A method for recycling waste lithium batteries by dual-electrode gradient oxidation

Abstract

The present invention relates to the field of lithium battery recycling technology and discloses a method for recycling waste lithium batteries by dual-electrode gradient oxidation, comprising the following steps: Step 1: placing a cathode and an anode at each end of an electrolytic cell, with a diaphragm separating the cathode and anode; Step 2: adding a mixed ionic liquid solution to the electrolytic cell; Step 3: adding a catalyst to the prepared electrolytic cell; Step 4: placing waste lithium battery positive electrode material in the solution; Step 5: adding a precipitant to the solution and, utilizing differences in solubility, filtering to obtain the desired lithium salt. In the present invention, in Step 3, the catalyst is directly added to the mixed ionic liquid solution in the electrolytic cell, allowing the waste battery material to directly contact the solution and undergo conversion during the reaction, eliminating pretreatment steps such as coating. This achieves the beneficial effect of designing a solid-liquid contact method for recycling battery materials, eliminating the troublesome coating process.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery recycling, and in particular to a method for recycling waste lithium batteries by dual-electrode gradient oxidation. Background Art

[0002] At present, the methods for recycling used lithium batteries on the market in my country include wet recycling and pyrolysis. Among them, pyrolysis requires high-temperature reactions (>1400°C), which consumes a lot of energy and causes element loss. Wet recycling uses acid and alkali reagents to dissolve battery materials and adopts corresponding precipitants to separate precious metal elements step by step, but the use of a large number of chemical reagents and cumbersome processes limit large-scale application. In recent years, the electrochemical recovery method has attracted widespread attention due to its low reagent consumption and high product purity. Its core reaction is to apply the crushed waste active material to the anode of the electrolytic cell, and use the anodic oxidation reaction to leach lithium ions into the solution. The remaining reactant waste residue is obtained by separation, and finally the lithium ions in the solution are precipitated by the difference in solubility. During the entire chemical reaction process, most of the recovered chemical substances are concentrated near the positive electrode, so it is called a single-electrode recovery reaction.

[0003] Generally speaking, there are the following technical problems in recycling waste lithium batteries using the above method:

[0004] There is significant room for improvement in recycling efficiency. According to the "Industry Standards for Comprehensive Utilization of Waste Power Batteries for New Energy Vehicles (2019 Edition)" issued by the Ministry of Industry and Information Technology of the People's Republic of China, the comprehensive recovery rate of nickel, cobalt, and manganese should be no less than 98%, and the recovery rate of lithium should be no less than 85%. There is still significant room for improvement in single-electrode recycling reactions.

[0005] The single-electrode recovery reaction is concentrated in the anode area, and the reaction in the cathode area is not effectively utilized, resulting in power loss.

[0006] The recovered reactants need to be coated on the electrodes, which involves many steps and the recovery efficiency is greatly affected by the coating quality.

[0007] The oxidizing property of the reagent cannot be utilized in a gradient, which means that the reaction in the anode area requires a certain threshold voltage, which cannot be adjusted at will, and thus the efficiency of the recovery reaction is not high. Summary of the Invention

[0008] Technical issues solved:

[0009] In response to the shortcomings of the existing technology, the present invention provides a method for recycling waste lithium batteries through dual-electrode gradient oxidation. It has the advantages of designing solid-liquid contact to recycle battery materials, eliminating the trouble of the coating process; designing anode and cathode bipolar technology to improve charge utilization, and using ionic liquids to enhance ion activity; through the design of anode and cathode segmented combination, the electrical energy can be further controlled and utilized, and the oxidizing property of the prepared gradient redox pair is further improved with the help of catalysts, thereby solving the problems of the above-mentioned technologies.

[0010] Technical solution:

[0011] To achieve the above object, the present invention provides the following technical solution: a method for recycling waste lithium batteries by dual-electrode gradient oxidation, comprising the following steps:

[0012] Step 1: Place the cathode and anode at both ends of the electrolytic cell, and separate the positive and negative electrodes with a diaphragm in the middle;

[0013] Step 2: Add the mixed ionic liquid solution to the electrolytic cell in an amount of 10% to 80% of the volume of the electrolytic cell, blow gas into the cathode at a gas blowing rate of 0.1 L / min to 5000 L / min, apply a voltage of 1.0 to 200 volts between the cathode and the anode, and use an electrochemical anode-cathode bipolar method to simultaneously prepare an oxidizing redox pair in the electrolytic cell to form a composite oxidation system;

[0014] Step 3: Add catalyst to the prepared electrolytic cell. The amount of catalyst is (0.1-20)*10 of the power consumption. -8 Coulomb, catalytic time is 0.1-10 hours;

[0015] Step 4: Place the waste lithium battery positive electrode material into the above solution. The strong oxidizing property of the composite redox couple in the solution oxidizes the positive electrode material, and the lithium ions in the positive electrode material are released from the bulk phase of the material and enter the ionic liquid. The corresponding positive electrode material will become a positive electrode material residue. At the same time, the redox couple is reduced to the original solute and continues to participate in the redox reaction. The waste positive electrode material residue is obtained by filtration, and the lithium ions are enriched in the ionic liquid.

[0016] Step 5: Add the precipitant to the solution and filter to obtain the desired lithium salt by utilizing the difference in solubility;

[0017] In step 2, the anode and cathode adopt a segmented combination design, and the precise control of the amount of electricity and the gradient preparation of the redox couple are achieved by adjusting the resistance and surface state of each segment. The electrode arrangement in the electrolytic cell adopts a series segmented electrode, a parallel segmented electrode or a series-parallel combination segmented electrode method.

[0018] Preferably, the series segmented electrodes in step 2 are multiple electrodes connected in series, and by adjusting the type of electrodes, the type of solution between the electrodes, and controlling the voltage between the electrodes, ions of different oxidizing properties in the solution are guided to react simultaneously on the electrodes, thereby achieving gradient oxidation of the solute.

[0019] Preferably, in step 2, the parallel segmented electrodes are first connected in series at the cathode or anode segments, and then paired with the counter electrode to form a cathode-affected bipolar system, and the voltage of the cathode-affected bipolar system composed of each segmented electrode is the same.

[0020] Preferably, in step 2, the series-parallel combination of segmented electrodes simultaneously controls the voltage and charge distribution.

[0021] Preferably, the electric charge of 1 mol of electrons in step 3 is 96500 coulombs, which is converted from coulombs to electric charge of 1 / 1000000, and the amount of catalyst added is 0.1-20% of the electric charge, and the dosage is (0.1-20)*10 -8 .

[0022] Preferably, the ionic liquid solvent in step 2 is acetic acid-3-methylimidazolium hexafluorophosphate; 1-propyl-3-methylimidazolium hexafluorophosphate; boron pentafluoride anthraquinone ionic liquid; ethylammonium nitrate; 1-ethyl-3-methylimidazolium tetrafluoroborate; 1-ethyl-1-methylpiperidinium peracid salt; 1-propyl-1-methylpiperidinium bromide; 1-propyl-1-methylpiperidinium tetrafluoroborate; 1-propyl-1-methylpiperidinium hexafluorophosphate; 1-propyl-1-methylpiperidinium dihydrogen phosphate; 1-ethyl-1-methylpyrrolidinium bromide The invention is prepared by mixing one or more of the following: salt; 1-ethyl-1-methylpyrrolidine methanesulfonate; 1-ethyl-1-methylpyrrolidine p-toluenesulfonate; 1-ethyl-1-methylpyrrolidine bis(trifluoromethanesulfonyl)imide; 1-propyl-1-methylpyrrolidine hexafluorophosphate; 1-propyl-1-methylpyrrolidine methanesulfonate; N-butyl, methylpyrrolidine peramine salt; N-ethyl, methylmorpholine bromide; N-ethyl, methylmorpholine iodide; N-ethyl, methylmorpholine tetrafluoroborate; and N-ethyl, methylmorpholine hexafluorophosphate.

[0023] Preferably, the solute in step 2 is one or more of potassium sulfate, sodium sulfate, ammonium sulfate, sulfuric acid, sodium chloride, potassium chloride, ammonium chloride, hydrochloric acid, sodium carbonate, potassium carbonate, ammonium carbonate, potassium perchlorate, sodium perchlorate, ammonium perchlorate, perchloric acid, sulfur trioxide, sulfur dioxide, ammonium persulfate, sodium persulfate, potassium persulfate, ammonium bisulfate, sodium bisulfate, and potassium bisulfate.

[0024] Preferably, the gas in step 2 is one or more of oxygen, nitrogen, carbon dioxide, and argon; the anode material in step 2 is a complex of one or more of the elements Pt, Ti, TiO2, RuO2, IrO2, SnO2, PbO2, graphite, diamond, Pd, Au, B, Ni, Mn, Co, and C3N4; and the cathode material is a complex of one or more of the elements Pt, Ti, Ru, Ir, Sn, Pb, C, B, Ni, Mn, and Co.

[0025] Preferably, the catalyst in step 3 is graphene, Fe, Fe 2+ 、Fe 3+ , iron oxide, iron sulfide, MgO, MoO3, carbon material, TiO2 one or more; the positive electrode material of the waste lithium battery in the step four is one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganate, lithium manganese iron phosphate, lithium cobaltate, lithium vanadium phosphate, lithium vanadium fluorophosphate, and ternary material products.

[0026] Preferably, the precipitant in step 5 is one or more of sodium fluoride, potassium fluoride, ammonium phosphate, ammonium hydrogen phosphate and ammonium dihydrogen phosphate, sodium carbonate, potassium carbonate, ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, potassium bicarbonate, sodium phosphate, and potassium phosphate.

[0027] Compared with the prior art, the present invention provides a method for recycling waste lithium batteries by dual-electrode gradient oxidation, which has the following beneficial effects:

[0028] 1. The present invention creates an effective electrochemical reaction environment by arranging a cathode and an anode in an electrolytic cell and using a diaphragm to separate the cathode and the anode, so that the electrode material is in full contact with the electrolyte, without the need for an additional coating process to ensure the contact effect. Gradient oxidation and reduction reactions are carried out in the electrolytic cell, and a redox pair with strong oxidizing properties can be generated in the electrolytic cell. The reaction directly acts on the positive electrode material of the waste lithium battery, and no additional coating treatment is required for the material. In step three, the catalyst is directly added to the mixed ionic liquid solution in the electrolytic cell, so that the waste battery material is in direct contact with the solution and converted in the reaction, eliminating pretreatment steps such as coating, achieving the beneficial effect of designing solid-liquid contact to recover battery materials and eliminating the trouble of the coating process.

[0029] 2. The present invention uses a cathode and an anode in the electrolytic cell and uses a segmented electrode design to precisely control the current and voltage, which can effectively adjust the resistance and surface state of each electrode segment, thereby optimizing the charge distribution and utilization efficiency, ensuring full utilization of the charge on the electrode and efficient reaction. In step 2, a mixed ionic liquid is used as the electrolyte. The ionic liquid has high electrical conductivity and stability, and can effectively enhance the activity of ions in the solution, making the electrolysis reaction process more efficient, thereby increasing the redox reaction rate of the battery material. By generating a composite redox pair in the electrolytic cell and using these redox pairs to carry out electrochemical reactions, the charge utilization rate is improved. The formation of the composite system enables the reaction to proceed within a wider voltage and current range, thereby improving the efficiency of the entire system, and achieving the beneficial effects of designing anode and cathode bipolar technology to improve charge utilization and using ionic liquids to enhance ion activity.

[0030] 3. The present invention guides the ions in the solution to undergo gradient oxidation on different electrodes by adjusting the type of electrodes and the voltage between the electrodes, allowing redox pairs of different strengths to be generated on different electrodes, thereby realizing graded control of the use of electric energy and improving the efficiency of electric energy utilization. The composite salt solution used is compatible with the surface state of the electrode, and can achieve gradient control of the redox pair at low, medium and high oxidizing properties, achieving the beneficial effect of further controllable utilization of electric energy through the segmented combination design of the anode and cathode, and further improving the oxidizing property of the prepared gradient redox pair with the help of a catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the series segmented electrodes of the present invention;

[0032] Figure 2 This is a schematic diagram of the parallel segmented electrodes of the present invention;

[0033] Figure 3 Schematic diagram of the hybrid segmented electrode of the present invention. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] See also Figure 1-3 A method for recycling waste lithium batteries by dual-electrode gradient oxidation comprises the following steps:

[0036] Step 1: Place the cathode and anode at both ends of the electrolytic cell, and separate the positive and negative electrodes with a diaphragm in the middle;

[0037] Step 2: Add the mixed ionic liquid solution to the electrolytic cell in an amount of 10% to 80% of the volume of the electrolytic cell, blow gas into the cathode at a gas blowing rate of 0.1 L / min to 5000 L / min, apply a voltage of 1.0 to 200 volts between the cathode and the anode, and use an electrochemical anode-cathode bipolar method to simultaneously prepare an oxidizing redox pair in the electrolytic cell to form a composite oxidation system;

[0038] Step 3: Add catalyst to the prepared electrolytic cell. The amount of catalyst is (0.1-20)*10 of the power consumption. -8 Coulomb, catalytic time is 0.1-10 hours;

[0039] Step 4: Place the waste lithium battery positive electrode material into the above solution. The strong oxidizing property of the composite redox couple in the solution oxidizes the positive electrode material, and the lithium ions in the positive electrode material are released from the bulk phase of the material and enter the ionic liquid. The corresponding positive electrode material will become a positive electrode material residue. At the same time, the redox couple is reduced to the original solute and continues to participate in the redox reaction. The waste positive electrode material residue is obtained by filtration, and the lithium ions are enriched in the ionic liquid.

[0040] Step 5: Add the precipitant to the solution and filter to obtain the desired lithium salt by utilizing the difference in solubility;

[0041] In step 2, the anode and cathode adopt a segmented combination design. By adjusting the resistance and surface state of each segment, precise control of the amount of electricity and gradient preparation of the redox couple are achieved. The electrode arrangement in the electrolytic cell adopts a series segmented electrode, a parallel segmented electrode or a series-parallel combination segmented electrode method.

[0042] Specifically, in step 2, the series segmented electrodes are multiple electrodes connected in series. By adjusting the type of electrodes, the type of solution between the electrodes, and the voltage between the electrodes, ions of different oxidizing properties in the solution are guided to react simultaneously on the electrodes, thereby achieving gradient oxidation of the solute.

[0043] The use of ionic liquid as electrolyte enhances the activity of ions therein and improves the conversion efficiency of electrical energy to chemical energy (redox pair).

[0044] The use of anode-cathode bipolar technology to prepare redox pairs not only produces redox pairs at the anode, but also produces the same effect at the cathode, thereby improving the utilization rate of electrical energy.

[0045] A segmented combination design of anode and cathode is designed to achieve precise control of the reaction at the electrode-solution interface by adjusting the resistance and surface state of each segment, while more reasonably distributing the surface charge density.

[0046] The composite salt solution used is compatible with the surface state of the electrode, enabling gradient control of the redox pair at low, medium and high oxidizing properties.

[0047] The catalyst added to the electrolytic cell utilizes its highly efficient catalytic reaction to further catalyze the composite redox pair into oxidizing substances with stronger oxidizing properties and larger quantities.

[0048] Bipolar electrode structure: A cathode and anode are used in the electrolytic cell, and the current and voltage are precisely controlled through a segmented electrode design (including series, parallel, and series-parallel combination segmented electrodes). This design can effectively adjust the resistance and surface state of each electrode segment, thereby optimizing charge distribution and utilization efficiency, ensuring full utilization of the charge on the electrode and efficient reaction.

[0049] Improved charge utilization: This precisely controlled electrode layout achieves a gradient charge distribution and gradient redox pair preparation, thereby improving charge utilization. This means that the charges in the electrolyzer can participate in the reaction more evenly, improving overall reaction efficiency and battery material recovery.

[0050] Advantages of ionic liquids: In step 2, a mixed ionic liquid is used as the electrolyte. Ionic liquids have high conductivity and stability, effectively enhancing the activity of ions in the solution. This high ionic activity makes the electrolysis process more efficient, thereby increasing the redox reaction rate of the battery material.

[0051] Enhanced ion activity: The high ion activity of ionic liquids helps improve ion migration and reaction efficiency during electrolysis. By optimizing the choice of ionic liquid (such as 3-methylimidazolium hexafluorophosphate), charge utilization and reaction efficiency can be further improved.

[0052] Gas bubbling: In step 2, the gas bubbling technology at the cathode (such as oxygen, nitrogen, etc.) further improves the mixing efficiency of the electrolyte and the reaction rate of the electrode. The gas bubbling helps to fully contact the gas-liquid phase and transfer ions, thereby enhancing the utilization of charge and the uniformity of the reaction.

[0053] Specifically, in step 2, the parallel segmented electrodes are first connected in series at the cathode or anode segments, and then paired with the counter electrode to form a cathode-affected bipolar system, and the voltage of the cathode-affected bipolar system composed of each segmented electrode is the same.

[0054] Specifically, in step 2, the series-parallel combination of segmented electrodes simultaneously controls the voltage and charge distribution.

[0055] Specifically, in step 3, the charge of 1 mol of electrons is 96500 coulombs, which is converted from coulombs to charge of 1 / 1000000. The amount of catalyst added is 0.1-20% of the charge, and the amount used is (0.1-20)*10 -8 .

[0056] Specifically, the ionic liquid solvent in step 2 is acetic acid-3-methylimidazolium hexafluorophosphate; 1-propyl-3-methylimidazolium hexafluorophosphate; boron pentafluoride anthraquinone ionic liquid; ethylammonium nitrate; 1-ethyl-3-methylimidazolium tetrafluoroborate; 1-ethyl-1-methylpiperidinium peracid salt; 1-propyl-1-methylpiperidinium bromide; 1-propyl-1-methylpiperidinium tetrafluoroborate; 1-propyl-1-methylpiperidinium hexafluorophosphate; 1-propyl-1-methylpiperidinium dihydrogen phosphate; 1-ethyl-1-methylpyrrolidinium bromide ; 1-ethyl-1-methylpyrrolidine methanesulfonate; 1-ethyl-1-methylpyrrolidine p-toluenesulfonate; 1-ethyl-1-methylpyrrolidine bis(trifluoromethanesulfonyl)imide; 1-propyl-1-methylpyrrolidine hexafluorophosphate; 1-propyl-1-methylpyrrolidine methanesulfonate; N-butyl, methylpyrrolidine peramine; N-ethyl, methylmorpholine bromide; N-ethyl, methylmorpholine iodide; N-ethyl, methylmorpholine tetrafluoroborate; N-ethyl, methylmorpholine hexafluorophosphate.

[0057] Specifically, the solute in step 2 is one or more of potassium sulfate, sodium sulfate, ammonium sulfate, sulfuric acid, sodium chloride, potassium chloride, ammonium chloride, hydrochloric acid, sodium carbonate, potassium carbonate, ammonium carbonate, potassium perchlorate, sodium perchlorate, ammonium perchlorate, perchloric acid, sulfur trioxide, sulfur dioxide, ammonium persulfate, sodium persulfate, potassium persulfate, ammonium bisulfate, sodium bisulfate, and potassium bisulfate.

[0058] Specifically, the gas in step 2 is one or more of oxygen, nitrogen, carbon dioxide, and argon; the anode material in step 2 is a complex of one or more of the elements Pt, Ti, TiO2, RuO2, IrO2, SnO2, PbO2, graphite, diamond, Pd, Au, B, Ni, Mn, Co, and C3N4; and the cathode material is a complex of one or more of the elements Pt, Ti, Ru, Ir, Sn, Pb, C, B, Ni, Mn, and Co.

[0059] Specifically, the catalyst in step 3 is graphene, Fe, Fe 2+ 、Fe 3+ , iron oxide, iron sulfide, MgO, MoO3, carbon material, TiO2 one or more; the positive electrode material of the waste lithium battery in the step four is one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganate, lithium manganese iron phosphate, lithium cobaltate, lithium vanadium phosphate, lithium vanadium fluorophosphate, and ternary material products.

[0060] Specifically, the precipitant in step five is one or more of sodium fluoride, potassium fluoride, ammonium phosphate, ammonium hydrogen phosphate and ammonium dihydrogen phosphate, sodium carbonate, potassium carbonate, ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, potassium bicarbonate, sodium phosphate, and potassium phosphate.

[0061] Example 1

[0062] like Figure 1 As shown, the series segmented electrode design utilizes multiple electrodes in series. By adjusting the type of electrodes, the type of solution between the electrodes, and the voltage between the electrodes, it guides ions of different oxidizing properties in the solution to react simultaneously on the electrodes, achieving gradient oxidation of the solute. The redox pair generation rate is increased by 120%, and the electrical energy-chemical energy conversion efficiency is increased to 91%.

[0063] Example 2

[0064] like Figure 2 As shown, the parallel segmented electrodes are first connected in series at the cathode or anode, and then paired with a counter electrode to form a cation-cation bipolar system. Each segmented electrode in the cation-cation bipolar system has the same voltage but different charges. Therefore, by controlling the charge, the absorption and catalytic properties of the electrode surface can be specifically adjusted. Experiments have shown that the parallel segmented electrodes increase the redox couple formation rate by 140% and the electrical-to-chemical energy conversion efficiency to 93.2%.

[0065] Example 3

[0066] like Figure 3 As shown, the series-parallel combination of segmented electrodes simultaneously controls the voltage and charge distribution, more accurately controls the reaction on the electrode surface, increases the redox pair generation rate by 162%, and increases the electrical energy-chemical energy conversion efficiency to 96.7%.

[0067] While embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for recycling waste lithium batteries by dual-electrode gradient oxidation, characterized in that: The following steps are involved: Step 1: Place the cathode and anode at both ends of the electrolytic cell, and separate the positive and negative electrodes with a diaphragm in the middle; Step 2: Add a mixed ionic liquid solution to the electrolytic cell in an amount of 10% to 80% of the volume of the electrolytic cell, blow gas into the cathode at a gas blowing rate of 0.1 L / min to 5000 L / min, apply a voltage of 1.0 to 200 volts between the cathode and the anode, and use an electrochemical anode-cathode bipolar method to simultaneously prepare an oxidizing redox pair in the electrolytic cell to form a composite oxidation system; Step 3: Adding catalyst to the prepared electrolytic cell for a catalytic time of 0.1-10 hours; Step 4: Place the waste lithium battery positive electrode material into the above solution. The strong oxidizing property of the composite redox couple in the solution oxidizes the positive electrode material, and the lithium ions in the positive electrode material are released from the bulk phase of the material and enter the ionic liquid. The corresponding positive electrode material will become a positive electrode material residue. At the same time, the redox couple is reduced to the original solute and continues to participate in the redox reaction. The waste positive electrode material residue is obtained by filtration, and the lithium ions are enriched in the ionic liquid. Step 5: Add the precipitant to the solution and filter to obtain the desired lithium salt by utilizing the difference in solubility; In step 2, the anode and cathode are designed in a segmented combination, and the precise control of the amount of electricity and the gradient preparation of the redox couple are achieved by adjusting the resistance and surface state of each segment. The electrodes in the electrolytic cell are arranged in a manner of serial segmented electrodes, parallel segmented electrodes, or a series-parallel combination of segmented electrodes. The unit of power consumption in step 3 is coulomb; The ionic liquid solvent in step 2 is prepared by mixing one or more of 1-propyl-3-methylimidazolium hexafluorophosphate; ethylammonium nitrate; 1-ethyl-3-methylimidazolium tetrafluoroborate; 1-ethyl-1-methylpyrrolidine methanesulfonate; 1-ethyl-1-methylpyrrolidine p-toluenesulfonate; 1-propyl-1-methylpyrrolidine hexafluorophosphate; N-ethyl, methylmorpholine tetrafluoroborate; and N-ethyl, methylmorpholine hexafluorophosphate. The solute in step 2 is one or more of potassium sulfate, sodium sulfate, ammonium sulfate, sodium chloride, potassium chloride, ammonium chloride, potassium perchlorate, sodium perchlorate, ammonium perchlorate, perchloric acid, ammonium persulfate, sodium persulfate, potassium persulfate, ammonium bisulfate, sodium bisulfate, and potassium bisulfate; The amount of the catalyst added in step 3 is (0.1-20)% of the electricity.

2. The method for recycling waste lithium batteries by dual-electrode gradient oxidation according to claim 1, characterized in that: In the second step, the series segmented electrodes are multiple electrodes connected in series. By adjusting the type of electrodes and the type of solution between the electrodes, the voltage between the electrodes is controlled, and the ions of different oxidizing properties in the solution are guided to react simultaneously on the electrodes, thereby achieving gradient oxidation of the solute.

3. The method for recycling waste lithium batteries by dual-electrode gradient oxidation according to claim 1, characterized in that: In step 2, the parallel segmented electrodes are first connected in series at the cathode or anode segments, and then paired with the counter electrode to form a cathode-affected bipolar system. The voltage of the cathode-affected bipolar system composed of each segmented electrode is the same.

4. The method for recycling waste lithium batteries by dual-electrode gradient oxidation according to claim 1, characterized in that: In step 2, the series-parallel combination of segmented electrodes simultaneously controls the voltage and power distribution.

5. The method for recycling waste lithium batteries by dual-electrode gradient oxidation according to claim 1, characterized in that: The gas in step 2 is oxygen, and the anode material in step 2 is a composite of one or more elements selected from the group consisting of Pt, Ti, TiO2, RuO2, IrO2, SnO2, PbO2, graphite, diamond, Pd, Au, B, Ni, Mn, Co, and C3N4; the cathode material is a composite of one or more elements selected from the group consisting of Pt, Ti, Ru, Ir, Sn, Pb, C, B, Ni, Mn, and Co.

6. The method for recycling waste lithium batteries by dual-electrode gradient oxidation according to claim 1, characterized in that: The catalyst in step three is one or more of graphene, Fe, iron oxide, iron sulfide, MgO, MoO3, carbon material, and TiO2; the positive electrode material of the waste lithium battery in step four is one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganate, lithium manganese iron phosphate, lithium cobaltate, lithium vanadium phosphate, lithium vanadium fluorophosphate, and ternary material products.

7. The method for recycling waste lithium batteries by dual-electrode gradient oxidation according to claim 1, characterized in that: The precipitant in step 5 is one or more of sodium fluoride, potassium fluoride, ammonium phosphate, ammonium hydrogen phosphate and ammonium dihydrogen phosphate, sodium carbonate, potassium carbonate, ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, potassium bicarbonate, sodium phosphate, and potassium phosphate.

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