Method for recycling and regenerating positive electrode material of waste lithium battery

Abstract

The application discloses a kind of waste lithium battery positive electrode material recycling method, it is related to lithium battery positive electrode material technical field.The application is in preparation lithium battery positive electrode material, first waste lithium iron phosphate battery is discharged and disassembled, and in cold hot water circulation immersion separation current collector, after calcination, with sulfuric acid-hydrogen peroxide selection leaching lithium ion is recovered to obtain recycled lithium carbonate;Carbonate ternary precursor is prepared by coprecipitation method;Carbonate ternary precursor, recycled lithium carbonate, silicon monoxide, lithium fluoride, neodymium oxide are mixed and secondly calcined to obtain doped modified ternary positive electrode material;Lanthanum, aluminum and zinc are coated on the surface of doped modified ternary positive electrode material by potassium-sodium alloy reduction method to obtain coated modified ternary positive electrode material;Coated modified ternary positive electrode material is mixed with conductive agent and binder, and then coated on carbon-coated aluminum foil to obtain lithium battery positive electrode material.The lithium battery positive electrode material prepared by the application has high charge-discharge specific capacity, high cycle life and good rate performance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of lithium battery positive electrode materials, in particular to a method for recycling and regenerating waste lithium battery positive electrode materials. BACKGROUND

[0002] With the rapid growth of population and the leapfrog development of economy in various countries around the world, there is an urgent and significant demand for more sustainable and multifunctional energy supply in modern society. Nowadays, most of the energy in the world comes from fossil fuels, which is a non-renewable energy source, which inevitably leads to the emergence of energy crisis and the aggravation of environmental pollution. Therefore, more sustainable and green energy is increasingly valued by people, which is usually collected in the form of electrical energy from wind energy, solar energy, tides or water energy. Therefore, various types of batteries, especially lithium ion batteries, which store and release electrical energy through reversible insertion and extraction of lithium ions in the positive and negative electrodes, are manufactured and applied on a large scale.

[0003] Power batteries are one of the most core components in the structure of new energy vehicles, accounting for 30% to 40% of the cost of the whole vehicle. The most commonly used power batteries in current new energy vehicles are nickel-cobalt-manganese ternary batteries with a layered structure and lithium iron phosphate batteries with an olivine structure. Among them, in the early development of new energy vehicles in China, lithium iron phosphate batteries were considered to be more promising among various lithium ion batteries due to their excellent safety performance, long enough cycle life and lower manufacturing cost than other batteries, and were more loaded in various types of commercial passenger cars and family cars. With the continuous increase of service life, lithium ion batteries are increasingly close to the retirement period. Generally speaking, when the actual capacity of the power battery decays to about 80% of its rated value, it needs to be retired. Due to the wide popularity of early new energy vehicles, a large number of retired power batteries will soon flood the market.

[0004] Waste lithium-ion batteries contain numerous substances that may harm human health and the ecological environment, including large amounts of heavy metals and electrolyte solutions such as spent acids and alkalis. Leakage of heavy metals from waste lithium-ion batteries can pollute rivers, lakes, and oceans, impacting aquatic life, natural resource utilization, and indirectly impacting human health. Acids, alkalis, and electrolytes in the waste can also cause soil erosion, leading to acidification and salinization. However, it's worth noting that waste lithium batteries themselves contain a significant amount of metal resources, such as iron, lithium, and aluminum. Lithium metal accounts for approximately 1%, exceeding the content of typical lithium ore, making them highly valuable for recycling. Therefore, the end of the service life of new energy vehicle power batteries doesn't necessarily mean the end of their lifespan; rather, they can be transformed into valuable assets. Recycling lithium metal from waste lithium batteries not only improves the comprehensive utilization rate of lithium resources and effectively alleviates pressure on lithium reserves, but also enhances the sustainable development of green industries such as new energy electric vehicles and energy storage power plants. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for recycling and regenerating waste lithium battery positive electrode materials to solve the problems existing in the prior art.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A lithium battery positive electrode material is prepared by mixing a coated modified ternary positive electrode material with a conductive agent and a binder and then coating the mixture on a carbon-coated aluminum foil;

[0008] The coated modified ternary positive electrode material is prepared by mixing lanthanum acetylacetonate, zinc acetylacetonate, aluminum acetylacetonate, and a doped modified ternary positive electrode material, shearing the mixture at high speed, adding a potassium-sodium alloy for reduction, and then calcining the mixture.

[0009] The doped modified ternary cathode material is prepared by mixing a ternary carbonate precursor, recycled lithium carbonate, silicon dioxide, lithium fluoride, and neodymium oxide, and then calcining the mixture twice;

[0010] The lithium carbonate is recovered by disassembling the waste lithium iron phosphate battery after discharge, immersing the separated current collector in hot and cold water in a cycle, calcining it, and then selectively leaching the lithium ions with sulfuric acid-hydrogen peroxide for recovery;

[0011] The ternary carbonate precursor is prepared by mixing a nickel source, a cobalt source and a manganese source to form a mixed salt solution, and then adding a precipitant solution under the complexation action of ammonia water to carry out co-precipitation.

[0012] As an optimization, the nickel source is nickel sulfate heptahydrate; the cobalt source is cobalt sulfate hexahydrate; and the manganese source is manganese sulfate monohydrate.

[0013] As an optimization, the mixed salt solution is prepared by dissolving the nickel source, the cobalt source, and the manganese source in pure water at a molar ratio of 6:2:2 to form a 2 mol / L mixed salt solution.

[0014] As an optimization, the precipitant solution is prepared by mixing 1 mol / L sodium carbonate solution and 1 mol / L ammonium bicarbonate solution in a volume ratio of 1:1.

[0015] A method for recycling and regenerating waste lithium battery positive electrode materials, comprising the following preparation steps:

[0016] (1) After the waste lithium iron phosphate battery is discharged and inactivated, it is manually disassembled to separate the lithium iron phosphate positive electrode sheet, and the lithium iron phosphate positive electrode sheet is soaked in hot water and cold water in turn, each soaking for 2 to 3 minutes, and the soaking cycle is repeated until the current collector is detached to obtain a lithium iron phosphate positive electrode material, and dimethylformamide is added to the lithium iron phosphate positive electrode material at a liquid-solid ratio of 3:1 g / g and mixed evenly, and calcined at 450 to 500 ° C for 2 to 3 hours under an argon atmosphere, cooled naturally to room temperature, crushed and ground, and passed through a 100 mesh sieve to obtain a lithium iron phosphate positive electrode material powder;

[0017] (2) By weight, 2 to 3 parts of lithium iron phosphate positive electrode material powder, 4 to 6 parts of hydrogen peroxide, 16 to 24 parts of 0.4 mol / L sulfuric acid solution, and 80 to 120 parts of pure water were mixed evenly, stirred at 68 to 72 ° C and 250 to 350 r / min for 30 to 40 minutes, filtered, and the residue was separated for iron recovery. The filtrate was concentrated to a lithium ion concentration of 30 g / L, and the pH was adjusted to 10 with sodium hydroxide solution. Saturated sodium carbonate solution was added at 90 ° C and 300 to 400 r / min at a sodium carbonate to lithium ion molar ratio of (1.2 to 1.4): 1. After the addition was completed, stirring was continued for 60 to 80 minutes, filtered, washed with boiling pure water for 3 to 4 times, and vacuum dried at 70 to 80 ° C for 10 to 12 hours to obtain recovered lithium carbonate;

[0018] (3) First, add 20 to 30 parts of pure water by mass, and at 60 to 70°C, 500 to 600 r / min, add 40 to 50 parts of mixed salt solution, 20 to 30 parts of ammonia water, and 50 to 60 parts of precipitant solution simultaneously, control the flow rate ratio of the mixed salt solution and ammonia water to be 2:1, control the flow rate of the precipitant solution to control the pH at 7.5 to 8, react for 8 to 10 hours after all are added, stop stirring, seal and age in a water bath at 60 to 70°C for 12 to 14 hours, filter, wash with pure water until the pH is less than 7.5, vacuum dry at 60 to 70°C for 6 to 8 hours, crush and grind, and pass through a 120-mesh sieve to obtain a ternary carbonate precursor;

[0019] (4) According to the mass ratio, 20 to 30 parts of carbonate ternary precursor, 6.39 to 9.39 parts of recovered lithium carbonate, 0.075 to 0.112 parts of silicon dioxide, 0.176 to 0.396 parts of lithium fluoride, and 2.85 to 4.28 parts of neodymium oxide are mixed evenly, added to a ball mill, ground at 50 to 60 r / min for 5 to 6 hours, passed through a 200 mesh sieve, heated to 450 to 500 ° C at a heating rate of 3 to 4 ° C / min in an oxygen atmosphere, calcined for 4 to 5 hours, cooled naturally to room temperature, and passed through a 200 mesh sieve after grinding. In an oxygen atmosphere, the temperature is continuously increased to 800 to 850 ° C at a heating rate of 3 to 4 ° C / min and calcined for 16 to 18 hours, cooled naturally to room temperature, and passed through a 325 mesh sieve after grinding to obtain a doped modified ternary positive electrode material;

[0020] (5) By weight, 0.064-0.085 parts of lanthanum acetylacetonate, 0.039-0.051 parts of zinc acetylacetonate, 0.048-0.063 parts of aluminum acetylacetonate, 3-4 parts of doped modified ternary cathode material, and 50-60 parts of ethylene glycol dimethyl ether were mixed uniformly, ultrasonicated for 15-20 minutes, stirred at 1200-1400 r / min for 3-4 minutes under an argon atmosphere, and 0.6-0.8 parts of potassium-sodium alloy were added. , continue stirring for 15 to 20 minutes, centrifuge at 8000 to 10000 rpm for 8 to 10 minutes, wash the solid with ethylene glycol dimethyl ether 2 to 3 times, vacuum dry at 60 to 70 ° C for 6 to 8 hours, crush and grind, pass through a 325 mesh sieve, and heat to 800 to 850 ° C at a heating rate of 3 to 4 ° C / min in an air atmosphere and calcine for 4 to 5 hours, cool naturally to room temperature, grind and pass through a 325 mesh sieve to obtain a coated modified ternary positive electrode material;

[0021] (6) The coated modified ternary positive electrode material, conductive agent and binder are mixed evenly in a mass ratio of 8:1:1, poured into a ball mill, stirred for 10 to 15 minutes using a high-speed swing ball mill, and 3.5 times the total mass of N-methylpyrrolidone is added. The mixture is stirred at 300 to 400 r / min for 3 to 4 hours, evenly applied on a carbon-coated aluminum foil, and vacuum dried at 60°C for 3 to 4 hours, and then vacuum dried at 120°C for 10 to 12 hours to obtain a lithium battery positive electrode material.

[0022] As an optimization, the hot water in step (1) is 80-90°C, and the cold water is 10-20°C.

[0023] As an optimization, the concentration of the hydrogen peroxide in step (2) is 30 wt%.

[0024] As an optimization, the concentration of the sodium hydroxide solution in step (2) is 0.5 mol / L.

[0025] As an optimization, the ammonia concentration in step (3) is 1 mol / L.

[0026] As an optimization, the mass ratio of potassium to sodium in the potassium-sodium alloy in step (5) is 3:1.

[0027] As an optimization, the conductive agent in step (6) is acetylene black, and the median diameter is 1 to 3 μm.

[0028] As an optimization, the binder in step (6) is polyvinylidene fluoride, model number Kynar 741.

[0029] As an optimization, the carbon-coated aluminum foil in step (6) was purchased from Guangzhou Nano New Materials Technology Co., Ltd.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention prepares the positive electrode material of a lithium battery by first disassembling the waste lithium iron phosphate battery after discharge, circulately soaking the separated current collector in hot and cold water, calcining, selectively leaching lithium ions with sulfuric acid-hydrogen peroxide to recover lithium carbonate; mixing a nickel source, a cobalt source and a manganese source to form a mixed salt solution, adding a precipitant solution under the complexation action of ammonia water to carry out co-precipitation to obtain a ternary carbonate precursor; mixing the ternary carbonate precursor, recovered lithium carbonate, silicon dioxide, lithium fluoride and neodymium oxide, and then calcining twice to obtain a doped modified ternary positive electrode material; mixing lanthanum acetylacetonate, zinc acetylacetonate, aluminum acetylacetonate and the doped modified ternary positive electrode material, shearing the mixture at high speed, adding potassium sodium alloy for reduction and calcining to obtain a coated modified ternary positive electrode material; mixing the coated modified ternary positive electrode material with a conductive agent and a binder, and coating the mixture on a carbon-coated aluminum foil to obtain the positive electrode material of a lithium battery.

[0032] First, the waste lithium iron phosphate battery is disassembled after discharge, and the current collector is separated by circulating in hot and cold water. After calcination, lithium ions are selectively leached with sulfuric acid-hydrogen peroxide to recover the recovered lithium carbonate. After the waste lithium iron phosphate battery is discharged and inactivated, it can be safely disassembled manually. Taking advantage of the large difference in thermal expansion coefficient between the binder and the aluminum foil current collector, the binder is completely separated from the aluminum foil current collector by circulating in hot and cold water, reducing the residual aluminum impurities in the positive electrode material, avoiding the use of chemical reagents, and reducing emissions. Dimethylformamide is then added to assist mixing. Afterwards, high-temperature calcination is carried out to completely remove impurities such as binders in the positive electrode material, retaining the complete positive electrode active material. Subsequently, leaching is carried out using a sulfuric acid-hydrogen peroxide system. The parameters are optimized so that the leaching rate of lithium ions reaches more than 98%, while the leaching rate of iron ions is less than 0.5%. The iron element is enriched in the filter residue and can be recovered later. The lithium ions in the filtrate are concentrated and recovered by precipitation with sodium carbonate. The first precipitation rate is greater than 89%. The purity of the recovered lithium carbonate is greater than 99.5%, which meets battery-grade standards and can be used for subsequent regeneration preparation of positive electrode materials.

[0033] Secondly, the nickel source, cobalt source and manganese source are mixed into a mixed salt solution, and then a precipitant solution is added under the complexation action of ammonia water to perform co-precipitation to obtain a carbonate ternary precursor. The mixed salt solution of nickel source, cobalt source and manganese source is added in parallel with ammonia water and precipitant solution to optimize the nucleation and crystallization path of the precipitation, which can improve the electrical properties of the lithium battery positive electrode material prepared subsequently. At the same time, as for the precipitant solution, instead of using a simple sodium carbonate solution, a mixed solution of sodium carbonate and ammonium bicarbonate is used. The pH of the simple sodium carbonate solution is greater than the pH of the mixed solution of sodium carbonate and ammonium bicarbonate, which will cause nickel hydroxide to appear in the precursor. The impurity phase causes the electrical performance of the subsequent lithium battery positive electrode material to decline; the carbonate ternary precursor, recycled lithium carbonate, silicon oxide, lithium fluoride, and neodymium oxide are mixed and calcined twice to obtain a doped modified ternary positive electrode material. Silicon oxide, lithium fluoride, and neodymium oxide are mixed during high-temperature calcination to dope fluorine, silicon, and neodymium elements into the lithium battery positive electrode material. The doping of neodymium element inhibits the mixing of lithium and nickel, increases the lattice spacing, expands the lithium ion transmission channel, reduces the lithium ion deintercalation barrier and accelerates electron migration. At the same time, the doping of fluorine further enhances the inhibitory effect on the mixing of lithium and nickel. At the same time, the electronegativity of fluorine is stronger than that of oxygen. The strength of the lithium-fluorine bond is greater, the crystal configuration is more stable during repeated charge and discharge, and the cycle performance is also improved. The doped fluorine can also inhibit the damage of hydrofluoric acid in the electrolyte to the positive electrode material to a certain extent, and the trace doping of silicon further expands the lattice spacing, which is conducive to the rapid migration of lithium ions. At the same time, the doping of silicon regulates the radial growth of the primary calcined particles, showing an elongated nano-needle structure. The spherical secondary particles stacked thereby are conducive to reducing the concentration of interfacial stress, and increasing the transmission rate of lithium ions, thereby improving electrical properties. At the same time, the doping of silicon is conducive to resisting the corrosion of the electrolyte. And delay the collapse of the crystal structure. In the co-doping of fluorine, silicon and neodymium, on the one hand, the strong electronegativity of fluorine ions and the synergistic effect of the support of silicon and neodymium make the structural stability better during the charging and discharging process. On the other hand, in order to balance the increase in valence caused by the combined doping of fluorine ions and neodymium ions, the number of low-valent transition metal ions is increased, the unit cell volume is increased, the diffusion channel of lithium ions is expanded, and the electrical properties are improved; in the calcination process, the secondary calcination method is used, first pre-burning at a low temperature and then grinding, so that the various metal elements are further evenly mixed, the regularity of crystal growth is improved, which is beneficial to the improvement of electrical properties.

[0034] Finally, lanthanum acetylacetonate, zinc acetylacetonate, aluminum acetylacetonate, and a doped modified ternary cathode material are mixed and sheared at high speed, and potassium-sodium alloy is added for reduction and calcined to obtain a coated modified ternary cathode material. The high reducibility of potassium-sodium alloy is utilized to jointly coat lanthanum, zinc, and aluminum elements on the surface of the doped modified ternary cathode material. At the same time, the high-speed shear force is utilized to make the coating more uniform. At the same time, the process conditions are simple and controllable. The obtained lanthanum, zinc, and aluminum composite oxide coating layer can effectively reduce the corrosion effect of the electrolyte on the cathode material, reduce the occurrence of side reactions, protect the integrity and regularity of the material, and effectively extend the cycle life. At the same time, the multi-metal oxide coating layer can give full play to the synergistic effect between transition metals, on the one hand, promoting the permeation of ions and electrons and increasing the conductivity, and on the other hand, effectively weakening the interface impedance and improving the rate performance. The coated modified ternary cathode material is mixed with a conductive agent and a binder and then coated on a carbon-coated aluminum foil to obtain a lithium battery cathode material. DETAILED DESCRIPTION

[0035] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] Example 1:

[0037] A method for recycling and regenerating positive electrode materials of waste lithium batteries, comprising the following steps:

[0038] (1) After the waste lithium iron phosphate battery is discharged and inactivated, it is manually disassembled to separate the lithium iron phosphate positive electrode sheet, and the lithium iron phosphate positive electrode sheet is soaked in 80°C hot water and 20°C cold water in turn, each soaking for 3 minutes, and the soaking cycle is repeated until the current collector is detached to obtain a lithium iron phosphate positive electrode material, and dimethylformamide is added to the lithium iron phosphate positive electrode material at a liquid-solid ratio of 3:1g / g and mixed evenly, and calcined at 450°C for 3h under an argon atmosphere, naturally cooled to room temperature, crushed and ground, and passed through a 100-mesh sieve to obtain a lithium iron phosphate positive electrode material powder;

[0039] (2) By weight, 2 parts of lithium iron phosphate positive electrode material powder, 4 parts of hydrogen peroxide, 16 parts of 0.4 mol / L sulfuric acid solution, and 80 parts of pure water were mixed evenly, stirred at 68°C and 250 r / min for 40 min, filtered, and the residue was separated for iron recovery. The filtrate was concentrated to a lithium ion concentration of 30 g / L, and the pH was adjusted to 10 with sodium hydroxide solution. Saturated sodium carbonate solution was added at 90°C and 300 r / min at a sodium carbonate to lithium ion molar ratio of 1.2:1. After the addition was completed, stirring was continued for 80 min, filtered, washed with boiling pure water 3 times, and vacuum dried at 70°C for 12 h to obtain recovered lithium carbonate;

[0040] (3) First, add 20 parts of pure water by mass, and then add 40 parts of mixed salt solution, 20 parts of ammonia water, and 50 parts of precipitant solution at 60°C and 500r / min. The flow rate ratio of the mixed salt solution and ammonia water is controlled to be 2:1. The flow rate of the precipitant solution is controlled to control the pH at 7.5. After all the addition is completed, react for 8 hours, stop stirring, seal and age in a water bath at 60°C for 14 hours, filter, wash with pure water until the pH is less than 7.5, vacuum dry at 60°C for 8 hours, crush and grind, and pass through a 120-mesh sieve to obtain a ternary carbonate precursor;

[0041] (4) According to the mass ratio, 20 parts of carbonate ternary precursor, 6.39 parts of recycled lithium carbonate, 0.075 parts of silicon dioxide, 0.176 parts of lithium fluoride, and 2.85 parts of neodymium oxide were mixed evenly, added to a ball mill, ground at 50r / min for 6h, passed through a 200-mesh sieve, heated to 450°C at a heating rate of 3°C / min in an oxygen atmosphere, and calcined for 5h, cooled naturally to room temperature, and passed through a 200-mesh sieve after grinding. In an oxygen atmosphere, the temperature was continued to be raised to 800°C at a heating rate of 3°C / min and calcined for 18h, cooled naturally to room temperature, and passed through a 325-mesh sieve after grinding to obtain a doped modified ternary positive electrode material;

[0042] (5) By weight, 0.064 parts of lanthanum acetylacetonate, 0.039 parts of zinc acetylacetonate, 0.048 parts of aluminum acetylacetonate, 3 parts of doped modified ternary cathode material, and 50 parts of ethylene glycol dimethyl ether were mixed evenly, ultrasonicated for 15 minutes, stirred at 1200 r / min for 4 minutes under an argon atmosphere, 0.6 parts of potassium sodium alloy were added, and stirring was continued for 15 minutes. The mixture was centrifuged at 8000 rpm for 10 minutes, and the solid was washed twice with ethylene glycol dimethyl ether, dried in vacuo at 60°C for 8 hours, crushed and ground, and passed through a 325-mesh sieve. In an air atmosphere, the mixture was heated to 800°C at a heating rate of 3°C / min and calcined for 5 hours. The mixture was naturally cooled to room temperature, ground and passed through a 325-mesh sieve to obtain a coated modified ternary cathode material.

[0043] (6) The coated modified ternary positive electrode material, the conductive agent, and the binder are mixed uniformly in a mass ratio of 8:1:1, poured into a ball mill tank, stirred for 10 min using a high-speed swing ball mill, 3.5 times the total mass of N-methylpyrrolidone is added, stirred at 300 r / min for 4 h, uniformly coated on a carbon-coated aluminum foil, vacuum dried at 60℃ for 3 h, and then vacuum dried at 120℃ for 10 h to obtain a lithium battery positive electrode material.

[0044] Example 2:

[0045] A method for recycling and regenerating a waste lithium battery positive electrode material, the method comprising the following preparation steps:

[0046] (1) After discharging and deactivating the waste lithium iron phosphate battery, lithium iron phosphate positive electrode sheets are separated by hand disassembly, the lithium iron phosphate positive electrode sheets are sequentially soaked in 85℃ hot water and 15℃ cold water, each time for 2.5 min, and the cycle soaking is continued until the current collector is separated, to obtain a lithium iron phosphate positive electrode material, dimethylformamide is added to the lithium iron phosphate positive electrode material in a liquid-solid ratio of 3:1 g / g, mixed uniformly, calcined at 475℃ for 2.5 h under an argon atmosphere, naturally cooled to room temperature, crushed and ground to pass through a 100 mesh sieve, and a lithium iron phosphate positive electrode material powder is prepared;

[0047] (2) 2.5 parts of the lithium iron phosphate positive electrode material powder, 5 parts of hydrogen peroxide, 20 parts of a 0.4 mol / L sulfuric acid solution, and 100 parts of pure water are mixed uniformly, stirred at 70℃ and 300 r / min for 35 min, filtered, and the filter residue is separated for recycling iron, the filtrate is concentrated to a lithium ion concentration of 30 g / L, the pH is adjusted to 10 with a sodium hydroxide solution, a saturated sodium carbonate solution is added at a molar ratio of sodium carbonate to lithium ion of 1.3:1 at 90℃ and 350 r / min, stirring is continued for 70 min after the addition is completed, filtered, washed with boiling pure water 3 times, and vacuum dried at 75℃ for 11 h to obtain recycled lithium carbonate;

[0048] (3) 25 parts of pure water are first added, 45 parts of a mixed salt solution, 25 parts of ammonia water, and 55 parts of a precipitant solution are simultaneously added at 65℃ and 550 r / min, the flow rate ratio of the mixed salt solution to the ammonia water is controlled at 2:1, the pH of the precipitant solution is controlled at 7.8 by controlling the flow rate, the reaction is continued for 9 h after the addition is completed, the stirring is stopped, the sealed sample is aged at 65℃ for 13 h, filtered, washed with pure water until the pH is less than 7.5, vacuum dried at 65℃ for 7 h, crushed and ground, and passed through a 120 mesh sieve to obtain a carbonated ternary precursor;

[0049] (4) According to the mass ratio, 25 parts of carbonate ternary precursor, 7.91 parts of recycled lithium carbonate, 0.093 parts of silicon dioxide, 0.275 parts of lithium fluoride, and 3.56 parts of neodymium oxide were mixed evenly, added to a ball mill, ground at 55r / min for 5.5h, passed through a 200-mesh sieve, heated to 475℃ at a heating rate of 4℃ / min in an oxygen atmosphere, and calcined for 4.5h. After cooling to room temperature naturally, after grinding, the mixture was passed through a 200-mesh sieve, and continued to heat to 825℃ at a heating rate of 4℃ / min in an oxygen atmosphere and calcined for 17h. After cooling to room temperature naturally, the mixture was passed through a 325-mesh sieve to obtain a doped modified ternary positive electrode material;

[0050] (5) By weight, 0.075 parts of lanthanum acetylacetonate, 0.045 parts of zinc acetylacetonate, 0.055 parts of aluminum acetylacetonate, 3.5 parts of doped modified ternary cathode material, and 55 parts of ethylene glycol dimethyl ether were mixed evenly, ultrasonicated for 18 minutes, stirred at 1300 r / min for 3.5 minutes under an argon atmosphere, 0.7 parts of potassium sodium alloy were added, and stirring was continued for 18 minutes. The mixture was centrifuged at 9000 rpm for 9 minutes, and the solid was washed 3 times with ethylene glycol dimethyl ether, vacuum-dried at 65°C for 7 hours, crushed and ground, and passed through a 325-mesh sieve. In an air atmosphere, the mixture was heated to 825°C at a heating rate of 4°C / min and calcined for 4.5 hours. The mixture was naturally cooled to room temperature, ground and passed through a 325-mesh sieve to obtain a coated modified ternary cathode material.

[0051] (6) The coated modified ternary positive electrode material, conductive agent, and binder were mixed evenly in a mass ratio of 8:1:1, poured into a ball mill, and stirred for 12 minutes using a high-speed swing ball mill. N-methylpyrrolidone (3.5 times the total mass) was added and stirred at 350 r / min for 3.5 hours. The mixture was evenly spread on a carbon-coated aluminum foil, vacuum-dried at 60°C for 3.5 hours, and then vacuum-dried at 120°C for 11 hours to obtain a lithium battery positive electrode material.

[0052] Example 3:

[0053] A method for recycling and regenerating positive electrode materials of waste lithium batteries, comprising the following steps:

[0054] (1) After the waste lithium iron phosphate battery is discharged and inactivated, it is manually disassembled to separate the lithium iron phosphate positive electrode sheet, and the lithium iron phosphate positive electrode sheet is soaked in 90°C hot water and 10°C cold water in turn, each soaking for 2 minutes, and the soaking cycle is repeated until the current collector is detached to obtain a lithium iron phosphate positive electrode material, and dimethylformamide is added to the lithium iron phosphate positive electrode material at a liquid-solid ratio of 3:1g / g and mixed evenly, and calcined at 500°C for 2h under an argon atmosphere, naturally cooled to room temperature, crushed and ground, and passed through a 100-mesh sieve to obtain a lithium iron phosphate positive electrode material powder;

[0055] (2) By weight, 3 parts of lithium iron phosphate positive electrode material powder, 6 parts of hydrogen peroxide, 24 parts of 0.4 mol / L sulfuric acid solution, and 120 parts of pure water were mixed evenly, stirred at 72°C and 350 r / min for 30 min, filtered, and the residue was separated for iron recovery. The filtrate was concentrated to a lithium ion concentration of 30 g / L, and the pH was adjusted to 10 with sodium hydroxide solution. Saturated sodium carbonate solution was added at 90°C and 400 r / min at a sodium carbonate to lithium ion molar ratio of 1.4:1. After the addition was completed, stirring was continued for 60 min, filtered, washed with boiling pure water 4 times, and vacuum dried at 80°C for 10 h to obtain recovered lithium carbonate;

[0056] (3) First, add 30 parts of pure water by mass, then add 50 parts of mixed salt solution, 30 parts of ammonia water, and 60 parts of precipitant solution at 70°C and 600 r / min, control the flow rate ratio of mixed salt solution and ammonia water to be 2:1, control the flow rate of precipitant solution to control the pH at 8, react for 10 hours after all are added, stop stirring, seal and age in a 70°C water bath for 12 hours, filter, wash with pure water until the pH is less than 7.5, vacuum dry at 70°C for 6 hours, crush and grind, and pass through a 120-mesh sieve to obtain a ternary carbonate precursor;

[0057] (4) By weight, 30 parts of carbonate ternary precursor, 9.39 parts of recycled lithium carbonate, 0.112 parts of silicon dioxide, 0.396 parts of lithium fluoride, and 4.28 parts of neodymium oxide were mixed evenly, added to a ball mill, ground at 60 r / min for 5 h, passed through a 200-mesh sieve, heated to 500 ° C at a heating rate of 4 ° C / min in an oxygen atmosphere, and calcined for 4 h. After naturally cooling to room temperature, after grinding, the mixture was passed through a 200-mesh sieve, and continued to heat to 850 ° C at a heating rate of 4 ° C / min in an oxygen atmosphere and calcined for 16 h. After naturally cooling to room temperature, the mixture was ground and passed through a 325-mesh sieve to obtain a doped modified ternary positive electrode material;

[0058] (5) By weight, 0.085 parts of lanthanum acetylacetonate, 0.051 parts of zinc acetylacetonate, 0.063 parts of aluminum acetylacetonate, 4 parts of doped modified ternary cathode material, and 60 parts of ethylene glycol dimethyl ether were mixed evenly, ultrasonicated for 20 minutes, stirred at 1400 r / min for 3 minutes under an argon atmosphere, 0.8 parts of potassium sodium alloy were added, and stirring was continued for 20 minutes. The mixture was centrifuged at 10000 rpm for 8 minutes, and the solid was washed 3 times with ethylene glycol dimethyl ether, vacuum-dried at 70 ° C for 6 hours, crushed and ground, and passed through a 325 mesh sieve. In an air atmosphere, the temperature was increased to 850 ° C at a heating rate of 4 ° C / min and calcined for 4 hours. The mixture was naturally cooled to room temperature, ground and passed through a 325 mesh sieve to obtain a coated modified ternary cathode material;

[0059] (6) The coated modified ternary positive electrode material, conductive agent, and binder were mixed evenly in a mass ratio of 8:1:1, poured into a ball mill, and stirred for 15 minutes using a high-speed swing ball mill. N-methylpyrrolidone 3.5 times the total mass was added and stirred at 400 r / min for 3 hours. The mixture was evenly spread on a carbon-coated aluminum foil, vacuum-dried at 60°C for 4 hours, and then vacuum-dried at 120°C for 12 hours to obtain a lithium battery positive electrode material.

[0060] Comparative Example 1:

[0061] The difference between the method for recycling and regenerating the positive electrode material of waste lithium batteries in Comparative Example 1 and Example 2 lies in the difference in step (3). Step (3) is modified as follows: by mass, 25 parts of pure water are first added, and at 65°C, 550r / min, 45 parts of a mixed salt solution are first added, 25 parts of ammonia water are added dropwise at a rate of 2 drops per second, and stirring is continued for 30 minutes after the addition is completed. Then, a precipitant solution is added dropwise at a rate of one drop per 4 seconds to adjust the pH to 7.8. After all the addition is completed, the reaction is carried out for 9 hours, stirring is stopped, and the mixture is sealed and aged in a 65°C water bath for 13 hours. The mixture is filtered, washed with pure water until the pH is less than 7.5, vacuum dried at 65°C for 7 hours, crushed and ground, and passed through a 120-mesh sieve to obtain a ternary carbonate precursor. The remaining steps are the same as in Example 2.

[0062] Comparative Example 2:

[0063] The difference between the method for recycling and regenerating waste lithium battery positive electrode materials in Comparative Example 2 and Example 2 is that the precipitant used in step (3) is a 1 mol / L sodium carbonate solution. The remaining steps are the same as in Example 2.

[0064] Comparative Example 3:

[0065] The difference between the method for recycling and regenerating waste lithium battery positive electrode materials in Comparative Example 3 and Example 2 lies in the difference in step (4). Step (4) is modified as follows: 25 parts of ternary carbonate precursor, 7.91 parts of recovered lithium carbonate, 0.093 parts of silicon dioxide, 0.275 parts of lithium fluoride, and 3.56 parts of neodymium oxide are mixed uniformly by mass, added to a ball mill, ground at 55 r / min for 5.5 hours, passed through a 200 mesh sieve, and heated to 475°C at a heating rate of 4°C / min in an oxygen atmosphere and calcined for 4.5 hours. The temperature is further increased to 825°C at a heating rate of 4°C / min and calcined for 17 hours. The material is naturally cooled to room temperature, ground, and passed through a 325 mesh sieve to obtain a doped modified ternary positive electrode material. The remaining steps are the same as in Example 2.

[0066] Comparative Example 4:

[0067] The difference between the method for recycling and regenerating waste lithium battery positive electrode materials in Comparative Example 4 and Example 2 lies in the difference in step (4). Step (4) is modified as follows: 25 parts of ternary carbonate precursor, 7.91 parts of recovered lithium carbonate, 0.093 parts of silicon dioxide, 0.275 parts of lithium fluoride, and 3.56 parts of neodymium oxide are mixed uniformly by mass, added to a ball mill, ground at 55 r / min for 5.5 h, passed through a 200 mesh sieve, and heated to 825° C. at a heating rate of 4° C. / min in an oxygen atmosphere and calcined for 20 h. The mixture is naturally cooled to room temperature, ground, and passed through a 325 mesh sieve to obtain a doped modified ternary positive electrode material. The remaining steps are the same as in Example 2.

[0068] Comparative Example 5:

[0069] The difference between the method for recycling and regenerating waste lithium battery positive electrode materials in Comparative Example 5 and Example 2 lies in the difference in step (4). Step (4) is modified as follows: 25 parts of ternary carbonate precursor, 7.91 parts of recovered lithium carbonate, 0.275 parts of lithium fluoride, and 3.56 parts of neodymium oxide are mixed uniformly by mass, added to a ball mill, ground at 55r / min for 5.5h, passed through a 200-mesh sieve, heated to 475°C at a heating rate of 4°C / min under an oxygen atmosphere, calcined for 4.5h, naturally cooled to room temperature, passed through a 200-mesh sieve after grinding, continued to heat to 825°C at a heating rate of 4°C / min under an oxygen atmosphere, calcined for 17h, naturally cooled to room temperature, and passed through a 325-mesh sieve after grinding to obtain a doped modified ternary positive electrode material. The remaining steps are the same as in Example 2.

[0070] Comparative Example 6:

[0071] The difference between the method for recycling and regenerating waste lithium battery positive electrode materials in Comparative Example 6 and Example 2 lies in the difference in step (4). Step (4) is modified as follows: 25 parts of ternary carbonate precursor, 7.91 parts of recovered lithium carbonate, and 0.275 parts of lithium fluoride are mixed uniformly by mass, added to a ball mill, ground at 55r / min for 5.5h, passed through a 200-mesh sieve, heated to 475°C at a heating rate of 4°C / min under an oxygen atmosphere, calcined for 4.5h, naturally cooled to room temperature, passed through a 200-mesh sieve after grinding, continued to heat to 825°C at a heating rate of 4°C / min under an oxygen atmosphere, calcined for 17h, naturally cooled to room temperature, and passed through a 325-mesh sieve after grinding to obtain a doped modified ternary positive electrode material. The remaining steps are the same as in Example 2.

[0072] Comparative Example 7:

[0073] The difference between the method for recycling and regenerating waste lithium battery positive electrode materials in Comparative Example 7 and Example 2 lies in the difference in step (4). Step (4) is modified as follows: 25 parts of ternary carbonate precursor and 8.3 parts of recovered lithium carbonate are mixed uniformly by mass, added to a ball mill, ground at 55r / min for 5.5h, passed through a 200-mesh sieve, heated to 475°C at a heating rate of 4°C / min under an oxygen atmosphere, calcined for 4.5h, naturally cooled to room temperature, passed through a 200-mesh sieve after grinding, and continued to heat to 825°C at a heating rate of 4°C / min under an oxygen atmosphere and calcined for 17h, naturally cooled to room temperature, and passed through a 325-mesh sieve after grinding to obtain a ternary positive electrode material. In step (5), the reaction raw material doped modified ternary positive electrode material is modified to a ternary positive electrode material. The remaining steps are the same as in Example 2.

[0074] Comparative Example 8:

[0075] The difference between the method for recycling and regenerating waste lithium battery positive electrode materials in Comparative Example 8 and Example 2 lies in the difference in step (5). Step (5) is modified as follows: 0.078 parts of zinc acetylacetonate, 0.097 parts of aluminum acetylacetonate, 3.5 parts of doped modified ternary positive electrode material, and 55 parts of ethylene glycol dimethyl ether are mixed uniformly by mass, ultrasonicated for 18 minutes, stirred at 1300r / min for 3.5 minutes under an argon atmosphere, 0.7 parts of potassium-sodium alloy are added, stirring is continued for 18 minutes, centrifuged at 9000rpm for 9 minutes, the solid is washed 3 times with ethylene glycol dimethyl ether, vacuum dried at 65°C for 7 hours, crushed and ground, passed through a 325-mesh sieve, heated to 825°C at a heating rate of 4°C / min under an air atmosphere, calcined for 4.5 hours, naturally cooled to room temperature, ground and passed through a 325-mesh sieve to obtain a coated modified ternary positive electrode material. The remaining steps are the same as in Example 2.

[0076] Comparative Example 9:

[0077] The difference between the method for recycling and regenerating waste lithium battery positive electrode materials in Comparative Example 9 and Example 2 is that step (5) is not performed. Step (5) is modified as follows: 0.175 parts of lanthanum acetylacetonate, 3.5 parts of doped modified ternary positive electrode material, and 55 parts of ethylene glycol dimethyl ether are mixed uniformly by mass, ultrasonicated for 18 minutes, stirred at 1300r / min for 3.5 minutes under an argon atmosphere, 0.7 parts of potassium-sodium alloy are added, stirring is continued for 18 minutes, centrifuged at 9000rpm for 9 minutes, the solid is washed 3 times with ethylene glycol dimethyl ether, vacuum dried at 65°C for 7 hours, crushed and ground, passed through a 325-mesh sieve, heated to 825°C at a heating rate of 4°C / min under an air atmosphere, calcined for 4.5 hours, naturally cooled to room temperature, ground and passed through a 325-mesh sieve to obtain a coated modified ternary positive electrode material. The remaining steps are the same as in Example 2.

[0078] Comparative Example 10:

[0079] The method for recycling and regenerating waste lithium battery positive electrode materials in Comparative Example 10 differs from that in Example 2 in that step (5) is omitted and step (6) is modified as follows: the doped modified ternary positive electrode material, the conductive agent, and the binder are uniformly mixed in a mass ratio of 8:1:1, poured into a ball mill, stirred for 12 minutes using a high-speed swing ball mill, 3.5 times the total mass of N-methylpyrrolidone is added, stirred at 350 r / min for 3.5 hours, and evenly applied to a carbon-coated aluminum foil. The mixture is vacuum-dried at 60° C. for 3.5 hours and then vacuum-dried at 120° C. for 11 hours to obtain a lithium battery positive electrode material. The remaining steps are the same as in Example 2.

[0080] The half-cell assembly method used in the subsequent test cases is as follows:

[0081] The prepared lithium battery positive electrode material was cut into a 10 mm diameter circular electrode with a flat edge using a punch. The remaining materials were assembled into button-type half-cells according to GB / T 43093-2023 for subsequent testing.

[0082] Test Example 1:

[0083] Initial charge and discharge capacity test: Use a current density of 0.1C for the initial charge and discharge capacity test, defining 1C as 200mAh / g, charge at a constant current to 4.8V, and discharge at a constant current to 2.5V, and record the data.

[0084] The results are shown in Table 1.

[0085] Table 1

[0086]

[0087]

[0088] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 10 in Table 1, it can be found that the lithium battery positive electrode material prepared by the present invention has a high charge and discharge specific capacity and good coulombic efficiency.

[0089] A comparison of the data in the table shows that the use of mixed reagents by adding all raw materials and the precipitant solution in parallel in the co-precipitation step effectively improves the charge-discharge specific capacity. Compared with step-by-step calcination and direct calcination, the secondary calcination can better improve the crystal structure of the material, thereby improving the charge-discharge specific capacity. At the same time, the co-doping of silicon, fluorine and neodymium also improves the charge-discharge specific capacity, improves the lithium ion diffusion efficiency, expands the lattice spacing, and suppresses the mixing of lithium and nickel, thereby improving the electrical performance.

[0090] Test Example 2:

[0091] Cycling performance test: Use a current density of 0.5C to test the cycling performance of the positive electrode material of the lithium battery. Define 1C as 200mAh / g, and cycle 2000 times at room temperature. Take the discharge specific capacity of the battery at a current density of 0.5C in Test Example 3 as a reference, record the discharge specific capacity and capacity retention rate after 2000 cycles, and record the data.

[0092] The results are shown in Table 2.

[0093] Table 2

[0094]

[0095]

[0096] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 10 in Table 2, it can be found that the lithium battery positive electrode material prepared by the present invention has a good cycle life.

[0097] By comparing the data in the table, it is shown that the use of mixed reagents by adding all raw materials and precipitant solution in parallel in the co-precipitation step effectively improves the crystal structure and growth shape, and effectively improves the cycle life. Compared with step-by-step calcination and direct calcination, the secondary calcination can better improve the crystal structure formation of the material, thereby improving the cycle life. The co-doping of silicon, fluorine and neodymium improves the lithium ion diffusion efficiency, expands the lattice spacing, and inhibits the mixing of lithium and nickel, thereby improving the cycle life. The presence of the composite coating effectively extends the cycle life by blocking the corrosion of the electrolyte on the positive electrode material and reducing the occurrence of side reactions.

[0098] Test Example 3:

[0099] Rate performance test: At room temperature, use current densities of 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, and 10C for 5 cycles respectively, defining 1C as 200mAh / g, to test the rate performance of the lithium battery positive electrode material and record the data.

[0100] The results are shown in Table 3.

[0101] Table 3

[0102]

[0103]

[0104] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 10 in Table 3, it can be found that the lithium battery positive electrode material prepared in the present invention has good rate performance.

[0105] A comparison of the data in the table shows that both doping modification and coating modification effectively improve the rate performance of lithium battery positive electrode materials. The coating layer improves the rate performance by increasing the electrical conductivity and reducing the interface impedance, while the doping modification improves the rate performance by maintaining the structural integrity. Both effectively improve the rate performance of the positive electrode material.

[0106] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A lithium battery positive electrode material, characterized in that The lithium battery positive electrode material is prepared by mixing the coated modified ternary positive electrode material with a conductive agent and a binder and then coating the mixture on a carbon-coated aluminum foil; The coated modified ternary positive electrode material is prepared by mixing lanthanum acetylacetonate, zinc acetylacetonate, aluminum acetylacetonate, and a doped modified ternary positive electrode material, shearing the mixture at high speed, adding potassium-sodium alloy for reduction, and then calcining the mixture. The doped modified ternary cathode material is prepared by mixing a ternary carbonate precursor, recycled lithium carbonate, silicon dioxide, lithium fluoride, and neodymium oxide, and then calcining the mixture twice; The lithium carbonate is recovered by disassembling the waste lithium iron phosphate battery after discharge, immersing the separated current collector in hot and cold water in a cycle, calcining it, and then selectively leaching the lithium ions with sulfuric acid-hydrogen peroxide for recovery; The ternary carbonate precursor is prepared by mixing a nickel source, a cobalt source and a manganese source to form a mixed salt solution, and then adding a precipitant solution under the complexation action of ammonia water to carry out co-precipitation.

2. A lithium battery positive electrode material according to claim 1, characterized in that: The nickel source is nickel sulfate heptahydrate; the cobalt source is cobalt sulfate hexahydrate; and the manganese source is manganese sulfate monohydrate.

3. A lithium battery positive electrode material according to claim 1, characterized in that: The mixed salt solution is prepared by dissolving a nickel source, a cobalt source, and a manganese source in pure water at a molar ratio of 6:2:2 to form a 2 mol / L mixed salt solution.

4. A lithium battery positive electrode material according to claim 1, characterized in that: The precipitant solution is prepared by mixing 1 mol / L sodium carbonate solution and 1 mol / L ammonium bicarbonate solution in a volume ratio of 1:

1.

5. A method for recycling and regenerating waste lithium battery positive electrode materials, characterized in that: The method comprises the following preparation steps: (1) After the waste lithium iron phosphate battery is discharged and inactivated, it is manually disassembled to separate the lithium iron phosphate positive electrode sheet, and the lithium iron phosphate positive electrode sheet is soaked in hot water and cold water in turn, each soaking for 2 to 3 minutes, and the soaking cycle is repeated until the current collector is detached to obtain a lithium iron phosphate positive electrode material, and dimethylformamide is added to the lithium iron phosphate positive electrode material at a liquid-solid ratio of 3:1 g / g and mixed evenly, and calcined at 450 to 500 ° C for 2 to 3 hours under an argon atmosphere, cooled naturally to room temperature, crushed and ground, and passed through a 100 mesh sieve to obtain a lithium iron phosphate positive electrode material powder; (2) By weight, 2 to 3 parts of lithium iron phosphate positive electrode material powder, 4 to 6 parts of hydrogen peroxide, 16 to 24 parts of 0.4 mol / L sulfuric acid solution, and 80 to 120 parts of pure water were mixed evenly, stirred at 68 to 72 ° C and 250 to 350 r / min for 30 to 40 minutes, filtered, and the residue was separated for iron recovery. The filtrate was concentrated to a lithium ion concentration of 30 g / L, and the pH was adjusted to 10 with sodium hydroxide solution. Saturated sodium carbonate solution was added at 90 ° C and 300 to 400 r / min at a sodium carbonate to lithium ion molar ratio of (1.2 to 1.4):

1. After the addition was completed, stirring was continued for 60 to 80 minutes, filtered, washed with boiling pure water for 3 to 4 times, and vacuum dried at 70 to 80 ° C for 10 to 12 hours to obtain recovered lithium carbonate; (3) First, add 20-30 parts of pure water by mass, then add 40-50 parts of mixed salt solution, 20-30 parts of ammonia water, and 50-60 parts of precipitant solution at 60-70°C and 500-600 r / min. The flow rate ratio of the mixed salt solution and ammonia solution is controlled to be 2:1, and the flow rate of the precipitant solution is controlled to control the pH value at 7.5-8. After all the solution is added, the reaction is carried out for 8-10 hours, and stirring is stopped. After sealing, the solution is aged in a water bath at 60-70° C. for 12-14 hours, filtered, washed with pure water until the pH value is less than 7.5, vacuum dried at 60-70° C. for 6-8 hours, crushed and ground, and passed through a 120-mesh sieve to obtain a ternary carbonate precursor. (4) According to the mass ratio, 20 to 30 parts of carbonate ternary precursor, 6.39 to 9.39 parts of recovered lithium carbonate, 0.075 to 0.112 parts of silicon dioxide, 0.176 to 0.396 parts of lithium fluoride, and 2.85 to 4.28 parts of neodymium oxide are mixed evenly, added to a ball mill, ground at 50 to 60 r / min for 5 to 6 hours, passed through a 200 mesh sieve, heated to 450 to 500 ° C at a heating rate of 3 to 4 ° C / min in an oxygen atmosphere, calcined for 4 to 5 hours, cooled naturally to room temperature, and passed through a 200 mesh sieve after grinding. In an oxygen atmosphere, the temperature is continuously increased to 800 to 850 ° C at a heating rate of 3 to 4 ° C / min and calcined for 16 to 18 hours, cooled naturally to room temperature, and passed through a 325 mesh sieve after grinding to obtain a doped modified ternary positive electrode material; (5) By weight, 0.064-0.085 parts of lanthanum acetylacetonate, 0.039-0.051 parts of zinc acetylacetonate, 0.048-0.063 parts of aluminum acetylacetonate, 3-4 parts of doped modified ternary cathode material, and 50-60 parts of ethylene glycol dimethyl ether were mixed uniformly, ultrasonicated for 15-20 minutes, stirred at 1200-1400 r / min for 3-4 minutes under an argon atmosphere, and 0.6-0.8 parts of potassium-sodium alloy were added. , continue stirring for 15 to 20 minutes, centrifuge at 8000 to 10000 rpm for 8 to 10 minutes, wash the solid with ethylene glycol dimethyl ether 2 to 3 times, vacuum dry at 60 to 70 ° C for 6 to 8 hours, crush and grind, pass through a 325 mesh sieve, and heat to 800 to 850 ° C at a heating rate of 3 to 4 ° C / min in an air atmosphere and calcine for 4 to 5 hours, cool naturally to room temperature, grind and pass through a 325 mesh sieve to obtain a coated modified ternary positive electrode material; (6) The coated modified ternary positive electrode material, conductive agent and binder are mixed evenly in a mass ratio of 8:1:1, poured into a ball mill, stirred for 10 to 15 minutes using a high-speed swing ball mill, and 3.5 times the total mass of N-methylpyrrolidone is added. The mixture is stirred at 300 to 400 r / min for 3 to 4 hours, evenly applied on a carbon-coated aluminum foil, and vacuum dried at 60°C for 3 to 4 hours, and then vacuum dried at 120°C for 10 to 12 hours to obtain a lithium battery positive electrode material.

6. The method for recycling cathode materials of waste lithium batteries according to claim 5, characterized in that: The hot water in step (1) is 80-90°C, and the cold water is 10-20°C.

7. The method for recycling cathode materials of waste lithium batteries according to claim 5, characterized in that: The concentration of the hydrogen peroxide in step (2) is 30wt%.

8. The method for recycling cathode materials of waste lithium batteries according to claim 5, characterized in that: The ammonia concentration in step (3) is 1 mol / L.

9. The method for recycling cathode materials of waste lithium batteries according to claim 5, characterized in that: The mass ratio of potassium to sodium in the potassium-sodium alloy in step (5) is 3:

1.

10. The method for recycling cathode materials of waste lithium batteries according to claim 5, characterized in that: The conductive agent in step (6) is acetylene black, and the median diameter is 1 to 3 μm.

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