Post-treatment method for preparing battery-grade lithium carbonate from waste lithium batteries

Abstract

The invention relates to the technical field of lithium carbonate preparation, in particular to a post-treatment method for preparing battery-grade lithium carbonate from waste lithium batteries, which comprises the following steps: firstly preparing a lithium carbonate primary body from the waste lithium batteries, then adding a ball-milling agent accounting for 10-15% of the total amount of the lithium carbonate primary body into the lithium carbonate primary body, carrying out ball-milling treatment, and after ball-milling is finished, carrying out suction filtration and drying to obtain lithium carbonate powder; and carrying out sintering improvement treatment, and obtaining the battery-grade lithium carbonate after sintering is finished. According to the method for preparing the battery-grade lithium carbonate from the waste lithium batteries, the lithium carbonate initial body is matched with the ball milling agent for ball milling treatment, and then sintering improvement and optimization are performed, so that the obtained battery-grade lithium carbonate is excellent in discharge capacity stability effect under the high-rate condition and remarkable in capacity retention rate effect under the cycle condition.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium carbonate preparation, and particularly relates to a post-treatment method for preparing battery-grade lithium carbonate from waste lithium batteries. Background Art

[0002] As an energy storage device that can convert chemical energy and electrical energy into each other, lithium-ion batteries are the driving core of new energy vehicles. Due to their advantages such as good safety, good cycle performance, stable voltage, and good rate performance, lithium iron phosphate batteries have developed rapidly in the fields of power vehicles, energy storage, etc.; lithium iron phosphate batteries are widely used in our lives and have a high demand. Battery-grade lithium carbonate materials are required for the production of such lithium batteries.

[0003] Existing battery-grade lithium carbonate is recovered from waste lithium batteries. The recovery process is relatively existing, and the obtained battery-grade lithium carbonate has poor efficiency in battery production and utilization. For example, the battery-grade lithium carbonate obtained by the method of preparing battery-grade lithium carbonate from waste lithium iron phosphate electrode sheets in CN 109088120 B causes poor discharge capacity stability of the product in the battery under high-rate conditions, and low capacity retention rate under cycling conditions. The production of battery-grade lithium carbonate urgently needs further improvement. Summary of the Invention

[0004] Aiming at the defects of the existing technology, the purpose of the present invention is to provide a post-treatment method for preparing battery-grade lithium carbonate from waste lithium batteries to solve the problems raised in the above background art.

[0005] The present invention adopts the following technical solutions to solve the technical problems: The present invention provides a post-treatment method for preparing battery-grade lithium carbonate from waste lithium batteries, including the following steps: Step 1: First, make the waste lithium batteries into lithium carbonate precursors, and then add a ball milling agent accounting for 10-15% of the total amount of the lithium carbonate precursors to the lithium carbonate precursors for ball milling treatment; The ball milling agent is prepared by mixing and ball milling silicon carbide, zinc oxide whiskers doped with zirconium, and a conditioning compounding liquid; Step 2: After the ball milling is completed, perform suction filtration, drying, and then sintering improvement treatment. The sintering improvement treatment adopts a step-by-step and segmented thermal improvement treatment method. After the sintering is completed, battery-grade lithium carbonate is obtained.

[0006] Preferably, the ball milling speed of the ball milling treatment is 1500 r / min, and the ball milling is carried out for 1 h; the existing technology for making the waste lithium batteries into lithium carbonate precursors first refers to Example 1 in the method of preparing battery-grade lithium carbonate from waste lithium iron phosphate electrode sheets in CN 109088120 B.

[0007] Preferably, the preparation method of the ball milling agent is: S01: Heat the silicon carbide to 150 - 160 °C at a rate of 2 - 4 °C / min, hold for 10 min, then continue to heat to 270 - 280 °C at a rate of 1 - 3 °C / min, continue to hold for 20 min, and finally air-cool to room temperature; S02: Preparation of the conditioning compound solution: S021: Add 2 - 4 parts of lignocellulose, 1 - 2 parts of cerium oxide, and 2 - 3 parts of barium nitrate solution to 5 - 8 parts of hydrochloric acid dopamine solution, stir evenly to obtain the first conditioner; S022: Blend and sinter yttrium oxide, boron nitride, and carbon nanotubes according to the weight ratio (1 - 2):(3 - 5):2, sintering temperature 550 - 600 °C, sintering for 30 min, after sintering, obtain the second conditioner; Blend the second conditioner and the first conditioner according to the weight ratio 5:(7 - 9) and ultrasonically mix evenly to obtain the conditioning compound solution; S03: Blend and ball-mill 4 - 6 parts of the silicon carbide treated in S01, 2 - 5 parts of zirconium-doped zinc oxide whiskers, and 6 - 9 parts of the conditioning compound solution, ball-milling speed 1000 - 1500 r / min, ball-milling for 2 h, after ball-milling, obtain the ball-milling agent.

[0008] Preferably, the mass fraction of the barium nitrate solution is 2 - 5%; the mass fraction of the hydrochloric acid dopamine solution is 5 - 8%.

[0009] Preferably, the ultrasonic power for the ultrasonic mixing evenly is 400 - 450 W, ultrasonic for 20 - 30 min.

[0010] Preferably, the preparation method of the zirconium-doped zinc oxide whiskers is: Add 2 - 3 parts of zirconium oxide and 1 - 3 parts of nano-titanium dioxide to 5 - 8 parts of sodium dodecylbenzenesulfonate solution, then add 3 - 5 parts of zinc oxide whiskers and 1 - 2 parts of lanthanum chloride solution, blend and stir, and finally filter and dry to obtain the zirconium-doped zinc oxide whiskers.

[0011] Preferably, the mass fraction of the sodium dodecylbenzenesulfonate solution is 4 - 6%.

[0012] Preferably, the mass fraction of the lanthanum chloride solution is 3 - 5%.

[0013] Preferably, the stirring speed for the blend and stir is 550 - 750 r / min, stir for 20 - 30 min, and the stirring temperature is 58 °C.

[0014] Preferably, the specific operation steps of the sintering improvement treatment are: S11: First, perform heat treatment at a temperature of 300 - 350 °C for 1 h, then increase the temperature to 750 - 770 °C at a rate of 5 - 7 °C / min, and hold for 20 min; S12: Then, increase the temperature to 950 °C at a rate of 2 - 4 °C / min and continue to hold for 2 h; S13: Finally, decrease the temperature to 450 - 470 °C at a rate of 1 - 3 °C / min, hold for 1 h, and finally cool to room temperature at a rate of 8 - 10 °C / min.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, for the preparation of battery-grade lithium carbonate from waste lithium batteries, a lithium carbonate precursor is ball-milled with a ball-milling agent, and then sintered and improved and optimized. The obtained battery-grade lithium carbonate has excellent discharge capacity stability under high-rate conditions and remarkable capacity retention rate under cycling conditions; 2. The ball-milling agent uses silicon carbide. Heat it to 150 - 160 °C at a rate of 2 - 4 °C / min and hold for 10 min. Subsequently, continue to heat it to 270 - 280 °C at a rate of 1 - 3 °C / min and continue to hold for 20 min. The active efficiency of silicon carbide is improved and optimized by stepwise thermal improvement. At the same time, it is ball-milled by blending with a zinc oxide whisker doped with zirconium and a conditioning compounding solution. The first conditioner and the second conditioner in the conditioning compounding solution cooperate with each other for improvement. The first conditioner is made by blending wood cellulose, cerium oxide, barium nitrate solution, and dopamine hydrochloride solution. Wood cellulose provides a carbon source during sintering, and at the same time, it is coordinated with cerium oxide and barium nitrate solution to optimize the reinforcement and filling of cerium and barium elements in the system, further enhancing the performance coordination and performance stability of the system; 3. At the same time, the second conditioner is also coordinated. The yttrium oxide, boron nitride, and carbon nanotubes in the second conditioner are blended and sintered for improvement. Boron nitride has a flaky structure and interpenetrates in the system to reinforce the system. At the same time, carbon nanotubes have a high specific surface area and carry and cooperate with carbon nanotubes. At the same time, the yttrium element in yttrium oxide adjusts the system structure. The conditioning compounding solution made by coordinating the second conditioner to optimize the first conditioner can further optimize the discharge capacity stability and cycle capacity retention rate of the product in the system; 4. The zinc oxide whisker doped with zirconium uses zirconium oxide, nano-titanium dioxide, and zinc oxide whiskers. Through the whisker structure, it cooperates with raw materials such as zirconium oxide to enhance the interfacial property of the system in the system. The blending of zirconium oxide and nano-titanium dioxide is optimized and adjusted through the whisker structure. At the same time, it is blended and coordinated through the blending of sodium dodecylbenzenesulfonate solution and lanthanum chloride solution. Through the activity improvement of the sodium dodecylbenzenesulfonate solution and the coordination and synergy between rare earth lanthanum chloride raw materials, the zinc oxide whisker doped with zirconium obtained further enhances the performance effect of the product system in the system and optimizes the performance stability of the product; 5. For the sintering improvement treatment, perform heat treatment at a temperature of 300 - 350 °C for 1 h, then raise the temperature at a rate of 5 - 7 °C / min to 750 - 770 °C and hold for 20 min; then raise the temperature at a rate of 2 - 4 °C / min to 950 °C and continue to hold for 2 h; finally, lower the temperature at a rate of 1 - 3 °C / min to 450 - 470 °C and hold for 1 h, and finally cool to room temperature at a rate of 8 - 10 °C / min. Through step-by-step and segmented continuous heat improvement, as well as heating, reheating, and cooling, the lithium carbonate can be sintered more fully, the product system structure can be made more dense, and the coordination between product raw materials can be further adjusted, so that the product performance is significantly improved. Detailed implementation mode

[0016] The following combines specific embodiments to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0017] A post-treatment method for preparing battery-grade lithium carbonate from waste lithium batteries in this embodiment includes the following steps: According to the prior art, first make the waste lithium battery into a lithium carbonate precursor, then add a ball milling agent accounting for 10 - 15% of the total amount of the lithium carbonate precursor to the lithium carbonate precursor for ball milling treatment. After the ball milling is completed, perform suction filtration and drying, and then perform sintering improvement treatment. After the sintering is completed, obtain the battery-grade lithium carbonate of the present invention.

[0018] The ball milling speed of the ball milling treatment in this embodiment is 1500 r / min, and the ball milling is carried out for 1 h.

[0019] The preparation method of the ball milling agent in this embodiment is as follows: S01: First raise the temperature of silicon carbide at a rate of 2 - 4 °C / min to 150 - 160 °C, hold for 10 min, then continue to raise the temperature at a rate of 1 - 3 °C / min to 270 - 280 °C, and continue to hold for 20 min, and finally air-cool to room temperature; S02: Preparation of the conditioning complex solution: S021: Add 2 - 4 parts of wood cellulose, 1 - 2 parts of cerium oxide, and 2 - 3 parts of barium nitrate solution to 5 - 8 parts of hydrochloric acid dopamine solution, and stir evenly to obtain the first conditioner; S022: Blend and sinter yttrium oxide, boron nitride, and carbon nanotubes according to the weight ratio of (1 - 2):(3 - 5):2. The sintering temperature is 550 - 600 °C, and the sintering is carried out for 30 min. After the sintering is completed, obtain the second conditioner; Blend the second conditioner and the first conditioner according to the weight ratio of 5:(7 - 9) and ultrasonically mix them evenly to obtain the conditioning complex solution; S03: 4 - 6 parts of silicon carbide treated by S01, 2 - 5 parts of zinc oxide whiskers doped with zirconium, and 6 - 9 parts of conditioning compounding liquid are blended and ball - milled. The ball - mill rotation speed is 1000 - 1500 r / min, and ball - milling is carried out for 2 h. After ball - milling is completed, a ball - milling agent is obtained.

[0020] In this embodiment, the mass fraction of the barium nitrate solution is 2 - 5%; the mass fraction of the dopamine hydrochloride solution is 5 - 8%.

[0021] In this embodiment, the ultrasonic power for the blended ultrasonic uniformity is 400 - 450 W, and ultrasonic treatment is carried out for 20 - 30 min.

[0022] The preparation method of the zinc oxide whiskers doped with zirconium in this embodiment is as follows: 2 - 3 parts of zirconium oxide and 1 - 3 parts of nano - titanium dioxide are added to 5 - 8 parts of sodium dodecylbenzenesulfonate solution. Subsequently, 3 - 5 parts of zinc oxide whiskers and 1 - 2 parts of lanthanum chloride solution are added, and they are blended and stirred. Finally, filtration and drying are carried out to obtain zinc oxide whiskers doped with zirconium.

[0023] In this embodiment, the mass fraction of the sodium dodecylbenzenesulfonate solution is 4 - 6%.

[0024] In this embodiment, the mass fraction of the lanthanum chloride solution is 3 - 5%.

[0025] In this embodiment, the stirring speed for the blended stirring treatment is 550 - 750 r / min, stirring is carried out for 20 - 30 min, and the stirring temperature is 58 °C.

[0026] The specific operation steps of the sintering improvement treatment in this embodiment are as follows: S11: First, heat - treat at a temperature of 300 - 350 °C for 1 h, then increase the temperature at a rate of 5 - 7 °C / min to 750 - 770 °C, and keep the temperature for 20 min; S12: Then increase the temperature at a rate of 2 - 4 °C / min to 950 °C and continue to keep the temperature for 2 h; S13: Finally, decrease the temperature at a rate of 1 - 3 °C / min to 450 - 470 °C, keep the temperature for 1 h, and finally cool to room temperature at a rate of 8 - 10 °C / min.

[0027] Example 1 A post - treatment method for preparing battery - grade lithium carbonate from waste lithium batteries in this embodiment includes the following steps: According to the existing technology, waste lithium batteries are first made into lithium carbonate precursors, and then a ball - milling agent accounting for 10% of the total amount of lithium carbonate precursors is added to the lithium carbonate precursors for ball - milling treatment. After ball - milling is completed, filtration and drying are carried out, and then sintering improvement treatment is carried out. After sintering is completed, the battery - grade lithium carbonate of the present invention is obtained.

[0028] The ball milling speed in the ball milling treatment of this embodiment is 1500 r / min, and the ball milling is carried out for 1 h.

[0029] The preparation method of the ball milling agent in this embodiment is as follows: S01: First, heat the silicon carbide at a rate of 2 °C / min to 150 °C, keep it warm for 10 min, then continue to heat it at a rate of 1 °C / min to 270 °C, and continue to keep it warm for 20 min. Finally, air-cool it to room temperature; S02: Preparation of the conditioning compound solution: S021: Add 2 parts of lignocellulose, 1 part of cerium oxide and 2 parts of barium nitrate solution to 5 parts of hydrochloric acid dopamine solution, stir evenly to obtain the first conditioner; S022: Blend and sinter yttrium oxide, boron nitride and carbon nanotubes according to the weight ratio of 1:3:2. The sintering temperature is 550 °C, and the sintering is carried out for 30 min. After the sintering is completed, obtain the second conditioner; Blend the second conditioner and the first conditioner according to the weight ratio of 5:7 and ultrasonically mix them evenly to obtain the conditioning compound solution; Carry out a ball milling treatment by blending 4 parts of the silicon carbide treated in S01, 2 parts of the zinc oxide whisker doped with zirconium and 6 parts of the conditioning compound solution. The ball milling speed is 1000 r / min, and the ball milling is carried out for 2 h. After the ball milling is completed, obtain the ball milling agent.

[0030] The mass fraction of the barium nitrate solution in this embodiment is 2%; the mass fraction of the hydrochloric acid dopamine solution is 5%.

[0031] The ultrasonic power for ultrasonically mixing evenly in this embodiment is 400 W, and the ultrasonic treatment is carried out for 20 min.

[0032] The preparation method of the zinc oxide whisker doped with zirconium in this embodiment is as follows: Add 2 parts of zirconium oxide and 1 part of nano-titanium dioxide to 5 parts of sodium dodecylbenzenesulfonate solution, then add 3 parts of zinc oxide whiskers and 1 part of lanthanum chloride solution, carry out a blending and stirring treatment, and finally carry out suction filtration and drying to obtain the zinc oxide whisker doped with zirconium.

[0033] The mass fraction of the sodium dodecylbenzenesulfonate solution in this embodiment is 4%.

[0034] The mass fraction of the lanthanum chloride solution in this embodiment is 3%.

[0035] The stirring speed in the blending and stirring treatment in this embodiment is 550 r / min, the stirring is carried out for 2 min, and the stirring temperature is 58 °C.

[0036] The specific operation steps of the sintering improvement treatment in this embodiment are as follows: S11: First, carry out a heat treatment at a temperature of 300 °C for 1 h, then heat it at a rate of 5 °C / min to 750 °C, and keep it warm for 20 min; S12: Then, heat it up to 950 °C at a rate of 2 °C / min and continue to hold for 2 h. S13: Finally, cool it down to 450 °C at a rate of 1 °C / min, hold for 1 h, and then cool it to room temperature at a rate of 8 °C / min.

[0037] Example 2 A post-treatment method for preparing battery-grade lithium carbonate from waste lithium batteries in this example includes the following steps: According to the existing technology, first make the waste lithium batteries into lithium carbonate precursors, then add a ball-milling agent accounting for 15% of the total amount of the lithium carbonate precursors to the lithium carbonate precursors for ball-milling treatment. After the ball-milling is completed, perform suction filtration and drying, and then perform sintering improvement treatment. After the sintering is completed, obtain the battery-grade lithium carbonate of the present invention.

[0038] In this example, the ball-milling speed for the ball-milling treatment is 1500 r / min, and the ball-milling time is 1 h.

[0039] The preparation method of the ball-milling agent in this example is as follows: S01: Heat silicon carbide to 160 °C at a rate of 4 °C / min, hold for 10 min, then continue to heat it to 280 °C at a rate of 3 °C / min, continue to hold for 20 min, and finally air-cool it to room temperature. Preparation of the conditioning complex solution: S021: Add 4 parts of lignocellulose, 2 parts of cerium oxide, and 3 parts of barium nitrate solution to 8 parts of hydrochloric acid dopamine solution, stir evenly to obtain the first conditioner. S022: Blend yttrium oxide, boron nitride, and carbon nanotubes according to a weight ratio of 2:5:2 for sintering treatment. The sintering temperature is 600 °C, and the sintering time is 30 min. After the sintering is completed, obtain the second conditioner. Blend the second conditioner and the first conditioner according to a weight ratio of 5:9 and ultrasonically mix them evenly to obtain the conditioning complex solution. S03: Blend 6 parts of silicon carbide treated in S01, 5 parts of zinc oxide whisker doped with zirconium, and 9 parts of the conditioning complex solution for ball-milling treatment. The ball-milling speed is 1500 r / min, and the ball-milling time is 2 h. After the ball-milling is completed, obtain the ball-milling agent.

[0040] In this example, the mass fraction of the barium nitrate solution is 5%; the mass fraction of the hydrochloric acid dopamine solution is 8%.

[0041] In this example, the ultrasonic power for the ultrasonic mixing is 450 W, and the ultrasonic time is 30 min.

[0042] The preparation method of the zinc oxide whisker doped with zirconium in this example is as follows: Add 3 parts of zirconia and 3 parts of nano-titanium dioxide into 8 parts of sodium dodecylbenzenesulfonate solution, then add 5 parts of zinc oxide whiskers and 2 parts of lanthanum chloride solution, conduct a blending and stirring treatment, and finally carry out suction filtration and drying to obtain a zinc oxide whisker body doped with zirconium.

[0043] In this example, the mass fraction of the sodium dodecylbenzenesulfonate solution is 6%.

[0044] In this example, the mass fraction of the lanthanum chloride solution is 5%.

[0045] In this example, the stirring speed of the blending and stirring treatment is 750 r / min, stir for 30 min, and the stirring temperature is 58 °C.

[0046] The specific operation steps of the sintering improvement treatment in this example are as follows: S11: First, conduct heat treatment at a temperature of 350 °C for 1 h, then increase the temperature to 770 °C at a rate of 7 °C / min, and keep the temperature for 20 min; S12: Then increase the temperature to 950 °C at a rate of 4 °C / min and continue to keep the temperature for 2 h; S13: Finally, decrease the temperature to 470 °C at a rate of 3 °C / min, keep the temperature for 1 h, and finally cool to room temperature at a rate of 10 °C / min, and that's it.

[0047] Example 3 A post-treatment method for preparing battery-grade lithium carbonate from waste lithium batteries in this example includes the following steps: According to the existing technology, first make the waste lithium battery into a lithium carbonate precursor, then add a ball milling agent accounting for 12.5% of the total amount of the lithium carbonate precursor to the lithium carbonate precursor for ball milling treatment. After the ball milling is completed, conduct suction filtration and drying, and then carry out sintering improvement treatment. After the sintering is completed, obtain the battery-grade lithium carbonate of the present invention.

[0048] In this example, the ball milling speed of the ball milling treatment is 1500 r / min, and the ball milling time is 1 h.

[0049] The preparation method of the ball milling agent in this example is as follows: S01: First, heat the silicon carbide to 155 °C at a rate of 3 °C / min, keep the temperature for 10 min, then continue to heat to 275 °C at a rate of 2 °C / min, and continue to keep the temperature for 20 min, and finally air-cool to room temperature; S02: Preparation of the conditioning and re-conditioning liquid: S021: Add 3 parts of wood cellulose, 1.5 parts of cerium oxide, and 2.5 parts of barium nitrate solution into 6.5 parts of hydrochloric acid dopamine solution, stir evenly to obtain the first conditioner; S022: Blend and sinter yttrium oxide, boron nitride, and carbon nanotubes according to a weight ratio of 1.5:4:2. The sintering temperature is 575 °C, sinter for 30 min. After the sintering is completed, obtain the second conditioner; Mix the second modifier and the first modifier in a weight ratio of 5:8 and ultrasonically homogenize them to obtain a compound modifier solution. S03: Blend 5 parts of SiC treated with S01, 3.5 parts of zinc oxide whiskers doped with zirconium, and 7.5 parts of the compound modifier solution, and perform ball milling treatment. The ball milling speed is 1250 r / min, and the ball milling time is 2 h. After the ball milling is completed, a ball milling agent is obtained.

[0050] In this example, the mass fraction of the barium nitrate solution is 3.5%; the mass fraction of the dopamine hydrochloride solution is 6.5%.

[0051] In this example, the ultrasonic power for ultrasonic homogenization is 425 W, and the ultrasonic treatment time is 25 min.

[0052] The preparation method of the zinc oxide whiskers doped with zirconium in this example is as follows: Add 2.5 parts of zirconium oxide and 2 parts of nano-titanium dioxide into 6.5 parts of sodium dodecylbenzenesulfonate solution. Then add 4 parts of zinc oxide whiskers and 1.5 parts of lanthanum chloride solution, and perform a blending and stirring treatment. Finally, perform suction filtration and drying to obtain zinc oxide whiskers doped with zirconium.

[0053] In this example, the mass fraction of the sodium dodecylbenzenesulfonate solution is 5%.

[0054] In this example, the mass fraction of the lanthanum chloride solution is 4%.

[0055] In this example, the stirring speed for the blending and stirring treatment is 600 r / min, the stirring time is 25 min, and the stirring temperature is 58 °C.

[0056] The specific operation steps of the sintering improvement treatment in this example are as follows: S11: First, perform heat treatment at a temperature of 325 °C for 1 h, then increase the temperature to 760 °C at a rate of 6 °C / min, and keep it warm for 20 min; S12: Then increase the temperature to 950 °C at a rate of 3 °C / min and continue to keep it warm for 2 h; S13: Finally, decrease the temperature to 460 °C at a rate of 2 °C / min, keep it warm for 1 h, and finally cool it to room temperature at a rate of 9 °C / min.

[0057] Comparative Example 1 The difference from Example 3 is that the ball milling agent is not added.

[0058] Comparative Example 2 The difference from Example 3 is that SiC treated with S01 is not added to the ball milling agent.

[0059] Comparative Example 3 The difference from Example 3 is that zinc oxide whiskers doped with zirconium are not added to the ball milling agent.

[0060] Comparative Example 4 Different from Example 3, the conditioning complex solution was not added to the ball milling agent.

[0061] Comparative Example 5 Different from Example 3, the first conditioning agent was not added during the preparation of the conditioning complex solution.

[0062] Comparative Example 6 Different from Example 3, wood cellulose and cerium oxide were not added to the first conditioning agent.

[0063] Comparative Example 7 Different from Example 3, the barium nitrate solution was not added to the first conditioning agent, and the hydrochloric acid dopamine solution was replaced with water.

[0064] Comparative Example 8 Different from Example 3, the second conditioning agent was not added during the preparation of the conditioning complex solution.

[0065] Comparative Example 9 Different from Example 3, yttrium oxide and boron nitride were not added to the second conditioning agent.

[0066] Comparative Example 10 Different from Example 3, carbon nanotubes were not added to the second conditioning agent.

[0067] Comparative Example 11 Different from Example 3, the sintering improvement treatment was not adopted.

[0068] Comparative Example 12 Different from Example 3, the S11 step was not adopted during the preparation of the sintering improvement treatment, and the temperature was directly raised to 950 °C at a rate of 3 °C / min.

[0069] Comparative Example 13 Different from Example 3, the S13 step was not adopted during the preparation of the sintering improvement treatment, and the temperature at 950 °C was directly air-cooled to room temperature.

[0070] According to the prior art, the products of Examples 1 to 3 and Comparative Examples 1 to 13 were used as additives to make positive electrode sheets, and button batteries were assembled for chemical performance testing. The performance test results are as follows:

[0071] It can be seen from Comparative Examples 1 to 12 and Examples 1 to 3; The product of Example 3 has excellent discharge capacity and discharge capacity retention rate. At the same time, under high-rate conditions, the discharge capacity stability effect of the product is remarkable, and under multiple cycle conditions, the capacity retention rate effect is excellent; It can be seen from Comparative Examples 1 to 12 and Example 3 that in the preparation of the product process, the performance of the product deteriorates significantly without adding a ball milling agent. When silicon carbide treated with S01 is not added to the ball milling agent, zinc oxide whiskers doped with zirconium are not added to the ball milling agent, and the conditioning compounding liquid is not added to the ball milling agent, the performance of the product shows a deteriorating trend to varying degrees. At the same time, when zinc oxide whiskers doped with zirconium are not added, the deteriorating trend of the product performance is more obvious; When the first conditioning agent is not added in the preparation of the conditioning compounding liquid, lignocellulose and cerium oxide are not added to the first conditioning agent, barium nitrate solution is not added to the first conditioning agent, and hydrochloric acid dopamine solution is replaced with water, and the second conditioning agent is not added in the preparation of the conditioning compounding liquid, yttrium oxide and boron nitride are not added to the second conditioning agent, and carbon nanotubes are not added to the second conditioning agent, the performance of the product shows a deteriorating trend to varying degrees. The performance effect of the product is the most significant when the conditioning compounding liquid is prepared with the first conditioning agent and the second conditioning agent in the specific ratio obtained by the method of the present invention; In addition, the performance effect of the product is the most significant when the ball milling agent is made of zinc oxide whiskers doped with zirconium, the conditioning compounding liquid and silicon carbide treated with S01 obtained by the method of the present invention. Using other methods instead is not as obvious as the effect of the present invention; At the same time, when the sintering improvement treatment is not adopted in the product process, the S11 step is not adopted in the preparation of the sintering improvement treatment, and the temperature is directly raised to 950 °C at a rate of 3 °C / min, and the S13 step is not adopted in the preparation of the sintering improvement treatment, and the temperature of 950 °C is directly air-cooled to room temperature, the performance of the product shows a deteriorating trend; only when the sintering improvement treatment obtained by the specific process of the present invention is adopted, the performance effect of the product is the most significant.

[0072] Based on the fact that zinc oxide whiskers doped with zirconium have a great influence on the performance of the product, further research is carried out on this: Experimental Example 1 The only difference from Example 3 is that zirconium oxide is not added in the preparation of zinc oxide whiskers doped with zirconium.

[0073] Experimental Example 2 The only difference from Example 3 is that nano-titanium dioxide is not added in the preparation of zinc oxide whiskers doped with zirconium.

[0074] Experimental Example 3 The only difference from Example 3 is that zinc oxide whiskers are not added in the preparation of zinc oxide whiskers doped with zirconium.

[0075] Experimental Example 4 The only difference from Example 3 is that lanthanum chloride solution is not added in the preparation of zinc oxide whiskers doped with zirconium.

[0076] Experimental Example 5 The only difference from Example 3 is that the mass fraction of the lanthanum chloride solution is 7%.

[0077] By exploring the specific preparation method of zirconium-doped zinc oxide whiskers and its influence on the chemical properties of button batteries, the test results are as follows:

[0078] It can be seen from Experimental Examples 1-5 that when zinc oxide whiskers are not added in the preparation of zirconium-doped zinc oxide whiskers, the performance change trend of the product is relatively large. At the same time, when zirconium oxide, nano-titanium dioxide, and lanthanum chloride solution are not added in the preparation of zirconium-doped zinc oxide whiskers, the performance of the product shows a deteriorating trend. Also, when the mass fraction of the lanthanum chloride solution is 7%, the performance of the product also shows a deteriorating trend. For zirconium-doped zinc oxide whiskers obtained by different methods, the performance of the product shows a deteriorating trend. Only the zirconium-doped zinc oxide whiskers prepared with the specific raw materials of the present invention have the most significant performance effect, and the specific mass fraction of the lanthanum chloride solution also has a changing trend on the performance of the product. When the mass fraction within the scope of the present invention is used, the performance effect is the best.

[0079] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be encompassed within the present invention.

[0080] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A post-processing method for preparing battery-grade lithium carbonate from waste lithium batteries, characterized in that: The following steps are involved: Step 1: First, the waste lithium battery is made into a lithium carbonate primary body, and then a ball milling agent of 10-15% of the total amount of the lithium carbonate primary body is added to the lithium carbonate primary body for ball milling treatment; The ball mill is made by mixing silicon carbide, zirconium-doped zinc oxide whiskers and a conditioning compound liquid through ball milling. Step 2: After the ball milling is completed, the product is filtered, dried, and then sintered for improvement. The sintering improvement process adopts a step-by-step and segmented thermal improvement treatment method. After the sintering is completed, battery-grade lithium carbonate is obtained.

2. A post-processing method for preparing battery-grade lithium carbonate from waste lithium batteries according to claim 1, characterized in that: The ball milling speed of the ball milling treatment is 1200-1500 r / min, and the ball milling is performed for 1 hour.

3. A post-processing method for preparing battery-grade lithium carbonate from waste lithium batteries according to claim 1, characterized in that: The specific preparation method of the ball mill is: S01: Heat the silicon carbide to 150-160°C at a rate of 2-4°C / min, keep it warm for 10 minutes, then continue to heat it to 270-280°C at a rate of 1-3°C / min, keep it warm for 20 minutes, and finally air-cool it to room temperature; S02: Preparation of compounding solution: S021: adding 2-4 parts of lignocellulose, 1-2 parts of cerium oxide and 2-3 parts of barium nitrate solution to 5-8 parts of dopamine hydrochloride solution, stirring evenly, to obtain a first conditioning agent; S022: sintering yttrium oxide, boron nitride and carbon nanotubes in a weight ratio of (1-2): (3-5): 2 at a sintering temperature of 550-600°C for 30 minutes to obtain a second conditioning agent; The second conditioning agent and the first conditioning agent are uniformly blended by ultrasonic mixing in a weight ratio of 5:(7-9) to obtain a conditioning compound liquid; S03: 4-6 parts of silicon carbide treated with S01, 2-5 parts of zinc oxide whiskers doped with zirconium and 6-9 parts of the conditioning compound liquid are mixed and ball-milled at a ball-milling speed of 1000-1500 r / min for 2 hours to obtain a ball milling agent.

4. A post-processing method for preparing battery-grade lithium carbonate from waste lithium batteries according to claim 3, characterized in that: The mass fraction of the barium nitrate solution is 2-5%; the mass fraction of the dopamine hydrochloride solution is 5-8%.

5. A post-processing method for preparing battery-grade lithium carbonate from waste lithium batteries according to claim 3, characterized in that: The ultrasonic power of the blending is 400-450W, and the ultrasonication is carried out for 20-30 minutes.

6. A post-processing method for preparing battery-grade lithium carbonate from waste lithium batteries according to claim 3, characterized in that: The preparation method of the zirconium-doped zinc oxide whisker body is: 2-3 parts of zirconium oxide and 1-3 parts of nano-titanium dioxide are added to 5-8 parts of sodium dodecylbenzene sulfonate solution, followed by adding 3-5 parts of zinc oxide whiskers and 1-2 parts of lanthanum chloride solution, blending and stirring, and finally filtering and drying to obtain zirconium-doped zinc oxide whiskers.

7. The post-processing method for preparing battery-grade lithium carbonate from waste lithium batteries according to claim 6, characterized in that: The mass fraction of the sodium dodecylbenzene sulfonate solution is 4-6%.

8. The post-processing method for preparing battery-grade lithium carbonate from waste lithium batteries according to claim 6, characterized in that: The mass fraction of the lanthanum chloride solution is 3-5%.

9. The post-processing method for preparing battery-grade lithium carbonate from waste lithium batteries according to claim 6, characterized in that: The mixing and stirring process is performed at a stirring speed of 550-750 r / min, stirring for 20-30 min, and a stirring temperature of 58° C.

10. The post-processing method for preparing battery-grade lithium carbonate from waste lithium batteries according to claim 1, characterized in that: The specific operation steps of the sintering improvement treatment are: S11: first heat treat at 300-350°C for 1h, then heat to 750-770°C at a rate of 5-7°C / min, and keep at this temperature for 20min; S12: Then, the temperature is raised to 950°C at a rate of 2-4°C / min and kept at this temperature for 2h; S13: Finally, cool down to 450~470℃ at a rate of 1~3℃ / min, keep warm for 1h, and finally cool to room temperature at a rate of 8~10℃ / min.

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