Method for recycling waste ternary positive electrode material, doped ternary material and lithium ion battery

Abstract

The invention relates to the technical field of lithium ion battery recovery, and discloses a method for recovering a ternary positive electrode material, a doped ternary material and a lithium ion battery. The invention provides a method for recycling a waste ternary positive electrode material, which comprises the following steps: mixing and roasting a waste ternary material and an inorganic base to obtain a ternary material mixture, the waste ternary material comprising a fluorine-containing material; and carrying out oxygen-enriched roasting treatment on the ternary material mixture to obtain the doped ternary material. According to the method, the waste ternary material can be efficiently recycled, and the fluorine-containing material in the waste ternary material is effectively utilized as a resource. Through a fluorine element doping means, the doped ternary material is prepared in a ternary material crystal structure remodeling process.

Description

Technical Field

[0001] This application relates to the technical field of lithium-ion battery recycling, and specifically, to methods for recycling waste ternary cathode materials, doped ternary materials, and lithium-ion batteries. Background Art

[0002] As one of the most promising technologies in the new energy field in the 21st century, lithium-ion batteries are widely used in power batteries and energy storage power supplies. During the production process of lithium-ion batteries, a large amount of waste is generated. These wastes, as solid wastes, pose an environmental risk that cannot be ignored, and at the same time, they also have considerable recycling value. For example, the waste of lithium-ion batteries contains a large amount of valuable metals, and the metal grade is much higher than that of primary ores. In order to reduce the waste of valuable metals and avoid the impact of simple landfill of solid wastes on the environment and human health, it is beneficial to standardize the collection of lithium-ion battery-related wastes and efficiently utilize these substances, and develop their recycling value, which is conducive to achieving a win-win situation of ecological value and economic value. Summary of the Invention

[0003] In a first aspect of the present application, a method for recycling waste ternary cathode materials is proposed, including: performing a mixed roasting treatment on the waste ternary material and an inorganic base to obtain a ternary material mixture, wherein the waste ternary material includes a fluorine-containing material; performing an oxygen-enriched roasting treatment on the ternary material mixture to obtain a doped ternary material.

[0004] Thus, this method can efficiently recycle waste ternary materials and effectively utilize the fluorine-containing materials in the waste ternary materials as resources. By means of fluorine element doping, a doped ternary material is prepared during the process of reshaping the crystal structure of the ternary material.

[0005] In some embodiments, the fluorine-containing material includes at least one of polyvinylidene fluoride, fluorinated acrylate, lithium hexafluorophosphate, lithium tetrafluorophosphate, and lithium difluorophosphate. Thus, the aforementioned fluorine-containing materials can be decomposed and combined to form inorganic fluorides through the mixed roasting treatment, and the inorganic fluorides have high reaction activity.

[0006] In some embodiments, the inorganic base includes at least one of ammonia water and lithium hydroxide. Thus, the aforementioned inorganic base can react with the fluorine-containing material under the mixed roasting treatment, wherein the fluorine-containing material can decompose to generate hydrogen fluoride (HF), and HF can further react with the inorganic base to generate inorganic fluorides.

[0007] In some embodiments, the ternary material mixture includes an inorganic fluoride salt, where the inorganic fluoride salt includes at least one of ammonium fluoride, lithium fluoride, and hydrogen fluoride. Thus, the inorganic fluoride salt obtained through the mixed roasting treatment can be used as a reaction raw material for preparing the doped ternary material in the subsequent process, realizing the utilization of the fluorine-containing material in the waste ternary material.

[0008] In some embodiments, during the mixed roasting treatment, the mass of the inorganic base is m, and m = (m1×w F ) / M F ×M, where m1 is the mass of the waste ternary material, w F is the mass fraction of fluorine element in the waste ternary material, M F is the relative atomic mass of fluorine atoms, and M is the relative molecular weight of the inorganic base. Thus, the inorganic base can be dosed in a controlled manner based on the mass fraction of fluorine element in the waste ternary material or the amount of fluorine element to be doped, which is beneficial to controlling the effect of the subsequent fluorine element-doped modified ternary material.

[0009] In some embodiments, the temperature of the mixed roasting treatment is 300°C - 500°C, and the time of the mixed roasting treatment is 1h - 5h. Thus, the further damage to the structure of the waste ternary material during the recycling process can be reduced, and it is beneficial to the conversion of the fluorine-containing material into the inorganic fluoride salt.

[0010] In some embodiments, the temperature of the oxygen-enriched roasting treatment is 750°C - 950°C, and the time of the oxygen-enriched roasting treatment is 8h - 15h. Thus, under the conditions of the foregoing oxygen-enriched roasting treatment, it is beneficial to the formation of a doped ternary material with relatively uniform doping and a relatively stable material structure, so that the doped ternary material can have better cycle stability and thermal stability.

[0011] In some embodiments, the oxygen flow rate during the oxygen-enriched roasting treatment is 100m 3 / h - 400m 3 / h. Thus, it is beneficial to prepare a doped ternary material with a stable layered structure and a low degree of mixed arrangement, which has high cycle performance.

[0012] In some embodiments, it further includes: before the oxygen-enriched roasting treatment, performing a water washing treatment on the ternary material mixture until the pH value of the ternary material mixture is 9 - 12. Thus, the interfering substances during the oxygen-enriched roasting treatment can be reduced, and the alkalinity of the ternary material mixture can be controlled, which is beneficial to preparing a doped ternary material with controllable doping amount, uniform doping, and a stable structure.

[0013] In some embodiments, it further includes: introducing the tail gas generated by the mixed roasting treatment into the water washing solution of the water washing treatment, and the pH value of the water washing solution is 11-13. Thereby, the utilization rate of fluorine elements in the waste ternary material can be improved.

[0014] In the second aspect of the present application, the present application proposes a doped ternary material, which is prepared by the method proposed by the present application. The doped ternary material satisfies the chemical formula: Li a Ni x Co y M 1-x-y O 2-z F z , where 0.9≤a≤1.2, 1>x>0, 1>y≥0, 0<z≤0.04, and 0<x + y<1, and M includes Mn and / or Al.

[0015] In the doped ternary material proposed by the present application, as a doping element, fluorine elements can effectively inhibit the mixing of lithium and nickel, making the doped ternary material have a relatively stable layered structure. Thereby, the cation arrangement in the layered structure of the doped ternary material is relatively orderly, and the deintercalation and intercalation of lithium ions are relatively easy, which is beneficial to stabilizing the crystal structure of the doped ternary material and making the doped ternary material have high cycle performance.

[0016] In the third aspect of the present application, the present application proposes a lithium-ion battery, and the lithium-ion battery includes the doped ternary material proposed by the present application.

[0017] The lithium-ion battery proposed by the present application includes the doped ternary material proposed by the present application and has a high specific capacity and a relatively stable crystal structure. Thereby, the lithium-ion battery can have a high battery capacity and excellent cycle performance. Detailed implementation manners

[0018] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs; the terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; unless otherwise stated, the numerical values of the various parameters mentioned in the present application can be measured by various common measurement methods in the art (for example, they can be tested according to the methods given in the embodiments of the present application).

[0019] The terms "including" and "having" and any variations thereof in the specification and claims of the present application are open expressions, that is, including the content specified in the present application, but not excluding other aspects.

[0020] In the description of the present application, all the numbers disclosed herein are approximate values, whether or not the words "about" or "approximate" are used. There may be a difference of less than 10% in the value of each number or a reasonable difference considered by those skilled in the art, such as a difference of 1%, 2%, 3%, 4% or 5%.

[0021] The "ranges" disclosed in the present application are defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4 and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4 and 2 - 5. In the present application, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" represents all the real numbers between "0 - 5" that have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0022] If there is no special instruction, all the embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0023] If there is no special instruction, all the technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0024] In the composition of a lithium - ion battery, the positive electrode active material contains a large number of metal elements that are expensive and have relatively limited mineral resources. Especially for ternary materials, the metal elements such as lithium, nickel, cobalt, and manganese contained therein have high recycling value due to factors such as price and smelting difficulty. Moreover, ternary materials have a layered structure and are one of the positive electrode materials for preparing high - energy - density lithium - ion batteries. In the layered structure of ternary materials, cations are prone to cation mixing, which in turn affects their cycle life and thermal stability. By ion - doping modification of ternary materials and introducing cations or anions into the lattice, their cycle performance can be improved.

[0025] Lithium-ion batteries need to stably and continuously operate normally during charging and discharging at a relatively high oxidation potential, so it is required that the relevant materials in lithium-ion batteries have high electrochemical stability. Fluorine-containing materials have the characteristic of high chemical stability. Applying fluorine-containing materials in lithium-ion batteries can improve the cycle stability and safety of lithium-ion batteries, and they have been widely used in the manufacture of lithium-ion batteries. Adding fluorine-containing materials, such as fluorides and fluorine-containing resins, during the preparation of lithium-ion batteries can improve the performance of electrode materials and optimize the performance of electrolytes. Specifically, fluorine-containing resins can be used as binders for electrode materials to effectively fix electrode materials, and fluorides can be used as additives in electrolytes to improve the stability of electrolytes. Therefore, there is usually a certain amount of fluorine-containing materials in the waste positive electrode materials generated by lithium-ion batteries. However, in the related art, when recycling positive electrode materials, it is difficult to separate and process fluorine-containing materials. Fluorine-containing materials are highly corrosive to equipment during the separation and treatment process, and produce toxic and harmful secondary wastes, causing environmental pollution.

[0026] The method for recycling waste ternary positive electrode materials proposed in this application can utilize the fluorine element in the fluorine-containing materials in lithium-ion batteries to prepare doped ternary materials with fluorine element doping during the recycling process of waste ternary positive electrode materials. It not only reuses ternary materials, realizes the sustainable utilization of resources, but also realizes the modification of ternary materials in the same process, improving the material performance of ternary materials.

[0027] In the first aspect of this application, this application proposes a method for recycling waste ternary positive electrode materials, including: performing a mixed roasting treatment on the waste ternary materials and inorganic alkali to obtain a ternary material mixture, wherein the waste ternary materials include fluorine-containing materials; performing an oxygen-enriched roasting treatment on the ternary material mixture to obtain doped ternary materials.

[0028] The binding states of metal ions such as lithium, nickel, and manganese in waste ternary materials change due to the destruction of the crystal structure of the ternary materials. During the disassembly and recycling process of lithium-ion batteries, the electrolyte and binder in the positive electrode sheet of the lithium-ion battery may be mixed into the recycled waste ternary materials. Among them, the fluorine-containing lithium salts commonly used in electrolytes, such as lithium hexafluorophosphate, and fluorine-containing materials such as polyvinylidene fluoride commonly used in binders have special properties and are difficult to remove by treatment methods such as water washing and simple roasting. The method for recycling waste ternary cathode materials proposed in this application performs a controlled roasting treatment on the inorganic base and the waste ternary materials to convert the fluorine-containing materials into inorganic fluorides, obtaining a mixture containing inorganic fluorides and ternary materials. The highly reactive fluoride ions in the inorganic fluorides are doped into the ternary materials during the oxygen-rich roasting treatment, participating in the process of structural remodeling of the ternary materials and optimizing and adjusting the crystal structure of the ternary materials as doping elements. Thus, this method can efficiently recycle waste ternary materials and effectively utilize the fluorine-containing materials in the waste ternary materials as resources. By means of fluorine element doping, doped ternary materials are prepared during the process of crystal structure remodeling of the ternary materials.

[0029] In some embodiments, the fluorine-containing materials include at least one of polyvinylidene fluoride, fluorinated acrylate, lithium hexafluorophosphate, lithium tetrafluorophosphate, and lithium difluorophosphate. The fluorine-containing materials can come from the fluorine-containing lithium salts in the electrolyte and the fluorine-containing binders in the electrode materials. The chemical bonds in the aforementioned fluorine-containing materials can undergo chemical changes during the mixed roasting treatment with the inorganic base, and through the processes of decomposition and combination, inorganic fluorides are generated. Thus, the aforementioned fluorine-containing materials can be decomposed and combined through the mixed roasting treatment to form inorganic fluorides with relatively high reactivity.

[0030] In some embodiments, the waste ternary materials include carbon-containing substances, where the carbon-containing substances include at least one of graphite, conductive carbon black, carbon nanotubes, carbon nanofibers, and amorphous carbon. The fluorine-containing materials containing carbon elements can decompose to produce amorphous carbon during the mixed roasting treatment; during the recycling process of the waste ternary materials, the mixing of the negative electrode active material in the negative electrode sheet can cause the collected waste ternary materials to contain carbon-containing substances. During the oxygen-rich roasting treatment, the carbon-containing substances can undergo an oxidation reaction to produce gaseous carbon-containing oxides, such as CO2, and thus can be separated from the prepared doped ternary materials.

[0031] In some embodiments, the inorganic base includes at least one of ammonia water and lithium hydroxide. Thus, the aforementioned inorganic base can react with the fluorine-containing materials under the mixed roasting treatment, where the fluorine-containing materials can decompose to generate hydrogen fluoride (HF), and HF can further react with the inorganic base to form inorganic fluorides.

[0032] In some embodiments, the inorganic base includes lithium hydroxide. Lithium ions are contained in lithium hydroxide and can react with the acidic fluoride generated during the decomposition of the fluorine-containing material to form lithium fluoride (LiF). During the oxygen-rich roasting treatment, LiF can serve as a lithium supplement agent and a fluorine source, which can not only provide fluoride ions as doping elements but also adjust the lithium content in the prepared doped ternary material. Thus, the inorganic base can increase the lithium content of the waste ternary cathode material obtained by the recycling treatment, which is beneficial to improving the energy density of the prepared doped ternary material.

[0033] In some embodiments, the ternary material mixture includes inorganic fluorides, where the inorganic fluorides include at least one of ammonium fluoride, lithium fluoride, and hydrogen fluoride.

[0034] The fluorine-containing material mixed in the waste ternary material is mixed and roasted with the inorganic base. Due to different fluorine-containing materials, the reaction processes are different. Among lithium salts, for example, lithium hexafluorophosphate can decompose to form inorganic fluoride lithium fluoride. In the positive electrode sheet, the organic fluorine-containing material, such as the binder polyvinylidene fluoride (PVDF), decomposes, its molecular chain breaks, and the generated compounds include carbon substances, benzene fluoride, and HF, where HF can form inorganic fluorides with the inorganic base. Thus, the inorganic fluorides obtained through the mixed roasting treatment can be used as reaction raw materials for the subsequent preparation of doped ternary materials, realizing the utilization of the fluorine-containing material in the waste ternary material.

[0035] In some embodiments, during the mixed roasting treatment, the mass of the inorganic base is m, and m = (m1 × w F ) / M F × M, where m1 is the mass of the waste ternary material, w F is the mass fraction of fluorine element in the waste ternary material, M F is the relative atomic mass of fluorine atoms, and M is the relative molecular weight of the inorganic base.

[0036] The content of the fluorine-containing material mixed in the waste ternary material varies due to factors such as the recycling channel and the recycling source, and the types and fluorine contents of the fluorine-containing materials also vary. The mass fraction w F of the fluorine element in the waste ternary material is measured by the national standard method for fluorine testing (HJ 999-2018) based on the mass of the waste ternary material. Through the aforementioned method of calculating the mass of the inorganic base, the maximum dosage of the inorganic base can be calculated according to the fluorine content in the waste ternary material. Using the inorganic base with the calculated maximum dosage can generate inorganic fluorides during the mixed roasting treatment and reduce side reactions and waste caused by excessive feeding. Thus, the inorganic base can be dosed based on the mass fraction of the fluorine element in the waste ternary material or the amount of fluorine element to be doped, which is beneficial to controlling the effect of the subsequent modification of the ternary material by doping fluorine elements.

[0037] In some embodiments, the mass of the calculated inorganic base is m = r×(m1×w F ) / M F ×M, where 0.5 ≤ r ≤ 1. Thus, the amount of the inorganic base and the amount of the doped fluorine element can be adjusted by the proportional parameter r.

[0038] In some embodiments, the temperature of the mixed roasting treatment is 300°C - 500°C, and the time of the mixed roasting treatment is 1 h - 5 h. Within the foregoing temperature range and time range of the mixed roasting treatment, the fluorine-containing material can undergo a decomposition reaction and react with the inorganic base to form an inorganic fluoride salt. Some of the gases generated by the decomposition of the fluorine-containing material can be fully separated by heat. At the same time, within the foregoing temperature range, the properties and structure of the ternary material are relatively stable, which is conducive to fluorine element doping during the subsequent oxygen-rich roasting treatment. Thus, further damage to the structure of the waste ternary material during the recycling process can be reduced, and the conversion of the fluorine-containing material into an inorganic fluoride salt is facilitated.

[0039] In some embodiments, the temperature of the oxygen-rich roasting treatment is 750°C - 950°C, and the time of the oxygen-rich roasting treatment is 8 h - 15 h. Within the foregoing temperature range of the oxygen-rich roasting treatment, sufficient energy can be provided to enable fluoride ions to enter the lattice structure of the ternary material, break the original bond connection between oxygen atoms and metal ions, and form new chemical bonds between fluoride ions and metal ions. The ionic radius of fluoride ions is smaller, and fluoride ions have a higher electronegativity, which can form more stable connections with metal ions and enhance the binding force of the lattice. Within the foregoing time range of the oxygen-rich roasting treatment, the fluorine element doping is relatively uniform, and the layered structure of the prepared doped ternary material is relatively stable. Thus, under the foregoing conditions of the oxygen-rich roasting treatment, it is conducive to the formation of a doped ternary material with relatively uniform doping and stable material structure by fluorine element doping, so that the doped ternary material can have good cycle stability and thermal stability.

[0040] In some embodiments, the oxygen flow rate of the oxygen-rich roasting treatment is 100 m 3 / h - 400 m 3 / h. Under the foregoing oxygen flow rate conditions of the oxygen-rich roasting, it is conducive to stabilizing the oxidation state in the structure of the ternary material, reducing the formation of Ni 2 +, thereby reducing the degree of cation mixing and facilitating the formation of a low-resistance channel for lithium ion deintercalation in the doped ternary material. Thus, it is conducive to preparing a doped ternary material with a stable layered structure and low mixing degree, which has high cycle performance.

[0041] In some embodiments, it further includes: before performing the oxygen-enriched roasting treatment, performing a water washing treatment on the ternary material mixture until the pH value of the ternary material mixture is 9-12. Through the water washing treatment, soluble salts that may be contained in the ternary material mixture, impurities such as dust attached to the surface, and unreacted inorganic bases are removed from the ternary material mixture. Thereby, interfering substances in the oxygen-enriched roasting treatment process can be reduced, and the alkalinity of the ternary material mixture can be controlled, which is beneficial to preparing a doped ternary material with a controllable doping amount, uniform doping, and a stable structure.

[0042] In some embodiments, it further includes: introducing the tail gas generated by the mixed roasting treatment into the water washing solution of the water washing treatment, and the pH value of the water washing solution is 11-13.

[0043] The fluorine-containing material can decompose to form HF during the mixed roasting process. HF is a gas at room temperature. If the generated HF does not react with the inorganic base during the mixed roasting process, it can be mixed into the tail gas. Introducing the tail gas generated by the mixed roasting treatment into the water washing solution can react with a certain amount of inorganic base added to the water washing solution so that HF reacts with the inorganic base in the liquid phase, thereby preparing a water washing solution containing inorganic fluorinated salts. Using the water washing solution containing inorganic fluorinated salts for the water washing treatment can recycle the inorganic fluorinated salts therein. Thereby, the utilization rate of fluorine elements in the waste ternary material can be improved.

[0044] In the second aspect of the present application, the present application proposes a doped ternary material prepared by the method proposed by the present application. The doped ternary material satisfies the chemical formula: Li a Ni x Co y M 1-x-y O 2-z F z , where 0.9 ≤ a ≤ 1.2, 1 > x > 0, 1 > y ≥ 0, 0 < z ≤ 0.04, and 0 < x + y < 1, and M includes Mn and / or Al.

[0045] In the doped ternary material proposed by the present application, the fluorine element, as a doping element, can effectively inhibit the mixing of lithium and nickel, making the doped ternary material have a relatively stable layered structure. Thereby, the cation arrangement in the layered structure of the doped ternary material is relatively orderly, and the lithium ion deintercalation is relatively easy, which is beneficial to stabilizing the crystal structure of the doped ternary material and making the doped ternary material have high cycle performance.

[0046] In the third aspect of the present application, the present application proposes a lithium ion battery, and the lithium ion battery includes the doped ternary material proposed by the present application.

[0047] The lithium-ion battery proposed in this application includes the doped ternary material proposed in this application, which has a high specific capacity and a relatively stable crystal structure. Therefore, this lithium-ion battery can have a high battery capacity and excellent cycling performance.

[0048] The following uses specific examples to illustrate the solution of this application. It should be noted that the following examples are only used to illustrate this application and should not be regarded as limiting the scope of this application. For technologies or conditions not specified in the examples, they shall be carried out according to the technologies or conditions described in the literature in this field or according to the product instructions. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchases.

[0049] Example 1

[0050] S1: Pass the scrapped ternary cathode powder through a 300-mesh to 400-mesh sieve to obtain the separated waste ternary material, including the ternary material LiNi 0.5 Co 0.2 Mn 0.3 O2, the fluorine-containing material PVDF;

[0051] S2: Take 250 g of the waste ternary material powder in S1 (the mass fraction of fluorine element measured is 1.7%) and 2.68 g of lithium hydroxide for uniform mixing, and then place it in a muffle furnace for mixed roasting treatment. Roast it in an air atmosphere at 480 °C for 5 h to obtain a ternary material mixture;

[0052] S3: According to the required F ion doping amount of 0.15%, take the ternary material mixture prepared in S2 and place it in a 2.5 L container, and wash it with pure aqueous solution until the pH of the slurry is 11, filter, and dry it at 200 °C for 2 h;

[0053] S4: Place the ternary material mixture after the water washing treatment in S3 in a heating furnace for oxygen-enriched roasting treatment. Heat it up to 800 °C at a heating rate of 5 °C / min in an oxygen atmosphere, keep it at a constant temperature for 12 h. Then cool it down to 300 °C at a rate of 5 °C / min, and finally cool it naturally to obtain the doped ternary material, whose chemical formula is LiNi 0.5 Co 0.2 M 0.3 O 1.19 F 0.01 .

[0054] Example 2

[0055] S1: Pass the scrapped ternary cathode powder through a 300-mesh to 400-mesh sieve to obtain the separated waste ternary material, including the ternary material LiNi 0.8 Co 0.15 Mn 0.05 O2, the fluorine-containing material PVDF;

[0056] S2: Take 250 g of the waste ternary material powder (the measured mass fraction of fluorine element is 1.7%) in S1 and 3.2 g of lithium hydroxide, mix them evenly, and then place them in a muffle furnace for mixed roasting treatment. Roast them in an air atmosphere at 480 °C for 5 h to obtain a ternary material mixture;

[0057] S3: According to the required F ion doping amount of 0.5%, take the ternary material mixture prepared in S2 and place it in a 2.5 L container, wash it with pure aqueous solution until the pH of the slurry is 11.5, filter, and dry it at 200 °C for 2 h;

[0058] S4: Place the ternary material mixture after the water washing treatment in S3 in a heating furnace for oxygen-rich roasting treatment. Heat it up to 750 °C at a heating rate of 5 °C / min in an oxygen atmosphere, and keep it at a constant temperature for 12 h. Then cool it down to 300 °C at a rate of 5 °C / min, and finally cool it naturally to obtain the doped ternary material, whose chemical formula is LiNi 0.8 Co 0.15 M 0.05 O 1.175 F 0.025 。

[0059] Example 3

[0060] S1: Pass the scrapped ternary cathode powder through a 300-mesh to 400-mesh sieve to obtain the separated waste ternary material, including the ternary material LiNi 0.8 Co 0.15 Mn 0.05 O2, fluorine-containing material PVDF;

[0061] S2: Take 250 g of the waste ternary material powder (the measured mass fraction of fluorine element is 1.7%) in S1 and 4.3 g of lithium hydroxide, mix them evenly, and then place them in a muffle furnace for mixed roasting treatment. Roast them in an air atmosphere at 480 °C for 5 h to obtain a ternary material mixture;

[0062] S3: According to the required F ion doping amount of 0.8%, take the ternary material mixture prepared in S2 and place it in a 2.5 L container, wash it with pure aqueous solution until the pH of the slurry is 11.5, filter, and dry it at 200 °C for 2 h;

[0063] S4: Place the ternary material mixture after the water washing treatment in S3 in a heating furnace for oxygen-rich roasting treatment. Heat it up to 750 °C at a heating rate of 5 °C / min in an oxygen atmosphere, and keep it at a constant temperature for 12 h. Then cool it down to 300 °C at a rate of 5 °C / min, and finally cool it naturally to obtain the doped ternary material, whose chemical formula is LiNi 0.8 Co 0.15 M 0.05 O 1.16F 0.04 。

[0064] Comparative Example 1

[0065] S1: Pass the scrapped ternary cathode powder through a 300 - 400 mesh sieve to obtain the separated waste ternary material, including the ternary material LiNi 0.8 Co 0.15 Mn 0.05 O2, and the fluorine - containing material PVDF;

[0066] S2: Take 250 g of the waste ternary material powder in S1 (the mass fraction of fluorine element measured is 1.7%) and 0 g of lithium hydroxide for uniform mixing, and then place it in a muffle furnace for mixed roasting treatment. Roast it in an air atmosphere at 480°C for 5 h to obtain a ternary material mixture;

[0067] S3: According to the required F ion doping amount of 0%, take the ternary material mixture prepared in S2 and place it in a 2.5 L container, and wash it with pure aqueous solution until the pH of the slurry is 10.5, then filter and dry it at 200°C for 2 h;

[0068] S4: Place the ternary material mixture after the water washing treatment in S3 in a heating furnace for oxygen - rich roasting treatment. Heat it up to 750°C at a heating rate of 5°C / min in an oxygen atmosphere, keep the temperature constant for 12 h. Then cool it down to 300°C at a rate of 5°C / min, and finally cool it naturally to obtain the doped ternary material, whose chemical formula is LiNi 0.8 Co 0.15 M 0.05 O2F0.

[0069] Testing method:

[0070] 1. F doping amount test: Alkali fusion - fluoride ion selective electrode method

[0071] 2. Qualitative detection of X - ray diffraction (XRD) unit cell parameters

[0072] 3. Cycle retention rate test:

[0073] At room temperature, mix the redoped ternary material: conductive agent (conductive carbon + carbon nanotubes): binder (polyvinylidene fluoride) in a mass ratio of 94:3:3, add an appropriate amount of N - methylpyrrolidone (NMP) and stir until it becomes viscous to obtain the positive electrode slurry. Coat the positive electrode slurry evenly on the aluminum foil, dry it at 120°C, cut it into pieces and assemble it with metallic lithium into a single - cell half - battery. At room temperature, the battery is charged at a 1C rate and discharged at a 1C rate. Stop the test after 100 cycles, and calculate the capacity retention rate after 100 cycles = discharge capacity of the 100th cycle / discharge capacity of the 1st cycle.

[0074] Test results: See Table 1.

[0075] Table 1

[0076]

[0077] As can be seen from Table 1, by the method proposed in this application, the ternary material is recycled and a certain amount of fluorine element doping is achieved, which is beneficial to restricting the cation mixing degree in the ternary material and using the high electronegativity of the fluorine element to limit the crystal structure of the ternary material, which is beneficial to improving the cycle performance of the prepared doped ternary material. Therefore, the doping ratio of the fluorine element in the doped ternary material proposed in this application is appropriate, which is beneficial to giving full play to the role of fluorine element doping in optimizing the stability of the layered structure of the ternary material.

[0078] In this application, the writing order of each step does not mean a strict execution order that constitutes any limitation to the implementation process. The specific execution order of each step should be determined by its function and possible internal logic. If there is no special instruction, all steps of this application can be carried out in sequence or randomly, and preferably in sequence. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out in sequence, or may also include steps (b) and (a) carried out in sequence. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may also include steps (a), (c) and (b), or may also include steps (c), (a) and (b), etc.

[0079] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples, and embodiments with the same constitution and the same effect as the technical idea within the technical solution scope of this application are all included in the technical scope of this application. In addition, within the scope of not departing from the gist of this application, various modifications that can be thought of by those skilled in the art to the embodiments and other ways constructed by combining some constituent elements of the embodiments are also included in the scope of this application.

Claims

1. A method for recycling waste ternary cathode materials, characterized in that, Comprising: Performing a mixed roasting treatment on waste ternary materials and inorganic bases to obtain a ternary material mixture, wherein the waste ternary materials include fluorine-containing materials; Performing an oxygen-enriched roasting treatment on the ternary material mixture to obtain a doped ternary material.

2. The method according to claim 1, wherein The fluorine-containing material includes at least one of polyvinylidene fluoride, fluorinated acrylate, lithium hexafluorophosphate, lithium tetrafluorophosphate, and lithium difluorophosphate.

3. The method according to claim 1, wherein The inorganic base includes at least one of ammonia water and lithium hydroxide.

4. The method according to claim 1, wherein The ternary material mixture includes inorganic fluorinated salts, wherein the inorganic fluorinated salts include at least one of ammonium fluoride, lithium fluoride, and hydrogen fluoride.

5. The method according to any one of claims 1-4, wherein During the mixed roasting treatment, the mass of the inorganic base is m, and m = (m1×w F ) / M F ×M, where m1 is the mass of the waste ternary material, w F is the mass fraction of fluorine element in the waste ternary material, M F is the relative atomic mass of fluorine atom, and M is the relative molecular weight of the inorganic base.

6. The method according to any one of claims 1-4, wherein The temperature of the mixed roasting treatment is 300°C - 500°C, and the time of the mixed roasting treatment is 1h - 5h; and / or, The temperature of the oxygen-enriched roasting treatment is 750°C - 950°C, and the time of the oxygen-enriched roasting treatment is 8h - 15h; and / or, The oxygen flow rate for the oxygen-enriched roasting treatment is 100 m 3 / h - 400 m 3 / h.

7. The method according to claim 1, wherein Comprising: Before performing the oxygen-enriched roasting treatment, performing a water washing treatment on the ternary material mixture until the pH value of the ternary material mixture is 9 - 12.

8. The method according to claim 7, characterized in that, Comprising: Introducing the tail gas generated by the mixed roasting treatment into the water washing solution of the water washing treatment, and the pH value of the water washing solution is 11 - 13.

9. A doped ternary material, characterized in that, Prepared by the method according to any one of claims 1-8, wherein the doped ternary material satisfies the chemical formula: Li a Ni x Co y M 1-x-y O 2-z F z , where 0.9 ≤ a ≤ 1.2, 1 > x > 0, 1 > y ≥ 0, 0 < z ≤ 0.04, and 0 < x + y < 1, and M includes Mn and / or Al.

10. A lithium-ion battery, characterized in that, The lithium-ion battery includes the doped ternary material according to claim 9.

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