling. Direct recycling does not leach metal elements, but directly supplements lithium and repairs the structure of the positive electrode material after long cycle. The process flow of direct recycling is relatively simple, does not need to use a large amount of acid and alkali reagents, and has relatively low energy consumption, so it develops rapidly, but the direct recycling method has relatively high requirements for the quality of the raw material black powder. At present, the direct recycling method mainly includes solid phase method, hydrothermal method, and electrochemical method. The solid phase method supplements lithium and repairs the lattice by adding lithium source and high-temperature sintering, but the lithium loss of different waste positive electrode black powders is uncertain, so each batch of positive electrode black powder needs to be quantitatively supplemented with lithium. The liquid phase method does not need to be quantitatively supplemented with lithium source, and the defects of the waste positive electrode black powder can be repaired by providing appropriate lithium source solution and suitable temperature. The whole process is mild, and the lithiumization time of the failed positive electrode is effectively shortened through the liquid phase process, which can significantly reduce energy consumption and greenhouse gas emissions. However, the liquid phase method is difficult to repair the lattice structure distortion, so it has broad prospects to combine the liquid phase method with the solid phase method to realize efficient recycling of waste lithium manganate batteries. SUMMARY

[0004] The present application provides a waste lithium manganate positive material normal-pressure recycling regeneration method, which solves the problem of defects in lithium manganate existing in the prior art.

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

[0006] A normal pressure recycling and regeneration method of waste lithium manganate positive electrode material, comprising the following steps:

[0007] S1, soaking the waste lithium manganate battery in a sodium chloride aqueous solution, disassembling after discharging, and obtaining waste lithium manganate positive electrode sheets;

[0008] S2, soaking the waste lithium manganate positive electrode sheets in an organic solvent to remove the binder and separate the positive electrode material, then washing with ethanol and drying to obtain pretreated waste lithium manganate positive electrode powder;

[0009] S3, dispersing the pretreated waste lithium manganate positive electrode powder in a high-boiling-point organic solvent and transferring into a reactor, adding a first lithium source and a reducing agent, fully stirring and mixing, heating and stirring the mixed solution, filtering after reaction, washing with ethanol and drying to obtain a re-lithiated lithium manganate powder;

[0010] S4, ball-milling the re-lithiated lithium manganate powder with a second lithium source and ethanol and drying;

[0011] S5, calcining the dried material in an air atmosphere to obtain a regenerated lithium manganate powder.

[0012] The present application can realize in-situ lithium supplement and in-situ lattice repair, realize the recycling and regeneration of waste lithium manganate, and improve the performance. Compared with the existing solid phase method and liquid phase method, the obtained lithium manganate has fewer defects, lower cost, and simpler process flow. The performance of the lithium manganate repaired by this method is close to that of commercial lithium manganate material.

[0013] 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.

[0014] Preferably, the solid-liquid ratio of the waste lithium manganate positive pole piece to the organic solvent in step S2 is 1:10-1:20 mg / mL, the soaking time is between 0.5 h and 1 h, and the soaking temperature is between 50 DEG C and 100 DEG C; the total content of aluminum, copper, iron and other metal impurities in the waste lithium manganate powder is not higher than 1000 ppm.

[0015] Preferably, the first lithium source in step S3 is one or more of lithium oxalate, lithium hydroxide, lithium carbonate, lithium nitrate, lithium acetate, lithium borohydride and lithium aluminum hydride, and the added amount is 8-15 wt% of the mass of the waste lithium manganate powder.

[0016] Preferably, the reducing agent in step S3 is one or more of citric acid, formic acid, oxalic acid and ascorbic acid, and the added amount is 10-15 wt% of the mass of the waste lithium manganate powder.

[0017] The selection of the lithium source, the reducing agent and the reaction temperature and reaction time has a great influence on the specific capacity and material morphology of the regenerated lithium manganate, and through the selection of the lithium source, the reducing agent and the reaction temperature and reaction time, the purposes of in-situ lithium supplement and in-situ lattice repair can be achieved.

[0018] Preferably, the high-boiling organic solvent in step S3 is one or more of dimethyl carbonate DBE, octyl acetate, n-octanol or ethylene glycol, and the added amount is 10-20 mL of organic solvent per gram of waste lithium manganate.

[0019] The present application uses a high-boiling organic solvent as a reaction solvent, and high temperature can increase a large amount of reaction heat to shorten the reaction time, and the solvent is not easy to volatilize and can be recycled.

[0020] Preferably, the heating temperature in step S3 is 130-180 DEG C, the heating and stirring time is 1-5 h, and the stirring speed is 100-400 r / min.

[0021] Preferably, the second lithium source in step S4 is one or more of lithium oxalate, lithium hydroxide, lithium carbonate, lithium nitrate, lithium acetate, lithium borohydride and lithium aluminum hydride, and the added amount is 5-10 wt% of the mass of the lithium-manganese powder.

[0022] The calcination of S4 and the atmospheric organic phase treatment of step S3 are synergistically repaired, which can achieve in-situ lithium supplement and in-situ lattice repair, and the purposes of recycling and regenerating the waste lithium manganate and improving the performance can be achieved.

[0023] Preferably, the calcination temperature in step S5 is 700-1000 DEG C, and the calcination time is 1-5 h.

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

[0025] This invention proposes a method for the atmospheric pressure recycling and regeneration of waste lithium manganese oxide cathode materials. The method involves removing the binder components from the retired lithium manganese oxide black powder obtained by dismantling waste lithium manganese oxide batteries through organic solvent soaking, and then adding a certain amount of lithium source and reducing agent to the powder using a high-boiling-point organic solvent as the reaction solvent. The reaction is carried out under atmospheric pressure to obtain relithiated lithium manganese oxide black powder, which is then mixed with a lithium source and ball-milled, and finally sintered in air to obtain pure repaired and regenerated lithium manganese oxide material.

[0026] This invention uses a high-boiling-point organic solvent as the reaction solvent. High temperature can increase the heat of reaction by a large amount, thereby shortening the reaction time. The solvent is not easily volatilized and can be recycled. The subsequent ball milling makes the lithium manganese oxide powder and lithium source fully and uniformly mixed. Finally, the lithium manganese oxide cathode material that can be directly repaired and regenerated is obtained by high-temperature calcination.

[0027] Compared with existing solid-phase and liquid-phase methods, the synergistic repair method used in this invention yields lithium manganese oxide with fewer defects, lower cost, and simpler process. The performance of lithium manganese oxide repaired by this method is also close to that of commercial lithium manganese oxide materials. Attached Figure Description

[0028] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0029] Figure 1 This is a process flow diagram of the present invention;

[0030] Figure 2 Here is a scanning electron microscope image of the waste lithium manganese oxide material obtained in Comparative Example 1;

[0031] Figure 3 This is a scanning electron microscope image of the regenerated lithium manganese oxide material from Example 1;

[0032] Figure 4 This is a comparison of the electrochemical performance of recycled lithium manganese oxide material and waste lithium manganese oxide material in Example 1 and Comparative Example 1. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0034] Example 1

[0035] like Figure 1 As shown, Embodiment 1 of the present invention provides a method for the atmospheric pressure recycling and regeneration of waste lithium manganese oxide cathode materials, which is implemented through the following steps:

[0036] Step 1: soak the waste lithium manganate battery in a 5wt% sodium chloride aqueous solution and discharge to about 2V, then cut and disassemble; Step 2: after separating the positive electrode sheet, cut it into small pieces and soak it in N-methyl pyrrolidone, the solid-liquid ratio is 1:10, the soaking time is 0.5h, the soaking temperature is 100℃, and the removed material is dried in a 110℃ oven for 2h to obtain lithium manganate powder, the carbon content of which is 2.5wt%, and the total metal impurities are 120ppm.

[0037] Step 3: 5g of waste lithium manganate positive electrode powder is dispersed in 50mL of n-octanol solution and moved into the reactor, 8wt% of lithium carbonate and 10wt% of citric acid based on the weight of the waste lithium manganate positive electrode powder are added, the stirring speed is 300r / min, the mixture is fully stirred, heated at 130℃ for 3h, after the reaction is completed, it is naturally cooled, filtered, washed with ethanol, and dried to obtain a re-lithiated lithium manganate powder.

[0038] Step 4: mix the re-lithiated lithium manganate powder with 5wt% of lithium carbonate based on its weight, then move it into a stainless steel ball mill tank, add an appropriate amount of ethanol, and ball mill at 400r / min for 10h.

[0039] Step 5: after the ball-milled material is dried, it is moved into a muffle furnace and calcined at 800℃ for 2h in an air atmosphere to obtain a regenerated lithium manganate powder.

[0040] The regenerated lithium manganate is assembled into a button-type half cell and subjected to charge-discharge test to measure the charge-discharge performance at 1C rate.

[0041] Example 2

[0042] The example 2 of the present application provides a method for recovering and regenerating waste lithium manganate positive electrode material under normal pressure, which is implemented by the following steps:

[0043] Step 1: soak the waste lithium manganate battery in a 5wt% sodium chloride aqueous solution and discharge to about 2V, then cut and disassemble; Step 2: after separating the positive electrode sheet, cut it into small pieces and soak it in N-methyl pyrrolidone, the solid-liquid ratio is 1:10, the soaking time is 0.5h, the soaking temperature is 100℃, and the removed material is dried in a 110℃ oven for 2h to obtain lithium manganate powder, the carbon content of which is 2.5wt%, and the total metal impurities are 120ppm.

[0044] Step 3: 5g of waste lithium manganate positive electrode powder is dispersed in 50mL of n-octanol solution and moved into the reactor, 8wt% of lithium carbonate and 10wt% of citric acid based on the weight of the waste lithium manganate positive electrode powder are added, the stirring speed is 300r / min, the mixture is fully stirred, heated at 130℃ for 3h, after the reaction is completed, it is naturally cooled, filtered, washed with ethanol, and dried to obtain a re-lithiated lithium manganate powder.

[0045] Step 4: The re-lithiated lithium manganate powder was mixed with 5wt% lithium carbonate of its weight, then moved into a stainless steel ball mill tank, and an appropriate amount of ethanol was added, and ball milled at 400r / min for 10h.

[0046] Step 5: After the ball-milled material was dried, it was moved into a muffle furnace and calcined at 800℃ for 2h in an air atmosphere to obtain a regenerated lithium manganate powder.

[0047] The regenerated lithium manganate was assembled into a button-type half cell, and charge-discharge test was performed to measure the charge-discharge performance at 1C rate.

[0048] Example 3

[0049] The example 3 of the present application provides a normal-pressure recovery and regeneration method for waste lithium manganate positive electrode material, which is implemented through the following steps:

[0050] Step 1: The waste lithium manganate battery was soaked in a 5wt% sodium chloride aqueous solution and discharged to about 2V, then cut and disassembled, Step 2: After the positive electrode sheet was separated, it was cut into small pieces and soaked in N,N-dimethylformamide, the solid-liquid ratio was 1:15, the soaking time was 0.75h, the soaking temperature was 75℃, and the removed material was dried in an oven at 110℃ for 2h to obtain lithium manganate powder, the carbon content of which was 2.5wt%, and the total metal impurities were 120ppm.

[0051] Step 3: 5g of waste lithium manganate positive electrode powder was dispersed in 50mL of n-octanol solution and moved into a reactor, 10wt% of lithium oxalate and 12wt% of formic acid of the weight of the waste lithium manganate positive electrode powder were added, and the mixture was fully stirred at a rotation speed of 400r / min, heated at 130℃ for 3h, naturally cooled after the reaction was completed, filtered, washed with ethanol, and dried to obtain a re-lithiated lithium manganate powder.

[0052] Step 4: The re-lithiated lithium manganate powder was mixed with 8wt% lithium hydroxide of its weight, then moved into a stainless steel ball mill tank, and an appropriate amount of ethanol was added, and ball milled at 400r / min for 10h.

[0053] Step 5: After the ball-milled material was dried, it was moved into a muffle furnace and calcined at 700℃ for 5h in an air atmosphere to obtain a regenerated lithium manganate powder.

[0054] The regenerated lithium manganate was assembled into a button-type half cell, and charge-discharge test was performed to measure the charge-discharge performance at 1C rate.

[0055] Example 4

[0056] The example 4 of the present application provides a normal-pressure recovery and regeneration method for waste lithium manganate positive electrode material, which is implemented through the following steps:

[0057] Step 1: the waste lithium manganate battery is soaked in a 5wt% sodium chloride aqueous solution and discharged to about 2V, and then cut and disassembled, step 2: after the positive plate is separated, it is cut into small pieces and soaked in N,N-dimethylacetamide, the solid-liquid ratio is 1:10, the soaking time is 0.5h, the soaking temperature is 90℃, and the removed material is dried in an oven at 110℃ for 2h to obtain lithium manganate powder, the carbon content of which is 2.5wt%, and the total metal impurities are 120ppm.

[0058] Step 3: 5g of waste lithium manganate positive electrode powder is dispersed in 80mL of n-octanol solution and moved into a reactor, 15wt% of lithium hydroxide and 15wt% of oxalic acid based on the weight of the waste lithium manganate positive electrode powder are added, and fully stirred and mixed at a rotation speed of 300r / min, heated at 130℃ for 5h, naturally cooled after the reaction is completed, filtered, washed with ethanol, and dried to obtain a re-lithiated lithium manganate powder.

[0059] Step 4: the re-lithiated lithium manganate powder is mixed with 10wt% of lithium oxalate based on the weight of the re-lithiated lithium manganate powder, and then moved into a stainless steel ball mill tank, and an appropriate amount of ethanol is added, and ball milled at 400r / min for 10h.

[0060] Step 5: the ball-milled material is dried and moved into a muffle furnace, and calcined at 1000℃ for 1h in an air atmosphere to obtain a regenerated lithium manganate powder.

[0061] The regenerated lithium manganate is assembled into a button-type half cell, and a charge-discharge test is performed to measure the charge-discharge performance at 1C rate.

[0062] Example 5

[0063] The embodiment 5 of the present application provides a normal-pressure recovery and regeneration method for waste lithium manganate positive electrode material, which is implemented through the following steps:

[0064] Step 1: the waste lithium manganate battery is soaked in a 5wt% sodium chloride aqueous solution and discharged to about 2V, and then cut and disassembled, step 2: after the positive plate is separated, it is cut into small pieces and soaked in dimethyl sulfoxide, the solid-liquid ratio is 1:10, the soaking time is 0.75h, the soaking temperature is 80℃, and the removed material is dried in an oven at 110℃ for 2h to obtain lithium manganate powder, the carbon content of which is 2.5wt%, and the total metal impurities are 120ppm.

[0065] Step 3: 5g of waste lithium manganate positive electrode powder is dispersed in 80mL of n-octanol solution and moved into a reactor, 15wt% of lithium hydroxide and 15wt% of oxalic acid based on the weight of the waste lithium manganate positive electrode powder are added, and fully stirred and mixed at a rotation speed of 300r / min, heated at 130℃ for 5h, naturally cooled after the reaction is completed, filtered, washed with ethanol, and dried to obtain a re-lithiated lithium manganate powder.

[0066] Step 4: The re-lithiated lithium manganate powder was mixed with 10wt% lithium nitrate, and then was moved into a stainless steel ball mill tank, and an appropriate amount of ethanol was added, and ball milling was carried out at 400r / min for 10h.

[0067] Step 5: After the ball-milled material was dried, it was moved into a muffle furnace and calcined at 800℃ for 2h in an air atmosphere to obtain the regenerated lithium manganate powder.

[0068] The regenerated lithium manganate was assembled into a button-type half cell, and charge-discharge test was carried out to measure the charge-discharge performance at 1C rate.

[0069] Comparative Example 1

[0070] In the present application, the collected lithium manganate black powder was directly tested by the following steps:

[0071] Step 1: The waste lithium manganate battery was soaked in a 5wt% sodium chloride aqueous solution and discharged to about 2V, and then cut and disassembled, and the positive plate was separated and cut into small pieces, and then soaked in N-methyl pyrrolidone with a solid-liquid ratio of 1:10, and the removed material was dried in an oven at 110℃ for 2h to obtain lithium manganate powder.

[0072] Step 2: The waste lithium manganate black powder was assembled into a button-type half cell, and charge-discharge test was carried out to measure the charge-discharge performance at 1C rate.

[0073] In the above examples, the selection of lithium source, carbon source, reducing agent, and reaction temperature and reaction time has a great influence on the specific capacity of the regenerated lithium manganate and the morphology of the material. Figure 2 The scanning electron microscope image of the waste lithium manganate material is shown, and it can be seen that the particle size of the waste material is greatly different, and the primary particles are broken, resulting in performance degradation of the material. Figure 3 The scanning electron microscope image of the regenerated lithium manganate material prepared in Example 1 is shown, and it can be seen that the regenerated lithium manganate material obtained after treatment by the normal pressure recovery and regeneration method of the waste lithium manganate positive material of the present application has complete particles, and the broken particles are repaired. Figure 4 The charge-discharge performance of the waste lithium manganate material and the regenerated lithium manganate material of Example 1 was compared, and it can be seen that by the normal pressure organic phase treatment of step S3 and the calcination of step S4 of the present application, in-situ lithium repair and in-situ lattice repair can be realized, and the specific capacity of the regenerated lithium manganate positive material obtained after treatment is greatly improved, reaching 122mAh g -1 , which has recovered to the level of normal lithium manganate material. The recovery of such specific capacity is due to the repair of damaged lithium manganate particles and lattice by the recovery and regeneration method of the present application, which realizes the recovery and regeneration of waste lithium manganate and improves the performance.

[0074] The above detailed description of the specific embodiments of the present application has been given to understand 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 is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for recycling and regenerating waste lithium manganese oxide cathode material under normal pressure, characterized in that, Includes the following steps: S1. Soak the waste lithium manganese oxide batteries in a sodium chloride aqueous solution, and disassemble them after discharge to obtain the waste lithium manganese oxide positive electrode sheet. S2. The waste lithium manganese 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 manganese oxide positive electrode powder. S3. Disperse the pretreated waste lithium manganese oxide cathode powder in a high-boiling-point organic solvent and transfer it into a reactor. Add the first lithium source and reducing agent, stir thoroughly, heat and stir the mixture, filter after reaction, wash with ethanol and dry to obtain relithiated lithium manganese oxide powder. The high-boiling-point organic solvent is selected from one or more of dimethyl ester (DBE), octyl acetate, n-octanol or ethylene glycol, and the amount added is 10-20 mL of organic solvent per gram of waste lithium manganese oxide. The reducing agent is selected from one of citric acid, formic acid, oxalic acid or ascorbic acid, and the mass added is 10-15 wt% of the mass of waste lithium manganese oxide powder. S4. The relithiated lithium manganese oxide powder is ball-milled with a second lithium source and ethanol and then dried. S5. The dried material is calcined in air to obtain recycled lithium manganese oxide powder.

2. The method for recycling and regenerating waste lithium manganese oxide cathode material under normal pressure 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.

3. The method for recycling and regenerating waste lithium manganese oxide cathode material under normal pressure 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 1:10-1:20 mg / mL, the soaking time is between 0.5-1h, and the soaking temperature is between 50-100℃; the total content of aluminum, copper, iron and other metal impurities in the waste lithium manganese oxide positive electrode powder is not higher than 1000ppm.

4. The method for recycling and regenerating waste lithium manganese oxide cathode material under normal pressure according to claim 1, characterized in that, In step S3, the first lithium source is one or more of lithium oxalate, lithium hydroxide, lithium carbonate, lithium nitrate, lithium acetate, lithium borohydride, and lithium aluminum hydride, and its added mass is 8-15 wt% of the mass of waste lithium manganese oxide powder.

5. The method for recycling and regenerating waste lithium manganese oxide cathode material under normal pressure according to claim 1, characterized in that, The heating temperature in step S3 is 130-180℃, the heating and stirring time is 1-5h, and the stirring speed is 100-400r / min.

6. The method for atmospheric pressure recycling and regeneration of waste lithium manganese oxide cathode material according to claim 1, characterized in that, In step S4, the second lithium source is one or more of lithium oxalate, lithium hydroxide, lithium carbonate, lithium nitrate, lithium acetate, lithium borohydride, and lithium aluminum hydride, and its added mass is 5-10 wt% of the mass of the relithiated lithium manganese oxide powder.

7. The method for recycling and regenerating waste lithium manganese oxide cathode material under normal pressure according to claim 1, characterized in that, The roasting temperature in step S5 is 700-1000℃, and the roasting time is 1-5h.

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