Denitration catalyst based on positive electrode material of waste lithium ion battery and preparation method of denitration catalyst

Abstract

The invention relates to the technical field of waste lithium ion battery resource utilization, in particular to a denitration catalyst based on a waste lithium ion battery positive electrode material and a preparation method thereof.The preparation method comprises the steps that a mixed solution of sulfuric acid, organic acid and hydrogen peroxide is added into waste ternary positive electrode material powder, and then the mixture is placed in a microwave reactor to be subjected to microwave treatment; slowly adding a carbonate solution into the filtrate obtained after microwave treatment, violently stirring at the same time, continuously stirring for 1-5 hours after dropwise adding is completed, and sequentially filtering, washing, drying and crushing to obtain recycled powder; uniformly mixing the recycled powder with TiO2, sequentially adding an active component solution, an inorganic binder, an organic binder and glass fibers, and then sequentially performing mixing, extrusion molding, drying and calcining to obtain the denitration catalyst. According to the method, resource utilization of the waste lithium ion battery is achieved, the low-temperature denitration activity of the denitration catalyst is improved, an active temperature window is widened, and the denitration catalyst is endowed with excellent synergistic VOCs removal performance.

Description

Technical Field

[0001] The present invention relates to the technical field of resource utilization of waste lithium - ion batteries, and particularly to a denitration catalyst based on the cathode material of waste lithium - ion batteries and a preparation method thereof. Background Art

[0002] With the transformation of the global energy structure and the enhancement of environmental awareness, lithium - ion batteries, as the core components in the fields of new - energy vehicles and energy storage, have rapidly expanded their application scope and market demand. Lithium - ion batteries have become the leaders in current electrochemical energy - storage technologies due to their high energy density, low self - discharge rate, long cycle life, and relatively safe and stable operating characteristics.

[0003] However, with the large - scale use of lithium - ion batteries, the problem of treating waste lithium - ion batteries has become increasingly prominent, posing an environmental challenge that urgently needs to be solved. Waste lithium - ion batteries contain a large amount of transition metal elements such as nickel, cobalt, and manganese. These elements not only have significant economic value but also pose a potential threat to the environment. Therefore, effectively recovering the useful elements in waste lithium - ion batteries not only helps to reduce environmental pollution but also enables the recycling of resources, which has important economic and environmental significance.

[0004] On the other hand, nitrogen oxides, as one of the main pollutants in the atmosphere, pose a serious threat to human health and the ecological environment. To effectively reduce nitrogen oxide emissions, selective catalytic reduction technology (SCR) has been widely used, and denitration catalysts are the core components of this technology. Traditional denitration catalysts mainly consist of vanadium - molybdenum (tungsten) - titanium as the main components, which convert nitrogen oxides into harmless nitrogen and water through catalytic action. In recent years, in order to improve the low - temperature activity, sulfur - resistance performance, and co - removal ability of the catalyst, researchers have begun to try adding transition metal elements to the catalyst in order to obtain more excellent catalytic performance.

[0005] Although significant progress has been made in the research and application of denitration catalysts, the research on preparing denitration catalysts using waste lithium - ion battery materials is still relatively scarce. In the prior art, for example, the invention patent CN202211611914.2 discloses a method for preparing a denitration catalyst using waste lithium - battery materials. This method attempts to prepare a denitration catalyst using the positive and negative electrode materials of waste lithium - batteries and modifies it through steps such as adding acids and ammonium salts. However, this method has problems such as poor leaching effect, and the related performance and co - removal ability of the prepared catalyst are not strong, which limits its promotion and effectiveness in practical applications.

[0006] Therefore, in view of the urgent need for recycling waste lithium-ion batteries and the importance of improving the performance of denitration catalysts, developing a new method that can efficiently utilize the ternary cathode materials of waste lithium-ion batteries to prepare high-performance denitration catalysts has become a key technical problem that urgently needs to be solved in this field. This not only helps to realize the resource utilization of waste lithium-ion batteries but also promotes the further development of denitration catalyst technology, contributing to environmental protection and sustainable development.

[0007] In view of this, the present invention is specifically proposed. Summary of the Invention

[0008] The purpose of the present invention is to provide a denitration catalyst based on the cathode material of waste lithium-ion batteries and a preparation method thereof. This method not only realizes the resource utilization of waste lithium-ion batteries but also improves the low-temperature denitration activity of the denitration catalyst, broadens the active temperature window, and endows the denitration catalyst with excellent performance in synergistic removal of VOCs by optimizing the preparation process and composition of the catalyst.

[0009] In the first aspect, the present invention provides a preparation method of a denitration catalyst based on the cathode material of waste lithium-ion batteries, including the following steps:

[0010] S1. Add a mixed solution of sulfuric acid, organic acid, and hydrogen peroxide to the waste ternary cathode material powder, and then place it in a microwave reactor for microwave treatment;

[0011] S2. Slowly add a carbonate solution to the filtrate obtained after microwave treatment while stirring vigorously. After the addition is completed, continue to stir for 1 - 5 h, and then successively filter, wash, dry, and pulverize to obtain a recovered powder;

[0012] S3. Mix the recovered powder uniformly with TiO2, and then successively add an active component solution, an inorganic binder, an organic binder, and glass fiber, and then successively mix, extrude into shape, dry, and calcine to obtain a denitration catalyst.

[0013] In the preparation method of the present invention, first, add a mixed solution of sulfuric acid, organic acid, and hydrogen peroxide to the waste ternary cathode material powder and assist with microwave extraction to fully dissolve and leach out Ni, Co, Mn / Al metal ions in the waste lithium-ion battery; then, add carbonate to the filtrate obtained after microwave treatment, and the dissolved metal ions can be precipitated as carbonate. As a precipitate that is easy to filter and wash, the carbonate can be converted into the required catalyst components in subsequent steps; finally, mix the recovered carbonate powder with TiO2, and then add an active component solution, an inorganic binder, an organic binder, and glass fiber. Through steps such as mixing, extrusion into shape, drying, and calcining, the mixture can be converted into a denitration catalyst with a specific shape and structure.

[0014] Therefore, by recycling the ternary cathode material in waste lithium-ion batteries, the present invention realizes the reuse of resources, reduces the dependence on new resources, and lowers the waste treatment cost. Meanwhile, by optimizing the preparation process and composition of the catalyst, the low-temperature denitrification activity of the denitrification catalyst is improved, the active temperature window is broadened, and the denitrification catalyst is endowed with excellent performance for synergistic VOCs removal.

[0015] Preferably, in step S1, the waste ternary cathode material includes any one of NCM and NCA. Among them, NCM includes 111 series, 622 series, 811 series, 523 series, 613 series, and NCA is 80155 series.

[0016] In the present invention, the waste ternary cathode material powder can be prepared by discharging, disassembling, pulverizing, and flotation separation of waste lithium-ion batteries. The following is a specific description of the above steps:

[0017] 1. Discharge

[0018] Immerse the waste lithium-ion battery in an appropriate solution (such as sodium chloride solution) to ensure that the battery is completely discharged.

[0019] 2. Disassembly

[0020] Disassemble the discharged waste lithium-ion battery in a glove box or other dust-free and electrostatic-free environment to separate the components such as the positive electrode, negative electrode, and electrolyte of the battery. Careful operation is required during the disassembly process to avoid damaging the internal structure of the battery, especially the positive and negative electrode materials.

[0021] 3. Pulverization

[0022] Use a knife crusher or other appropriate pulverizing equipment to pulverize the disassembled battery positive electrode material (which may contain impurities such as current collectors and binders) into smaller particles or flake materials to increase the surface area of the material and facilitate separation and recovery in subsequent steps.

[0023] 4. Flotation separation

[0024] Perform flotation separation on the pulverized positive electrode material powder to effectively separate the positive and negative electrode active materials from impurities (such as graphite and conductive agents). Through flotation separation, a relatively pure ternary cathode material powder can be obtained.

[0025] Preferably, in step S1, the solid-liquid ratio of the waste ternary cathode material powder to the mixed solution of sulfuric acid, organic acid, and hydrogen peroxide is 1:(10 - 20), where the concentration of sulfuric acid is 1 - 5 mol / L, the concentration of organic acid is 0.5 - 2 mol / L, and the concentration of hydrogen peroxide is 1 - 10 wt%.

[0026] Preferably, the organic acid includes any one or more of sulfamic acid, oxalic acid, ethanedioic acid and formic acid.

[0027] In the present invention, the above-mentioned organic acid is selected to act synergistically with sulfuric acid and hydrogen peroxide. First, it can enhance the solubility of metal ions such as Ni, Co, Mn / Al in the waste ternary cathode material powder and accelerate the reaction rate between metal ions and the solvent, making them more easily leached out during the microwave treatment process, laying a foundation for the recovery and utilization of metal ions in subsequent steps. Second, when a carbonate solution is added to the filtrate obtained after microwave treatment, the presence of the organic acid can affect the morphology and particle size distribution of the precipitate, making it easier to filter and wash. And some organic acids (such as oxalic acid) have the ability to form complexes with metal ions, which can stabilize the metal ions in the solution, preventing them from aggregating or precipitating unevenly during the precipitation process, and is beneficial to improving the purity and uniformity of the recovered powder. Finally, the addition of the organic acid can also affect the composition and structure of the catalyst, thereby improving its catalytic activity. For example, ethanedioic acid can promote the formation of metal-organic framework materials (MOFs), providing more active sites for the catalyst. Sulfamic acid can endow the denitration catalyst with the performance of synergistically removing volatile organic compounds (VOCs), further broadening the application range of the catalyst.

[0028] Preferably, in step S1, during the microwave treatment, the temperature is controlled at 70 - 90 °C and the time is 5 - 20 min.

[0029] Preferably, in step S2, in the carbonate solution, the molar amount of CO3 2- is 2.05 - 2.2 times the molar amount of metal elements in the ternary cathode material, where the carbonate includes any one of Na2CO3 and K2CO3.

[0030] Preferably, in step S3, the active component solution is any one of ammonium metavanadate solution, cerium nitrate solution and cerium acetate solution. Among them, the dosage of the active component solution is preferably such that the mass fraction of the active component oxide in the denitration catalyst is 1 wt% - 5 wt%, and the mass fractions of the oxides of Ni, Co and Mn elements are all 0.5 wt% - 5 wt%;

[0031] The inorganic binder is any one of attapulgite, montmorillonite, sepiolite and wollastonite, and the addition amount of the inorganic binder is 1% - 5% of the mass of the mixture of the recovered powder and TiO2;

[0032] The organic binder is any one of polyvinyl alcohol, polyethylene glycol and paraffin, and the addition amount of the organic binder is 1%-3% of the mass of the mixture of the recycled powder and TiO2.

[0033] The addition amount of the glass fiber is 0.5%-2% of the mass of the mixture of the recycled powder and TiO2;

[0034] Preferably in this technical solution, during the mixing, the time is controlled to be 2-4 h to mix the recycled powder, TiO2, the active component solution, the inorganic binder, the organic binder and the glass fiber to form a paste;

[0035] During the calcination, the temperature is controlled to be 450-600 °C and the time is 2-4 h.

[0036] In the second aspect, the present invention also discloses a denitration catalyst prepared by the above preparation method. In this denitration catalyst, the mass fraction of the active component oxide is 1 wt%-5 wt%, wherein the mass fractions of the oxides of the three elements Ni, Co and Mn are all 0.5 wt%-5 wt%.

[0037] The preparation method of the denitration catalyst based on the waste lithium-ion battery cathode material of the present invention has at least the following beneficial effects:

[0038] 1. In the preparation method of the present invention, first, a mixed solution of sulfuric acid, organic acid and hydrogen peroxide is added to the waste ternary cathode material powder, and microwave extraction is used to fully dissolve and extract the Ni, Co, Mn / Al metal ions in the waste lithium-ion battery; then, carbonate is added to the filtrate obtained after microwave treatment, and the dissolved metal ions can be precipitated as carbonate. As a precipitate that is easy to filter and wash, it can be converted into the required catalyst components in the subsequent steps; finally, the recovered carbonate powder is mixed with TiO2, and then the active component solution, the inorganic binder, the organic binder and the glass fiber are added. Through steps such as mixing, extrusion molding, drying and calcination, the mixture can be converted into a denitration catalyst with a specific shape and structure. The present invention realizes the recycling of resources by recycling the ternary cathode material in the waste lithium-ion battery, reduces the dependence on new resources, and reduces the waste treatment cost. At the same time, by optimizing the preparation process and composition of the catalyst, the low-temperature denitration activity of the denitration catalyst is improved, the active temperature window is broadened, and the denitration catalyst is given excellent performance in synergistic removal of VOCs;

[0039] 2. The present invention uses a mixed acid solution of "inorganic acid + organic acid + hydrogen peroxide" and microwave-assisted treatment, which significantly improves the leaching efficiency of metal ions and shortens the treatment time. Among them, sulfuric acid, as an inorganic acid, can effectively dissolve metal oxides; hydrogen peroxide, as an oxidant, can oxidize metal ions and promote their dissolution; organic acids can further enhance the leaching effect, especially for those metal ions that are difficult to dissolve. Microwave can penetrate the solution, generate heat, cause intermolecular collisions and vibrations, thereby accelerating chemical reactions and improving leaching efficiency;

[0040] 3. By optimizing the composition and structure of the catalyst, the present invention makes full use of the catalytic performance of elements such as Ni, Co, Mn / Al, etc., and improves the denitration activity. Among them, Ni and Co can enhance the surface acidity of the catalyst and adjust the reducibility of the active components; Mn provides additional low-temperature denitration active centers for the catalyst. Therefore, the presence of Mn not only improves the denitration activity at low temperatures, but also broadens the active temperature window of the catalyst, enabling it to maintain high efficiency within a wider temperature range; elements such as Ni, Co, and Mn can also provide catalytic oxidation active centers for VOCs (volatile organic compounds), making the catalyst show better performance when treating multiple pollutants, and further enhancing its industrial applicability. Detailed implementation manners

[0041] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations for the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0042] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary implementation manners according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0043] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0044] Example 1

[0045] This example is based on a preparation method of a denitration catalyst for the positive electrode material of waste lithium-ion batteries, and includes the following steps:

[0046] S1. Take used lithium-ion batteries, and through discharging, disassembling, pulverizing, and flotation separation, obtain used ternary cathode material powder. Add a mixed solution of sulfuric acid, organic acid, and hydrogen peroxide to the used ternary cathode material powder according to a solid-liquid ratio of 1:15, then transfer the mixed solution to a microwave reactor and perform microwave treatment at 80 °C for 10 min. Among them, the concentration of sulfuric acid is 3 mol / L, the concentration of organic acid is 1 mol / L, and the concentration of hydrogen peroxide is 5 wt%.

[0047] S2. Slowly add Na2CO3 solution to the filtrate obtained after microwave treatment while vigorously stirring. After the dropping is completed, continue stirring for 3 h, and then successively filter, wash, dry, and pulverize to obtain the recovered powder. Among them, the molar amount of CO3 2- is 2.1 times the molar amount of metal elements in the ternary cathode material.

[0048] S3. Mix the recovered powder and TiO2 evenly, place them in a mixing tank, successively add the active component solution, inorganic binder, organic binder, and glass fiber. After mixing for 2 - 4 h, form a paste. After extrusion molding, dry it, and then calcine it at 500 °C for 3 h to prepare the denitration catalyst.

[0049] Example 2

[0050] The preparation method of the denitration catalyst based on the used lithium-ion battery cathode material in this example includes the following steps:

[0051] S1. Take used lithium-ion batteries, and through discharging, disassembling, pulverizing, and flotation separation, obtain used ternary cathode material powder. Add a mixed solution of sulfuric acid, organic acid, and hydrogen peroxide to the used ternary cathode material powder according to a solid-liquid ratio of 1:10, then transfer the mixed solution to a microwave reactor and perform microwave treatment at 70 °C for 20 min. Among them, the concentration of sulfuric acid is 1 mol / L, the concentration of organic acid is 2 mol / L, and the concentration of hydrogen peroxide is 5 wt%.

[0052] S2. Slowly add Na2CO3 solution to the filtrate obtained after microwave treatment while vigorously stirring. After the dropping is completed, continue stirring for 1 h, and then successively filter, wash, dry, and pulverize to obtain the recovered powder. Among them, the molar amount of CO3 2- is 2.2 times the molar amount of metal elements in the ternary cathode material.

[0053] S3. Mix the recovered powder and TiO2 evenly, place them in a mixing tank, successively add the active component solution, inorganic binder, organic binder, and glass fiber. After mixing for 2 - 4 h, form a paste. After extrusion molding, dry it, and then calcine it at 450 °C for 4 h to prepare the denitration catalyst.

[0054] Example 3

[0055] The preparation method of the denitration catalyst based on the waste lithium-ion battery cathode material in this embodiment includes the following steps:

[0056] S1. Take the waste lithium-ion battery, and obtain the waste ternary cathode material powder through discharging, disassembling, pulverizing, and flotation separation. Add a mixed solution of sulfuric acid, organic acid, and hydrogen peroxide to the waste ternary cathode material powder according to a solid-liquid ratio of 1:20, and then transfer the mixed solution to a microwave reactor for microwave treatment at 90°C for 5 minutes. Among them, the concentration of sulfuric acid is 5 mol / L, the concentration of organic acid is 0.5 mol / L, and the concentration of hydrogen peroxide is 5 wt%.

[0057] S2. Slowly add the Na2CO3 solution to the filtrate obtained after microwave treatment while stirring vigorously. After the dropping is completed, continue stirring for 5 hours, and then successively filter, wash, dry, and pulverize to obtain the recovered powder. Among them, the molar amount of CO3 2- is 2.05 times the molar amount of metal elements in the ternary cathode material.

[0058] S3. Mix the recovered powder and TiO2 evenly, place them in a mixing cylinder, and successively add the active component solution, inorganic binder, organic binder, and glass fiber. After mixing for 2 - 4 hours, form a paste. After extrusion molding, dry it, and then calcine it at 550°C for 2 hours to prepare the denitration catalyst.

[0059] Example 4

[0060] The preparation method of the denitration catalyst based on the waste lithium-ion battery cathode material in this embodiment includes the following steps:

[0061] S1. Take the waste lithium-ion battery, and obtain the waste ternary cathode material powder through discharging, disassembling, pulverizing, and flotation separation. Add a mixed solution of sulfuric acid, organic acid, and hydrogen peroxide to the waste ternary cathode material powder according to a solid-liquid ratio of 1:15, and then transfer the mixed solution to a microwave reactor for microwave treatment at 80°C for 20 minutes. Among them, the concentration of sulfuric acid is 4 mol / L, the concentration of organic acid is 1 mol / L, and the concentration of hydrogen peroxide is 8 wt%.

[0062] S2. Slowly add the Na2CO3 solution to the filtrate obtained after microwave treatment while stirring vigorously. After the dropping is completed, continue stirring for 4 hours, and then successively filter, wash, dry, and pulverize to obtain the recovered powder. Among them, the molar amount of CO3 2- is 2.15 times the molar amount of metal elements in the ternary cathode material.

[0063] S3. Mix the recycled powder and TiO2 evenly, place them in a mixing tank, and successively add the active component solution, inorganic binder, organic binder, and glass fiber. After mixing for 2 - 4 h, a paste is formed. After extrusion molding, it is dried and then calcined at 600 °C for 3 h to obtain the denitration catalyst.

[0064] Control Example 1

[0065] Conventional denitration catalyst: Place TiO2 in a mixing tank, and successively add the active component (1 wt% - 3 wt% V2O5) and the promoter solution, inorganic binder, organic binder, and glass fiber. After mixing for 2 - 4 h, a paste is formed. After extrusion molding, it is dried and then calcined at 500 °C for 2 h to obtain the denitration catalyst.

[0066] Control Example 2

[0067] This control example is basically the same as Example 1, except that: hydrogen peroxide is not added to the mixed acid solution.

[0068] Control Example 3

[0069] This control example is basically the same as Example 1, except that: the organic acid in the mixed acid solution is replaced with hydrochloric acid.

[0070] Control Example 4

[0071] This control example is basically the same as Example 1, except that: the microwave treatment is replaced with high - speed shear stirring, where the conditions of high - speed shear stirring are: the temperature during stirring is 60 °C, the stirring speed is 18000 rpm, and the stirring time is 10 min.

[0072] Test Example 1

[0073] The present invention tested the denitration performance of the denitration catalysts prepared in the above - mentioned examples and control examples.

[0074] The test conditions are as follows: the test temperature is 380 °C, the NH3 concentration is 500 ppm, NH3 / NO = 1, the SO2 concentration is 300 ppm, the H2O concentration is 8%, and GHSV = 120000 h -1 .

[0075] The denitration efficiencies of different denitration catalysts are shown in Table 1.

[0076] Table 1 Denitration Efficiencies of Different Denitration Catalysts

[0077] Sample Denitration efficiency (%) Example 1 95.9 Example 2 94.7 Example 3 96.5 Example 4 95.4 Control Example 1 90.2 Control Example 2 85.1 Control Example 3 84.6 Control Example 4 81.5

[0078] Test Example 2

[0079] To study the activity of the denitration catalysts prepared in the above examples and comparative examples, the denitration efficiency test was carried out on them at a flue gas temperature of 200 - 450 °C, and the test results are shown in Table 2.

[0080] The test conditions are as follows:

[0081] The test temperature is 200 - 450 °C, the volume concentration of NH3 is 500 ppm, NH3 / NO = 1, the volume concentration of SO2 is 300 ppm, the volume concentration of H2O is 8%, and GHSV = 120000 h -1 .

[0082] Table 2 Denitration efficiency of different catalysts

[0083]

[0084]

[0085] Test Example 3

[0086] To study the catalytic oxidation effect of the denitration catalysts prepared in the above examples and comparative examples on VOCs (volatile organic compounds), toluene was used as the characteristic molecule of VOCs for the de-VOCs test, and the test results are shown in Table 3.

[0087] The test conditions are as follows:

[0088] The test temperature is 200 - 450 °C, the volume concentration of NH3 is 500 ppm, NH3 / NO = 1, the volume concentration of SO2 is 300 ppm, the volume concentration of H2O is 8%, the volume concentration of toluene is 80 ppm, and GHSV = 120000 h -1 .

[0089] Table 3 Toluene removal efficiency of different denitration catalysts

[0090]

[0091]

[0092] As can be seen from Tables 1 - 3, the denitration catalyst prepared based on the waste lithium-ion battery cathode material in the present invention not only improves the low-temperature denitration activity of the denitration catalyst, broadens its active temperature window, but also endows the denitration catalyst with excellent synergistic de-VOCs performance.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a denitration catalyst based on waste lithium-ion battery cathode materials, characterized in that, It includes the following steps: S1. Add a mixed solution of sulfuric acid, organic acid and hydrogen peroxide to the waste ternary cathode material powder, and then place it in a microwave reactor for microwave treatment; S2. Slowly add a carbonate solution to the filtrate obtained after microwave treatment while stirring vigorously. After the dropping is completed, continue to stir for 1 - 5 h, and then successively filter, wash, dry and pulverize to obtain a recovered powder; S3. Mix the recovered powder evenly with TiO2, and successively add an active component solution, an inorganic binder, an organic binder and glass fiber, and then successively mix, extrude into shape, dry and calcine to obtain a denitration catalyst.

2. The preparation method according to claim 1, wherein In step S1, the waste ternary cathode material includes any one of NCM and NCA.

3. The preparation method according to claim 1, wherein, In step S1, the solid-liquid ratio of the waste ternary cathode material powder to the mixed solution of sulfuric acid, organic acid and hydrogen peroxide is 1:(10 - 20), wherein the concentration of sulfuric acid is 1 - 5 mol / L, the concentration of organic acid is 0.5 - 2 mol / L, and the concentration of hydrogen peroxide is 1 - 10 wt%.

4. The preparation method according to claim 1, characterized in that, The organic acid includes any one or more of sulfamic acid, oxalic acid, ethanedioic acid and formic acid.

5. The preparation method according to claim 1, characterized in that, In step S1, during the microwave treatment, control the temperature at 70 - 90 °C and the time at 5 - 20 min.

6. The preparation method according to claim 1, wherein, In step S2, in the carbonate solution, the molar amount of CO3 2- is 2.05 - 2.2 times the molar amount of the metal element in the ternary cathode material; Preferably, the carbonate includes any one of Na2CO3 and K2CO3.

7. The preparation method according to claim 1, wherein In step S3, the active component solution is any one of ammonium metavanadate solution, cerium nitrate solution and cerium acetate solution; The inorganic binder is any one of attapulgite, montmorillonite, sepiolite and wollastonite; The organic binder is any one of polyvinyl alcohol, polyethylene glycol and paraffin.

8. The preparation method according to claim 1, wherein The addition amount of the inorganic binder is 1% - 5% of the mass of the mixture of the recovered powder and TiO2; The addition amount of the glass fiber is 0.5% - 2% of the mass of the mixture of the recovered powder and TiO2; The addition amount of the organic binder is 1% - 3% of the mass of the mixture of the recovered powder and TiO2.

9. The preparation method according to claim 1, characterized in that, During the mixing, control the time at 2 - 4 h; During the calcination, control the temperature at 450 - 600 °C and the time at 2 - 4 h.

10. A denitration catalyst based on the cathode material of waste lithium-ion batteries, characterized in that, Prepared by the preparation method according to any one of claims 1 - 9, in the denitration catalyst, the mass fraction of the active component oxide is 1 wt% - 5 wt%, wherein the mass fraction of the oxides of Ni, Co and Mn three elements is 0.5 wt% - 5 wt%.

Images