Method for removing PVDF from waste lithium batteries used in the entire lithium battery industry chain

Abstract

The present disclosure belongs to the field of lithium battery technology, and specifically relates to a method for removing PVDF from waste lithium batteries used in the entire lithium battery industry chain. By mixing lithium battery waste with a silicic acid solution, and then conducting low-temperature pyrolysis in an oxidizing atmosphere, the silicic acid can decompose in situ in the lithium battery waste during the reaction to produce a large amount of silicon dioxide and water. The surface of the silicon dioxide is rich in silanol groups, which can catalyze the pyrolysis of PVDF at a relatively low temperature. The pyrolysis of PVDF produces HF and a carbon-carbon double-chain polymer. The carbon-carbon double-chain polymer is easily oxidized and broken in an oxidizing atmosphere, thereby further promoting the pyrolysis of PVDF and rendering the bonding effect of PVDF ineffective. The method provided by the present disclosure can achieve the pyrolysis of PVDF at 350°C or even below 350°C, avoiding the problems of temperature runaway and thermite reaction in high-temperature pyrolysis.

Description

Technical Field

[0001] The present disclosure belongs to the field of lithium battery technology, and specifically relates to a method for removing PVDF from waste lithium batteries applied in the entire lithium battery industry chain. Background Art

[0002] The structure of a lithium-ion battery is roughly divided into five parts: the positive electrode, negative electrode, separator, electrolyte, and outer casing. The positive electrode material accounts for the largest proportion of the overall lithium-ion battery's components, with a mass ratio of 3:1 to 4:1. Both positive and negative electrode materials contain active materials, conductive agents, solvents, binders, and matrices. Binders are one of the most important components of lithium-ion battery poles. They are polymer compounds that adhere the active materials and conductive agents in the pole to the electrode current collector. They enhance the contact between the active materials, conductive agents, and current collector, and stabilize the pole structure. They are a high-tech additional material in lithium-ion batteries.

[0003] Polyvinylidene fluoride, abbreviated as PVDF, is a highly non-reactive thermoplastic fluoropolymer, mainly used as a positive electrode binder and diaphragm coating material for lithium batteries, and can be infiltrated by organic electrolytes. Due to its excellent chemical stability and corrosion resistance, PVDF can effectively resist the erosion of polar organic solvent electrolytes and has good bonding properties. Therefore, it is widely used in lithium battery positive electrode binders.

[0004] However, in the process of recycling valuable metals from lithium-ion batteries, how to effectively remove PVDF from the electrodes has become a major challenge. Currently, the most widely used process in industrial production is the high-temperature pyrolysis pretreatment process. Although it can effectively remove PVDF, it also has some major problems: (1) The high-temperature pyrolysis temperature is above 500°C. Due to the complex material types, it is very easy to cause local reactions in the pyrolysis furnace, resulting in temperature runaway; (2) Too high a temperature can easily cause thermite reaction, resulting in a sharp increase in temperature, which brings great safety risks.

[0005] Therefore, seeking a low-temperature pyrolysis method to replace high-temperature pyrolysis is a technical problem that needs to be solved urgently.

[0006] In view of this, the present disclosure is proposed. Summary of the Invention

[0007] The purpose of the present disclosure includes providing a method for removing PVDF from waste lithium batteries applied in the entire lithium battery industry chain, which can achieve pyrolysis of PVDF under low temperature conditions.

[0008] In order to achieve the above-mentioned purpose of the present disclosure, the following technical solutions can be adopted:

[0009] The solution provided by the present disclosure includes providing a method for removing PVDF from waste lithium batteries applied to the entire lithium battery industry chain, comprising: subjecting a mixture of lithium battery waste and silicic acid to low-temperature pyrolysis at 320°C-350°C, and the low-temperature pyrolysis process is carried out in an oxidizing atmosphere.

[0010] In some embodiments of the present disclosure, the temperature of the low-temperature pyrolysis is 330°C-340°C.

[0011] In some embodiments of the present disclosure, the low-temperature pyrolysis time is 5 h to 10 h.

[0012] In some embodiments of the present disclosure, the low-temperature pyrolysis time is 6 h to 8 h.

[0013] In some embodiments of the present disclosure, the low-temperature pyrolysis process is carried out in a pyrolysis furnace, and the temperature is raised to the pyrolysis temperature at a heating rate of 5° C. / min-10° C. / min.

[0014] In some embodiments of the present disclosure, the preparation process of the mixture includes: mixing lithium battery waste and a silicic acid solution.

[0015] In some embodiments of the present disclosure, the mass fraction of the silicic acid solution is 30%-40%.

[0016] In some embodiments of the present disclosure, the mass ratio of lithium battery waste to silicic acid solution is 1:1-1.2.

[0017] In some embodiments of the present disclosure, the mass ratio of lithium battery waste to silicic acid solution is 1:1.05-1.15.

[0018] In some embodiments of the present disclosure, the gas used to form the oxidizing atmosphere is selected from at least one of oxygen and ozone.

[0019] In some embodiments of the present disclosure, the gas used to form the oxidizing atmosphere is ozone.

[0020] In some embodiments of the present disclosure, the introduction rate of the gas used to form the oxidizing atmosphere is 1 mL / min-3 mL / min.

[0021] In some embodiments of the present disclosure, the preparation process of lithium battery waste includes: pre-treating the waste lithium batteries to obtain crushed materials with a particle size that meets the requirements.

[0022] In some embodiments of the present disclosure, pretreatment includes sequentially performing discharging, disassembling, and crushing.

[0023] In some embodiments of the present disclosure, the particle size of the lithium battery waste is less than 5 cm.

[0024] In some embodiments of the present disclosure, the particle size of the lithium battery waste is 1 cm-3 cm.

[0025] In some embodiments of the present disclosure, the waste lithium battery is selected from at least one of a nickel-cobalt-manganese ternary lithium-ion battery, a lithium iron phosphate battery, a lithium cobalt oxide battery, and a lithium iron manganese phosphate battery.

[0026] In some embodiments of the present disclosure, the method further includes treating the HF waste gas generated by the reaction.

[0027] In some embodiments of the present disclosure, HF waste gas is passed into lime water for treatment.

[0028] In some embodiments of the present disclosure, the method further includes: sorting the pyrolyzed scraps to obtain copper and aluminum foils and battery powder.

[0029] In some embodiments of the present disclosure, a double-layer screen is used to screen the pyrolyzed scraps.

[0030] By mixing lithium battery waste with a silicic acid solution and then performing low-temperature pyrolysis in an oxidizing atmosphere, the silicic acid can decompose in situ in the lithium battery waste during the reaction to produce a large amount of silicon dioxide and water. The surface of the silicon dioxide is rich in silanol groups, which can catalyze the pyrolysis of PVDF at a relatively low temperature. The pyrolysis of PVDF produces HF and a carbon-carbon double-chain polymer. The carbon-carbon double-chain polymer is easily oxidized and broken in an oxidizing atmosphere, thereby further promoting the pyrolysis of PVDF and rendering the PVDF adhesive ineffective. The method provided by the present disclosure can achieve the pyrolysis of PVDF at 350°C or even below 350°C, avoiding the problems of temperature runaway and thermite reaction that exist in high-temperature pyrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 Process flow chart for removing PVDF from waste lithium batteries. DETAILED DESCRIPTION

[0033] The embodiments of the present disclosure will be described in detail below with reference to the examples. However, those skilled in the art will appreciate that the following examples are intended only to illustrate the present disclosure and should not be construed as limiting the scope of the present disclosure. Where specific conditions are not specified in the examples, the experiments were performed under conventional conditions or the conditions recommended by the manufacturer. Where the manufacturer of the reagents or instruments is not specified, all are commercially available conventional products.

[0034] The endpoints of the ranges and any values ​​disclosed in this disclosure 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 endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0035] The present disclosure provides a method for removing PVDF from waste lithium batteries in the entire lithium battery industry chain. Figure 1 , including the following steps:

[0036] S1. Preprocessing

[0037] By pre-processing waste lithium-ion batteries, crushed materials with particle size meeting the requirements are obtained, namely lithium battery waste.

[0038] In some embodiments, pretreatment includes sequentially discharging, disassembling, and crushing. Discharging and disassembling are conventional processing steps, and the specific processes are not described in detail. The crushing method is not limited and can be performed using a conventional crusher to reduce the particle size of the lithium battery waste to less than 5 cm, such as 0.1 cm, 1.0 cm, 2.0 cm, 3.0 cm, 4.0 cm, 5.0 cm, etc.

[0039] In some embodiments, the particle size of the lithium battery waste is 1 cm-3 cm, and raw materials with smaller particle sizes are more conducive to promoting the full progress of the reaction.

[0040] In some embodiments, the waste lithium battery is selected from at least one of nickel-cobalt-manganese ternary lithium-ion batteries, lithium iron phosphate batteries, lithium cobalt oxide batteries and lithium manganese iron phosphate batteries. It can be a type of the above common lithium-ion batteries, and the doping elements are not limited. Conventional doping elements are all within the scope of protection of the present disclosure.

[0041] S2. Mixing

[0042] The lithium battery waste is mixed with the silicic acid solution, and the lithium battery waste is evenly dispersed in the solution by stirring. The lithium battery waste can effectively contact with the silicic acid and penetrate into it to obtain a mixture of the lithium battery waste and the silicic acid solution.

[0043] In some embodiments, the mass fraction of the silicic acid solution is 30%-40% (eg, 30%, 35%, 40%, etc.), and the silicic acid solution is a commercially available raw material.

[0044] Furthermore, the mass ratio of lithium battery waste to silicic acid solution is 1:1-1.2, preferably 1:1.05-1.15. The amount of silicic acid used is further controlled to ensure sufficient reaction and removal of PVDF. Specifically, the mass ratio of lithium battery waste to silicic acid solution can be 1:1.00, 1:1.05, 1:1.10, 1:1.15, 1:1.20, etc.

[0045] S3, low temperature pyrolysis

[0046] The mixture obtained in S2 is subjected to low-temperature pyrolysis at 320°C-350°C in an oxidizing atmosphere. Catalytic pyrolysis is performed in a silicic acid solution, with the temperature throughout the process controlled below 400°C, to achieve polymer chain scission and render the PVDF bonding effect ineffective.

[0047] It should be noted that when silicic acid is heated above 150°C, it decomposes in situ within the battery scrap to produce large amounts of silica and water. The silica surface is rich in silanol groups, which can catalyze the thermal decomposition of PVDF at temperatures between 320°C and 350°C. PVDF thermal decomposition produces HF and carbon-carbon double-chain polymers. These double-chain polymers are susceptible to oxidation and chain scission in oxidizing atmospheres such as ozone, further accelerating the thermal decomposition of PVDF. The decomposition reaction equation for silicic acid above 150°C is: H2SiO3 = SiO2 + H2O.

[0048] Specifically, the temperature of low-temperature pyrolysis can be 320°C, 325°C, 330°C, 335°C, 340°C, 345°C, 350°C, etc., preferably 330°C-340°C.

[0049] In some embodiments, the low-temperature pyrolysis time is 5 h to 10 h, preferably 6 h to 8 h, to ensure that the reaction is fully carried out. Specifically, the low-temperature pyrolysis time can be 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, etc.

[0050] In some embodiments, the low-temperature pyrolysis process is carried out in a pyrolysis furnace, and the temperature is raised to the pyrolysis temperature at a controlled heating rate of 5°C / min-10°C / min. Specifically, the heating rate can be 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, etc.

[0051] In some embodiments, the gas used to form the oxidizing atmosphere is selected from at least one of oxygen and ozone, and can be any one or more of the above, preferably ozone, which has a stronger oxidizing ability and is more conducive to promoting the full progress of the reaction.

[0052] In some embodiments, the introduction rate of the gas used to form the oxidizing atmosphere is 1 mL / min-3 mL / min, and the amount of the oxidizing atmosphere is controlled to ensure the reaction rate.

[0053] S4. Post-processing

[0054] After the low-temperature pyrolysis reaction is completed, the HF waste gas generated by the reaction can be treated, and the pyrolysis debris can be sorted to obtain copper and aluminum foil and battery powder for subsequent recycling.

[0055] There is no limitation on the method for treating HF waste gas. HF waste gas may be treated by passing it into lime water, but is not limited to this method.

[0056] In some embodiments, a double-layer screen can be used to screen the pyrolyzed crushed material, so that the upper layer is the pyrolyzed battery material (mainly copper and aluminum foil) and the bottom layer is the battery powder removed during the pyrolysis process.

[0057] The features and performance of the present disclosure are further described in detail below with reference to the embodiments.

[0058] Example 1

[0059] This embodiment provides a method for removing PVDF from waste lithium batteries applied to the entire lithium battery industry chain, comprising the following steps:

[0060] (1) Waste ternary lithium-ion batteries (60Ah square soft pack ternary (lithium nickel cobalt manganese oxide Li (Ni 0.8 Co 0.1 Mn 0.1 )O2, the same below) is discharged, disassembled and crushed to obtain crushed materials with a particle size of less than 5 cm.

[0061] (2) Add 100 g of 35% by mass silicate solution to 100 g of the above crushed material, and stir to evenly distribute the solution in the battery crushed material to obtain a mixture of the battery crushed material and the silicate solution.

[0062] (3) The mixture in (2) was placed in a pyrolysis furnace and heated to 320°C at a heating rate of 8°C / min for pyrolysis for 8 h. Ozone was introduced during the pyrolysis process at a rate of 2 mL / min.

[0063] (4) The generated HF waste gas is introduced into lime water for treatment. After the pyrolysis reaction is completed, the material in the pyrolysis furnace is sieved using a double-layer screen to obtain an upper layer of battery material after pyrolysis and a bottom layer of battery powder removed during the pyrolysis process.

[0064] Monitoring the situation inside the pyrolysis furnace: It was observed that there seemed to be droplets dissolving out of the surface of the crushed material, and the volume expanded slightly, but no other obvious changes were observed. When the temperature was increased until the temperature inside the furnace remained constant, the powder fell off obviously and a metallic luster appeared.

[0065] Example 2

[0066] The difference between this embodiment and embodiment 1 is that step (3) is as follows:

[0067] The mixture of battery scraps and silicic acid solution was placed in a pyrolysis furnace and heated to 350°C at a heating rate of 10°C / min for pyrolysis for 6 hours. Ozone was introduced during the pyrolysis process at a rate of 2 mL / min.

[0068] Monitoring the situation inside the pyrolysis furnace: It was observed that there seemed to be droplets dissolving out of the surface of the crushed material, and the volume expanded slightly, but no other obvious changes were observed. When the temperature was increased until the temperature inside the furnace remained constant, the powder fell off obviously and a metallic luster appeared.

[0069] Comparative Example 1

[0070] The only difference from Example 1 is that in this example, silicic acid is not decomposed in situ. The specific steps are as follows:

[0071] (1) The waste ternary lithium-ion batteries are discharged, disassembled and crushed to obtain crushed materials with a particle size of less than 5 cm.

[0072] (2) Take Xg of silicic acid solution with a mass fraction of X%, heat it to 160°C, wait for it to decompose to produce silicon dioxide and water vapor, then add the battery fragments in step (1) to the decomposed solution, and stir to make the solution evenly distributed in the battery fragments to form a mixture.

[0073] (3) The mixture in step (2) was heated to 320° C. in a pyrolysis furnace at a heating rate of 8° C. / min and pyrolyzed for 8 h. Ozone was introduced during the pyrolysis process at a rate of 2 mL / min.

[0074] (4) The generated HF waste gas is introduced into lime water for treatment. After the pyrolysis reaction is completed, the material in the pyrolysis furnace is sieved using a double-layer screen to obtain an upper layer of battery material after pyrolysis and a bottom layer of battery powder removed during the pyrolysis process.

[0075] Monitoring the situation in the pyrolysis furnace: When silanol is not generated in situ, it is observed that there are droplets dissolving out of the surface of the crushed material, and the volume expands slightly. No other obvious changes are observed. When the temperature is increased until the temperature in the furnace remains constant, the powder falls off and a small amount of metallic luster appears.

[0076] Comparative Example 2

[0077] The only difference from Example 1 is that the reaction temperature in step (3) is 300°C.

[0078] Monitoring the situation inside the pyrolysis furnace: When the temperature is lower than the catalytic temperature, a small amount of molten liquid droplets appear on the surface of the crushed material. The temperature inside the furnace remains constant, and there is no obvious powder shedding and no obvious metallic luster.

[0079] Comparative Example 3

[0080] The only difference from Example 1 is that no catalysis is performed. The specific steps are as follows:

[0081] (1) The waste ternary lithium-ion batteries are discharged, disassembled and crushed to obtain crushed materials with a particle size of less than 5 cm.

[0082] (2) Add the crushed material into the pyrolysis furnace and control the filling rate of the pyrolysis furnace to 100%.

[0083] (3) heating the pyrolysis furnace to 350°C at a heating rate of 8°C / min and performing pyrolysis for 8 h;

[0084] (4) The generated HF waste gas is introduced into lime water for treatment. After the pyrolysis reaction is completed, the material in the pyrolysis furnace is sieved using a double-layer screen to obtain an upper layer of battery material after pyrolysis and a bottom layer of battery powder removed during the pyrolysis process.

[0085] Monitoring the situation inside the pyrolysis furnace: When no catalytic pyrolysis is carried out, a small amount of molten liquid droplets appear on the surface of the crushed material, which agglomerate after cooling. The temperature inside the furnace remains constant, and a small amount of powder falls off obviously, with some metallic luster.

[0086] Comparative Example 4

[0087] The difference from Example 1 is that ordinary silicon dioxide is directly added. The specific steps are as follows:

[0088] (1) The waste ternary lithium-ion batteries are discharged, disassembled and crushed to obtain crushed materials with a particle size of less than 5 cm.

[0089] (2) Add 35 g of silicon dioxide to 100 g of the above crushed material, and stir to evenly distribute the battery crushed material and silicon dioxide to obtain a mixture of the two.

[0090] (3) The mixture in (2) was placed in a pyrolysis furnace and heated to 350°C at a heating rate of 8°C / min for pyrolysis for 8 h. Ozone was introduced during the pyrolysis process at a rate of 2 mL / min.

[0091] (4) The generated HF waste gas is introduced into lime water for treatment. After the pyrolysis reaction is completed, the material in the pyrolysis furnace is sieved using a double-layer screen to obtain an upper layer of battery material after pyrolysis and a bottom layer of battery powder removed during the pyrolysis process.

[0092] Monitoring the situation inside the pyrolysis furnace: trace molten liquid droplets appear on the surface of the crushed material, the temperature inside the furnace remains constant, the powder falls off, and a small amount of metallic luster appears.

[0093] Comparative Example 5

[0094] The only difference from Example 1 is that ozone is not introduced during the pyrolysis process in step (3).

[0095] Monitoring the situation inside the pyrolysis furnace: It was observed that there seemed to be droplets dissolving out of the surface of the crushed material, and the volume expanded slightly, but no other obvious changes were observed. When the temperature was increased until the temperature inside the furnace remained constant, the powder fell off and a metallic luster appeared.

[0096] Comparative Example 6

[0097] The difference from Example 1 is that the amount of silicic acid solution added is insufficient to evenly distribute the solution in the battery crushed material, and in step 2, 50 g of silicic acid solution with a mass fraction of 35% is added.

[0098] Monitoring the situation inside the pyrolysis furnace: trace molten liquid droplets appear on the surface of the crushed material, the temperature inside the furnace remains constant, the powder falls off, and a small amount of metallic luster appears.

[0099] Comparative Example 7

[0100] The only difference from the embodiment is that conventional high-temperature pyrolysis is used, and the specific steps are as follows:

[0101] (1) The waste ternary lithium-ion batteries are discharged, disassembled and crushed to obtain crushed materials with a particle size of less than 5 cm.

[0102] (2) Add the crushed material into the pyrolysis furnace and control the filling rate of the pyrolysis furnace to 100%.

[0103] (3) heating the pyrolysis furnace to 600°C at a heating rate of 8°C / min for pyrolysis for 8 h;

[0104] (4) The generated HF waste gas is introduced into lime water for treatment. After the pyrolysis reaction is completed, the material in the pyrolysis furnace is sieved using a double-layer screen to obtain an upper layer of battery material after pyrolysis and a bottom layer of battery powder removed during the pyrolysis process.

[0105] Monitoring the conditions inside the pyrolysis furnace: When conventional high-temperature pyrolysis is used, after the temperature inside the furnace reaches 600°C, flames appear, the temperature becomes uncontrolled and rises on its own, sparks fly rapidly, and the material becomes red and molten. After cooling, no obvious metallic luster appears.

[0106] Test Example 1

[0107] The aluminum content and copper content in the battery powder, and the nickel content, cobalt content, and manganese content in the metal foil were obtained in the test examples and comparative examples. The test results are shown in Table 1:

[0108] Table 1 Element contents of battery powder and metal foil obtained in Examples and Comparative Examples

[0109]

[0110] The results show that Examples 1-2 and Comparative Example 1 illustrate that when silanol groups are generated in situ, the catalytic effect produced is more obvious.

[0111] It should be added that the catalytic effect of the silicate solution is to promote the pyrolysis failure of PVDF, so that the positive and negative battery powders are separated from the copper and aluminum foils. The effect of PVDF pyrolysis failure can be distinguished from the copper and aluminum foil content in the battery powder and the nickel, cobalt and manganese content in the copper and aluminum foils. If the content of these values ​​is low, it proves that the viscosity of PVDF has failed more.

[0112] In Comparative Examples 2-3, a large amount of transition metal remains on the metal foil, indicating that when the catalytic temperature is insufficient or there is no catalysis, the PVDF pyrolysis temperature is insufficient and it is difficult to completely carbonize and fail.

[0113] In Comparative Example 4, when only silicon dioxide was added, the silicon dioxide contained fewer silanol groups and the catalytic effect was poor.

[0114] In Comparative Example 5, without the introduction of ozone for further oxidation, the thermal decomposition effect of PVDF was worse than that of Example 1.

[0115] In Comparative Example 6, the added silicic acid solution was insufficient to evenly distribute the solution in the battery crushed material, resulting in an insufficient catalytic reaction and a poorer pyrolysis effect than that of the examples.

[0116] In Comparative Example 7, due to the high temperature, a thermite reaction obviously occurred, and almost all of the aluminum was oxidized into the black powder, and no formed aluminum foil was obtained.

[0117] The preferred embodiments of the present disclosure are described in detail above, but the present disclosure is not limited thereto. Within the technical concept of the present disclosure, various simple variations of the technical solution of the present disclosure may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed by the present disclosure and fall within the scope of protection of the present disclosure.

[0118] Industrial Applicability

[0119] Lithium battery waste is mixed with a silicic acid solution and then subjected to low-temperature pyrolysis in an oxidizing atmosphere. During the reaction, the silicic acid decomposes in situ within the lithium battery waste to produce large amounts of silica and water. The silica surface is rich in silanol groups, which catalyze the pyrolysis of PVDF at relatively low temperatures. The presence of ozone further promotes PVDF pyrolysis. The overall process is easy to operate, requiring only standard mixing equipment and a pyrolysis furnace, making it suitable for industrial application.

Claims

1. A method for removing PVDF from waste lithium batteries applied to the entire lithium battery industry chain, characterized in that: include: A mixture of lithium battery waste and silicic acid is subjected to low-temperature pyrolysis at 320° C.-350° C., and the low-temperature pyrolysis process is carried out in an oxidizing atmosphere.

2. The method according to claim 1, characterized in that The temperature of the low-temperature pyrolysis is 330°C-340°C.

3. The method according to claim 1 or 2, characterized in that The low-temperature pyrolysis time is 5h-10h.

4. The method according to claim 3, characterized in that The low-temperature pyrolysis time is 6h-8h.

5. The method according to claim 1, wherein The low-temperature pyrolysis process is carried out in a pyrolysis furnace, and the temperature is raised to the pyrolysis temperature at a heating rate of 5°C / min-10°C / min.

6. The method according to claim 1, characterized in that The preparation process of the mixture comprises: mixing lithium battery waste and silicic acid solution.

7. The method according to claim 6, characterized in that The mass fraction of the silicic acid solution is 30-40%.

8. The method according to claim 6, characterized in that The mass ratio of the lithium battery waste to the silicic acid solution is 1:1-1.

2.

9. The method according to claim 8, characterized in that The mass ratio of the lithium battery waste to the silicic acid solution is 1:1.05-1.

15.

10. The method according to claim 1, characterized in that The gas used to form the oxidizing atmosphere is selected from at least one of oxygen and ozone.

11. The method according to claim 10, characterized in that The gas used to form the oxidizing atmosphere is ozone.

12. The method according to claim 1, characterized in that The introduction rate of the gas used to form the oxidizing atmosphere is 1 mL / min-3 mL / min.

13. The method according to claim 1, wherein The preparation process of the lithium battery waste includes: pre-treating the waste lithium batteries to obtain crushed materials with particle size meeting the requirements.

14. The method according to claim 13, characterized in that The pretreatment includes discharging, disassembling and crushing in sequence.

15. The method according to claim 13, characterized in that The particle size of the lithium battery waste is less than 5 cm.

16. The method according to claim 15, characterized in that The particle size of the lithium battery waste is 1 cm to 3 cm.

17. The method according to claim 13, wherein The waste lithium battery is selected from at least one of nickel-cobalt-manganese ternary lithium-ion batteries, lithium iron phosphate batteries, lithium cobalt oxide batteries and lithium iron manganese phosphate batteries.

18. The method according to claim 1, wherein Also includes: The HF waste gas generated by the reaction is treated.

19. The method according to claim 18, characterized in that The HF waste gas is passed into lime water for treatment.

20. The method according to claim 1, wherein Also includes: The pyrolyzed scraps are sorted to obtain copper and aluminum foil and battery powder.

21. The method according to claim 20, characterized in that A double-layer screen is used to screen the pyrolyzed crushed materials.

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