A uniform and efficient wet method for repairing lithium cobalt oxide and its application

Abstract

The invention relates to the technical field of H01M10 / 54, and specifically to a method for uniform and efficient wet-process repair of lithium cobalt oxide and an application thereof. The powder on the positive electrode sheet of the recycled waste lithium cobalt oxide battery is separated from the foil material, and a primary powder is obtained after a primary screening to remove magnetism. The primary powder is mixed with an additive to obtain a secondary mixed material. The secondary mixed material is filtered, dried, crushed, and then subjected to high-temperature sintering to obtain a tertiary powder. The tertiary powder is crushed, subjected to a secondary screening to remove magnetism, washed with water, and then dried. The method is simple, has less consumables, high recovery efficiency, is safe and environmentally friendly, and the recovered and repaired lithium cobalt oxide has excellent electrochemical properties and processing properties.

Description

Technical Field

[0001] The invention relates to the technical field of H01M10 / 54, and in particular to a method for uniformly and efficiently repairing lithium cobalt oxide by wet method and application thereof. Background Art

[0002] As the population increases, people have higher requirements for chemical energy, namely high quality, long life and low pollution. As a "green energy", lithium-ion secondary batteries also have a certain lifespan, generally about 3 years. Lithium-ion secondary batteries will become an important part of solid waste in the future. How to properly dispose of discarded lithium-ion secondary batteries will be a major problem facing people.

[0003] In the prior art, waste lithium-ion batteries are generally treated by pyrolysis and wet methods. Wet recovery is a relatively mature method, which uses strong acid to dissolve the electrode material, and then uses precipitation separation or solvent extraction to separate and recover the metal elements contained in the leachate. The process of recovering cobalt from waste lithium-ion batteries is generally crushing, physical separation, acid leaching, and then chemical precipitation to generate cobalt hydroxide, cobalt oxalate, and cobalt sulfate. For example, a Chinese patent application (authorization announcement number CN110668506B) discloses a method for recycling and regenerating lithium cobalt oxide from waste lithium-ion batteries. Specifically, the recovered positive electrode active material is mixed with a low co-solvent containing oxalic acid to obtain cobalt oxalate, and then precipitated, dried, and roasted to complete the recovery. However, its process consumables are large, the reagent utilization rate is low, the recovery rate is low, and a large amount of waste liquid is generated. Summary of the invention

[0004] In order to solve the problems of complicated and cumbersome existing wet process, large reagent consumption, high recovery and repair cost, low recovery rate and large amount of waste liquid which is not conducive to environmental protection, the present invention discloses a uniform and efficient wet process for repairing lithium cobalt oxide. The method is simple, has few consumables, high recovery efficiency, safety and environmental protection, and the recovered and repaired lithium cobalt oxide has excellent electrochemical properties and processing properties.

[0005] The invention provides a uniform and efficient wet method for repairing lithium cobalt oxide, comprising the steps of separating powder and foil on a positive electrode sheet of a recycled waste lithium cobalt oxide battery, removing magnetism through a primary screening to obtain a primary powder, mixing the primary powder with an additive to obtain a secondary mixture, filtering, drying, crushing the secondary mixture, and then sintering at a high temperature to obtain a tertiary powder, and crushing the tertiary powder, removing magnetism through a secondary screening, washing with water, and then drying.

[0006] As a preferred technical solution, the separation temperature is 180-320°C and the separation time is 1-8h. The present invention processes the recycled lithium cobalt oxide pole piece at 180-320°C to achieve simple separation of powder and foil, without the need for additional reagent consumption, reducing the amount of waste liquid generated in the entire process and reducing pollution to the environment.

[0007] As a preferred technical solution, the first-level screen and the second-level screen are both ultrasonic vibration screens, and the demagnetization instrument is an electromagnetic iron remover.

[0008] As a preferred technical solution, the particle size of the primary powder is 100-200 mesh.

[0009] As a preferred technical solution, the additive is an inorganic salt solution with a concentration of 1-5 mol / L. Preferably, the inorganic salt solution is at least one of K inorganic salt solution, Mg inorganic salt solution, P inorganic salt solution, Ca inorganic salt solution, Zn inorganic salt solution, Cr inorganic salt solution, and Na inorganic salt solution;

[0010] As a preferred technical solution, the solid content of the secondary mixture is 10-50wt%.

[0011] As a preferred technical solution, the drying conditions are: temperature of 100-150°C and drying time of 3-5h.

[0012] As a preferred technical solution, the high temperature sintering temperature is 400-1100°C, and the high temperature sintering time is 5-20h. Preferably, the high temperature sintering adopts uniform heating and uniform cooling; preferably, the uniform heating and uniform cooling rate is 5-15°C / min.

[0013] As a preferred technical solution, 100-20000 ppm of lithium source material is added during the high temperature sintering; preferably, the lithium source material is selected from at least one of lithium carbonate, lithium hydroxide, lithium ethoxide, lithium methanol, lithium isopropoxide and lithium butoxide.

[0014] The present invention treats the primary powder with additives, especially with an inorganic salt aqueous solution with a concentration of 1-5 mol / L, and then controls the program to increase the temperature to 400-1100° C. for high-temperature sintering, so that the repaired lithium cobalt oxide positive electrode material has an initial discharge specific capacity of 177.2 mAh / g, which is equivalent to that of lithium cobalt oxide positive electrode materials at the same level, and can be effectively recycled subsequently.

[0015] As a preferred technical solution, the mesh size of the secondary sieve is 300-400 meshes.

[0016] As a preferred technical solution, the mass ratio of the tertiary powder to water during the water washing is (0.1-0.4):1.

[0017] On the other hand, the present invention provides an application of a uniform and efficient wet method for repairing lithium cobalt oxide, which is applied to the repair of lithium cobalt oxide positive electrode materials in waste batteries.

[0018] Beneficial effects:

[0019] 1. The present invention discloses a uniform and efficient wet-process method for repairing lithium cobalt oxide, which solves the problems of the existing wet process being complicated and cumbersome, large reagent consumption, high recovery and repair cost, low recovery rate, and a large amount of waste liquid that is not conducive to environmental protection.

[0020] 2. The method provided by the present invention is simple, requires less consumables, has high recovery efficiency, is safe and environmentally friendly, and the recovered and repaired lithium cobalt oxide has excellent electrochemical properties and processing properties.

[0021] 3. The present invention processes the recycled lithium cobalt oxide pole pieces at 180-320°C to achieve simple separation of powder and foil, without the need for additional reagent consumption, thereby reducing the amount of waste liquid generated during the entire process and reducing pollution to the environment.

[0022] 4. The present invention treats the primary powder with additives, especially with an inorganic salt aqueous solution with a concentration of 1-5 mol / L, and then controls the program to increase the temperature to 400-1100°C for high-temperature sintering, so that the repaired lithium cobalt oxide positive electrode material has an initial discharge specific capacity of 177.2 mAh / g, which is equivalent to that of lithium cobalt oxide positive electrode materials at the same level, and can be effectively recycled subsequently. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a scanning electron microscope photograph of the repaired lithium cobalt oxide positive electrode material of Example 1 of the present invention.

[0024] Figure 2 This is a scanning electron microscope photograph of the lithium cobalt oxide positive electrode material after repair in comparative example 1 of the present invention.

[0025] Figure 3 It is a comparison diagram of the charge and discharge curves of the lithium cobalt oxide positive electrode material after repair in Example 1 of the present invention and in Comparative Example 1. DETAILED DESCRIPTION

[0026] Example 1

[0027] Embodiment 1 of the present invention provides a uniform and efficient method for wet-process repairing lithium cobalt oxide, wherein the powder on the positive electrode sheet of the recycled waste lithium cobalt oxide battery is separated from the foil, and a first-level powder is obtained after a first-level screening to remove magnetism, and the first-level powder is mixed with an additive to obtain a second-level mixture, and the second-level mixture is filtered, dried, crushed, and then sintered at a high temperature to obtain a third-level powder, and the third-level powder is crushed, screened through a second level to remove magnetism, washed with water, and then dried.

[0028] The recycled waste lithium cobalt oxide batteries come from battery factories.

[0029] The separation temperature is 250° C. and the separation time is 3 h.

[0030] The first-stage screen and the second-stage screen are both ultrasonic vibrating screens, and the demagnetizing instrument is an electromagnetic iron remover.

[0031] The particle size of the primary powder is 100 meshes.

[0032] The additive is an inorganic salt aqueous solution with a concentration of 1.3 mol / L. The inorganic salt aqueous solution is a Na2CO3 aqueous solution.

[0033] The solid content of the secondary mixture is 30wt%.

[0034] The drying conditions are: temperature of 120° C. and drying time of 5 h.

[0035] The high temperature sintering temperature is 980°C, the high temperature sintering time is 10 hours, and the high temperature sintering adopts uniform heating and uniform cooling; the rate of uniform heating and uniform cooling is 10°C / min.

[0036] The amount of high-temperature sintered lithium source added is 5000ppm of Li element; the lithium source material is lithium carbonate.

[0037] The mesh size of the secondary sieve is 325 meshes.

[0038] During the water washing, the mass ratio of the tertiary powder to water is 0.3:1.

[0039] On the other hand, Example 1 of the present invention provides an application of a uniform and efficient wet method for repairing lithium cobalt oxide, which is applied to the repair of lithium cobalt oxide positive electrode materials in waste batteries.

[0040] Comparative Example 1

[0041] Comparative Example 1 of the present invention provides a uniform and efficient wet method for repairing lithium cobalt oxide, wherein the powder on the positive electrode sheet of the recycled waste lithium cobalt oxide battery is separated from the foil, and the first-level powder is obtained after a first-level screening to remove magnetism, and the first-level powder is sintered at a high temperature to obtain a third-level powder, and the third-level powder is crushed, screened through a second level to remove magnetism, washed with water, and then dried.

[0042] The recycled waste lithium cobalt oxide batteries come from battery factories.

[0043] The separation temperature is 250° C. and the separation time is 3 h.

[0044] The first-stage screen and the second-stage screen are both ultrasonic vibrating screens, and the demagnetizing instrument is an electromagnetic iron remover.

[0045] The particle size of the primary powder is 100 meshes.

[0046] The drying conditions are: temperature 120°C, drying time 5h

[0047] The high temperature sintering temperature is 980°C, the high temperature sintering time is 10 hours, and the high temperature sintering adopts uniform heating and uniform cooling; the rate of uniform heating and uniform cooling is 10°C / min.

[0048] The amount of high-temperature sintered lithium source added is 5000ppm of Li element; the lithium source material is lithium carbonate.

[0049] The mesh size of the secondary sieve is 325 meshes.

[0050] During the water washing, the mass ratio of the tertiary powder to water is 0.3:1.

[0051] Comparative Example 2

[0052] Comparative Example 2 of the present invention provides a uniform and efficient wet method for repairing lithium cobalt oxide, wherein the powder on the positive electrode sheet of the recycled waste lithium cobalt oxide battery is separated from the foil, and the first-level powder is obtained after the first-level screening to remove the magnetism, and the first-level powder is sintered at high temperature to obtain the third-level powder, and the third-level powder is crushed, screened and demagnetized, washed and dried. The difference from Comparative Example 1 is that the temperature of high-temperature sintering is 880°C, and the specific steps are as follows:

[0053] The recycled waste lithium cobalt oxide batteries come from battery factories.

[0054] The separation temperature is 250° C. and the separation time is 3 h.

[0055] The first-stage screen and the second-stage screen are both ultrasonic vibrating screens, and the demagnetizing instrument is an electromagnetic iron remover.

[0056] The particle size of the primary powder is 100 meshes.

[0057] The drying conditions are as follows: temperature is 120° C. and drying time is 5 h.

[0058] The temperature of the high temperature sintering is 880°C, and the time of the high temperature sintering is 10 hours. The high temperature sintering adopts uniform heating and uniform cooling; the rate of the uniform heating and uniform cooling is 10°C / min.

[0059] The amount of lithium source added for high temperature sintering is 5000ppm of Li element; the lithium source material is lithium carbonate.

[0060] The mesh size of the secondary sieve is 325 meshes.

[0061] During the water washing, the mass ratio of the tertiary powder to water is 0.3:1.

[0062] Comparative Example 3

[0063] Comparative Example 3 of the present invention provides a uniform and efficient wet method for repairing lithium cobalt oxide, wherein the powder on the positive electrode sheet of the recycled waste lithium cobalt oxide battery is separated from the foil, and the first-level powder is obtained after the first-level screening to remove the magnetism, and the first-level powder is sintered at high temperature to obtain the third-level powder, and the third-level powder is crushed, screened and demagnetized, washed and dried. The difference from Comparative Example 1 is that the amount of lithium source added for high-temperature sintering is 1000ppm of Li element, and the specific steps are as follows:

[0064] The recycled waste lithium cobalt oxide batteries come from battery factories.

[0065] The separation temperature is 250° C. and the separation time is 3 h.

[0066] The first-stage screen and the second-stage screen are both ultrasonic vibrating screens, and the demagnetizing instrument is an electromagnetic iron remover.

[0067] The particle size of the primary powder is 100 meshes.

[0068] The drying conditions are as follows: temperature is 120° C. and drying time is 5 h.

[0069] The high temperature sintering temperature is 980°C, the high temperature sintering time is 10 hours, and the high temperature sintering adopts uniform heating and uniform cooling; the rate of uniform heating and uniform cooling is 10°C / min.

[0070] The amount of lithium source added for high temperature sintering is 1000ppm of Li element; the lithium source material is lithium carbonate.

[0071] The mesh size of the secondary sieve is 325 meshes.

[0072] During the water washing, the mass ratio of the tertiary powder to water is 0.3:1.

[0073] Performance Testing Methods

[0074] 1. The lithium cobalt oxide positive electrode materials after repair in the embodiment and the comparative example were characterized by scanning electron microscopy. The results are shown in Figure 1 , Figure 2 .

[0075] 2. The repaired lithium cobalt oxide positive electrode materials of the embodiment and the comparative example were assembled into button-type CR2032 half-cells and tested at a current density of 0.2C at a voltage of 3.0V-4.4V. The test results are shown in Figure 3It can be seen that the first discharge specific capacity of Example 1 is 177.2 mAh / g, the first discharge specific capacity of Comparative Example 1 is 165.4 mAh / g, the first discharge specific capacity of Comparative Example 2 is 167.1 mAh / g, and the first discharge specific capacity of Comparative Example 3 is 163.7 mAh / g. The first discharge specific capacity of Example 1 is increased by 11.8 mAh / g compared with Comparative Example 1, increased by 10.1 mAh / g compared with Comparative Example 2, and increased by 13.5 mAh / g compared with Comparative Example 3.

Claims

1. A uniform and efficient wet method for repairing lithium cobalt oxide, characterized in that: The powder on the positive electrode sheet of the recycled waste lithium cobalt oxide battery is separated from the foil, and the first-level powder is obtained after the magnetism is removed by a first-level sieve, and the first-level powder is mixed with an additive to obtain a second-level mixture, and the second-level mixture is filtered, dried, crushed, and then sintered at a high temperature to obtain a third-level powder, and the third-level powder is crushed, passed through a second-level sieve to remove the magnetism, washed with water, and then dried; The recycled waste lithium cobalt oxide batteries come from battery factories; The separation temperature is 250°C and the separation time is 3h; The first-stage screen and the second-stage screen are both ultrasonic vibrating screens, and the demagnetizing instrument is an electromagnetic iron remover; The particle size of the primary powder is 100 mesh; The additive is an inorganic salt aqueous solution with a concentration of 1.3 mol / L; the inorganic salt aqueous solution is a Na2CO3 aqueous solution; The solid content of the secondary mixture is 30wt%; The drying conditions are: temperature is 120°C, and the drying time is 5h; The high temperature sintering temperature is 980°C, and the high temperature sintering time is 10h; the high temperature sintering adopts uniform heating and uniform cooling; the rate of uniform heating and uniform cooling is 10°C / min; The amount of the high temperature sintered lithium source added is 5000ppm of Li element; the lithium source material is lithium carbonate; The mesh size of the secondary sieve is 325 mesh; During the water washing, the mass ratio of the tertiary powder to water is 0.3:

1.

2. An application of the uniform and efficient wet method for repairing lithium cobalt oxide according to claim 1, characterized in that: Used for the repair of lithium cobalt oxide positive electrode materials in waste batteries.

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