Regeneration method of waste lithium battery positive electrode material

Abstract

The invention relates to the field of new energy batteries, in particular to a regeneration method of a waste lithium battery positive electrode material, which comprises the following steps: S1, mixing positive electrode waste powder of a ternary lithium ion battery with ammonium salt to obtain a first mixture, and roasting the first mixture to obtain a first material; s2, mixing the first material with a first solvent, and performing atomization treatment to obtain liquid drops; carrying out spray pyrolysis treatment on the liquid drops to obtain pyrolysis powder; washing and filtering the pyrolysis powder to obtain a ternary oxide precursor and a Li-containing solution; s3, the Li-containing solution and the Na2CO3 saturated solution are subjected to mixing treatment, and Li2CO3 powder is obtained; and S4, the ternary oxide precursor and Li2CO3 powder are mixed and then subjected to calcination treatment, a ternary finished product LiNi < x > Co < y > Mn < z > O < 2 > is obtained, and x + y + z = 1. According to the process, other chemical reagents do not need to be added, and pollution can be greatly avoided; and meanwhile, by using the chloride pyrolysis temperature difference, the target product can be directly extracted.

Description

Technical Field

[0001] The present invention relates to the field of new energy batteries, and in particular to a method for regenerating positive electrode materials of waste lithium batteries. Background Art

[0002] Considering the limited lifespan of electric vehicle batteries, the foreseeable large number of scrapped battery packs in the near future will cause concerns about the disposal of waste batteries. In a typical lithium-ion battery, the positive electrode material accounts for about 40% of the material cost and represents the highest recycling value. At the same time, the recycling and reuse of waste lithium-ion batteries has become one of the urgent problems to be solved today. If left at random, it will not only waste valuable metals, but also pollute the environment with harmful substances. Therefore, the recycling and reuse of waste lithium ions has become a hot topic of research.

[0003] At present, there are two methods for recycling waste lithium batteries. The first is the pyrometallurgical process: this method mainly extracts and refines the target metal from minerals through high-temperature smelting and reduction reactions. In the pyrometallurgical process of failed ternary lithium-ion batteries, the valuable metals in the battery are reduced at high temperatures and then recovered in the form of alloys. This is a popular method mainly abroad. However, the pyrometallurgical process will produce a lot of dust and CO, CO2. And it is difficult to effectively recover the valuable metal element lithium, so it is not cost-effective for process production.

[0004] The second process is wet process recovery. The wet metallurgical process mainly includes the leaching process of active materials and the separation of valuable metals from the leachate to prepare the corresponding products. Although this process is mature, there are still many problems. For example, impurities such as aluminum and iron enter the leachate during acid leaching, and the solution impurity removal process is complicated; the solvent extraction separation of manganese, cobalt, and nickel has a long process and many stages; sulfuric acid leaching, solution purification (alkaline neutralization to remove iron and aluminum) and solvent extraction (extractant alkali saponification, sulfuric acid stripping) consume twice the molar amount of sulfuric acid and twice the molar amount of sodium hydroxide or ammonia of the valuable metal, and the consumption of chemical reagents is large.

[0005] Therefore, developing a method that can directly repair the crystal structure of NCM positive electrode materials through reduction while ensuring the high purity and high consistency of the material is an urgent problem to be solved. Summary of the invention

[0006] In view of this, the present invention is committed to providing a method for regenerating waste lithium battery positive electrode materials to solve the problems in the prior art that the crystal structure of NCM positive electrode materials cannot be directly repaired by reduction, and the high purity and high consistency of positive electrode regenerated materials cannot be guaranteed.

[0007] In order to solve the above technical problems, this application is implemented as follows:

[0008] A first aspect of the present invention provides a method for regenerating anode materials of waste lithium batteries, the method comprising the following steps:

[0009] S1. Mixing the cathode waste powder of the ternary lithium-ion battery with an ammonium salt to obtain a first mixture, and calcining the first mixture to obtain a first material;

[0010] S2, mixing the first material with the first solvent and then atomizing the mixture to obtain droplets; spraying the droplets to obtain pyrolysis powder; washing and filtering the pyrolysis powder to obtain a ternary oxide precursor and a Li-containing solution;

[0011] S3, mixing the Li-containing solution with a saturated Na2CO3 solution to obtain Li2CO3 powder;

[0012] S4, mixing the ternary oxide precursor with the Li2CO3 powder and calcining the mixture to obtain a ternary finished product LiNi x Co y Mn z O2, where x+y+z=1.

[0013] Optionally, in step S1, the mass ratio of the positive electrode waste powder of the ternary lithium-ion battery and the ammonium salt is 1:(1-5); the ammonium salt is selected from NH4Cl and / or NH4SO4; preferably, the ammonium salt is selected from NH4Cl; and the first solvent is water.

[0014] Optionally, in step S4, the mass ratio of the ternary oxide precursor to the Li2CO3 powder is 1:(0.98-1.05).

[0015] Optionally, in step S1, the calcination treatment is carried out in a first oxygen-containing atmosphere; the conditions of the calcination treatment include: a temperature of 200-800°C and a time of 10-40 min; preferably, the conditions of the calcination treatment include: a temperature of 300-600°C and a time of 30-40 min.

[0016] Optionally, in step S2, the spray pyrolysis treatment includes: passing a gas-liquid mixture of the droplets and the pyrolysis gas into a reactor for pyrolysis, and collecting the pyrolysis powder at the reactor outlet; the pyrolysis gas is a second oxygen-containing atmosphere; preferably, the second oxygen-containing atmosphere is air; the flow rate of the gas-liquid mixture into the reactor is 8 to 12 L / min, and the pyrolysis temperature is 500 to 850°C; preferably, the flow rate of the gas-liquid mixture into the reactor is 10 to 12 L / min, and the pyrolysis temperature is 600 to 750°C.

[0017] Optionally, in step S3, the mixing treatment includes dropping the Na2CO3 saturated solution into the Li-containing solution; wherein the temperature of the mixing treatment is 80-100°C.

[0018] Optionally, in step S4, the calcination treatment is carried out in an oxygen-containing atmosphere, preferably, the oxygen-containing atmosphere is an oxygen atmosphere or an air atmosphere; the conditions of the calcination treatment include: a temperature of 550 to 650° C. and a time of 4 to 6 hours.

[0019] Optionally, the regeneration method further comprises:

[0020] Soaking the used ternary lithium-ion batteries in a conductive liquid to obtain used batteries;

[0021] Disassembling the waste batteries to obtain waste positive electrode sheets;

[0022] After washing the waste positive electrode plates with an organic solvent, the powder of the waste positive electrode plates is collected to obtain positive electrode waste powder.

[0023] Optionally, the immersion time is 48 to 72 hours; the conductive liquid is selected from at least one of NaCl solution, KOH solution, Na2CO3 solution and NaOH solution; preferably, the conductive liquid is NaCl solution, and the mass fraction of NaCl in the NaCl solution is 10 to 20wt%; the organic solvent includes dimethyl carbonate.

[0024] A second aspect of the present invention provides a positive electrode material, which is prepared according to the above-mentioned regeneration method.

[0025] Through the above technical solution, the beneficial technical effects of the present invention are:

[0026] (1) The present invention successfully applies the spray pyrolysis process to the recovery of positive electrode materials of ternary lithium-ion batteries, and can simultaneously achieve the selective extraction of Li elements and the synthesis of ternary oxide precursors. The present invention obtains LiCl solution and ternary oxide precursors from the positive electrode waste powder of ternary lithium-ion batteries through chlorination roasting, spray pyrolysis, and water leaching, which can be directly used to prepare battery-grade Li2CO3 and NCM positive electrodes. At the same time, the additional roasting process can effectively remove the residual Cl in the spray pyrolysis powder and achieve deep separation of Li and TMs (transition metal elements). Compared with the traditional solution of directly removing TMs from the leaching solution, the additional roasting process can maintain the target ratio of TMs in the ternary oxide and produce the required ternary precursor.

[0027] (2) The present invention can extract all metal ions in waste NCM powder through the chlorination conversion process. Subsequently, the chlorine solution is converted into LiCl and ternary oxides through a spray pyrolysis process; the process of the present invention does not require the addition of other chemical reagents, which can greatly avoid pollution; at the same time, the present invention uses the temperature difference of chloride pyrolysis to directly extract the target product.

[0028] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0030] Figure 1 Shown is a curve chart of the long cycle test of the batteries prepared in Examples 1 to 3 at 25°C. DETAILED DESCRIPTION

[0031] The present invention discloses a method for regenerating anode materials of waste lithium batteries. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve the method. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in the present invention. The method and application of the present invention have been described through preferred embodiments. It is obvious that relevant personnel can modify or appropriately change and combine the method and application described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0032] In the description of the present invention, a list of items connected by the term "at least one of" or other similar terms may mean any combination of the listed items. For example, if items A, B are listed, the phrase "at least one of A, B" means only A; only B; or A and B. In another example, if items A, B, C are listed, the phrase "at least one of A, B, C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may include a single element or multiple elements. Item B may include a single element or multiple elements. Item C may include a single element or multiple elements.

[0033] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range or the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0034] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0035] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0036] If there is no special explanation, the "include" and "comprising" mentioned in this application represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0037] In order to solve the problem that the crystal structure of NCM positive electrode materials cannot be directly repaired by reduction in the prior art, and the high purity and high consistency of positive electrode recycled materials cannot be guaranteed, the present invention adopts the following technical solution:

[0038] A first aspect of the present invention provides a method for regenerating anode materials of waste lithium batteries, the method comprising the following steps:

[0039] S1. Mixing the cathode waste powder of the ternary lithium-ion battery with an ammonium salt to obtain a first mixture, and calcining the first mixture to obtain a first material;

[0040] S2, mixing the first material with the first solvent and then atomizing the mixture to obtain droplets; spraying the droplets to obtain pyrolysis powder; washing and filtering the pyrolysis powder to obtain a ternary oxide precursor and a Li-containing solution;

[0041] S3, mixing the Li-containing solution with a saturated Na2CO3 solution to obtain Li2CO3 powder;

[0042] S4, mixing the ternary oxide precursor with the Li2CO3 powder and calcining the mixture to obtain a ternary finished product LiNi x Co y Mn z O2, where x+y+z=1.

[0043] The present invention successfully applies the spray pyrolysis process to the recovery of positive electrode materials of ternary lithium-ion batteries, and can simultaneously realize the selective extraction of Li elements and the synthesis of ternary oxide precursors. The present invention obtains LiCl solution and ternary oxide precursors (mainly composed of transition metal oxides, such as NiO, MnO2, Co3O4, NiO2, etc.) by chlorination roasting, spray pyrolysis, and water immersion of positive electrode waste powder of ternary lithium-ion batteries. a CO b Mnc O2 and other two or three transition metal composite oxides, where 0<a<1, 0<b<1, 0<c<1), can be directly used to prepare battery-grade Li2CO3 and NCM positive electrodes. At the same time, the additional roasting process can effectively remove the residual Cl in the spray pyrolysis powder and achieve deep separation of Li and TMs (transition metal elements). Compared with the traditional solution of directly removing TMs from the leaching solution, the additional roasting process can maintain the target ratio of TMs in the ternary oxide and produce the required ternary precursor.

[0044] According to the present invention, in step S1, the ammonium salt can provide an alkaline environment on the one hand, and can form a soluble metal salt with the metal elements in the positive electrode waste powder on the other hand. The mass ratio of the positive electrode waste powder of the ternary lithium-ion battery and the ammonium salt can be 1: (1 to 5); illustratively, the mass ratio of the positive electrode waste powder of the ternary lithium-ion battery and the ammonium salt can be any of 1:1, 1:2, 1:3, 1:4 and 1:5 or any value within the range of any two of the above values. The ammonium salt used in the present invention can be selected from NH4Cl and / or NH4SO4; preferably, the ammonium salt can be selected from NH4Cl. The reaction occurring in this step is shown as follows:

[0045] 6LiTMO2+18NH4Cl→6TMCl2+6LiCl+N2+16NH3↑+12H2O (where TM is a transition metal element).

[0046] Illustratively, the first solvent used in the present invention may be water.

[0047] In step S4 of the present invention, since the product reactant is a recycled material and the specific product form is to be determined, the mass ratio of the ternary oxide precursor to the Li2CO3 powder can be 1:(0.98-1.05). Exemplarily, the mass ratio of the ternary oxide precursor to the Li2CO3 powder can be any value among 1:0.98, 1:0.99, 1:1, 1:1.01, 1:1.02, 1:1.03, 1:1.04 and 1:1.05 or any value within the range of any two of the above values. In one embodiment, a slightly excess of Li2CO3 powder can be used, and a slightly excess of Li2CO3 powder can ensure that the reaction is fully carried out.

[0048] According to the present invention, in step S1, the calcination treatment is carried out in a first oxygen-containing atmosphere; preferably, the first oxygen-containing atmosphere can be air; the conditions for the calcination treatment may include: a temperature of 200 to 800°C and a time of 10 to 40 minutes; preferably, the conditions for the calcination treatment may include: a temperature of 300 to 600°C and a time of 30 to 40 minutes.

[0049] According to the present invention, in step S2, the spray pyrolysis treatment may include: passing the gas-liquid mixture of the droplets and the pyrolysis gas into the reactor for pyrolysis, and collecting the pyrolysis powder at the outlet of the reactor; the pyrolysis gas may be a second oxygen-containing atmosphere; preferably, the second oxygen-containing atmosphere may be air; the flow rate of the gas-liquid mixture into the reactor may be 8 to 12 L / min. In the present invention, the spontaneous decomposition starting temperature of TMCl2 contained in the system in step S2 is about 200-250°C, and the spontaneous decomposition starting temperature of LiCl is greater than or equal to 1000°C, so the pyrolysis temperature in the present invention may be 500 to 850°C, at which temperature TMCl2 can be converted into TM oxide; preferably, the flow rate of the gas-liquid mixture into the reactor may be 10 to 12 L / min, and the pyrolysis temperature may be 600 to 750°C.

[0050] According to the present invention, in step S3, the mixing treatment may include dripping the Na2CO3 saturated solution into the Li-containing solution; in order to facilitate the precipitation of Li2CO3 powder, the temperature of the mixing treatment may be 80-100°C.

[0051] According to the present invention, in step S4, the calcination treatment is carried out in an oxygen-containing atmosphere, preferably, the oxygen-containing atmosphere is an oxygen atmosphere or an air atmosphere; the conditions of the calcination treatment may include: a temperature of 550 to 650° C. and a time of 4 to 6 hours.

[0052] In one embodiment of the present invention, the regeneration method may further include:

[0053] Soaking the used ternary lithium-ion batteries in a conductive liquid to obtain used batteries;

[0054] Disassembling the waste batteries to obtain waste positive electrode sheets;

[0055] After washing the waste positive electrode plates with an organic solvent, the powder of the waste positive electrode plates is collected to obtain positive electrode waste powder.

[0056] According to the present invention, the immersion time can be 48 to 72 hours; the conductive liquid can be selected from at least one of NaCl solution, KOH solution, Na2CO3 solution and NaOH solution; preferably, the conductive liquid can be a NaCl solution, and the mass fraction of NaCl in the NaCl solution can be 10 to 20wt%; the organic solvent can include dimethyl carbonate.

[0057] In another embodiment of the present invention, the regeneration method further comprises taking out a powder collector from the reaction device to collect powder every 30 to 60 minutes (powder can easily fall off the nickel foam), and then the nickel foam can be reused to collect powder again.

[0058] A second aspect of the present invention provides a positive electrode material, which is prepared according to the above-mentioned regeneration method.

[0059] The present invention is further described in detail by way of examples. The raw materials used in the examples can be obtained through commercial sources.

[0060] Example 1

[0061] The positive electrode of the waste lithium-ion battery used in this embodiment is NCM 811 (Li 1.02 Ni 0.8 Co 0.1 Mn 0.1 O2).

[0062] The method for regenerating the positive electrode material of waste lithium batteries in this embodiment includes:

[0063] (1) The used lithium-ion battery was discharged in a 15% NaCl solution for 50 hours and then disassembled by physical methods in a fume hood. After the core was removed, the core was disassembled and the cathode electrode was immediately rinsed with dimethyl carbonate for 3 times to remove the residual electrolyte to obtain the positive electrode. The obtained positive electrode was placed in an ultrasonic instrument containing an aqueous solution and an 85KHz ultrasonic resonance was added for 5 hours to separate the positive electrode material from the aluminum foil and extract the positive electrode waste powder.

[0064] (2) The positive electrode waste powder and NH4Cl are mixed in a molar ratio of 1:2 to obtain a first mixture, and then the first mixture is calcined in air to obtain a first material, wherein the calcination temperature is 400° C. and the time is 30 min.

[0065] (3) The first material was dissolved in distilled water at room temperature, and the leaching solution was atomized using a 1.75 MHz ultrasonic atomizer to obtain droplets. The droplet flow rate was 10 L min -1 The spray pyrolysis temperature is maintained between 650 and 800°C, and the pyrolysis powder is collected at the reactor outlet using nickel foam as a collector. The powder is washed, filtered, and dried using a water immersion method to obtain a ternary oxide precursor and a LiCl solution.

[0066] (4) Add saturated Na2CO3 solution into LiCl solution to precipitate lithium source in the form of Li2CO3 at 95°C.

[0067] (5) The ternary oxide precursor powder was fully mixed with the recovered Li2CO3 and calcined at 650°C for 8h to obtain the regenerated positive electrode material of this embodiment.

[0068] Example 2

[0069] The positive electrode of the waste lithium-ion battery used in this embodiment is NCM 811 (Li 1.02 Ni 0.8 Co 0.1 Mn 0.1 O2).

[0070] The method for regenerating waste lithium battery positive electrode materials in this embodiment is generally the same as that in Embodiment 1, except that in step (2), waste NCM powder and NH4Cl are mixed in a molar ratio of 1:3.

[0071] Example 3

[0072] The positive electrode of the waste lithium-ion battery used in this embodiment is NCM 811 (Li 1.02 Ni 0.8 Co 0.1 Mn 0.1 O2).

[0073] The method for regenerating the positive electrode material of waste lithium batteries in this embodiment is generally the same as that in Embodiment 1, except that in step (2), the waste NCM powder is mixed with NH4Cl in a molar ratio of 1:4.

[0074] Example 4

[0075] The positive electrode of the waste lithium-ion battery used in this embodiment is NCM 523 (Li 1.02 Ni 0.5 Co 0.2 Mn 0.3 O2).

[0076] The method for regenerating waste lithium battery positive electrode materials in this embodiment is generally the same as that in Embodiment 1, except that in step (2), waste NCM powder and NH4Cl are mixed in a molar ratio of 1:3.

[0077] Example 5 (NCM 613)

[0078] The positive electrode of the waste lithium-ion battery used in this embodiment is NCM 613 (Li 1.02 Ni 0.6 Co 0.1 Mn 0.3 O2).

[0079] The method for regenerating waste lithium battery positive electrode materials in this embodiment is generally the same as that in Embodiment 1, except that in step (2), waste NCM powder and NH4Cl are mixed in a molar ratio of 1:3.

[0080] Example 6

[0081] The positive electrode of the waste lithium-ion battery used in this embodiment is NCM 712 (Li 1.02 Ni 0.7 Co 0.1 Mn 0.2 O2).

[0082] The method for regenerating waste lithium battery positive electrode materials in this embodiment is generally the same as that in Embodiment 1, except that in step (2), waste NCM powder and NH4Cl are mixed in a molar ratio of 1:3.

[0083] Example 7

[0084] The positive electrode of the waste lithium-ion battery used in this embodiment is NCM 920206 (Li 1.02 Ni 0.92 Co 0.02 Mn 0.06 O2).

[0085] The method for regenerating waste lithium battery positive electrode materials in this embodiment is generally the same as that in Embodiment 1, except that in step (2), waste NCM powder and NH4Cl are mixed in a molar ratio of 1:3.

[0086] Comparative Example 1

[0087] The positive electrode of the waste lithium-ion battery used in this embodiment is NCM 811 (Li 1.02 Ni 0.8 Co 0.1 Mn 0.1 O2).

[0088] The method for regenerating the positive electrode material of waste lithium batteries in this embodiment includes:

[0089] (1) The used lithium-ion battery was discharged in a 15% NaCl solution for 50 hours and then disassembled by physical methods in a fume hood. After the core was removed, the core was disassembled and the cathode electrode was immediately rinsed with dimethyl carbonate for 3 times to remove the residual electrolyte to obtain the positive electrode. The obtained positive electrode was placed in an ultrasonic instrument containing an aqueous solution and an 85KHz ultrasonic resonance was added for 5 hours to separate the positive electrode material from the aluminum foil and extract the positive electrode waste powder.

[0090] (2) Weigh 1 g of positive electrode waste powder, add 0.02 mol of lithium hydroxide, 0.03 mol of lithium nitrate, 0.004 mol of sodium sulfate, 0.05 g of manganese dioxide and 0.05 g of cobalt oxide, grind and mix; after mixing evenly, perform a two-stage heat treatment of low temperature and high temperature, firstly heat the mixture to 200°C at a heating rate of 5°C / min in an oxygen atmosphere, keep the temperature for 6 h, then continue to heat the mixture to 780°C at a heating rate of 5°C / min, keep the temperature for 6 h, and then cool the mixture with the furnace to obtain an intermediate product;

[0091] (3) The intermediate product was washed and filtered three times, and the obtained filter residue was dried at 80°C for 10 h, and annealed after adding 3 wt% lithium hydroxide. The temperature was increased to 700°C at a heating rate of 5°C / min in an oxygen atmosphere and kept at this temperature for 6 h to obtain the regenerated positive electrode material of this comparative example.

[0092] Test Example 1

[0093] The regenerated positive electrode materials prepared in Examples 1 to 7 and Comparative Example 1 were used to prepare batteries, and the performance of the prepared batteries was tested.

[0094] The method for preparing the battery comprises:

[0095] The positive electrode material, polyvinylidene fluoride and acetylene black were mixed in a mass ratio of 92:6:4 to prepare the positive electrode slurry. The obtained positive electrode slurry was coated on aluminum cloth, and after drying and rolling, the obtained positive electrode sheet was punched to obtain a disc with a diameter of 1.2 cm. The items required for the experiment were placed in an oven at 60°C for 12 hours of drying. Subsequently, the CR2032 button battery was assembled in an argon-protected glove box, in which the negative electrode was a purchased metal lithium sheet and the electrolyte was a mixed solution of 1 mol / L LiPF6 dissolved in ethylene carbonate (EC) / dimethyl carbonate (DEC) / ethyl methyl carbonate (EMC) (volume ratio of 1:1:1). The battery assembly order is negative electrode shell-metal lithium-diaphragm-positive electrode sheet-gasket-spring-positive electrode shell. The assembled battery was subjected to a power-on test under the following test conditions: LR 2032, 0.1C, 2.5-4.3V, vs. Li+ / Li. The charging and discharging equipment used was a Blue Power charging and discharging instrument.

[0096] The battery prepared in Examples 1 to 3 was subjected to a capacity decay test under long cycles. The test method is as follows: 5°C cycle performance test: First, in an environment of 25°C, the first charge and discharge were performed. After constant current charging at a charging current of 1C to a voltage of 4.25V (according to the voltage in the embodiment), the charging cutoff current was 0.05C at a constant voltage of 4.25V. After standing for 15 minutes, constant current discharge was performed at a discharge current of 1C to 2.8V. The discharge capacity of the first cycle was recorded as C1; then the charge and discharge cycle was performed until the capacity decayed to 80% of C1. The test results are shown in Figure 1 .

[0097] The batteries prepared in Examples 1 to 7 and Comparative Example 1 were subjected to a 0.3C discharge capacity test, a first coulombic efficiency test, and an average voltage platform test. The test results are shown in Table 1.

[0098] The test method of 0.3C discharge capacity includes: at 25°C, the lithium-ion battery is allowed to stand for 30 minutes, charged at a constant current of 0.3C to a voltage of 4.25V (according to the voltage in the embodiment), then charged at a constant voltage to a current ≤0.05C, and then allowed to stand for 15 minutes, discharged at a constant current of 0.3C to 2.8V, and the first cycle charge and discharge capacity is recorded, and the discharge specific capacity is calculated according to the weight of the positive electrode sheet, and the discharge specific capacity = discharge capacity / mass of positive electrode active material.

[0099] The test method of the first coulombic efficiency includes: in the 0.3C discharge capacity test, the first charging capacity and the discharge capacity are recorded simultaneously, and the first coulombic efficiency = discharge capacity / charge capacity.

[0100] The test method of the average voltage platform includes: in a 0.3C discharge capacity test, the discharge energy and the discharge capacity are recorded simultaneously, and the average voltage platform = discharge energy / discharge capacity.

[0101] Table 1

[0102]

[0103] It can be seen from the data in Table 1 that compared with Example 1, Examples 2 to 3 change the ratio of waste NCM powder to NH4Cl, and change the leaching efficiency of the Li element by controlling the amount of NH4Cl added. The appropriate mixing ratio of waste NCM powder and NH4Cl can improve the 0.3C discharge capacity, the first coulomb efficiency and the voltage platform. Examples 4 to 7 discuss the recovery effect of the present invention on several other ternary materials in the case of different proportions of ternary materials on the market. After comparison, it was found that with the increase of the Mn ratio, the lower the leaching efficiency of Li, it may be because the formation of the layered structure cathode affects the embedding depth of Li in the TM (Ni, Co, Mn) layered oxide. Tm oxide is not easy to be recovered because it is easy to react with exhaust gas (HCl, H2O) when passing through the reactor outlet. Comparative Example 1 did not use the process of the present invention, and the 0.3C discharge capacity, the first coulomb efficiency and the voltage platform were significantly reduced.

[0104] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for regenerating anode materials of waste lithium batteries, characterized in that: The method comprises the following steps: S1. Mixing the cathode waste powder of the ternary lithium-ion battery with an ammonium salt to obtain a first mixture, and calcining the first mixture to obtain a first material; S2, mixing the first material with the first solvent and then atomizing the mixture to obtain droplets; spraying the droplets to obtain pyrolysis powder; washing and filtering the pyrolysis powder to obtain a ternary oxide precursor and a Li-containing solution; S3, mixing the Li-containing solution with a saturated Na2CO3 solution to obtain Li2CO3 powder; S4, mixing the ternary oxide precursor with the Li2CO3 powder and calcining the mixture to obtain a ternary finished product LiNi x Co y Mn z O2, where x+y+z=1.

2. The regeneration method according to claim 1, characterized in that: In step S1, the mass ratio of the positive electrode waste powder of the ternary lithium-ion battery to the ammonium salt is 1:(1-5); The ammonium salt is selected from NH4Cl and / or NH4SO4; preferably, the ammonium salt is selected from NH4Cl; The first solvent is water.

3. The regeneration method according to claim 1, characterized in that: In step S4, the mass ratio of the ternary oxide precursor to the Li2CO3 powder is 1:(0.98-1.05).

4. The regeneration method according to claim 1, characterized in that: In step S1, the calcination treatment is performed in a first oxygen-containing atmosphere; the calcination treatment conditions include: a temperature of 200 to 800° C. and a time of 10 to 40 minutes; Preferably, the calcination treatment conditions include: a temperature of 300 to 600° C. and a time of 30 to 40 minutes.

5. The regeneration method according to claim 1, characterized in that: In step S2, the spray pyrolysis treatment includes: passing the gas-liquid mixture of the liquid droplets and the pyrolysis gas into a reactor for pyrolysis, and collecting the pyrolysis powder at the reactor outlet; The pyrolysis gas is a second oxygen-containing atmosphere; preferably, the second oxygen-containing atmosphere is air; The flow rate of the gas-liquid mixture into the reactor is 8-12 L / min, and the pyrolysis temperature is 500-850°C; preferably, the flow rate of the gas-liquid mixture into the reactor is 10-12 L / min, and the pyrolysis temperature is 600-750°C.

6. The regeneration method according to claim 1, characterized in that: In step S3, the mixing treatment includes dropping the Na2CO3 saturated solution into the Li-containing solution; wherein the temperature of the mixing treatment is 80-100°C.

7. The regeneration method according to claim 1, characterized in that: In step S4, the calcination treatment is carried out in an oxygen-containing atmosphere, preferably, the oxygen-containing atmosphere is an oxygen atmosphere or an air atmosphere; the conditions of the calcination treatment include: a temperature of 550 to 650° C. and a time of 4 to 6 hours.

8. The regeneration method according to claim 1, characterized in that: The regeneration method further comprises: Soaking the used ternary lithium-ion batteries in a conductive liquid to obtain used batteries; Disassembling the waste batteries to obtain waste positive electrode sheets; After washing the waste positive electrode plates with an organic solvent, the powder of the waste positive electrode plates is collected to obtain positive electrode waste powder.

9. The regeneration method according to claim 8, characterized in that: The soaking time is 48 to 72 hours; The conductive liquid is selected from at least one of a NaCl solution, a KOH solution, a Na2CO3 solution and a NaOH solution; preferably, the conductive liquid is a NaCl solution, and the mass fraction of NaCl in the NaCl solution is 10-20wt%; The organic solvent includes dimethyl carbonate.

10. A positive electrode material, characterized in that: The positive electrode material is prepared according to the regeneration method according to any one of claims 1 to 9.

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